1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements routines for folding instructions into simpler forms 10 // that do not require creating new instructions. This does constant folding 11 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either 12 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value 13 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been 14 // simplified: This is usually true and assuming it simplifies the logic (if 15 // they have not been simplified then results are correct but maybe suboptimal). 16 // 17 //===----------------------------------------------------------------------===// 18 19 #include "llvm/Analysis/InstructionSimplify.h" 20 21 #include "llvm/ADT/STLExtras.h" 22 #include "llvm/ADT/SetVector.h" 23 #include "llvm/ADT/Statistic.h" 24 #include "llvm/Analysis/AliasAnalysis.h" 25 #include "llvm/Analysis/AssumptionCache.h" 26 #include "llvm/Analysis/CaptureTracking.h" 27 #include "llvm/Analysis/CmpInstAnalysis.h" 28 #include "llvm/Analysis/ConstantFolding.h" 29 #include "llvm/Analysis/InstSimplifyFolder.h" 30 #include "llvm/Analysis/LoopAnalysisManager.h" 31 #include "llvm/Analysis/MemoryBuiltins.h" 32 #include "llvm/Analysis/OverflowInstAnalysis.h" 33 #include "llvm/Analysis/TargetLibraryInfo.h" 34 #include "llvm/Analysis/ValueTracking.h" 35 #include "llvm/Analysis/VectorUtils.h" 36 #include "llvm/IR/ConstantRange.h" 37 #include "llvm/IR/DataLayout.h" 38 #include "llvm/IR/Dominators.h" 39 #include "llvm/IR/InstrTypes.h" 40 #include "llvm/IR/Instructions.h" 41 #include "llvm/IR/Operator.h" 42 #include "llvm/IR/PatternMatch.h" 43 #include "llvm/IR/Statepoint.h" 44 #include "llvm/Support/KnownBits.h" 45 #include <algorithm> 46 #include <optional> 47 using namespace llvm; 48 using namespace llvm::PatternMatch; 49 50 #define DEBUG_TYPE "instsimplify" 51 52 enum { RecursionLimit = 3 }; 53 54 STATISTIC(NumExpand, "Number of expansions"); 55 STATISTIC(NumReassoc, "Number of reassociations"); 56 57 static Value *simplifyAndInst(Value *, Value *, const SimplifyQuery &, 58 unsigned); 59 static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned); 60 static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &, 61 const SimplifyQuery &, unsigned); 62 static Value *simplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &, 63 unsigned); 64 static Value *simplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &, 65 const SimplifyQuery &, unsigned); 66 static Value *simplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &, 67 unsigned); 68 static Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 69 const SimplifyQuery &Q, unsigned MaxRecurse); 70 static Value *simplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned); 71 static Value *simplifyXorInst(Value *, Value *, const SimplifyQuery &, 72 unsigned); 73 static Value *simplifyCastInst(unsigned, Value *, Type *, const SimplifyQuery &, 74 unsigned); 75 static Value *simplifyGEPInst(Type *, Value *, ArrayRef<Value *>, 76 GEPNoWrapFlags, const SimplifyQuery &, unsigned); 77 static Value *simplifySelectInst(Value *, Value *, Value *, 78 const SimplifyQuery &, unsigned); 79 static Value *simplifyInstructionWithOperands(Instruction *I, 80 ArrayRef<Value *> NewOps, 81 const SimplifyQuery &SQ, 82 unsigned MaxRecurse); 83 84 static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal, 85 Value *FalseVal) { 86 BinaryOperator::BinaryOps BinOpCode; 87 if (auto *BO = dyn_cast<BinaryOperator>(Cond)) 88 BinOpCode = BO->getOpcode(); 89 else 90 return nullptr; 91 92 CmpInst::Predicate ExpectedPred; 93 if (BinOpCode == BinaryOperator::Or) { 94 ExpectedPred = ICmpInst::ICMP_NE; 95 } else if (BinOpCode == BinaryOperator::And) { 96 ExpectedPred = ICmpInst::ICMP_EQ; 97 } else 98 return nullptr; 99 100 // %A = icmp eq %TV, %FV 101 // %B = icmp eq %X, %Y (and one of these is a select operand) 102 // %C = and %A, %B 103 // %D = select %C, %TV, %FV 104 // --> 105 // %FV 106 107 // %A = icmp ne %TV, %FV 108 // %B = icmp ne %X, %Y (and one of these is a select operand) 109 // %C = or %A, %B 110 // %D = select %C, %TV, %FV 111 // --> 112 // %TV 113 Value *X, *Y; 114 if (!match(Cond, 115 m_c_BinOp(m_c_SpecificICmp(ExpectedPred, m_Specific(TrueVal), 116 m_Specific(FalseVal)), 117 m_SpecificICmp(ExpectedPred, m_Value(X), m_Value(Y))))) 118 return nullptr; 119 120 if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal) 121 return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal; 122 123 return nullptr; 124 } 125 126 /// For a boolean type or a vector of boolean type, return false or a vector 127 /// with every element false. 128 static Constant *getFalse(Type *Ty) { return ConstantInt::getFalse(Ty); } 129 130 /// For a boolean type or a vector of boolean type, return true or a vector 131 /// with every element true. 132 static Constant *getTrue(Type *Ty) { return ConstantInt::getTrue(Ty); } 133 134 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? 135 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, 136 Value *RHS) { 137 CmpInst *Cmp = dyn_cast<CmpInst>(V); 138 if (!Cmp) 139 return false; 140 CmpInst::Predicate CPred = Cmp->getPredicate(); 141 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); 142 if (CPred == Pred && CLHS == LHS && CRHS == RHS) 143 return true; 144 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && 145 CRHS == LHS; 146 } 147 148 /// Simplify comparison with true or false branch of select: 149 /// %sel = select i1 %cond, i32 %tv, i32 %fv 150 /// %cmp = icmp sle i32 %sel, %rhs 151 /// Compose new comparison by substituting %sel with either %tv or %fv 152 /// and see if it simplifies. 153 static Value *simplifyCmpSelCase(CmpInst::Predicate Pred, Value *LHS, 154 Value *RHS, Value *Cond, 155 const SimplifyQuery &Q, unsigned MaxRecurse, 156 Constant *TrueOrFalse) { 157 Value *SimplifiedCmp = simplifyCmpInst(Pred, LHS, RHS, Q, MaxRecurse); 158 if (SimplifiedCmp == Cond) { 159 // %cmp simplified to the select condition (%cond). 160 return TrueOrFalse; 161 } else if (!SimplifiedCmp && isSameCompare(Cond, Pred, LHS, RHS)) { 162 // It didn't simplify. However, if composed comparison is equivalent 163 // to the select condition (%cond) then we can replace it. 164 return TrueOrFalse; 165 } 166 return SimplifiedCmp; 167 } 168 169 /// Simplify comparison with true branch of select 170 static Value *simplifyCmpSelTrueCase(CmpInst::Predicate Pred, Value *LHS, 171 Value *RHS, Value *Cond, 172 const SimplifyQuery &Q, 173 unsigned MaxRecurse) { 174 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 175 getTrue(Cond->getType())); 176 } 177 178 /// Simplify comparison with false branch of select 179 static Value *simplifyCmpSelFalseCase(CmpInst::Predicate Pred, Value *LHS, 180 Value *RHS, Value *Cond, 181 const SimplifyQuery &Q, 182 unsigned MaxRecurse) { 183 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 184 getFalse(Cond->getType())); 185 } 186 187 /// We know comparison with both branches of select can be simplified, but they 188 /// are not equal. This routine handles some logical simplifications. 189 static Value *handleOtherCmpSelSimplifications(Value *TCmp, Value *FCmp, 190 Value *Cond, 191 const SimplifyQuery &Q, 192 unsigned MaxRecurse) { 193 // If the false value simplified to false, then the result of the compare 194 // is equal to "Cond && TCmp". This also catches the case when the false 195 // value simplified to false and the true value to true, returning "Cond". 196 // Folding select to and/or isn't poison-safe in general; impliesPoison 197 // checks whether folding it does not convert a well-defined value into 198 // poison. 199 if (match(FCmp, m_Zero()) && impliesPoison(TCmp, Cond)) 200 if (Value *V = simplifyAndInst(Cond, TCmp, Q, MaxRecurse)) 201 return V; 202 // If the true value simplified to true, then the result of the compare 203 // is equal to "Cond || FCmp". 204 if (match(TCmp, m_One()) && impliesPoison(FCmp, Cond)) 205 if (Value *V = simplifyOrInst(Cond, FCmp, Q, MaxRecurse)) 206 return V; 207 // Finally, if the false value simplified to true and the true value to 208 // false, then the result of the compare is equal to "!Cond". 209 if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 210 if (Value *V = simplifyXorInst( 211 Cond, Constant::getAllOnesValue(Cond->getType()), Q, MaxRecurse)) 212 return V; 213 return nullptr; 214 } 215 216 /// Does the given value dominate the specified phi node? 217 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 218 Instruction *I = dyn_cast<Instruction>(V); 219 if (!I) 220 // Arguments and constants dominate all instructions. 221 return true; 222 223 // If we have a DominatorTree then do a precise test. 224 if (DT) 225 return DT->dominates(I, P); 226 227 // Otherwise, if the instruction is in the entry block and is not an invoke, 228 // then it obviously dominates all phi nodes. 229 if (I->getParent()->isEntryBlock() && !isa<InvokeInst>(I) && 230 !isa<CallBrInst>(I)) 231 return true; 232 233 return false; 234 } 235 236 /// Try to simplify a binary operator of form "V op OtherOp" where V is 237 /// "(B0 opex B1)" by distributing 'op' across 'opex' as 238 /// "(B0 op OtherOp) opex (B1 op OtherOp)". 239 static Value *expandBinOp(Instruction::BinaryOps Opcode, Value *V, 240 Value *OtherOp, Instruction::BinaryOps OpcodeToExpand, 241 const SimplifyQuery &Q, unsigned MaxRecurse) { 242 auto *B = dyn_cast<BinaryOperator>(V); 243 if (!B || B->getOpcode() != OpcodeToExpand) 244 return nullptr; 245 Value *B0 = B->getOperand(0), *B1 = B->getOperand(1); 246 Value *L = 247 simplifyBinOp(Opcode, B0, OtherOp, Q.getWithoutUndef(), MaxRecurse); 248 if (!L) 249 return nullptr; 250 Value *R = 251 simplifyBinOp(Opcode, B1, OtherOp, Q.getWithoutUndef(), MaxRecurse); 252 if (!R) 253 return nullptr; 254 255 // Does the expanded pair of binops simplify to the existing binop? 256 if ((L == B0 && R == B1) || 257 (Instruction::isCommutative(OpcodeToExpand) && L == B1 && R == B0)) { 258 ++NumExpand; 259 return B; 260 } 261 262 // Otherwise, return "L op' R" if it simplifies. 263 Value *S = simplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse); 264 if (!S) 265 return nullptr; 266 267 ++NumExpand; 268 return S; 269 } 270 271 /// Try to simplify binops of form "A op (B op' C)" or the commuted variant by 272 /// distributing op over op'. 273 static Value *expandCommutativeBinOp(Instruction::BinaryOps Opcode, Value *L, 274 Value *R, 275 Instruction::BinaryOps OpcodeToExpand, 276 const SimplifyQuery &Q, 277 unsigned MaxRecurse) { 278 // Recursion is always used, so bail out at once if we already hit the limit. 279 if (!MaxRecurse--) 280 return nullptr; 281 282 if (Value *V = expandBinOp(Opcode, L, R, OpcodeToExpand, Q, MaxRecurse)) 283 return V; 284 if (Value *V = expandBinOp(Opcode, R, L, OpcodeToExpand, Q, MaxRecurse)) 285 return V; 286 return nullptr; 287 } 288 289 /// Generic simplifications for associative binary operations. 290 /// Returns the simpler value, or null if none was found. 291 static Value *simplifyAssociativeBinOp(Instruction::BinaryOps Opcode, 292 Value *LHS, Value *RHS, 293 const SimplifyQuery &Q, 294 unsigned MaxRecurse) { 295 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 296 297 // Recursion is always used, so bail out at once if we already hit the limit. 298 if (!MaxRecurse--) 299 return nullptr; 300 301 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 302 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 303 304 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 305 if (Op0 && Op0->getOpcode() == Opcode) { 306 Value *A = Op0->getOperand(0); 307 Value *B = Op0->getOperand(1); 308 Value *C = RHS; 309 310 // Does "B op C" simplify? 311 if (Value *V = simplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 312 // It does! Return "A op V" if it simplifies or is already available. 313 // If V equals B then "A op V" is just the LHS. 314 if (V == B) 315 return LHS; 316 // Otherwise return "A op V" if it simplifies. 317 if (Value *W = simplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { 318 ++NumReassoc; 319 return W; 320 } 321 } 322 } 323 324 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 325 if (Op1 && Op1->getOpcode() == Opcode) { 326 Value *A = LHS; 327 Value *B = Op1->getOperand(0); 328 Value *C = Op1->getOperand(1); 329 330 // Does "A op B" simplify? 331 if (Value *V = simplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { 332 // It does! Return "V op C" if it simplifies or is already available. 333 // If V equals B then "V op C" is just the RHS. 334 if (V == B) 335 return RHS; 336 // Otherwise return "V op C" if it simplifies. 337 if (Value *W = simplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { 338 ++NumReassoc; 339 return W; 340 } 341 } 342 } 343 344 // The remaining transforms require commutativity as well as associativity. 345 if (!Instruction::isCommutative(Opcode)) 346 return nullptr; 347 348 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 349 if (Op0 && Op0->getOpcode() == Opcode) { 350 Value *A = Op0->getOperand(0); 351 Value *B = Op0->getOperand(1); 352 Value *C = RHS; 353 354 // Does "C op A" simplify? 355 if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 356 // It does! Return "V op B" if it simplifies or is already available. 357 // If V equals A then "V op B" is just the LHS. 358 if (V == A) 359 return LHS; 360 // Otherwise return "V op B" if it simplifies. 361 if (Value *W = simplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { 362 ++NumReassoc; 363 return W; 364 } 365 } 366 } 367 368 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 369 if (Op1 && Op1->getOpcode() == Opcode) { 370 Value *A = LHS; 371 Value *B = Op1->getOperand(0); 372 Value *C = Op1->getOperand(1); 373 374 // Does "C op A" simplify? 375 if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 376 // It does! Return "B op V" if it simplifies or is already available. 377 // If V equals C then "B op V" is just the RHS. 378 if (V == C) 379 return RHS; 380 // Otherwise return "B op V" if it simplifies. 381 if (Value *W = simplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { 382 ++NumReassoc; 383 return W; 384 } 385 } 386 } 387 388 return nullptr; 389 } 390 391 /// In the case of a binary operation with a select instruction as an operand, 392 /// try to simplify the binop by seeing whether evaluating it on both branches 393 /// of the select results in the same value. Returns the common value if so, 394 /// otherwise returns null. 395 static Value *threadBinOpOverSelect(Instruction::BinaryOps Opcode, Value *LHS, 396 Value *RHS, const SimplifyQuery &Q, 397 unsigned MaxRecurse) { 398 // Recursion is always used, so bail out at once if we already hit the limit. 399 if (!MaxRecurse--) 400 return nullptr; 401 402 SelectInst *SI; 403 if (isa<SelectInst>(LHS)) { 404 SI = cast<SelectInst>(LHS); 405 } else { 406 assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 407 SI = cast<SelectInst>(RHS); 408 } 409 410 // Evaluate the BinOp on the true and false branches of the select. 411 Value *TV; 412 Value *FV; 413 if (SI == LHS) { 414 TV = simplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); 415 FV = simplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); 416 } else { 417 TV = simplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); 418 FV = simplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); 419 } 420 421 // If they simplified to the same value, then return the common value. 422 // If they both failed to simplify then return null. 423 if (TV == FV) 424 return TV; 425 426 // If one branch simplified to undef, return the other one. 427 if (TV && Q.isUndefValue(TV)) 428 return FV; 429 if (FV && Q.isUndefValue(FV)) 430 return TV; 431 432 // If applying the operation did not change the true and false select values, 433 // then the result of the binop is the select itself. 434 if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 435 return SI; 436 437 // If one branch simplified and the other did not, and the simplified 438 // value is equal to the unsimplified one, return the simplified value. 439 // For example, select (cond, X, X & Z) & Z -> X & Z. 440 if ((FV && !TV) || (TV && !FV)) { 441 // Check that the simplified value has the form "X op Y" where "op" is the 442 // same as the original operation. 443 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 444 if (Simplified && Simplified->getOpcode() == unsigned(Opcode) && 445 !Simplified->hasPoisonGeneratingFlags()) { 446 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 447 // We already know that "op" is the same as for the simplified value. See 448 // if the operands match too. If so, return the simplified value. 449 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 450 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 451 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 452 if (Simplified->getOperand(0) == UnsimplifiedLHS && 453 Simplified->getOperand(1) == UnsimplifiedRHS) 454 return Simplified; 455 if (Simplified->isCommutative() && 456 Simplified->getOperand(1) == UnsimplifiedLHS && 457 Simplified->getOperand(0) == UnsimplifiedRHS) 458 return Simplified; 459 } 460 } 461 462 return nullptr; 463 } 464 465 /// In the case of a comparison with a select instruction, try to simplify the 466 /// comparison by seeing whether both branches of the select result in the same 467 /// value. Returns the common value if so, otherwise returns null. 468 /// For example, if we have: 469 /// %tmp = select i1 %cmp, i32 1, i32 2 470 /// %cmp1 = icmp sle i32 %tmp, 3 471 /// We can simplify %cmp1 to true, because both branches of select are 472 /// less than 3. We compose new comparison by substituting %tmp with both 473 /// branches of select and see if it can be simplified. 474 static Value *threadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 475 Value *RHS, const SimplifyQuery &Q, 476 unsigned MaxRecurse) { 477 // Recursion is always used, so bail out at once if we already hit the limit. 478 if (!MaxRecurse--) 479 return nullptr; 480 481 // Make sure the select is on the LHS. 482 if (!isa<SelectInst>(LHS)) { 483 std::swap(LHS, RHS); 484 Pred = CmpInst::getSwappedPredicate(Pred); 485 } 486 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 487 SelectInst *SI = cast<SelectInst>(LHS); 488 Value *Cond = SI->getCondition(); 489 Value *TV = SI->getTrueValue(); 490 Value *FV = SI->getFalseValue(); 491 492 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 493 // Does "cmp TV, RHS" simplify? 494 Value *TCmp = simplifyCmpSelTrueCase(Pred, TV, RHS, Cond, Q, MaxRecurse); 495 if (!TCmp) 496 return nullptr; 497 498 // Does "cmp FV, RHS" simplify? 499 Value *FCmp = simplifyCmpSelFalseCase(Pred, FV, RHS, Cond, Q, MaxRecurse); 500 if (!FCmp) 501 return nullptr; 502 503 // If both sides simplified to the same value, then use it as the result of 504 // the original comparison. 505 if (TCmp == FCmp) 506 return TCmp; 507 508 // The remaining cases only make sense if the select condition has the same 509 // type as the result of the comparison, so bail out if this is not so. 510 if (Cond->getType()->isVectorTy() == RHS->getType()->isVectorTy()) 511 return handleOtherCmpSelSimplifications(TCmp, FCmp, Cond, Q, MaxRecurse); 512 513 return nullptr; 514 } 515 516 /// In the case of a binary operation with an operand that is a PHI instruction, 517 /// try to simplify the binop by seeing whether evaluating it on the incoming 518 /// phi values yields the same result for every value. If so returns the common 519 /// value, otherwise returns null. 520 static Value *threadBinOpOverPHI(Instruction::BinaryOps Opcode, Value *LHS, 521 Value *RHS, const SimplifyQuery &Q, 522 unsigned MaxRecurse) { 523 // Recursion is always used, so bail out at once if we already hit the limit. 524 if (!MaxRecurse--) 525 return nullptr; 526 527 PHINode *PI; 528 if (isa<PHINode>(LHS)) { 529 PI = cast<PHINode>(LHS); 530 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 531 if (!valueDominatesPHI(RHS, PI, Q.DT)) 532 return nullptr; 533 } else { 534 assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 535 PI = cast<PHINode>(RHS); 536 // Bail out if LHS and the phi may be mutually interdependent due to a loop. 537 if (!valueDominatesPHI(LHS, PI, Q.DT)) 538 return nullptr; 539 } 540 541 // Evaluate the BinOp on the incoming phi values. 542 Value *CommonValue = nullptr; 543 for (Use &Incoming : PI->incoming_values()) { 544 // If the incoming value is the phi node itself, it can safely be skipped. 545 if (Incoming == PI) 546 continue; 547 Instruction *InTI = PI->getIncomingBlock(Incoming)->getTerminator(); 548 Value *V = PI == LHS 549 ? simplifyBinOp(Opcode, Incoming, RHS, 550 Q.getWithInstruction(InTI), MaxRecurse) 551 : simplifyBinOp(Opcode, LHS, Incoming, 552 Q.getWithInstruction(InTI), MaxRecurse); 553 // If the operation failed to simplify, or simplified to a different value 554 // to previously, then give up. 555 if (!V || (CommonValue && V != CommonValue)) 556 return nullptr; 557 CommonValue = V; 558 } 559 560 return CommonValue; 561 } 562 563 /// In the case of a comparison with a PHI instruction, try to simplify the 564 /// comparison by seeing whether comparing with all of the incoming phi values 565 /// yields the same result every time. If so returns the common result, 566 /// otherwise returns null. 567 static Value *threadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 568 const SimplifyQuery &Q, unsigned MaxRecurse) { 569 // Recursion is always used, so bail out at once if we already hit the limit. 570 if (!MaxRecurse--) 571 return nullptr; 572 573 // Make sure the phi is on the LHS. 574 if (!isa<PHINode>(LHS)) { 575 std::swap(LHS, RHS); 576 Pred = CmpInst::getSwappedPredicate(Pred); 577 } 578 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 579 PHINode *PI = cast<PHINode>(LHS); 580 581 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 582 if (!valueDominatesPHI(RHS, PI, Q.DT)) 583 return nullptr; 584 585 // Evaluate the BinOp on the incoming phi values. 586 Value *CommonValue = nullptr; 587 for (unsigned u = 0, e = PI->getNumIncomingValues(); u < e; ++u) { 588 Value *Incoming = PI->getIncomingValue(u); 589 Instruction *InTI = PI->getIncomingBlock(u)->getTerminator(); 590 // If the incoming value is the phi node itself, it can safely be skipped. 591 if (Incoming == PI) 592 continue; 593 // Change the context instruction to the "edge" that flows into the phi. 594 // This is important because that is where incoming is actually "evaluated" 595 // even though it is used later somewhere else. 596 Value *V = simplifyCmpInst(Pred, Incoming, RHS, Q.getWithInstruction(InTI), 597 MaxRecurse); 598 // If the operation failed to simplify, or simplified to a different value 599 // to previously, then give up. 600 if (!V || (CommonValue && V != CommonValue)) 601 return nullptr; 602 CommonValue = V; 603 } 604 605 return CommonValue; 606 } 607 608 static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode, 609 Value *&Op0, Value *&Op1, 610 const SimplifyQuery &Q) { 611 if (auto *CLHS = dyn_cast<Constant>(Op0)) { 612 if (auto *CRHS = dyn_cast<Constant>(Op1)) { 613 switch (Opcode) { 614 default: 615 break; 616 case Instruction::FAdd: 617 case Instruction::FSub: 618 case Instruction::FMul: 619 case Instruction::FDiv: 620 case Instruction::FRem: 621 if (Q.CxtI != nullptr) 622 return ConstantFoldFPInstOperands(Opcode, CLHS, CRHS, Q.DL, Q.CxtI); 623 } 624 return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL); 625 } 626 627 // Canonicalize the constant to the RHS if this is a commutative operation. 628 if (Instruction::isCommutative(Opcode)) 629 std::swap(Op0, Op1); 630 } 631 return nullptr; 632 } 633 634 /// Given operands for an Add, see if we can fold the result. 635 /// If not, this returns null. 636 static Value *simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 637 const SimplifyQuery &Q, unsigned MaxRecurse) { 638 if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q)) 639 return C; 640 641 // X + poison -> poison 642 if (isa<PoisonValue>(Op1)) 643 return Op1; 644 645 // X + undef -> undef 646 if (Q.isUndefValue(Op1)) 647 return Op1; 648 649 // X + 0 -> X 650 if (match(Op1, m_Zero())) 651 return Op0; 652 653 // If two operands are negative, return 0. 654 if (isKnownNegation(Op0, Op1)) 655 return Constant::getNullValue(Op0->getType()); 656 657 // X + (Y - X) -> Y 658 // (Y - X) + X -> Y 659 // Eg: X + -X -> 0 660 Value *Y = nullptr; 661 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 662 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 663 return Y; 664 665 // X + ~X -> -1 since ~X = -X-1 666 Type *Ty = Op0->getType(); 667 if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0)))) 668 return Constant::getAllOnesValue(Ty); 669 670 // add nsw/nuw (xor Y, signmask), signmask --> Y 671 // The no-wrapping add guarantees that the top bit will be set by the add. 672 // Therefore, the xor must be clearing the already set sign bit of Y. 673 if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) && 674 match(Op0, m_Xor(m_Value(Y), m_SignMask()))) 675 return Y; 676 677 // add nuw %x, -1 -> -1, because %x can only be 0. 678 if (IsNUW && match(Op1, m_AllOnes())) 679 return Op1; // Which is -1. 680 681 /// i1 add -> xor. 682 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 683 if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1)) 684 return V; 685 686 // Try some generic simplifications for associative operations. 687 if (Value *V = 688 simplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, MaxRecurse)) 689 return V; 690 691 // Threading Add over selects and phi nodes is pointless, so don't bother. 692 // Threading over the select in "A + select(cond, B, C)" means evaluating 693 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 694 // only if B and C are equal. If B and C are equal then (since we assume 695 // that operands have already been simplified) "select(cond, B, C)" should 696 // have been simplified to the common value of B and C already. Analysing 697 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 698 // for threading over phi nodes. 699 700 return nullptr; 701 } 702 703 Value *llvm::simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 704 const SimplifyQuery &Query) { 705 return ::simplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit); 706 } 707 708 /// Compute the base pointer and cumulative constant offsets for V. 709 /// 710 /// This strips all constant offsets off of V, leaving it the base pointer, and 711 /// accumulates the total constant offset applied in the returned constant. 712 /// It returns zero if there are no constant offsets applied. 713 /// 714 /// This is very similar to stripAndAccumulateConstantOffsets(), except it 715 /// normalizes the offset bitwidth to the stripped pointer type, not the 716 /// original pointer type. 717 static APInt stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V, 718 bool AllowNonInbounds = false) { 719 assert(V->getType()->isPtrOrPtrVectorTy()); 720 721 APInt Offset = APInt::getZero(DL.getIndexTypeSizeInBits(V->getType())); 722 V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds); 723 // As that strip may trace through `addrspacecast`, need to sext or trunc 724 // the offset calculated. 725 return Offset.sextOrTrunc(DL.getIndexTypeSizeInBits(V->getType())); 726 } 727 728 /// Compute the constant difference between two pointer values. 729 /// If the difference is not a constant, returns zero. 730 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS, 731 Value *RHS) { 732 APInt LHSOffset = stripAndComputeConstantOffsets(DL, LHS); 733 APInt RHSOffset = stripAndComputeConstantOffsets(DL, RHS); 734 735 // If LHS and RHS are not related via constant offsets to the same base 736 // value, there is nothing we can do here. 737 if (LHS != RHS) 738 return nullptr; 739 740 // Otherwise, the difference of LHS - RHS can be computed as: 741 // LHS - RHS 742 // = (LHSOffset + Base) - (RHSOffset + Base) 743 // = LHSOffset - RHSOffset 744 Constant *Res = ConstantInt::get(LHS->getContext(), LHSOffset - RHSOffset); 745 if (auto *VecTy = dyn_cast<VectorType>(LHS->getType())) 746 Res = ConstantVector::getSplat(VecTy->getElementCount(), Res); 747 return Res; 748 } 749 750 /// Test if there is a dominating equivalence condition for the 751 /// two operands. If there is, try to reduce the binary operation 752 /// between the two operands. 753 /// Example: Op0 - Op1 --> 0 when Op0 == Op1 754 static Value *simplifyByDomEq(unsigned Opcode, Value *Op0, Value *Op1, 755 const SimplifyQuery &Q, unsigned MaxRecurse) { 756 // Recursive run it can not get any benefit 757 if (MaxRecurse != RecursionLimit) 758 return nullptr; 759 760 std::optional<bool> Imp = 761 isImpliedByDomCondition(CmpInst::ICMP_EQ, Op0, Op1, Q.CxtI, Q.DL); 762 if (Imp && *Imp) { 763 Type *Ty = Op0->getType(); 764 switch (Opcode) { 765 case Instruction::Sub: 766 case Instruction::Xor: 767 case Instruction::URem: 768 case Instruction::SRem: 769 return Constant::getNullValue(Ty); 770 771 case Instruction::SDiv: 772 case Instruction::UDiv: 773 return ConstantInt::get(Ty, 1); 774 775 case Instruction::And: 776 case Instruction::Or: 777 // Could be either one - choose Op1 since that's more likely a constant. 778 return Op1; 779 default: 780 break; 781 } 782 } 783 return nullptr; 784 } 785 786 /// Given operands for a Sub, see if we can fold the result. 787 /// If not, this returns null. 788 static Value *simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 789 const SimplifyQuery &Q, unsigned MaxRecurse) { 790 if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q)) 791 return C; 792 793 // X - poison -> poison 794 // poison - X -> poison 795 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 796 return PoisonValue::get(Op0->getType()); 797 798 // X - undef -> undef 799 // undef - X -> undef 800 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 801 return UndefValue::get(Op0->getType()); 802 803 // X - 0 -> X 804 if (match(Op1, m_Zero())) 805 return Op0; 806 807 // X - X -> 0 808 if (Op0 == Op1) 809 return Constant::getNullValue(Op0->getType()); 810 811 // Is this a negation? 812 if (match(Op0, m_Zero())) { 813 // 0 - X -> 0 if the sub is NUW. 814 if (IsNUW) 815 return Constant::getNullValue(Op0->getType()); 816 817 KnownBits Known = computeKnownBits(Op1, /* Depth */ 0, Q); 818 if (Known.Zero.isMaxSignedValue()) { 819 // Op1 is either 0 or the minimum signed value. If the sub is NSW, then 820 // Op1 must be 0 because negating the minimum signed value is undefined. 821 if (IsNSW) 822 return Constant::getNullValue(Op0->getType()); 823 824 // 0 - X -> X if X is 0 or the minimum signed value. 825 return Op1; 826 } 827 } 828 829 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 830 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 831 Value *X = nullptr, *Y = nullptr, *Z = Op1; 832 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 833 // See if "V === Y - Z" simplifies. 834 if (Value *V = simplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse - 1)) 835 // It does! Now see if "X + V" simplifies. 836 if (Value *W = simplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse - 1)) { 837 // It does, we successfully reassociated! 838 ++NumReassoc; 839 return W; 840 } 841 // See if "V === X - Z" simplifies. 842 if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1)) 843 // It does! Now see if "Y + V" simplifies. 844 if (Value *W = simplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse - 1)) { 845 // It does, we successfully reassociated! 846 ++NumReassoc; 847 return W; 848 } 849 } 850 851 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 852 // For example, X - (X + 1) -> -1 853 X = Op0; 854 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 855 // See if "V === X - Y" simplifies. 856 if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1)) 857 // It does! Now see if "V - Z" simplifies. 858 if (Value *W = simplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse - 1)) { 859 // It does, we successfully reassociated! 860 ++NumReassoc; 861 return W; 862 } 863 // See if "V === X - Z" simplifies. 864 if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1)) 865 // It does! Now see if "V - Y" simplifies. 866 if (Value *W = simplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse - 1)) { 867 // It does, we successfully reassociated! 868 ++NumReassoc; 869 return W; 870 } 871 } 872 873 // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 874 // For example, X - (X - Y) -> Y. 875 Z = Op0; 876 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 877 // See if "V === Z - X" simplifies. 878 if (Value *V = simplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse - 1)) 879 // It does! Now see if "V + Y" simplifies. 880 if (Value *W = simplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse - 1)) { 881 // It does, we successfully reassociated! 882 ++NumReassoc; 883 return W; 884 } 885 886 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. 887 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && 888 match(Op1, m_Trunc(m_Value(Y)))) 889 if (X->getType() == Y->getType()) 890 // See if "V === X - Y" simplifies. 891 if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1)) 892 // It does! Now see if "trunc V" simplifies. 893 if (Value *W = simplifyCastInst(Instruction::Trunc, V, Op0->getType(), 894 Q, MaxRecurse - 1)) 895 // It does, return the simplified "trunc V". 896 return W; 897 898 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). 899 if (match(Op0, m_PtrToInt(m_Value(X))) && match(Op1, m_PtrToInt(m_Value(Y)))) 900 if (Constant *Result = computePointerDifference(Q.DL, X, Y)) 901 return ConstantFoldIntegerCast(Result, Op0->getType(), /*IsSigned*/ true, 902 Q.DL); 903 904 // i1 sub -> xor. 905 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 906 if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1)) 907 return V; 908 909 // Threading Sub over selects and phi nodes is pointless, so don't bother. 910 // Threading over the select in "A - select(cond, B, C)" means evaluating 911 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 912 // only if B and C are equal. If B and C are equal then (since we assume 913 // that operands have already been simplified) "select(cond, B, C)" should 914 // have been simplified to the common value of B and C already. Analysing 915 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 916 // for threading over phi nodes. 917 918 if (Value *V = simplifyByDomEq(Instruction::Sub, Op0, Op1, Q, MaxRecurse)) 919 return V; 920 921 return nullptr; 922 } 923 924 Value *llvm::simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 925 const SimplifyQuery &Q) { 926 return ::simplifySubInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 927 } 928 929 /// Given operands for a Mul, see if we can fold the result. 930 /// If not, this returns null. 931 static Value *simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 932 const SimplifyQuery &Q, unsigned MaxRecurse) { 933 if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q)) 934 return C; 935 936 // X * poison -> poison 937 if (isa<PoisonValue>(Op1)) 938 return Op1; 939 940 // X * undef -> 0 941 // X * 0 -> 0 942 if (Q.isUndefValue(Op1) || match(Op1, m_Zero())) 943 return Constant::getNullValue(Op0->getType()); 944 945 // X * 1 -> X 946 if (match(Op1, m_One())) 947 return Op0; 948 949 // (X / Y) * Y -> X if the division is exact. 950 Value *X = nullptr; 951 if (Q.IIQ.UseInstrInfo && 952 (match(Op0, 953 m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y 954 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))) // Y * (X / Y) 955 return X; 956 957 if (Op0->getType()->isIntOrIntVectorTy(1)) { 958 // mul i1 nsw is a special-case because -1 * -1 is poison (+1 is not 959 // representable). All other cases reduce to 0, so just return 0. 960 if (IsNSW) 961 return ConstantInt::getNullValue(Op0->getType()); 962 963 // Treat "mul i1" as "and i1". 964 if (MaxRecurse) 965 if (Value *V = simplifyAndInst(Op0, Op1, Q, MaxRecurse - 1)) 966 return V; 967 } 968 969 // Try some generic simplifications for associative operations. 970 if (Value *V = 971 simplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 972 return V; 973 974 // Mul distributes over Add. Try some generic simplifications based on this. 975 if (Value *V = expandCommutativeBinOp(Instruction::Mul, Op0, Op1, 976 Instruction::Add, Q, MaxRecurse)) 977 return V; 978 979 // If the operation is with the result of a select instruction, check whether 980 // operating on either branch of the select always yields the same value. 981 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 982 if (Value *V = 983 threadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 984 return V; 985 986 // If the operation is with the result of a phi instruction, check whether 987 // operating on all incoming values of the phi always yields the same value. 988 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 989 if (Value *V = 990 threadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 991 return V; 992 993 return nullptr; 994 } 995 996 Value *llvm::simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 997 const SimplifyQuery &Q) { 998 return ::simplifyMulInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 999 } 1000 1001 /// Given a predicate and two operands, return true if the comparison is true. 1002 /// This is a helper for div/rem simplification where we return some other value 1003 /// when we can prove a relationship between the operands. 1004 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS, 1005 const SimplifyQuery &Q, unsigned MaxRecurse) { 1006 Value *V = simplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse); 1007 Constant *C = dyn_cast_or_null<Constant>(V); 1008 return (C && C->isAllOnesValue()); 1009 } 1010 1011 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer 1012 /// to simplify X % Y to X. 1013 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q, 1014 unsigned MaxRecurse, bool IsSigned) { 1015 // Recursion is always used, so bail out at once if we already hit the limit. 1016 if (!MaxRecurse--) 1017 return false; 1018 1019 if (IsSigned) { 1020 // (X srem Y) sdiv Y --> 0 1021 if (match(X, m_SRem(m_Value(), m_Specific(Y)))) 1022 return true; 1023 1024 // |X| / |Y| --> 0 1025 // 1026 // We require that 1 operand is a simple constant. That could be extended to 1027 // 2 variables if we computed the sign bit for each. 1028 // 1029 // Make sure that a constant is not the minimum signed value because taking 1030 // the abs() of that is undefined. 1031 Type *Ty = X->getType(); 1032 const APInt *C; 1033 if (match(X, m_APInt(C)) && !C->isMinSignedValue()) { 1034 // Is the variable divisor magnitude always greater than the constant 1035 // dividend magnitude? 1036 // |Y| > |C| --> Y < -abs(C) or Y > abs(C) 1037 Constant *PosDividendC = ConstantInt::get(Ty, C->abs()); 1038 Constant *NegDividendC = ConstantInt::get(Ty, -C->abs()); 1039 if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) || 1040 isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse)) 1041 return true; 1042 } 1043 if (match(Y, m_APInt(C))) { 1044 // Special-case: we can't take the abs() of a minimum signed value. If 1045 // that's the divisor, then all we have to do is prove that the dividend 1046 // is also not the minimum signed value. 1047 if (C->isMinSignedValue()) 1048 return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse); 1049 1050 // Is the variable dividend magnitude always less than the constant 1051 // divisor magnitude? 1052 // |X| < |C| --> X > -abs(C) and X < abs(C) 1053 Constant *PosDivisorC = ConstantInt::get(Ty, C->abs()); 1054 Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs()); 1055 if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) && 1056 isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse)) 1057 return true; 1058 } 1059 return false; 1060 } 1061 1062 // IsSigned == false. 1063 1064 // Is the unsigned dividend known to be less than a constant divisor? 1065 // TODO: Convert this (and above) to range analysis 1066 // ("computeConstantRangeIncludingKnownBits")? 1067 const APInt *C; 1068 if (match(Y, m_APInt(C)) && 1069 computeKnownBits(X, /* Depth */ 0, Q).getMaxValue().ult(*C)) 1070 return true; 1071 1072 // Try again for any divisor: 1073 // Is the dividend unsigned less than the divisor? 1074 return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse); 1075 } 1076 1077 /// Check for common or similar folds of integer division or integer remainder. 1078 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem). 1079 static Value *simplifyDivRem(Instruction::BinaryOps Opcode, Value *Op0, 1080 Value *Op1, const SimplifyQuery &Q, 1081 unsigned MaxRecurse) { 1082 bool IsDiv = (Opcode == Instruction::SDiv || Opcode == Instruction::UDiv); 1083 bool IsSigned = (Opcode == Instruction::SDiv || Opcode == Instruction::SRem); 1084 1085 Type *Ty = Op0->getType(); 1086 1087 // X / undef -> poison 1088 // X % undef -> poison 1089 if (Q.isUndefValue(Op1) || isa<PoisonValue>(Op1)) 1090 return PoisonValue::get(Ty); 1091 1092 // X / 0 -> poison 1093 // X % 0 -> poison 1094 // We don't need to preserve faults! 1095 if (match(Op1, m_Zero())) 1096 return PoisonValue::get(Ty); 1097 1098 // poison / X -> poison 1099 // poison % X -> poison 1100 if (isa<PoisonValue>(Op0)) 1101 return Op0; 1102 1103 // undef / X -> 0 1104 // undef % X -> 0 1105 if (Q.isUndefValue(Op0)) 1106 return Constant::getNullValue(Ty); 1107 1108 // 0 / X -> 0 1109 // 0 % X -> 0 1110 if (match(Op0, m_Zero())) 1111 return Constant::getNullValue(Op0->getType()); 1112 1113 // X / X -> 1 1114 // X % X -> 0 1115 if (Op0 == Op1) 1116 return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty); 1117 1118 KnownBits Known = computeKnownBits(Op1, /* Depth */ 0, Q); 1119 // X / 0 -> poison 1120 // X % 0 -> poison 1121 // If the divisor is known to be zero, just return poison. This can happen in 1122 // some cases where its provable indirectly the denominator is zero but it's 1123 // not trivially simplifiable (i.e known zero through a phi node). 1124 if (Known.isZero()) 1125 return PoisonValue::get(Ty); 1126 1127 // X / 1 -> X 1128 // X % 1 -> 0 1129 // If the divisor can only be zero or one, we can't have division-by-zero 1130 // or remainder-by-zero, so assume the divisor is 1. 1131 // e.g. 1, zext (i8 X), sdiv X (Y and 1) 1132 if (Known.countMinLeadingZeros() == Known.getBitWidth() - 1) 1133 return IsDiv ? Op0 : Constant::getNullValue(Ty); 1134 1135 // If X * Y does not overflow, then: 1136 // X * Y / Y -> X 1137 // X * Y % Y -> 0 1138 Value *X; 1139 if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) { 1140 auto *Mul = cast<OverflowingBinaryOperator>(Op0); 1141 // The multiplication can't overflow if it is defined not to, or if 1142 // X == A / Y for some A. 1143 if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) || 1144 (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)) || 1145 (IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) || 1146 (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) { 1147 return IsDiv ? X : Constant::getNullValue(Op0->getType()); 1148 } 1149 } 1150 1151 if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned)) 1152 return IsDiv ? Constant::getNullValue(Op0->getType()) : Op0; 1153 1154 if (Value *V = simplifyByDomEq(Opcode, Op0, Op1, Q, MaxRecurse)) 1155 return V; 1156 1157 // If the operation is with the result of a select instruction, check whether 1158 // operating on either branch of the select always yields the same value. 1159 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1160 if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1161 return V; 1162 1163 // If the operation is with the result of a phi instruction, check whether 1164 // operating on all incoming values of the phi always yields the same value. 1165 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1166 if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1167 return V; 1168 1169 return nullptr; 1170 } 1171 1172 /// These are simplifications common to SDiv and UDiv. 1173 static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1174 bool IsExact, const SimplifyQuery &Q, 1175 unsigned MaxRecurse) { 1176 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1177 return C; 1178 1179 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse)) 1180 return V; 1181 1182 const APInt *DivC; 1183 if (IsExact && match(Op1, m_APInt(DivC))) { 1184 // If this is an exact divide by a constant, then the dividend (Op0) must 1185 // have at least as many trailing zeros as the divisor to divide evenly. If 1186 // it has less trailing zeros, then the result must be poison. 1187 if (DivC->countr_zero()) { 1188 KnownBits KnownOp0 = computeKnownBits(Op0, /* Depth */ 0, Q); 1189 if (KnownOp0.countMaxTrailingZeros() < DivC->countr_zero()) 1190 return PoisonValue::get(Op0->getType()); 1191 } 1192 1193 // udiv exact (mul nsw X, C), C --> X 1194 // sdiv exact (mul nuw X, C), C --> X 1195 // where C is not a power of 2. 1196 Value *X; 1197 if (!DivC->isPowerOf2() && 1198 (Opcode == Instruction::UDiv 1199 ? match(Op0, m_NSWMul(m_Value(X), m_Specific(Op1))) 1200 : match(Op0, m_NUWMul(m_Value(X), m_Specific(Op1))))) 1201 return X; 1202 } 1203 1204 return nullptr; 1205 } 1206 1207 /// These are simplifications common to SRem and URem. 1208 static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1209 const SimplifyQuery &Q, unsigned MaxRecurse) { 1210 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1211 return C; 1212 1213 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse)) 1214 return V; 1215 1216 // (X << Y) % X -> 0 1217 if (Q.IIQ.UseInstrInfo) { 1218 if ((Opcode == Instruction::SRem && 1219 match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) || 1220 (Opcode == Instruction::URem && 1221 match(Op0, m_NUWShl(m_Specific(Op1), m_Value())))) 1222 return Constant::getNullValue(Op0->getType()); 1223 1224 const APInt *C0; 1225 if (match(Op1, m_APInt(C0))) { 1226 // (srem (mul nsw X, C1), C0) -> 0 if C1 s% C0 == 0 1227 // (urem (mul nuw X, C1), C0) -> 0 if C1 u% C0 == 0 1228 if (Opcode == Instruction::SRem 1229 ? match(Op0, 1230 m_NSWMul(m_Value(), m_CheckedInt([C0](const APInt &C) { 1231 return C.srem(*C0).isZero(); 1232 }))) 1233 : match(Op0, 1234 m_NUWMul(m_Value(), m_CheckedInt([C0](const APInt &C) { 1235 return C.urem(*C0).isZero(); 1236 })))) 1237 return Constant::getNullValue(Op0->getType()); 1238 } 1239 } 1240 return nullptr; 1241 } 1242 1243 /// Given operands for an SDiv, see if we can fold the result. 1244 /// If not, this returns null. 1245 static Value *simplifySDivInst(Value *Op0, Value *Op1, bool IsExact, 1246 const SimplifyQuery &Q, unsigned MaxRecurse) { 1247 // If two operands are negated and no signed overflow, return -1. 1248 if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true)) 1249 return Constant::getAllOnesValue(Op0->getType()); 1250 1251 return simplifyDiv(Instruction::SDiv, Op0, Op1, IsExact, Q, MaxRecurse); 1252 } 1253 1254 Value *llvm::simplifySDivInst(Value *Op0, Value *Op1, bool IsExact, 1255 const SimplifyQuery &Q) { 1256 return ::simplifySDivInst(Op0, Op1, IsExact, Q, RecursionLimit); 1257 } 1258 1259 /// Given operands for a UDiv, see if we can fold the result. 1260 /// If not, this returns null. 1261 static Value *simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact, 1262 const SimplifyQuery &Q, unsigned MaxRecurse) { 1263 return simplifyDiv(Instruction::UDiv, Op0, Op1, IsExact, Q, MaxRecurse); 1264 } 1265 1266 Value *llvm::simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact, 1267 const SimplifyQuery &Q) { 1268 return ::simplifyUDivInst(Op0, Op1, IsExact, Q, RecursionLimit); 1269 } 1270 1271 /// Given operands for an SRem, see if we can fold the result. 1272 /// If not, this returns null. 1273 static Value *simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1274 unsigned MaxRecurse) { 1275 // If the divisor is 0, the result is undefined, so assume the divisor is -1. 1276 // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0 1277 Value *X; 1278 if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) 1279 return ConstantInt::getNullValue(Op0->getType()); 1280 1281 // If the two operands are negated, return 0. 1282 if (isKnownNegation(Op0, Op1)) 1283 return ConstantInt::getNullValue(Op0->getType()); 1284 1285 return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse); 1286 } 1287 1288 Value *llvm::simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1289 return ::simplifySRemInst(Op0, Op1, Q, RecursionLimit); 1290 } 1291 1292 /// Given operands for a URem, see if we can fold the result. 1293 /// If not, this returns null. 1294 static Value *simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1295 unsigned MaxRecurse) { 1296 return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse); 1297 } 1298 1299 Value *llvm::simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1300 return ::simplifyURemInst(Op0, Op1, Q, RecursionLimit); 1301 } 1302 1303 /// Returns true if a shift by \c Amount always yields poison. 1304 static bool isPoisonShift(Value *Amount, const SimplifyQuery &Q) { 1305 Constant *C = dyn_cast<Constant>(Amount); 1306 if (!C) 1307 return false; 1308 1309 // X shift by undef -> poison because it may shift by the bitwidth. 1310 if (Q.isUndefValue(C)) 1311 return true; 1312 1313 // Shifting by the bitwidth or more is poison. This covers scalars and 1314 // fixed/scalable vectors with splat constants. 1315 const APInt *AmountC; 1316 if (match(C, m_APInt(AmountC)) && AmountC->uge(AmountC->getBitWidth())) 1317 return true; 1318 1319 // Try harder for fixed-length vectors: 1320 // If all lanes of a vector shift are poison, the whole shift is poison. 1321 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) { 1322 for (unsigned I = 0, 1323 E = cast<FixedVectorType>(C->getType())->getNumElements(); 1324 I != E; ++I) 1325 if (!isPoisonShift(C->getAggregateElement(I), Q)) 1326 return false; 1327 return true; 1328 } 1329 1330 return false; 1331 } 1332 1333 /// Given operands for an Shl, LShr or AShr, see if we can fold the result. 1334 /// If not, this returns null. 1335 static Value *simplifyShift(Instruction::BinaryOps Opcode, Value *Op0, 1336 Value *Op1, bool IsNSW, const SimplifyQuery &Q, 1337 unsigned MaxRecurse) { 1338 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1339 return C; 1340 1341 // poison shift by X -> poison 1342 if (isa<PoisonValue>(Op0)) 1343 return Op0; 1344 1345 // 0 shift by X -> 0 1346 if (match(Op0, m_Zero())) 1347 return Constant::getNullValue(Op0->getType()); 1348 1349 // X shift by 0 -> X 1350 // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones 1351 // would be poison. 1352 Value *X; 1353 if (match(Op1, m_Zero()) || 1354 (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) 1355 return Op0; 1356 1357 // Fold undefined shifts. 1358 if (isPoisonShift(Op1, Q)) 1359 return PoisonValue::get(Op0->getType()); 1360 1361 // If the operation is with the result of a select instruction, check whether 1362 // operating on either branch of the select always yields the same value. 1363 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1364 if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1365 return V; 1366 1367 // If the operation is with the result of a phi instruction, check whether 1368 // operating on all incoming values of the phi always yields the same value. 1369 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1370 if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1371 return V; 1372 1373 // If any bits in the shift amount make that value greater than or equal to 1374 // the number of bits in the type, the shift is undefined. 1375 KnownBits KnownAmt = computeKnownBits(Op1, /* Depth */ 0, Q); 1376 if (KnownAmt.getMinValue().uge(KnownAmt.getBitWidth())) 1377 return PoisonValue::get(Op0->getType()); 1378 1379 // If all valid bits in the shift amount are known zero, the first operand is 1380 // unchanged. 1381 unsigned NumValidShiftBits = Log2_32_Ceil(KnownAmt.getBitWidth()); 1382 if (KnownAmt.countMinTrailingZeros() >= NumValidShiftBits) 1383 return Op0; 1384 1385 // Check for nsw shl leading to a poison value. 1386 if (IsNSW) { 1387 assert(Opcode == Instruction::Shl && "Expected shl for nsw instruction"); 1388 KnownBits KnownVal = computeKnownBits(Op0, /* Depth */ 0, Q); 1389 KnownBits KnownShl = KnownBits::shl(KnownVal, KnownAmt); 1390 1391 if (KnownVal.Zero.isSignBitSet()) 1392 KnownShl.Zero.setSignBit(); 1393 if (KnownVal.One.isSignBitSet()) 1394 KnownShl.One.setSignBit(); 1395 1396 if (KnownShl.hasConflict()) 1397 return PoisonValue::get(Op0->getType()); 1398 } 1399 1400 return nullptr; 1401 } 1402 1403 /// Given operands for an LShr or AShr, see if we can fold the result. If not, 1404 /// this returns null. 1405 static Value *simplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0, 1406 Value *Op1, bool IsExact, 1407 const SimplifyQuery &Q, unsigned MaxRecurse) { 1408 if (Value *V = 1409 simplifyShift(Opcode, Op0, Op1, /*IsNSW*/ false, Q, MaxRecurse)) 1410 return V; 1411 1412 // X >> X -> 0 1413 if (Op0 == Op1) 1414 return Constant::getNullValue(Op0->getType()); 1415 1416 // undef >> X -> 0 1417 // undef >> X -> undef (if it's exact) 1418 if (Q.isUndefValue(Op0)) 1419 return IsExact ? Op0 : Constant::getNullValue(Op0->getType()); 1420 1421 // The low bit cannot be shifted out of an exact shift if it is set. 1422 // TODO: Generalize by counting trailing zeros (see fold for exact division). 1423 if (IsExact) { 1424 KnownBits Op0Known = computeKnownBits(Op0, /* Depth */ 0, Q); 1425 if (Op0Known.One[0]) 1426 return Op0; 1427 } 1428 1429 return nullptr; 1430 } 1431 1432 /// Given operands for an Shl, see if we can fold the result. 1433 /// If not, this returns null. 1434 static Value *simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 1435 const SimplifyQuery &Q, unsigned MaxRecurse) { 1436 if (Value *V = 1437 simplifyShift(Instruction::Shl, Op0, Op1, IsNSW, Q, MaxRecurse)) 1438 return V; 1439 1440 Type *Ty = Op0->getType(); 1441 // undef << X -> 0 1442 // undef << X -> undef if (if it's NSW/NUW) 1443 if (Q.isUndefValue(Op0)) 1444 return IsNSW || IsNUW ? Op0 : Constant::getNullValue(Ty); 1445 1446 // (X >> A) << A -> X 1447 Value *X; 1448 if (Q.IIQ.UseInstrInfo && 1449 match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) 1450 return X; 1451 1452 // shl nuw i8 C, %x -> C iff C has sign bit set. 1453 if (IsNUW && match(Op0, m_Negative())) 1454 return Op0; 1455 // NOTE: could use computeKnownBits() / LazyValueInfo, 1456 // but the cost-benefit analysis suggests it isn't worth it. 1457 1458 // "nuw" guarantees that only zeros are shifted out, and "nsw" guarantees 1459 // that the sign-bit does not change, so the only input that does not 1460 // produce poison is 0, and "0 << (bitwidth-1) --> 0". 1461 if (IsNSW && IsNUW && 1462 match(Op1, m_SpecificInt(Ty->getScalarSizeInBits() - 1))) 1463 return Constant::getNullValue(Ty); 1464 1465 return nullptr; 1466 } 1467 1468 Value *llvm::simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 1469 const SimplifyQuery &Q) { 1470 return ::simplifyShlInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 1471 } 1472 1473 /// Given operands for an LShr, see if we can fold the result. 1474 /// If not, this returns null. 1475 static Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, 1476 const SimplifyQuery &Q, unsigned MaxRecurse) { 1477 if (Value *V = simplifyRightShift(Instruction::LShr, Op0, Op1, IsExact, Q, 1478 MaxRecurse)) 1479 return V; 1480 1481 // (X << A) >> A -> X 1482 Value *X; 1483 if (Q.IIQ.UseInstrInfo && match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1)))) 1484 return X; 1485 1486 // ((X << A) | Y) >> A -> X if effective width of Y is not larger than A. 1487 // We can return X as we do in the above case since OR alters no bits in X. 1488 // SimplifyDemandedBits in InstCombine can do more general optimization for 1489 // bit manipulation. This pattern aims to provide opportunities for other 1490 // optimizers by supporting a simple but common case in InstSimplify. 1491 Value *Y; 1492 const APInt *ShRAmt, *ShLAmt; 1493 if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(ShRAmt)) && 1494 match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) && 1495 *ShRAmt == *ShLAmt) { 1496 const KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 1497 const unsigned EffWidthY = YKnown.countMaxActiveBits(); 1498 if (ShRAmt->uge(EffWidthY)) 1499 return X; 1500 } 1501 1502 return nullptr; 1503 } 1504 1505 Value *llvm::simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, 1506 const SimplifyQuery &Q) { 1507 return ::simplifyLShrInst(Op0, Op1, IsExact, Q, RecursionLimit); 1508 } 1509 1510 /// Given operands for an AShr, see if we can fold the result. 1511 /// If not, this returns null. 1512 static Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, 1513 const SimplifyQuery &Q, unsigned MaxRecurse) { 1514 if (Value *V = simplifyRightShift(Instruction::AShr, Op0, Op1, IsExact, Q, 1515 MaxRecurse)) 1516 return V; 1517 1518 // -1 >>a X --> -1 1519 // (-1 << X) a>> X --> -1 1520 // We could return the original -1 constant to preserve poison elements. 1521 if (match(Op0, m_AllOnes()) || 1522 match(Op0, m_Shl(m_AllOnes(), m_Specific(Op1)))) 1523 return Constant::getAllOnesValue(Op0->getType()); 1524 1525 // (X << A) >> A -> X 1526 Value *X; 1527 if (Q.IIQ.UseInstrInfo && match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1)))) 1528 return X; 1529 1530 // Arithmetic shifting an all-sign-bit value is a no-op. 1531 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1532 if (NumSignBits == Op0->getType()->getScalarSizeInBits()) 1533 return Op0; 1534 1535 return nullptr; 1536 } 1537 1538 Value *llvm::simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, 1539 const SimplifyQuery &Q) { 1540 return ::simplifyAShrInst(Op0, Op1, IsExact, Q, RecursionLimit); 1541 } 1542 1543 /// Commuted variants are assumed to be handled by calling this function again 1544 /// with the parameters swapped. 1545 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp, 1546 ICmpInst *UnsignedICmp, bool IsAnd, 1547 const SimplifyQuery &Q) { 1548 Value *X, *Y; 1549 1550 ICmpInst::Predicate EqPred; 1551 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) || 1552 !ICmpInst::isEquality(EqPred)) 1553 return nullptr; 1554 1555 ICmpInst::Predicate UnsignedPred; 1556 1557 Value *A, *B; 1558 // Y = (A - B); 1559 if (match(Y, m_Sub(m_Value(A), m_Value(B)))) { 1560 if (match(UnsignedICmp, 1561 m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) && 1562 ICmpInst::isUnsigned(UnsignedPred)) { 1563 // A >=/<= B || (A - B) != 0 <--> true 1564 if ((UnsignedPred == ICmpInst::ICMP_UGE || 1565 UnsignedPred == ICmpInst::ICMP_ULE) && 1566 EqPred == ICmpInst::ICMP_NE && !IsAnd) 1567 return ConstantInt::getTrue(UnsignedICmp->getType()); 1568 // A </> B && (A - B) == 0 <--> false 1569 if ((UnsignedPred == ICmpInst::ICMP_ULT || 1570 UnsignedPred == ICmpInst::ICMP_UGT) && 1571 EqPred == ICmpInst::ICMP_EQ && IsAnd) 1572 return ConstantInt::getFalse(UnsignedICmp->getType()); 1573 1574 // A </> B && (A - B) != 0 <--> A </> B 1575 // A </> B || (A - B) != 0 <--> (A - B) != 0 1576 if (EqPred == ICmpInst::ICMP_NE && (UnsignedPred == ICmpInst::ICMP_ULT || 1577 UnsignedPred == ICmpInst::ICMP_UGT)) 1578 return IsAnd ? UnsignedICmp : ZeroICmp; 1579 1580 // A <=/>= B && (A - B) == 0 <--> (A - B) == 0 1581 // A <=/>= B || (A - B) == 0 <--> A <=/>= B 1582 if (EqPred == ICmpInst::ICMP_EQ && (UnsignedPred == ICmpInst::ICMP_ULE || 1583 UnsignedPred == ICmpInst::ICMP_UGE)) 1584 return IsAnd ? ZeroICmp : UnsignedICmp; 1585 } 1586 1587 // Given Y = (A - B) 1588 // Y >= A && Y != 0 --> Y >= A iff B != 0 1589 // Y < A || Y == 0 --> Y < A iff B != 0 1590 if (match(UnsignedICmp, 1591 m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) { 1592 if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd && 1593 EqPred == ICmpInst::ICMP_NE && isKnownNonZero(B, Q)) 1594 return UnsignedICmp; 1595 if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd && 1596 EqPred == ICmpInst::ICMP_EQ && isKnownNonZero(B, Q)) 1597 return UnsignedICmp; 1598 } 1599 } 1600 1601 if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) && 1602 ICmpInst::isUnsigned(UnsignedPred)) 1603 ; 1604 else if (match(UnsignedICmp, 1605 m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) && 1606 ICmpInst::isUnsigned(UnsignedPred)) 1607 UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); 1608 else 1609 return nullptr; 1610 1611 // X > Y && Y == 0 --> Y == 0 iff X != 0 1612 // X > Y || Y == 0 --> X > Y iff X != 0 1613 if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ && 1614 isKnownNonZero(X, Q)) 1615 return IsAnd ? ZeroICmp : UnsignedICmp; 1616 1617 // X <= Y && Y != 0 --> X <= Y iff X != 0 1618 // X <= Y || Y != 0 --> Y != 0 iff X != 0 1619 if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE && 1620 isKnownNonZero(X, Q)) 1621 return IsAnd ? UnsignedICmp : ZeroICmp; 1622 1623 // The transforms below here are expected to be handled more generally with 1624 // simplifyAndOrOfICmpsWithLimitConst() or in InstCombine's 1625 // foldAndOrOfICmpsWithConstEq(). If we are looking to trim optimizer overlap, 1626 // these are candidates for removal. 1627 1628 // X < Y && Y != 0 --> X < Y 1629 // X < Y || Y != 0 --> Y != 0 1630 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE) 1631 return IsAnd ? UnsignedICmp : ZeroICmp; 1632 1633 // X >= Y && Y == 0 --> Y == 0 1634 // X >= Y || Y == 0 --> X >= Y 1635 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ) 1636 return IsAnd ? ZeroICmp : UnsignedICmp; 1637 1638 // X < Y && Y == 0 --> false 1639 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ && 1640 IsAnd) 1641 return getFalse(UnsignedICmp->getType()); 1642 1643 // X >= Y || Y != 0 --> true 1644 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE && 1645 !IsAnd) 1646 return getTrue(UnsignedICmp->getType()); 1647 1648 return nullptr; 1649 } 1650 1651 /// Test if a pair of compares with a shared operand and 2 constants has an 1652 /// empty set intersection, full set union, or if one compare is a superset of 1653 /// the other. 1654 static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1, 1655 bool IsAnd) { 1656 // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)). 1657 if (Cmp0->getOperand(0) != Cmp1->getOperand(0)) 1658 return nullptr; 1659 1660 const APInt *C0, *C1; 1661 if (!match(Cmp0->getOperand(1), m_APInt(C0)) || 1662 !match(Cmp1->getOperand(1), m_APInt(C1))) 1663 return nullptr; 1664 1665 auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0); 1666 auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1); 1667 1668 // For and-of-compares, check if the intersection is empty: 1669 // (icmp X, C0) && (icmp X, C1) --> empty set --> false 1670 if (IsAnd && Range0.intersectWith(Range1).isEmptySet()) 1671 return getFalse(Cmp0->getType()); 1672 1673 // For or-of-compares, check if the union is full: 1674 // (icmp X, C0) || (icmp X, C1) --> full set --> true 1675 if (!IsAnd && Range0.unionWith(Range1).isFullSet()) 1676 return getTrue(Cmp0->getType()); 1677 1678 // Is one range a superset of the other? 1679 // If this is and-of-compares, take the smaller set: 1680 // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42 1681 // If this is or-of-compares, take the larger set: 1682 // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4 1683 if (Range0.contains(Range1)) 1684 return IsAnd ? Cmp1 : Cmp0; 1685 if (Range1.contains(Range0)) 1686 return IsAnd ? Cmp0 : Cmp1; 1687 1688 return nullptr; 1689 } 1690 1691 static Value *simplifyAndOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1692 const InstrInfoQuery &IIQ) { 1693 // (icmp (add V, C0), C1) & (icmp V, C0) 1694 ICmpInst::Predicate Pred0, Pred1; 1695 const APInt *C0, *C1; 1696 Value *V; 1697 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1698 return nullptr; 1699 1700 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1701 return nullptr; 1702 1703 auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0)); 1704 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1705 return nullptr; 1706 1707 Type *ITy = Op0->getType(); 1708 bool IsNSW = IIQ.hasNoSignedWrap(AddInst); 1709 bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst); 1710 1711 const APInt Delta = *C1 - *C0; 1712 if (C0->isStrictlyPositive()) { 1713 if (Delta == 2) { 1714 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT) 1715 return getFalse(ITy); 1716 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && IsNSW) 1717 return getFalse(ITy); 1718 } 1719 if (Delta == 1) { 1720 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT) 1721 return getFalse(ITy); 1722 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && IsNSW) 1723 return getFalse(ITy); 1724 } 1725 } 1726 if (C0->getBoolValue() && IsNUW) { 1727 if (Delta == 2) 1728 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT) 1729 return getFalse(ITy); 1730 if (Delta == 1) 1731 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT) 1732 return getFalse(ITy); 1733 } 1734 1735 return nullptr; 1736 } 1737 1738 /// Try to simplify and/or of icmp with ctpop intrinsic. 1739 static Value *simplifyAndOrOfICmpsWithCtpop(ICmpInst *Cmp0, ICmpInst *Cmp1, 1740 bool IsAnd) { 1741 ICmpInst::Predicate Pred0, Pred1; 1742 Value *X; 1743 const APInt *C; 1744 if (!match(Cmp0, m_ICmp(Pred0, m_Intrinsic<Intrinsic::ctpop>(m_Value(X)), 1745 m_APInt(C))) || 1746 !match(Cmp1, m_ICmp(Pred1, m_Specific(X), m_ZeroInt())) || C->isZero()) 1747 return nullptr; 1748 1749 // (ctpop(X) == C) || (X != 0) --> X != 0 where C > 0 1750 if (!IsAnd && Pred0 == ICmpInst::ICMP_EQ && Pred1 == ICmpInst::ICMP_NE) 1751 return Cmp1; 1752 // (ctpop(X) != C) && (X == 0) --> X == 0 where C > 0 1753 if (IsAnd && Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_EQ) 1754 return Cmp1; 1755 1756 return nullptr; 1757 } 1758 1759 static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1760 const SimplifyQuery &Q) { 1761 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true, Q)) 1762 return X; 1763 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true, Q)) 1764 return X; 1765 1766 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true)) 1767 return X; 1768 1769 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, true)) 1770 return X; 1771 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, true)) 1772 return X; 1773 1774 if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1775 return X; 1776 if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1777 return X; 1778 1779 return nullptr; 1780 } 1781 1782 static Value *simplifyOrOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1783 const InstrInfoQuery &IIQ) { 1784 // (icmp (add V, C0), C1) | (icmp V, C0) 1785 ICmpInst::Predicate Pred0, Pred1; 1786 const APInt *C0, *C1; 1787 Value *V; 1788 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1789 return nullptr; 1790 1791 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1792 return nullptr; 1793 1794 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0)); 1795 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1796 return nullptr; 1797 1798 Type *ITy = Op0->getType(); 1799 bool IsNSW = IIQ.hasNoSignedWrap(AddInst); 1800 bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst); 1801 1802 const APInt Delta = *C1 - *C0; 1803 if (C0->isStrictlyPositive()) { 1804 if (Delta == 2) { 1805 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE) 1806 return getTrue(ITy); 1807 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && IsNSW) 1808 return getTrue(ITy); 1809 } 1810 if (Delta == 1) { 1811 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE) 1812 return getTrue(ITy); 1813 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && IsNSW) 1814 return getTrue(ITy); 1815 } 1816 } 1817 if (C0->getBoolValue() && IsNUW) { 1818 if (Delta == 2) 1819 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE) 1820 return getTrue(ITy); 1821 if (Delta == 1) 1822 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE) 1823 return getTrue(ITy); 1824 } 1825 1826 return nullptr; 1827 } 1828 1829 static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1830 const SimplifyQuery &Q) { 1831 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false, Q)) 1832 return X; 1833 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false, Q)) 1834 return X; 1835 1836 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false)) 1837 return X; 1838 1839 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, false)) 1840 return X; 1841 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, false)) 1842 return X; 1843 1844 if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1845 return X; 1846 if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1847 return X; 1848 1849 return nullptr; 1850 } 1851 1852 static Value *simplifyAndOrOfFCmps(const SimplifyQuery &Q, FCmpInst *LHS, 1853 FCmpInst *RHS, bool IsAnd) { 1854 Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); 1855 Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); 1856 if (LHS0->getType() != RHS0->getType()) 1857 return nullptr; 1858 1859 FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); 1860 auto AbsOrSelfLHS0 = m_CombineOr(m_Specific(LHS0), m_FAbs(m_Specific(LHS0))); 1861 if ((PredL == FCmpInst::FCMP_ORD || PredL == FCmpInst::FCMP_UNO) && 1862 ((FCmpInst::isOrdered(PredR) && IsAnd) || 1863 (FCmpInst::isUnordered(PredR) && !IsAnd))) { 1864 // (fcmp ord X, 0) & (fcmp o** X/abs(X), Y) --> fcmp o** X/abs(X), Y 1865 // (fcmp uno X, 0) & (fcmp o** X/abs(X), Y) --> false 1866 // (fcmp uno X, 0) | (fcmp u** X/abs(X), Y) --> fcmp u** X/abs(X), Y 1867 // (fcmp ord X, 0) | (fcmp u** X/abs(X), Y) --> true 1868 if ((match(RHS0, AbsOrSelfLHS0) || match(RHS1, AbsOrSelfLHS0)) && 1869 match(LHS1, m_PosZeroFP())) 1870 return FCmpInst::isOrdered(PredL) == FCmpInst::isOrdered(PredR) 1871 ? static_cast<Value *>(RHS) 1872 : ConstantInt::getBool(LHS->getType(), !IsAnd); 1873 } 1874 1875 auto AbsOrSelfRHS0 = m_CombineOr(m_Specific(RHS0), m_FAbs(m_Specific(RHS0))); 1876 if ((PredR == FCmpInst::FCMP_ORD || PredR == FCmpInst::FCMP_UNO) && 1877 ((FCmpInst::isOrdered(PredL) && IsAnd) || 1878 (FCmpInst::isUnordered(PredL) && !IsAnd))) { 1879 // (fcmp o** X/abs(X), Y) & (fcmp ord X, 0) --> fcmp o** X/abs(X), Y 1880 // (fcmp o** X/abs(X), Y) & (fcmp uno X, 0) --> false 1881 // (fcmp u** X/abs(X), Y) | (fcmp uno X, 0) --> fcmp u** X/abs(X), Y 1882 // (fcmp u** X/abs(X), Y) | (fcmp ord X, 0) --> true 1883 if ((match(LHS0, AbsOrSelfRHS0) || match(LHS1, AbsOrSelfRHS0)) && 1884 match(RHS1, m_PosZeroFP())) 1885 return FCmpInst::isOrdered(PredL) == FCmpInst::isOrdered(PredR) 1886 ? static_cast<Value *>(LHS) 1887 : ConstantInt::getBool(LHS->getType(), !IsAnd); 1888 } 1889 1890 return nullptr; 1891 } 1892 1893 static Value *simplifyAndOrOfCmps(const SimplifyQuery &Q, Value *Op0, 1894 Value *Op1, bool IsAnd) { 1895 // Look through casts of the 'and' operands to find compares. 1896 auto *Cast0 = dyn_cast<CastInst>(Op0); 1897 auto *Cast1 = dyn_cast<CastInst>(Op1); 1898 if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() && 1899 Cast0->getSrcTy() == Cast1->getSrcTy()) { 1900 Op0 = Cast0->getOperand(0); 1901 Op1 = Cast1->getOperand(0); 1902 } 1903 1904 Value *V = nullptr; 1905 auto *ICmp0 = dyn_cast<ICmpInst>(Op0); 1906 auto *ICmp1 = dyn_cast<ICmpInst>(Op1); 1907 if (ICmp0 && ICmp1) 1908 V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q) 1909 : simplifyOrOfICmps(ICmp0, ICmp1, Q); 1910 1911 auto *FCmp0 = dyn_cast<FCmpInst>(Op0); 1912 auto *FCmp1 = dyn_cast<FCmpInst>(Op1); 1913 if (FCmp0 && FCmp1) 1914 V = simplifyAndOrOfFCmps(Q, FCmp0, FCmp1, IsAnd); 1915 1916 if (!V) 1917 return nullptr; 1918 if (!Cast0) 1919 return V; 1920 1921 // If we looked through casts, we can only handle a constant simplification 1922 // because we are not allowed to create a cast instruction here. 1923 if (auto *C = dyn_cast<Constant>(V)) 1924 return ConstantFoldCastOperand(Cast0->getOpcode(), C, Cast0->getType(), 1925 Q.DL); 1926 1927 return nullptr; 1928 } 1929 1930 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 1931 const SimplifyQuery &Q, 1932 bool AllowRefinement, 1933 SmallVectorImpl<Instruction *> *DropFlags, 1934 unsigned MaxRecurse); 1935 1936 static Value *simplifyAndOrWithICmpEq(unsigned Opcode, Value *Op0, Value *Op1, 1937 const SimplifyQuery &Q, 1938 unsigned MaxRecurse) { 1939 assert((Opcode == Instruction::And || Opcode == Instruction::Or) && 1940 "Must be and/or"); 1941 ICmpInst::Predicate Pred; 1942 Value *A, *B; 1943 if (!match(Op0, m_ICmp(Pred, m_Value(A), m_Value(B))) || 1944 !ICmpInst::isEquality(Pred)) 1945 return nullptr; 1946 1947 auto Simplify = [&](Value *Res) -> Value * { 1948 Constant *Absorber = ConstantExpr::getBinOpAbsorber(Opcode, Res->getType()); 1949 1950 // and (icmp eq a, b), x implies (a==b) inside x. 1951 // or (icmp ne a, b), x implies (a==b) inside x. 1952 // If x simplifies to true/false, we can simplify the and/or. 1953 if (Pred == 1954 (Opcode == Instruction::And ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE)) { 1955 if (Res == Absorber) 1956 return Absorber; 1957 if (Res == ConstantExpr::getBinOpIdentity(Opcode, Res->getType())) 1958 return Op0; 1959 return nullptr; 1960 } 1961 1962 // If we have and (icmp ne a, b), x and for a==b we can simplify x to false, 1963 // then we can drop the icmp, as x will already be false in the case where 1964 // the icmp is false. Similar for or and true. 1965 if (Res == Absorber) 1966 return Op1; 1967 return nullptr; 1968 }; 1969 1970 // In the final case (Res == Absorber with inverted predicate), it is safe to 1971 // refine poison during simplification, but not undef. For simplicity always 1972 // disable undef-based folds here. 1973 if (Value *Res = simplifyWithOpReplaced(Op1, A, B, Q.getWithoutUndef(), 1974 /* AllowRefinement */ true, 1975 /* DropFlags */ nullptr, MaxRecurse)) 1976 return Simplify(Res); 1977 if (Value *Res = simplifyWithOpReplaced(Op1, B, A, Q.getWithoutUndef(), 1978 /* AllowRefinement */ true, 1979 /* DropFlags */ nullptr, MaxRecurse)) 1980 return Simplify(Res); 1981 1982 return nullptr; 1983 } 1984 1985 /// Given a bitwise logic op, check if the operands are add/sub with a common 1986 /// source value and inverted constant (identity: C - X -> ~(X + ~C)). 1987 static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1, 1988 Instruction::BinaryOps Opcode) { 1989 assert(Op0->getType() == Op1->getType() && "Mismatched binop types"); 1990 assert(BinaryOperator::isBitwiseLogicOp(Opcode) && "Expected logic op"); 1991 Value *X; 1992 Constant *C1, *C2; 1993 if ((match(Op0, m_Add(m_Value(X), m_Constant(C1))) && 1994 match(Op1, m_Sub(m_Constant(C2), m_Specific(X)))) || 1995 (match(Op1, m_Add(m_Value(X), m_Constant(C1))) && 1996 match(Op0, m_Sub(m_Constant(C2), m_Specific(X))))) { 1997 if (ConstantExpr::getNot(C1) == C2) { 1998 // (X + C) & (~C - X) --> (X + C) & ~(X + C) --> 0 1999 // (X + C) | (~C - X) --> (X + C) | ~(X + C) --> -1 2000 // (X + C) ^ (~C - X) --> (X + C) ^ ~(X + C) --> -1 2001 Type *Ty = Op0->getType(); 2002 return Opcode == Instruction::And ? ConstantInt::getNullValue(Ty) 2003 : ConstantInt::getAllOnesValue(Ty); 2004 } 2005 } 2006 return nullptr; 2007 } 2008 2009 // Commutative patterns for and that will be tried with both operand orders. 2010 static Value *simplifyAndCommutative(Value *Op0, Value *Op1, 2011 const SimplifyQuery &Q, 2012 unsigned MaxRecurse) { 2013 // ~A & A = 0 2014 if (match(Op0, m_Not(m_Specific(Op1)))) 2015 return Constant::getNullValue(Op0->getType()); 2016 2017 // (A | ?) & A = A 2018 if (match(Op0, m_c_Or(m_Specific(Op1), m_Value()))) 2019 return Op1; 2020 2021 // (X | ~Y) & (X | Y) --> X 2022 Value *X, *Y; 2023 if (match(Op0, m_c_Or(m_Value(X), m_Not(m_Value(Y)))) && 2024 match(Op1, m_c_Or(m_Specific(X), m_Specific(Y)))) 2025 return X; 2026 2027 // If we have a multiplication overflow check that is being 'and'ed with a 2028 // check that one of the multipliers is not zero, we can omit the 'and', and 2029 // only keep the overflow check. 2030 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, true)) 2031 return Op1; 2032 2033 // -A & A = A if A is a power of two or zero. 2034 if (match(Op0, m_Neg(m_Specific(Op1))) && 2035 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2036 return Op1; 2037 2038 // This is a similar pattern used for checking if a value is a power-of-2: 2039 // (A - 1) & A --> 0 (if A is a power-of-2 or 0) 2040 if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) && 2041 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2042 return Constant::getNullValue(Op1->getType()); 2043 2044 // (x << N) & ((x << M) - 1) --> 0, where x is known to be a power of 2 and 2045 // M <= N. 2046 const APInt *Shift1, *Shift2; 2047 if (match(Op0, m_Shl(m_Value(X), m_APInt(Shift1))) && 2048 match(Op1, m_Add(m_Shl(m_Specific(X), m_APInt(Shift2)), m_AllOnes())) && 2049 isKnownToBeAPowerOfTwo(X, Q.DL, /*OrZero*/ true, /*Depth*/ 0, Q.AC, 2050 Q.CxtI) && 2051 Shift1->uge(*Shift2)) 2052 return Constant::getNullValue(Op0->getType()); 2053 2054 if (Value *V = 2055 simplifyAndOrWithICmpEq(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2056 return V; 2057 2058 return nullptr; 2059 } 2060 2061 /// Given operands for an And, see if we can fold the result. 2062 /// If not, this returns null. 2063 static Value *simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2064 unsigned MaxRecurse) { 2065 if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q)) 2066 return C; 2067 2068 // X & poison -> poison 2069 if (isa<PoisonValue>(Op1)) 2070 return Op1; 2071 2072 // X & undef -> 0 2073 if (Q.isUndefValue(Op1)) 2074 return Constant::getNullValue(Op0->getType()); 2075 2076 // X & X = X 2077 if (Op0 == Op1) 2078 return Op0; 2079 2080 // X & 0 = 0 2081 if (match(Op1, m_Zero())) 2082 return Constant::getNullValue(Op0->getType()); 2083 2084 // X & -1 = X 2085 if (match(Op1, m_AllOnes())) 2086 return Op0; 2087 2088 if (Value *Res = simplifyAndCommutative(Op0, Op1, Q, MaxRecurse)) 2089 return Res; 2090 if (Value *Res = simplifyAndCommutative(Op1, Op0, Q, MaxRecurse)) 2091 return Res; 2092 2093 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And)) 2094 return V; 2095 2096 // A mask that only clears known zeros of a shifted value is a no-op. 2097 const APInt *Mask; 2098 const APInt *ShAmt; 2099 Value *X, *Y; 2100 if (match(Op1, m_APInt(Mask))) { 2101 // If all bits in the inverted and shifted mask are clear: 2102 // and (shl X, ShAmt), Mask --> shl X, ShAmt 2103 if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) && 2104 (~(*Mask)).lshr(*ShAmt).isZero()) 2105 return Op0; 2106 2107 // If all bits in the inverted and shifted mask are clear: 2108 // and (lshr X, ShAmt), Mask --> lshr X, ShAmt 2109 if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) && 2110 (~(*Mask)).shl(*ShAmt).isZero()) 2111 return Op0; 2112 } 2113 2114 // and 2^x-1, 2^C --> 0 where x <= C. 2115 const APInt *PowerC; 2116 Value *Shift; 2117 if (match(Op1, m_Power2(PowerC)) && 2118 match(Op0, m_Add(m_Value(Shift), m_AllOnes())) && 2119 isKnownToBeAPowerOfTwo(Shift, Q.DL, /*OrZero*/ false, 0, Q.AC, Q.CxtI, 2120 Q.DT)) { 2121 KnownBits Known = computeKnownBits(Shift, /* Depth */ 0, Q); 2122 // Use getActiveBits() to make use of the additional power of two knowledge 2123 if (PowerC->getActiveBits() >= Known.getMaxValue().getActiveBits()) 2124 return ConstantInt::getNullValue(Op1->getType()); 2125 } 2126 2127 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true)) 2128 return V; 2129 2130 // Try some generic simplifications for associative operations. 2131 if (Value *V = 2132 simplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2133 return V; 2134 2135 // And distributes over Or. Try some generic simplifications based on this. 2136 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2137 Instruction::Or, Q, MaxRecurse)) 2138 return V; 2139 2140 // And distributes over Xor. Try some generic simplifications based on this. 2141 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2142 Instruction::Xor, Q, MaxRecurse)) 2143 return V; 2144 2145 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2146 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2147 // A & (A && B) -> A && B 2148 if (match(Op1, m_Select(m_Specific(Op0), m_Value(), m_Zero()))) 2149 return Op1; 2150 else if (match(Op0, m_Select(m_Specific(Op1), m_Value(), m_Zero()))) 2151 return Op0; 2152 } 2153 // If the operation is with the result of a select instruction, check 2154 // whether operating on either branch of the select always yields the same 2155 // value. 2156 if (Value *V = 2157 threadBinOpOverSelect(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2158 return V; 2159 } 2160 2161 // If the operation is with the result of a phi instruction, check whether 2162 // operating on all incoming values of the phi always yields the same value. 2163 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2164 if (Value *V = 2165 threadBinOpOverPHI(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2166 return V; 2167 2168 // Assuming the effective width of Y is not larger than A, i.e. all bits 2169 // from X and Y are disjoint in (X << A) | Y, 2170 // if the mask of this AND op covers all bits of X or Y, while it covers 2171 // no bits from the other, we can bypass this AND op. E.g., 2172 // ((X << A) | Y) & Mask -> Y, 2173 // if Mask = ((1 << effective_width_of(Y)) - 1) 2174 // ((X << A) | Y) & Mask -> X << A, 2175 // if Mask = ((1 << effective_width_of(X)) - 1) << A 2176 // SimplifyDemandedBits in InstCombine can optimize the general case. 2177 // This pattern aims to help other passes for a common case. 2178 Value *XShifted; 2179 if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(Mask)) && 2180 match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)), 2181 m_Value(XShifted)), 2182 m_Value(Y)))) { 2183 const unsigned Width = Op0->getType()->getScalarSizeInBits(); 2184 const unsigned ShftCnt = ShAmt->getLimitedValue(Width); 2185 const KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 2186 const unsigned EffWidthY = YKnown.countMaxActiveBits(); 2187 if (EffWidthY <= ShftCnt) { 2188 const KnownBits XKnown = computeKnownBits(X, /* Depth */ 0, Q); 2189 const unsigned EffWidthX = XKnown.countMaxActiveBits(); 2190 const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY); 2191 const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt; 2192 // If the mask is extracting all bits from X or Y as is, we can skip 2193 // this AND op. 2194 if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask)) 2195 return Y; 2196 if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask)) 2197 return XShifted; 2198 } 2199 } 2200 2201 // ((X | Y) ^ X ) & ((X | Y) ^ Y) --> 0 2202 // ((X | Y) ^ Y ) & ((X | Y) ^ X) --> 0 2203 BinaryOperator *Or; 2204 if (match(Op0, m_c_Xor(m_Value(X), 2205 m_CombineAnd(m_BinOp(Or), 2206 m_c_Or(m_Deferred(X), m_Value(Y))))) && 2207 match(Op1, m_c_Xor(m_Specific(Or), m_Specific(Y)))) 2208 return Constant::getNullValue(Op0->getType()); 2209 2210 const APInt *C1; 2211 Value *A; 2212 // (A ^ C) & (A ^ ~C) -> 0 2213 if (match(Op0, m_Xor(m_Value(A), m_APInt(C1))) && 2214 match(Op1, m_Xor(m_Specific(A), m_SpecificInt(~*C1)))) 2215 return Constant::getNullValue(Op0->getType()); 2216 2217 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2218 if (std::optional<bool> Implied = isImpliedCondition(Op0, Op1, Q.DL)) { 2219 // If Op0 is true implies Op1 is true, then Op0 is a subset of Op1. 2220 if (*Implied == true) 2221 return Op0; 2222 // If Op0 is true implies Op1 is false, then they are not true together. 2223 if (*Implied == false) 2224 return ConstantInt::getFalse(Op0->getType()); 2225 } 2226 if (std::optional<bool> Implied = isImpliedCondition(Op1, Op0, Q.DL)) { 2227 // If Op1 is true implies Op0 is true, then Op1 is a subset of Op0. 2228 if (*Implied) 2229 return Op1; 2230 // If Op1 is true implies Op0 is false, then they are not true together. 2231 if (!*Implied) 2232 return ConstantInt::getFalse(Op1->getType()); 2233 } 2234 } 2235 2236 if (Value *V = simplifyByDomEq(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2237 return V; 2238 2239 return nullptr; 2240 } 2241 2242 Value *llvm::simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2243 return ::simplifyAndInst(Op0, Op1, Q, RecursionLimit); 2244 } 2245 2246 // TODO: Many of these folds could use LogicalAnd/LogicalOr. 2247 static Value *simplifyOrLogic(Value *X, Value *Y) { 2248 assert(X->getType() == Y->getType() && "Expected same type for 'or' ops"); 2249 Type *Ty = X->getType(); 2250 2251 // X | ~X --> -1 2252 if (match(Y, m_Not(m_Specific(X)))) 2253 return ConstantInt::getAllOnesValue(Ty); 2254 2255 // X | ~(X & ?) = -1 2256 if (match(Y, m_Not(m_c_And(m_Specific(X), m_Value())))) 2257 return ConstantInt::getAllOnesValue(Ty); 2258 2259 // X | (X & ?) --> X 2260 if (match(Y, m_c_And(m_Specific(X), m_Value()))) 2261 return X; 2262 2263 Value *A, *B; 2264 2265 // (A ^ B) | (A | B) --> A | B 2266 // (A ^ B) | (B | A) --> B | A 2267 if (match(X, m_Xor(m_Value(A), m_Value(B))) && 2268 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2269 return Y; 2270 2271 // ~(A ^ B) | (A | B) --> -1 2272 // ~(A ^ B) | (B | A) --> -1 2273 if (match(X, m_Not(m_Xor(m_Value(A), m_Value(B)))) && 2274 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2275 return ConstantInt::getAllOnesValue(Ty); 2276 2277 // (A & ~B) | (A ^ B) --> A ^ B 2278 // (~B & A) | (A ^ B) --> A ^ B 2279 // (A & ~B) | (B ^ A) --> B ^ A 2280 // (~B & A) | (B ^ A) --> B ^ A 2281 if (match(X, m_c_And(m_Value(A), m_Not(m_Value(B)))) && 2282 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2283 return Y; 2284 2285 // (~A ^ B) | (A & B) --> ~A ^ B 2286 // (B ^ ~A) | (A & B) --> B ^ ~A 2287 // (~A ^ B) | (B & A) --> ~A ^ B 2288 // (B ^ ~A) | (B & A) --> B ^ ~A 2289 if (match(X, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) && 2290 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2291 return X; 2292 2293 // (~A | B) | (A ^ B) --> -1 2294 // (~A | B) | (B ^ A) --> -1 2295 // (B | ~A) | (A ^ B) --> -1 2296 // (B | ~A) | (B ^ A) --> -1 2297 if (match(X, m_c_Or(m_Not(m_Value(A)), m_Value(B))) && 2298 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2299 return ConstantInt::getAllOnesValue(Ty); 2300 2301 // (~A & B) | ~(A | B) --> ~A 2302 // (~A & B) | ~(B | A) --> ~A 2303 // (B & ~A) | ~(A | B) --> ~A 2304 // (B & ~A) | ~(B | A) --> ~A 2305 Value *NotA; 2306 if (match(X, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))), 2307 m_Value(B))) && 2308 match(Y, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) 2309 return NotA; 2310 // The same is true of Logical And 2311 // TODO: This could share the logic of the version above if there was a 2312 // version of LogicalAnd that allowed more than just i1 types. 2313 if (match(X, m_c_LogicalAnd(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))), 2314 m_Value(B))) && 2315 match(Y, m_Not(m_c_LogicalOr(m_Specific(A), m_Specific(B))))) 2316 return NotA; 2317 2318 // ~(A ^ B) | (A & B) --> ~(A ^ B) 2319 // ~(A ^ B) | (B & A) --> ~(A ^ B) 2320 Value *NotAB; 2321 if (match(X, m_CombineAnd(m_Not(m_Xor(m_Value(A), m_Value(B))), 2322 m_Value(NotAB))) && 2323 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2324 return NotAB; 2325 2326 // ~(A & B) | (A ^ B) --> ~(A & B) 2327 // ~(A & B) | (B ^ A) --> ~(A & B) 2328 if (match(X, m_CombineAnd(m_Not(m_And(m_Value(A), m_Value(B))), 2329 m_Value(NotAB))) && 2330 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2331 return NotAB; 2332 2333 return nullptr; 2334 } 2335 2336 /// Given operands for an Or, see if we can fold the result. 2337 /// If not, this returns null. 2338 static Value *simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2339 unsigned MaxRecurse) { 2340 if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q)) 2341 return C; 2342 2343 // X | poison -> poison 2344 if (isa<PoisonValue>(Op1)) 2345 return Op1; 2346 2347 // X | undef -> -1 2348 // X | -1 = -1 2349 // Do not return Op1 because it may contain undef elements if it's a vector. 2350 if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes())) 2351 return Constant::getAllOnesValue(Op0->getType()); 2352 2353 // X | X = X 2354 // X | 0 = X 2355 if (Op0 == Op1 || match(Op1, m_Zero())) 2356 return Op0; 2357 2358 if (Value *R = simplifyOrLogic(Op0, Op1)) 2359 return R; 2360 if (Value *R = simplifyOrLogic(Op1, Op0)) 2361 return R; 2362 2363 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Or)) 2364 return V; 2365 2366 // Rotated -1 is still -1: 2367 // (-1 << X) | (-1 >> (C - X)) --> -1 2368 // (-1 >> X) | (-1 << (C - X)) --> -1 2369 // ...with C <= bitwidth (and commuted variants). 2370 Value *X, *Y; 2371 if ((match(Op0, m_Shl(m_AllOnes(), m_Value(X))) && 2372 match(Op1, m_LShr(m_AllOnes(), m_Value(Y)))) || 2373 (match(Op1, m_Shl(m_AllOnes(), m_Value(X))) && 2374 match(Op0, m_LShr(m_AllOnes(), m_Value(Y))))) { 2375 const APInt *C; 2376 if ((match(X, m_Sub(m_APInt(C), m_Specific(Y))) || 2377 match(Y, m_Sub(m_APInt(C), m_Specific(X)))) && 2378 C->ule(X->getType()->getScalarSizeInBits())) { 2379 return ConstantInt::getAllOnesValue(X->getType()); 2380 } 2381 } 2382 2383 // A funnel shift (rotate) can be decomposed into simpler shifts. See if we 2384 // are mixing in another shift that is redundant with the funnel shift. 2385 2386 // (fshl X, ?, Y) | (shl X, Y) --> fshl X, ?, Y 2387 // (shl X, Y) | (fshl X, ?, Y) --> fshl X, ?, Y 2388 if (match(Op0, 2389 m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) && 2390 match(Op1, m_Shl(m_Specific(X), m_Specific(Y)))) 2391 return Op0; 2392 if (match(Op1, 2393 m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) && 2394 match(Op0, m_Shl(m_Specific(X), m_Specific(Y)))) 2395 return Op1; 2396 2397 // (fshr ?, X, Y) | (lshr X, Y) --> fshr ?, X, Y 2398 // (lshr X, Y) | (fshr ?, X, Y) --> fshr ?, X, Y 2399 if (match(Op0, 2400 m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) && 2401 match(Op1, m_LShr(m_Specific(X), m_Specific(Y)))) 2402 return Op0; 2403 if (match(Op1, 2404 m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) && 2405 match(Op0, m_LShr(m_Specific(X), m_Specific(Y)))) 2406 return Op1; 2407 2408 if (Value *V = 2409 simplifyAndOrWithICmpEq(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2410 return V; 2411 if (Value *V = 2412 simplifyAndOrWithICmpEq(Instruction::Or, Op1, Op0, Q, MaxRecurse)) 2413 return V; 2414 2415 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false)) 2416 return V; 2417 2418 // If we have a multiplication overflow check that is being 'and'ed with a 2419 // check that one of the multipliers is not zero, we can omit the 'and', and 2420 // only keep the overflow check. 2421 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, false)) 2422 return Op1; 2423 if (isCheckForZeroAndMulWithOverflow(Op1, Op0, false)) 2424 return Op0; 2425 2426 // Try some generic simplifications for associative operations. 2427 if (Value *V = 2428 simplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2429 return V; 2430 2431 // Or distributes over And. Try some generic simplifications based on this. 2432 if (Value *V = expandCommutativeBinOp(Instruction::Or, Op0, Op1, 2433 Instruction::And, Q, MaxRecurse)) 2434 return V; 2435 2436 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2437 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2438 // A | (A || B) -> A || B 2439 if (match(Op1, m_Select(m_Specific(Op0), m_One(), m_Value()))) 2440 return Op1; 2441 else if (match(Op0, m_Select(m_Specific(Op1), m_One(), m_Value()))) 2442 return Op0; 2443 } 2444 // If the operation is with the result of a select instruction, check 2445 // whether operating on either branch of the select always yields the same 2446 // value. 2447 if (Value *V = 2448 threadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2449 return V; 2450 } 2451 2452 // (A & C1)|(B & C2) 2453 Value *A, *B; 2454 const APInt *C1, *C2; 2455 if (match(Op0, m_And(m_Value(A), m_APInt(C1))) && 2456 match(Op1, m_And(m_Value(B), m_APInt(C2)))) { 2457 if (*C1 == ~*C2) { 2458 // (A & C1)|(B & C2) 2459 // If we have: ((V + N) & C1) | (V & C2) 2460 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 2461 // replace with V+N. 2462 Value *N; 2463 if (C2->isMask() && // C2 == 0+1+ 2464 match(A, m_c_Add(m_Specific(B), m_Value(N)))) { 2465 // Add commutes, try both ways. 2466 if (MaskedValueIsZero(N, *C2, Q)) 2467 return A; 2468 } 2469 // Or commutes, try both ways. 2470 if (C1->isMask() && match(B, m_c_Add(m_Specific(A), m_Value(N)))) { 2471 // Add commutes, try both ways. 2472 if (MaskedValueIsZero(N, *C1, Q)) 2473 return B; 2474 } 2475 } 2476 } 2477 2478 // If the operation is with the result of a phi instruction, check whether 2479 // operating on all incoming values of the phi always yields the same value. 2480 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2481 if (Value *V = threadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2482 return V; 2483 2484 // (A ^ C) | (A ^ ~C) -> -1, i.e. all bits set to one. 2485 if (match(Op0, m_Xor(m_Value(A), m_APInt(C1))) && 2486 match(Op1, m_Xor(m_Specific(A), m_SpecificInt(~*C1)))) 2487 return Constant::getAllOnesValue(Op0->getType()); 2488 2489 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2490 if (std::optional<bool> Implied = 2491 isImpliedCondition(Op0, Op1, Q.DL, false)) { 2492 // If Op0 is false implies Op1 is false, then Op1 is a subset of Op0. 2493 if (*Implied == false) 2494 return Op0; 2495 // If Op0 is false implies Op1 is true, then at least one is always true. 2496 if (*Implied == true) 2497 return ConstantInt::getTrue(Op0->getType()); 2498 } 2499 if (std::optional<bool> Implied = 2500 isImpliedCondition(Op1, Op0, Q.DL, false)) { 2501 // If Op1 is false implies Op0 is false, then Op0 is a subset of Op1. 2502 if (*Implied == false) 2503 return Op1; 2504 // If Op1 is false implies Op0 is true, then at least one is always true. 2505 if (*Implied == true) 2506 return ConstantInt::getTrue(Op1->getType()); 2507 } 2508 } 2509 2510 if (Value *V = simplifyByDomEq(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2511 return V; 2512 2513 return nullptr; 2514 } 2515 2516 Value *llvm::simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2517 return ::simplifyOrInst(Op0, Op1, Q, RecursionLimit); 2518 } 2519 2520 /// Given operands for a Xor, see if we can fold the result. 2521 /// If not, this returns null. 2522 static Value *simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2523 unsigned MaxRecurse) { 2524 if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q)) 2525 return C; 2526 2527 // X ^ poison -> poison 2528 if (isa<PoisonValue>(Op1)) 2529 return Op1; 2530 2531 // A ^ undef -> undef 2532 if (Q.isUndefValue(Op1)) 2533 return Op1; 2534 2535 // A ^ 0 = A 2536 if (match(Op1, m_Zero())) 2537 return Op0; 2538 2539 // A ^ A = 0 2540 if (Op0 == Op1) 2541 return Constant::getNullValue(Op0->getType()); 2542 2543 // A ^ ~A = ~A ^ A = -1 2544 if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0)))) 2545 return Constant::getAllOnesValue(Op0->getType()); 2546 2547 auto foldAndOrNot = [](Value *X, Value *Y) -> Value * { 2548 Value *A, *B; 2549 // (~A & B) ^ (A | B) --> A -- There are 8 commuted variants. 2550 if (match(X, m_c_And(m_Not(m_Value(A)), m_Value(B))) && 2551 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2552 return A; 2553 2554 // (~A | B) ^ (A & B) --> ~A -- There are 8 commuted variants. 2555 // The 'not' op must contain a complete -1 operand (no undef elements for 2556 // vector) for the transform to be safe. 2557 Value *NotA; 2558 if (match(X, m_c_Or(m_CombineAnd(m_Not(m_Value(A)), m_Value(NotA)), 2559 m_Value(B))) && 2560 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2561 return NotA; 2562 2563 return nullptr; 2564 }; 2565 if (Value *R = foldAndOrNot(Op0, Op1)) 2566 return R; 2567 if (Value *R = foldAndOrNot(Op1, Op0)) 2568 return R; 2569 2570 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor)) 2571 return V; 2572 2573 // Try some generic simplifications for associative operations. 2574 if (Value *V = 2575 simplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, MaxRecurse)) 2576 return V; 2577 2578 // Threading Xor over selects and phi nodes is pointless, so don't bother. 2579 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 2580 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 2581 // only if B and C are equal. If B and C are equal then (since we assume 2582 // that operands have already been simplified) "select(cond, B, C)" should 2583 // have been simplified to the common value of B and C already. Analysing 2584 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 2585 // for threading over phi nodes. 2586 2587 if (Value *V = simplifyByDomEq(Instruction::Xor, Op0, Op1, Q, MaxRecurse)) 2588 return V; 2589 2590 return nullptr; 2591 } 2592 2593 Value *llvm::simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2594 return ::simplifyXorInst(Op0, Op1, Q, RecursionLimit); 2595 } 2596 2597 static Type *getCompareTy(Value *Op) { 2598 return CmpInst::makeCmpResultType(Op->getType()); 2599 } 2600 2601 /// Rummage around inside V looking for something equivalent to the comparison 2602 /// "LHS Pred RHS". Return such a value if found, otherwise return null. 2603 /// Helper function for analyzing max/min idioms. 2604 static Value *extractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 2605 Value *LHS, Value *RHS) { 2606 SelectInst *SI = dyn_cast<SelectInst>(V); 2607 if (!SI) 2608 return nullptr; 2609 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 2610 if (!Cmp) 2611 return nullptr; 2612 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 2613 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 2614 return Cmp; 2615 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 2616 LHS == CmpRHS && RHS == CmpLHS) 2617 return Cmp; 2618 return nullptr; 2619 } 2620 2621 /// Return true if the underlying object (storage) must be disjoint from 2622 /// storage returned by any noalias return call. 2623 static bool isAllocDisjoint(const Value *V) { 2624 // For allocas, we consider only static ones (dynamic 2625 // allocas might be transformed into calls to malloc not simultaneously 2626 // live with the compared-to allocation). For globals, we exclude symbols 2627 // that might be resolve lazily to symbols in another dynamically-loaded 2628 // library (and, thus, could be malloc'ed by the implementation). 2629 if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) 2630 return AI->isStaticAlloca(); 2631 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) 2632 return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() || 2633 GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) && 2634 !GV->isThreadLocal(); 2635 if (const Argument *A = dyn_cast<Argument>(V)) 2636 return A->hasByValAttr(); 2637 return false; 2638 } 2639 2640 /// Return true if V1 and V2 are each the base of some distict storage region 2641 /// [V, object_size(V)] which do not overlap. Note that zero sized regions 2642 /// *are* possible, and that zero sized regions do not overlap with any other. 2643 static bool haveNonOverlappingStorage(const Value *V1, const Value *V2) { 2644 // Global variables always exist, so they always exist during the lifetime 2645 // of each other and all allocas. Global variables themselves usually have 2646 // non-overlapping storage, but since their addresses are constants, the 2647 // case involving two globals does not reach here and is instead handled in 2648 // constant folding. 2649 // 2650 // Two different allocas usually have different addresses... 2651 // 2652 // However, if there's an @llvm.stackrestore dynamically in between two 2653 // allocas, they may have the same address. It's tempting to reduce the 2654 // scope of the problem by only looking at *static* allocas here. That would 2655 // cover the majority of allocas while significantly reducing the likelihood 2656 // of having an @llvm.stackrestore pop up in the middle. However, it's not 2657 // actually impossible for an @llvm.stackrestore to pop up in the middle of 2658 // an entry block. Also, if we have a block that's not attached to a 2659 // function, we can't tell if it's "static" under the current definition. 2660 // Theoretically, this problem could be fixed by creating a new kind of 2661 // instruction kind specifically for static allocas. Such a new instruction 2662 // could be required to be at the top of the entry block, thus preventing it 2663 // from being subject to a @llvm.stackrestore. Instcombine could even 2664 // convert regular allocas into these special allocas. It'd be nifty. 2665 // However, until then, this problem remains open. 2666 // 2667 // So, we'll assume that two non-empty allocas have different addresses 2668 // for now. 2669 auto isByValArg = [](const Value *V) { 2670 const Argument *A = dyn_cast<Argument>(V); 2671 return A && A->hasByValAttr(); 2672 }; 2673 2674 // Byval args are backed by store which does not overlap with each other, 2675 // allocas, or globals. 2676 if (isByValArg(V1)) 2677 return isa<AllocaInst>(V2) || isa<GlobalVariable>(V2) || isByValArg(V2); 2678 if (isByValArg(V2)) 2679 return isa<AllocaInst>(V1) || isa<GlobalVariable>(V1) || isByValArg(V1); 2680 2681 return isa<AllocaInst>(V1) && 2682 (isa<AllocaInst>(V2) || isa<GlobalVariable>(V2)); 2683 } 2684 2685 // A significant optimization not implemented here is assuming that alloca 2686 // addresses are not equal to incoming argument values. They don't *alias*, 2687 // as we say, but that doesn't mean they aren't equal, so we take a 2688 // conservative approach. 2689 // 2690 // This is inspired in part by C++11 5.10p1: 2691 // "Two pointers of the same type compare equal if and only if they are both 2692 // null, both point to the same function, or both represent the same 2693 // address." 2694 // 2695 // This is pretty permissive. 2696 // 2697 // It's also partly due to C11 6.5.9p6: 2698 // "Two pointers compare equal if and only if both are null pointers, both are 2699 // pointers to the same object (including a pointer to an object and a 2700 // subobject at its beginning) or function, both are pointers to one past the 2701 // last element of the same array object, or one is a pointer to one past the 2702 // end of one array object and the other is a pointer to the start of a 2703 // different array object that happens to immediately follow the first array 2704 // object in the address space.) 2705 // 2706 // C11's version is more restrictive, however there's no reason why an argument 2707 // couldn't be a one-past-the-end value for a stack object in the caller and be 2708 // equal to the beginning of a stack object in the callee. 2709 // 2710 // If the C and C++ standards are ever made sufficiently restrictive in this 2711 // area, it may be possible to update LLVM's semantics accordingly and reinstate 2712 // this optimization. 2713 static Constant *computePointerICmp(CmpInst::Predicate Pred, Value *LHS, 2714 Value *RHS, const SimplifyQuery &Q) { 2715 assert(LHS->getType() == RHS->getType() && "Must have same types"); 2716 const DataLayout &DL = Q.DL; 2717 const TargetLibraryInfo *TLI = Q.TLI; 2718 2719 // We can only fold certain predicates on pointer comparisons. 2720 switch (Pred) { 2721 default: 2722 return nullptr; 2723 2724 // Equality comparisons are easy to fold. 2725 case CmpInst::ICMP_EQ: 2726 case CmpInst::ICMP_NE: 2727 break; 2728 2729 // We can only handle unsigned relational comparisons because 'inbounds' on 2730 // a GEP only protects against unsigned wrapping. 2731 case CmpInst::ICMP_UGT: 2732 case CmpInst::ICMP_UGE: 2733 case CmpInst::ICMP_ULT: 2734 case CmpInst::ICMP_ULE: 2735 // However, we have to switch them to their signed variants to handle 2736 // negative indices from the base pointer. 2737 Pred = ICmpInst::getSignedPredicate(Pred); 2738 break; 2739 } 2740 2741 // Strip off any constant offsets so that we can reason about them. 2742 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets 2743 // here and compare base addresses like AliasAnalysis does, however there are 2744 // numerous hazards. AliasAnalysis and its utilities rely on special rules 2745 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis 2746 // doesn't need to guarantee pointer inequality when it says NoAlias. 2747 2748 // Even if an non-inbounds GEP occurs along the path we can still optimize 2749 // equality comparisons concerning the result. 2750 bool AllowNonInbounds = ICmpInst::isEquality(Pred); 2751 unsigned IndexSize = DL.getIndexTypeSizeInBits(LHS->getType()); 2752 APInt LHSOffset(IndexSize, 0), RHSOffset(IndexSize, 0); 2753 LHS = LHS->stripAndAccumulateConstantOffsets(DL, LHSOffset, AllowNonInbounds); 2754 RHS = RHS->stripAndAccumulateConstantOffsets(DL, RHSOffset, AllowNonInbounds); 2755 2756 // If LHS and RHS are related via constant offsets to the same base 2757 // value, we can replace it with an icmp which just compares the offsets. 2758 if (LHS == RHS) 2759 return ConstantInt::get(getCompareTy(LHS), 2760 ICmpInst::compare(LHSOffset, RHSOffset, Pred)); 2761 2762 // Various optimizations for (in)equality comparisons. 2763 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) { 2764 // Different non-empty allocations that exist at the same time have 2765 // different addresses (if the program can tell). If the offsets are 2766 // within the bounds of their allocations (and not one-past-the-end! 2767 // so we can't use inbounds!), and their allocations aren't the same, 2768 // the pointers are not equal. 2769 if (haveNonOverlappingStorage(LHS, RHS)) { 2770 uint64_t LHSSize, RHSSize; 2771 ObjectSizeOpts Opts; 2772 Opts.EvalMode = ObjectSizeOpts::Mode::Min; 2773 auto *F = [](Value *V) -> Function * { 2774 if (auto *I = dyn_cast<Instruction>(V)) 2775 return I->getFunction(); 2776 if (auto *A = dyn_cast<Argument>(V)) 2777 return A->getParent(); 2778 return nullptr; 2779 }(LHS); 2780 Opts.NullIsUnknownSize = F ? NullPointerIsDefined(F) : true; 2781 if (getObjectSize(LHS, LHSSize, DL, TLI, Opts) && LHSSize != 0 && 2782 getObjectSize(RHS, RHSSize, DL, TLI, Opts) && RHSSize != 0) { 2783 APInt Dist = LHSOffset - RHSOffset; 2784 if (Dist.isNonNegative() ? Dist.ult(LHSSize) : (-Dist).ult(RHSSize)) 2785 return ConstantInt::get(getCompareTy(LHS), 2786 !CmpInst::isTrueWhenEqual(Pred)); 2787 } 2788 } 2789 2790 // If one side of the equality comparison must come from a noalias call 2791 // (meaning a system memory allocation function), and the other side must 2792 // come from a pointer that cannot overlap with dynamically-allocated 2793 // memory within the lifetime of the current function (allocas, byval 2794 // arguments, globals), then determine the comparison result here. 2795 SmallVector<const Value *, 8> LHSUObjs, RHSUObjs; 2796 getUnderlyingObjects(LHS, LHSUObjs); 2797 getUnderlyingObjects(RHS, RHSUObjs); 2798 2799 // Is the set of underlying objects all noalias calls? 2800 auto IsNAC = [](ArrayRef<const Value *> Objects) { 2801 return all_of(Objects, isNoAliasCall); 2802 }; 2803 2804 // Is the set of underlying objects all things which must be disjoint from 2805 // noalias calls. We assume that indexing from such disjoint storage 2806 // into the heap is undefined, and thus offsets can be safely ignored. 2807 auto IsAllocDisjoint = [](ArrayRef<const Value *> Objects) { 2808 return all_of(Objects, ::isAllocDisjoint); 2809 }; 2810 2811 if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) || 2812 (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs))) 2813 return ConstantInt::get(getCompareTy(LHS), 2814 !CmpInst::isTrueWhenEqual(Pred)); 2815 2816 // Fold comparisons for non-escaping pointer even if the allocation call 2817 // cannot be elided. We cannot fold malloc comparison to null. Also, the 2818 // dynamic allocation call could be either of the operands. Note that 2819 // the other operand can not be based on the alloc - if it were, then 2820 // the cmp itself would be a capture. 2821 Value *MI = nullptr; 2822 if (isAllocLikeFn(LHS, TLI) && llvm::isKnownNonZero(RHS, Q)) 2823 MI = LHS; 2824 else if (isAllocLikeFn(RHS, TLI) && llvm::isKnownNonZero(LHS, Q)) 2825 MI = RHS; 2826 if (MI) { 2827 // FIXME: This is incorrect, see PR54002. While we can assume that the 2828 // allocation is at an address that makes the comparison false, this 2829 // requires that *all* comparisons to that address be false, which 2830 // InstSimplify cannot guarantee. 2831 struct CustomCaptureTracker : public CaptureTracker { 2832 bool Captured = false; 2833 void tooManyUses() override { Captured = true; } 2834 bool captured(const Use *U) override { 2835 if (auto *ICmp = dyn_cast<ICmpInst>(U->getUser())) { 2836 // Comparison against value stored in global variable. Given the 2837 // pointer does not escape, its value cannot be guessed and stored 2838 // separately in a global variable. 2839 unsigned OtherIdx = 1 - U->getOperandNo(); 2840 auto *LI = dyn_cast<LoadInst>(ICmp->getOperand(OtherIdx)); 2841 if (LI && isa<GlobalVariable>(LI->getPointerOperand())) 2842 return false; 2843 } 2844 2845 Captured = true; 2846 return true; 2847 } 2848 }; 2849 CustomCaptureTracker Tracker; 2850 PointerMayBeCaptured(MI, &Tracker); 2851 if (!Tracker.Captured) 2852 return ConstantInt::get(getCompareTy(LHS), 2853 CmpInst::isFalseWhenEqual(Pred)); 2854 } 2855 } 2856 2857 // Otherwise, fail. 2858 return nullptr; 2859 } 2860 2861 /// Fold an icmp when its operands have i1 scalar type. 2862 static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS, 2863 Value *RHS, const SimplifyQuery &Q) { 2864 Type *ITy = getCompareTy(LHS); // The return type. 2865 Type *OpTy = LHS->getType(); // The operand type. 2866 if (!OpTy->isIntOrIntVectorTy(1)) 2867 return nullptr; 2868 2869 // A boolean compared to true/false can be reduced in 14 out of the 20 2870 // (10 predicates * 2 constants) possible combinations. The other 2871 // 6 cases require a 'not' of the LHS. 2872 2873 auto ExtractNotLHS = [](Value *V) -> Value * { 2874 Value *X; 2875 if (match(V, m_Not(m_Value(X)))) 2876 return X; 2877 return nullptr; 2878 }; 2879 2880 if (match(RHS, m_Zero())) { 2881 switch (Pred) { 2882 case CmpInst::ICMP_NE: // X != 0 -> X 2883 case CmpInst::ICMP_UGT: // X >u 0 -> X 2884 case CmpInst::ICMP_SLT: // X <s 0 -> X 2885 return LHS; 2886 2887 case CmpInst::ICMP_EQ: // not(X) == 0 -> X != 0 -> X 2888 case CmpInst::ICMP_ULE: // not(X) <=u 0 -> X >u 0 -> X 2889 case CmpInst::ICMP_SGE: // not(X) >=s 0 -> X <s 0 -> X 2890 if (Value *X = ExtractNotLHS(LHS)) 2891 return X; 2892 break; 2893 2894 case CmpInst::ICMP_ULT: // X <u 0 -> false 2895 case CmpInst::ICMP_SGT: // X >s 0 -> false 2896 return getFalse(ITy); 2897 2898 case CmpInst::ICMP_UGE: // X >=u 0 -> true 2899 case CmpInst::ICMP_SLE: // X <=s 0 -> true 2900 return getTrue(ITy); 2901 2902 default: 2903 break; 2904 } 2905 } else if (match(RHS, m_One())) { 2906 switch (Pred) { 2907 case CmpInst::ICMP_EQ: // X == 1 -> X 2908 case CmpInst::ICMP_UGE: // X >=u 1 -> X 2909 case CmpInst::ICMP_SLE: // X <=s -1 -> X 2910 return LHS; 2911 2912 case CmpInst::ICMP_NE: // not(X) != 1 -> X == 1 -> X 2913 case CmpInst::ICMP_ULT: // not(X) <=u 1 -> X >=u 1 -> X 2914 case CmpInst::ICMP_SGT: // not(X) >s 1 -> X <=s -1 -> X 2915 if (Value *X = ExtractNotLHS(LHS)) 2916 return X; 2917 break; 2918 2919 case CmpInst::ICMP_UGT: // X >u 1 -> false 2920 case CmpInst::ICMP_SLT: // X <s -1 -> false 2921 return getFalse(ITy); 2922 2923 case CmpInst::ICMP_ULE: // X <=u 1 -> true 2924 case CmpInst::ICMP_SGE: // X >=s -1 -> true 2925 return getTrue(ITy); 2926 2927 default: 2928 break; 2929 } 2930 } 2931 2932 switch (Pred) { 2933 default: 2934 break; 2935 case ICmpInst::ICMP_UGE: 2936 if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false)) 2937 return getTrue(ITy); 2938 break; 2939 case ICmpInst::ICMP_SGE: 2940 /// For signed comparison, the values for an i1 are 0 and -1 2941 /// respectively. This maps into a truth table of: 2942 /// LHS | RHS | LHS >=s RHS | LHS implies RHS 2943 /// 0 | 0 | 1 (0 >= 0) | 1 2944 /// 0 | 1 | 1 (0 >= -1) | 1 2945 /// 1 | 0 | 0 (-1 >= 0) | 0 2946 /// 1 | 1 | 1 (-1 >= -1) | 1 2947 if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false)) 2948 return getTrue(ITy); 2949 break; 2950 case ICmpInst::ICMP_ULE: 2951 if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false)) 2952 return getTrue(ITy); 2953 break; 2954 case ICmpInst::ICMP_SLE: 2955 /// SLE follows the same logic as SGE with the LHS and RHS swapped. 2956 if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false)) 2957 return getTrue(ITy); 2958 break; 2959 } 2960 2961 return nullptr; 2962 } 2963 2964 /// Try hard to fold icmp with zero RHS because this is a common case. 2965 static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS, 2966 Value *RHS, const SimplifyQuery &Q) { 2967 if (!match(RHS, m_Zero())) 2968 return nullptr; 2969 2970 Type *ITy = getCompareTy(LHS); // The return type. 2971 switch (Pred) { 2972 default: 2973 llvm_unreachable("Unknown ICmp predicate!"); 2974 case ICmpInst::ICMP_ULT: 2975 return getFalse(ITy); 2976 case ICmpInst::ICMP_UGE: 2977 return getTrue(ITy); 2978 case ICmpInst::ICMP_EQ: 2979 case ICmpInst::ICMP_ULE: 2980 if (isKnownNonZero(LHS, Q)) 2981 return getFalse(ITy); 2982 break; 2983 case ICmpInst::ICMP_NE: 2984 case ICmpInst::ICMP_UGT: 2985 if (isKnownNonZero(LHS, Q)) 2986 return getTrue(ITy); 2987 break; 2988 case ICmpInst::ICMP_SLT: { 2989 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 2990 if (LHSKnown.isNegative()) 2991 return getTrue(ITy); 2992 if (LHSKnown.isNonNegative()) 2993 return getFalse(ITy); 2994 break; 2995 } 2996 case ICmpInst::ICMP_SLE: { 2997 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 2998 if (LHSKnown.isNegative()) 2999 return getTrue(ITy); 3000 if (LHSKnown.isNonNegative() && isKnownNonZero(LHS, Q)) 3001 return getFalse(ITy); 3002 break; 3003 } 3004 case ICmpInst::ICMP_SGE: { 3005 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 3006 if (LHSKnown.isNegative()) 3007 return getFalse(ITy); 3008 if (LHSKnown.isNonNegative()) 3009 return getTrue(ITy); 3010 break; 3011 } 3012 case ICmpInst::ICMP_SGT: { 3013 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 3014 if (LHSKnown.isNegative()) 3015 return getFalse(ITy); 3016 if (LHSKnown.isNonNegative() && isKnownNonZero(LHS, Q)) 3017 return getTrue(ITy); 3018 break; 3019 } 3020 } 3021 3022 return nullptr; 3023 } 3024 3025 static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS, 3026 Value *RHS, const InstrInfoQuery &IIQ) { 3027 Type *ITy = getCompareTy(RHS); // The return type. 3028 3029 Value *X; 3030 const APInt *C; 3031 if (!match(RHS, m_APIntAllowPoison(C))) 3032 return nullptr; 3033 3034 // Sign-bit checks can be optimized to true/false after unsigned 3035 // floating-point casts: 3036 // icmp slt (bitcast (uitofp X)), 0 --> false 3037 // icmp sgt (bitcast (uitofp X)), -1 --> true 3038 if (match(LHS, m_ElementWiseBitCast(m_UIToFP(m_Value(X))))) { 3039 bool TrueIfSigned; 3040 if (isSignBitCheck(Pred, *C, TrueIfSigned)) 3041 return ConstantInt::getBool(ITy, !TrueIfSigned); 3042 } 3043 3044 // Rule out tautological comparisons (eg., ult 0 or uge 0). 3045 ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C); 3046 if (RHS_CR.isEmptySet()) 3047 return ConstantInt::getFalse(ITy); 3048 if (RHS_CR.isFullSet()) 3049 return ConstantInt::getTrue(ITy); 3050 3051 ConstantRange LHS_CR = 3052 computeConstantRange(LHS, CmpInst::isSigned(Pred), IIQ.UseInstrInfo); 3053 if (!LHS_CR.isFullSet()) { 3054 if (RHS_CR.contains(LHS_CR)) 3055 return ConstantInt::getTrue(ITy); 3056 if (RHS_CR.inverse().contains(LHS_CR)) 3057 return ConstantInt::getFalse(ITy); 3058 } 3059 3060 // (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC) 3061 // (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC) 3062 const APInt *MulC; 3063 if (IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) && 3064 ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowPoison(MulC))) && 3065 *MulC != 0 && C->urem(*MulC) != 0) || 3066 (match(LHS, m_NSWMul(m_Value(), m_APIntAllowPoison(MulC))) && 3067 *MulC != 0 && C->srem(*MulC) != 0))) 3068 return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE); 3069 3070 return nullptr; 3071 } 3072 3073 enum class MonotonicType { GreaterEq, LowerEq }; 3074 3075 /// Get values V_i such that V uge V_i (GreaterEq) or V ule V_i (LowerEq). 3076 static void getUnsignedMonotonicValues(SmallPtrSetImpl<Value *> &Res, Value *V, 3077 MonotonicType Type, unsigned Depth = 0) { 3078 if (!Res.insert(V).second) 3079 return; 3080 3081 // Can be increased if useful. 3082 if (++Depth > 1) 3083 return; 3084 3085 auto *I = dyn_cast<Instruction>(V); 3086 if (!I) 3087 return; 3088 3089 Value *X, *Y; 3090 if (Type == MonotonicType::GreaterEq) { 3091 if (match(I, m_Or(m_Value(X), m_Value(Y))) || 3092 match(I, m_Intrinsic<Intrinsic::uadd_sat>(m_Value(X), m_Value(Y)))) { 3093 getUnsignedMonotonicValues(Res, X, Type, Depth); 3094 getUnsignedMonotonicValues(Res, Y, Type, Depth); 3095 } 3096 } else { 3097 assert(Type == MonotonicType::LowerEq); 3098 switch (I->getOpcode()) { 3099 case Instruction::And: 3100 getUnsignedMonotonicValues(Res, I->getOperand(0), Type, Depth); 3101 getUnsignedMonotonicValues(Res, I->getOperand(1), Type, Depth); 3102 break; 3103 case Instruction::URem: 3104 case Instruction::UDiv: 3105 case Instruction::LShr: 3106 getUnsignedMonotonicValues(Res, I->getOperand(0), Type, Depth); 3107 break; 3108 case Instruction::Call: 3109 if (match(I, m_Intrinsic<Intrinsic::usub_sat>(m_Value(X)))) 3110 getUnsignedMonotonicValues(Res, X, Type, Depth); 3111 break; 3112 default: 3113 break; 3114 } 3115 } 3116 } 3117 3118 static Value *simplifyICmpUsingMonotonicValues(ICmpInst::Predicate Pred, 3119 Value *LHS, Value *RHS) { 3120 if (Pred != ICmpInst::ICMP_UGE && Pred != ICmpInst::ICMP_ULT) 3121 return nullptr; 3122 3123 // We have LHS uge GreaterValues and LowerValues uge RHS. If any of the 3124 // GreaterValues and LowerValues are the same, it follows that LHS uge RHS. 3125 SmallPtrSet<Value *, 4> GreaterValues; 3126 SmallPtrSet<Value *, 4> LowerValues; 3127 getUnsignedMonotonicValues(GreaterValues, LHS, MonotonicType::GreaterEq); 3128 getUnsignedMonotonicValues(LowerValues, RHS, MonotonicType::LowerEq); 3129 for (Value *GV : GreaterValues) 3130 if (LowerValues.contains(GV)) 3131 return ConstantInt::getBool(getCompareTy(LHS), 3132 Pred == ICmpInst::ICMP_UGE); 3133 return nullptr; 3134 } 3135 3136 static Value *simplifyICmpWithBinOpOnLHS(CmpInst::Predicate Pred, 3137 BinaryOperator *LBO, Value *RHS, 3138 const SimplifyQuery &Q, 3139 unsigned MaxRecurse) { 3140 Type *ITy = getCompareTy(RHS); // The return type. 3141 3142 Value *Y = nullptr; 3143 // icmp pred (or X, Y), X 3144 if (match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) { 3145 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) { 3146 KnownBits RHSKnown = computeKnownBits(RHS, /* Depth */ 0, Q); 3147 KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 3148 if (RHSKnown.isNonNegative() && YKnown.isNegative()) 3149 return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy); 3150 if (RHSKnown.isNegative() || YKnown.isNonNegative()) 3151 return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy); 3152 } 3153 } 3154 3155 // icmp pred (urem X, Y), Y 3156 if (match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 3157 switch (Pred) { 3158 default: 3159 break; 3160 case ICmpInst::ICMP_SGT: 3161 case ICmpInst::ICMP_SGE: { 3162 KnownBits Known = computeKnownBits(RHS, /* Depth */ 0, Q); 3163 if (!Known.isNonNegative()) 3164 break; 3165 [[fallthrough]]; 3166 } 3167 case ICmpInst::ICMP_EQ: 3168 case ICmpInst::ICMP_UGT: 3169 case ICmpInst::ICMP_UGE: 3170 return getFalse(ITy); 3171 case ICmpInst::ICMP_SLT: 3172 case ICmpInst::ICMP_SLE: { 3173 KnownBits Known = computeKnownBits(RHS, /* Depth */ 0, Q); 3174 if (!Known.isNonNegative()) 3175 break; 3176 [[fallthrough]]; 3177 } 3178 case ICmpInst::ICMP_NE: 3179 case ICmpInst::ICMP_ULT: 3180 case ICmpInst::ICMP_ULE: 3181 return getTrue(ITy); 3182 } 3183 } 3184 3185 // If x is nonzero: 3186 // x >>u C <u x --> true for C != 0. 3187 // x >>u C != x --> true for C != 0. 3188 // x >>u C >=u x --> false for C != 0. 3189 // x >>u C == x --> false for C != 0. 3190 // x udiv C <u x --> true for C != 1. 3191 // x udiv C != x --> true for C != 1. 3192 // x udiv C >=u x --> false for C != 1. 3193 // x udiv C == x --> false for C != 1. 3194 // TODO: allow non-constant shift amount/divisor 3195 const APInt *C; 3196 if ((match(LBO, m_LShr(m_Specific(RHS), m_APInt(C))) && *C != 0) || 3197 (match(LBO, m_UDiv(m_Specific(RHS), m_APInt(C))) && *C != 1)) { 3198 if (isKnownNonZero(RHS, Q)) { 3199 switch (Pred) { 3200 default: 3201 break; 3202 case ICmpInst::ICMP_EQ: 3203 case ICmpInst::ICMP_UGE: 3204 case ICmpInst::ICMP_UGT: 3205 return getFalse(ITy); 3206 case ICmpInst::ICMP_NE: 3207 case ICmpInst::ICMP_ULT: 3208 case ICmpInst::ICMP_ULE: 3209 return getTrue(ITy); 3210 } 3211 } 3212 } 3213 3214 // (x*C1)/C2 <= x for C1 <= C2. 3215 // This holds even if the multiplication overflows: Assume that x != 0 and 3216 // arithmetic is modulo M. For overflow to occur we must have C1 >= M/x and 3217 // thus C2 >= M/x. It follows that (x*C1)/C2 <= (M-1)/C2 <= ((M-1)*x)/M < x. 3218 // 3219 // Additionally, either the multiplication and division might be represented 3220 // as shifts: 3221 // (x*C1)>>C2 <= x for C1 < 2**C2. 3222 // (x<<C1)/C2 <= x for 2**C1 < C2. 3223 const APInt *C1, *C2; 3224 if ((match(LBO, m_UDiv(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3225 C1->ule(*C2)) || 3226 (match(LBO, m_LShr(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3227 C1->ule(APInt(C2->getBitWidth(), 1) << *C2)) || 3228 (match(LBO, m_UDiv(m_Shl(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3229 (APInt(C1->getBitWidth(), 1) << *C1).ule(*C2))) { 3230 if (Pred == ICmpInst::ICMP_UGT) 3231 return getFalse(ITy); 3232 if (Pred == ICmpInst::ICMP_ULE) 3233 return getTrue(ITy); 3234 } 3235 3236 // (sub C, X) == X, C is odd --> false 3237 // (sub C, X) != X, C is odd --> true 3238 if (match(LBO, m_Sub(m_APIntAllowPoison(C), m_Specific(RHS))) && 3239 (*C & 1) == 1 && ICmpInst::isEquality(Pred)) 3240 return (Pred == ICmpInst::ICMP_EQ) ? getFalse(ITy) : getTrue(ITy); 3241 3242 return nullptr; 3243 } 3244 3245 // If only one of the icmp's operands has NSW flags, try to prove that: 3246 // 3247 // icmp slt (x + C1), (x +nsw C2) 3248 // 3249 // is equivalent to: 3250 // 3251 // icmp slt C1, C2 3252 // 3253 // which is true if x + C2 has the NSW flags set and: 3254 // *) C1 < C2 && C1 >= 0, or 3255 // *) C2 < C1 && C1 <= 0. 3256 // 3257 static bool trySimplifyICmpWithAdds(CmpInst::Predicate Pred, Value *LHS, 3258 Value *RHS, const InstrInfoQuery &IIQ) { 3259 // TODO: only support icmp slt for now. 3260 if (Pred != CmpInst::ICMP_SLT || !IIQ.UseInstrInfo) 3261 return false; 3262 3263 // Canonicalize nsw add as RHS. 3264 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 3265 std::swap(LHS, RHS); 3266 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 3267 return false; 3268 3269 Value *X; 3270 const APInt *C1, *C2; 3271 if (!match(LHS, m_Add(m_Value(X), m_APInt(C1))) || 3272 !match(RHS, m_Add(m_Specific(X), m_APInt(C2)))) 3273 return false; 3274 3275 return (C1->slt(*C2) && C1->isNonNegative()) || 3276 (C2->slt(*C1) && C1->isNonPositive()); 3277 } 3278 3279 /// TODO: A large part of this logic is duplicated in InstCombine's 3280 /// foldICmpBinOp(). We should be able to share that and avoid the code 3281 /// duplication. 3282 static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS, 3283 Value *RHS, const SimplifyQuery &Q, 3284 unsigned MaxRecurse) { 3285 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 3286 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 3287 if (MaxRecurse && (LBO || RBO)) { 3288 // Analyze the case when either LHS or RHS is an add instruction. 3289 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr; 3290 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 3291 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 3292 if (LBO && LBO->getOpcode() == Instruction::Add) { 3293 A = LBO->getOperand(0); 3294 B = LBO->getOperand(1); 3295 NoLHSWrapProblem = 3296 ICmpInst::isEquality(Pred) || 3297 (CmpInst::isUnsigned(Pred) && 3298 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) || 3299 (CmpInst::isSigned(Pred) && 3300 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO))); 3301 } 3302 if (RBO && RBO->getOpcode() == Instruction::Add) { 3303 C = RBO->getOperand(0); 3304 D = RBO->getOperand(1); 3305 NoRHSWrapProblem = 3306 ICmpInst::isEquality(Pred) || 3307 (CmpInst::isUnsigned(Pred) && 3308 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) || 3309 (CmpInst::isSigned(Pred) && 3310 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO))); 3311 } 3312 3313 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 3314 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 3315 if (Value *V = simplifyICmpInst(Pred, A == RHS ? B : A, 3316 Constant::getNullValue(RHS->getType()), Q, 3317 MaxRecurse - 1)) 3318 return V; 3319 3320 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 3321 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 3322 if (Value *V = 3323 simplifyICmpInst(Pred, Constant::getNullValue(LHS->getType()), 3324 C == LHS ? D : C, Q, MaxRecurse - 1)) 3325 return V; 3326 3327 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 3328 bool CanSimplify = (NoLHSWrapProblem && NoRHSWrapProblem) || 3329 trySimplifyICmpWithAdds(Pred, LHS, RHS, Q.IIQ); 3330 if (A && C && (A == C || A == D || B == C || B == D) && CanSimplify) { 3331 // Determine Y and Z in the form icmp (X+Y), (X+Z). 3332 Value *Y, *Z; 3333 if (A == C) { 3334 // C + B == C + D -> B == D 3335 Y = B; 3336 Z = D; 3337 } else if (A == D) { 3338 // D + B == C + D -> B == C 3339 Y = B; 3340 Z = C; 3341 } else if (B == C) { 3342 // A + C == C + D -> A == D 3343 Y = A; 3344 Z = D; 3345 } else { 3346 assert(B == D); 3347 // A + D == C + D -> A == C 3348 Y = A; 3349 Z = C; 3350 } 3351 if (Value *V = simplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1)) 3352 return V; 3353 } 3354 } 3355 3356 if (LBO) 3357 if (Value *V = simplifyICmpWithBinOpOnLHS(Pred, LBO, RHS, Q, MaxRecurse)) 3358 return V; 3359 3360 if (RBO) 3361 if (Value *V = simplifyICmpWithBinOpOnLHS( 3362 ICmpInst::getSwappedPredicate(Pred), RBO, LHS, Q, MaxRecurse)) 3363 return V; 3364 3365 // 0 - (zext X) pred C 3366 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) { 3367 const APInt *C; 3368 if (match(RHS, m_APInt(C))) { 3369 if (C->isStrictlyPositive()) { 3370 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_NE) 3371 return ConstantInt::getTrue(getCompareTy(RHS)); 3372 if (Pred == ICmpInst::ICMP_SGE || Pred == ICmpInst::ICMP_EQ) 3373 return ConstantInt::getFalse(getCompareTy(RHS)); 3374 } 3375 if (C->isNonNegative()) { 3376 if (Pred == ICmpInst::ICMP_SLE) 3377 return ConstantInt::getTrue(getCompareTy(RHS)); 3378 if (Pred == ICmpInst::ICMP_SGT) 3379 return ConstantInt::getFalse(getCompareTy(RHS)); 3380 } 3381 } 3382 } 3383 3384 // If C2 is a power-of-2 and C is not: 3385 // (C2 << X) == C --> false 3386 // (C2 << X) != C --> true 3387 const APInt *C; 3388 if (match(LHS, m_Shl(m_Power2(), m_Value())) && 3389 match(RHS, m_APIntAllowPoison(C)) && !C->isPowerOf2()) { 3390 // C2 << X can equal zero in some circumstances. 3391 // This simplification might be unsafe if C is zero. 3392 // 3393 // We know it is safe if: 3394 // - The shift is nsw. We can't shift out the one bit. 3395 // - The shift is nuw. We can't shift out the one bit. 3396 // - C2 is one. 3397 // - C isn't zero. 3398 if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3399 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3400 match(LHS, m_Shl(m_One(), m_Value())) || !C->isZero()) { 3401 if (Pred == ICmpInst::ICMP_EQ) 3402 return ConstantInt::getFalse(getCompareTy(RHS)); 3403 if (Pred == ICmpInst::ICMP_NE) 3404 return ConstantInt::getTrue(getCompareTy(RHS)); 3405 } 3406 } 3407 3408 // If C is a power-of-2: 3409 // (C << X) >u 0x8000 --> false 3410 // (C << X) <=u 0x8000 --> true 3411 if (match(LHS, m_Shl(m_Power2(), m_Value())) && match(RHS, m_SignMask())) { 3412 if (Pred == ICmpInst::ICMP_UGT) 3413 return ConstantInt::getFalse(getCompareTy(RHS)); 3414 if (Pred == ICmpInst::ICMP_ULE) 3415 return ConstantInt::getTrue(getCompareTy(RHS)); 3416 } 3417 3418 if (!MaxRecurse || !LBO || !RBO || LBO->getOpcode() != RBO->getOpcode()) 3419 return nullptr; 3420 3421 if (LBO->getOperand(0) == RBO->getOperand(0)) { 3422 switch (LBO->getOpcode()) { 3423 default: 3424 break; 3425 case Instruction::Shl: { 3426 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3427 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3428 if (!NUW || (ICmpInst::isSigned(Pred) && !NSW) || 3429 !isKnownNonZero(LBO->getOperand(0), Q)) 3430 break; 3431 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(1), 3432 RBO->getOperand(1), Q, MaxRecurse - 1)) 3433 return V; 3434 break; 3435 } 3436 // If C1 & C2 == C1, A = X and/or C1, B = X and/or C2: 3437 // icmp ule A, B -> true 3438 // icmp ugt A, B -> false 3439 // icmp sle A, B -> true (C1 and C2 are the same sign) 3440 // icmp sgt A, B -> false (C1 and C2 are the same sign) 3441 case Instruction::And: 3442 case Instruction::Or: { 3443 const APInt *C1, *C2; 3444 if (ICmpInst::isRelational(Pred) && 3445 match(LBO->getOperand(1), m_APInt(C1)) && 3446 match(RBO->getOperand(1), m_APInt(C2))) { 3447 if (!C1->isSubsetOf(*C2)) { 3448 std::swap(C1, C2); 3449 Pred = ICmpInst::getSwappedPredicate(Pred); 3450 } 3451 if (C1->isSubsetOf(*C2)) { 3452 if (Pred == ICmpInst::ICMP_ULE) 3453 return ConstantInt::getTrue(getCompareTy(LHS)); 3454 if (Pred == ICmpInst::ICMP_UGT) 3455 return ConstantInt::getFalse(getCompareTy(LHS)); 3456 if (C1->isNonNegative() == C2->isNonNegative()) { 3457 if (Pred == ICmpInst::ICMP_SLE) 3458 return ConstantInt::getTrue(getCompareTy(LHS)); 3459 if (Pred == ICmpInst::ICMP_SGT) 3460 return ConstantInt::getFalse(getCompareTy(LHS)); 3461 } 3462 } 3463 } 3464 break; 3465 } 3466 } 3467 } 3468 3469 if (LBO->getOperand(1) == RBO->getOperand(1)) { 3470 switch (LBO->getOpcode()) { 3471 default: 3472 break; 3473 case Instruction::UDiv: 3474 case Instruction::LShr: 3475 if (ICmpInst::isSigned(Pred) || !Q.IIQ.isExact(LBO) || 3476 !Q.IIQ.isExact(RBO)) 3477 break; 3478 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3479 RBO->getOperand(0), Q, MaxRecurse - 1)) 3480 return V; 3481 break; 3482 case Instruction::SDiv: 3483 if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) || 3484 !Q.IIQ.isExact(RBO)) 3485 break; 3486 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3487 RBO->getOperand(0), Q, MaxRecurse - 1)) 3488 return V; 3489 break; 3490 case Instruction::AShr: 3491 if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO)) 3492 break; 3493 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3494 RBO->getOperand(0), Q, MaxRecurse - 1)) 3495 return V; 3496 break; 3497 case Instruction::Shl: { 3498 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3499 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3500 if (!NUW && !NSW) 3501 break; 3502 if (!NSW && ICmpInst::isSigned(Pred)) 3503 break; 3504 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3505 RBO->getOperand(0), Q, MaxRecurse - 1)) 3506 return V; 3507 break; 3508 } 3509 } 3510 } 3511 return nullptr; 3512 } 3513 3514 /// simplify integer comparisons where at least one operand of the compare 3515 /// matches an integer min/max idiom. 3516 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS, 3517 Value *RHS, const SimplifyQuery &Q, 3518 unsigned MaxRecurse) { 3519 Type *ITy = getCompareTy(LHS); // The return type. 3520 Value *A, *B; 3521 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 3522 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 3523 3524 // Signed variants on "max(a,b)>=a -> true". 3525 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3526 if (A != RHS) 3527 std::swap(A, B); // smax(A, B) pred A. 3528 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3529 // We analyze this as smax(A, B) pred A. 3530 P = Pred; 3531 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 3532 (A == LHS || B == LHS)) { 3533 if (A != LHS) 3534 std::swap(A, B); // A pred smax(A, B). 3535 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3536 // We analyze this as smax(A, B) swapped-pred A. 3537 P = CmpInst::getSwappedPredicate(Pred); 3538 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 3539 (A == RHS || B == RHS)) { 3540 if (A != RHS) 3541 std::swap(A, B); // smin(A, B) pred A. 3542 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3543 // We analyze this as smax(-A, -B) swapped-pred -A. 3544 // Note that we do not need to actually form -A or -B thanks to EqP. 3545 P = CmpInst::getSwappedPredicate(Pred); 3546 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 3547 (A == LHS || B == LHS)) { 3548 if (A != LHS) 3549 std::swap(A, B); // A pred smin(A, B). 3550 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3551 // We analyze this as smax(-A, -B) pred -A. 3552 // Note that we do not need to actually form -A or -B thanks to EqP. 3553 P = Pred; 3554 } 3555 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3556 // Cases correspond to "max(A, B) p A". 3557 switch (P) { 3558 default: 3559 break; 3560 case CmpInst::ICMP_EQ: 3561 case CmpInst::ICMP_SLE: 3562 // Equivalent to "A EqP B". This may be the same as the condition tested 3563 // in the max/min; if so, we can just return that. 3564 if (Value *V = extractEquivalentCondition(LHS, EqP, A, B)) 3565 return V; 3566 if (Value *V = extractEquivalentCondition(RHS, EqP, A, B)) 3567 return V; 3568 // Otherwise, see if "A EqP B" simplifies. 3569 if (MaxRecurse) 3570 if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3571 return V; 3572 break; 3573 case CmpInst::ICMP_NE: 3574 case CmpInst::ICMP_SGT: { 3575 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3576 // Equivalent to "A InvEqP B". This may be the same as the condition 3577 // tested in the max/min; if so, we can just return that. 3578 if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B)) 3579 return V; 3580 if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B)) 3581 return V; 3582 // Otherwise, see if "A InvEqP B" simplifies. 3583 if (MaxRecurse) 3584 if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3585 return V; 3586 break; 3587 } 3588 case CmpInst::ICMP_SGE: 3589 // Always true. 3590 return getTrue(ITy); 3591 case CmpInst::ICMP_SLT: 3592 // Always false. 3593 return getFalse(ITy); 3594 } 3595 } 3596 3597 // Unsigned variants on "max(a,b)>=a -> true". 3598 P = CmpInst::BAD_ICMP_PREDICATE; 3599 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3600 if (A != RHS) 3601 std::swap(A, B); // umax(A, B) pred A. 3602 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3603 // We analyze this as umax(A, B) pred A. 3604 P = Pred; 3605 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 3606 (A == LHS || B == LHS)) { 3607 if (A != LHS) 3608 std::swap(A, B); // A pred umax(A, B). 3609 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3610 // We analyze this as umax(A, B) swapped-pred A. 3611 P = CmpInst::getSwappedPredicate(Pred); 3612 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 3613 (A == RHS || B == RHS)) { 3614 if (A != RHS) 3615 std::swap(A, B); // umin(A, B) pred A. 3616 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3617 // We analyze this as umax(-A, -B) swapped-pred -A. 3618 // Note that we do not need to actually form -A or -B thanks to EqP. 3619 P = CmpInst::getSwappedPredicate(Pred); 3620 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 3621 (A == LHS || B == LHS)) { 3622 if (A != LHS) 3623 std::swap(A, B); // A pred umin(A, B). 3624 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3625 // We analyze this as umax(-A, -B) pred -A. 3626 // Note that we do not need to actually form -A or -B thanks to EqP. 3627 P = Pred; 3628 } 3629 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3630 // Cases correspond to "max(A, B) p A". 3631 switch (P) { 3632 default: 3633 break; 3634 case CmpInst::ICMP_EQ: 3635 case CmpInst::ICMP_ULE: 3636 // Equivalent to "A EqP B". This may be the same as the condition tested 3637 // in the max/min; if so, we can just return that. 3638 if (Value *V = extractEquivalentCondition(LHS, EqP, A, B)) 3639 return V; 3640 if (Value *V = extractEquivalentCondition(RHS, EqP, A, B)) 3641 return V; 3642 // Otherwise, see if "A EqP B" simplifies. 3643 if (MaxRecurse) 3644 if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3645 return V; 3646 break; 3647 case CmpInst::ICMP_NE: 3648 case CmpInst::ICMP_UGT: { 3649 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3650 // Equivalent to "A InvEqP B". This may be the same as the condition 3651 // tested in the max/min; if so, we can just return that. 3652 if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B)) 3653 return V; 3654 if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B)) 3655 return V; 3656 // Otherwise, see if "A InvEqP B" simplifies. 3657 if (MaxRecurse) 3658 if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3659 return V; 3660 break; 3661 } 3662 case CmpInst::ICMP_UGE: 3663 return getTrue(ITy); 3664 case CmpInst::ICMP_ULT: 3665 return getFalse(ITy); 3666 } 3667 } 3668 3669 // Comparing 1 each of min/max with a common operand? 3670 // Canonicalize min operand to RHS. 3671 if (match(LHS, m_UMin(m_Value(), m_Value())) || 3672 match(LHS, m_SMin(m_Value(), m_Value()))) { 3673 std::swap(LHS, RHS); 3674 Pred = ICmpInst::getSwappedPredicate(Pred); 3675 } 3676 3677 Value *C, *D; 3678 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 3679 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 3680 (A == C || A == D || B == C || B == D)) { 3681 // smax(A, B) >=s smin(A, D) --> true 3682 if (Pred == CmpInst::ICMP_SGE) 3683 return getTrue(ITy); 3684 // smax(A, B) <s smin(A, D) --> false 3685 if (Pred == CmpInst::ICMP_SLT) 3686 return getFalse(ITy); 3687 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 3688 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 3689 (A == C || A == D || B == C || B == D)) { 3690 // umax(A, B) >=u umin(A, D) --> true 3691 if (Pred == CmpInst::ICMP_UGE) 3692 return getTrue(ITy); 3693 // umax(A, B) <u umin(A, D) --> false 3694 if (Pred == CmpInst::ICMP_ULT) 3695 return getFalse(ITy); 3696 } 3697 3698 return nullptr; 3699 } 3700 3701 static Value *simplifyICmpWithDominatingAssume(CmpInst::Predicate Predicate, 3702 Value *LHS, Value *RHS, 3703 const SimplifyQuery &Q) { 3704 // Gracefully handle instructions that have not been inserted yet. 3705 if (!Q.AC || !Q.CxtI) 3706 return nullptr; 3707 3708 for (Value *AssumeBaseOp : {LHS, RHS}) { 3709 for (auto &AssumeVH : Q.AC->assumptionsFor(AssumeBaseOp)) { 3710 if (!AssumeVH) 3711 continue; 3712 3713 CallInst *Assume = cast<CallInst>(AssumeVH); 3714 if (std::optional<bool> Imp = isImpliedCondition( 3715 Assume->getArgOperand(0), Predicate, LHS, RHS, Q.DL)) 3716 if (isValidAssumeForContext(Assume, Q.CxtI, Q.DT)) 3717 return ConstantInt::get(getCompareTy(LHS), *Imp); 3718 } 3719 } 3720 3721 return nullptr; 3722 } 3723 3724 static Value *simplifyICmpWithIntrinsicOnLHS(CmpInst::Predicate Pred, 3725 Value *LHS, Value *RHS) { 3726 auto *II = dyn_cast<IntrinsicInst>(LHS); 3727 if (!II) 3728 return nullptr; 3729 3730 switch (II->getIntrinsicID()) { 3731 case Intrinsic::uadd_sat: 3732 // uadd.sat(X, Y) uge X + Y 3733 if (match(RHS, m_c_Add(m_Specific(II->getArgOperand(0)), 3734 m_Specific(II->getArgOperand(1))))) { 3735 if (Pred == ICmpInst::ICMP_UGE) 3736 return ConstantInt::getTrue(getCompareTy(II)); 3737 if (Pred == ICmpInst::ICMP_ULT) 3738 return ConstantInt::getFalse(getCompareTy(II)); 3739 } 3740 return nullptr; 3741 case Intrinsic::usub_sat: 3742 // usub.sat(X, Y) ule X - Y 3743 if (match(RHS, m_Sub(m_Specific(II->getArgOperand(0)), 3744 m_Specific(II->getArgOperand(1))))) { 3745 if (Pred == ICmpInst::ICMP_ULE) 3746 return ConstantInt::getTrue(getCompareTy(II)); 3747 if (Pred == ICmpInst::ICMP_UGT) 3748 return ConstantInt::getFalse(getCompareTy(II)); 3749 } 3750 return nullptr; 3751 default: 3752 return nullptr; 3753 } 3754 } 3755 3756 /// Helper method to get range from metadata or attribute. 3757 static std::optional<ConstantRange> getRange(Value *V, 3758 const InstrInfoQuery &IIQ) { 3759 if (Instruction *I = dyn_cast<Instruction>(V)) 3760 if (MDNode *MD = IIQ.getMetadata(I, LLVMContext::MD_range)) 3761 return getConstantRangeFromMetadata(*MD); 3762 3763 if (const Argument *A = dyn_cast<Argument>(V)) 3764 return A->getRange(); 3765 else if (const CallBase *CB = dyn_cast<CallBase>(V)) 3766 return CB->getRange(); 3767 3768 return std::nullopt; 3769 } 3770 3771 /// Given operands for an ICmpInst, see if we can fold the result. 3772 /// If not, this returns null. 3773 static Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3774 const SimplifyQuery &Q, unsigned MaxRecurse) { 3775 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 3776 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 3777 3778 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 3779 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 3780 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); 3781 3782 // If we have a constant, make sure it is on the RHS. 3783 std::swap(LHS, RHS); 3784 Pred = CmpInst::getSwappedPredicate(Pred); 3785 } 3786 assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X"); 3787 3788 Type *ITy = getCompareTy(LHS); // The return type. 3789 3790 // icmp poison, X -> poison 3791 if (isa<PoisonValue>(RHS)) 3792 return PoisonValue::get(ITy); 3793 3794 // For EQ and NE, we can always pick a value for the undef to make the 3795 // predicate pass or fail, so we can return undef. 3796 // Matches behavior in llvm::ConstantFoldCompareInstruction. 3797 if (Q.isUndefValue(RHS) && ICmpInst::isEquality(Pred)) 3798 return UndefValue::get(ITy); 3799 3800 // icmp X, X -> true/false 3801 // icmp X, undef -> true/false because undef could be X. 3802 if (LHS == RHS || Q.isUndefValue(RHS)) 3803 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 3804 3805 if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q)) 3806 return V; 3807 3808 // TODO: Sink/common this with other potentially expensive calls that use 3809 // ValueTracking? See comment below for isKnownNonEqual(). 3810 if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q)) 3811 return V; 3812 3813 if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ)) 3814 return V; 3815 3816 // If both operands have range metadata, use the metadata 3817 // to simplify the comparison. 3818 if (std::optional<ConstantRange> RhsCr = getRange(RHS, Q.IIQ)) 3819 if (std::optional<ConstantRange> LhsCr = getRange(LHS, Q.IIQ)) { 3820 if (LhsCr->icmp(Pred, *RhsCr)) 3821 return ConstantInt::getTrue(ITy); 3822 3823 if (LhsCr->icmp(CmpInst::getInversePredicate(Pred), *RhsCr)) 3824 return ConstantInt::getFalse(ITy); 3825 } 3826 3827 // Compare of cast, for example (zext X) != 0 -> X != 0 3828 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 3829 Instruction *LI = cast<CastInst>(LHS); 3830 Value *SrcOp = LI->getOperand(0); 3831 Type *SrcTy = SrcOp->getType(); 3832 Type *DstTy = LI->getType(); 3833 3834 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 3835 // if the integer type is the same size as the pointer type. 3836 if (MaxRecurse && isa<PtrToIntInst>(LI) && 3837 Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) { 3838 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 3839 // Transfer the cast to the constant. 3840 if (Value *V = simplifyICmpInst(Pred, SrcOp, 3841 ConstantExpr::getIntToPtr(RHSC, SrcTy), 3842 Q, MaxRecurse - 1)) 3843 return V; 3844 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 3845 if (RI->getOperand(0)->getType() == SrcTy) 3846 // Compare without the cast. 3847 if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q, 3848 MaxRecurse - 1)) 3849 return V; 3850 } 3851 } 3852 3853 if (isa<ZExtInst>(LHS)) { 3854 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 3855 // same type. 3856 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3857 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3858 // Compare X and Y. Note that signed predicates become unsigned. 3859 if (Value *V = 3860 simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), SrcOp, 3861 RI->getOperand(0), Q, MaxRecurse - 1)) 3862 return V; 3863 } 3864 // Fold (zext X) ule (sext X), (zext X) sge (sext X) to true. 3865 else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3866 if (SrcOp == RI->getOperand(0)) { 3867 if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE) 3868 return ConstantInt::getTrue(ITy); 3869 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT) 3870 return ConstantInt::getFalse(ITy); 3871 } 3872 } 3873 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 3874 // too. If not, then try to deduce the result of the comparison. 3875 else if (match(RHS, m_ImmConstant())) { 3876 Constant *C = dyn_cast<Constant>(RHS); 3877 assert(C != nullptr); 3878 3879 // Compute the constant that would happen if we truncated to SrcTy then 3880 // reextended to DstTy. 3881 Constant *Trunc = 3882 ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL); 3883 assert(Trunc && "Constant-fold of ImmConstant should not fail"); 3884 Constant *RExt = 3885 ConstantFoldCastOperand(CastInst::ZExt, Trunc, DstTy, Q.DL); 3886 assert(RExt && "Constant-fold of ImmConstant should not fail"); 3887 Constant *AnyEq = 3888 ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL); 3889 assert(AnyEq && "Constant-fold of ImmConstant should not fail"); 3890 3891 // If the re-extended constant didn't change any of the elements then 3892 // this is effectively also a case of comparing two zero-extended 3893 // values. 3894 if (AnyEq->isAllOnesValue() && MaxRecurse) 3895 if (Value *V = simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 3896 SrcOp, Trunc, Q, MaxRecurse - 1)) 3897 return V; 3898 3899 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 3900 // there. Use this to work out the result of the comparison. 3901 if (AnyEq->isNullValue()) { 3902 switch (Pred) { 3903 default: 3904 llvm_unreachable("Unknown ICmp predicate!"); 3905 // LHS <u RHS. 3906 case ICmpInst::ICMP_EQ: 3907 case ICmpInst::ICMP_UGT: 3908 case ICmpInst::ICMP_UGE: 3909 return Constant::getNullValue(ITy); 3910 3911 case ICmpInst::ICMP_NE: 3912 case ICmpInst::ICMP_ULT: 3913 case ICmpInst::ICMP_ULE: 3914 return Constant::getAllOnesValue(ITy); 3915 3916 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 3917 // is non-negative then LHS <s RHS. 3918 case ICmpInst::ICMP_SGT: 3919 case ICmpInst::ICMP_SGE: 3920 return ConstantFoldCompareInstOperands( 3921 ICmpInst::ICMP_SLT, C, Constant::getNullValue(C->getType()), 3922 Q.DL); 3923 case ICmpInst::ICMP_SLT: 3924 case ICmpInst::ICMP_SLE: 3925 return ConstantFoldCompareInstOperands( 3926 ICmpInst::ICMP_SGE, C, Constant::getNullValue(C->getType()), 3927 Q.DL); 3928 } 3929 } 3930 } 3931 } 3932 3933 if (isa<SExtInst>(LHS)) { 3934 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 3935 // same type. 3936 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3937 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3938 // Compare X and Y. Note that the predicate does not change. 3939 if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q, 3940 MaxRecurse - 1)) 3941 return V; 3942 } 3943 // Fold (sext X) uge (zext X), (sext X) sle (zext X) to true. 3944 else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3945 if (SrcOp == RI->getOperand(0)) { 3946 if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE) 3947 return ConstantInt::getTrue(ITy); 3948 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT) 3949 return ConstantInt::getFalse(ITy); 3950 } 3951 } 3952 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 3953 // too. If not, then try to deduce the result of the comparison. 3954 else if (match(RHS, m_ImmConstant())) { 3955 Constant *C = cast<Constant>(RHS); 3956 3957 // Compute the constant that would happen if we truncated to SrcTy then 3958 // reextended to DstTy. 3959 Constant *Trunc = 3960 ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL); 3961 assert(Trunc && "Constant-fold of ImmConstant should not fail"); 3962 Constant *RExt = 3963 ConstantFoldCastOperand(CastInst::SExt, Trunc, DstTy, Q.DL); 3964 assert(RExt && "Constant-fold of ImmConstant should not fail"); 3965 Constant *AnyEq = 3966 ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL); 3967 assert(AnyEq && "Constant-fold of ImmConstant should not fail"); 3968 3969 // If the re-extended constant didn't change then this is effectively 3970 // also a case of comparing two sign-extended values. 3971 if (AnyEq->isAllOnesValue() && MaxRecurse) 3972 if (Value *V = 3973 simplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse - 1)) 3974 return V; 3975 3976 // Otherwise the upper bits of LHS are all equal, while RHS has varying 3977 // bits there. Use this to work out the result of the comparison. 3978 if (AnyEq->isNullValue()) { 3979 switch (Pred) { 3980 default: 3981 llvm_unreachable("Unknown ICmp predicate!"); 3982 case ICmpInst::ICMP_EQ: 3983 return Constant::getNullValue(ITy); 3984 case ICmpInst::ICMP_NE: 3985 return Constant::getAllOnesValue(ITy); 3986 3987 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 3988 // LHS >s RHS. 3989 case ICmpInst::ICMP_SGT: 3990 case ICmpInst::ICMP_SGE: 3991 return ConstantFoldCompareInstOperands( 3992 ICmpInst::ICMP_SLT, C, Constant::getNullValue(C->getType()), 3993 Q.DL); 3994 case ICmpInst::ICMP_SLT: 3995 case ICmpInst::ICMP_SLE: 3996 return ConstantFoldCompareInstOperands( 3997 ICmpInst::ICMP_SGE, C, Constant::getNullValue(C->getType()), 3998 Q.DL); 3999 4000 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 4001 // LHS >u RHS. 4002 case ICmpInst::ICMP_UGT: 4003 case ICmpInst::ICMP_UGE: 4004 // Comparison is true iff the LHS <s 0. 4005 if (MaxRecurse) 4006 if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 4007 Constant::getNullValue(SrcTy), Q, 4008 MaxRecurse - 1)) 4009 return V; 4010 break; 4011 case ICmpInst::ICMP_ULT: 4012 case ICmpInst::ICMP_ULE: 4013 // Comparison is true iff the LHS >=s 0. 4014 if (MaxRecurse) 4015 if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 4016 Constant::getNullValue(SrcTy), Q, 4017 MaxRecurse - 1)) 4018 return V; 4019 break; 4020 } 4021 } 4022 } 4023 } 4024 } 4025 4026 // icmp eq|ne X, Y -> false|true if X != Y 4027 // This is potentially expensive, and we have already computedKnownBits for 4028 // compares with 0 above here, so only try this for a non-zero compare. 4029 if (ICmpInst::isEquality(Pred) && !match(RHS, m_Zero()) && 4030 isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) { 4031 return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy); 4032 } 4033 4034 if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse)) 4035 return V; 4036 4037 if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse)) 4038 return V; 4039 4040 if (Value *V = simplifyICmpWithIntrinsicOnLHS(Pred, LHS, RHS)) 4041 return V; 4042 if (Value *V = simplifyICmpWithIntrinsicOnLHS( 4043 ICmpInst::getSwappedPredicate(Pred), RHS, LHS)) 4044 return V; 4045 4046 if (Value *V = simplifyICmpUsingMonotonicValues(Pred, LHS, RHS)) 4047 return V; 4048 if (Value *V = simplifyICmpUsingMonotonicValues( 4049 ICmpInst::getSwappedPredicate(Pred), RHS, LHS)) 4050 return V; 4051 4052 if (Value *V = simplifyICmpWithDominatingAssume(Pred, LHS, RHS, Q)) 4053 return V; 4054 4055 if (std::optional<bool> Res = 4056 isImpliedByDomCondition(Pred, LHS, RHS, Q.CxtI, Q.DL)) 4057 return ConstantInt::getBool(ITy, *Res); 4058 4059 // Simplify comparisons of related pointers using a powerful, recursive 4060 // GEP-walk when we have target data available.. 4061 if (LHS->getType()->isPointerTy()) 4062 if (auto *C = computePointerICmp(Pred, LHS, RHS, Q)) 4063 return C; 4064 if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS)) 4065 if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS)) 4066 if (CLHS->getPointerOperandType() == CRHS->getPointerOperandType() && 4067 Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) == 4068 Q.DL.getTypeSizeInBits(CLHS->getType())) 4069 if (auto *C = computePointerICmp(Pred, CLHS->getPointerOperand(), 4070 CRHS->getPointerOperand(), Q)) 4071 return C; 4072 4073 // If the comparison is with the result of a select instruction, check whether 4074 // comparing with either branch of the select always yields the same value. 4075 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 4076 if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 4077 return V; 4078 4079 // If the comparison is with the result of a phi instruction, check whether 4080 // doing the compare with each incoming phi value yields a common result. 4081 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 4082 if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 4083 return V; 4084 4085 return nullptr; 4086 } 4087 4088 Value *llvm::simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4089 const SimplifyQuery &Q) { 4090 return ::simplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 4091 } 4092 4093 /// Given operands for an FCmpInst, see if we can fold the result. 4094 /// If not, this returns null. 4095 static Value *simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4096 FastMathFlags FMF, const SimplifyQuery &Q, 4097 unsigned MaxRecurse) { 4098 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 4099 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 4100 4101 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 4102 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 4103 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI, 4104 Q.CxtI); 4105 4106 // If we have a constant, make sure it is on the RHS. 4107 std::swap(LHS, RHS); 4108 Pred = CmpInst::getSwappedPredicate(Pred); 4109 } 4110 4111 // Fold trivial predicates. 4112 Type *RetTy = getCompareTy(LHS); 4113 if (Pred == FCmpInst::FCMP_FALSE) 4114 return getFalse(RetTy); 4115 if (Pred == FCmpInst::FCMP_TRUE) 4116 return getTrue(RetTy); 4117 4118 // fcmp pred x, poison and fcmp pred poison, x 4119 // fold to poison 4120 if (isa<PoisonValue>(LHS) || isa<PoisonValue>(RHS)) 4121 return PoisonValue::get(RetTy); 4122 4123 // fcmp pred x, undef and fcmp pred undef, x 4124 // fold to true if unordered, false if ordered 4125 if (Q.isUndefValue(LHS) || Q.isUndefValue(RHS)) { 4126 // Choosing NaN for the undef will always make unordered comparison succeed 4127 // and ordered comparison fail. 4128 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 4129 } 4130 4131 // fcmp x,x -> true/false. Not all compares are foldable. 4132 if (LHS == RHS) { 4133 if (CmpInst::isTrueWhenEqual(Pred)) 4134 return getTrue(RetTy); 4135 if (CmpInst::isFalseWhenEqual(Pred)) 4136 return getFalse(RetTy); 4137 } 4138 4139 // Fold (un)ordered comparison if we can determine there are no NaNs. 4140 // 4141 // This catches the 2 variable input case, constants are handled below as a 4142 // class-like compare. 4143 if (Pred == FCmpInst::FCMP_ORD || Pred == FCmpInst::FCMP_UNO) { 4144 KnownFPClass RHSClass = 4145 computeKnownFPClass(RHS, fcAllFlags, /*Depth=*/0, Q); 4146 KnownFPClass LHSClass = 4147 computeKnownFPClass(LHS, fcAllFlags, /*Depth=*/0, Q); 4148 4149 if (FMF.noNaNs() || 4150 (RHSClass.isKnownNeverNaN() && LHSClass.isKnownNeverNaN())) 4151 return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD); 4152 4153 if (RHSClass.isKnownAlwaysNaN() || LHSClass.isKnownAlwaysNaN()) 4154 return ConstantInt::get(RetTy, Pred == CmpInst::FCMP_UNO); 4155 } 4156 4157 const APFloat *C = nullptr; 4158 match(RHS, m_APFloatAllowPoison(C)); 4159 std::optional<KnownFPClass> FullKnownClassLHS; 4160 4161 // Lazily compute the possible classes for LHS. Avoid computing it twice if 4162 // RHS is a 0. 4163 auto computeLHSClass = [=, &FullKnownClassLHS](FPClassTest InterestedFlags = 4164 fcAllFlags) { 4165 if (FullKnownClassLHS) 4166 return *FullKnownClassLHS; 4167 return computeKnownFPClass(LHS, FMF, InterestedFlags, 0, Q); 4168 }; 4169 4170 if (C && Q.CxtI) { 4171 // Fold out compares that express a class test. 4172 // 4173 // FIXME: Should be able to perform folds without context 4174 // instruction. Always pass in the context function? 4175 4176 const Function *ParentF = Q.CxtI->getFunction(); 4177 auto [ClassVal, ClassTest] = fcmpToClassTest(Pred, *ParentF, LHS, C); 4178 if (ClassVal) { 4179 FullKnownClassLHS = computeLHSClass(); 4180 if ((FullKnownClassLHS->KnownFPClasses & ClassTest) == fcNone) 4181 return getFalse(RetTy); 4182 if ((FullKnownClassLHS->KnownFPClasses & ~ClassTest) == fcNone) 4183 return getTrue(RetTy); 4184 } 4185 } 4186 4187 // Handle fcmp with constant RHS. 4188 if (C) { 4189 // TODO: If we always required a context function, we wouldn't need to 4190 // special case nans. 4191 if (C->isNaN()) 4192 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 4193 4194 // TODO: Need version fcmpToClassTest which returns implied class when the 4195 // compare isn't a complete class test. e.g. > 1.0 implies fcPositive, but 4196 // isn't implementable as a class call. 4197 if (C->isNegative() && !C->isNegZero()) { 4198 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4199 4200 // TODO: We can catch more cases by using a range check rather than 4201 // relying on CannotBeOrderedLessThanZero. 4202 switch (Pred) { 4203 case FCmpInst::FCMP_UGE: 4204 case FCmpInst::FCMP_UGT: 4205 case FCmpInst::FCMP_UNE: { 4206 KnownFPClass KnownClass = computeLHSClass(Interested); 4207 4208 // (X >= 0) implies (X > C) when (C < 0) 4209 if (KnownClass.cannotBeOrderedLessThanZero()) 4210 return getTrue(RetTy); 4211 break; 4212 } 4213 case FCmpInst::FCMP_OEQ: 4214 case FCmpInst::FCMP_OLE: 4215 case FCmpInst::FCMP_OLT: { 4216 KnownFPClass KnownClass = computeLHSClass(Interested); 4217 4218 // (X >= 0) implies !(X < C) when (C < 0) 4219 if (KnownClass.cannotBeOrderedLessThanZero()) 4220 return getFalse(RetTy); 4221 break; 4222 } 4223 default: 4224 break; 4225 } 4226 } 4227 // Check comparison of [minnum/maxnum with constant] with other constant. 4228 const APFloat *C2; 4229 if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) && 4230 *C2 < *C) || 4231 (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) && 4232 *C2 > *C)) { 4233 bool IsMaxNum = 4234 cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum; 4235 // The ordered relationship and minnum/maxnum guarantee that we do not 4236 // have NaN constants, so ordered/unordered preds are handled the same. 4237 switch (Pred) { 4238 case FCmpInst::FCMP_OEQ: 4239 case FCmpInst::FCMP_UEQ: 4240 // minnum(X, LesserC) == C --> false 4241 // maxnum(X, GreaterC) == C --> false 4242 return getFalse(RetTy); 4243 case FCmpInst::FCMP_ONE: 4244 case FCmpInst::FCMP_UNE: 4245 // minnum(X, LesserC) != C --> true 4246 // maxnum(X, GreaterC) != C --> true 4247 return getTrue(RetTy); 4248 case FCmpInst::FCMP_OGE: 4249 case FCmpInst::FCMP_UGE: 4250 case FCmpInst::FCMP_OGT: 4251 case FCmpInst::FCMP_UGT: 4252 // minnum(X, LesserC) >= C --> false 4253 // minnum(X, LesserC) > C --> false 4254 // maxnum(X, GreaterC) >= C --> true 4255 // maxnum(X, GreaterC) > C --> true 4256 return ConstantInt::get(RetTy, IsMaxNum); 4257 case FCmpInst::FCMP_OLE: 4258 case FCmpInst::FCMP_ULE: 4259 case FCmpInst::FCMP_OLT: 4260 case FCmpInst::FCMP_ULT: 4261 // minnum(X, LesserC) <= C --> true 4262 // minnum(X, LesserC) < C --> true 4263 // maxnum(X, GreaterC) <= C --> false 4264 // maxnum(X, GreaterC) < C --> false 4265 return ConstantInt::get(RetTy, !IsMaxNum); 4266 default: 4267 // TRUE/FALSE/ORD/UNO should be handled before this. 4268 llvm_unreachable("Unexpected fcmp predicate"); 4269 } 4270 } 4271 } 4272 4273 // TODO: Could fold this with above if there were a matcher which returned all 4274 // classes in a non-splat vector. 4275 if (match(RHS, m_AnyZeroFP())) { 4276 switch (Pred) { 4277 case FCmpInst::FCMP_OGE: 4278 case FCmpInst::FCMP_ULT: { 4279 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4280 if (!FMF.noNaNs()) 4281 Interested |= fcNan; 4282 4283 KnownFPClass Known = computeLHSClass(Interested); 4284 4285 // Positive or zero X >= 0.0 --> true 4286 // Positive or zero X < 0.0 --> false 4287 if ((FMF.noNaNs() || Known.isKnownNeverNaN()) && 4288 Known.cannotBeOrderedLessThanZero()) 4289 return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy); 4290 break; 4291 } 4292 case FCmpInst::FCMP_UGE: 4293 case FCmpInst::FCMP_OLT: { 4294 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4295 KnownFPClass Known = computeLHSClass(Interested); 4296 4297 // Positive or zero or nan X >= 0.0 --> true 4298 // Positive or zero or nan X < 0.0 --> false 4299 if (Known.cannotBeOrderedLessThanZero()) 4300 return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy); 4301 break; 4302 } 4303 default: 4304 break; 4305 } 4306 } 4307 4308 // If the comparison is with the result of a select instruction, check whether 4309 // comparing with either branch of the select always yields the same value. 4310 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 4311 if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 4312 return V; 4313 4314 // If the comparison is with the result of a phi instruction, check whether 4315 // doing the compare with each incoming phi value yields a common result. 4316 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 4317 if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 4318 return V; 4319 4320 return nullptr; 4321 } 4322 4323 Value *llvm::simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4324 FastMathFlags FMF, const SimplifyQuery &Q) { 4325 return ::simplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit); 4326 } 4327 4328 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 4329 const SimplifyQuery &Q, 4330 bool AllowRefinement, 4331 SmallVectorImpl<Instruction *> *DropFlags, 4332 unsigned MaxRecurse) { 4333 assert((AllowRefinement || !Q.CanUseUndef) && 4334 "If AllowRefinement=false then CanUseUndef=false"); 4335 4336 // Trivial replacement. 4337 if (V == Op) 4338 return RepOp; 4339 4340 if (!MaxRecurse--) 4341 return nullptr; 4342 4343 // We cannot replace a constant, and shouldn't even try. 4344 if (isa<Constant>(Op)) 4345 return nullptr; 4346 4347 auto *I = dyn_cast<Instruction>(V); 4348 if (!I) 4349 return nullptr; 4350 4351 // The arguments of a phi node might refer to a value from a previous 4352 // cycle iteration. 4353 if (isa<PHINode>(I)) 4354 return nullptr; 4355 4356 // For vector types, the simplification must hold per-lane, so forbid 4357 // potentially cross-lane operations like shufflevector. 4358 if (Op->getType()->isVectorTy() && !isNotCrossLaneOperation(I)) 4359 return nullptr; 4360 4361 // Don't fold away llvm.is.constant checks based on assumptions. 4362 if (match(I, m_Intrinsic<Intrinsic::is_constant>())) 4363 return nullptr; 4364 4365 // Don't simplify freeze. 4366 if (isa<FreezeInst>(I)) 4367 return nullptr; 4368 4369 // Replace Op with RepOp in instruction operands. 4370 SmallVector<Value *, 8> NewOps; 4371 bool AnyReplaced = false; 4372 for (Value *InstOp : I->operands()) { 4373 if (Value *NewInstOp = simplifyWithOpReplaced( 4374 InstOp, Op, RepOp, Q, AllowRefinement, DropFlags, MaxRecurse)) { 4375 NewOps.push_back(NewInstOp); 4376 AnyReplaced = InstOp != NewInstOp; 4377 } else { 4378 NewOps.push_back(InstOp); 4379 } 4380 4381 // Bail out if any operand is undef and SimplifyQuery disables undef 4382 // simplification. Constant folding currently doesn't respect this option. 4383 if (isa<UndefValue>(NewOps.back()) && !Q.CanUseUndef) 4384 return nullptr; 4385 } 4386 4387 if (!AnyReplaced) 4388 return nullptr; 4389 4390 if (!AllowRefinement) { 4391 // General InstSimplify functions may refine the result, e.g. by returning 4392 // a constant for a potentially poison value. To avoid this, implement only 4393 // a few non-refining but profitable transforms here. 4394 4395 if (auto *BO = dyn_cast<BinaryOperator>(I)) { 4396 unsigned Opcode = BO->getOpcode(); 4397 // id op x -> x, x op id -> x 4398 if (NewOps[0] == ConstantExpr::getBinOpIdentity(Opcode, I->getType())) 4399 return NewOps[1]; 4400 if (NewOps[1] == ConstantExpr::getBinOpIdentity(Opcode, I->getType(), 4401 /* RHS */ true)) 4402 return NewOps[0]; 4403 4404 // x & x -> x, x | x -> x 4405 if ((Opcode == Instruction::And || Opcode == Instruction::Or) && 4406 NewOps[0] == NewOps[1]) { 4407 // or disjoint x, x results in poison. 4408 if (auto *PDI = dyn_cast<PossiblyDisjointInst>(BO)) { 4409 if (PDI->isDisjoint()) { 4410 if (!DropFlags) 4411 return nullptr; 4412 DropFlags->push_back(BO); 4413 } 4414 } 4415 return NewOps[0]; 4416 } 4417 4418 // x - x -> 0, x ^ x -> 0. This is non-refining, because x is non-poison 4419 // by assumption and this case never wraps, so nowrap flags can be 4420 // ignored. 4421 if ((Opcode == Instruction::Sub || Opcode == Instruction::Xor) && 4422 NewOps[0] == RepOp && NewOps[1] == RepOp) 4423 return Constant::getNullValue(I->getType()); 4424 4425 // If we are substituting an absorber constant into a binop and extra 4426 // poison can't leak if we remove the select -- because both operands of 4427 // the binop are based on the same value -- then it may be safe to replace 4428 // the value with the absorber constant. Examples: 4429 // (Op == 0) ? 0 : (Op & -Op) --> Op & -Op 4430 // (Op == 0) ? 0 : (Op * (binop Op, C)) --> Op * (binop Op, C) 4431 // (Op == -1) ? -1 : (Op | (binop C, Op) --> Op | (binop C, Op) 4432 Constant *Absorber = 4433 ConstantExpr::getBinOpAbsorber(Opcode, I->getType()); 4434 if ((NewOps[0] == Absorber || NewOps[1] == Absorber) && 4435 impliesPoison(BO, Op)) 4436 return Absorber; 4437 } 4438 4439 if (isa<GetElementPtrInst>(I)) { 4440 // getelementptr x, 0 -> x. 4441 // This never returns poison, even if inbounds is set. 4442 if (NewOps.size() == 2 && match(NewOps[1], m_Zero())) 4443 return NewOps[0]; 4444 } 4445 } else { 4446 // The simplification queries below may return the original value. Consider: 4447 // %div = udiv i32 %arg, %arg2 4448 // %mul = mul nsw i32 %div, %arg2 4449 // %cmp = icmp eq i32 %mul, %arg 4450 // %sel = select i1 %cmp, i32 %div, i32 undef 4451 // Replacing %arg by %mul, %div becomes "udiv i32 %mul, %arg2", which 4452 // simplifies back to %arg. This can only happen because %mul does not 4453 // dominate %div. To ensure a consistent return value contract, we make sure 4454 // that this case returns nullptr as well. 4455 auto PreventSelfSimplify = [V](Value *Simplified) { 4456 return Simplified != V ? Simplified : nullptr; 4457 }; 4458 4459 return PreventSelfSimplify( 4460 ::simplifyInstructionWithOperands(I, NewOps, Q, MaxRecurse)); 4461 } 4462 4463 // If all operands are constant after substituting Op for RepOp then we can 4464 // constant fold the instruction. 4465 SmallVector<Constant *, 8> ConstOps; 4466 for (Value *NewOp : NewOps) { 4467 if (Constant *ConstOp = dyn_cast<Constant>(NewOp)) 4468 ConstOps.push_back(ConstOp); 4469 else 4470 return nullptr; 4471 } 4472 4473 // Consider: 4474 // %cmp = icmp eq i32 %x, 2147483647 4475 // %add = add nsw i32 %x, 1 4476 // %sel = select i1 %cmp, i32 -2147483648, i32 %add 4477 // 4478 // We can't replace %sel with %add unless we strip away the flags (which 4479 // will be done in InstCombine). 4480 // TODO: This may be unsound, because it only catches some forms of 4481 // refinement. 4482 if (!AllowRefinement) { 4483 if (canCreatePoison(cast<Operator>(I), !DropFlags)) { 4484 // abs cannot create poison if the value is known to never be int_min. 4485 if (auto *II = dyn_cast<IntrinsicInst>(I); 4486 II && II->getIntrinsicID() == Intrinsic::abs) { 4487 if (!ConstOps[0]->isNotMinSignedValue()) 4488 return nullptr; 4489 } else 4490 return nullptr; 4491 } 4492 Constant *Res = ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI, 4493 /*AllowNonDeterministic=*/false); 4494 if (DropFlags && Res && I->hasPoisonGeneratingAnnotations()) 4495 DropFlags->push_back(I); 4496 return Res; 4497 } 4498 4499 return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI, 4500 /*AllowNonDeterministic=*/false); 4501 } 4502 4503 Value *llvm::simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 4504 const SimplifyQuery &Q, 4505 bool AllowRefinement, 4506 SmallVectorImpl<Instruction *> *DropFlags) { 4507 // If refinement is disabled, also disable undef simplifications (which are 4508 // always refinements) in SimplifyQuery. 4509 if (!AllowRefinement) 4510 return ::simplifyWithOpReplaced(V, Op, RepOp, Q.getWithoutUndef(), 4511 AllowRefinement, DropFlags, RecursionLimit); 4512 return ::simplifyWithOpReplaced(V, Op, RepOp, Q, AllowRefinement, DropFlags, 4513 RecursionLimit); 4514 } 4515 4516 /// Try to simplify a select instruction when its condition operand is an 4517 /// integer comparison where one operand of the compare is a constant. 4518 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X, 4519 const APInt *Y, bool TrueWhenUnset) { 4520 const APInt *C; 4521 4522 // (X & Y) == 0 ? X & ~Y : X --> X 4523 // (X & Y) != 0 ? X & ~Y : X --> X & ~Y 4524 if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) && 4525 *Y == ~*C) 4526 return TrueWhenUnset ? FalseVal : TrueVal; 4527 4528 // (X & Y) == 0 ? X : X & ~Y --> X & ~Y 4529 // (X & Y) != 0 ? X : X & ~Y --> X 4530 if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) && 4531 *Y == ~*C) 4532 return TrueWhenUnset ? FalseVal : TrueVal; 4533 4534 if (Y->isPowerOf2()) { 4535 // (X & Y) == 0 ? X | Y : X --> X | Y 4536 // (X & Y) != 0 ? X | Y : X --> X 4537 if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) && 4538 *Y == *C) { 4539 // We can't return the or if it has the disjoint flag. 4540 if (TrueWhenUnset && cast<PossiblyDisjointInst>(TrueVal)->isDisjoint()) 4541 return nullptr; 4542 return TrueWhenUnset ? TrueVal : FalseVal; 4543 } 4544 4545 // (X & Y) == 0 ? X : X | Y --> X 4546 // (X & Y) != 0 ? X : X | Y --> X | Y 4547 if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) && 4548 *Y == *C) { 4549 // We can't return the or if it has the disjoint flag. 4550 if (!TrueWhenUnset && cast<PossiblyDisjointInst>(FalseVal)->isDisjoint()) 4551 return nullptr; 4552 return TrueWhenUnset ? TrueVal : FalseVal; 4553 } 4554 } 4555 4556 return nullptr; 4557 } 4558 4559 static Value *simplifyCmpSelOfMaxMin(Value *CmpLHS, Value *CmpRHS, 4560 ICmpInst::Predicate Pred, Value *TVal, 4561 Value *FVal) { 4562 // Canonicalize common cmp+sel operand as CmpLHS. 4563 if (CmpRHS == TVal || CmpRHS == FVal) { 4564 std::swap(CmpLHS, CmpRHS); 4565 Pred = ICmpInst::getSwappedPredicate(Pred); 4566 } 4567 4568 // Canonicalize common cmp+sel operand as TVal. 4569 if (CmpLHS == FVal) { 4570 std::swap(TVal, FVal); 4571 Pred = ICmpInst::getInversePredicate(Pred); 4572 } 4573 4574 // A vector select may be shuffling together elements that are equivalent 4575 // based on the max/min/select relationship. 4576 Value *X = CmpLHS, *Y = CmpRHS; 4577 bool PeekedThroughSelectShuffle = false; 4578 auto *Shuf = dyn_cast<ShuffleVectorInst>(FVal); 4579 if (Shuf && Shuf->isSelect()) { 4580 if (Shuf->getOperand(0) == Y) 4581 FVal = Shuf->getOperand(1); 4582 else if (Shuf->getOperand(1) == Y) 4583 FVal = Shuf->getOperand(0); 4584 else 4585 return nullptr; 4586 PeekedThroughSelectShuffle = true; 4587 } 4588 4589 // (X pred Y) ? X : max/min(X, Y) 4590 auto *MMI = dyn_cast<MinMaxIntrinsic>(FVal); 4591 if (!MMI || TVal != X || 4592 !match(FVal, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) 4593 return nullptr; 4594 4595 // (X > Y) ? X : max(X, Y) --> max(X, Y) 4596 // (X >= Y) ? X : max(X, Y) --> max(X, Y) 4597 // (X < Y) ? X : min(X, Y) --> min(X, Y) 4598 // (X <= Y) ? X : min(X, Y) --> min(X, Y) 4599 // 4600 // The equivalence allows a vector select (shuffle) of max/min and Y. Ex: 4601 // (X > Y) ? X : (Z ? max(X, Y) : Y) 4602 // If Z is true, this reduces as above, and if Z is false: 4603 // (X > Y) ? X : Y --> max(X, Y) 4604 ICmpInst::Predicate MMPred = MMI->getPredicate(); 4605 if (MMPred == CmpInst::getStrictPredicate(Pred)) 4606 return MMI; 4607 4608 // Other transforms are not valid with a shuffle. 4609 if (PeekedThroughSelectShuffle) 4610 return nullptr; 4611 4612 // (X == Y) ? X : max/min(X, Y) --> max/min(X, Y) 4613 if (Pred == CmpInst::ICMP_EQ) 4614 return MMI; 4615 4616 // (X != Y) ? X : max/min(X, Y) --> X 4617 if (Pred == CmpInst::ICMP_NE) 4618 return X; 4619 4620 // (X < Y) ? X : max(X, Y) --> X 4621 // (X <= Y) ? X : max(X, Y) --> X 4622 // (X > Y) ? X : min(X, Y) --> X 4623 // (X >= Y) ? X : min(X, Y) --> X 4624 ICmpInst::Predicate InvPred = CmpInst::getInversePredicate(Pred); 4625 if (MMPred == CmpInst::getStrictPredicate(InvPred)) 4626 return X; 4627 4628 return nullptr; 4629 } 4630 4631 /// An alternative way to test if a bit is set or not uses sgt/slt instead of 4632 /// eq/ne. 4633 static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS, 4634 ICmpInst::Predicate Pred, 4635 Value *TrueVal, Value *FalseVal) { 4636 if (auto Res = decomposeBitTestICmp(CmpLHS, CmpRHS, Pred)) 4637 return simplifySelectBitTest(TrueVal, FalseVal, Res->X, &Res->Mask, 4638 Res->Pred == ICmpInst::ICMP_EQ); 4639 4640 return nullptr; 4641 } 4642 4643 /// Try to simplify a select instruction when its condition operand is an 4644 /// integer equality or floating-point equivalence comparison. 4645 static Value *simplifySelectWithEquivalence(Value *CmpLHS, Value *CmpRHS, 4646 Value *TrueVal, Value *FalseVal, 4647 const SimplifyQuery &Q, 4648 unsigned MaxRecurse) { 4649 if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q.getWithoutUndef(), 4650 /* AllowRefinement */ false, 4651 /* DropFlags */ nullptr, MaxRecurse) == TrueVal) 4652 return FalseVal; 4653 if (simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, 4654 /* AllowRefinement */ true, 4655 /* DropFlags */ nullptr, MaxRecurse) == FalseVal) 4656 return FalseVal; 4657 4658 return nullptr; 4659 } 4660 4661 /// Try to simplify a select instruction when its condition operand is an 4662 /// integer comparison. 4663 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, 4664 Value *FalseVal, 4665 const SimplifyQuery &Q, 4666 unsigned MaxRecurse) { 4667 ICmpInst::Predicate Pred; 4668 Value *CmpLHS, *CmpRHS; 4669 if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS)))) 4670 return nullptr; 4671 4672 if (Value *V = simplifyCmpSelOfMaxMin(CmpLHS, CmpRHS, Pred, TrueVal, FalseVal)) 4673 return V; 4674 4675 // Canonicalize ne to eq predicate. 4676 if (Pred == ICmpInst::ICMP_NE) { 4677 Pred = ICmpInst::ICMP_EQ; 4678 std::swap(TrueVal, FalseVal); 4679 } 4680 4681 // Check for integer min/max with a limit constant: 4682 // X > MIN_INT ? X : MIN_INT --> X 4683 // X < MAX_INT ? X : MAX_INT --> X 4684 if (TrueVal->getType()->isIntOrIntVectorTy()) { 4685 Value *X, *Y; 4686 SelectPatternFlavor SPF = 4687 matchDecomposedSelectPattern(cast<ICmpInst>(CondVal), TrueVal, FalseVal, 4688 X, Y) 4689 .Flavor; 4690 if (SelectPatternResult::isMinOrMax(SPF) && Pred == getMinMaxPred(SPF)) { 4691 APInt LimitC = getMinMaxLimit(getInverseMinMaxFlavor(SPF), 4692 X->getType()->getScalarSizeInBits()); 4693 if (match(Y, m_SpecificInt(LimitC))) 4694 return X; 4695 } 4696 } 4697 4698 if (Pred == ICmpInst::ICMP_EQ && match(CmpRHS, m_Zero())) { 4699 Value *X; 4700 const APInt *Y; 4701 if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y)))) 4702 if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y, 4703 /*TrueWhenUnset=*/true)) 4704 return V; 4705 4706 // Test for a bogus zero-shift-guard-op around funnel-shift or rotate. 4707 Value *ShAmt; 4708 auto isFsh = m_CombineOr(m_FShl(m_Value(X), m_Value(), m_Value(ShAmt)), 4709 m_FShr(m_Value(), m_Value(X), m_Value(ShAmt))); 4710 // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X 4711 // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X 4712 if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt) 4713 return X; 4714 4715 // Test for a zero-shift-guard-op around rotates. These are used to 4716 // avoid UB from oversized shifts in raw IR rotate patterns, but the 4717 // intrinsics do not have that problem. 4718 // We do not allow this transform for the general funnel shift case because 4719 // that would not preserve the poison safety of the original code. 4720 auto isRotate = 4721 m_CombineOr(m_FShl(m_Value(X), m_Deferred(X), m_Value(ShAmt)), 4722 m_FShr(m_Value(X), m_Deferred(X), m_Value(ShAmt))); 4723 // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt) 4724 // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt) 4725 if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt && 4726 Pred == ICmpInst::ICMP_EQ) 4727 return FalseVal; 4728 4729 // X == 0 ? abs(X) : -abs(X) --> -abs(X) 4730 // X == 0 ? -abs(X) : abs(X) --> abs(X) 4731 if (match(TrueVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))) && 4732 match(FalseVal, m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))))) 4733 return FalseVal; 4734 if (match(TrueVal, 4735 m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) && 4736 match(FalseVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) 4737 return FalseVal; 4738 } 4739 4740 // Check for other compares that behave like bit test. 4741 if (Value *V = 4742 simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred, TrueVal, FalseVal)) 4743 return V; 4744 4745 // If we have a scalar equality comparison, then we know the value in one of 4746 // the arms of the select. See if substituting this value into the arm and 4747 // simplifying the result yields the same value as the other arm. 4748 if (Pred == ICmpInst::ICMP_EQ) { 4749 if (Value *V = simplifySelectWithEquivalence(CmpLHS, CmpRHS, TrueVal, 4750 FalseVal, Q, MaxRecurse)) 4751 return V; 4752 if (Value *V = simplifySelectWithEquivalence(CmpRHS, CmpLHS, TrueVal, 4753 FalseVal, Q, MaxRecurse)) 4754 return V; 4755 4756 Value *X; 4757 Value *Y; 4758 // select((X | Y) == 0 ? X : 0) --> 0 (commuted 2 ways) 4759 if (match(CmpLHS, m_Or(m_Value(X), m_Value(Y))) && 4760 match(CmpRHS, m_Zero())) { 4761 // (X | Y) == 0 implies X == 0 and Y == 0. 4762 if (Value *V = simplifySelectWithEquivalence(X, CmpRHS, TrueVal, FalseVal, 4763 Q, MaxRecurse)) 4764 return V; 4765 if (Value *V = simplifySelectWithEquivalence(Y, CmpRHS, TrueVal, FalseVal, 4766 Q, MaxRecurse)) 4767 return V; 4768 } 4769 4770 // select((X & Y) == -1 ? X : -1) --> -1 (commuted 2 ways) 4771 if (match(CmpLHS, m_And(m_Value(X), m_Value(Y))) && 4772 match(CmpRHS, m_AllOnes())) { 4773 // (X & Y) == -1 implies X == -1 and Y == -1. 4774 if (Value *V = simplifySelectWithEquivalence(X, CmpRHS, TrueVal, FalseVal, 4775 Q, MaxRecurse)) 4776 return V; 4777 if (Value *V = simplifySelectWithEquivalence(Y, CmpRHS, TrueVal, FalseVal, 4778 Q, MaxRecurse)) 4779 return V; 4780 } 4781 } 4782 4783 return nullptr; 4784 } 4785 4786 /// Try to simplify a select instruction when its condition operand is a 4787 /// floating-point comparison. 4788 static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F, 4789 const SimplifyQuery &Q, 4790 unsigned MaxRecurse) { 4791 FCmpInst::Predicate Pred; 4792 Value *CmpLHS, *CmpRHS; 4793 if (!match(Cond, m_FCmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS)))) 4794 return nullptr; 4795 FCmpInst *I = cast<FCmpInst>(Cond); 4796 4797 bool IsEquiv = I->isEquivalence(); 4798 if (I->isEquivalence(/*Invert=*/true)) { 4799 std::swap(T, F); 4800 Pred = FCmpInst::getInversePredicate(Pred); 4801 IsEquiv = true; 4802 } 4803 4804 // This transforms is safe if at least one operand is known to not be zero. 4805 // Otherwise, the select can change the sign of a zero operand. 4806 if (IsEquiv) { 4807 if (Value *V = 4808 simplifySelectWithEquivalence(CmpLHS, CmpRHS, T, F, Q, MaxRecurse)) 4809 return V; 4810 if (Value *V = 4811 simplifySelectWithEquivalence(CmpRHS, CmpLHS, T, F, Q, MaxRecurse)) 4812 return V; 4813 } 4814 4815 // Canonicalize CmpLHS to be T, and CmpRHS to be F, if they're swapped. 4816 if (CmpLHS == F && CmpRHS == T) 4817 std::swap(CmpLHS, CmpRHS); 4818 4819 if (CmpLHS != T || CmpRHS != F) 4820 return nullptr; 4821 4822 // This transform is also safe if we do not have (do not care about) -0.0. 4823 if (Q.CxtI && isa<FPMathOperator>(Q.CxtI) && Q.CxtI->hasNoSignedZeros()) { 4824 // (T == F) ? T : F --> F 4825 if (Pred == FCmpInst::FCMP_OEQ) 4826 return F; 4827 4828 // (T != F) ? T : F --> T 4829 if (Pred == FCmpInst::FCMP_UNE) 4830 return T; 4831 } 4832 4833 return nullptr; 4834 } 4835 4836 /// Given operands for a SelectInst, see if we can fold the result. 4837 /// If not, this returns null. 4838 static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4839 const SimplifyQuery &Q, unsigned MaxRecurse) { 4840 if (auto *CondC = dyn_cast<Constant>(Cond)) { 4841 if (auto *TrueC = dyn_cast<Constant>(TrueVal)) 4842 if (auto *FalseC = dyn_cast<Constant>(FalseVal)) 4843 if (Constant *C = ConstantFoldSelectInstruction(CondC, TrueC, FalseC)) 4844 return C; 4845 4846 // select poison, X, Y -> poison 4847 if (isa<PoisonValue>(CondC)) 4848 return PoisonValue::get(TrueVal->getType()); 4849 4850 // select undef, X, Y -> X or Y 4851 if (Q.isUndefValue(CondC)) 4852 return isa<Constant>(FalseVal) ? FalseVal : TrueVal; 4853 4854 // select true, X, Y --> X 4855 // select false, X, Y --> Y 4856 // For vectors, allow undef/poison elements in the condition to match the 4857 // defined elements, so we can eliminate the select. 4858 if (match(CondC, m_One())) 4859 return TrueVal; 4860 if (match(CondC, m_Zero())) 4861 return FalseVal; 4862 } 4863 4864 assert(Cond->getType()->isIntOrIntVectorTy(1) && 4865 "Select must have bool or bool vector condition"); 4866 assert(TrueVal->getType() == FalseVal->getType() && 4867 "Select must have same types for true/false ops"); 4868 4869 if (Cond->getType() == TrueVal->getType()) { 4870 // select i1 Cond, i1 true, i1 false --> i1 Cond 4871 if (match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt())) 4872 return Cond; 4873 4874 // (X && Y) ? X : Y --> Y (commuted 2 ways) 4875 if (match(Cond, m_c_LogicalAnd(m_Specific(TrueVal), m_Specific(FalseVal)))) 4876 return FalseVal; 4877 4878 // (X || Y) ? X : Y --> X (commuted 2 ways) 4879 if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Specific(FalseVal)))) 4880 return TrueVal; 4881 4882 // (X || Y) ? false : X --> false (commuted 2 ways) 4883 if (match(Cond, m_c_LogicalOr(m_Specific(FalseVal), m_Value())) && 4884 match(TrueVal, m_ZeroInt())) 4885 return ConstantInt::getFalse(Cond->getType()); 4886 4887 // Match patterns that end in logical-and. 4888 if (match(FalseVal, m_ZeroInt())) { 4889 // !(X || Y) && X --> false (commuted 2 ways) 4890 if (match(Cond, m_Not(m_c_LogicalOr(m_Specific(TrueVal), m_Value())))) 4891 return ConstantInt::getFalse(Cond->getType()); 4892 // X && !(X || Y) --> false (commuted 2 ways) 4893 if (match(TrueVal, m_Not(m_c_LogicalOr(m_Specific(Cond), m_Value())))) 4894 return ConstantInt::getFalse(Cond->getType()); 4895 4896 // (X || Y) && Y --> Y (commuted 2 ways) 4897 if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Value()))) 4898 return TrueVal; 4899 // Y && (X || Y) --> Y (commuted 2 ways) 4900 if (match(TrueVal, m_c_LogicalOr(m_Specific(Cond), m_Value()))) 4901 return Cond; 4902 4903 // (X || Y) && (X || !Y) --> X (commuted 8 ways) 4904 Value *X, *Y; 4905 if (match(Cond, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) && 4906 match(TrueVal, m_c_LogicalOr(m_Specific(X), m_Specific(Y)))) 4907 return X; 4908 if (match(TrueVal, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) && 4909 match(Cond, m_c_LogicalOr(m_Specific(X), m_Specific(Y)))) 4910 return X; 4911 } 4912 4913 // Match patterns that end in logical-or. 4914 if (match(TrueVal, m_One())) { 4915 // !(X && Y) || X --> true (commuted 2 ways) 4916 if (match(Cond, m_Not(m_c_LogicalAnd(m_Specific(FalseVal), m_Value())))) 4917 return ConstantInt::getTrue(Cond->getType()); 4918 // X || !(X && Y) --> true (commuted 2 ways) 4919 if (match(FalseVal, m_Not(m_c_LogicalAnd(m_Specific(Cond), m_Value())))) 4920 return ConstantInt::getTrue(Cond->getType()); 4921 4922 // (X && Y) || Y --> Y (commuted 2 ways) 4923 if (match(Cond, m_c_LogicalAnd(m_Specific(FalseVal), m_Value()))) 4924 return FalseVal; 4925 // Y || (X && Y) --> Y (commuted 2 ways) 4926 if (match(FalseVal, m_c_LogicalAnd(m_Specific(Cond), m_Value()))) 4927 return Cond; 4928 } 4929 } 4930 4931 // select ?, X, X -> X 4932 if (TrueVal == FalseVal) 4933 return TrueVal; 4934 4935 if (Cond == TrueVal) { 4936 // select i1 X, i1 X, i1 false --> X (logical-and) 4937 if (match(FalseVal, m_ZeroInt())) 4938 return Cond; 4939 // select i1 X, i1 X, i1 true --> true 4940 if (match(FalseVal, m_One())) 4941 return ConstantInt::getTrue(Cond->getType()); 4942 } 4943 if (Cond == FalseVal) { 4944 // select i1 X, i1 true, i1 X --> X (logical-or) 4945 if (match(TrueVal, m_One())) 4946 return Cond; 4947 // select i1 X, i1 false, i1 X --> false 4948 if (match(TrueVal, m_ZeroInt())) 4949 return ConstantInt::getFalse(Cond->getType()); 4950 } 4951 4952 // If the true or false value is poison, we can fold to the other value. 4953 // If the true or false value is undef, we can fold to the other value as 4954 // long as the other value isn't poison. 4955 // select ?, poison, X -> X 4956 // select ?, undef, X -> X 4957 if (isa<PoisonValue>(TrueVal) || 4958 (Q.isUndefValue(TrueVal) && impliesPoison(FalseVal, Cond))) 4959 return FalseVal; 4960 // select ?, X, poison -> X 4961 // select ?, X, undef -> X 4962 if (isa<PoisonValue>(FalseVal) || 4963 (Q.isUndefValue(FalseVal) && impliesPoison(TrueVal, Cond))) 4964 return TrueVal; 4965 4966 // Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC'' 4967 Constant *TrueC, *FalseC; 4968 if (isa<FixedVectorType>(TrueVal->getType()) && 4969 match(TrueVal, m_Constant(TrueC)) && 4970 match(FalseVal, m_Constant(FalseC))) { 4971 unsigned NumElts = 4972 cast<FixedVectorType>(TrueC->getType())->getNumElements(); 4973 SmallVector<Constant *, 16> NewC; 4974 for (unsigned i = 0; i != NumElts; ++i) { 4975 // Bail out on incomplete vector constants. 4976 Constant *TEltC = TrueC->getAggregateElement(i); 4977 Constant *FEltC = FalseC->getAggregateElement(i); 4978 if (!TEltC || !FEltC) 4979 break; 4980 4981 // If the elements match (undef or not), that value is the result. If only 4982 // one element is undef, choose the defined element as the safe result. 4983 if (TEltC == FEltC) 4984 NewC.push_back(TEltC); 4985 else if (isa<PoisonValue>(TEltC) || 4986 (Q.isUndefValue(TEltC) && isGuaranteedNotToBePoison(FEltC))) 4987 NewC.push_back(FEltC); 4988 else if (isa<PoisonValue>(FEltC) || 4989 (Q.isUndefValue(FEltC) && isGuaranteedNotToBePoison(TEltC))) 4990 NewC.push_back(TEltC); 4991 else 4992 break; 4993 } 4994 if (NewC.size() == NumElts) 4995 return ConstantVector::get(NewC); 4996 } 4997 4998 if (Value *V = 4999 simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse)) 5000 return V; 5001 5002 if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q, MaxRecurse)) 5003 return V; 5004 5005 if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal)) 5006 return V; 5007 5008 std::optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL); 5009 if (Imp) 5010 return *Imp ? TrueVal : FalseVal; 5011 5012 return nullptr; 5013 } 5014 5015 Value *llvm::simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 5016 const SimplifyQuery &Q) { 5017 return ::simplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit); 5018 } 5019 5020 /// Given operands for an GetElementPtrInst, see if we can fold the result. 5021 /// If not, this returns null. 5022 static Value *simplifyGEPInst(Type *SrcTy, Value *Ptr, 5023 ArrayRef<Value *> Indices, GEPNoWrapFlags NW, 5024 const SimplifyQuery &Q, unsigned) { 5025 // The type of the GEP pointer operand. 5026 unsigned AS = 5027 cast<PointerType>(Ptr->getType()->getScalarType())->getAddressSpace(); 5028 5029 // getelementptr P -> P. 5030 if (Indices.empty()) 5031 return Ptr; 5032 5033 // Compute the (pointer) type returned by the GEP instruction. 5034 Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Indices); 5035 Type *GEPTy = Ptr->getType(); 5036 if (!GEPTy->isVectorTy()) { 5037 for (Value *Op : Indices) { 5038 // If one of the operands is a vector, the result type is a vector of 5039 // pointers. All vector operands must have the same number of elements. 5040 if (VectorType *VT = dyn_cast<VectorType>(Op->getType())) { 5041 GEPTy = VectorType::get(GEPTy, VT->getElementCount()); 5042 break; 5043 } 5044 } 5045 } 5046 5047 // All-zero GEP is a no-op, unless it performs a vector splat. 5048 if (Ptr->getType() == GEPTy && 5049 all_of(Indices, [](const auto *V) { return match(V, m_Zero()); })) 5050 return Ptr; 5051 5052 // getelementptr poison, idx -> poison 5053 // getelementptr baseptr, poison -> poison 5054 if (isa<PoisonValue>(Ptr) || 5055 any_of(Indices, [](const auto *V) { return isa<PoisonValue>(V); })) 5056 return PoisonValue::get(GEPTy); 5057 5058 // getelementptr undef, idx -> undef 5059 if (Q.isUndefValue(Ptr)) 5060 return UndefValue::get(GEPTy); 5061 5062 bool IsScalableVec = 5063 SrcTy->isScalableTy() || any_of(Indices, [](const Value *V) { 5064 return isa<ScalableVectorType>(V->getType()); 5065 }); 5066 5067 if (Indices.size() == 1) { 5068 Type *Ty = SrcTy; 5069 if (!IsScalableVec && Ty->isSized()) { 5070 Value *P; 5071 uint64_t C; 5072 uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty); 5073 // getelementptr P, N -> P if P points to a type of zero size. 5074 if (TyAllocSize == 0 && Ptr->getType() == GEPTy) 5075 return Ptr; 5076 5077 // The following transforms are only safe if the ptrtoint cast 5078 // doesn't truncate the pointers. 5079 if (Indices[0]->getType()->getScalarSizeInBits() == 5080 Q.DL.getPointerSizeInBits(AS)) { 5081 auto CanSimplify = [GEPTy, &P, Ptr]() -> bool { 5082 return P->getType() == GEPTy && 5083 getUnderlyingObject(P) == getUnderlyingObject(Ptr); 5084 }; 5085 // getelementptr V, (sub P, V) -> P if P points to a type of size 1. 5086 if (TyAllocSize == 1 && 5087 match(Indices[0], 5088 m_Sub(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Specific(Ptr)))) && 5089 CanSimplify()) 5090 return P; 5091 5092 // getelementptr V, (ashr (sub P, V), C) -> P if P points to a type of 5093 // size 1 << C. 5094 if (match(Indices[0], m_AShr(m_Sub(m_PtrToInt(m_Value(P)), 5095 m_PtrToInt(m_Specific(Ptr))), 5096 m_ConstantInt(C))) && 5097 TyAllocSize == 1ULL << C && CanSimplify()) 5098 return P; 5099 5100 // getelementptr V, (sdiv (sub P, V), C) -> P if P points to a type of 5101 // size C. 5102 if (match(Indices[0], m_SDiv(m_Sub(m_PtrToInt(m_Value(P)), 5103 m_PtrToInt(m_Specific(Ptr))), 5104 m_SpecificInt(TyAllocSize))) && 5105 CanSimplify()) 5106 return P; 5107 } 5108 } 5109 } 5110 5111 if (!IsScalableVec && Q.DL.getTypeAllocSize(LastType) == 1 && 5112 all_of(Indices.drop_back(1), 5113 [](Value *Idx) { return match(Idx, m_Zero()); })) { 5114 unsigned IdxWidth = 5115 Q.DL.getIndexSizeInBits(Ptr->getType()->getPointerAddressSpace()); 5116 if (Q.DL.getTypeSizeInBits(Indices.back()->getType()) == IdxWidth) { 5117 APInt BasePtrOffset(IdxWidth, 0); 5118 Value *StrippedBasePtr = 5119 Ptr->stripAndAccumulateInBoundsConstantOffsets(Q.DL, BasePtrOffset); 5120 5121 // Avoid creating inttoptr of zero here: While LLVMs treatment of 5122 // inttoptr is generally conservative, this particular case is folded to 5123 // a null pointer, which will have incorrect provenance. 5124 5125 // gep (gep V, C), (sub 0, V) -> C 5126 if (match(Indices.back(), 5127 m_Neg(m_PtrToInt(m_Specific(StrippedBasePtr)))) && 5128 !BasePtrOffset.isZero()) { 5129 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset); 5130 return ConstantExpr::getIntToPtr(CI, GEPTy); 5131 } 5132 // gep (gep V, C), (xor V, -1) -> C-1 5133 if (match(Indices.back(), 5134 m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes())) && 5135 !BasePtrOffset.isOne()) { 5136 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1); 5137 return ConstantExpr::getIntToPtr(CI, GEPTy); 5138 } 5139 } 5140 } 5141 5142 // Check to see if this is constant foldable. 5143 if (!isa<Constant>(Ptr) || 5144 !all_of(Indices, [](Value *V) { return isa<Constant>(V); })) 5145 return nullptr; 5146 5147 if (!ConstantExpr::isSupportedGetElementPtr(SrcTy)) 5148 return ConstantFoldGetElementPtr(SrcTy, cast<Constant>(Ptr), std::nullopt, 5149 Indices); 5150 5151 auto *CE = 5152 ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ptr), Indices, NW); 5153 return ConstantFoldConstant(CE, Q.DL); 5154 } 5155 5156 Value *llvm::simplifyGEPInst(Type *SrcTy, Value *Ptr, ArrayRef<Value *> Indices, 5157 GEPNoWrapFlags NW, const SimplifyQuery &Q) { 5158 return ::simplifyGEPInst(SrcTy, Ptr, Indices, NW, Q, RecursionLimit); 5159 } 5160 5161 /// Given operands for an InsertValueInst, see if we can fold the result. 5162 /// If not, this returns null. 5163 static Value *simplifyInsertValueInst(Value *Agg, Value *Val, 5164 ArrayRef<unsigned> Idxs, 5165 const SimplifyQuery &Q, unsigned) { 5166 if (Constant *CAgg = dyn_cast<Constant>(Agg)) 5167 if (Constant *CVal = dyn_cast<Constant>(Val)) 5168 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); 5169 5170 // insertvalue x, poison, n -> x 5171 // insertvalue x, undef, n -> x if x cannot be poison 5172 if (isa<PoisonValue>(Val) || 5173 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Agg))) 5174 return Agg; 5175 5176 // insertvalue x, (extractvalue y, n), n 5177 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) 5178 if (EV->getAggregateOperand()->getType() == Agg->getType() && 5179 EV->getIndices() == Idxs) { 5180 // insertvalue poison, (extractvalue y, n), n -> y 5181 // insertvalue undef, (extractvalue y, n), n -> y if y cannot be poison 5182 if (isa<PoisonValue>(Agg) || 5183 (Q.isUndefValue(Agg) && 5184 isGuaranteedNotToBePoison(EV->getAggregateOperand()))) 5185 return EV->getAggregateOperand(); 5186 5187 // insertvalue y, (extractvalue y, n), n -> y 5188 if (Agg == EV->getAggregateOperand()) 5189 return Agg; 5190 } 5191 5192 return nullptr; 5193 } 5194 5195 Value *llvm::simplifyInsertValueInst(Value *Agg, Value *Val, 5196 ArrayRef<unsigned> Idxs, 5197 const SimplifyQuery &Q) { 5198 return ::simplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit); 5199 } 5200 5201 Value *llvm::simplifyInsertElementInst(Value *Vec, Value *Val, Value *Idx, 5202 const SimplifyQuery &Q) { 5203 // Try to constant fold. 5204 auto *VecC = dyn_cast<Constant>(Vec); 5205 auto *ValC = dyn_cast<Constant>(Val); 5206 auto *IdxC = dyn_cast<Constant>(Idx); 5207 if (VecC && ValC && IdxC) 5208 return ConstantExpr::getInsertElement(VecC, ValC, IdxC); 5209 5210 // For fixed-length vector, fold into poison if index is out of bounds. 5211 if (auto *CI = dyn_cast<ConstantInt>(Idx)) { 5212 if (isa<FixedVectorType>(Vec->getType()) && 5213 CI->uge(cast<FixedVectorType>(Vec->getType())->getNumElements())) 5214 return PoisonValue::get(Vec->getType()); 5215 } 5216 5217 // If index is undef, it might be out of bounds (see above case) 5218 if (Q.isUndefValue(Idx)) 5219 return PoisonValue::get(Vec->getType()); 5220 5221 // If the scalar is poison, or it is undef and there is no risk of 5222 // propagating poison from the vector value, simplify to the vector value. 5223 if (isa<PoisonValue>(Val) || 5224 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Vec))) 5225 return Vec; 5226 5227 // Inserting the splatted value into a constant splat does nothing. 5228 if (VecC && ValC && VecC->getSplatValue() == ValC) 5229 return Vec; 5230 5231 // If we are extracting a value from a vector, then inserting it into the same 5232 // place, that's the input vector: 5233 // insertelt Vec, (extractelt Vec, Idx), Idx --> Vec 5234 if (match(Val, m_ExtractElt(m_Specific(Vec), m_Specific(Idx)))) 5235 return Vec; 5236 5237 return nullptr; 5238 } 5239 5240 /// Given operands for an ExtractValueInst, see if we can fold the result. 5241 /// If not, this returns null. 5242 static Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 5243 const SimplifyQuery &, unsigned) { 5244 if (auto *CAgg = dyn_cast<Constant>(Agg)) 5245 return ConstantFoldExtractValueInstruction(CAgg, Idxs); 5246 5247 // extractvalue x, (insertvalue y, elt, n), n -> elt 5248 unsigned NumIdxs = Idxs.size(); 5249 for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr; 5250 IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) { 5251 ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices(); 5252 unsigned NumInsertValueIdxs = InsertValueIdxs.size(); 5253 unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs); 5254 if (InsertValueIdxs.slice(0, NumCommonIdxs) == 5255 Idxs.slice(0, NumCommonIdxs)) { 5256 if (NumIdxs == NumInsertValueIdxs) 5257 return IVI->getInsertedValueOperand(); 5258 break; 5259 } 5260 } 5261 5262 return nullptr; 5263 } 5264 5265 Value *llvm::simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 5266 const SimplifyQuery &Q) { 5267 return ::simplifyExtractValueInst(Agg, Idxs, Q, RecursionLimit); 5268 } 5269 5270 /// Given operands for an ExtractElementInst, see if we can fold the result. 5271 /// If not, this returns null. 5272 static Value *simplifyExtractElementInst(Value *Vec, Value *Idx, 5273 const SimplifyQuery &Q, unsigned) { 5274 auto *VecVTy = cast<VectorType>(Vec->getType()); 5275 if (auto *CVec = dyn_cast<Constant>(Vec)) { 5276 if (auto *CIdx = dyn_cast<Constant>(Idx)) 5277 return ConstantExpr::getExtractElement(CVec, CIdx); 5278 5279 if (Q.isUndefValue(Vec)) 5280 return UndefValue::get(VecVTy->getElementType()); 5281 } 5282 5283 // An undef extract index can be arbitrarily chosen to be an out-of-range 5284 // index value, which would result in the instruction being poison. 5285 if (Q.isUndefValue(Idx)) 5286 return PoisonValue::get(VecVTy->getElementType()); 5287 5288 // If extracting a specified index from the vector, see if we can recursively 5289 // find a previously computed scalar that was inserted into the vector. 5290 if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) { 5291 // For fixed-length vector, fold into undef if index is out of bounds. 5292 unsigned MinNumElts = VecVTy->getElementCount().getKnownMinValue(); 5293 if (isa<FixedVectorType>(VecVTy) && IdxC->getValue().uge(MinNumElts)) 5294 return PoisonValue::get(VecVTy->getElementType()); 5295 // Handle case where an element is extracted from a splat. 5296 if (IdxC->getValue().ult(MinNumElts)) 5297 if (auto *Splat = getSplatValue(Vec)) 5298 return Splat; 5299 if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue())) 5300 return Elt; 5301 } else { 5302 // extractelt x, (insertelt y, elt, n), n -> elt 5303 // If the possibly-variable indices are trivially known to be equal 5304 // (because they are the same operand) then use the value that was 5305 // inserted directly. 5306 auto *IE = dyn_cast<InsertElementInst>(Vec); 5307 if (IE && IE->getOperand(2) == Idx) 5308 return IE->getOperand(1); 5309 5310 // The index is not relevant if our vector is a splat. 5311 if (Value *Splat = getSplatValue(Vec)) 5312 return Splat; 5313 } 5314 return nullptr; 5315 } 5316 5317 Value *llvm::simplifyExtractElementInst(Value *Vec, Value *Idx, 5318 const SimplifyQuery &Q) { 5319 return ::simplifyExtractElementInst(Vec, Idx, Q, RecursionLimit); 5320 } 5321 5322 /// See if we can fold the given phi. If not, returns null. 5323 static Value *simplifyPHINode(PHINode *PN, ArrayRef<Value *> IncomingValues, 5324 const SimplifyQuery &Q) { 5325 // WARNING: no matter how worthwhile it may seem, we can not perform PHI CSE 5326 // here, because the PHI we may succeed simplifying to was not 5327 // def-reachable from the original PHI! 5328 5329 // If all of the PHI's incoming values are the same then replace the PHI node 5330 // with the common value. 5331 Value *CommonValue = nullptr; 5332 bool HasPoisonInput = false; 5333 bool HasUndefInput = false; 5334 for (Value *Incoming : IncomingValues) { 5335 // If the incoming value is the phi node itself, it can safely be skipped. 5336 if (Incoming == PN) 5337 continue; 5338 if (isa<PoisonValue>(Incoming)) { 5339 HasPoisonInput = true; 5340 continue; 5341 } 5342 if (Q.isUndefValue(Incoming)) { 5343 // Remember that we saw an undef value, but otherwise ignore them. 5344 HasUndefInput = true; 5345 continue; 5346 } 5347 if (CommonValue && Incoming != CommonValue) 5348 return nullptr; // Not the same, bail out. 5349 CommonValue = Incoming; 5350 } 5351 5352 // If CommonValue is null then all of the incoming values were either undef, 5353 // poison or equal to the phi node itself. 5354 if (!CommonValue) 5355 return HasUndefInput ? UndefValue::get(PN->getType()) 5356 : PoisonValue::get(PN->getType()); 5357 5358 if (HasPoisonInput || HasUndefInput) { 5359 // If we have a PHI node like phi(X, undef, X), where X is defined by some 5360 // instruction, we cannot return X as the result of the PHI node unless it 5361 // dominates the PHI block. 5362 if (!valueDominatesPHI(CommonValue, PN, Q.DT)) 5363 return nullptr; 5364 5365 // Make sure we do not replace an undef value with poison. 5366 if (HasUndefInput && 5367 !isGuaranteedNotToBePoison(CommonValue, Q.AC, Q.CxtI, Q.DT)) 5368 return nullptr; 5369 return CommonValue; 5370 } 5371 5372 return CommonValue; 5373 } 5374 5375 static Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 5376 const SimplifyQuery &Q, unsigned MaxRecurse) { 5377 if (auto *C = dyn_cast<Constant>(Op)) 5378 return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL); 5379 5380 if (auto *CI = dyn_cast<CastInst>(Op)) { 5381 auto *Src = CI->getOperand(0); 5382 Type *SrcTy = Src->getType(); 5383 Type *MidTy = CI->getType(); 5384 Type *DstTy = Ty; 5385 if (Src->getType() == Ty) { 5386 auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode()); 5387 auto SecondOp = static_cast<Instruction::CastOps>(CastOpc); 5388 Type *SrcIntPtrTy = 5389 SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr; 5390 Type *MidIntPtrTy = 5391 MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr; 5392 Type *DstIntPtrTy = 5393 DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr; 5394 if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy, 5395 SrcIntPtrTy, MidIntPtrTy, 5396 DstIntPtrTy) == Instruction::BitCast) 5397 return Src; 5398 } 5399 } 5400 5401 // bitcast x -> x 5402 if (CastOpc == Instruction::BitCast) 5403 if (Op->getType() == Ty) 5404 return Op; 5405 5406 // ptrtoint (ptradd (Ptr, X - ptrtoint(Ptr))) -> X 5407 Value *Ptr, *X; 5408 if (CastOpc == Instruction::PtrToInt && 5409 match(Op, m_PtrAdd(m_Value(Ptr), 5410 m_Sub(m_Value(X), m_PtrToInt(m_Deferred(Ptr))))) && 5411 X->getType() == Ty && Ty == Q.DL.getIndexType(Ptr->getType())) 5412 return X; 5413 5414 return nullptr; 5415 } 5416 5417 Value *llvm::simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 5418 const SimplifyQuery &Q) { 5419 return ::simplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit); 5420 } 5421 5422 /// For the given destination element of a shuffle, peek through shuffles to 5423 /// match a root vector source operand that contains that element in the same 5424 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s). 5425 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1, 5426 int MaskVal, Value *RootVec, 5427 unsigned MaxRecurse) { 5428 if (!MaxRecurse--) 5429 return nullptr; 5430 5431 // Bail out if any mask value is undefined. That kind of shuffle may be 5432 // simplified further based on demanded bits or other folds. 5433 if (MaskVal == -1) 5434 return nullptr; 5435 5436 // The mask value chooses which source operand we need to look at next. 5437 int InVecNumElts = cast<FixedVectorType>(Op0->getType())->getNumElements(); 5438 int RootElt = MaskVal; 5439 Value *SourceOp = Op0; 5440 if (MaskVal >= InVecNumElts) { 5441 RootElt = MaskVal - InVecNumElts; 5442 SourceOp = Op1; 5443 } 5444 5445 // If the source operand is a shuffle itself, look through it to find the 5446 // matching root vector. 5447 if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) { 5448 return foldIdentityShuffles( 5449 DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1), 5450 SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse); 5451 } 5452 5453 // The source operand is not a shuffle. Initialize the root vector value for 5454 // this shuffle if that has not been done yet. 5455 if (!RootVec) 5456 RootVec = SourceOp; 5457 5458 // Give up as soon as a source operand does not match the existing root value. 5459 if (RootVec != SourceOp) 5460 return nullptr; 5461 5462 // The element must be coming from the same lane in the source vector 5463 // (although it may have crossed lanes in intermediate shuffles). 5464 if (RootElt != DestElt) 5465 return nullptr; 5466 5467 return RootVec; 5468 } 5469 5470 static Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1, 5471 ArrayRef<int> Mask, Type *RetTy, 5472 const SimplifyQuery &Q, 5473 unsigned MaxRecurse) { 5474 if (all_of(Mask, [](int Elem) { return Elem == PoisonMaskElem; })) 5475 return PoisonValue::get(RetTy); 5476 5477 auto *InVecTy = cast<VectorType>(Op0->getType()); 5478 unsigned MaskNumElts = Mask.size(); 5479 ElementCount InVecEltCount = InVecTy->getElementCount(); 5480 5481 bool Scalable = InVecEltCount.isScalable(); 5482 5483 SmallVector<int, 32> Indices; 5484 Indices.assign(Mask.begin(), Mask.end()); 5485 5486 // Canonicalization: If mask does not select elements from an input vector, 5487 // replace that input vector with poison. 5488 if (!Scalable) { 5489 bool MaskSelects0 = false, MaskSelects1 = false; 5490 unsigned InVecNumElts = InVecEltCount.getKnownMinValue(); 5491 for (unsigned i = 0; i != MaskNumElts; ++i) { 5492 if (Indices[i] == -1) 5493 continue; 5494 if ((unsigned)Indices[i] < InVecNumElts) 5495 MaskSelects0 = true; 5496 else 5497 MaskSelects1 = true; 5498 } 5499 if (!MaskSelects0) 5500 Op0 = PoisonValue::get(InVecTy); 5501 if (!MaskSelects1) 5502 Op1 = PoisonValue::get(InVecTy); 5503 } 5504 5505 auto *Op0Const = dyn_cast<Constant>(Op0); 5506 auto *Op1Const = dyn_cast<Constant>(Op1); 5507 5508 // If all operands are constant, constant fold the shuffle. This 5509 // transformation depends on the value of the mask which is not known at 5510 // compile time for scalable vectors 5511 if (Op0Const && Op1Const) 5512 return ConstantExpr::getShuffleVector(Op0Const, Op1Const, Mask); 5513 5514 // Canonicalization: if only one input vector is constant, it shall be the 5515 // second one. This transformation depends on the value of the mask which 5516 // is not known at compile time for scalable vectors 5517 if (!Scalable && Op0Const && !Op1Const) { 5518 std::swap(Op0, Op1); 5519 ShuffleVectorInst::commuteShuffleMask(Indices, 5520 InVecEltCount.getKnownMinValue()); 5521 } 5522 5523 // A splat of an inserted scalar constant becomes a vector constant: 5524 // shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...> 5525 // NOTE: We may have commuted above, so analyze the updated Indices, not the 5526 // original mask constant. 5527 // NOTE: This transformation depends on the value of the mask which is not 5528 // known at compile time for scalable vectors 5529 Constant *C; 5530 ConstantInt *IndexC; 5531 if (!Scalable && match(Op0, m_InsertElt(m_Value(), m_Constant(C), 5532 m_ConstantInt(IndexC)))) { 5533 // Match a splat shuffle mask of the insert index allowing undef elements. 5534 int InsertIndex = IndexC->getZExtValue(); 5535 if (all_of(Indices, [InsertIndex](int MaskElt) { 5536 return MaskElt == InsertIndex || MaskElt == -1; 5537 })) { 5538 assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat"); 5539 5540 // Shuffle mask poisons become poison constant result elements. 5541 SmallVector<Constant *, 16> VecC(MaskNumElts, C); 5542 for (unsigned i = 0; i != MaskNumElts; ++i) 5543 if (Indices[i] == -1) 5544 VecC[i] = PoisonValue::get(C->getType()); 5545 return ConstantVector::get(VecC); 5546 } 5547 } 5548 5549 // A shuffle of a splat is always the splat itself. Legal if the shuffle's 5550 // value type is same as the input vectors' type. 5551 if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0)) 5552 if (Q.isUndefValue(Op1) && RetTy == InVecTy && 5553 all_equal(OpShuf->getShuffleMask())) 5554 return Op0; 5555 5556 // All remaining transformation depend on the value of the mask, which is 5557 // not known at compile time for scalable vectors. 5558 if (Scalable) 5559 return nullptr; 5560 5561 // Don't fold a shuffle with undef mask elements. This may get folded in a 5562 // better way using demanded bits or other analysis. 5563 // TODO: Should we allow this? 5564 if (is_contained(Indices, -1)) 5565 return nullptr; 5566 5567 // Check if every element of this shuffle can be mapped back to the 5568 // corresponding element of a single root vector. If so, we don't need this 5569 // shuffle. This handles simple identity shuffles as well as chains of 5570 // shuffles that may widen/narrow and/or move elements across lanes and back. 5571 Value *RootVec = nullptr; 5572 for (unsigned i = 0; i != MaskNumElts; ++i) { 5573 // Note that recursion is limited for each vector element, so if any element 5574 // exceeds the limit, this will fail to simplify. 5575 RootVec = 5576 foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse); 5577 5578 // We can't replace a widening/narrowing shuffle with one of its operands. 5579 if (!RootVec || RootVec->getType() != RetTy) 5580 return nullptr; 5581 } 5582 return RootVec; 5583 } 5584 5585 /// Given operands for a ShuffleVectorInst, fold the result or return null. 5586 Value *llvm::simplifyShuffleVectorInst(Value *Op0, Value *Op1, 5587 ArrayRef<int> Mask, Type *RetTy, 5588 const SimplifyQuery &Q) { 5589 return ::simplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit); 5590 } 5591 5592 static Constant *foldConstant(Instruction::UnaryOps Opcode, Value *&Op, 5593 const SimplifyQuery &Q) { 5594 if (auto *C = dyn_cast<Constant>(Op)) 5595 return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL); 5596 return nullptr; 5597 } 5598 5599 /// Given the operand for an FNeg, see if we can fold the result. If not, this 5600 /// returns null. 5601 static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, 5602 const SimplifyQuery &Q, unsigned MaxRecurse) { 5603 if (Constant *C = foldConstant(Instruction::FNeg, Op, Q)) 5604 return C; 5605 5606 Value *X; 5607 // fneg (fneg X) ==> X 5608 if (match(Op, m_FNeg(m_Value(X)))) 5609 return X; 5610 5611 return nullptr; 5612 } 5613 5614 Value *llvm::simplifyFNegInst(Value *Op, FastMathFlags FMF, 5615 const SimplifyQuery &Q) { 5616 return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit); 5617 } 5618 5619 /// Try to propagate existing NaN values when possible. If not, replace the 5620 /// constant or elements in the constant with a canonical NaN. 5621 static Constant *propagateNaN(Constant *In) { 5622 Type *Ty = In->getType(); 5623 if (auto *VecTy = dyn_cast<FixedVectorType>(Ty)) { 5624 unsigned NumElts = VecTy->getNumElements(); 5625 SmallVector<Constant *, 32> NewC(NumElts); 5626 for (unsigned i = 0; i != NumElts; ++i) { 5627 Constant *EltC = In->getAggregateElement(i); 5628 // Poison elements propagate. NaN propagates except signaling is quieted. 5629 // Replace unknown or undef elements with canonical NaN. 5630 if (EltC && isa<PoisonValue>(EltC)) 5631 NewC[i] = EltC; 5632 else if (EltC && EltC->isNaN()) 5633 NewC[i] = ConstantFP::get( 5634 EltC->getType(), cast<ConstantFP>(EltC)->getValue().makeQuiet()); 5635 else 5636 NewC[i] = ConstantFP::getNaN(VecTy->getElementType()); 5637 } 5638 return ConstantVector::get(NewC); 5639 } 5640 5641 // If it is not a fixed vector, but not a simple NaN either, return a 5642 // canonical NaN. 5643 if (!In->isNaN()) 5644 return ConstantFP::getNaN(Ty); 5645 5646 // If we known this is a NaN, and it's scalable vector, we must have a splat 5647 // on our hands. Grab that before splatting a QNaN constant. 5648 if (isa<ScalableVectorType>(Ty)) { 5649 auto *Splat = In->getSplatValue(); 5650 assert(Splat && Splat->isNaN() && 5651 "Found a scalable-vector NaN but not a splat"); 5652 In = Splat; 5653 } 5654 5655 // Propagate an existing QNaN constant. If it is an SNaN, make it quiet, but 5656 // preserve the sign/payload. 5657 return ConstantFP::get(Ty, cast<ConstantFP>(In)->getValue().makeQuiet()); 5658 } 5659 5660 /// Perform folds that are common to any floating-point operation. This implies 5661 /// transforms based on poison/undef/NaN because the operation itself makes no 5662 /// difference to the result. 5663 static Constant *simplifyFPOp(ArrayRef<Value *> Ops, FastMathFlags FMF, 5664 const SimplifyQuery &Q, 5665 fp::ExceptionBehavior ExBehavior, 5666 RoundingMode Rounding) { 5667 // Poison is independent of anything else. It always propagates from an 5668 // operand to a math result. 5669 if (any_of(Ops, [](Value *V) { return match(V, m_Poison()); })) 5670 return PoisonValue::get(Ops[0]->getType()); 5671 5672 for (Value *V : Ops) { 5673 bool IsNan = match(V, m_NaN()); 5674 bool IsInf = match(V, m_Inf()); 5675 bool IsUndef = Q.isUndefValue(V); 5676 5677 // If this operation has 'nnan' or 'ninf' and at least 1 disallowed operand 5678 // (an undef operand can be chosen to be Nan/Inf), then the result of 5679 // this operation is poison. 5680 if (FMF.noNaNs() && (IsNan || IsUndef)) 5681 return PoisonValue::get(V->getType()); 5682 if (FMF.noInfs() && (IsInf || IsUndef)) 5683 return PoisonValue::get(V->getType()); 5684 5685 if (isDefaultFPEnvironment(ExBehavior, Rounding)) { 5686 // Undef does not propagate because undef means that all bits can take on 5687 // any value. If this is undef * NaN for example, then the result values 5688 // (at least the exponent bits) are limited. Assume the undef is a 5689 // canonical NaN and propagate that. 5690 if (IsUndef) 5691 return ConstantFP::getNaN(V->getType()); 5692 if (IsNan) 5693 return propagateNaN(cast<Constant>(V)); 5694 } else if (ExBehavior != fp::ebStrict) { 5695 if (IsNan) 5696 return propagateNaN(cast<Constant>(V)); 5697 } 5698 } 5699 return nullptr; 5700 } 5701 5702 /// Given operands for an FAdd, see if we can fold the result. If not, this 5703 /// returns null. 5704 static Value * 5705 simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5706 const SimplifyQuery &Q, unsigned MaxRecurse, 5707 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5708 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5709 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5710 if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q)) 5711 return C; 5712 5713 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5714 return C; 5715 5716 // fadd X, -0 ==> X 5717 // With strict/constrained FP, we have these possible edge cases that do 5718 // not simplify to Op0: 5719 // fadd SNaN, -0.0 --> QNaN 5720 // fadd +0.0, -0.0 --> -0.0 (but only with round toward negative) 5721 if (canIgnoreSNaN(ExBehavior, FMF) && 5722 (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) || 5723 FMF.noSignedZeros())) 5724 if (match(Op1, m_NegZeroFP())) 5725 return Op0; 5726 5727 // fadd X, 0 ==> X, when we know X is not -0 5728 if (canIgnoreSNaN(ExBehavior, FMF)) 5729 if (match(Op1, m_PosZeroFP()) && 5730 (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, /*Depth=*/0, Q))) 5731 return Op0; 5732 5733 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5734 return nullptr; 5735 5736 if (FMF.noNaNs()) { 5737 // With nnan: X + {+/-}Inf --> {+/-}Inf 5738 if (match(Op1, m_Inf())) 5739 return Op1; 5740 5741 // With nnan: -X + X --> 0.0 (and commuted variant) 5742 // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN. 5743 // Negative zeros are allowed because we always end up with positive zero: 5744 // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 5745 // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 5746 // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0 5747 // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0 5748 if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || 5749 match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))) 5750 return ConstantFP::getZero(Op0->getType()); 5751 5752 if (match(Op0, m_FNeg(m_Specific(Op1))) || 5753 match(Op1, m_FNeg(m_Specific(Op0)))) 5754 return ConstantFP::getZero(Op0->getType()); 5755 } 5756 5757 // (X - Y) + Y --> X 5758 // Y + (X - Y) --> X 5759 Value *X; 5760 if (FMF.noSignedZeros() && FMF.allowReassoc() && 5761 (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) || 5762 match(Op1, m_FSub(m_Value(X), m_Specific(Op0))))) 5763 return X; 5764 5765 return nullptr; 5766 } 5767 5768 /// Given operands for an FSub, see if we can fold the result. If not, this 5769 /// returns null. 5770 static Value * 5771 simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5772 const SimplifyQuery &Q, unsigned MaxRecurse, 5773 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5774 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5775 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5776 if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q)) 5777 return C; 5778 5779 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5780 return C; 5781 5782 // fsub X, +0 ==> X 5783 if (canIgnoreSNaN(ExBehavior, FMF) && 5784 (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) || 5785 FMF.noSignedZeros())) 5786 if (match(Op1, m_PosZeroFP())) 5787 return Op0; 5788 5789 // fsub X, -0 ==> X, when we know X is not -0 5790 if (canIgnoreSNaN(ExBehavior, FMF)) 5791 if (match(Op1, m_NegZeroFP()) && 5792 (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, /*Depth=*/0, Q))) 5793 return Op0; 5794 5795 // fsub -0.0, (fsub -0.0, X) ==> X 5796 // fsub -0.0, (fneg X) ==> X 5797 Value *X; 5798 if (canIgnoreSNaN(ExBehavior, FMF)) 5799 if (match(Op0, m_NegZeroFP()) && match(Op1, m_FNeg(m_Value(X)))) 5800 return X; 5801 5802 // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored. 5803 // fsub 0.0, (fneg X) ==> X if signed zeros are ignored. 5804 if (canIgnoreSNaN(ExBehavior, FMF)) 5805 if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) && 5806 (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) || 5807 match(Op1, m_FNeg(m_Value(X))))) 5808 return X; 5809 5810 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5811 return nullptr; 5812 5813 if (FMF.noNaNs()) { 5814 // fsub nnan x, x ==> 0.0 5815 if (Op0 == Op1) 5816 return Constant::getNullValue(Op0->getType()); 5817 5818 // With nnan: {+/-}Inf - X --> {+/-}Inf 5819 if (match(Op0, m_Inf())) 5820 return Op0; 5821 5822 // With nnan: X - {+/-}Inf --> {-/+}Inf 5823 if (match(Op1, m_Inf())) 5824 return foldConstant(Instruction::FNeg, Op1, Q); 5825 } 5826 5827 // Y - (Y - X) --> X 5828 // (X + Y) - Y --> X 5829 if (FMF.noSignedZeros() && FMF.allowReassoc() && 5830 (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) || 5831 match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X))))) 5832 return X; 5833 5834 return nullptr; 5835 } 5836 5837 static Value *simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 5838 const SimplifyQuery &Q, unsigned MaxRecurse, 5839 fp::ExceptionBehavior ExBehavior, 5840 RoundingMode Rounding) { 5841 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5842 return C; 5843 5844 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5845 return nullptr; 5846 5847 // Canonicalize special constants as operand 1. 5848 if (match(Op0, m_FPOne()) || match(Op0, m_AnyZeroFP())) 5849 std::swap(Op0, Op1); 5850 5851 // X * 1.0 --> X 5852 if (match(Op1, m_FPOne())) 5853 return Op0; 5854 5855 if (match(Op1, m_AnyZeroFP())) { 5856 // X * 0.0 --> 0.0 (with nnan and nsz) 5857 if (FMF.noNaNs() && FMF.noSignedZeros()) 5858 return ConstantFP::getZero(Op0->getType()); 5859 5860 KnownFPClass Known = 5861 computeKnownFPClass(Op0, FMF, fcInf | fcNan, /*Depth=*/0, Q); 5862 if (Known.isKnownNever(fcInf | fcNan)) { 5863 // +normal number * (-)0.0 --> (-)0.0 5864 if (Known.SignBit == false) 5865 return Op1; 5866 // -normal number * (-)0.0 --> -(-)0.0 5867 if (Known.SignBit == true) 5868 return foldConstant(Instruction::FNeg, Op1, Q); 5869 } 5870 } 5871 5872 // sqrt(X) * sqrt(X) --> X, if we can: 5873 // 1. Remove the intermediate rounding (reassociate). 5874 // 2. Ignore non-zero negative numbers because sqrt would produce NAN. 5875 // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0. 5876 Value *X; 5877 if (Op0 == Op1 && match(Op0, m_Sqrt(m_Value(X))) && FMF.allowReassoc() && 5878 FMF.noNaNs() && FMF.noSignedZeros()) 5879 return X; 5880 5881 return nullptr; 5882 } 5883 5884 /// Given the operands for an FMul, see if we can fold the result 5885 static Value * 5886 simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5887 const SimplifyQuery &Q, unsigned MaxRecurse, 5888 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5889 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5890 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5891 if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q)) 5892 return C; 5893 5894 // Now apply simplifications that do not require rounding. 5895 return simplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse, ExBehavior, Rounding); 5896 } 5897 5898 Value *llvm::simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5899 const SimplifyQuery &Q, 5900 fp::ExceptionBehavior ExBehavior, 5901 RoundingMode Rounding) { 5902 return ::simplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5903 Rounding); 5904 } 5905 5906 Value *llvm::simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5907 const SimplifyQuery &Q, 5908 fp::ExceptionBehavior ExBehavior, 5909 RoundingMode Rounding) { 5910 return ::simplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5911 Rounding); 5912 } 5913 5914 Value *llvm::simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5915 const SimplifyQuery &Q, 5916 fp::ExceptionBehavior ExBehavior, 5917 RoundingMode Rounding) { 5918 return ::simplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5919 Rounding); 5920 } 5921 5922 Value *llvm::simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 5923 const SimplifyQuery &Q, 5924 fp::ExceptionBehavior ExBehavior, 5925 RoundingMode Rounding) { 5926 return ::simplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5927 Rounding); 5928 } 5929 5930 static Value * 5931 simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5932 const SimplifyQuery &Q, unsigned, 5933 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5934 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5935 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5936 if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q)) 5937 return C; 5938 5939 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5940 return C; 5941 5942 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5943 return nullptr; 5944 5945 // X / 1.0 -> X 5946 if (match(Op1, m_FPOne())) 5947 return Op0; 5948 5949 // 0 / X -> 0 5950 // Requires that NaNs are off (X could be zero) and signed zeroes are 5951 // ignored (X could be positive or negative, so the output sign is unknown). 5952 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) 5953 return ConstantFP::getZero(Op0->getType()); 5954 5955 if (FMF.noNaNs()) { 5956 // X / X -> 1.0 is legal when NaNs are ignored. 5957 // We can ignore infinities because INF/INF is NaN. 5958 if (Op0 == Op1) 5959 return ConstantFP::get(Op0->getType(), 1.0); 5960 5961 // (X * Y) / Y --> X if we can reassociate to the above form. 5962 Value *X; 5963 if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1)))) 5964 return X; 5965 5966 // -X / X -> -1.0 and 5967 // X / -X -> -1.0 are legal when NaNs are ignored. 5968 // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored. 5969 if (match(Op0, m_FNegNSZ(m_Specific(Op1))) || 5970 match(Op1, m_FNegNSZ(m_Specific(Op0)))) 5971 return ConstantFP::get(Op0->getType(), -1.0); 5972 5973 // nnan ninf X / [-]0.0 -> poison 5974 if (FMF.noInfs() && match(Op1, m_AnyZeroFP())) 5975 return PoisonValue::get(Op1->getType()); 5976 } 5977 5978 return nullptr; 5979 } 5980 5981 Value *llvm::simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5982 const SimplifyQuery &Q, 5983 fp::ExceptionBehavior ExBehavior, 5984 RoundingMode Rounding) { 5985 return ::simplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5986 Rounding); 5987 } 5988 5989 static Value * 5990 simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5991 const SimplifyQuery &Q, unsigned, 5992 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5993 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5994 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5995 if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q)) 5996 return C; 5997 5998 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5999 return C; 6000 6001 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 6002 return nullptr; 6003 6004 // Unlike fdiv, the result of frem always matches the sign of the dividend. 6005 // The constant match may include undef elements in a vector, so return a full 6006 // zero constant as the result. 6007 if (FMF.noNaNs()) { 6008 // +0 % X -> 0 6009 if (match(Op0, m_PosZeroFP())) 6010 return ConstantFP::getZero(Op0->getType()); 6011 // -0 % X -> -0 6012 if (match(Op0, m_NegZeroFP())) 6013 return ConstantFP::getNegativeZero(Op0->getType()); 6014 } 6015 6016 return nullptr; 6017 } 6018 6019 Value *llvm::simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 6020 const SimplifyQuery &Q, 6021 fp::ExceptionBehavior ExBehavior, 6022 RoundingMode Rounding) { 6023 return ::simplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 6024 Rounding); 6025 } 6026 6027 //=== Helper functions for higher up the class hierarchy. 6028 6029 /// Given the operand for a UnaryOperator, see if we can fold the result. 6030 /// If not, this returns null. 6031 static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q, 6032 unsigned MaxRecurse) { 6033 switch (Opcode) { 6034 case Instruction::FNeg: 6035 return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse); 6036 default: 6037 llvm_unreachable("Unexpected opcode"); 6038 } 6039 } 6040 6041 /// Given the operand for a UnaryOperator, see if we can fold the result. 6042 /// If not, this returns null. 6043 /// Try to use FastMathFlags when folding the result. 6044 static Value *simplifyFPUnOp(unsigned Opcode, Value *Op, 6045 const FastMathFlags &FMF, const SimplifyQuery &Q, 6046 unsigned MaxRecurse) { 6047 switch (Opcode) { 6048 case Instruction::FNeg: 6049 return simplifyFNegInst(Op, FMF, Q, MaxRecurse); 6050 default: 6051 return simplifyUnOp(Opcode, Op, Q, MaxRecurse); 6052 } 6053 } 6054 6055 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) { 6056 return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit); 6057 } 6058 6059 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 6060 const SimplifyQuery &Q) { 6061 return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit); 6062 } 6063 6064 /// Given operands for a BinaryOperator, see if we can fold the result. 6065 /// If not, this returns null. 6066 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6067 const SimplifyQuery &Q, unsigned MaxRecurse) { 6068 switch (Opcode) { 6069 case Instruction::Add: 6070 return simplifyAddInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 6071 MaxRecurse); 6072 case Instruction::Sub: 6073 return simplifySubInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 6074 MaxRecurse); 6075 case Instruction::Mul: 6076 return simplifyMulInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 6077 MaxRecurse); 6078 case Instruction::SDiv: 6079 return simplifySDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 6080 case Instruction::UDiv: 6081 return simplifyUDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 6082 case Instruction::SRem: 6083 return simplifySRemInst(LHS, RHS, Q, MaxRecurse); 6084 case Instruction::URem: 6085 return simplifyURemInst(LHS, RHS, Q, MaxRecurse); 6086 case Instruction::Shl: 6087 return simplifyShlInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 6088 MaxRecurse); 6089 case Instruction::LShr: 6090 return simplifyLShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 6091 case Instruction::AShr: 6092 return simplifyAShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 6093 case Instruction::And: 6094 return simplifyAndInst(LHS, RHS, Q, MaxRecurse); 6095 case Instruction::Or: 6096 return simplifyOrInst(LHS, RHS, Q, MaxRecurse); 6097 case Instruction::Xor: 6098 return simplifyXorInst(LHS, RHS, Q, MaxRecurse); 6099 case Instruction::FAdd: 6100 return simplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6101 case Instruction::FSub: 6102 return simplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6103 case Instruction::FMul: 6104 return simplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6105 case Instruction::FDiv: 6106 return simplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6107 case Instruction::FRem: 6108 return simplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6109 default: 6110 llvm_unreachable("Unexpected opcode"); 6111 } 6112 } 6113 6114 /// Given operands for a BinaryOperator, see if we can fold the result. 6115 /// If not, this returns null. 6116 /// Try to use FastMathFlags when folding the result. 6117 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6118 const FastMathFlags &FMF, const SimplifyQuery &Q, 6119 unsigned MaxRecurse) { 6120 switch (Opcode) { 6121 case Instruction::FAdd: 6122 return simplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse); 6123 case Instruction::FSub: 6124 return simplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse); 6125 case Instruction::FMul: 6126 return simplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse); 6127 case Instruction::FDiv: 6128 return simplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse); 6129 default: 6130 return simplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse); 6131 } 6132 } 6133 6134 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6135 const SimplifyQuery &Q) { 6136 return ::simplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit); 6137 } 6138 6139 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6140 FastMathFlags FMF, const SimplifyQuery &Q) { 6141 return ::simplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit); 6142 } 6143 6144 /// Given operands for a CmpInst, see if we can fold the result. 6145 static Value *simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 6146 const SimplifyQuery &Q, unsigned MaxRecurse) { 6147 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 6148 return simplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 6149 return simplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6150 } 6151 6152 Value *llvm::simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 6153 const SimplifyQuery &Q) { 6154 return ::simplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 6155 } 6156 6157 static bool isIdempotent(Intrinsic::ID ID) { 6158 switch (ID) { 6159 default: 6160 return false; 6161 6162 // Unary idempotent: f(f(x)) = f(x) 6163 case Intrinsic::fabs: 6164 case Intrinsic::floor: 6165 case Intrinsic::ceil: 6166 case Intrinsic::trunc: 6167 case Intrinsic::rint: 6168 case Intrinsic::nearbyint: 6169 case Intrinsic::round: 6170 case Intrinsic::roundeven: 6171 case Intrinsic::canonicalize: 6172 case Intrinsic::arithmetic_fence: 6173 return true; 6174 } 6175 } 6176 6177 /// Return true if the intrinsic rounds a floating-point value to an integral 6178 /// floating-point value (not an integer type). 6179 static bool removesFPFraction(Intrinsic::ID ID) { 6180 switch (ID) { 6181 default: 6182 return false; 6183 6184 case Intrinsic::floor: 6185 case Intrinsic::ceil: 6186 case Intrinsic::trunc: 6187 case Intrinsic::rint: 6188 case Intrinsic::nearbyint: 6189 case Intrinsic::round: 6190 case Intrinsic::roundeven: 6191 return true; 6192 } 6193 } 6194 6195 static Value *simplifyRelativeLoad(Constant *Ptr, Constant *Offset, 6196 const DataLayout &DL) { 6197 GlobalValue *PtrSym; 6198 APInt PtrOffset; 6199 if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL)) 6200 return nullptr; 6201 6202 Type *Int32Ty = Type::getInt32Ty(Ptr->getContext()); 6203 6204 auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset); 6205 if (!OffsetConstInt || OffsetConstInt->getBitWidth() > 64) 6206 return nullptr; 6207 6208 APInt OffsetInt = OffsetConstInt->getValue().sextOrTrunc( 6209 DL.getIndexTypeSizeInBits(Ptr->getType())); 6210 if (OffsetInt.srem(4) != 0) 6211 return nullptr; 6212 6213 Constant *Loaded = 6214 ConstantFoldLoadFromConstPtr(Ptr, Int32Ty, std::move(OffsetInt), DL); 6215 if (!Loaded) 6216 return nullptr; 6217 6218 auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded); 6219 if (!LoadedCE) 6220 return nullptr; 6221 6222 if (LoadedCE->getOpcode() == Instruction::Trunc) { 6223 LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 6224 if (!LoadedCE) 6225 return nullptr; 6226 } 6227 6228 if (LoadedCE->getOpcode() != Instruction::Sub) 6229 return nullptr; 6230 6231 auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 6232 if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt) 6233 return nullptr; 6234 auto *LoadedLHSPtr = LoadedLHS->getOperand(0); 6235 6236 Constant *LoadedRHS = LoadedCE->getOperand(1); 6237 GlobalValue *LoadedRHSSym; 6238 APInt LoadedRHSOffset; 6239 if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset, 6240 DL) || 6241 PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset) 6242 return nullptr; 6243 6244 return LoadedLHSPtr; 6245 } 6246 6247 // TODO: Need to pass in FastMathFlags 6248 static Value *simplifyLdexp(Value *Op0, Value *Op1, const SimplifyQuery &Q, 6249 bool IsStrict) { 6250 // ldexp(poison, x) -> poison 6251 // ldexp(x, poison) -> poison 6252 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 6253 return Op0; 6254 6255 // ldexp(undef, x) -> nan 6256 if (Q.isUndefValue(Op0)) 6257 return ConstantFP::getNaN(Op0->getType()); 6258 6259 if (!IsStrict) { 6260 // TODO: Could insert a canonicalize for strict 6261 6262 // ldexp(x, undef) -> x 6263 if (Q.isUndefValue(Op1)) 6264 return Op0; 6265 } 6266 6267 const APFloat *C = nullptr; 6268 match(Op0, PatternMatch::m_APFloat(C)); 6269 6270 // These cases should be safe, even with strictfp. 6271 // ldexp(0.0, x) -> 0.0 6272 // ldexp(-0.0, x) -> -0.0 6273 // ldexp(inf, x) -> inf 6274 // ldexp(-inf, x) -> -inf 6275 if (C && (C->isZero() || C->isInfinity())) 6276 return Op0; 6277 6278 // These are canonicalization dropping, could do it if we knew how we could 6279 // ignore denormal flushes and target handling of nan payload bits. 6280 if (IsStrict) 6281 return nullptr; 6282 6283 // TODO: Could quiet this with strictfp if the exception mode isn't strict. 6284 if (C && C->isNaN()) 6285 return ConstantFP::get(Op0->getType(), C->makeQuiet()); 6286 6287 // ldexp(x, 0) -> x 6288 6289 // TODO: Could fold this if we know the exception mode isn't 6290 // strict, we know the denormal mode and other target modes. 6291 if (match(Op1, PatternMatch::m_ZeroInt())) 6292 return Op0; 6293 6294 return nullptr; 6295 } 6296 6297 static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0, 6298 const SimplifyQuery &Q, 6299 const CallBase *Call) { 6300 // Idempotent functions return the same result when called repeatedly. 6301 Intrinsic::ID IID = F->getIntrinsicID(); 6302 if (isIdempotent(IID)) 6303 if (auto *II = dyn_cast<IntrinsicInst>(Op0)) 6304 if (II->getIntrinsicID() == IID) 6305 return II; 6306 6307 if (removesFPFraction(IID)) { 6308 // Converting from int or calling a rounding function always results in a 6309 // finite integral number or infinity. For those inputs, rounding functions 6310 // always return the same value, so the (2nd) rounding is eliminated. Ex: 6311 // floor (sitofp x) -> sitofp x 6312 // round (ceil x) -> ceil x 6313 auto *II = dyn_cast<IntrinsicInst>(Op0); 6314 if ((II && removesFPFraction(II->getIntrinsicID())) || 6315 match(Op0, m_SIToFP(m_Value())) || match(Op0, m_UIToFP(m_Value()))) 6316 return Op0; 6317 } 6318 6319 Value *X; 6320 switch (IID) { 6321 case Intrinsic::fabs: 6322 if (computeKnownFPSignBit(Op0, /*Depth=*/0, Q) == false) 6323 return Op0; 6324 break; 6325 case Intrinsic::bswap: 6326 // bswap(bswap(x)) -> x 6327 if (match(Op0, m_BSwap(m_Value(X)))) 6328 return X; 6329 break; 6330 case Intrinsic::bitreverse: 6331 // bitreverse(bitreverse(x)) -> x 6332 if (match(Op0, m_BitReverse(m_Value(X)))) 6333 return X; 6334 break; 6335 case Intrinsic::ctpop: { 6336 // ctpop(X) -> 1 iff X is non-zero power of 2. 6337 if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ false, 0, Q.AC, Q.CxtI, 6338 Q.DT)) 6339 return ConstantInt::get(Op0->getType(), 1); 6340 // If everything but the lowest bit is zero, that bit is the pop-count. Ex: 6341 // ctpop(and X, 1) --> and X, 1 6342 unsigned BitWidth = Op0->getType()->getScalarSizeInBits(); 6343 if (MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, BitWidth - 1), 6344 Q)) 6345 return Op0; 6346 break; 6347 } 6348 case Intrinsic::exp: 6349 // exp(log(x)) -> x 6350 if (Call->hasAllowReassoc() && 6351 match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X)))) 6352 return X; 6353 break; 6354 case Intrinsic::exp2: 6355 // exp2(log2(x)) -> x 6356 if (Call->hasAllowReassoc() && 6357 match(Op0, m_Intrinsic<Intrinsic::log2>(m_Value(X)))) 6358 return X; 6359 break; 6360 case Intrinsic::exp10: 6361 // exp10(log10(x)) -> x 6362 if (Call->hasAllowReassoc() && 6363 match(Op0, m_Intrinsic<Intrinsic::log10>(m_Value(X)))) 6364 return X; 6365 break; 6366 case Intrinsic::log: 6367 // log(exp(x)) -> x 6368 if (Call->hasAllowReassoc() && 6369 match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X)))) 6370 return X; 6371 break; 6372 case Intrinsic::log2: 6373 // log2(exp2(x)) -> x 6374 if (Call->hasAllowReassoc() && 6375 (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) || 6376 match(Op0, 6377 m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0), m_Value(X))))) 6378 return X; 6379 break; 6380 case Intrinsic::log10: 6381 // log10(pow(10.0, x)) -> x 6382 // log10(exp10(x)) -> x 6383 if (Call->hasAllowReassoc() && 6384 (match(Op0, m_Intrinsic<Intrinsic::exp10>(m_Value(X))) || 6385 match(Op0, 6386 m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), m_Value(X))))) 6387 return X; 6388 break; 6389 case Intrinsic::vector_reverse: 6390 // vector.reverse(vector.reverse(x)) -> x 6391 if (match(Op0, m_VecReverse(m_Value(X)))) 6392 return X; 6393 // vector.reverse(splat(X)) -> splat(X) 6394 if (isSplatValue(Op0)) 6395 return Op0; 6396 break; 6397 case Intrinsic::frexp: { 6398 // Frexp is idempotent with the added complication of the struct return. 6399 if (match(Op0, m_ExtractValue<0>(m_Value(X)))) { 6400 if (match(X, m_Intrinsic<Intrinsic::frexp>(m_Value()))) 6401 return X; 6402 } 6403 6404 break; 6405 } 6406 default: 6407 break; 6408 } 6409 6410 return nullptr; 6411 } 6412 6413 /// Given a min/max intrinsic, see if it can be removed based on having an 6414 /// operand that is another min/max intrinsic with shared operand(s). The caller 6415 /// is expected to swap the operand arguments to handle commutation. 6416 static Value *foldMinMaxSharedOp(Intrinsic::ID IID, Value *Op0, Value *Op1) { 6417 Value *X, *Y; 6418 if (!match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y)))) 6419 return nullptr; 6420 6421 auto *MM0 = dyn_cast<IntrinsicInst>(Op0); 6422 if (!MM0) 6423 return nullptr; 6424 Intrinsic::ID IID0 = MM0->getIntrinsicID(); 6425 6426 if (Op1 == X || Op1 == Y || 6427 match(Op1, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) { 6428 // max (max X, Y), X --> max X, Y 6429 if (IID0 == IID) 6430 return MM0; 6431 // max (min X, Y), X --> X 6432 if (IID0 == getInverseMinMaxIntrinsic(IID)) 6433 return Op1; 6434 } 6435 return nullptr; 6436 } 6437 6438 /// Given a min/max intrinsic, see if it can be removed based on having an 6439 /// operand that is another min/max intrinsic with shared operand(s). The caller 6440 /// is expected to swap the operand arguments to handle commutation. 6441 static Value *foldMinimumMaximumSharedOp(Intrinsic::ID IID, Value *Op0, 6442 Value *Op1) { 6443 assert((IID == Intrinsic::maxnum || IID == Intrinsic::minnum || 6444 IID == Intrinsic::maximum || IID == Intrinsic::minimum) && 6445 "Unsupported intrinsic"); 6446 6447 auto *M0 = dyn_cast<IntrinsicInst>(Op0); 6448 // If Op0 is not the same intrinsic as IID, do not process. 6449 // This is a difference with integer min/max handling. We do not process the 6450 // case like max(min(X,Y),min(X,Y)) => min(X,Y). But it can be handled by GVN. 6451 if (!M0 || M0->getIntrinsicID() != IID) 6452 return nullptr; 6453 Value *X0 = M0->getOperand(0); 6454 Value *Y0 = M0->getOperand(1); 6455 // Simple case, m(m(X,Y), X) => m(X, Y) 6456 // m(m(X,Y), Y) => m(X, Y) 6457 // For minimum/maximum, X is NaN => m(NaN, Y) == NaN and m(NaN, NaN) == NaN. 6458 // For minimum/maximum, Y is NaN => m(X, NaN) == NaN and m(NaN, NaN) == NaN. 6459 // For minnum/maxnum, X is NaN => m(NaN, Y) == Y and m(Y, Y) == Y. 6460 // For minnum/maxnum, Y is NaN => m(X, NaN) == X and m(X, NaN) == X. 6461 if (X0 == Op1 || Y0 == Op1) 6462 return M0; 6463 6464 auto *M1 = dyn_cast<IntrinsicInst>(Op1); 6465 if (!M1) 6466 return nullptr; 6467 Value *X1 = M1->getOperand(0); 6468 Value *Y1 = M1->getOperand(1); 6469 Intrinsic::ID IID1 = M1->getIntrinsicID(); 6470 // we have a case m(m(X,Y),m'(X,Y)) taking into account m' is commutative. 6471 // if m' is m or inversion of m => m(m(X,Y),m'(X,Y)) == m(X,Y). 6472 // For minimum/maximum, X is NaN => m(NaN,Y) == m'(NaN, Y) == NaN. 6473 // For minimum/maximum, Y is NaN => m(X,NaN) == m'(X, NaN) == NaN. 6474 // For minnum/maxnum, X is NaN => m(NaN,Y) == m'(NaN, Y) == Y. 6475 // For minnum/maxnum, Y is NaN => m(X,NaN) == m'(X, NaN) == X. 6476 if ((X0 == X1 && Y0 == Y1) || (X0 == Y1 && Y0 == X1)) 6477 if (IID1 == IID || getInverseMinMaxIntrinsic(IID1) == IID) 6478 return M0; 6479 6480 return nullptr; 6481 } 6482 6483 Value *llvm::simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType, 6484 Value *Op0, Value *Op1, 6485 const SimplifyQuery &Q, 6486 const CallBase *Call) { 6487 unsigned BitWidth = ReturnType->getScalarSizeInBits(); 6488 switch (IID) { 6489 case Intrinsic::abs: 6490 // abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here. 6491 // It is always ok to pick the earlier abs. We'll just lose nsw if its only 6492 // on the outer abs. 6493 if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(), m_Value()))) 6494 return Op0; 6495 break; 6496 6497 case Intrinsic::cttz: { 6498 Value *X; 6499 if (match(Op0, m_Shl(m_One(), m_Value(X)))) 6500 return X; 6501 break; 6502 } 6503 case Intrinsic::ctlz: { 6504 Value *X; 6505 if (match(Op0, m_LShr(m_Negative(), m_Value(X)))) 6506 return X; 6507 if (match(Op0, m_AShr(m_Negative(), m_Value()))) 6508 return Constant::getNullValue(ReturnType); 6509 break; 6510 } 6511 case Intrinsic::ptrmask: { 6512 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 6513 return PoisonValue::get(Op0->getType()); 6514 6515 // NOTE: We can't apply this simplifications based on the value of Op1 6516 // because we need to preserve provenance. 6517 if (Q.isUndefValue(Op0) || match(Op0, m_Zero())) 6518 return Constant::getNullValue(Op0->getType()); 6519 6520 assert(Op1->getType()->getScalarSizeInBits() == 6521 Q.DL.getIndexTypeSizeInBits(Op0->getType()) && 6522 "Invalid mask width"); 6523 // If index-width (mask size) is less than pointer-size then mask is 6524 // 1-extended. 6525 if (match(Op1, m_PtrToInt(m_Specific(Op0)))) 6526 return Op0; 6527 6528 // NOTE: We may have attributes associated with the return value of the 6529 // llvm.ptrmask intrinsic that will be lost when we just return the 6530 // operand. We should try to preserve them. 6531 if (match(Op1, m_AllOnes()) || Q.isUndefValue(Op1)) 6532 return Op0; 6533 6534 Constant *C; 6535 if (match(Op1, m_ImmConstant(C))) { 6536 KnownBits PtrKnown = computeKnownBits(Op0, /*Depth=*/0, Q); 6537 // See if we only masking off bits we know are already zero due to 6538 // alignment. 6539 APInt IrrelevantPtrBits = 6540 PtrKnown.Zero.zextOrTrunc(C->getType()->getScalarSizeInBits()); 6541 C = ConstantFoldBinaryOpOperands( 6542 Instruction::Or, C, ConstantInt::get(C->getType(), IrrelevantPtrBits), 6543 Q.DL); 6544 if (C != nullptr && C->isAllOnesValue()) 6545 return Op0; 6546 } 6547 break; 6548 } 6549 case Intrinsic::smax: 6550 case Intrinsic::smin: 6551 case Intrinsic::umax: 6552 case Intrinsic::umin: { 6553 // If the arguments are the same, this is a no-op. 6554 if (Op0 == Op1) 6555 return Op0; 6556 6557 // Canonicalize immediate constant operand as Op1. 6558 if (match(Op0, m_ImmConstant())) 6559 std::swap(Op0, Op1); 6560 6561 // Assume undef is the limit value. 6562 if (Q.isUndefValue(Op1)) 6563 return ConstantInt::get( 6564 ReturnType, MinMaxIntrinsic::getSaturationPoint(IID, BitWidth)); 6565 6566 const APInt *C; 6567 if (match(Op1, m_APIntAllowPoison(C))) { 6568 // Clamp to limit value. For example: 6569 // umax(i8 %x, i8 255) --> 255 6570 if (*C == MinMaxIntrinsic::getSaturationPoint(IID, BitWidth)) 6571 return ConstantInt::get(ReturnType, *C); 6572 6573 // If the constant op is the opposite of the limit value, the other must 6574 // be larger/smaller or equal. For example: 6575 // umin(i8 %x, i8 255) --> %x 6576 if (*C == MinMaxIntrinsic::getSaturationPoint( 6577 getInverseMinMaxIntrinsic(IID), BitWidth)) 6578 return Op0; 6579 6580 // Remove nested call if constant operands allow it. Example: 6581 // max (max X, 7), 5 -> max X, 7 6582 auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0); 6583 if (MinMax0 && MinMax0->getIntrinsicID() == IID) { 6584 // TODO: loosen undef/splat restrictions for vector constants. 6585 Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1); 6586 const APInt *InnerC; 6587 if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) && 6588 ICmpInst::compare(*InnerC, *C, 6589 ICmpInst::getNonStrictPredicate( 6590 MinMaxIntrinsic::getPredicate(IID)))) 6591 return Op0; 6592 } 6593 } 6594 6595 if (Value *V = foldMinMaxSharedOp(IID, Op0, Op1)) 6596 return V; 6597 if (Value *V = foldMinMaxSharedOp(IID, Op1, Op0)) 6598 return V; 6599 6600 ICmpInst::Predicate Pred = 6601 ICmpInst::getNonStrictPredicate(MinMaxIntrinsic::getPredicate(IID)); 6602 if (isICmpTrue(Pred, Op0, Op1, Q.getWithoutUndef(), RecursionLimit)) 6603 return Op0; 6604 if (isICmpTrue(Pred, Op1, Op0, Q.getWithoutUndef(), RecursionLimit)) 6605 return Op1; 6606 6607 break; 6608 } 6609 case Intrinsic::scmp: 6610 case Intrinsic::ucmp: { 6611 // Fold to a constant if the relationship between operands can be 6612 // established with certainty 6613 if (isICmpTrue(CmpInst::ICMP_EQ, Op0, Op1, Q, RecursionLimit)) 6614 return Constant::getNullValue(ReturnType); 6615 6616 ICmpInst::Predicate PredGT = 6617 IID == Intrinsic::scmp ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 6618 if (isICmpTrue(PredGT, Op0, Op1, Q, RecursionLimit)) 6619 return ConstantInt::get(ReturnType, 1); 6620 6621 ICmpInst::Predicate PredLT = 6622 IID == Intrinsic::scmp ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 6623 if (isICmpTrue(PredLT, Op0, Op1, Q, RecursionLimit)) 6624 return ConstantInt::getSigned(ReturnType, -1); 6625 6626 break; 6627 } 6628 case Intrinsic::usub_with_overflow: 6629 case Intrinsic::ssub_with_overflow: 6630 // X - X -> { 0, false } 6631 // X - undef -> { 0, false } 6632 // undef - X -> { 0, false } 6633 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6634 return Constant::getNullValue(ReturnType); 6635 break; 6636 case Intrinsic::uadd_with_overflow: 6637 case Intrinsic::sadd_with_overflow: 6638 // X + undef -> { -1, false } 6639 // undef + x -> { -1, false } 6640 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) { 6641 return ConstantStruct::get( 6642 cast<StructType>(ReturnType), 6643 {Constant::getAllOnesValue(ReturnType->getStructElementType(0)), 6644 Constant::getNullValue(ReturnType->getStructElementType(1))}); 6645 } 6646 break; 6647 case Intrinsic::umul_with_overflow: 6648 case Intrinsic::smul_with_overflow: 6649 // 0 * X -> { 0, false } 6650 // X * 0 -> { 0, false } 6651 if (match(Op0, m_Zero()) || match(Op1, m_Zero())) 6652 return Constant::getNullValue(ReturnType); 6653 // undef * X -> { 0, false } 6654 // X * undef -> { 0, false } 6655 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6656 return Constant::getNullValue(ReturnType); 6657 break; 6658 case Intrinsic::uadd_sat: 6659 // sat(MAX + X) -> MAX 6660 // sat(X + MAX) -> MAX 6661 if (match(Op0, m_AllOnes()) || match(Op1, m_AllOnes())) 6662 return Constant::getAllOnesValue(ReturnType); 6663 [[fallthrough]]; 6664 case Intrinsic::sadd_sat: 6665 // sat(X + undef) -> -1 6666 // sat(undef + X) -> -1 6667 // For unsigned: Assume undef is MAX, thus we saturate to MAX (-1). 6668 // For signed: Assume undef is ~X, in which case X + ~X = -1. 6669 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6670 return Constant::getAllOnesValue(ReturnType); 6671 6672 // X + 0 -> X 6673 if (match(Op1, m_Zero())) 6674 return Op0; 6675 // 0 + X -> X 6676 if (match(Op0, m_Zero())) 6677 return Op1; 6678 break; 6679 case Intrinsic::usub_sat: 6680 // sat(0 - X) -> 0, sat(X - MAX) -> 0 6681 if (match(Op0, m_Zero()) || match(Op1, m_AllOnes())) 6682 return Constant::getNullValue(ReturnType); 6683 [[fallthrough]]; 6684 case Intrinsic::ssub_sat: 6685 // X - X -> 0, X - undef -> 0, undef - X -> 0 6686 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6687 return Constant::getNullValue(ReturnType); 6688 // X - 0 -> X 6689 if (match(Op1, m_Zero())) 6690 return Op0; 6691 break; 6692 case Intrinsic::load_relative: 6693 if (auto *C0 = dyn_cast<Constant>(Op0)) 6694 if (auto *C1 = dyn_cast<Constant>(Op1)) 6695 return simplifyRelativeLoad(C0, C1, Q.DL); 6696 break; 6697 case Intrinsic::powi: 6698 if (auto *Power = dyn_cast<ConstantInt>(Op1)) { 6699 // powi(x, 0) -> 1.0 6700 if (Power->isZero()) 6701 return ConstantFP::get(Op0->getType(), 1.0); 6702 // powi(x, 1) -> x 6703 if (Power->isOne()) 6704 return Op0; 6705 } 6706 break; 6707 case Intrinsic::ldexp: 6708 return simplifyLdexp(Op0, Op1, Q, false); 6709 case Intrinsic::copysign: 6710 // copysign X, X --> X 6711 if (Op0 == Op1) 6712 return Op0; 6713 // copysign -X, X --> X 6714 // copysign X, -X --> -X 6715 if (match(Op0, m_FNeg(m_Specific(Op1))) || 6716 match(Op1, m_FNeg(m_Specific(Op0)))) 6717 return Op1; 6718 break; 6719 case Intrinsic::is_fpclass: { 6720 if (isa<PoisonValue>(Op0)) 6721 return PoisonValue::get(ReturnType); 6722 6723 uint64_t Mask = cast<ConstantInt>(Op1)->getZExtValue(); 6724 // If all tests are made, it doesn't matter what the value is. 6725 if ((Mask & fcAllFlags) == fcAllFlags) 6726 return ConstantInt::get(ReturnType, true); 6727 if ((Mask & fcAllFlags) == 0) 6728 return ConstantInt::get(ReturnType, false); 6729 if (Q.isUndefValue(Op0)) 6730 return UndefValue::get(ReturnType); 6731 break; 6732 } 6733 case Intrinsic::maxnum: 6734 case Intrinsic::minnum: 6735 case Intrinsic::maximum: 6736 case Intrinsic::minimum: { 6737 // If the arguments are the same, this is a no-op. 6738 if (Op0 == Op1) 6739 return Op0; 6740 6741 // Canonicalize constant operand as Op1. 6742 if (isa<Constant>(Op0)) 6743 std::swap(Op0, Op1); 6744 6745 // If an argument is undef, return the other argument. 6746 if (Q.isUndefValue(Op1)) 6747 return Op0; 6748 6749 bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum; 6750 bool IsMin = IID == Intrinsic::minimum || IID == Intrinsic::minnum; 6751 6752 // minnum(X, nan) -> X 6753 // maxnum(X, nan) -> X 6754 // minimum(X, nan) -> nan 6755 // maximum(X, nan) -> nan 6756 if (match(Op1, m_NaN())) 6757 return PropagateNaN ? propagateNaN(cast<Constant>(Op1)) : Op0; 6758 6759 // In the following folds, inf can be replaced with the largest finite 6760 // float, if the ninf flag is set. 6761 const APFloat *C; 6762 if (match(Op1, m_APFloat(C)) && 6763 (C->isInfinity() || (Call && Call->hasNoInfs() && C->isLargest()))) { 6764 // minnum(X, -inf) -> -inf 6765 // maxnum(X, +inf) -> +inf 6766 // minimum(X, -inf) -> -inf if nnan 6767 // maximum(X, +inf) -> +inf if nnan 6768 if (C->isNegative() == IsMin && 6769 (!PropagateNaN || (Call && Call->hasNoNaNs()))) 6770 return ConstantFP::get(ReturnType, *C); 6771 6772 // minnum(X, +inf) -> X if nnan 6773 // maxnum(X, -inf) -> X if nnan 6774 // minimum(X, +inf) -> X 6775 // maximum(X, -inf) -> X 6776 if (C->isNegative() != IsMin && 6777 (PropagateNaN || (Call && Call->hasNoNaNs()))) 6778 return Op0; 6779 } 6780 6781 // Min/max of the same operation with common operand: 6782 // m(m(X, Y)), X --> m(X, Y) (4 commuted variants) 6783 if (Value *V = foldMinimumMaximumSharedOp(IID, Op0, Op1)) 6784 return V; 6785 if (Value *V = foldMinimumMaximumSharedOp(IID, Op1, Op0)) 6786 return V; 6787 6788 break; 6789 } 6790 case Intrinsic::vector_extract: { 6791 // (extract_vector (insert_vector _, X, 0), 0) -> X 6792 unsigned IdxN = cast<ConstantInt>(Op1)->getZExtValue(); 6793 Value *X = nullptr; 6794 if (match(Op0, m_Intrinsic<Intrinsic::vector_insert>(m_Value(), m_Value(X), 6795 m_Zero())) && 6796 IdxN == 0 && X->getType() == ReturnType) 6797 return X; 6798 6799 break; 6800 } 6801 default: 6802 break; 6803 } 6804 6805 return nullptr; 6806 } 6807 6808 static Value *simplifyIntrinsic(CallBase *Call, Value *Callee, 6809 ArrayRef<Value *> Args, 6810 const SimplifyQuery &Q) { 6811 // Operand bundles should not be in Args. 6812 assert(Call->arg_size() == Args.size()); 6813 unsigned NumOperands = Args.size(); 6814 Function *F = cast<Function>(Callee); 6815 Intrinsic::ID IID = F->getIntrinsicID(); 6816 6817 // Most of the intrinsics with no operands have some kind of side effect. 6818 // Don't simplify. 6819 if (!NumOperands) { 6820 switch (IID) { 6821 case Intrinsic::vscale: { 6822 Type *RetTy = F->getReturnType(); 6823 ConstantRange CR = getVScaleRange(Call->getFunction(), 64); 6824 if (const APInt *C = CR.getSingleElement()) 6825 return ConstantInt::get(RetTy, C->getZExtValue()); 6826 return nullptr; 6827 } 6828 default: 6829 return nullptr; 6830 } 6831 } 6832 6833 if (NumOperands == 1) 6834 return simplifyUnaryIntrinsic(F, Args[0], Q, Call); 6835 6836 if (NumOperands == 2) 6837 return simplifyBinaryIntrinsic(IID, F->getReturnType(), Args[0], Args[1], Q, 6838 Call); 6839 6840 // Handle intrinsics with 3 or more arguments. 6841 switch (IID) { 6842 case Intrinsic::masked_load: 6843 case Intrinsic::masked_gather: { 6844 Value *MaskArg = Args[2]; 6845 Value *PassthruArg = Args[3]; 6846 // If the mask is all zeros or undef, the "passthru" argument is the result. 6847 if (maskIsAllZeroOrUndef(MaskArg)) 6848 return PassthruArg; 6849 return nullptr; 6850 } 6851 case Intrinsic::fshl: 6852 case Intrinsic::fshr: { 6853 Value *Op0 = Args[0], *Op1 = Args[1], *ShAmtArg = Args[2]; 6854 6855 // If both operands are undef, the result is undef. 6856 if (Q.isUndefValue(Op0) && Q.isUndefValue(Op1)) 6857 return UndefValue::get(F->getReturnType()); 6858 6859 // If shift amount is undef, assume it is zero. 6860 if (Q.isUndefValue(ShAmtArg)) 6861 return Args[IID == Intrinsic::fshl ? 0 : 1]; 6862 6863 const APInt *ShAmtC; 6864 if (match(ShAmtArg, m_APInt(ShAmtC))) { 6865 // If there's effectively no shift, return the 1st arg or 2nd arg. 6866 APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth()); 6867 if (ShAmtC->urem(BitWidth).isZero()) 6868 return Args[IID == Intrinsic::fshl ? 0 : 1]; 6869 } 6870 6871 // Rotating zero by anything is zero. 6872 if (match(Op0, m_Zero()) && match(Op1, m_Zero())) 6873 return ConstantInt::getNullValue(F->getReturnType()); 6874 6875 // Rotating -1 by anything is -1. 6876 if (match(Op0, m_AllOnes()) && match(Op1, m_AllOnes())) 6877 return ConstantInt::getAllOnesValue(F->getReturnType()); 6878 6879 return nullptr; 6880 } 6881 case Intrinsic::experimental_constrained_fma: { 6882 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6883 if (Value *V = simplifyFPOp(Args, {}, Q, *FPI->getExceptionBehavior(), 6884 *FPI->getRoundingMode())) 6885 return V; 6886 return nullptr; 6887 } 6888 case Intrinsic::fma: 6889 case Intrinsic::fmuladd: { 6890 if (Value *V = simplifyFPOp(Args, {}, Q, fp::ebIgnore, 6891 RoundingMode::NearestTiesToEven)) 6892 return V; 6893 return nullptr; 6894 } 6895 case Intrinsic::smul_fix: 6896 case Intrinsic::smul_fix_sat: { 6897 Value *Op0 = Args[0]; 6898 Value *Op1 = Args[1]; 6899 Value *Op2 = Args[2]; 6900 Type *ReturnType = F->getReturnType(); 6901 6902 // Canonicalize constant operand as Op1 (ConstantFolding handles the case 6903 // when both Op0 and Op1 are constant so we do not care about that special 6904 // case here). 6905 if (isa<Constant>(Op0)) 6906 std::swap(Op0, Op1); 6907 6908 // X * 0 -> 0 6909 if (match(Op1, m_Zero())) 6910 return Constant::getNullValue(ReturnType); 6911 6912 // X * undef -> 0 6913 if (Q.isUndefValue(Op1)) 6914 return Constant::getNullValue(ReturnType); 6915 6916 // X * (1 << Scale) -> X 6917 APInt ScaledOne = 6918 APInt::getOneBitSet(ReturnType->getScalarSizeInBits(), 6919 cast<ConstantInt>(Op2)->getZExtValue()); 6920 if (ScaledOne.isNonNegative() && match(Op1, m_SpecificInt(ScaledOne))) 6921 return Op0; 6922 6923 return nullptr; 6924 } 6925 case Intrinsic::vector_insert: { 6926 Value *Vec = Args[0]; 6927 Value *SubVec = Args[1]; 6928 Value *Idx = Args[2]; 6929 Type *ReturnType = F->getReturnType(); 6930 6931 // (insert_vector Y, (extract_vector X, 0), 0) -> X 6932 // where: Y is X, or Y is undef 6933 unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue(); 6934 Value *X = nullptr; 6935 if (match(SubVec, 6936 m_Intrinsic<Intrinsic::vector_extract>(m_Value(X), m_Zero())) && 6937 (Q.isUndefValue(Vec) || Vec == X) && IdxN == 0 && 6938 X->getType() == ReturnType) 6939 return X; 6940 6941 return nullptr; 6942 } 6943 case Intrinsic::experimental_constrained_fadd: { 6944 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6945 return simplifyFAddInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6946 *FPI->getExceptionBehavior(), 6947 *FPI->getRoundingMode()); 6948 } 6949 case Intrinsic::experimental_constrained_fsub: { 6950 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6951 return simplifyFSubInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6952 *FPI->getExceptionBehavior(), 6953 *FPI->getRoundingMode()); 6954 } 6955 case Intrinsic::experimental_constrained_fmul: { 6956 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6957 return simplifyFMulInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6958 *FPI->getExceptionBehavior(), 6959 *FPI->getRoundingMode()); 6960 } 6961 case Intrinsic::experimental_constrained_fdiv: { 6962 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6963 return simplifyFDivInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6964 *FPI->getExceptionBehavior(), 6965 *FPI->getRoundingMode()); 6966 } 6967 case Intrinsic::experimental_constrained_frem: { 6968 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6969 return simplifyFRemInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6970 *FPI->getExceptionBehavior(), 6971 *FPI->getRoundingMode()); 6972 } 6973 case Intrinsic::experimental_constrained_ldexp: 6974 return simplifyLdexp(Args[0], Args[1], Q, true); 6975 case Intrinsic::experimental_gc_relocate: { 6976 GCRelocateInst &GCR = *cast<GCRelocateInst>(Call); 6977 Value *DerivedPtr = GCR.getDerivedPtr(); 6978 Value *BasePtr = GCR.getBasePtr(); 6979 6980 // Undef is undef, even after relocation. 6981 if (isa<UndefValue>(DerivedPtr) || isa<UndefValue>(BasePtr)) { 6982 return UndefValue::get(GCR.getType()); 6983 } 6984 6985 if (auto *PT = dyn_cast<PointerType>(GCR.getType())) { 6986 // For now, the assumption is that the relocation of null will be null 6987 // for most any collector. If this ever changes, a corresponding hook 6988 // should be added to GCStrategy and this code should check it first. 6989 if (isa<ConstantPointerNull>(DerivedPtr)) { 6990 // Use null-pointer of gc_relocate's type to replace it. 6991 return ConstantPointerNull::get(PT); 6992 } 6993 } 6994 return nullptr; 6995 } 6996 default: 6997 return nullptr; 6998 } 6999 } 7000 7001 static Value *tryConstantFoldCall(CallBase *Call, Value *Callee, 7002 ArrayRef<Value *> Args, 7003 const SimplifyQuery &Q) { 7004 auto *F = dyn_cast<Function>(Callee); 7005 if (!F || !canConstantFoldCallTo(Call, F)) 7006 return nullptr; 7007 7008 SmallVector<Constant *, 4> ConstantArgs; 7009 ConstantArgs.reserve(Args.size()); 7010 for (Value *Arg : Args) { 7011 Constant *C = dyn_cast<Constant>(Arg); 7012 if (!C) { 7013 if (isa<MetadataAsValue>(Arg)) 7014 continue; 7015 return nullptr; 7016 } 7017 ConstantArgs.push_back(C); 7018 } 7019 7020 return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI); 7021 } 7022 7023 Value *llvm::simplifyCall(CallBase *Call, Value *Callee, ArrayRef<Value *> Args, 7024 const SimplifyQuery &Q) { 7025 // Args should not contain operand bundle operands. 7026 assert(Call->arg_size() == Args.size()); 7027 7028 // musttail calls can only be simplified if they are also DCEd. 7029 // As we can't guarantee this here, don't simplify them. 7030 if (Call->isMustTailCall()) 7031 return nullptr; 7032 7033 // call undef -> poison 7034 // call null -> poison 7035 if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee)) 7036 return PoisonValue::get(Call->getType()); 7037 7038 if (Value *V = tryConstantFoldCall(Call, Callee, Args, Q)) 7039 return V; 7040 7041 auto *F = dyn_cast<Function>(Callee); 7042 if (F && F->isIntrinsic()) 7043 if (Value *Ret = simplifyIntrinsic(Call, Callee, Args, Q)) 7044 return Ret; 7045 7046 return nullptr; 7047 } 7048 7049 Value *llvm::simplifyConstrainedFPCall(CallBase *Call, const SimplifyQuery &Q) { 7050 assert(isa<ConstrainedFPIntrinsic>(Call)); 7051 SmallVector<Value *, 4> Args(Call->args()); 7052 if (Value *V = tryConstantFoldCall(Call, Call->getCalledOperand(), Args, Q)) 7053 return V; 7054 if (Value *Ret = simplifyIntrinsic(Call, Call->getCalledOperand(), Args, Q)) 7055 return Ret; 7056 return nullptr; 7057 } 7058 7059 /// Given operands for a Freeze, see if we can fold the result. 7060 static Value *simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 7061 // Use a utility function defined in ValueTracking. 7062 if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT)) 7063 return Op0; 7064 // We have room for improvement. 7065 return nullptr; 7066 } 7067 7068 Value *llvm::simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 7069 return ::simplifyFreezeInst(Op0, Q); 7070 } 7071 7072 Value *llvm::simplifyLoadInst(LoadInst *LI, Value *PtrOp, 7073 const SimplifyQuery &Q) { 7074 if (LI->isVolatile()) 7075 return nullptr; 7076 7077 if (auto *PtrOpC = dyn_cast<Constant>(PtrOp)) 7078 return ConstantFoldLoadFromConstPtr(PtrOpC, LI->getType(), Q.DL); 7079 7080 // We can only fold the load if it is from a constant global with definitive 7081 // initializer. Skip expensive logic if this is not the case. 7082 auto *GV = dyn_cast<GlobalVariable>(getUnderlyingObject(PtrOp)); 7083 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) 7084 return nullptr; 7085 7086 // If GlobalVariable's initializer is uniform, then return the constant 7087 // regardless of its offset. 7088 if (Constant *C = ConstantFoldLoadFromUniformValue(GV->getInitializer(), 7089 LI->getType(), Q.DL)) 7090 return C; 7091 7092 // Try to convert operand into a constant by stripping offsets while looking 7093 // through invariant.group intrinsics. 7094 APInt Offset(Q.DL.getIndexTypeSizeInBits(PtrOp->getType()), 0); 7095 PtrOp = PtrOp->stripAndAccumulateConstantOffsets( 7096 Q.DL, Offset, /* AllowNonInbounts */ true, 7097 /* AllowInvariantGroup */ true); 7098 if (PtrOp == GV) { 7099 // Index size may have changed due to address space casts. 7100 Offset = Offset.sextOrTrunc(Q.DL.getIndexTypeSizeInBits(PtrOp->getType())); 7101 return ConstantFoldLoadFromConstPtr(GV, LI->getType(), std::move(Offset), 7102 Q.DL); 7103 } 7104 7105 return nullptr; 7106 } 7107 7108 /// See if we can compute a simplified version of this instruction. 7109 /// If not, this returns null. 7110 7111 static Value *simplifyInstructionWithOperands(Instruction *I, 7112 ArrayRef<Value *> NewOps, 7113 const SimplifyQuery &SQ, 7114 unsigned MaxRecurse) { 7115 assert(I->getFunction() && "instruction should be inserted in a function"); 7116 assert((!SQ.CxtI || SQ.CxtI->getFunction() == I->getFunction()) && 7117 "context instruction should be in the same function"); 7118 7119 const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I); 7120 7121 switch (I->getOpcode()) { 7122 default: 7123 if (llvm::all_of(NewOps, [](Value *V) { return isa<Constant>(V); })) { 7124 SmallVector<Constant *, 8> NewConstOps(NewOps.size()); 7125 transform(NewOps, NewConstOps.begin(), 7126 [](Value *V) { return cast<Constant>(V); }); 7127 return ConstantFoldInstOperands(I, NewConstOps, Q.DL, Q.TLI); 7128 } 7129 return nullptr; 7130 case Instruction::FNeg: 7131 return simplifyFNegInst(NewOps[0], I->getFastMathFlags(), Q, MaxRecurse); 7132 case Instruction::FAdd: 7133 return simplifyFAddInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7134 MaxRecurse); 7135 case Instruction::Add: 7136 return simplifyAddInst( 7137 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7138 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7139 case Instruction::FSub: 7140 return simplifyFSubInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7141 MaxRecurse); 7142 case Instruction::Sub: 7143 return simplifySubInst( 7144 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7145 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7146 case Instruction::FMul: 7147 return simplifyFMulInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7148 MaxRecurse); 7149 case Instruction::Mul: 7150 return simplifyMulInst( 7151 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7152 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7153 case Instruction::SDiv: 7154 return simplifySDivInst(NewOps[0], NewOps[1], 7155 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7156 MaxRecurse); 7157 case Instruction::UDiv: 7158 return simplifyUDivInst(NewOps[0], NewOps[1], 7159 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7160 MaxRecurse); 7161 case Instruction::FDiv: 7162 return simplifyFDivInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7163 MaxRecurse); 7164 case Instruction::SRem: 7165 return simplifySRemInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7166 case Instruction::URem: 7167 return simplifyURemInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7168 case Instruction::FRem: 7169 return simplifyFRemInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7170 MaxRecurse); 7171 case Instruction::Shl: 7172 return simplifyShlInst( 7173 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7174 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7175 case Instruction::LShr: 7176 return simplifyLShrInst(NewOps[0], NewOps[1], 7177 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7178 MaxRecurse); 7179 case Instruction::AShr: 7180 return simplifyAShrInst(NewOps[0], NewOps[1], 7181 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7182 MaxRecurse); 7183 case Instruction::And: 7184 return simplifyAndInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7185 case Instruction::Or: 7186 return simplifyOrInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7187 case Instruction::Xor: 7188 return simplifyXorInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7189 case Instruction::ICmp: 7190 return simplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), NewOps[0], 7191 NewOps[1], Q, MaxRecurse); 7192 case Instruction::FCmp: 7193 return simplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), NewOps[0], 7194 NewOps[1], I->getFastMathFlags(), Q, MaxRecurse); 7195 case Instruction::Select: 7196 return simplifySelectInst(NewOps[0], NewOps[1], NewOps[2], Q, MaxRecurse); 7197 break; 7198 case Instruction::GetElementPtr: { 7199 auto *GEPI = cast<GetElementPtrInst>(I); 7200 return simplifyGEPInst(GEPI->getSourceElementType(), NewOps[0], 7201 ArrayRef(NewOps).slice(1), GEPI->getNoWrapFlags(), Q, 7202 MaxRecurse); 7203 } 7204 case Instruction::InsertValue: { 7205 InsertValueInst *IV = cast<InsertValueInst>(I); 7206 return simplifyInsertValueInst(NewOps[0], NewOps[1], IV->getIndices(), Q, 7207 MaxRecurse); 7208 } 7209 case Instruction::InsertElement: 7210 return simplifyInsertElementInst(NewOps[0], NewOps[1], NewOps[2], Q); 7211 case Instruction::ExtractValue: { 7212 auto *EVI = cast<ExtractValueInst>(I); 7213 return simplifyExtractValueInst(NewOps[0], EVI->getIndices(), Q, 7214 MaxRecurse); 7215 } 7216 case Instruction::ExtractElement: 7217 return simplifyExtractElementInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7218 case Instruction::ShuffleVector: { 7219 auto *SVI = cast<ShuffleVectorInst>(I); 7220 return simplifyShuffleVectorInst(NewOps[0], NewOps[1], 7221 SVI->getShuffleMask(), SVI->getType(), Q, 7222 MaxRecurse); 7223 } 7224 case Instruction::PHI: 7225 return simplifyPHINode(cast<PHINode>(I), NewOps, Q); 7226 case Instruction::Call: 7227 return simplifyCall( 7228 cast<CallInst>(I), NewOps.back(), 7229 NewOps.drop_back(1 + cast<CallInst>(I)->getNumTotalBundleOperands()), Q); 7230 case Instruction::Freeze: 7231 return llvm::simplifyFreezeInst(NewOps[0], Q); 7232 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc: 7233 #include "llvm/IR/Instruction.def" 7234 #undef HANDLE_CAST_INST 7235 return simplifyCastInst(I->getOpcode(), NewOps[0], I->getType(), Q, 7236 MaxRecurse); 7237 case Instruction::Alloca: 7238 // No simplifications for Alloca and it can't be constant folded. 7239 return nullptr; 7240 case Instruction::Load: 7241 return simplifyLoadInst(cast<LoadInst>(I), NewOps[0], Q); 7242 } 7243 } 7244 7245 Value *llvm::simplifyInstructionWithOperands(Instruction *I, 7246 ArrayRef<Value *> NewOps, 7247 const SimplifyQuery &SQ) { 7248 assert(NewOps.size() == I->getNumOperands() && 7249 "Number of operands should match the instruction!"); 7250 return ::simplifyInstructionWithOperands(I, NewOps, SQ, RecursionLimit); 7251 } 7252 7253 Value *llvm::simplifyInstruction(Instruction *I, const SimplifyQuery &SQ) { 7254 SmallVector<Value *, 8> Ops(I->operands()); 7255 Value *Result = ::simplifyInstructionWithOperands(I, Ops, SQ, RecursionLimit); 7256 7257 /// If called on unreachable code, the instruction may simplify to itself. 7258 /// Make life easier for users by detecting that case here, and returning a 7259 /// safe value instead. 7260 return Result == I ? PoisonValue::get(I->getType()) : Result; 7261 } 7262 7263 /// Implementation of recursive simplification through an instruction's 7264 /// uses. 7265 /// 7266 /// This is the common implementation of the recursive simplification routines. 7267 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to 7268 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of 7269 /// instructions to process and attempt to simplify it using 7270 /// InstructionSimplify. Recursively visited users which could not be 7271 /// simplified themselves are to the optional UnsimplifiedUsers set for 7272 /// further processing by the caller. 7273 /// 7274 /// This routine returns 'true' only when *it* simplifies something. The passed 7275 /// in simplified value does not count toward this. 7276 static bool replaceAndRecursivelySimplifyImpl( 7277 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 7278 const DominatorTree *DT, AssumptionCache *AC, 7279 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) { 7280 bool Simplified = false; 7281 SmallSetVector<Instruction *, 8> Worklist; 7282 const DataLayout &DL = I->getDataLayout(); 7283 7284 // If we have an explicit value to collapse to, do that round of the 7285 // simplification loop by hand initially. 7286 if (SimpleV) { 7287 for (User *U : I->users()) 7288 if (U != I) 7289 Worklist.insert(cast<Instruction>(U)); 7290 7291 // Replace the instruction with its simplified value. 7292 I->replaceAllUsesWith(SimpleV); 7293 7294 if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects()) 7295 I->eraseFromParent(); 7296 } else { 7297 Worklist.insert(I); 7298 } 7299 7300 // Note that we must test the size on each iteration, the worklist can grow. 7301 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { 7302 I = Worklist[Idx]; 7303 7304 // See if this instruction simplifies. 7305 SimpleV = simplifyInstruction(I, {DL, TLI, DT, AC}); 7306 if (!SimpleV) { 7307 if (UnsimplifiedUsers) 7308 UnsimplifiedUsers->insert(I); 7309 continue; 7310 } 7311 7312 Simplified = true; 7313 7314 // Stash away all the uses of the old instruction so we can check them for 7315 // recursive simplifications after a RAUW. This is cheaper than checking all 7316 // uses of To on the recursive step in most cases. 7317 for (User *U : I->users()) 7318 Worklist.insert(cast<Instruction>(U)); 7319 7320 // Replace the instruction with its simplified value. 7321 I->replaceAllUsesWith(SimpleV); 7322 7323 if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects()) 7324 I->eraseFromParent(); 7325 } 7326 return Simplified; 7327 } 7328 7329 bool llvm::replaceAndRecursivelySimplify( 7330 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 7331 const DominatorTree *DT, AssumptionCache *AC, 7332 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) { 7333 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!"); 7334 assert(SimpleV && "Must provide a simplified value."); 7335 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC, 7336 UnsimplifiedUsers); 7337 } 7338 7339 namespace llvm { 7340 const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) { 7341 auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>(); 7342 auto *DT = DTWP ? &DTWP->getDomTree() : nullptr; 7343 auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>(); 7344 auto *TLI = TLIWP ? &TLIWP->getTLI(F) : nullptr; 7345 auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>(); 7346 auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr; 7347 return {F.getDataLayout(), TLI, DT, AC}; 7348 } 7349 7350 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR, 7351 const DataLayout &DL) { 7352 return {DL, &AR.TLI, &AR.DT, &AR.AC}; 7353 } 7354 7355 template <class T, class... TArgs> 7356 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM, 7357 Function &F) { 7358 auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F); 7359 auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F); 7360 auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F); 7361 return {F.getDataLayout(), TLI, DT, AC}; 7362 } 7363 template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &, 7364 Function &); 7365 7366 bool SimplifyQuery::isUndefValue(Value *V) const { 7367 if (!CanUseUndef) 7368 return false; 7369 7370 return match(V, m_Undef()); 7371 } 7372 7373 } // namespace llvm 7374 7375 void InstSimplifyFolder::anchor() {} 7376