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/ValueTracking.h" 34 #include "llvm/Analysis/VectorUtils.h" 35 #include "llvm/IR/ConstantRange.h" 36 #include "llvm/IR/DataLayout.h" 37 #include "llvm/IR/Dominators.h" 38 #include "llvm/IR/InstrTypes.h" 39 #include "llvm/IR/Instructions.h" 40 #include "llvm/IR/Operator.h" 41 #include "llvm/IR/PatternMatch.h" 42 #include "llvm/Support/KnownBits.h" 43 #include <algorithm> 44 #include <optional> 45 using namespace llvm; 46 using namespace llvm::PatternMatch; 47 48 #define DEBUG_TYPE "instsimplify" 49 50 enum { RecursionLimit = 3 }; 51 52 STATISTIC(NumExpand, "Number of expansions"); 53 STATISTIC(NumReassoc, "Number of reassociations"); 54 55 static Value *simplifyAndInst(Value *, Value *, const SimplifyQuery &, 56 unsigned); 57 static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned); 58 static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &, 59 const SimplifyQuery &, unsigned); 60 static Value *simplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &, 61 unsigned); 62 static Value *simplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &, 63 const SimplifyQuery &, unsigned); 64 static Value *simplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &, 65 unsigned); 66 static Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 67 const SimplifyQuery &Q, unsigned MaxRecurse); 68 static Value *simplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned); 69 static Value *simplifyXorInst(Value *, Value *, const SimplifyQuery &, 70 unsigned); 71 static Value *simplifyCastInst(unsigned, Value *, Type *, const SimplifyQuery &, 72 unsigned); 73 static Value *simplifyGEPInst(Type *, Value *, ArrayRef<Value *>, bool, 74 const SimplifyQuery &, unsigned); 75 static Value *simplifySelectInst(Value *, Value *, Value *, 76 const SimplifyQuery &, unsigned); 77 static Value *simplifyInstructionWithOperands(Instruction *I, 78 ArrayRef<Value *> NewOps, 79 const SimplifyQuery &SQ, 80 unsigned MaxRecurse); 81 82 static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal, 83 Value *FalseVal) { 84 BinaryOperator::BinaryOps BinOpCode; 85 if (auto *BO = dyn_cast<BinaryOperator>(Cond)) 86 BinOpCode = BO->getOpcode(); 87 else 88 return nullptr; 89 90 CmpInst::Predicate ExpectedPred, Pred1, Pred2; 91 if (BinOpCode == BinaryOperator::Or) { 92 ExpectedPred = ICmpInst::ICMP_NE; 93 } else if (BinOpCode == BinaryOperator::And) { 94 ExpectedPred = ICmpInst::ICMP_EQ; 95 } else 96 return nullptr; 97 98 // %A = icmp eq %TV, %FV 99 // %B = icmp eq %X, %Y (and one of these is a select operand) 100 // %C = and %A, %B 101 // %D = select %C, %TV, %FV 102 // --> 103 // %FV 104 105 // %A = icmp ne %TV, %FV 106 // %B = icmp ne %X, %Y (and one of these is a select operand) 107 // %C = or %A, %B 108 // %D = select %C, %TV, %FV 109 // --> 110 // %TV 111 Value *X, *Y; 112 if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal), 113 m_Specific(FalseVal)), 114 m_ICmp(Pred2, m_Value(X), m_Value(Y)))) || 115 Pred1 != Pred2 || Pred1 != ExpectedPred) 116 return nullptr; 117 118 if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal) 119 return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal; 120 121 return nullptr; 122 } 123 124 /// For a boolean type or a vector of boolean type, return false or a vector 125 /// with every element false. 126 static Constant *getFalse(Type *Ty) { return ConstantInt::getFalse(Ty); } 127 128 /// For a boolean type or a vector of boolean type, return true or a vector 129 /// with every element true. 130 static Constant *getTrue(Type *Ty) { return ConstantInt::getTrue(Ty); } 131 132 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? 133 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, 134 Value *RHS) { 135 CmpInst *Cmp = dyn_cast<CmpInst>(V); 136 if (!Cmp) 137 return false; 138 CmpInst::Predicate CPred = Cmp->getPredicate(); 139 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); 140 if (CPred == Pred && CLHS == LHS && CRHS == RHS) 141 return true; 142 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && 143 CRHS == LHS; 144 } 145 146 /// Simplify comparison with true or false branch of select: 147 /// %sel = select i1 %cond, i32 %tv, i32 %fv 148 /// %cmp = icmp sle i32 %sel, %rhs 149 /// Compose new comparison by substituting %sel with either %tv or %fv 150 /// and see if it simplifies. 151 static Value *simplifyCmpSelCase(CmpInst::Predicate Pred, Value *LHS, 152 Value *RHS, Value *Cond, 153 const SimplifyQuery &Q, unsigned MaxRecurse, 154 Constant *TrueOrFalse) { 155 Value *SimplifiedCmp = simplifyCmpInst(Pred, LHS, RHS, Q, MaxRecurse); 156 if (SimplifiedCmp == Cond) { 157 // %cmp simplified to the select condition (%cond). 158 return TrueOrFalse; 159 } else if (!SimplifiedCmp && isSameCompare(Cond, Pred, LHS, RHS)) { 160 // It didn't simplify. However, if composed comparison is equivalent 161 // to the select condition (%cond) then we can replace it. 162 return TrueOrFalse; 163 } 164 return SimplifiedCmp; 165 } 166 167 /// Simplify comparison with true branch of select 168 static Value *simplifyCmpSelTrueCase(CmpInst::Predicate Pred, Value *LHS, 169 Value *RHS, Value *Cond, 170 const SimplifyQuery &Q, 171 unsigned MaxRecurse) { 172 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 173 getTrue(Cond->getType())); 174 } 175 176 /// Simplify comparison with false branch of select 177 static Value *simplifyCmpSelFalseCase(CmpInst::Predicate Pred, Value *LHS, 178 Value *RHS, Value *Cond, 179 const SimplifyQuery &Q, 180 unsigned MaxRecurse) { 181 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 182 getFalse(Cond->getType())); 183 } 184 185 /// We know comparison with both branches of select can be simplified, but they 186 /// are not equal. This routine handles some logical simplifications. 187 static Value *handleOtherCmpSelSimplifications(Value *TCmp, Value *FCmp, 188 Value *Cond, 189 const SimplifyQuery &Q, 190 unsigned MaxRecurse) { 191 // If the false value simplified to false, then the result of the compare 192 // is equal to "Cond && TCmp". This also catches the case when the false 193 // value simplified to false and the true value to true, returning "Cond". 194 // Folding select to and/or isn't poison-safe in general; impliesPoison 195 // checks whether folding it does not convert a well-defined value into 196 // poison. 197 if (match(FCmp, m_Zero()) && impliesPoison(TCmp, Cond)) 198 if (Value *V = simplifyAndInst(Cond, TCmp, Q, MaxRecurse)) 199 return V; 200 // If the true value simplified to true, then the result of the compare 201 // is equal to "Cond || FCmp". 202 if (match(TCmp, m_One()) && impliesPoison(FCmp, Cond)) 203 if (Value *V = simplifyOrInst(Cond, FCmp, Q, MaxRecurse)) 204 return V; 205 // Finally, if the false value simplified to true and the true value to 206 // false, then the result of the compare is equal to "!Cond". 207 if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 208 if (Value *V = simplifyXorInst( 209 Cond, Constant::getAllOnesValue(Cond->getType()), Q, MaxRecurse)) 210 return V; 211 return nullptr; 212 } 213 214 /// Does the given value dominate the specified phi node? 215 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 216 Instruction *I = dyn_cast<Instruction>(V); 217 if (!I) 218 // Arguments and constants dominate all instructions. 219 return true; 220 221 // If we have a DominatorTree then do a precise test. 222 if (DT) 223 return DT->dominates(I, P); 224 225 // Otherwise, if the instruction is in the entry block and is not an invoke, 226 // then it obviously dominates all phi nodes. 227 if (I->getParent()->isEntryBlock() && !isa<InvokeInst>(I) && 228 !isa<CallBrInst>(I)) 229 return true; 230 231 return false; 232 } 233 234 /// Try to simplify a binary operator of form "V op OtherOp" where V is 235 /// "(B0 opex B1)" by distributing 'op' across 'opex' as 236 /// "(B0 op OtherOp) opex (B1 op OtherOp)". 237 static Value *expandBinOp(Instruction::BinaryOps Opcode, Value *V, 238 Value *OtherOp, Instruction::BinaryOps OpcodeToExpand, 239 const SimplifyQuery &Q, unsigned MaxRecurse) { 240 auto *B = dyn_cast<BinaryOperator>(V); 241 if (!B || B->getOpcode() != OpcodeToExpand) 242 return nullptr; 243 Value *B0 = B->getOperand(0), *B1 = B->getOperand(1); 244 Value *L = 245 simplifyBinOp(Opcode, B0, OtherOp, Q.getWithoutUndef(), MaxRecurse); 246 if (!L) 247 return nullptr; 248 Value *R = 249 simplifyBinOp(Opcode, B1, OtherOp, Q.getWithoutUndef(), MaxRecurse); 250 if (!R) 251 return nullptr; 252 253 // Does the expanded pair of binops simplify to the existing binop? 254 if ((L == B0 && R == B1) || 255 (Instruction::isCommutative(OpcodeToExpand) && L == B1 && R == B0)) { 256 ++NumExpand; 257 return B; 258 } 259 260 // Otherwise, return "L op' R" if it simplifies. 261 Value *S = simplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse); 262 if (!S) 263 return nullptr; 264 265 ++NumExpand; 266 return S; 267 } 268 269 /// Try to simplify binops of form "A op (B op' C)" or the commuted variant by 270 /// distributing op over op'. 271 static Value *expandCommutativeBinOp(Instruction::BinaryOps Opcode, Value *L, 272 Value *R, 273 Instruction::BinaryOps OpcodeToExpand, 274 const SimplifyQuery &Q, 275 unsigned MaxRecurse) { 276 // Recursion is always used, so bail out at once if we already hit the limit. 277 if (!MaxRecurse--) 278 return nullptr; 279 280 if (Value *V = expandBinOp(Opcode, L, R, OpcodeToExpand, Q, MaxRecurse)) 281 return V; 282 if (Value *V = expandBinOp(Opcode, R, L, OpcodeToExpand, Q, MaxRecurse)) 283 return V; 284 return nullptr; 285 } 286 287 /// Generic simplifications for associative binary operations. 288 /// Returns the simpler value, or null if none was found. 289 static Value *simplifyAssociativeBinOp(Instruction::BinaryOps Opcode, 290 Value *LHS, Value *RHS, 291 const SimplifyQuery &Q, 292 unsigned MaxRecurse) { 293 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 294 295 // Recursion is always used, so bail out at once if we already hit the limit. 296 if (!MaxRecurse--) 297 return nullptr; 298 299 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 300 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 301 302 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 303 if (Op0 && Op0->getOpcode() == Opcode) { 304 Value *A = Op0->getOperand(0); 305 Value *B = Op0->getOperand(1); 306 Value *C = RHS; 307 308 // Does "B op C" simplify? 309 if (Value *V = simplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 310 // It does! Return "A op V" if it simplifies or is already available. 311 // If V equals B then "A op V" is just the LHS. 312 if (V == B) 313 return LHS; 314 // Otherwise return "A op V" if it simplifies. 315 if (Value *W = simplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { 316 ++NumReassoc; 317 return W; 318 } 319 } 320 } 321 322 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 323 if (Op1 && Op1->getOpcode() == Opcode) { 324 Value *A = LHS; 325 Value *B = Op1->getOperand(0); 326 Value *C = Op1->getOperand(1); 327 328 // Does "A op B" simplify? 329 if (Value *V = simplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { 330 // It does! Return "V op C" if it simplifies or is already available. 331 // If V equals B then "V op C" is just the RHS. 332 if (V == B) 333 return RHS; 334 // Otherwise return "V op C" if it simplifies. 335 if (Value *W = simplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { 336 ++NumReassoc; 337 return W; 338 } 339 } 340 } 341 342 // The remaining transforms require commutativity as well as associativity. 343 if (!Instruction::isCommutative(Opcode)) 344 return nullptr; 345 346 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 347 if (Op0 && Op0->getOpcode() == Opcode) { 348 Value *A = Op0->getOperand(0); 349 Value *B = Op0->getOperand(1); 350 Value *C = RHS; 351 352 // Does "C op A" simplify? 353 if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 354 // It does! Return "V op B" if it simplifies or is already available. 355 // If V equals A then "V op B" is just the LHS. 356 if (V == A) 357 return LHS; 358 // Otherwise return "V op B" if it simplifies. 359 if (Value *W = simplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { 360 ++NumReassoc; 361 return W; 362 } 363 } 364 } 365 366 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 367 if (Op1 && Op1->getOpcode() == Opcode) { 368 Value *A = LHS; 369 Value *B = Op1->getOperand(0); 370 Value *C = Op1->getOperand(1); 371 372 // Does "C op A" simplify? 373 if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 374 // It does! Return "B op V" if it simplifies or is already available. 375 // If V equals C then "B op V" is just the RHS. 376 if (V == C) 377 return RHS; 378 // Otherwise return "B op V" if it simplifies. 379 if (Value *W = simplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { 380 ++NumReassoc; 381 return W; 382 } 383 } 384 } 385 386 return nullptr; 387 } 388 389 /// In the case of a binary operation with a select instruction as an operand, 390 /// try to simplify the binop by seeing whether evaluating it on both branches 391 /// of the select results in the same value. Returns the common value if so, 392 /// otherwise returns null. 393 static Value *threadBinOpOverSelect(Instruction::BinaryOps Opcode, Value *LHS, 394 Value *RHS, const SimplifyQuery &Q, 395 unsigned MaxRecurse) { 396 // Recursion is always used, so bail out at once if we already hit the limit. 397 if (!MaxRecurse--) 398 return nullptr; 399 400 SelectInst *SI; 401 if (isa<SelectInst>(LHS)) { 402 SI = cast<SelectInst>(LHS); 403 } else { 404 assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 405 SI = cast<SelectInst>(RHS); 406 } 407 408 // Evaluate the BinOp on the true and false branches of the select. 409 Value *TV; 410 Value *FV; 411 if (SI == LHS) { 412 TV = simplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); 413 FV = simplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); 414 } else { 415 TV = simplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); 416 FV = simplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); 417 } 418 419 // If they simplified to the same value, then return the common value. 420 // If they both failed to simplify then return null. 421 if (TV == FV) 422 return TV; 423 424 // If one branch simplified to undef, return the other one. 425 if (TV && Q.isUndefValue(TV)) 426 return FV; 427 if (FV && Q.isUndefValue(FV)) 428 return TV; 429 430 // If applying the operation did not change the true and false select values, 431 // then the result of the binop is the select itself. 432 if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 433 return SI; 434 435 // If one branch simplified and the other did not, and the simplified 436 // value is equal to the unsimplified one, return the simplified value. 437 // For example, select (cond, X, X & Z) & Z -> X & Z. 438 if ((FV && !TV) || (TV && !FV)) { 439 // Check that the simplified value has the form "X op Y" where "op" is the 440 // same as the original operation. 441 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 442 if (Simplified && Simplified->getOpcode() == unsigned(Opcode)) { 443 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 444 // We already know that "op" is the same as for the simplified value. See 445 // if the operands match too. If so, return the simplified value. 446 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 447 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 448 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 449 if (Simplified->getOperand(0) == UnsimplifiedLHS && 450 Simplified->getOperand(1) == UnsimplifiedRHS) 451 return Simplified; 452 if (Simplified->isCommutative() && 453 Simplified->getOperand(1) == UnsimplifiedLHS && 454 Simplified->getOperand(0) == UnsimplifiedRHS) 455 return Simplified; 456 } 457 } 458 459 return nullptr; 460 } 461 462 /// In the case of a comparison with a select instruction, try to simplify the 463 /// comparison by seeing whether both branches of the select result in the same 464 /// value. Returns the common value if so, otherwise returns null. 465 /// For example, if we have: 466 /// %tmp = select i1 %cmp, i32 1, i32 2 467 /// %cmp1 = icmp sle i32 %tmp, 3 468 /// We can simplify %cmp1 to true, because both branches of select are 469 /// less than 3. We compose new comparison by substituting %tmp with both 470 /// branches of select and see if it can be simplified. 471 static Value *threadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 472 Value *RHS, const SimplifyQuery &Q, 473 unsigned MaxRecurse) { 474 // Recursion is always used, so bail out at once if we already hit the limit. 475 if (!MaxRecurse--) 476 return nullptr; 477 478 // Make sure the select is on the LHS. 479 if (!isa<SelectInst>(LHS)) { 480 std::swap(LHS, RHS); 481 Pred = CmpInst::getSwappedPredicate(Pred); 482 } 483 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 484 SelectInst *SI = cast<SelectInst>(LHS); 485 Value *Cond = SI->getCondition(); 486 Value *TV = SI->getTrueValue(); 487 Value *FV = SI->getFalseValue(); 488 489 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 490 // Does "cmp TV, RHS" simplify? 491 Value *TCmp = simplifyCmpSelTrueCase(Pred, TV, RHS, Cond, Q, MaxRecurse); 492 if (!TCmp) 493 return nullptr; 494 495 // Does "cmp FV, RHS" simplify? 496 Value *FCmp = simplifyCmpSelFalseCase(Pred, FV, RHS, Cond, Q, MaxRecurse); 497 if (!FCmp) 498 return nullptr; 499 500 // If both sides simplified to the same value, then use it as the result of 501 // the original comparison. 502 if (TCmp == FCmp) 503 return TCmp; 504 505 // The remaining cases only make sense if the select condition has the same 506 // type as the result of the comparison, so bail out if this is not so. 507 if (Cond->getType()->isVectorTy() == RHS->getType()->isVectorTy()) 508 return handleOtherCmpSelSimplifications(TCmp, FCmp, Cond, Q, MaxRecurse); 509 510 return nullptr; 511 } 512 513 /// In the case of a binary operation with an operand that is a PHI instruction, 514 /// try to simplify the binop by seeing whether evaluating it on the incoming 515 /// phi values yields the same result for every value. If so returns the common 516 /// value, otherwise returns null. 517 static Value *threadBinOpOverPHI(Instruction::BinaryOps Opcode, Value *LHS, 518 Value *RHS, const SimplifyQuery &Q, 519 unsigned MaxRecurse) { 520 // Recursion is always used, so bail out at once if we already hit the limit. 521 if (!MaxRecurse--) 522 return nullptr; 523 524 PHINode *PI; 525 if (isa<PHINode>(LHS)) { 526 PI = cast<PHINode>(LHS); 527 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 528 if (!valueDominatesPHI(RHS, PI, Q.DT)) 529 return nullptr; 530 } else { 531 assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 532 PI = cast<PHINode>(RHS); 533 // Bail out if LHS and the phi may be mutually interdependent due to a loop. 534 if (!valueDominatesPHI(LHS, PI, Q.DT)) 535 return nullptr; 536 } 537 538 // Evaluate the BinOp on the incoming phi values. 539 Value *CommonValue = nullptr; 540 for (Use &Incoming : PI->incoming_values()) { 541 // If the incoming value is the phi node itself, it can safely be skipped. 542 if (Incoming == PI) 543 continue; 544 Instruction *InTI = PI->getIncomingBlock(Incoming)->getTerminator(); 545 Value *V = PI == LHS 546 ? simplifyBinOp(Opcode, Incoming, RHS, 547 Q.getWithInstruction(InTI), MaxRecurse) 548 : simplifyBinOp(Opcode, LHS, Incoming, 549 Q.getWithInstruction(InTI), MaxRecurse); 550 // If the operation failed to simplify, or simplified to a different value 551 // to previously, then give up. 552 if (!V || (CommonValue && V != CommonValue)) 553 return nullptr; 554 CommonValue = V; 555 } 556 557 return CommonValue; 558 } 559 560 /// In the case of a comparison with a PHI instruction, try to simplify the 561 /// comparison by seeing whether comparing with all of the incoming phi values 562 /// yields the same result every time. If so returns the common result, 563 /// otherwise returns null. 564 static Value *threadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 565 const SimplifyQuery &Q, unsigned MaxRecurse) { 566 // Recursion is always used, so bail out at once if we already hit the limit. 567 if (!MaxRecurse--) 568 return nullptr; 569 570 // Make sure the phi is on the LHS. 571 if (!isa<PHINode>(LHS)) { 572 std::swap(LHS, RHS); 573 Pred = CmpInst::getSwappedPredicate(Pred); 574 } 575 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 576 PHINode *PI = cast<PHINode>(LHS); 577 578 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 579 if (!valueDominatesPHI(RHS, PI, Q.DT)) 580 return nullptr; 581 582 // Evaluate the BinOp on the incoming phi values. 583 Value *CommonValue = nullptr; 584 for (unsigned u = 0, e = PI->getNumIncomingValues(); u < e; ++u) { 585 Value *Incoming = PI->getIncomingValue(u); 586 Instruction *InTI = PI->getIncomingBlock(u)->getTerminator(); 587 // If the incoming value is the phi node itself, it can safely be skipped. 588 if (Incoming == PI) 589 continue; 590 // Change the context instruction to the "edge" that flows into the phi. 591 // This is important because that is where incoming is actually "evaluated" 592 // even though it is used later somewhere else. 593 Value *V = simplifyCmpInst(Pred, Incoming, RHS, Q.getWithInstruction(InTI), 594 MaxRecurse); 595 // If the operation failed to simplify, or simplified to a different value 596 // to previously, then give up. 597 if (!V || (CommonValue && V != CommonValue)) 598 return nullptr; 599 CommonValue = V; 600 } 601 602 return CommonValue; 603 } 604 605 static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode, 606 Value *&Op0, Value *&Op1, 607 const SimplifyQuery &Q) { 608 if (auto *CLHS = dyn_cast<Constant>(Op0)) { 609 if (auto *CRHS = dyn_cast<Constant>(Op1)) { 610 switch (Opcode) { 611 default: 612 break; 613 case Instruction::FAdd: 614 case Instruction::FSub: 615 case Instruction::FMul: 616 case Instruction::FDiv: 617 case Instruction::FRem: 618 if (Q.CxtI != nullptr) 619 return ConstantFoldFPInstOperands(Opcode, CLHS, CRHS, Q.DL, Q.CxtI); 620 } 621 return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL); 622 } 623 624 // Canonicalize the constant to the RHS if this is a commutative operation. 625 if (Instruction::isCommutative(Opcode)) 626 std::swap(Op0, Op1); 627 } 628 return nullptr; 629 } 630 631 /// Given operands for an Add, see if we can fold the result. 632 /// If not, this returns null. 633 static Value *simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 634 const SimplifyQuery &Q, unsigned MaxRecurse) { 635 if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q)) 636 return C; 637 638 // X + poison -> poison 639 if (isa<PoisonValue>(Op1)) 640 return Op1; 641 642 // X + undef -> undef 643 if (Q.isUndefValue(Op1)) 644 return Op1; 645 646 // X + 0 -> X 647 if (match(Op1, m_Zero())) 648 return Op0; 649 650 // If two operands are negative, return 0. 651 if (isKnownNegation(Op0, Op1)) 652 return Constant::getNullValue(Op0->getType()); 653 654 // X + (Y - X) -> Y 655 // (Y - X) + X -> Y 656 // Eg: X + -X -> 0 657 Value *Y = nullptr; 658 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 659 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 660 return Y; 661 662 // X + ~X -> -1 since ~X = -X-1 663 Type *Ty = Op0->getType(); 664 if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0)))) 665 return Constant::getAllOnesValue(Ty); 666 667 // add nsw/nuw (xor Y, signmask), signmask --> Y 668 // The no-wrapping add guarantees that the top bit will be set by the add. 669 // Therefore, the xor must be clearing the already set sign bit of Y. 670 if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) && 671 match(Op0, m_Xor(m_Value(Y), m_SignMask()))) 672 return Y; 673 674 // add nuw %x, -1 -> -1, because %x can only be 0. 675 if (IsNUW && match(Op1, m_AllOnes())) 676 return Op1; // Which is -1. 677 678 /// i1 add -> xor. 679 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 680 if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1)) 681 return V; 682 683 // Try some generic simplifications for associative operations. 684 if (Value *V = 685 simplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, MaxRecurse)) 686 return V; 687 688 // Threading Add over selects and phi nodes is pointless, so don't bother. 689 // Threading over the select in "A + select(cond, B, C)" means evaluating 690 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 691 // only if B and C are equal. If B and C are equal then (since we assume 692 // that operands have already been simplified) "select(cond, B, C)" should 693 // have been simplified to the common value of B and C already. Analysing 694 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 695 // for threading over phi nodes. 696 697 return nullptr; 698 } 699 700 Value *llvm::simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 701 const SimplifyQuery &Query) { 702 return ::simplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit); 703 } 704 705 /// Compute the base pointer and cumulative constant offsets for V. 706 /// 707 /// This strips all constant offsets off of V, leaving it the base pointer, and 708 /// accumulates the total constant offset applied in the returned constant. 709 /// It returns zero if there are no constant offsets applied. 710 /// 711 /// This is very similar to stripAndAccumulateConstantOffsets(), except it 712 /// normalizes the offset bitwidth to the stripped pointer type, not the 713 /// original pointer type. 714 static APInt stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V, 715 bool AllowNonInbounds = false) { 716 assert(V->getType()->isPtrOrPtrVectorTy()); 717 718 APInt Offset = APInt::getZero(DL.getIndexTypeSizeInBits(V->getType())); 719 V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds); 720 // As that strip may trace through `addrspacecast`, need to sext or trunc 721 // the offset calculated. 722 return Offset.sextOrTrunc(DL.getIndexTypeSizeInBits(V->getType())); 723 } 724 725 /// Compute the constant difference between two pointer values. 726 /// If the difference is not a constant, returns zero. 727 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS, 728 Value *RHS) { 729 APInt LHSOffset = stripAndComputeConstantOffsets(DL, LHS); 730 APInt RHSOffset = stripAndComputeConstantOffsets(DL, RHS); 731 732 // If LHS and RHS are not related via constant offsets to the same base 733 // value, there is nothing we can do here. 734 if (LHS != RHS) 735 return nullptr; 736 737 // Otherwise, the difference of LHS - RHS can be computed as: 738 // LHS - RHS 739 // = (LHSOffset + Base) - (RHSOffset + Base) 740 // = LHSOffset - RHSOffset 741 Constant *Res = ConstantInt::get(LHS->getContext(), LHSOffset - RHSOffset); 742 if (auto *VecTy = dyn_cast<VectorType>(LHS->getType())) 743 Res = ConstantVector::getSplat(VecTy->getElementCount(), Res); 744 return Res; 745 } 746 747 /// Test if there is a dominating equivalence condition for the 748 /// two operands. If there is, try to reduce the binary operation 749 /// between the two operands. 750 /// Example: Op0 - Op1 --> 0 when Op0 == Op1 751 static Value *simplifyByDomEq(unsigned Opcode, Value *Op0, Value *Op1, 752 const SimplifyQuery &Q, unsigned MaxRecurse) { 753 // Recursive run it can not get any benefit 754 if (MaxRecurse != RecursionLimit) 755 return nullptr; 756 757 std::optional<bool> Imp = 758 isImpliedByDomCondition(CmpInst::ICMP_EQ, Op0, Op1, Q.CxtI, Q.DL); 759 if (Imp && *Imp) { 760 Type *Ty = Op0->getType(); 761 switch (Opcode) { 762 case Instruction::Sub: 763 case Instruction::Xor: 764 case Instruction::URem: 765 case Instruction::SRem: 766 return Constant::getNullValue(Ty); 767 768 case Instruction::SDiv: 769 case Instruction::UDiv: 770 return ConstantInt::get(Ty, 1); 771 772 case Instruction::And: 773 case Instruction::Or: 774 // Could be either one - choose Op1 since that's more likely a constant. 775 return Op1; 776 default: 777 break; 778 } 779 } 780 return nullptr; 781 } 782 783 /// Given operands for a Sub, see if we can fold the result. 784 /// If not, this returns null. 785 static Value *simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 786 const SimplifyQuery &Q, unsigned MaxRecurse) { 787 if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q)) 788 return C; 789 790 // X - poison -> poison 791 // poison - X -> poison 792 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 793 return PoisonValue::get(Op0->getType()); 794 795 // X - undef -> undef 796 // undef - X -> undef 797 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 798 return UndefValue::get(Op0->getType()); 799 800 // X - 0 -> X 801 if (match(Op1, m_Zero())) 802 return Op0; 803 804 // X - X -> 0 805 if (Op0 == Op1) 806 return Constant::getNullValue(Op0->getType()); 807 808 // Is this a negation? 809 if (match(Op0, m_Zero())) { 810 // 0 - X -> 0 if the sub is NUW. 811 if (IsNUW) 812 return Constant::getNullValue(Op0->getType()); 813 814 KnownBits Known = computeKnownBits(Op1, /* Depth */ 0, Q); 815 if (Known.Zero.isMaxSignedValue()) { 816 // Op1 is either 0 or the minimum signed value. If the sub is NSW, then 817 // Op1 must be 0 because negating the minimum signed value is undefined. 818 if (IsNSW) 819 return Constant::getNullValue(Op0->getType()); 820 821 // 0 - X -> X if X is 0 or the minimum signed value. 822 return Op1; 823 } 824 } 825 826 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 827 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 828 Value *X = nullptr, *Y = nullptr, *Z = Op1; 829 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 830 // See if "V === Y - Z" simplifies. 831 if (Value *V = simplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse - 1)) 832 // It does! Now see if "X + V" simplifies. 833 if (Value *W = simplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse - 1)) { 834 // It does, we successfully reassociated! 835 ++NumReassoc; 836 return W; 837 } 838 // See if "V === X - Z" simplifies. 839 if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1)) 840 // It does! Now see if "Y + V" simplifies. 841 if (Value *W = simplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse - 1)) { 842 // It does, we successfully reassociated! 843 ++NumReassoc; 844 return W; 845 } 846 } 847 848 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 849 // For example, X - (X + 1) -> -1 850 X = Op0; 851 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 852 // See if "V === X - Y" simplifies. 853 if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1)) 854 // It does! Now see if "V - Z" simplifies. 855 if (Value *W = simplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse - 1)) { 856 // It does, we successfully reassociated! 857 ++NumReassoc; 858 return W; 859 } 860 // See if "V === X - Z" simplifies. 861 if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1)) 862 // It does! Now see if "V - Y" simplifies. 863 if (Value *W = simplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse - 1)) { 864 // It does, we successfully reassociated! 865 ++NumReassoc; 866 return W; 867 } 868 } 869 870 // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 871 // For example, X - (X - Y) -> Y. 872 Z = Op0; 873 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 874 // See if "V === Z - X" simplifies. 875 if (Value *V = simplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse - 1)) 876 // It does! Now see if "V + Y" simplifies. 877 if (Value *W = simplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse - 1)) { 878 // It does, we successfully reassociated! 879 ++NumReassoc; 880 return W; 881 } 882 883 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. 884 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && 885 match(Op1, m_Trunc(m_Value(Y)))) 886 if (X->getType() == Y->getType()) 887 // See if "V === X - Y" simplifies. 888 if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1)) 889 // It does! Now see if "trunc V" simplifies. 890 if (Value *W = simplifyCastInst(Instruction::Trunc, V, Op0->getType(), 891 Q, MaxRecurse - 1)) 892 // It does, return the simplified "trunc V". 893 return W; 894 895 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). 896 if (match(Op0, m_PtrToInt(m_Value(X))) && match(Op1, m_PtrToInt(m_Value(Y)))) 897 if (Constant *Result = computePointerDifference(Q.DL, X, Y)) 898 return ConstantFoldIntegerCast(Result, Op0->getType(), /*IsSigned*/ true, 899 Q.DL); 900 901 // i1 sub -> xor. 902 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 903 if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1)) 904 return V; 905 906 // Threading Sub over selects and phi nodes is pointless, so don't bother. 907 // Threading over the select in "A - select(cond, B, C)" means evaluating 908 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 909 // only if B and C are equal. If B and C are equal then (since we assume 910 // that operands have already been simplified) "select(cond, B, C)" should 911 // have been simplified to the common value of B and C already. Analysing 912 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 913 // for threading over phi nodes. 914 915 if (Value *V = simplifyByDomEq(Instruction::Sub, Op0, Op1, Q, MaxRecurse)) 916 return V; 917 918 return nullptr; 919 } 920 921 Value *llvm::simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 922 const SimplifyQuery &Q) { 923 return ::simplifySubInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 924 } 925 926 /// Given operands for a Mul, see if we can fold the result. 927 /// If not, this returns null. 928 static Value *simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 929 const SimplifyQuery &Q, unsigned MaxRecurse) { 930 if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q)) 931 return C; 932 933 // X * poison -> poison 934 if (isa<PoisonValue>(Op1)) 935 return Op1; 936 937 // X * undef -> 0 938 // X * 0 -> 0 939 if (Q.isUndefValue(Op1) || match(Op1, m_Zero())) 940 return Constant::getNullValue(Op0->getType()); 941 942 // X * 1 -> X 943 if (match(Op1, m_One())) 944 return Op0; 945 946 // (X / Y) * Y -> X if the division is exact. 947 Value *X = nullptr; 948 if (Q.IIQ.UseInstrInfo && 949 (match(Op0, 950 m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y 951 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))) // Y * (X / Y) 952 return X; 953 954 if (Op0->getType()->isIntOrIntVectorTy(1)) { 955 // mul i1 nsw is a special-case because -1 * -1 is poison (+1 is not 956 // representable). All other cases reduce to 0, so just return 0. 957 if (IsNSW) 958 return ConstantInt::getNullValue(Op0->getType()); 959 960 // Treat "mul i1" as "and i1". 961 if (MaxRecurse) 962 if (Value *V = simplifyAndInst(Op0, Op1, Q, MaxRecurse - 1)) 963 return V; 964 } 965 966 // Try some generic simplifications for associative operations. 967 if (Value *V = 968 simplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 969 return V; 970 971 // Mul distributes over Add. Try some generic simplifications based on this. 972 if (Value *V = expandCommutativeBinOp(Instruction::Mul, Op0, Op1, 973 Instruction::Add, Q, MaxRecurse)) 974 return V; 975 976 // If the operation is with the result of a select instruction, check whether 977 // operating on either branch of the select always yields the same value. 978 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 979 if (Value *V = 980 threadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 981 return V; 982 983 // If the operation is with the result of a phi instruction, check whether 984 // operating on all incoming values of the phi always yields the same value. 985 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 986 if (Value *V = 987 threadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 988 return V; 989 990 return nullptr; 991 } 992 993 Value *llvm::simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 994 const SimplifyQuery &Q) { 995 return ::simplifyMulInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 996 } 997 998 /// Given a predicate and two operands, return true if the comparison is true. 999 /// This is a helper for div/rem simplification where we return some other value 1000 /// when we can prove a relationship between the operands. 1001 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS, 1002 const SimplifyQuery &Q, unsigned MaxRecurse) { 1003 Value *V = simplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse); 1004 Constant *C = dyn_cast_or_null<Constant>(V); 1005 return (C && C->isAllOnesValue()); 1006 } 1007 1008 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer 1009 /// to simplify X % Y to X. 1010 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q, 1011 unsigned MaxRecurse, bool IsSigned) { 1012 // Recursion is always used, so bail out at once if we already hit the limit. 1013 if (!MaxRecurse--) 1014 return false; 1015 1016 if (IsSigned) { 1017 // (X srem Y) sdiv Y --> 0 1018 if (match(X, m_SRem(m_Value(), m_Specific(Y)))) 1019 return true; 1020 1021 // |X| / |Y| --> 0 1022 // 1023 // We require that 1 operand is a simple constant. That could be extended to 1024 // 2 variables if we computed the sign bit for each. 1025 // 1026 // Make sure that a constant is not the minimum signed value because taking 1027 // the abs() of that is undefined. 1028 Type *Ty = X->getType(); 1029 const APInt *C; 1030 if (match(X, m_APInt(C)) && !C->isMinSignedValue()) { 1031 // Is the variable divisor magnitude always greater than the constant 1032 // dividend magnitude? 1033 // |Y| > |C| --> Y < -abs(C) or Y > abs(C) 1034 Constant *PosDividendC = ConstantInt::get(Ty, C->abs()); 1035 Constant *NegDividendC = ConstantInt::get(Ty, -C->abs()); 1036 if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) || 1037 isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse)) 1038 return true; 1039 } 1040 if (match(Y, m_APInt(C))) { 1041 // Special-case: we can't take the abs() of a minimum signed value. If 1042 // that's the divisor, then all we have to do is prove that the dividend 1043 // is also not the minimum signed value. 1044 if (C->isMinSignedValue()) 1045 return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse); 1046 1047 // Is the variable dividend magnitude always less than the constant 1048 // divisor magnitude? 1049 // |X| < |C| --> X > -abs(C) and X < abs(C) 1050 Constant *PosDivisorC = ConstantInt::get(Ty, C->abs()); 1051 Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs()); 1052 if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) && 1053 isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse)) 1054 return true; 1055 } 1056 return false; 1057 } 1058 1059 // IsSigned == false. 1060 1061 // Is the unsigned dividend known to be less than a constant divisor? 1062 // TODO: Convert this (and above) to range analysis 1063 // ("computeConstantRangeIncludingKnownBits")? 1064 const APInt *C; 1065 if (match(Y, m_APInt(C)) && 1066 computeKnownBits(X, /* Depth */ 0, Q).getMaxValue().ult(*C)) 1067 return true; 1068 1069 // Try again for any divisor: 1070 // Is the dividend unsigned less than the divisor? 1071 return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse); 1072 } 1073 1074 /// Check for common or similar folds of integer division or integer remainder. 1075 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem). 1076 static Value *simplifyDivRem(Instruction::BinaryOps Opcode, Value *Op0, 1077 Value *Op1, const SimplifyQuery &Q, 1078 unsigned MaxRecurse) { 1079 bool IsDiv = (Opcode == Instruction::SDiv || Opcode == Instruction::UDiv); 1080 bool IsSigned = (Opcode == Instruction::SDiv || Opcode == Instruction::SRem); 1081 1082 Type *Ty = Op0->getType(); 1083 1084 // X / undef -> poison 1085 // X % undef -> poison 1086 if (Q.isUndefValue(Op1) || isa<PoisonValue>(Op1)) 1087 return PoisonValue::get(Ty); 1088 1089 // X / 0 -> poison 1090 // X % 0 -> poison 1091 // We don't need to preserve faults! 1092 if (match(Op1, m_Zero())) 1093 return PoisonValue::get(Ty); 1094 1095 // If any element of a constant divisor fixed width vector is zero or undef 1096 // the behavior is undefined and we can fold the whole op to poison. 1097 auto *Op1C = dyn_cast<Constant>(Op1); 1098 auto *VTy = dyn_cast<FixedVectorType>(Ty); 1099 if (Op1C && VTy) { 1100 unsigned NumElts = VTy->getNumElements(); 1101 for (unsigned i = 0; i != NumElts; ++i) { 1102 Constant *Elt = Op1C->getAggregateElement(i); 1103 if (Elt && (Elt->isNullValue() || Q.isUndefValue(Elt))) 1104 return PoisonValue::get(Ty); 1105 } 1106 } 1107 1108 // poison / X -> poison 1109 // poison % X -> poison 1110 if (isa<PoisonValue>(Op0)) 1111 return Op0; 1112 1113 // undef / X -> 0 1114 // undef % X -> 0 1115 if (Q.isUndefValue(Op0)) 1116 return Constant::getNullValue(Ty); 1117 1118 // 0 / X -> 0 1119 // 0 % X -> 0 1120 if (match(Op0, m_Zero())) 1121 return Constant::getNullValue(Op0->getType()); 1122 1123 // X / X -> 1 1124 // X % X -> 0 1125 if (Op0 == Op1) 1126 return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty); 1127 1128 KnownBits Known = computeKnownBits(Op1, /* Depth */ 0, Q); 1129 // X / 0 -> poison 1130 // X % 0 -> poison 1131 // If the divisor is known to be zero, just return poison. This can happen in 1132 // some cases where its provable indirectly the denominator is zero but it's 1133 // not trivially simplifiable (i.e known zero through a phi node). 1134 if (Known.isZero()) 1135 return PoisonValue::get(Ty); 1136 1137 // X / 1 -> X 1138 // X % 1 -> 0 1139 // If the divisor can only be zero or one, we can't have division-by-zero 1140 // or remainder-by-zero, so assume the divisor is 1. 1141 // e.g. 1, zext (i8 X), sdiv X (Y and 1) 1142 if (Known.countMinLeadingZeros() == Known.getBitWidth() - 1) 1143 return IsDiv ? Op0 : Constant::getNullValue(Ty); 1144 1145 // If X * Y does not overflow, then: 1146 // X * Y / Y -> X 1147 // X * Y % Y -> 0 1148 Value *X; 1149 if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) { 1150 auto *Mul = cast<OverflowingBinaryOperator>(Op0); 1151 // The multiplication can't overflow if it is defined not to, or if 1152 // X == A / Y for some A. 1153 if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) || 1154 (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)) || 1155 (IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) || 1156 (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) { 1157 return IsDiv ? X : Constant::getNullValue(Op0->getType()); 1158 } 1159 } 1160 1161 if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned)) 1162 return IsDiv ? Constant::getNullValue(Op0->getType()) : Op0; 1163 1164 if (Value *V = simplifyByDomEq(Opcode, Op0, Op1, Q, MaxRecurse)) 1165 return V; 1166 1167 // If the operation is with the result of a select instruction, check whether 1168 // operating on either branch of the select always yields the same value. 1169 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1170 if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1171 return V; 1172 1173 // If the operation is with the result of a phi instruction, check whether 1174 // operating on all incoming values of the phi always yields the same value. 1175 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1176 if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1177 return V; 1178 1179 return nullptr; 1180 } 1181 1182 /// These are simplifications common to SDiv and UDiv. 1183 static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1184 bool IsExact, const SimplifyQuery &Q, 1185 unsigned MaxRecurse) { 1186 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1187 return C; 1188 1189 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse)) 1190 return V; 1191 1192 const APInt *DivC; 1193 if (IsExact && match(Op1, m_APInt(DivC))) { 1194 // If this is an exact divide by a constant, then the dividend (Op0) must 1195 // have at least as many trailing zeros as the divisor to divide evenly. If 1196 // it has less trailing zeros, then the result must be poison. 1197 if (DivC->countr_zero()) { 1198 KnownBits KnownOp0 = computeKnownBits(Op0, /* Depth */ 0, Q); 1199 if (KnownOp0.countMaxTrailingZeros() < DivC->countr_zero()) 1200 return PoisonValue::get(Op0->getType()); 1201 } 1202 1203 // udiv exact (mul nsw X, C), C --> X 1204 // sdiv exact (mul nuw X, C), C --> X 1205 // where C is not a power of 2. 1206 Value *X; 1207 if (!DivC->isPowerOf2() && 1208 (Opcode == Instruction::UDiv 1209 ? match(Op0, m_NSWMul(m_Value(X), m_Specific(Op1))) 1210 : match(Op0, m_NUWMul(m_Value(X), m_Specific(Op1))))) 1211 return X; 1212 } 1213 1214 return nullptr; 1215 } 1216 1217 /// These are simplifications common to SRem and URem. 1218 static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1219 const SimplifyQuery &Q, unsigned MaxRecurse) { 1220 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1221 return C; 1222 1223 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse)) 1224 return V; 1225 1226 // (X << Y) % X -> 0 1227 if (Q.IIQ.UseInstrInfo && 1228 ((Opcode == Instruction::SRem && 1229 match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) || 1230 (Opcode == Instruction::URem && 1231 match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))) 1232 return Constant::getNullValue(Op0->getType()); 1233 1234 return nullptr; 1235 } 1236 1237 /// Given operands for an SDiv, see if we can fold the result. 1238 /// If not, this returns null. 1239 static Value *simplifySDivInst(Value *Op0, Value *Op1, bool IsExact, 1240 const SimplifyQuery &Q, unsigned MaxRecurse) { 1241 // If two operands are negated and no signed overflow, return -1. 1242 if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true)) 1243 return Constant::getAllOnesValue(Op0->getType()); 1244 1245 return simplifyDiv(Instruction::SDiv, Op0, Op1, IsExact, Q, MaxRecurse); 1246 } 1247 1248 Value *llvm::simplifySDivInst(Value *Op0, Value *Op1, bool IsExact, 1249 const SimplifyQuery &Q) { 1250 return ::simplifySDivInst(Op0, Op1, IsExact, Q, RecursionLimit); 1251 } 1252 1253 /// Given operands for a UDiv, see if we can fold the result. 1254 /// If not, this returns null. 1255 static Value *simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact, 1256 const SimplifyQuery &Q, unsigned MaxRecurse) { 1257 return simplifyDiv(Instruction::UDiv, Op0, Op1, IsExact, Q, MaxRecurse); 1258 } 1259 1260 Value *llvm::simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact, 1261 const SimplifyQuery &Q) { 1262 return ::simplifyUDivInst(Op0, Op1, IsExact, Q, RecursionLimit); 1263 } 1264 1265 /// Given operands for an SRem, see if we can fold the result. 1266 /// If not, this returns null. 1267 static Value *simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1268 unsigned MaxRecurse) { 1269 // If the divisor is 0, the result is undefined, so assume the divisor is -1. 1270 // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0 1271 Value *X; 1272 if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) 1273 return ConstantInt::getNullValue(Op0->getType()); 1274 1275 // If the two operands are negated, return 0. 1276 if (isKnownNegation(Op0, Op1)) 1277 return ConstantInt::getNullValue(Op0->getType()); 1278 1279 return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse); 1280 } 1281 1282 Value *llvm::simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1283 return ::simplifySRemInst(Op0, Op1, Q, RecursionLimit); 1284 } 1285 1286 /// Given operands for a URem, see if we can fold the result. 1287 /// If not, this returns null. 1288 static Value *simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1289 unsigned MaxRecurse) { 1290 return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse); 1291 } 1292 1293 Value *llvm::simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1294 return ::simplifyURemInst(Op0, Op1, Q, RecursionLimit); 1295 } 1296 1297 /// Returns true if a shift by \c Amount always yields poison. 1298 static bool isPoisonShift(Value *Amount, const SimplifyQuery &Q) { 1299 Constant *C = dyn_cast<Constant>(Amount); 1300 if (!C) 1301 return false; 1302 1303 // X shift by undef -> poison because it may shift by the bitwidth. 1304 if (Q.isUndefValue(C)) 1305 return true; 1306 1307 // Shifting by the bitwidth or more is poison. This covers scalars and 1308 // fixed/scalable vectors with splat constants. 1309 const APInt *AmountC; 1310 if (match(C, m_APInt(AmountC)) && AmountC->uge(AmountC->getBitWidth())) 1311 return true; 1312 1313 // Try harder for fixed-length vectors: 1314 // If all lanes of a vector shift are poison, the whole shift is poison. 1315 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) { 1316 for (unsigned I = 0, 1317 E = cast<FixedVectorType>(C->getType())->getNumElements(); 1318 I != E; ++I) 1319 if (!isPoisonShift(C->getAggregateElement(I), Q)) 1320 return false; 1321 return true; 1322 } 1323 1324 return false; 1325 } 1326 1327 /// Given operands for an Shl, LShr or AShr, see if we can fold the result. 1328 /// If not, this returns null. 1329 static Value *simplifyShift(Instruction::BinaryOps Opcode, Value *Op0, 1330 Value *Op1, bool IsNSW, const SimplifyQuery &Q, 1331 unsigned MaxRecurse) { 1332 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1333 return C; 1334 1335 // poison shift by X -> poison 1336 if (isa<PoisonValue>(Op0)) 1337 return Op0; 1338 1339 // 0 shift by X -> 0 1340 if (match(Op0, m_Zero())) 1341 return Constant::getNullValue(Op0->getType()); 1342 1343 // X shift by 0 -> X 1344 // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones 1345 // would be poison. 1346 Value *X; 1347 if (match(Op1, m_Zero()) || 1348 (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) 1349 return Op0; 1350 1351 // Fold undefined shifts. 1352 if (isPoisonShift(Op1, Q)) 1353 return PoisonValue::get(Op0->getType()); 1354 1355 // If the operation is with the result of a select instruction, check whether 1356 // operating on either branch of the select always yields the same value. 1357 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1358 if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1359 return V; 1360 1361 // If the operation is with the result of a phi instruction, check whether 1362 // operating on all incoming values of the phi always yields the same value. 1363 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1364 if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1365 return V; 1366 1367 // If any bits in the shift amount make that value greater than or equal to 1368 // the number of bits in the type, the shift is undefined. 1369 KnownBits KnownAmt = computeKnownBits(Op1, /* Depth */ 0, Q); 1370 if (KnownAmt.getMinValue().uge(KnownAmt.getBitWidth())) 1371 return PoisonValue::get(Op0->getType()); 1372 1373 // If all valid bits in the shift amount are known zero, the first operand is 1374 // unchanged. 1375 unsigned NumValidShiftBits = Log2_32_Ceil(KnownAmt.getBitWidth()); 1376 if (KnownAmt.countMinTrailingZeros() >= NumValidShiftBits) 1377 return Op0; 1378 1379 // Check for nsw shl leading to a poison value. 1380 if (IsNSW) { 1381 assert(Opcode == Instruction::Shl && "Expected shl for nsw instruction"); 1382 KnownBits KnownVal = computeKnownBits(Op0, /* Depth */ 0, Q); 1383 KnownBits KnownShl = KnownBits::shl(KnownVal, KnownAmt); 1384 1385 if (KnownVal.Zero.isSignBitSet()) 1386 KnownShl.Zero.setSignBit(); 1387 if (KnownVal.One.isSignBitSet()) 1388 KnownShl.One.setSignBit(); 1389 1390 if (KnownShl.hasConflict()) 1391 return PoisonValue::get(Op0->getType()); 1392 } 1393 1394 return nullptr; 1395 } 1396 1397 /// Given operands for an LShr or AShr, see if we can fold the result. If not, 1398 /// this returns null. 1399 static Value *simplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0, 1400 Value *Op1, bool IsExact, 1401 const SimplifyQuery &Q, unsigned MaxRecurse) { 1402 if (Value *V = 1403 simplifyShift(Opcode, Op0, Op1, /*IsNSW*/ false, Q, MaxRecurse)) 1404 return V; 1405 1406 // X >> X -> 0 1407 if (Op0 == Op1) 1408 return Constant::getNullValue(Op0->getType()); 1409 1410 // undef >> X -> 0 1411 // undef >> X -> undef (if it's exact) 1412 if (Q.isUndefValue(Op0)) 1413 return IsExact ? Op0 : Constant::getNullValue(Op0->getType()); 1414 1415 // The low bit cannot be shifted out of an exact shift if it is set. 1416 // TODO: Generalize by counting trailing zeros (see fold for exact division). 1417 if (IsExact) { 1418 KnownBits Op0Known = computeKnownBits(Op0, /* Depth */ 0, Q); 1419 if (Op0Known.One[0]) 1420 return Op0; 1421 } 1422 1423 return nullptr; 1424 } 1425 1426 /// Given operands for an Shl, see if we can fold the result. 1427 /// If not, this returns null. 1428 static Value *simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 1429 const SimplifyQuery &Q, unsigned MaxRecurse) { 1430 if (Value *V = 1431 simplifyShift(Instruction::Shl, Op0, Op1, IsNSW, Q, MaxRecurse)) 1432 return V; 1433 1434 Type *Ty = Op0->getType(); 1435 // undef << X -> 0 1436 // undef << X -> undef if (if it's NSW/NUW) 1437 if (Q.isUndefValue(Op0)) 1438 return IsNSW || IsNUW ? Op0 : Constant::getNullValue(Ty); 1439 1440 // (X >> A) << A -> X 1441 Value *X; 1442 if (Q.IIQ.UseInstrInfo && 1443 match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) 1444 return X; 1445 1446 // shl nuw i8 C, %x -> C iff C has sign bit set. 1447 if (IsNUW && match(Op0, m_Negative())) 1448 return Op0; 1449 // NOTE: could use computeKnownBits() / LazyValueInfo, 1450 // but the cost-benefit analysis suggests it isn't worth it. 1451 1452 // "nuw" guarantees that only zeros are shifted out, and "nsw" guarantees 1453 // that the sign-bit does not change, so the only input that does not 1454 // produce poison is 0, and "0 << (bitwidth-1) --> 0". 1455 if (IsNSW && IsNUW && 1456 match(Op1, m_SpecificInt(Ty->getScalarSizeInBits() - 1))) 1457 return Constant::getNullValue(Ty); 1458 1459 return nullptr; 1460 } 1461 1462 Value *llvm::simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 1463 const SimplifyQuery &Q) { 1464 return ::simplifyShlInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 1465 } 1466 1467 /// Given operands for an LShr, see if we can fold the result. 1468 /// If not, this returns null. 1469 static Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, 1470 const SimplifyQuery &Q, unsigned MaxRecurse) { 1471 if (Value *V = simplifyRightShift(Instruction::LShr, Op0, Op1, IsExact, Q, 1472 MaxRecurse)) 1473 return V; 1474 1475 // (X << A) >> A -> X 1476 Value *X; 1477 if (Q.IIQ.UseInstrInfo && match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1)))) 1478 return X; 1479 1480 // ((X << A) | Y) >> A -> X if effective width of Y is not larger than A. 1481 // We can return X as we do in the above case since OR alters no bits in X. 1482 // SimplifyDemandedBits in InstCombine can do more general optimization for 1483 // bit manipulation. This pattern aims to provide opportunities for other 1484 // optimizers by supporting a simple but common case in InstSimplify. 1485 Value *Y; 1486 const APInt *ShRAmt, *ShLAmt; 1487 if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(ShRAmt)) && 1488 match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) && 1489 *ShRAmt == *ShLAmt) { 1490 const KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 1491 const unsigned EffWidthY = YKnown.countMaxActiveBits(); 1492 if (ShRAmt->uge(EffWidthY)) 1493 return X; 1494 } 1495 1496 return nullptr; 1497 } 1498 1499 Value *llvm::simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, 1500 const SimplifyQuery &Q) { 1501 return ::simplifyLShrInst(Op0, Op1, IsExact, Q, RecursionLimit); 1502 } 1503 1504 /// Given operands for an AShr, see if we can fold the result. 1505 /// If not, this returns null. 1506 static Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, 1507 const SimplifyQuery &Q, unsigned MaxRecurse) { 1508 if (Value *V = simplifyRightShift(Instruction::AShr, Op0, Op1, IsExact, Q, 1509 MaxRecurse)) 1510 return V; 1511 1512 // -1 >>a X --> -1 1513 // (-1 << X) a>> X --> -1 1514 // Do not return Op0 because it may contain undef elements if it's a vector. 1515 if (match(Op0, m_AllOnes()) || 1516 match(Op0, m_Shl(m_AllOnes(), m_Specific(Op1)))) 1517 return Constant::getAllOnesValue(Op0->getType()); 1518 1519 // (X << A) >> A -> X 1520 Value *X; 1521 if (Q.IIQ.UseInstrInfo && match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1)))) 1522 return X; 1523 1524 // Arithmetic shifting an all-sign-bit value is a no-op. 1525 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1526 if (NumSignBits == Op0->getType()->getScalarSizeInBits()) 1527 return Op0; 1528 1529 return nullptr; 1530 } 1531 1532 Value *llvm::simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, 1533 const SimplifyQuery &Q) { 1534 return ::simplifyAShrInst(Op0, Op1, IsExact, Q, RecursionLimit); 1535 } 1536 1537 /// Commuted variants are assumed to be handled by calling this function again 1538 /// with the parameters swapped. 1539 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp, 1540 ICmpInst *UnsignedICmp, bool IsAnd, 1541 const SimplifyQuery &Q) { 1542 Value *X, *Y; 1543 1544 ICmpInst::Predicate EqPred; 1545 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) || 1546 !ICmpInst::isEquality(EqPred)) 1547 return nullptr; 1548 1549 ICmpInst::Predicate UnsignedPred; 1550 1551 Value *A, *B; 1552 // Y = (A - B); 1553 if (match(Y, m_Sub(m_Value(A), m_Value(B)))) { 1554 if (match(UnsignedICmp, 1555 m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) && 1556 ICmpInst::isUnsigned(UnsignedPred)) { 1557 // A >=/<= B || (A - B) != 0 <--> true 1558 if ((UnsignedPred == ICmpInst::ICMP_UGE || 1559 UnsignedPred == ICmpInst::ICMP_ULE) && 1560 EqPred == ICmpInst::ICMP_NE && !IsAnd) 1561 return ConstantInt::getTrue(UnsignedICmp->getType()); 1562 // A </> B && (A - B) == 0 <--> false 1563 if ((UnsignedPred == ICmpInst::ICMP_ULT || 1564 UnsignedPred == ICmpInst::ICMP_UGT) && 1565 EqPred == ICmpInst::ICMP_EQ && IsAnd) 1566 return ConstantInt::getFalse(UnsignedICmp->getType()); 1567 1568 // A </> B && (A - B) != 0 <--> A </> B 1569 // A </> B || (A - B) != 0 <--> (A - B) != 0 1570 if (EqPred == ICmpInst::ICMP_NE && (UnsignedPred == ICmpInst::ICMP_ULT || 1571 UnsignedPred == ICmpInst::ICMP_UGT)) 1572 return IsAnd ? UnsignedICmp : ZeroICmp; 1573 1574 // A <=/>= B && (A - B) == 0 <--> (A - B) == 0 1575 // A <=/>= B || (A - B) == 0 <--> A <=/>= B 1576 if (EqPred == ICmpInst::ICMP_EQ && (UnsignedPred == ICmpInst::ICMP_ULE || 1577 UnsignedPred == ICmpInst::ICMP_UGE)) 1578 return IsAnd ? ZeroICmp : UnsignedICmp; 1579 } 1580 1581 // Given Y = (A - B) 1582 // Y >= A && Y != 0 --> Y >= A iff B != 0 1583 // Y < A || Y == 0 --> Y < A iff B != 0 1584 if (match(UnsignedICmp, 1585 m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) { 1586 if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd && 1587 EqPred == ICmpInst::ICMP_NE && 1588 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1589 return UnsignedICmp; 1590 if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd && 1591 EqPred == ICmpInst::ICMP_EQ && 1592 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1593 return UnsignedICmp; 1594 } 1595 } 1596 1597 if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) && 1598 ICmpInst::isUnsigned(UnsignedPred)) 1599 ; 1600 else if (match(UnsignedICmp, 1601 m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) && 1602 ICmpInst::isUnsigned(UnsignedPred)) 1603 UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); 1604 else 1605 return nullptr; 1606 1607 // X > Y && Y == 0 --> Y == 0 iff X != 0 1608 // X > Y || Y == 0 --> X > Y iff X != 0 1609 if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ && 1610 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1611 return IsAnd ? ZeroICmp : UnsignedICmp; 1612 1613 // X <= Y && Y != 0 --> X <= Y iff X != 0 1614 // X <= Y || Y != 0 --> Y != 0 iff X != 0 1615 if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE && 1616 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1617 return IsAnd ? UnsignedICmp : ZeroICmp; 1618 1619 // The transforms below here are expected to be handled more generally with 1620 // simplifyAndOrOfICmpsWithLimitConst() or in InstCombine's 1621 // foldAndOrOfICmpsWithConstEq(). If we are looking to trim optimizer overlap, 1622 // these are candidates for removal. 1623 1624 // X < Y && Y != 0 --> X < Y 1625 // X < Y || Y != 0 --> Y != 0 1626 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE) 1627 return IsAnd ? UnsignedICmp : ZeroICmp; 1628 1629 // X >= Y && Y == 0 --> Y == 0 1630 // X >= Y || Y == 0 --> X >= Y 1631 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ) 1632 return IsAnd ? ZeroICmp : UnsignedICmp; 1633 1634 // X < Y && Y == 0 --> false 1635 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ && 1636 IsAnd) 1637 return getFalse(UnsignedICmp->getType()); 1638 1639 // X >= Y || Y != 0 --> true 1640 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE && 1641 !IsAnd) 1642 return getTrue(UnsignedICmp->getType()); 1643 1644 return nullptr; 1645 } 1646 1647 /// Test if a pair of compares with a shared operand and 2 constants has an 1648 /// empty set intersection, full set union, or if one compare is a superset of 1649 /// the other. 1650 static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1, 1651 bool IsAnd) { 1652 // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)). 1653 if (Cmp0->getOperand(0) != Cmp1->getOperand(0)) 1654 return nullptr; 1655 1656 const APInt *C0, *C1; 1657 if (!match(Cmp0->getOperand(1), m_APInt(C0)) || 1658 !match(Cmp1->getOperand(1), m_APInt(C1))) 1659 return nullptr; 1660 1661 auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0); 1662 auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1); 1663 1664 // For and-of-compares, check if the intersection is empty: 1665 // (icmp X, C0) && (icmp X, C1) --> empty set --> false 1666 if (IsAnd && Range0.intersectWith(Range1).isEmptySet()) 1667 return getFalse(Cmp0->getType()); 1668 1669 // For or-of-compares, check if the union is full: 1670 // (icmp X, C0) || (icmp X, C1) --> full set --> true 1671 if (!IsAnd && Range0.unionWith(Range1).isFullSet()) 1672 return getTrue(Cmp0->getType()); 1673 1674 // Is one range a superset of the other? 1675 // If this is and-of-compares, take the smaller set: 1676 // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42 1677 // If this is or-of-compares, take the larger set: 1678 // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4 1679 if (Range0.contains(Range1)) 1680 return IsAnd ? Cmp1 : Cmp0; 1681 if (Range1.contains(Range0)) 1682 return IsAnd ? Cmp0 : Cmp1; 1683 1684 return nullptr; 1685 } 1686 1687 static Value *simplifyAndOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1688 const InstrInfoQuery &IIQ) { 1689 // (icmp (add V, C0), C1) & (icmp V, C0) 1690 ICmpInst::Predicate Pred0, Pred1; 1691 const APInt *C0, *C1; 1692 Value *V; 1693 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1694 return nullptr; 1695 1696 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1697 return nullptr; 1698 1699 auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0)); 1700 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1701 return nullptr; 1702 1703 Type *ITy = Op0->getType(); 1704 bool IsNSW = IIQ.hasNoSignedWrap(AddInst); 1705 bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst); 1706 1707 const APInt Delta = *C1 - *C0; 1708 if (C0->isStrictlyPositive()) { 1709 if (Delta == 2) { 1710 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT) 1711 return getFalse(ITy); 1712 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && IsNSW) 1713 return getFalse(ITy); 1714 } 1715 if (Delta == 1) { 1716 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT) 1717 return getFalse(ITy); 1718 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && IsNSW) 1719 return getFalse(ITy); 1720 } 1721 } 1722 if (C0->getBoolValue() && IsNUW) { 1723 if (Delta == 2) 1724 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT) 1725 return getFalse(ITy); 1726 if (Delta == 1) 1727 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT) 1728 return getFalse(ITy); 1729 } 1730 1731 return nullptr; 1732 } 1733 1734 /// Try to simplify and/or of icmp with ctpop intrinsic. 1735 static Value *simplifyAndOrOfICmpsWithCtpop(ICmpInst *Cmp0, ICmpInst *Cmp1, 1736 bool IsAnd) { 1737 ICmpInst::Predicate Pred0, Pred1; 1738 Value *X; 1739 const APInt *C; 1740 if (!match(Cmp0, m_ICmp(Pred0, m_Intrinsic<Intrinsic::ctpop>(m_Value(X)), 1741 m_APInt(C))) || 1742 !match(Cmp1, m_ICmp(Pred1, m_Specific(X), m_ZeroInt())) || C->isZero()) 1743 return nullptr; 1744 1745 // (ctpop(X) == C) || (X != 0) --> X != 0 where C > 0 1746 if (!IsAnd && Pred0 == ICmpInst::ICMP_EQ && Pred1 == ICmpInst::ICMP_NE) 1747 return Cmp1; 1748 // (ctpop(X) != C) && (X == 0) --> X == 0 where C > 0 1749 if (IsAnd && Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_EQ) 1750 return Cmp1; 1751 1752 return nullptr; 1753 } 1754 1755 static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1756 const SimplifyQuery &Q) { 1757 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true, Q)) 1758 return X; 1759 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true, Q)) 1760 return X; 1761 1762 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true)) 1763 return X; 1764 1765 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, true)) 1766 return X; 1767 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, true)) 1768 return X; 1769 1770 if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1771 return X; 1772 if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1773 return X; 1774 1775 return nullptr; 1776 } 1777 1778 static Value *simplifyOrOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1779 const InstrInfoQuery &IIQ) { 1780 // (icmp (add V, C0), C1) | (icmp V, C0) 1781 ICmpInst::Predicate Pred0, Pred1; 1782 const APInt *C0, *C1; 1783 Value *V; 1784 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1785 return nullptr; 1786 1787 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1788 return nullptr; 1789 1790 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0)); 1791 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1792 return nullptr; 1793 1794 Type *ITy = Op0->getType(); 1795 bool IsNSW = IIQ.hasNoSignedWrap(AddInst); 1796 bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst); 1797 1798 const APInt Delta = *C1 - *C0; 1799 if (C0->isStrictlyPositive()) { 1800 if (Delta == 2) { 1801 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE) 1802 return getTrue(ITy); 1803 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && IsNSW) 1804 return getTrue(ITy); 1805 } 1806 if (Delta == 1) { 1807 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE) 1808 return getTrue(ITy); 1809 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && IsNSW) 1810 return getTrue(ITy); 1811 } 1812 } 1813 if (C0->getBoolValue() && IsNUW) { 1814 if (Delta == 2) 1815 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE) 1816 return getTrue(ITy); 1817 if (Delta == 1) 1818 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE) 1819 return getTrue(ITy); 1820 } 1821 1822 return nullptr; 1823 } 1824 1825 static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1826 const SimplifyQuery &Q) { 1827 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false, Q)) 1828 return X; 1829 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false, Q)) 1830 return X; 1831 1832 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false)) 1833 return X; 1834 1835 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, false)) 1836 return X; 1837 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, false)) 1838 return X; 1839 1840 if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1841 return X; 1842 if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1843 return X; 1844 1845 return nullptr; 1846 } 1847 1848 static Value *simplifyAndOrOfFCmps(const SimplifyQuery &Q, FCmpInst *LHS, 1849 FCmpInst *RHS, bool IsAnd) { 1850 Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); 1851 Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); 1852 if (LHS0->getType() != RHS0->getType()) 1853 return nullptr; 1854 1855 const DataLayout &DL = Q.DL; 1856 const TargetLibraryInfo *TLI = Q.TLI; 1857 1858 FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); 1859 if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) || 1860 (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) { 1861 // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y 1862 // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X 1863 // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y 1864 // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X 1865 // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y 1866 // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X 1867 // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y 1868 // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X 1869 if (((LHS1 == RHS0 || LHS1 == RHS1) && 1870 isKnownNeverNaN(LHS0, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT)) || 1871 ((LHS0 == RHS0 || LHS0 == RHS1) && 1872 isKnownNeverNaN(LHS1, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT))) 1873 return RHS; 1874 1875 // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y 1876 // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X 1877 // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y 1878 // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X 1879 // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y 1880 // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X 1881 // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y 1882 // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X 1883 if (((RHS1 == LHS0 || RHS1 == LHS1) && 1884 isKnownNeverNaN(RHS0, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT)) || 1885 ((RHS0 == LHS0 || RHS0 == LHS1) && 1886 isKnownNeverNaN(RHS1, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT))) 1887 return LHS; 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 if (Value *Res = 1971 simplifyWithOpReplaced(Op1, A, B, Q, /* AllowRefinement */ true, 1972 /* DropFlags */ nullptr, MaxRecurse)) 1973 return Simplify(Res); 1974 if (Value *Res = 1975 simplifyWithOpReplaced(Op1, B, A, Q, /* AllowRefinement */ true, 1976 /* DropFlags */ nullptr, MaxRecurse)) 1977 return Simplify(Res); 1978 1979 return nullptr; 1980 } 1981 1982 /// Given a bitwise logic op, check if the operands are add/sub with a common 1983 /// source value and inverted constant (identity: C - X -> ~(X + ~C)). 1984 static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1, 1985 Instruction::BinaryOps Opcode) { 1986 assert(Op0->getType() == Op1->getType() && "Mismatched binop types"); 1987 assert(BinaryOperator::isBitwiseLogicOp(Opcode) && "Expected logic op"); 1988 Value *X; 1989 Constant *C1, *C2; 1990 if ((match(Op0, m_Add(m_Value(X), m_Constant(C1))) && 1991 match(Op1, m_Sub(m_Constant(C2), m_Specific(X)))) || 1992 (match(Op1, m_Add(m_Value(X), m_Constant(C1))) && 1993 match(Op0, m_Sub(m_Constant(C2), m_Specific(X))))) { 1994 if (ConstantExpr::getNot(C1) == C2) { 1995 // (X + C) & (~C - X) --> (X + C) & ~(X + C) --> 0 1996 // (X + C) | (~C - X) --> (X + C) | ~(X + C) --> -1 1997 // (X + C) ^ (~C - X) --> (X + C) ^ ~(X + C) --> -1 1998 Type *Ty = Op0->getType(); 1999 return Opcode == Instruction::And ? ConstantInt::getNullValue(Ty) 2000 : ConstantInt::getAllOnesValue(Ty); 2001 } 2002 } 2003 return nullptr; 2004 } 2005 2006 // Commutative patterns for and that will be tried with both operand orders. 2007 static Value *simplifyAndCommutative(Value *Op0, Value *Op1, 2008 const SimplifyQuery &Q, 2009 unsigned MaxRecurse) { 2010 // ~A & A = 0 2011 if (match(Op0, m_Not(m_Specific(Op1)))) 2012 return Constant::getNullValue(Op0->getType()); 2013 2014 // (A | ?) & A = A 2015 if (match(Op0, m_c_Or(m_Specific(Op1), m_Value()))) 2016 return Op1; 2017 2018 // (X | ~Y) & (X | Y) --> X 2019 Value *X, *Y; 2020 if (match(Op0, m_c_Or(m_Value(X), m_Not(m_Value(Y)))) && 2021 match(Op1, m_c_Or(m_Deferred(X), m_Deferred(Y)))) 2022 return X; 2023 2024 // If we have a multiplication overflow check that is being 'and'ed with a 2025 // check that one of the multipliers is not zero, we can omit the 'and', and 2026 // only keep the overflow check. 2027 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, true)) 2028 return Op1; 2029 2030 // -A & A = A if A is a power of two or zero. 2031 if (match(Op0, m_Neg(m_Specific(Op1))) && 2032 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2033 return Op1; 2034 2035 // This is a similar pattern used for checking if a value is a power-of-2: 2036 // (A - 1) & A --> 0 (if A is a power-of-2 or 0) 2037 if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) && 2038 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2039 return Constant::getNullValue(Op1->getType()); 2040 2041 // (x << N) & ((x << M) - 1) --> 0, where x is known to be a power of 2 and 2042 // M <= N. 2043 const APInt *Shift1, *Shift2; 2044 if (match(Op0, m_Shl(m_Value(X), m_APInt(Shift1))) && 2045 match(Op1, m_Add(m_Shl(m_Specific(X), m_APInt(Shift2)), m_AllOnes())) && 2046 isKnownToBeAPowerOfTwo(X, Q.DL, /*OrZero*/ true, /*Depth*/ 0, Q.AC, 2047 Q.CxtI) && 2048 Shift1->uge(*Shift2)) 2049 return Constant::getNullValue(Op0->getType()); 2050 2051 if (Value *V = 2052 simplifyAndOrWithICmpEq(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2053 return V; 2054 2055 return nullptr; 2056 } 2057 2058 /// Given operands for an And, see if we can fold the result. 2059 /// If not, this returns null. 2060 static Value *simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2061 unsigned MaxRecurse) { 2062 if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q)) 2063 return C; 2064 2065 // X & poison -> poison 2066 if (isa<PoisonValue>(Op1)) 2067 return Op1; 2068 2069 // X & undef -> 0 2070 if (Q.isUndefValue(Op1)) 2071 return Constant::getNullValue(Op0->getType()); 2072 2073 // X & X = X 2074 if (Op0 == Op1) 2075 return Op0; 2076 2077 // X & 0 = 0 2078 if (match(Op1, m_Zero())) 2079 return Constant::getNullValue(Op0->getType()); 2080 2081 // X & -1 = X 2082 if (match(Op1, m_AllOnes())) 2083 return Op0; 2084 2085 if (Value *Res = simplifyAndCommutative(Op0, Op1, Q, MaxRecurse)) 2086 return Res; 2087 if (Value *Res = simplifyAndCommutative(Op1, Op0, Q, MaxRecurse)) 2088 return Res; 2089 2090 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And)) 2091 return V; 2092 2093 // A mask that only clears known zeros of a shifted value is a no-op. 2094 const APInt *Mask; 2095 const APInt *ShAmt; 2096 Value *X, *Y; 2097 if (match(Op1, m_APInt(Mask))) { 2098 // If all bits in the inverted and shifted mask are clear: 2099 // and (shl X, ShAmt), Mask --> shl X, ShAmt 2100 if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) && 2101 (~(*Mask)).lshr(*ShAmt).isZero()) 2102 return Op0; 2103 2104 // If all bits in the inverted and shifted mask are clear: 2105 // and (lshr X, ShAmt), Mask --> lshr X, ShAmt 2106 if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) && 2107 (~(*Mask)).shl(*ShAmt).isZero()) 2108 return Op0; 2109 } 2110 2111 // and 2^x-1, 2^C --> 0 where x <= C. 2112 const APInt *PowerC; 2113 Value *Shift; 2114 if (match(Op1, m_Power2(PowerC)) && 2115 match(Op0, m_Add(m_Value(Shift), m_AllOnes())) && 2116 isKnownToBeAPowerOfTwo(Shift, Q.DL, /*OrZero*/ false, 0, Q.AC, Q.CxtI, 2117 Q.DT)) { 2118 KnownBits Known = computeKnownBits(Shift, /* Depth */ 0, Q); 2119 // Use getActiveBits() to make use of the additional power of two knowledge 2120 if (PowerC->getActiveBits() >= Known.getMaxValue().getActiveBits()) 2121 return ConstantInt::getNullValue(Op1->getType()); 2122 } 2123 2124 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true)) 2125 return V; 2126 2127 // Try some generic simplifications for associative operations. 2128 if (Value *V = 2129 simplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2130 return V; 2131 2132 // And distributes over Or. Try some generic simplifications based on this. 2133 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2134 Instruction::Or, Q, MaxRecurse)) 2135 return V; 2136 2137 // And distributes over Xor. Try some generic simplifications based on this. 2138 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2139 Instruction::Xor, Q, MaxRecurse)) 2140 return V; 2141 2142 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2143 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2144 // A & (A && B) -> A && B 2145 if (match(Op1, m_Select(m_Specific(Op0), m_Value(), m_Zero()))) 2146 return Op1; 2147 else if (match(Op0, m_Select(m_Specific(Op1), m_Value(), m_Zero()))) 2148 return Op0; 2149 } 2150 // If the operation is with the result of a select instruction, check 2151 // whether operating on either branch of the select always yields the same 2152 // value. 2153 if (Value *V = 2154 threadBinOpOverSelect(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2155 return V; 2156 } 2157 2158 // If the operation is with the result of a phi instruction, check whether 2159 // operating on all incoming values of the phi always yields the same value. 2160 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2161 if (Value *V = 2162 threadBinOpOverPHI(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2163 return V; 2164 2165 // Assuming the effective width of Y is not larger than A, i.e. all bits 2166 // from X and Y are disjoint in (X << A) | Y, 2167 // if the mask of this AND op covers all bits of X or Y, while it covers 2168 // no bits from the other, we can bypass this AND op. E.g., 2169 // ((X << A) | Y) & Mask -> Y, 2170 // if Mask = ((1 << effective_width_of(Y)) - 1) 2171 // ((X << A) | Y) & Mask -> X << A, 2172 // if Mask = ((1 << effective_width_of(X)) - 1) << A 2173 // SimplifyDemandedBits in InstCombine can optimize the general case. 2174 // This pattern aims to help other passes for a common case. 2175 Value *XShifted; 2176 if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(Mask)) && 2177 match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)), 2178 m_Value(XShifted)), 2179 m_Value(Y)))) { 2180 const unsigned Width = Op0->getType()->getScalarSizeInBits(); 2181 const unsigned ShftCnt = ShAmt->getLimitedValue(Width); 2182 const KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 2183 const unsigned EffWidthY = YKnown.countMaxActiveBits(); 2184 if (EffWidthY <= ShftCnt) { 2185 const KnownBits XKnown = computeKnownBits(X, /* Depth */ 0, Q); 2186 const unsigned EffWidthX = XKnown.countMaxActiveBits(); 2187 const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY); 2188 const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt; 2189 // If the mask is extracting all bits from X or Y as is, we can skip 2190 // this AND op. 2191 if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask)) 2192 return Y; 2193 if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask)) 2194 return XShifted; 2195 } 2196 } 2197 2198 // ((X | Y) ^ X ) & ((X | Y) ^ Y) --> 0 2199 // ((X | Y) ^ Y ) & ((X | Y) ^ X) --> 0 2200 BinaryOperator *Or; 2201 if (match(Op0, m_c_Xor(m_Value(X), 2202 m_CombineAnd(m_BinOp(Or), 2203 m_c_Or(m_Deferred(X), m_Value(Y))))) && 2204 match(Op1, m_c_Xor(m_Specific(Or), m_Specific(Y)))) 2205 return Constant::getNullValue(Op0->getType()); 2206 2207 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2208 if (std::optional<bool> Implied = isImpliedCondition(Op0, Op1, Q.DL)) { 2209 // If Op0 is true implies Op1 is true, then Op0 is a subset of Op1. 2210 if (*Implied == true) 2211 return Op0; 2212 // If Op0 is true implies Op1 is false, then they are not true together. 2213 if (*Implied == false) 2214 return ConstantInt::getFalse(Op0->getType()); 2215 } 2216 if (std::optional<bool> Implied = isImpliedCondition(Op1, Op0, Q.DL)) { 2217 // If Op1 is true implies Op0 is true, then Op1 is a subset of Op0. 2218 if (*Implied) 2219 return Op1; 2220 // If Op1 is true implies Op0 is false, then they are not true together. 2221 if (!*Implied) 2222 return ConstantInt::getFalse(Op1->getType()); 2223 } 2224 } 2225 2226 if (Value *V = simplifyByDomEq(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2227 return V; 2228 2229 return nullptr; 2230 } 2231 2232 Value *llvm::simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2233 return ::simplifyAndInst(Op0, Op1, Q, RecursionLimit); 2234 } 2235 2236 // TODO: Many of these folds could use LogicalAnd/LogicalOr. 2237 static Value *simplifyOrLogic(Value *X, Value *Y) { 2238 assert(X->getType() == Y->getType() && "Expected same type for 'or' ops"); 2239 Type *Ty = X->getType(); 2240 2241 // X | ~X --> -1 2242 if (match(Y, m_Not(m_Specific(X)))) 2243 return ConstantInt::getAllOnesValue(Ty); 2244 2245 // X | ~(X & ?) = -1 2246 if (match(Y, m_Not(m_c_And(m_Specific(X), m_Value())))) 2247 return ConstantInt::getAllOnesValue(Ty); 2248 2249 // X | (X & ?) --> X 2250 if (match(Y, m_c_And(m_Specific(X), m_Value()))) 2251 return X; 2252 2253 Value *A, *B; 2254 2255 // (A ^ B) | (A | B) --> A | B 2256 // (A ^ B) | (B | A) --> B | A 2257 if (match(X, m_Xor(m_Value(A), m_Value(B))) && 2258 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2259 return Y; 2260 2261 // ~(A ^ B) | (A | B) --> -1 2262 // ~(A ^ B) | (B | A) --> -1 2263 if (match(X, m_Not(m_Xor(m_Value(A), m_Value(B)))) && 2264 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2265 return ConstantInt::getAllOnesValue(Ty); 2266 2267 // (A & ~B) | (A ^ B) --> A ^ B 2268 // (~B & A) | (A ^ B) --> A ^ B 2269 // (A & ~B) | (B ^ A) --> B ^ A 2270 // (~B & A) | (B ^ A) --> B ^ A 2271 if (match(X, m_c_And(m_Value(A), m_Not(m_Value(B)))) && 2272 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2273 return Y; 2274 2275 // (~A ^ B) | (A & B) --> ~A ^ B 2276 // (B ^ ~A) | (A & B) --> B ^ ~A 2277 // (~A ^ B) | (B & A) --> ~A ^ B 2278 // (B ^ ~A) | (B & A) --> B ^ ~A 2279 if (match(X, m_c_Xor(m_NotForbidUndef(m_Value(A)), m_Value(B))) && 2280 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2281 return X; 2282 2283 // (~A | B) | (A ^ B) --> -1 2284 // (~A | B) | (B ^ A) --> -1 2285 // (B | ~A) | (A ^ B) --> -1 2286 // (B | ~A) | (B ^ A) --> -1 2287 if (match(X, m_c_Or(m_Not(m_Value(A)), m_Value(B))) && 2288 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2289 return ConstantInt::getAllOnesValue(Ty); 2290 2291 // (~A & B) | ~(A | B) --> ~A 2292 // (~A & B) | ~(B | A) --> ~A 2293 // (B & ~A) | ~(A | B) --> ~A 2294 // (B & ~A) | ~(B | A) --> ~A 2295 Value *NotA; 2296 if (match(X, 2297 m_c_And(m_CombineAnd(m_Value(NotA), m_NotForbidUndef(m_Value(A))), 2298 m_Value(B))) && 2299 match(Y, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) 2300 return NotA; 2301 // The same is true of Logical And 2302 // TODO: This could share the logic of the version above if there was a 2303 // version of LogicalAnd that allowed more than just i1 types. 2304 if (match(X, m_c_LogicalAnd( 2305 m_CombineAnd(m_Value(NotA), m_NotForbidUndef(m_Value(A))), 2306 m_Value(B))) && 2307 match(Y, m_Not(m_c_LogicalOr(m_Specific(A), m_Specific(B))))) 2308 return NotA; 2309 2310 // ~(A ^ B) | (A & B) --> ~(A ^ B) 2311 // ~(A ^ B) | (B & A) --> ~(A ^ B) 2312 Value *NotAB; 2313 if (match(X, m_CombineAnd(m_NotForbidUndef(m_Xor(m_Value(A), m_Value(B))), 2314 m_Value(NotAB))) && 2315 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2316 return NotAB; 2317 2318 // ~(A & B) | (A ^ B) --> ~(A & B) 2319 // ~(A & B) | (B ^ A) --> ~(A & B) 2320 if (match(X, m_CombineAnd(m_NotForbidUndef(m_And(m_Value(A), m_Value(B))), 2321 m_Value(NotAB))) && 2322 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2323 return NotAB; 2324 2325 return nullptr; 2326 } 2327 2328 /// Given operands for an Or, see if we can fold the result. 2329 /// If not, this returns null. 2330 static Value *simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2331 unsigned MaxRecurse) { 2332 if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q)) 2333 return C; 2334 2335 // X | poison -> poison 2336 if (isa<PoisonValue>(Op1)) 2337 return Op1; 2338 2339 // X | undef -> -1 2340 // X | -1 = -1 2341 // Do not return Op1 because it may contain undef elements if it's a vector. 2342 if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes())) 2343 return Constant::getAllOnesValue(Op0->getType()); 2344 2345 // X | X = X 2346 // X | 0 = X 2347 if (Op0 == Op1 || match(Op1, m_Zero())) 2348 return Op0; 2349 2350 if (Value *R = simplifyOrLogic(Op0, Op1)) 2351 return R; 2352 if (Value *R = simplifyOrLogic(Op1, Op0)) 2353 return R; 2354 2355 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Or)) 2356 return V; 2357 2358 // Rotated -1 is still -1: 2359 // (-1 << X) | (-1 >> (C - X)) --> -1 2360 // (-1 >> X) | (-1 << (C - X)) --> -1 2361 // ...with C <= bitwidth (and commuted variants). 2362 Value *X, *Y; 2363 if ((match(Op0, m_Shl(m_AllOnes(), m_Value(X))) && 2364 match(Op1, m_LShr(m_AllOnes(), m_Value(Y)))) || 2365 (match(Op1, m_Shl(m_AllOnes(), m_Value(X))) && 2366 match(Op0, m_LShr(m_AllOnes(), m_Value(Y))))) { 2367 const APInt *C; 2368 if ((match(X, m_Sub(m_APInt(C), m_Specific(Y))) || 2369 match(Y, m_Sub(m_APInt(C), m_Specific(X)))) && 2370 C->ule(X->getType()->getScalarSizeInBits())) { 2371 return ConstantInt::getAllOnesValue(X->getType()); 2372 } 2373 } 2374 2375 // A funnel shift (rotate) can be decomposed into simpler shifts. See if we 2376 // are mixing in another shift that is redundant with the funnel shift. 2377 2378 // (fshl X, ?, Y) | (shl X, Y) --> fshl X, ?, Y 2379 // (shl X, Y) | (fshl X, ?, Y) --> fshl X, ?, Y 2380 if (match(Op0, 2381 m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) && 2382 match(Op1, m_Shl(m_Specific(X), m_Specific(Y)))) 2383 return Op0; 2384 if (match(Op1, 2385 m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) && 2386 match(Op0, m_Shl(m_Specific(X), m_Specific(Y)))) 2387 return Op1; 2388 2389 // (fshr ?, X, Y) | (lshr X, Y) --> fshr ?, X, Y 2390 // (lshr X, Y) | (fshr ?, X, Y) --> fshr ?, X, Y 2391 if (match(Op0, 2392 m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) && 2393 match(Op1, m_LShr(m_Specific(X), m_Specific(Y)))) 2394 return Op0; 2395 if (match(Op1, 2396 m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) && 2397 match(Op0, m_LShr(m_Specific(X), m_Specific(Y)))) 2398 return Op1; 2399 2400 if (Value *V = 2401 simplifyAndOrWithICmpEq(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2402 return V; 2403 if (Value *V = 2404 simplifyAndOrWithICmpEq(Instruction::Or, Op1, Op0, Q, MaxRecurse)) 2405 return V; 2406 2407 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false)) 2408 return V; 2409 2410 // If we have a multiplication overflow check that is being 'and'ed with a 2411 // check that one of the multipliers is not zero, we can omit the 'and', and 2412 // only keep the overflow check. 2413 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, false)) 2414 return Op1; 2415 if (isCheckForZeroAndMulWithOverflow(Op1, Op0, false)) 2416 return Op0; 2417 2418 // Try some generic simplifications for associative operations. 2419 if (Value *V = 2420 simplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2421 return V; 2422 2423 // Or distributes over And. Try some generic simplifications based on this. 2424 if (Value *V = expandCommutativeBinOp(Instruction::Or, Op0, Op1, 2425 Instruction::And, Q, MaxRecurse)) 2426 return V; 2427 2428 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2429 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2430 // A | (A || B) -> A || B 2431 if (match(Op1, m_Select(m_Specific(Op0), m_One(), m_Value()))) 2432 return Op1; 2433 else if (match(Op0, m_Select(m_Specific(Op1), m_One(), m_Value()))) 2434 return Op0; 2435 } 2436 // If the operation is with the result of a select instruction, check 2437 // whether operating on either branch of the select always yields the same 2438 // value. 2439 if (Value *V = 2440 threadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2441 return V; 2442 } 2443 2444 // (A & C1)|(B & C2) 2445 Value *A, *B; 2446 const APInt *C1, *C2; 2447 if (match(Op0, m_And(m_Value(A), m_APInt(C1))) && 2448 match(Op1, m_And(m_Value(B), m_APInt(C2)))) { 2449 if (*C1 == ~*C2) { 2450 // (A & C1)|(B & C2) 2451 // If we have: ((V + N) & C1) | (V & C2) 2452 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 2453 // replace with V+N. 2454 Value *N; 2455 if (C2->isMask() && // C2 == 0+1+ 2456 match(A, m_c_Add(m_Specific(B), m_Value(N)))) { 2457 // Add commutes, try both ways. 2458 if (MaskedValueIsZero(N, *C2, Q)) 2459 return A; 2460 } 2461 // Or commutes, try both ways. 2462 if (C1->isMask() && match(B, m_c_Add(m_Specific(A), m_Value(N)))) { 2463 // Add commutes, try both ways. 2464 if (MaskedValueIsZero(N, *C1, Q)) 2465 return B; 2466 } 2467 } 2468 } 2469 2470 // If the operation is with the result of a phi instruction, check whether 2471 // operating on all incoming values of the phi always yields the same value. 2472 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2473 if (Value *V = threadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2474 return V; 2475 2476 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2477 if (std::optional<bool> Implied = 2478 isImpliedCondition(Op0, Op1, Q.DL, false)) { 2479 // If Op0 is false implies Op1 is false, then Op1 is a subset of Op0. 2480 if (*Implied == false) 2481 return Op0; 2482 // If Op0 is false implies Op1 is true, then at least one is always true. 2483 if (*Implied == true) 2484 return ConstantInt::getTrue(Op0->getType()); 2485 } 2486 if (std::optional<bool> Implied = 2487 isImpliedCondition(Op1, Op0, Q.DL, false)) { 2488 // If Op1 is false implies Op0 is false, then Op0 is a subset of Op1. 2489 if (*Implied == false) 2490 return Op1; 2491 // If Op1 is false implies Op0 is true, then at least one is always true. 2492 if (*Implied == true) 2493 return ConstantInt::getTrue(Op1->getType()); 2494 } 2495 } 2496 2497 if (Value *V = simplifyByDomEq(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2498 return V; 2499 2500 return nullptr; 2501 } 2502 2503 Value *llvm::simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2504 return ::simplifyOrInst(Op0, Op1, Q, RecursionLimit); 2505 } 2506 2507 /// Given operands for a Xor, see if we can fold the result. 2508 /// If not, this returns null. 2509 static Value *simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2510 unsigned MaxRecurse) { 2511 if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q)) 2512 return C; 2513 2514 // X ^ poison -> poison 2515 if (isa<PoisonValue>(Op1)) 2516 return Op1; 2517 2518 // A ^ undef -> undef 2519 if (Q.isUndefValue(Op1)) 2520 return Op1; 2521 2522 // A ^ 0 = A 2523 if (match(Op1, m_Zero())) 2524 return Op0; 2525 2526 // A ^ A = 0 2527 if (Op0 == Op1) 2528 return Constant::getNullValue(Op0->getType()); 2529 2530 // A ^ ~A = ~A ^ A = -1 2531 if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0)))) 2532 return Constant::getAllOnesValue(Op0->getType()); 2533 2534 auto foldAndOrNot = [](Value *X, Value *Y) -> Value * { 2535 Value *A, *B; 2536 // (~A & B) ^ (A | B) --> A -- There are 8 commuted variants. 2537 if (match(X, m_c_And(m_Not(m_Value(A)), m_Value(B))) && 2538 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2539 return A; 2540 2541 // (~A | B) ^ (A & B) --> ~A -- There are 8 commuted variants. 2542 // The 'not' op must contain a complete -1 operand (no undef elements for 2543 // vector) for the transform to be safe. 2544 Value *NotA; 2545 if (match(X, 2546 m_c_Or(m_CombineAnd(m_NotForbidUndef(m_Value(A)), m_Value(NotA)), 2547 m_Value(B))) && 2548 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2549 return NotA; 2550 2551 return nullptr; 2552 }; 2553 if (Value *R = foldAndOrNot(Op0, Op1)) 2554 return R; 2555 if (Value *R = foldAndOrNot(Op1, Op0)) 2556 return R; 2557 2558 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor)) 2559 return V; 2560 2561 // Try some generic simplifications for associative operations. 2562 if (Value *V = 2563 simplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, MaxRecurse)) 2564 return V; 2565 2566 // Threading Xor over selects and phi nodes is pointless, so don't bother. 2567 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 2568 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 2569 // only if B and C are equal. If B and C are equal then (since we assume 2570 // that operands have already been simplified) "select(cond, B, C)" should 2571 // have been simplified to the common value of B and C already. Analysing 2572 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 2573 // for threading over phi nodes. 2574 2575 if (Value *V = simplifyByDomEq(Instruction::Xor, Op0, Op1, Q, MaxRecurse)) 2576 return V; 2577 2578 return nullptr; 2579 } 2580 2581 Value *llvm::simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2582 return ::simplifyXorInst(Op0, Op1, Q, RecursionLimit); 2583 } 2584 2585 static Type *getCompareTy(Value *Op) { 2586 return CmpInst::makeCmpResultType(Op->getType()); 2587 } 2588 2589 /// Rummage around inside V looking for something equivalent to the comparison 2590 /// "LHS Pred RHS". Return such a value if found, otherwise return null. 2591 /// Helper function for analyzing max/min idioms. 2592 static Value *extractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 2593 Value *LHS, Value *RHS) { 2594 SelectInst *SI = dyn_cast<SelectInst>(V); 2595 if (!SI) 2596 return nullptr; 2597 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 2598 if (!Cmp) 2599 return nullptr; 2600 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 2601 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 2602 return Cmp; 2603 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 2604 LHS == CmpRHS && RHS == CmpLHS) 2605 return Cmp; 2606 return nullptr; 2607 } 2608 2609 /// Return true if the underlying object (storage) must be disjoint from 2610 /// storage returned by any noalias return call. 2611 static bool isAllocDisjoint(const Value *V) { 2612 // For allocas, we consider only static ones (dynamic 2613 // allocas might be transformed into calls to malloc not simultaneously 2614 // live with the compared-to allocation). For globals, we exclude symbols 2615 // that might be resolve lazily to symbols in another dynamically-loaded 2616 // library (and, thus, could be malloc'ed by the implementation). 2617 if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) 2618 return AI->isStaticAlloca(); 2619 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) 2620 return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() || 2621 GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) && 2622 !GV->isThreadLocal(); 2623 if (const Argument *A = dyn_cast<Argument>(V)) 2624 return A->hasByValAttr(); 2625 return false; 2626 } 2627 2628 /// Return true if V1 and V2 are each the base of some distict storage region 2629 /// [V, object_size(V)] which do not overlap. Note that zero sized regions 2630 /// *are* possible, and that zero sized regions do not overlap with any other. 2631 static bool haveNonOverlappingStorage(const Value *V1, const Value *V2) { 2632 // Global variables always exist, so they always exist during the lifetime 2633 // of each other and all allocas. Global variables themselves usually have 2634 // non-overlapping storage, but since their addresses are constants, the 2635 // case involving two globals does not reach here and is instead handled in 2636 // constant folding. 2637 // 2638 // Two different allocas usually have different addresses... 2639 // 2640 // However, if there's an @llvm.stackrestore dynamically in between two 2641 // allocas, they may have the same address. It's tempting to reduce the 2642 // scope of the problem by only looking at *static* allocas here. That would 2643 // cover the majority of allocas while significantly reducing the likelihood 2644 // of having an @llvm.stackrestore pop up in the middle. However, it's not 2645 // actually impossible for an @llvm.stackrestore to pop up in the middle of 2646 // an entry block. Also, if we have a block that's not attached to a 2647 // function, we can't tell if it's "static" under the current definition. 2648 // Theoretically, this problem could be fixed by creating a new kind of 2649 // instruction kind specifically for static allocas. Such a new instruction 2650 // could be required to be at the top of the entry block, thus preventing it 2651 // from being subject to a @llvm.stackrestore. Instcombine could even 2652 // convert regular allocas into these special allocas. It'd be nifty. 2653 // However, until then, this problem remains open. 2654 // 2655 // So, we'll assume that two non-empty allocas have different addresses 2656 // for now. 2657 auto isByValArg = [](const Value *V) { 2658 const Argument *A = dyn_cast<Argument>(V); 2659 return A && A->hasByValAttr(); 2660 }; 2661 2662 // Byval args are backed by store which does not overlap with each other, 2663 // allocas, or globals. 2664 if (isByValArg(V1)) 2665 return isa<AllocaInst>(V2) || isa<GlobalVariable>(V2) || isByValArg(V2); 2666 if (isByValArg(V2)) 2667 return isa<AllocaInst>(V1) || isa<GlobalVariable>(V1) || isByValArg(V1); 2668 2669 return isa<AllocaInst>(V1) && 2670 (isa<AllocaInst>(V2) || isa<GlobalVariable>(V2)); 2671 } 2672 2673 // A significant optimization not implemented here is assuming that alloca 2674 // addresses are not equal to incoming argument values. They don't *alias*, 2675 // as we say, but that doesn't mean they aren't equal, so we take a 2676 // conservative approach. 2677 // 2678 // This is inspired in part by C++11 5.10p1: 2679 // "Two pointers of the same type compare equal if and only if they are both 2680 // null, both point to the same function, or both represent the same 2681 // address." 2682 // 2683 // This is pretty permissive. 2684 // 2685 // It's also partly due to C11 6.5.9p6: 2686 // "Two pointers compare equal if and only if both are null pointers, both are 2687 // pointers to the same object (including a pointer to an object and a 2688 // subobject at its beginning) or function, both are pointers to one past the 2689 // last element of the same array object, or one is a pointer to one past the 2690 // end of one array object and the other is a pointer to the start of a 2691 // different array object that happens to immediately follow the first array 2692 // object in the address space.) 2693 // 2694 // C11's version is more restrictive, however there's no reason why an argument 2695 // couldn't be a one-past-the-end value for a stack object in the caller and be 2696 // equal to the beginning of a stack object in the callee. 2697 // 2698 // If the C and C++ standards are ever made sufficiently restrictive in this 2699 // area, it may be possible to update LLVM's semantics accordingly and reinstate 2700 // this optimization. 2701 static Constant *computePointerICmp(CmpInst::Predicate Pred, Value *LHS, 2702 Value *RHS, const SimplifyQuery &Q) { 2703 assert(LHS->getType() == RHS->getType() && "Must have same types"); 2704 const DataLayout &DL = Q.DL; 2705 const TargetLibraryInfo *TLI = Q.TLI; 2706 const DominatorTree *DT = Q.DT; 2707 const Instruction *CxtI = Q.CxtI; 2708 2709 // We can only fold certain predicates on pointer comparisons. 2710 switch (Pred) { 2711 default: 2712 return nullptr; 2713 2714 // Equality comparisons are easy to fold. 2715 case CmpInst::ICMP_EQ: 2716 case CmpInst::ICMP_NE: 2717 break; 2718 2719 // We can only handle unsigned relational comparisons because 'inbounds' on 2720 // a GEP only protects against unsigned wrapping. 2721 case CmpInst::ICMP_UGT: 2722 case CmpInst::ICMP_UGE: 2723 case CmpInst::ICMP_ULT: 2724 case CmpInst::ICMP_ULE: 2725 // However, we have to switch them to their signed variants to handle 2726 // negative indices from the base pointer. 2727 Pred = ICmpInst::getSignedPredicate(Pred); 2728 break; 2729 } 2730 2731 // Strip off any constant offsets so that we can reason about them. 2732 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets 2733 // here and compare base addresses like AliasAnalysis does, however there are 2734 // numerous hazards. AliasAnalysis and its utilities rely on special rules 2735 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis 2736 // doesn't need to guarantee pointer inequality when it says NoAlias. 2737 2738 // Even if an non-inbounds GEP occurs along the path we can still optimize 2739 // equality comparisons concerning the result. 2740 bool AllowNonInbounds = ICmpInst::isEquality(Pred); 2741 unsigned IndexSize = DL.getIndexTypeSizeInBits(LHS->getType()); 2742 APInt LHSOffset(IndexSize, 0), RHSOffset(IndexSize, 0); 2743 LHS = LHS->stripAndAccumulateConstantOffsets(DL, LHSOffset, AllowNonInbounds); 2744 RHS = RHS->stripAndAccumulateConstantOffsets(DL, RHSOffset, AllowNonInbounds); 2745 2746 // If LHS and RHS are related via constant offsets to the same base 2747 // value, we can replace it with an icmp which just compares the offsets. 2748 if (LHS == RHS) 2749 return ConstantInt::get(getCompareTy(LHS), 2750 ICmpInst::compare(LHSOffset, RHSOffset, Pred)); 2751 2752 // Various optimizations for (in)equality comparisons. 2753 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) { 2754 // Different non-empty allocations that exist at the same time have 2755 // different addresses (if the program can tell). If the offsets are 2756 // within the bounds of their allocations (and not one-past-the-end! 2757 // so we can't use inbounds!), and their allocations aren't the same, 2758 // the pointers are not equal. 2759 if (haveNonOverlappingStorage(LHS, RHS)) { 2760 uint64_t LHSSize, RHSSize; 2761 ObjectSizeOpts Opts; 2762 Opts.EvalMode = ObjectSizeOpts::Mode::Min; 2763 auto *F = [](Value *V) -> Function * { 2764 if (auto *I = dyn_cast<Instruction>(V)) 2765 return I->getFunction(); 2766 if (auto *A = dyn_cast<Argument>(V)) 2767 return A->getParent(); 2768 return nullptr; 2769 }(LHS); 2770 Opts.NullIsUnknownSize = F ? NullPointerIsDefined(F) : true; 2771 if (getObjectSize(LHS, LHSSize, DL, TLI, Opts) && 2772 getObjectSize(RHS, RHSSize, DL, TLI, Opts)) { 2773 APInt Dist = LHSOffset - RHSOffset; 2774 if (Dist.isNonNegative() ? Dist.ult(LHSSize) : (-Dist).ult(RHSSize)) 2775 return ConstantInt::get(getCompareTy(LHS), 2776 !CmpInst::isTrueWhenEqual(Pred)); 2777 } 2778 } 2779 2780 // If one side of the equality comparison must come from a noalias call 2781 // (meaning a system memory allocation function), and the other side must 2782 // come from a pointer that cannot overlap with dynamically-allocated 2783 // memory within the lifetime of the current function (allocas, byval 2784 // arguments, globals), then determine the comparison result here. 2785 SmallVector<const Value *, 8> LHSUObjs, RHSUObjs; 2786 getUnderlyingObjects(LHS, LHSUObjs); 2787 getUnderlyingObjects(RHS, RHSUObjs); 2788 2789 // Is the set of underlying objects all noalias calls? 2790 auto IsNAC = [](ArrayRef<const Value *> Objects) { 2791 return all_of(Objects, isNoAliasCall); 2792 }; 2793 2794 // Is the set of underlying objects all things which must be disjoint from 2795 // noalias calls. We assume that indexing from such disjoint storage 2796 // into the heap is undefined, and thus offsets can be safely ignored. 2797 auto IsAllocDisjoint = [](ArrayRef<const Value *> Objects) { 2798 return all_of(Objects, ::isAllocDisjoint); 2799 }; 2800 2801 if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) || 2802 (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs))) 2803 return ConstantInt::get(getCompareTy(LHS), 2804 !CmpInst::isTrueWhenEqual(Pred)); 2805 2806 // Fold comparisons for non-escaping pointer even if the allocation call 2807 // cannot be elided. We cannot fold malloc comparison to null. Also, the 2808 // dynamic allocation call could be either of the operands. Note that 2809 // the other operand can not be based on the alloc - if it were, then 2810 // the cmp itself would be a capture. 2811 Value *MI = nullptr; 2812 if (isAllocLikeFn(LHS, TLI) && 2813 llvm::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT)) 2814 MI = LHS; 2815 else if (isAllocLikeFn(RHS, TLI) && 2816 llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT)) 2817 MI = RHS; 2818 if (MI) { 2819 // FIXME: This is incorrect, see PR54002. While we can assume that the 2820 // allocation is at an address that makes the comparison false, this 2821 // requires that *all* comparisons to that address be false, which 2822 // InstSimplify cannot guarantee. 2823 struct CustomCaptureTracker : public CaptureTracker { 2824 bool Captured = false; 2825 void tooManyUses() override { Captured = true; } 2826 bool captured(const Use *U) override { 2827 if (auto *ICmp = dyn_cast<ICmpInst>(U->getUser())) { 2828 // Comparison against value stored in global variable. Given the 2829 // pointer does not escape, its value cannot be guessed and stored 2830 // separately in a global variable. 2831 unsigned OtherIdx = 1 - U->getOperandNo(); 2832 auto *LI = dyn_cast<LoadInst>(ICmp->getOperand(OtherIdx)); 2833 if (LI && isa<GlobalVariable>(LI->getPointerOperand())) 2834 return false; 2835 } 2836 2837 Captured = true; 2838 return true; 2839 } 2840 }; 2841 CustomCaptureTracker Tracker; 2842 PointerMayBeCaptured(MI, &Tracker); 2843 if (!Tracker.Captured) 2844 return ConstantInt::get(getCompareTy(LHS), 2845 CmpInst::isFalseWhenEqual(Pred)); 2846 } 2847 } 2848 2849 // Otherwise, fail. 2850 return nullptr; 2851 } 2852 2853 /// Fold an icmp when its operands have i1 scalar type. 2854 static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS, 2855 Value *RHS, const SimplifyQuery &Q) { 2856 Type *ITy = getCompareTy(LHS); // The return type. 2857 Type *OpTy = LHS->getType(); // The operand type. 2858 if (!OpTy->isIntOrIntVectorTy(1)) 2859 return nullptr; 2860 2861 // A boolean compared to true/false can be reduced in 14 out of the 20 2862 // (10 predicates * 2 constants) possible combinations. The other 2863 // 6 cases require a 'not' of the LHS. 2864 2865 auto ExtractNotLHS = [](Value *V) -> Value * { 2866 Value *X; 2867 if (match(V, m_Not(m_Value(X)))) 2868 return X; 2869 return nullptr; 2870 }; 2871 2872 if (match(RHS, m_Zero())) { 2873 switch (Pred) { 2874 case CmpInst::ICMP_NE: // X != 0 -> X 2875 case CmpInst::ICMP_UGT: // X >u 0 -> X 2876 case CmpInst::ICMP_SLT: // X <s 0 -> X 2877 return LHS; 2878 2879 case CmpInst::ICMP_EQ: // not(X) == 0 -> X != 0 -> X 2880 case CmpInst::ICMP_ULE: // not(X) <=u 0 -> X >u 0 -> X 2881 case CmpInst::ICMP_SGE: // not(X) >=s 0 -> X <s 0 -> X 2882 if (Value *X = ExtractNotLHS(LHS)) 2883 return X; 2884 break; 2885 2886 case CmpInst::ICMP_ULT: // X <u 0 -> false 2887 case CmpInst::ICMP_SGT: // X >s 0 -> false 2888 return getFalse(ITy); 2889 2890 case CmpInst::ICMP_UGE: // X >=u 0 -> true 2891 case CmpInst::ICMP_SLE: // X <=s 0 -> true 2892 return getTrue(ITy); 2893 2894 default: 2895 break; 2896 } 2897 } else if (match(RHS, m_One())) { 2898 switch (Pred) { 2899 case CmpInst::ICMP_EQ: // X == 1 -> X 2900 case CmpInst::ICMP_UGE: // X >=u 1 -> X 2901 case CmpInst::ICMP_SLE: // X <=s -1 -> X 2902 return LHS; 2903 2904 case CmpInst::ICMP_NE: // not(X) != 1 -> X == 1 -> X 2905 case CmpInst::ICMP_ULT: // not(X) <=u 1 -> X >=u 1 -> X 2906 case CmpInst::ICMP_SGT: // not(X) >s 1 -> X <=s -1 -> X 2907 if (Value *X = ExtractNotLHS(LHS)) 2908 return X; 2909 break; 2910 2911 case CmpInst::ICMP_UGT: // X >u 1 -> false 2912 case CmpInst::ICMP_SLT: // X <s -1 -> false 2913 return getFalse(ITy); 2914 2915 case CmpInst::ICMP_ULE: // X <=u 1 -> true 2916 case CmpInst::ICMP_SGE: // X >=s -1 -> true 2917 return getTrue(ITy); 2918 2919 default: 2920 break; 2921 } 2922 } 2923 2924 switch (Pred) { 2925 default: 2926 break; 2927 case ICmpInst::ICMP_UGE: 2928 if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false)) 2929 return getTrue(ITy); 2930 break; 2931 case ICmpInst::ICMP_SGE: 2932 /// For signed comparison, the values for an i1 are 0 and -1 2933 /// respectively. This maps into a truth table of: 2934 /// LHS | RHS | LHS >=s RHS | LHS implies RHS 2935 /// 0 | 0 | 1 (0 >= 0) | 1 2936 /// 0 | 1 | 1 (0 >= -1) | 1 2937 /// 1 | 0 | 0 (-1 >= 0) | 0 2938 /// 1 | 1 | 1 (-1 >= -1) | 1 2939 if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false)) 2940 return getTrue(ITy); 2941 break; 2942 case ICmpInst::ICMP_ULE: 2943 if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false)) 2944 return getTrue(ITy); 2945 break; 2946 case ICmpInst::ICMP_SLE: 2947 /// SLE follows the same logic as SGE with the LHS and RHS swapped. 2948 if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false)) 2949 return getTrue(ITy); 2950 break; 2951 } 2952 2953 return nullptr; 2954 } 2955 2956 /// Try hard to fold icmp with zero RHS because this is a common case. 2957 static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS, 2958 Value *RHS, const SimplifyQuery &Q) { 2959 if (!match(RHS, m_Zero())) 2960 return nullptr; 2961 2962 Type *ITy = getCompareTy(LHS); // The return type. 2963 switch (Pred) { 2964 default: 2965 llvm_unreachable("Unknown ICmp predicate!"); 2966 case ICmpInst::ICMP_ULT: 2967 return getFalse(ITy); 2968 case ICmpInst::ICMP_UGE: 2969 return getTrue(ITy); 2970 case ICmpInst::ICMP_EQ: 2971 case ICmpInst::ICMP_ULE: 2972 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2973 return getFalse(ITy); 2974 break; 2975 case ICmpInst::ICMP_NE: 2976 case ICmpInst::ICMP_UGT: 2977 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2978 return getTrue(ITy); 2979 break; 2980 case ICmpInst::ICMP_SLT: { 2981 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 2982 if (LHSKnown.isNegative()) 2983 return getTrue(ITy); 2984 if (LHSKnown.isNonNegative()) 2985 return getFalse(ITy); 2986 break; 2987 } 2988 case ICmpInst::ICMP_SLE: { 2989 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 2990 if (LHSKnown.isNegative()) 2991 return getTrue(ITy); 2992 if (LHSKnown.isNonNegative() && 2993 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2994 return getFalse(ITy); 2995 break; 2996 } 2997 case ICmpInst::ICMP_SGE: { 2998 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 2999 if (LHSKnown.isNegative()) 3000 return getFalse(ITy); 3001 if (LHSKnown.isNonNegative()) 3002 return getTrue(ITy); 3003 break; 3004 } 3005 case ICmpInst::ICMP_SGT: { 3006 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 3007 if (LHSKnown.isNegative()) 3008 return getFalse(ITy); 3009 if (LHSKnown.isNonNegative() && 3010 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 3011 return getTrue(ITy); 3012 break; 3013 } 3014 } 3015 3016 return nullptr; 3017 } 3018 3019 static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS, 3020 Value *RHS, const InstrInfoQuery &IIQ) { 3021 Type *ITy = getCompareTy(RHS); // The return type. 3022 3023 Value *X; 3024 // Sign-bit checks can be optimized to true/false after unsigned 3025 // floating-point casts: 3026 // icmp slt (bitcast (uitofp X)), 0 --> false 3027 // icmp sgt (bitcast (uitofp X)), -1 --> true 3028 if (match(LHS, m_BitCast(m_UIToFP(m_Value(X))))) { 3029 if (Pred == ICmpInst::ICMP_SLT && match(RHS, m_Zero())) 3030 return ConstantInt::getFalse(ITy); 3031 if (Pred == ICmpInst::ICMP_SGT && match(RHS, m_AllOnes())) 3032 return ConstantInt::getTrue(ITy); 3033 } 3034 3035 const APInt *C; 3036 if (!match(RHS, m_APIntAllowUndef(C))) 3037 return nullptr; 3038 3039 // Rule out tautological comparisons (eg., ult 0 or uge 0). 3040 ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C); 3041 if (RHS_CR.isEmptySet()) 3042 return ConstantInt::getFalse(ITy); 3043 if (RHS_CR.isFullSet()) 3044 return ConstantInt::getTrue(ITy); 3045 3046 ConstantRange LHS_CR = 3047 computeConstantRange(LHS, CmpInst::isSigned(Pred), IIQ.UseInstrInfo); 3048 if (!LHS_CR.isFullSet()) { 3049 if (RHS_CR.contains(LHS_CR)) 3050 return ConstantInt::getTrue(ITy); 3051 if (RHS_CR.inverse().contains(LHS_CR)) 3052 return ConstantInt::getFalse(ITy); 3053 } 3054 3055 // (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC) 3056 // (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC) 3057 const APInt *MulC; 3058 if (IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) && 3059 ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowUndef(MulC))) && 3060 *MulC != 0 && C->urem(*MulC) != 0) || 3061 (match(LHS, m_NSWMul(m_Value(), m_APIntAllowUndef(MulC))) && 3062 *MulC != 0 && C->srem(*MulC) != 0))) 3063 return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE); 3064 3065 return nullptr; 3066 } 3067 3068 static Value *simplifyICmpWithBinOpOnLHS(CmpInst::Predicate Pred, 3069 BinaryOperator *LBO, Value *RHS, 3070 const SimplifyQuery &Q, 3071 unsigned MaxRecurse) { 3072 Type *ITy = getCompareTy(RHS); // The return type. 3073 3074 Value *Y = nullptr; 3075 // icmp pred (or X, Y), X 3076 if (match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) { 3077 if (Pred == ICmpInst::ICMP_ULT) 3078 return getFalse(ITy); 3079 if (Pred == ICmpInst::ICMP_UGE) 3080 return getTrue(ITy); 3081 3082 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) { 3083 KnownBits RHSKnown = computeKnownBits(RHS, /* Depth */ 0, Q); 3084 KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 3085 if (RHSKnown.isNonNegative() && YKnown.isNegative()) 3086 return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy); 3087 if (RHSKnown.isNegative() || YKnown.isNonNegative()) 3088 return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy); 3089 } 3090 } 3091 3092 // icmp pred (and X, Y), X 3093 if (match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) { 3094 if (Pred == ICmpInst::ICMP_UGT) 3095 return getFalse(ITy); 3096 if (Pred == ICmpInst::ICMP_ULE) 3097 return getTrue(ITy); 3098 } 3099 3100 // icmp pred (urem X, Y), Y 3101 if (match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 3102 switch (Pred) { 3103 default: 3104 break; 3105 case ICmpInst::ICMP_SGT: 3106 case ICmpInst::ICMP_SGE: { 3107 KnownBits Known = computeKnownBits(RHS, /* Depth */ 0, Q); 3108 if (!Known.isNonNegative()) 3109 break; 3110 [[fallthrough]]; 3111 } 3112 case ICmpInst::ICMP_EQ: 3113 case ICmpInst::ICMP_UGT: 3114 case ICmpInst::ICMP_UGE: 3115 return getFalse(ITy); 3116 case ICmpInst::ICMP_SLT: 3117 case ICmpInst::ICMP_SLE: { 3118 KnownBits Known = computeKnownBits(RHS, /* Depth */ 0, Q); 3119 if (!Known.isNonNegative()) 3120 break; 3121 [[fallthrough]]; 3122 } 3123 case ICmpInst::ICMP_NE: 3124 case ICmpInst::ICMP_ULT: 3125 case ICmpInst::ICMP_ULE: 3126 return getTrue(ITy); 3127 } 3128 } 3129 3130 // icmp pred (urem X, Y), X 3131 if (match(LBO, m_URem(m_Specific(RHS), m_Value()))) { 3132 if (Pred == ICmpInst::ICMP_ULE) 3133 return getTrue(ITy); 3134 if (Pred == ICmpInst::ICMP_UGT) 3135 return getFalse(ITy); 3136 } 3137 3138 // x >>u y <=u x --> true. 3139 // x >>u y >u x --> false. 3140 // x udiv y <=u x --> true. 3141 // x udiv y >u x --> false. 3142 if (match(LBO, m_LShr(m_Specific(RHS), m_Value())) || 3143 match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) { 3144 // icmp pred (X op Y), X 3145 if (Pred == ICmpInst::ICMP_UGT) 3146 return getFalse(ITy); 3147 if (Pred == ICmpInst::ICMP_ULE) 3148 return getTrue(ITy); 3149 } 3150 3151 // If x is nonzero: 3152 // x >>u C <u x --> true for C != 0. 3153 // x >>u C != x --> true for C != 0. 3154 // x >>u C >=u x --> false for C != 0. 3155 // x >>u C == x --> false for C != 0. 3156 // x udiv C <u x --> true for C != 1. 3157 // x udiv C != x --> true for C != 1. 3158 // x udiv C >=u x --> false for C != 1. 3159 // x udiv C == x --> false for C != 1. 3160 // TODO: allow non-constant shift amount/divisor 3161 const APInt *C; 3162 if ((match(LBO, m_LShr(m_Specific(RHS), m_APInt(C))) && *C != 0) || 3163 (match(LBO, m_UDiv(m_Specific(RHS), m_APInt(C))) && *C != 1)) { 3164 if (isKnownNonZero(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) { 3165 switch (Pred) { 3166 default: 3167 break; 3168 case ICmpInst::ICMP_EQ: 3169 case ICmpInst::ICMP_UGE: 3170 return getFalse(ITy); 3171 case ICmpInst::ICMP_NE: 3172 case ICmpInst::ICMP_ULT: 3173 return getTrue(ITy); 3174 case ICmpInst::ICMP_UGT: 3175 case ICmpInst::ICMP_ULE: 3176 // UGT/ULE are handled by the more general case just above 3177 llvm_unreachable("Unexpected UGT/ULE, should have been handled"); 3178 } 3179 } 3180 } 3181 3182 // (x*C1)/C2 <= x for C1 <= C2. 3183 // This holds even if the multiplication overflows: Assume that x != 0 and 3184 // arithmetic is modulo M. For overflow to occur we must have C1 >= M/x and 3185 // thus C2 >= M/x. It follows that (x*C1)/C2 <= (M-1)/C2 <= ((M-1)*x)/M < x. 3186 // 3187 // Additionally, either the multiplication and division might be represented 3188 // as shifts: 3189 // (x*C1)>>C2 <= x for C1 < 2**C2. 3190 // (x<<C1)/C2 <= x for 2**C1 < C2. 3191 const APInt *C1, *C2; 3192 if ((match(LBO, m_UDiv(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3193 C1->ule(*C2)) || 3194 (match(LBO, m_LShr(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3195 C1->ule(APInt(C2->getBitWidth(), 1) << *C2)) || 3196 (match(LBO, m_UDiv(m_Shl(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3197 (APInt(C1->getBitWidth(), 1) << *C1).ule(*C2))) { 3198 if (Pred == ICmpInst::ICMP_UGT) 3199 return getFalse(ITy); 3200 if (Pred == ICmpInst::ICMP_ULE) 3201 return getTrue(ITy); 3202 } 3203 3204 // (sub C, X) == X, C is odd --> false 3205 // (sub C, X) != X, C is odd --> true 3206 if (match(LBO, m_Sub(m_APIntAllowUndef(C), m_Specific(RHS))) && 3207 (*C & 1) == 1 && ICmpInst::isEquality(Pred)) 3208 return (Pred == ICmpInst::ICMP_EQ) ? getFalse(ITy) : getTrue(ITy); 3209 3210 return nullptr; 3211 } 3212 3213 // If only one of the icmp's operands has NSW flags, try to prove that: 3214 // 3215 // icmp slt (x + C1), (x +nsw C2) 3216 // 3217 // is equivalent to: 3218 // 3219 // icmp slt C1, C2 3220 // 3221 // which is true if x + C2 has the NSW flags set and: 3222 // *) C1 < C2 && C1 >= 0, or 3223 // *) C2 < C1 && C1 <= 0. 3224 // 3225 static bool trySimplifyICmpWithAdds(CmpInst::Predicate Pred, Value *LHS, 3226 Value *RHS, const InstrInfoQuery &IIQ) { 3227 // TODO: only support icmp slt for now. 3228 if (Pred != CmpInst::ICMP_SLT || !IIQ.UseInstrInfo) 3229 return false; 3230 3231 // Canonicalize nsw add as RHS. 3232 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 3233 std::swap(LHS, RHS); 3234 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 3235 return false; 3236 3237 Value *X; 3238 const APInt *C1, *C2; 3239 if (!match(LHS, m_c_Add(m_Value(X), m_APInt(C1))) || 3240 !match(RHS, m_c_Add(m_Specific(X), m_APInt(C2)))) 3241 return false; 3242 3243 return (C1->slt(*C2) && C1->isNonNegative()) || 3244 (C2->slt(*C1) && C1->isNonPositive()); 3245 } 3246 3247 /// TODO: A large part of this logic is duplicated in InstCombine's 3248 /// foldICmpBinOp(). We should be able to share that and avoid the code 3249 /// duplication. 3250 static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS, 3251 Value *RHS, const SimplifyQuery &Q, 3252 unsigned MaxRecurse) { 3253 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 3254 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 3255 if (MaxRecurse && (LBO || RBO)) { 3256 // Analyze the case when either LHS or RHS is an add instruction. 3257 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr; 3258 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 3259 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 3260 if (LBO && LBO->getOpcode() == Instruction::Add) { 3261 A = LBO->getOperand(0); 3262 B = LBO->getOperand(1); 3263 NoLHSWrapProblem = 3264 ICmpInst::isEquality(Pred) || 3265 (CmpInst::isUnsigned(Pred) && 3266 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) || 3267 (CmpInst::isSigned(Pred) && 3268 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO))); 3269 } 3270 if (RBO && RBO->getOpcode() == Instruction::Add) { 3271 C = RBO->getOperand(0); 3272 D = RBO->getOperand(1); 3273 NoRHSWrapProblem = 3274 ICmpInst::isEquality(Pred) || 3275 (CmpInst::isUnsigned(Pred) && 3276 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) || 3277 (CmpInst::isSigned(Pred) && 3278 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO))); 3279 } 3280 3281 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 3282 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 3283 if (Value *V = simplifyICmpInst(Pred, A == RHS ? B : A, 3284 Constant::getNullValue(RHS->getType()), Q, 3285 MaxRecurse - 1)) 3286 return V; 3287 3288 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 3289 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 3290 if (Value *V = 3291 simplifyICmpInst(Pred, Constant::getNullValue(LHS->getType()), 3292 C == LHS ? D : C, Q, MaxRecurse - 1)) 3293 return V; 3294 3295 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 3296 bool CanSimplify = (NoLHSWrapProblem && NoRHSWrapProblem) || 3297 trySimplifyICmpWithAdds(Pred, LHS, RHS, Q.IIQ); 3298 if (A && C && (A == C || A == D || B == C || B == D) && CanSimplify) { 3299 // Determine Y and Z in the form icmp (X+Y), (X+Z). 3300 Value *Y, *Z; 3301 if (A == C) { 3302 // C + B == C + D -> B == D 3303 Y = B; 3304 Z = D; 3305 } else if (A == D) { 3306 // D + B == C + D -> B == C 3307 Y = B; 3308 Z = C; 3309 } else if (B == C) { 3310 // A + C == C + D -> A == D 3311 Y = A; 3312 Z = D; 3313 } else { 3314 assert(B == D); 3315 // A + D == C + D -> A == C 3316 Y = A; 3317 Z = C; 3318 } 3319 if (Value *V = simplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1)) 3320 return V; 3321 } 3322 } 3323 3324 if (LBO) 3325 if (Value *V = simplifyICmpWithBinOpOnLHS(Pred, LBO, RHS, Q, MaxRecurse)) 3326 return V; 3327 3328 if (RBO) 3329 if (Value *V = simplifyICmpWithBinOpOnLHS( 3330 ICmpInst::getSwappedPredicate(Pred), RBO, LHS, Q, MaxRecurse)) 3331 return V; 3332 3333 // 0 - (zext X) pred C 3334 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) { 3335 const APInt *C; 3336 if (match(RHS, m_APInt(C))) { 3337 if (C->isStrictlyPositive()) { 3338 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_NE) 3339 return ConstantInt::getTrue(getCompareTy(RHS)); 3340 if (Pred == ICmpInst::ICMP_SGE || Pred == ICmpInst::ICMP_EQ) 3341 return ConstantInt::getFalse(getCompareTy(RHS)); 3342 } 3343 if (C->isNonNegative()) { 3344 if (Pred == ICmpInst::ICMP_SLE) 3345 return ConstantInt::getTrue(getCompareTy(RHS)); 3346 if (Pred == ICmpInst::ICMP_SGT) 3347 return ConstantInt::getFalse(getCompareTy(RHS)); 3348 } 3349 } 3350 } 3351 3352 // If C2 is a power-of-2 and C is not: 3353 // (C2 << X) == C --> false 3354 // (C2 << X) != C --> true 3355 const APInt *C; 3356 if (match(LHS, m_Shl(m_Power2(), m_Value())) && 3357 match(RHS, m_APIntAllowUndef(C)) && !C->isPowerOf2()) { 3358 // C2 << X can equal zero in some circumstances. 3359 // This simplification might be unsafe if C is zero. 3360 // 3361 // We know it is safe if: 3362 // - The shift is nsw. We can't shift out the one bit. 3363 // - The shift is nuw. We can't shift out the one bit. 3364 // - C2 is one. 3365 // - C isn't zero. 3366 if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3367 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3368 match(LHS, m_Shl(m_One(), m_Value())) || !C->isZero()) { 3369 if (Pred == ICmpInst::ICMP_EQ) 3370 return ConstantInt::getFalse(getCompareTy(RHS)); 3371 if (Pred == ICmpInst::ICMP_NE) 3372 return ConstantInt::getTrue(getCompareTy(RHS)); 3373 } 3374 } 3375 3376 // If C is a power-of-2: 3377 // (C << X) >u 0x8000 --> false 3378 // (C << X) <=u 0x8000 --> true 3379 if (match(LHS, m_Shl(m_Power2(), m_Value())) && match(RHS, m_SignMask())) { 3380 if (Pred == ICmpInst::ICMP_UGT) 3381 return ConstantInt::getFalse(getCompareTy(RHS)); 3382 if (Pred == ICmpInst::ICMP_ULE) 3383 return ConstantInt::getTrue(getCompareTy(RHS)); 3384 } 3385 3386 if (!MaxRecurse || !LBO || !RBO || LBO->getOpcode() != RBO->getOpcode()) 3387 return nullptr; 3388 3389 if (LBO->getOperand(0) == RBO->getOperand(0)) { 3390 switch (LBO->getOpcode()) { 3391 default: 3392 break; 3393 case Instruction::Shl: { 3394 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3395 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3396 if (!NUW || (ICmpInst::isSigned(Pred) && !NSW) || 3397 !isKnownNonZero(LBO->getOperand(0), Q.DL)) 3398 break; 3399 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(1), 3400 RBO->getOperand(1), Q, MaxRecurse - 1)) 3401 return V; 3402 break; 3403 } 3404 // If C1 & C2 == C1, A = X and/or C1, B = X and/or C2: 3405 // icmp ule A, B -> true 3406 // icmp ugt A, B -> false 3407 // icmp sle A, B -> true (C1 and C2 are the same sign) 3408 // icmp sgt A, B -> false (C1 and C2 are the same sign) 3409 case Instruction::And: 3410 case Instruction::Or: { 3411 const APInt *C1, *C2; 3412 if (ICmpInst::isRelational(Pred) && 3413 match(LBO->getOperand(1), m_APInt(C1)) && 3414 match(RBO->getOperand(1), m_APInt(C2))) { 3415 if (!C1->isSubsetOf(*C2)) { 3416 std::swap(C1, C2); 3417 Pred = ICmpInst::getSwappedPredicate(Pred); 3418 } 3419 if (C1->isSubsetOf(*C2)) { 3420 if (Pred == ICmpInst::ICMP_ULE) 3421 return ConstantInt::getTrue(getCompareTy(LHS)); 3422 if (Pred == ICmpInst::ICMP_UGT) 3423 return ConstantInt::getFalse(getCompareTy(LHS)); 3424 if (C1->isNonNegative() == C2->isNonNegative()) { 3425 if (Pred == ICmpInst::ICMP_SLE) 3426 return ConstantInt::getTrue(getCompareTy(LHS)); 3427 if (Pred == ICmpInst::ICMP_SGT) 3428 return ConstantInt::getFalse(getCompareTy(LHS)); 3429 } 3430 } 3431 } 3432 break; 3433 } 3434 } 3435 } 3436 3437 if (LBO->getOperand(1) == RBO->getOperand(1)) { 3438 switch (LBO->getOpcode()) { 3439 default: 3440 break; 3441 case Instruction::UDiv: 3442 case Instruction::LShr: 3443 if (ICmpInst::isSigned(Pred) || !Q.IIQ.isExact(LBO) || 3444 !Q.IIQ.isExact(RBO)) 3445 break; 3446 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3447 RBO->getOperand(0), Q, MaxRecurse - 1)) 3448 return V; 3449 break; 3450 case Instruction::SDiv: 3451 if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) || 3452 !Q.IIQ.isExact(RBO)) 3453 break; 3454 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3455 RBO->getOperand(0), Q, MaxRecurse - 1)) 3456 return V; 3457 break; 3458 case Instruction::AShr: 3459 if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO)) 3460 break; 3461 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3462 RBO->getOperand(0), Q, MaxRecurse - 1)) 3463 return V; 3464 break; 3465 case Instruction::Shl: { 3466 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3467 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3468 if (!NUW && !NSW) 3469 break; 3470 if (!NSW && ICmpInst::isSigned(Pred)) 3471 break; 3472 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3473 RBO->getOperand(0), Q, MaxRecurse - 1)) 3474 return V; 3475 break; 3476 } 3477 } 3478 } 3479 return nullptr; 3480 } 3481 3482 /// simplify integer comparisons where at least one operand of the compare 3483 /// matches an integer min/max idiom. 3484 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS, 3485 Value *RHS, const SimplifyQuery &Q, 3486 unsigned MaxRecurse) { 3487 Type *ITy = getCompareTy(LHS); // The return type. 3488 Value *A, *B; 3489 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 3490 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 3491 3492 // Signed variants on "max(a,b)>=a -> true". 3493 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3494 if (A != RHS) 3495 std::swap(A, B); // smax(A, B) pred A. 3496 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3497 // We analyze this as smax(A, B) pred A. 3498 P = Pred; 3499 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 3500 (A == LHS || B == LHS)) { 3501 if (A != LHS) 3502 std::swap(A, B); // A pred smax(A, B). 3503 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3504 // We analyze this as smax(A, B) swapped-pred A. 3505 P = CmpInst::getSwappedPredicate(Pred); 3506 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 3507 (A == RHS || B == RHS)) { 3508 if (A != RHS) 3509 std::swap(A, B); // smin(A, B) pred A. 3510 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3511 // We analyze this as smax(-A, -B) swapped-pred -A. 3512 // Note that we do not need to actually form -A or -B thanks to EqP. 3513 P = CmpInst::getSwappedPredicate(Pred); 3514 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 3515 (A == LHS || B == LHS)) { 3516 if (A != LHS) 3517 std::swap(A, B); // A pred smin(A, B). 3518 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3519 // We analyze this as smax(-A, -B) pred -A. 3520 // Note that we do not need to actually form -A or -B thanks to EqP. 3521 P = Pred; 3522 } 3523 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3524 // Cases correspond to "max(A, B) p A". 3525 switch (P) { 3526 default: 3527 break; 3528 case CmpInst::ICMP_EQ: 3529 case CmpInst::ICMP_SLE: 3530 // Equivalent to "A EqP B". This may be the same as the condition tested 3531 // in the max/min; if so, we can just return that. 3532 if (Value *V = extractEquivalentCondition(LHS, EqP, A, B)) 3533 return V; 3534 if (Value *V = extractEquivalentCondition(RHS, EqP, A, B)) 3535 return V; 3536 // Otherwise, see if "A EqP B" simplifies. 3537 if (MaxRecurse) 3538 if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3539 return V; 3540 break; 3541 case CmpInst::ICMP_NE: 3542 case CmpInst::ICMP_SGT: { 3543 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3544 // Equivalent to "A InvEqP B". This may be the same as the condition 3545 // tested in the max/min; if so, we can just return that. 3546 if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B)) 3547 return V; 3548 if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B)) 3549 return V; 3550 // Otherwise, see if "A InvEqP B" simplifies. 3551 if (MaxRecurse) 3552 if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3553 return V; 3554 break; 3555 } 3556 case CmpInst::ICMP_SGE: 3557 // Always true. 3558 return getTrue(ITy); 3559 case CmpInst::ICMP_SLT: 3560 // Always false. 3561 return getFalse(ITy); 3562 } 3563 } 3564 3565 // Unsigned variants on "max(a,b)>=a -> true". 3566 P = CmpInst::BAD_ICMP_PREDICATE; 3567 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3568 if (A != RHS) 3569 std::swap(A, B); // umax(A, B) pred A. 3570 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3571 // We analyze this as umax(A, B) pred A. 3572 P = Pred; 3573 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 3574 (A == LHS || B == LHS)) { 3575 if (A != LHS) 3576 std::swap(A, B); // A pred umax(A, B). 3577 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3578 // We analyze this as umax(A, B) swapped-pred A. 3579 P = CmpInst::getSwappedPredicate(Pred); 3580 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 3581 (A == RHS || B == RHS)) { 3582 if (A != RHS) 3583 std::swap(A, B); // umin(A, B) pred A. 3584 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3585 // We analyze this as umax(-A, -B) swapped-pred -A. 3586 // Note that we do not need to actually form -A or -B thanks to EqP. 3587 P = CmpInst::getSwappedPredicate(Pred); 3588 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 3589 (A == LHS || B == LHS)) { 3590 if (A != LHS) 3591 std::swap(A, B); // A pred umin(A, B). 3592 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3593 // We analyze this as umax(-A, -B) pred -A. 3594 // Note that we do not need to actually form -A or -B thanks to EqP. 3595 P = Pred; 3596 } 3597 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3598 // Cases correspond to "max(A, B) p A". 3599 switch (P) { 3600 default: 3601 break; 3602 case CmpInst::ICMP_EQ: 3603 case CmpInst::ICMP_ULE: 3604 // Equivalent to "A EqP B". This may be the same as the condition tested 3605 // in the max/min; if so, we can just return that. 3606 if (Value *V = extractEquivalentCondition(LHS, EqP, A, B)) 3607 return V; 3608 if (Value *V = extractEquivalentCondition(RHS, EqP, A, B)) 3609 return V; 3610 // Otherwise, see if "A EqP B" simplifies. 3611 if (MaxRecurse) 3612 if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3613 return V; 3614 break; 3615 case CmpInst::ICMP_NE: 3616 case CmpInst::ICMP_UGT: { 3617 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3618 // Equivalent to "A InvEqP B". This may be the same as the condition 3619 // tested in the max/min; if so, we can just return that. 3620 if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B)) 3621 return V; 3622 if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B)) 3623 return V; 3624 // Otherwise, see if "A InvEqP B" simplifies. 3625 if (MaxRecurse) 3626 if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3627 return V; 3628 break; 3629 } 3630 case CmpInst::ICMP_UGE: 3631 return getTrue(ITy); 3632 case CmpInst::ICMP_ULT: 3633 return getFalse(ITy); 3634 } 3635 } 3636 3637 // Comparing 1 each of min/max with a common operand? 3638 // Canonicalize min operand to RHS. 3639 if (match(LHS, m_UMin(m_Value(), m_Value())) || 3640 match(LHS, m_SMin(m_Value(), m_Value()))) { 3641 std::swap(LHS, RHS); 3642 Pred = ICmpInst::getSwappedPredicate(Pred); 3643 } 3644 3645 Value *C, *D; 3646 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 3647 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 3648 (A == C || A == D || B == C || B == D)) { 3649 // smax(A, B) >=s smin(A, D) --> true 3650 if (Pred == CmpInst::ICMP_SGE) 3651 return getTrue(ITy); 3652 // smax(A, B) <s smin(A, D) --> false 3653 if (Pred == CmpInst::ICMP_SLT) 3654 return getFalse(ITy); 3655 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 3656 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 3657 (A == C || A == D || B == C || B == D)) { 3658 // umax(A, B) >=u umin(A, D) --> true 3659 if (Pred == CmpInst::ICMP_UGE) 3660 return getTrue(ITy); 3661 // umax(A, B) <u umin(A, D) --> false 3662 if (Pred == CmpInst::ICMP_ULT) 3663 return getFalse(ITy); 3664 } 3665 3666 return nullptr; 3667 } 3668 3669 static Value *simplifyICmpWithDominatingAssume(CmpInst::Predicate Predicate, 3670 Value *LHS, Value *RHS, 3671 const SimplifyQuery &Q) { 3672 // Gracefully handle instructions that have not been inserted yet. 3673 if (!Q.AC || !Q.CxtI) 3674 return nullptr; 3675 3676 for (Value *AssumeBaseOp : {LHS, RHS}) { 3677 for (auto &AssumeVH : Q.AC->assumptionsFor(AssumeBaseOp)) { 3678 if (!AssumeVH) 3679 continue; 3680 3681 CallInst *Assume = cast<CallInst>(AssumeVH); 3682 if (std::optional<bool> Imp = isImpliedCondition( 3683 Assume->getArgOperand(0), Predicate, LHS, RHS, Q.DL)) 3684 if (isValidAssumeForContext(Assume, Q.CxtI, Q.DT)) 3685 return ConstantInt::get(getCompareTy(LHS), *Imp); 3686 } 3687 } 3688 3689 return nullptr; 3690 } 3691 3692 static Value *simplifyICmpWithIntrinsicOnLHS(CmpInst::Predicate Pred, 3693 Value *LHS, Value *RHS) { 3694 auto *II = dyn_cast<IntrinsicInst>(LHS); 3695 if (!II) 3696 return nullptr; 3697 3698 switch (II->getIntrinsicID()) { 3699 case Intrinsic::uadd_sat: 3700 // uadd.sat(X, Y) uge X, uadd.sat(X, Y) uge Y 3701 if (II->getArgOperand(0) == RHS || II->getArgOperand(1) == RHS) { 3702 if (Pred == ICmpInst::ICMP_UGE) 3703 return ConstantInt::getTrue(getCompareTy(II)); 3704 if (Pred == ICmpInst::ICMP_ULT) 3705 return ConstantInt::getFalse(getCompareTy(II)); 3706 } 3707 return nullptr; 3708 case Intrinsic::usub_sat: 3709 // usub.sat(X, Y) ule X 3710 if (II->getArgOperand(0) == RHS) { 3711 if (Pred == ICmpInst::ICMP_ULE) 3712 return ConstantInt::getTrue(getCompareTy(II)); 3713 if (Pred == ICmpInst::ICMP_UGT) 3714 return ConstantInt::getFalse(getCompareTy(II)); 3715 } 3716 return nullptr; 3717 default: 3718 return nullptr; 3719 } 3720 } 3721 3722 /// Given operands for an ICmpInst, see if we can fold the result. 3723 /// If not, this returns null. 3724 static Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3725 const SimplifyQuery &Q, unsigned MaxRecurse) { 3726 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 3727 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 3728 3729 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 3730 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 3731 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); 3732 3733 // If we have a constant, make sure it is on the RHS. 3734 std::swap(LHS, RHS); 3735 Pred = CmpInst::getSwappedPredicate(Pred); 3736 } 3737 assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X"); 3738 3739 Type *ITy = getCompareTy(LHS); // The return type. 3740 3741 // icmp poison, X -> poison 3742 if (isa<PoisonValue>(RHS)) 3743 return PoisonValue::get(ITy); 3744 3745 // For EQ and NE, we can always pick a value for the undef to make the 3746 // predicate pass or fail, so we can return undef. 3747 // Matches behavior in llvm::ConstantFoldCompareInstruction. 3748 if (Q.isUndefValue(RHS) && ICmpInst::isEquality(Pred)) 3749 return UndefValue::get(ITy); 3750 3751 // icmp X, X -> true/false 3752 // icmp X, undef -> true/false because undef could be X. 3753 if (LHS == RHS || Q.isUndefValue(RHS)) 3754 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 3755 3756 if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q)) 3757 return V; 3758 3759 // TODO: Sink/common this with other potentially expensive calls that use 3760 // ValueTracking? See comment below for isKnownNonEqual(). 3761 if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q)) 3762 return V; 3763 3764 if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ)) 3765 return V; 3766 3767 // If both operands have range metadata, use the metadata 3768 // to simplify the comparison. 3769 if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) { 3770 auto RHS_Instr = cast<Instruction>(RHS); 3771 auto LHS_Instr = cast<Instruction>(LHS); 3772 3773 if (Q.IIQ.getMetadata(RHS_Instr, LLVMContext::MD_range) && 3774 Q.IIQ.getMetadata(LHS_Instr, LLVMContext::MD_range)) { 3775 auto RHS_CR = getConstantRangeFromMetadata( 3776 *RHS_Instr->getMetadata(LLVMContext::MD_range)); 3777 auto LHS_CR = getConstantRangeFromMetadata( 3778 *LHS_Instr->getMetadata(LLVMContext::MD_range)); 3779 3780 if (LHS_CR.icmp(Pred, RHS_CR)) 3781 return ConstantInt::getTrue(RHS->getContext()); 3782 3783 if (LHS_CR.icmp(CmpInst::getInversePredicate(Pred), RHS_CR)) 3784 return ConstantInt::getFalse(RHS->getContext()); 3785 } 3786 } 3787 3788 // Compare of cast, for example (zext X) != 0 -> X != 0 3789 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 3790 Instruction *LI = cast<CastInst>(LHS); 3791 Value *SrcOp = LI->getOperand(0); 3792 Type *SrcTy = SrcOp->getType(); 3793 Type *DstTy = LI->getType(); 3794 3795 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 3796 // if the integer type is the same size as the pointer type. 3797 if (MaxRecurse && isa<PtrToIntInst>(LI) && 3798 Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) { 3799 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 3800 // Transfer the cast to the constant. 3801 if (Value *V = simplifyICmpInst(Pred, SrcOp, 3802 ConstantExpr::getIntToPtr(RHSC, SrcTy), 3803 Q, MaxRecurse - 1)) 3804 return V; 3805 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 3806 if (RI->getOperand(0)->getType() == SrcTy) 3807 // Compare without the cast. 3808 if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q, 3809 MaxRecurse - 1)) 3810 return V; 3811 } 3812 } 3813 3814 if (isa<ZExtInst>(LHS)) { 3815 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 3816 // same type. 3817 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3818 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3819 // Compare X and Y. Note that signed predicates become unsigned. 3820 if (Value *V = 3821 simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), SrcOp, 3822 RI->getOperand(0), Q, MaxRecurse - 1)) 3823 return V; 3824 } 3825 // Fold (zext X) ule (sext X), (zext X) sge (sext X) to true. 3826 else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3827 if (SrcOp == RI->getOperand(0)) { 3828 if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE) 3829 return ConstantInt::getTrue(ITy); 3830 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT) 3831 return ConstantInt::getFalse(ITy); 3832 } 3833 } 3834 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 3835 // too. If not, then try to deduce the result of the comparison. 3836 else if (match(RHS, m_ImmConstant())) { 3837 Constant *C = dyn_cast<Constant>(RHS); 3838 assert(C != nullptr); 3839 3840 // Compute the constant that would happen if we truncated to SrcTy then 3841 // reextended to DstTy. 3842 Constant *Trunc = 3843 ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL); 3844 assert(Trunc && "Constant-fold of ImmConstant should not fail"); 3845 Constant *RExt = 3846 ConstantFoldCastOperand(CastInst::ZExt, Trunc, DstTy, Q.DL); 3847 assert(RExt && "Constant-fold of ImmConstant should not fail"); 3848 Constant *AnyEq = 3849 ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL); 3850 assert(AnyEq && "Constant-fold of ImmConstant should not fail"); 3851 3852 // If the re-extended constant didn't change any of the elements then 3853 // this is effectively also a case of comparing two zero-extended 3854 // values. 3855 if (AnyEq->isAllOnesValue() && MaxRecurse) 3856 if (Value *V = simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 3857 SrcOp, Trunc, Q, MaxRecurse - 1)) 3858 return V; 3859 3860 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 3861 // there. Use this to work out the result of the comparison. 3862 if (AnyEq->isNullValue()) { 3863 switch (Pred) { 3864 default: 3865 llvm_unreachable("Unknown ICmp predicate!"); 3866 // LHS <u RHS. 3867 case ICmpInst::ICMP_EQ: 3868 case ICmpInst::ICMP_UGT: 3869 case ICmpInst::ICMP_UGE: 3870 return Constant::getNullValue(ITy); 3871 3872 case ICmpInst::ICMP_NE: 3873 case ICmpInst::ICMP_ULT: 3874 case ICmpInst::ICMP_ULE: 3875 return Constant::getAllOnesValue(ITy); 3876 3877 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 3878 // is non-negative then LHS <s RHS. 3879 case ICmpInst::ICMP_SGT: 3880 case ICmpInst::ICMP_SGE: 3881 return ConstantFoldCompareInstOperands( 3882 ICmpInst::ICMP_SLT, C, Constant::getNullValue(C->getType()), 3883 Q.DL); 3884 case ICmpInst::ICMP_SLT: 3885 case ICmpInst::ICMP_SLE: 3886 return ConstantFoldCompareInstOperands( 3887 ICmpInst::ICMP_SGE, C, Constant::getNullValue(C->getType()), 3888 Q.DL); 3889 } 3890 } 3891 } 3892 } 3893 3894 if (isa<SExtInst>(LHS)) { 3895 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 3896 // same type. 3897 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3898 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3899 // Compare X and Y. Note that the predicate does not change. 3900 if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q, 3901 MaxRecurse - 1)) 3902 return V; 3903 } 3904 // Fold (sext X) uge (zext X), (sext X) sle (zext X) to true. 3905 else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3906 if (SrcOp == RI->getOperand(0)) { 3907 if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE) 3908 return ConstantInt::getTrue(ITy); 3909 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT) 3910 return ConstantInt::getFalse(ITy); 3911 } 3912 } 3913 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 3914 // too. If not, then try to deduce the result of the comparison. 3915 else if (match(RHS, m_ImmConstant())) { 3916 Constant *C = cast<Constant>(RHS); 3917 3918 // Compute the constant that would happen if we truncated to SrcTy then 3919 // reextended to DstTy. 3920 Constant *Trunc = 3921 ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL); 3922 assert(Trunc && "Constant-fold of ImmConstant should not fail"); 3923 Constant *RExt = 3924 ConstantFoldCastOperand(CastInst::SExt, Trunc, DstTy, Q.DL); 3925 assert(RExt && "Constant-fold of ImmConstant should not fail"); 3926 Constant *AnyEq = 3927 ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL); 3928 assert(AnyEq && "Constant-fold of ImmConstant should not fail"); 3929 3930 // If the re-extended constant didn't change then this is effectively 3931 // also a case of comparing two sign-extended values. 3932 if (AnyEq->isAllOnesValue() && MaxRecurse) 3933 if (Value *V = 3934 simplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse - 1)) 3935 return V; 3936 3937 // Otherwise the upper bits of LHS are all equal, while RHS has varying 3938 // bits there. Use this to work out the result of the comparison. 3939 if (AnyEq->isNullValue()) { 3940 switch (Pred) { 3941 default: 3942 llvm_unreachable("Unknown ICmp predicate!"); 3943 case ICmpInst::ICMP_EQ: 3944 return Constant::getNullValue(ITy); 3945 case ICmpInst::ICMP_NE: 3946 return Constant::getAllOnesValue(ITy); 3947 3948 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 3949 // LHS >s RHS. 3950 case ICmpInst::ICMP_SGT: 3951 case ICmpInst::ICMP_SGE: 3952 return ConstantExpr::getICmp(ICmpInst::ICMP_SLT, C, 3953 Constant::getNullValue(C->getType())); 3954 case ICmpInst::ICMP_SLT: 3955 case ICmpInst::ICMP_SLE: 3956 return ConstantExpr::getICmp(ICmpInst::ICMP_SGE, C, 3957 Constant::getNullValue(C->getType())); 3958 3959 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 3960 // LHS >u RHS. 3961 case ICmpInst::ICMP_UGT: 3962 case ICmpInst::ICMP_UGE: 3963 // Comparison is true iff the LHS <s 0. 3964 if (MaxRecurse) 3965 if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 3966 Constant::getNullValue(SrcTy), Q, 3967 MaxRecurse - 1)) 3968 return V; 3969 break; 3970 case ICmpInst::ICMP_ULT: 3971 case ICmpInst::ICMP_ULE: 3972 // Comparison is true iff the LHS >=s 0. 3973 if (MaxRecurse) 3974 if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 3975 Constant::getNullValue(SrcTy), Q, 3976 MaxRecurse - 1)) 3977 return V; 3978 break; 3979 } 3980 } 3981 } 3982 } 3983 } 3984 3985 // icmp eq|ne X, Y -> false|true if X != Y 3986 // This is potentially expensive, and we have already computedKnownBits for 3987 // compares with 0 above here, so only try this for a non-zero compare. 3988 if (ICmpInst::isEquality(Pred) && !match(RHS, m_Zero()) && 3989 isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) { 3990 return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy); 3991 } 3992 3993 if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse)) 3994 return V; 3995 3996 if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse)) 3997 return V; 3998 3999 if (Value *V = simplifyICmpWithIntrinsicOnLHS(Pred, LHS, RHS)) 4000 return V; 4001 if (Value *V = simplifyICmpWithIntrinsicOnLHS( 4002 ICmpInst::getSwappedPredicate(Pred), RHS, LHS)) 4003 return V; 4004 4005 if (Value *V = simplifyICmpWithDominatingAssume(Pred, LHS, RHS, Q)) 4006 return V; 4007 4008 if (std::optional<bool> Res = 4009 isImpliedByDomCondition(Pred, LHS, RHS, Q.CxtI, Q.DL)) 4010 return ConstantInt::getBool(ITy, *Res); 4011 4012 // Simplify comparisons of related pointers using a powerful, recursive 4013 // GEP-walk when we have target data available.. 4014 if (LHS->getType()->isPointerTy()) 4015 if (auto *C = computePointerICmp(Pred, LHS, RHS, Q)) 4016 return C; 4017 if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS)) 4018 if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS)) 4019 if (CLHS->getPointerOperandType() == CRHS->getPointerOperandType() && 4020 Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) == 4021 Q.DL.getTypeSizeInBits(CLHS->getType())) 4022 if (auto *C = computePointerICmp(Pred, CLHS->getPointerOperand(), 4023 CRHS->getPointerOperand(), Q)) 4024 return C; 4025 4026 // If the comparison is with the result of a select instruction, check whether 4027 // comparing with either branch of the select always yields the same value. 4028 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 4029 if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 4030 return V; 4031 4032 // If the comparison is with the result of a phi instruction, check whether 4033 // doing the compare with each incoming phi value yields a common result. 4034 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 4035 if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 4036 return V; 4037 4038 return nullptr; 4039 } 4040 4041 Value *llvm::simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4042 const SimplifyQuery &Q) { 4043 return ::simplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 4044 } 4045 4046 /// Given operands for an FCmpInst, see if we can fold the result. 4047 /// If not, this returns null. 4048 static Value *simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4049 FastMathFlags FMF, const SimplifyQuery &Q, 4050 unsigned MaxRecurse) { 4051 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 4052 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 4053 4054 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 4055 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 4056 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI, 4057 Q.CxtI); 4058 4059 // If we have a constant, make sure it is on the RHS. 4060 std::swap(LHS, RHS); 4061 Pred = CmpInst::getSwappedPredicate(Pred); 4062 } 4063 4064 // Fold trivial predicates. 4065 Type *RetTy = getCompareTy(LHS); 4066 if (Pred == FCmpInst::FCMP_FALSE) 4067 return getFalse(RetTy); 4068 if (Pred == FCmpInst::FCMP_TRUE) 4069 return getTrue(RetTy); 4070 4071 // fcmp pred x, poison and fcmp pred poison, x 4072 // fold to poison 4073 if (isa<PoisonValue>(LHS) || isa<PoisonValue>(RHS)) 4074 return PoisonValue::get(RetTy); 4075 4076 // fcmp pred x, undef and fcmp pred undef, x 4077 // fold to true if unordered, false if ordered 4078 if (Q.isUndefValue(LHS) || Q.isUndefValue(RHS)) { 4079 // Choosing NaN for the undef will always make unordered comparison succeed 4080 // and ordered comparison fail. 4081 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 4082 } 4083 4084 // fcmp x,x -> true/false. Not all compares are foldable. 4085 if (LHS == RHS) { 4086 if (CmpInst::isTrueWhenEqual(Pred)) 4087 return getTrue(RetTy); 4088 if (CmpInst::isFalseWhenEqual(Pred)) 4089 return getFalse(RetTy); 4090 } 4091 4092 // Fold (un)ordered comparison if we can determine there are no NaNs. 4093 // 4094 // This catches the 2 variable input case, constants are handled below as a 4095 // class-like compare. 4096 if (Pred == FCmpInst::FCMP_ORD || Pred == FCmpInst::FCMP_UNO) { 4097 if (FMF.noNaNs() || 4098 (isKnownNeverNaN(RHS, Q.DL, Q.TLI, 0, Q.AC, Q.CxtI, Q.DT) && 4099 isKnownNeverNaN(LHS, Q.DL, Q.TLI, 0, Q.AC, Q.CxtI, Q.DT))) 4100 return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD); 4101 } 4102 4103 const APFloat *C = nullptr; 4104 match(RHS, m_APFloatAllowUndef(C)); 4105 std::optional<KnownFPClass> FullKnownClassLHS; 4106 4107 // Lazily compute the possible classes for LHS. Avoid computing it twice if 4108 // RHS is a 0. 4109 auto computeLHSClass = [=, &FullKnownClassLHS](FPClassTest InterestedFlags = 4110 fcAllFlags) { 4111 if (FullKnownClassLHS) 4112 return *FullKnownClassLHS; 4113 return computeKnownFPClass(LHS, FMF, Q.DL, InterestedFlags, 0, Q.TLI, Q.AC, 4114 Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo); 4115 }; 4116 4117 if (C && Q.CxtI) { 4118 // Fold out compares that express a class test. 4119 // 4120 // FIXME: Should be able to perform folds without context 4121 // instruction. Always pass in the context function? 4122 4123 const Function *ParentF = Q.CxtI->getFunction(); 4124 auto [ClassVal, ClassTest] = fcmpToClassTest(Pred, *ParentF, LHS, C); 4125 if (ClassVal) { 4126 FullKnownClassLHS = computeLHSClass(); 4127 if ((FullKnownClassLHS->KnownFPClasses & ClassTest) == fcNone) 4128 return getFalse(RetTy); 4129 if ((FullKnownClassLHS->KnownFPClasses & ~ClassTest) == fcNone) 4130 return getTrue(RetTy); 4131 } 4132 } 4133 4134 // Handle fcmp with constant RHS. 4135 if (C) { 4136 // TODO: If we always required a context function, we wouldn't need to 4137 // special case nans. 4138 if (C->isNaN()) 4139 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 4140 4141 // TODO: Need version fcmpToClassTest which returns implied class when the 4142 // compare isn't a complete class test. e.g. > 1.0 implies fcPositive, but 4143 // isn't implementable as a class call. 4144 if (C->isNegative() && !C->isNegZero()) { 4145 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4146 4147 // TODO: We can catch more cases by using a range check rather than 4148 // relying on CannotBeOrderedLessThanZero. 4149 switch (Pred) { 4150 case FCmpInst::FCMP_UGE: 4151 case FCmpInst::FCMP_UGT: 4152 case FCmpInst::FCMP_UNE: { 4153 KnownFPClass KnownClass = computeLHSClass(Interested); 4154 4155 // (X >= 0) implies (X > C) when (C < 0) 4156 if (KnownClass.cannotBeOrderedLessThanZero()) 4157 return getTrue(RetTy); 4158 break; 4159 } 4160 case FCmpInst::FCMP_OEQ: 4161 case FCmpInst::FCMP_OLE: 4162 case FCmpInst::FCMP_OLT: { 4163 KnownFPClass KnownClass = computeLHSClass(Interested); 4164 4165 // (X >= 0) implies !(X < C) when (C < 0) 4166 if (KnownClass.cannotBeOrderedLessThanZero()) 4167 return getFalse(RetTy); 4168 break; 4169 } 4170 default: 4171 break; 4172 } 4173 } 4174 // Check comparison of [minnum/maxnum with constant] with other constant. 4175 const APFloat *C2; 4176 if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) && 4177 *C2 < *C) || 4178 (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) && 4179 *C2 > *C)) { 4180 bool IsMaxNum = 4181 cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum; 4182 // The ordered relationship and minnum/maxnum guarantee that we do not 4183 // have NaN constants, so ordered/unordered preds are handled the same. 4184 switch (Pred) { 4185 case FCmpInst::FCMP_OEQ: 4186 case FCmpInst::FCMP_UEQ: 4187 // minnum(X, LesserC) == C --> false 4188 // maxnum(X, GreaterC) == C --> false 4189 return getFalse(RetTy); 4190 case FCmpInst::FCMP_ONE: 4191 case FCmpInst::FCMP_UNE: 4192 // minnum(X, LesserC) != C --> true 4193 // maxnum(X, GreaterC) != C --> true 4194 return getTrue(RetTy); 4195 case FCmpInst::FCMP_OGE: 4196 case FCmpInst::FCMP_UGE: 4197 case FCmpInst::FCMP_OGT: 4198 case FCmpInst::FCMP_UGT: 4199 // minnum(X, LesserC) >= C --> false 4200 // minnum(X, LesserC) > C --> false 4201 // maxnum(X, GreaterC) >= C --> true 4202 // maxnum(X, GreaterC) > C --> true 4203 return ConstantInt::get(RetTy, IsMaxNum); 4204 case FCmpInst::FCMP_OLE: 4205 case FCmpInst::FCMP_ULE: 4206 case FCmpInst::FCMP_OLT: 4207 case FCmpInst::FCMP_ULT: 4208 // minnum(X, LesserC) <= C --> true 4209 // minnum(X, LesserC) < C --> true 4210 // maxnum(X, GreaterC) <= C --> false 4211 // maxnum(X, GreaterC) < C --> false 4212 return ConstantInt::get(RetTy, !IsMaxNum); 4213 default: 4214 // TRUE/FALSE/ORD/UNO should be handled before this. 4215 llvm_unreachable("Unexpected fcmp predicate"); 4216 } 4217 } 4218 } 4219 4220 // TODO: Could fold this with above if there were a matcher which returned all 4221 // classes in a non-splat vector. 4222 if (match(RHS, m_AnyZeroFP())) { 4223 switch (Pred) { 4224 case FCmpInst::FCMP_OGE: 4225 case FCmpInst::FCMP_ULT: { 4226 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4227 if (!FMF.noNaNs()) 4228 Interested |= fcNan; 4229 4230 KnownFPClass Known = computeLHSClass(Interested); 4231 4232 // Positive or zero X >= 0.0 --> true 4233 // Positive or zero X < 0.0 --> false 4234 if ((FMF.noNaNs() || Known.isKnownNeverNaN()) && 4235 Known.cannotBeOrderedLessThanZero()) 4236 return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy); 4237 break; 4238 } 4239 case FCmpInst::FCMP_UGE: 4240 case FCmpInst::FCMP_OLT: { 4241 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4242 KnownFPClass Known = computeLHSClass(Interested); 4243 4244 // Positive or zero or nan X >= 0.0 --> true 4245 // Positive or zero or nan X < 0.0 --> false 4246 if (Known.cannotBeOrderedLessThanZero()) 4247 return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy); 4248 break; 4249 } 4250 default: 4251 break; 4252 } 4253 } 4254 4255 // If the comparison is with the result of a select instruction, check whether 4256 // comparing with either branch of the select always yields the same value. 4257 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 4258 if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 4259 return V; 4260 4261 // If the comparison is with the result of a phi instruction, check whether 4262 // doing the compare with each incoming phi value yields a common result. 4263 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 4264 if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 4265 return V; 4266 4267 return nullptr; 4268 } 4269 4270 Value *llvm::simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4271 FastMathFlags FMF, const SimplifyQuery &Q) { 4272 return ::simplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit); 4273 } 4274 4275 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 4276 const SimplifyQuery &Q, 4277 bool AllowRefinement, 4278 SmallVectorImpl<Instruction *> *DropFlags, 4279 unsigned MaxRecurse) { 4280 // Trivial replacement. 4281 if (V == Op) 4282 return RepOp; 4283 4284 if (!MaxRecurse--) 4285 return nullptr; 4286 4287 // We cannot replace a constant, and shouldn't even try. 4288 if (isa<Constant>(Op)) 4289 return nullptr; 4290 4291 auto *I = dyn_cast<Instruction>(V); 4292 if (!I) 4293 return nullptr; 4294 4295 // The arguments of a phi node might refer to a value from a previous 4296 // cycle iteration. 4297 if (isa<PHINode>(I)) 4298 return nullptr; 4299 4300 if (Op->getType()->isVectorTy()) { 4301 // For vector types, the simplification must hold per-lane, so forbid 4302 // potentially cross-lane operations like shufflevector. 4303 if (!I->getType()->isVectorTy() || isa<ShuffleVectorInst>(I) || 4304 isa<CallBase>(I)) 4305 return nullptr; 4306 } 4307 4308 // Don't fold away llvm.is.constant checks based on assumptions. 4309 if (match(I, m_Intrinsic<Intrinsic::is_constant>())) 4310 return nullptr; 4311 4312 // Replace Op with RepOp in instruction operands. 4313 SmallVector<Value *, 8> NewOps; 4314 bool AnyReplaced = false; 4315 for (Value *InstOp : I->operands()) { 4316 if (Value *NewInstOp = simplifyWithOpReplaced( 4317 InstOp, Op, RepOp, Q, AllowRefinement, DropFlags, MaxRecurse)) { 4318 NewOps.push_back(NewInstOp); 4319 AnyReplaced = InstOp != NewInstOp; 4320 } else { 4321 NewOps.push_back(InstOp); 4322 } 4323 } 4324 4325 if (!AnyReplaced) 4326 return nullptr; 4327 4328 if (!AllowRefinement) { 4329 // General InstSimplify functions may refine the result, e.g. by returning 4330 // a constant for a potentially poison value. To avoid this, implement only 4331 // a few non-refining but profitable transforms here. 4332 4333 if (auto *BO = dyn_cast<BinaryOperator>(I)) { 4334 unsigned Opcode = BO->getOpcode(); 4335 // id op x -> x, x op id -> x 4336 if (NewOps[0] == ConstantExpr::getBinOpIdentity(Opcode, I->getType())) 4337 return NewOps[1]; 4338 if (NewOps[1] == ConstantExpr::getBinOpIdentity(Opcode, I->getType(), 4339 /* RHS */ true)) 4340 return NewOps[0]; 4341 4342 // x & x -> x, x | x -> x 4343 if ((Opcode == Instruction::And || Opcode == Instruction::Or) && 4344 NewOps[0] == NewOps[1]) { 4345 // or disjoint x, x results in poison. 4346 if (auto *PDI = dyn_cast<PossiblyDisjointInst>(BO)) { 4347 if (PDI->isDisjoint()) { 4348 if (!DropFlags) 4349 return nullptr; 4350 DropFlags->push_back(BO); 4351 } 4352 } 4353 return NewOps[0]; 4354 } 4355 4356 // x - x -> 0, x ^ x -> 0. This is non-refining, because x is non-poison 4357 // by assumption and this case never wraps, so nowrap flags can be 4358 // ignored. 4359 if ((Opcode == Instruction::Sub || Opcode == Instruction::Xor) && 4360 NewOps[0] == RepOp && NewOps[1] == RepOp) 4361 return Constant::getNullValue(I->getType()); 4362 4363 // If we are substituting an absorber constant into a binop and extra 4364 // poison can't leak if we remove the select -- because both operands of 4365 // the binop are based on the same value -- then it may be safe to replace 4366 // the value with the absorber constant. Examples: 4367 // (Op == 0) ? 0 : (Op & -Op) --> Op & -Op 4368 // (Op == 0) ? 0 : (Op * (binop Op, C)) --> Op * (binop Op, C) 4369 // (Op == -1) ? -1 : (Op | (binop C, Op) --> Op | (binop C, Op) 4370 Constant *Absorber = 4371 ConstantExpr::getBinOpAbsorber(Opcode, I->getType()); 4372 if ((NewOps[0] == Absorber || NewOps[1] == Absorber) && 4373 impliesPoison(BO, Op)) 4374 return Absorber; 4375 } 4376 4377 if (isa<GetElementPtrInst>(I)) { 4378 // getelementptr x, 0 -> x. 4379 // This never returns poison, even if inbounds is set. 4380 if (NewOps.size() == 2 && match(NewOps[1], m_Zero())) 4381 return NewOps[0]; 4382 } 4383 } else { 4384 // The simplification queries below may return the original value. Consider: 4385 // %div = udiv i32 %arg, %arg2 4386 // %mul = mul nsw i32 %div, %arg2 4387 // %cmp = icmp eq i32 %mul, %arg 4388 // %sel = select i1 %cmp, i32 %div, i32 undef 4389 // Replacing %arg by %mul, %div becomes "udiv i32 %mul, %arg2", which 4390 // simplifies back to %arg. This can only happen because %mul does not 4391 // dominate %div. To ensure a consistent return value contract, we make sure 4392 // that this case returns nullptr as well. 4393 auto PreventSelfSimplify = [V](Value *Simplified) { 4394 return Simplified != V ? Simplified : nullptr; 4395 }; 4396 4397 return PreventSelfSimplify( 4398 ::simplifyInstructionWithOperands(I, NewOps, Q, MaxRecurse)); 4399 } 4400 4401 // If all operands are constant after substituting Op for RepOp then we can 4402 // constant fold the instruction. 4403 SmallVector<Constant *, 8> ConstOps; 4404 for (Value *NewOp : NewOps) { 4405 if (Constant *ConstOp = dyn_cast<Constant>(NewOp)) 4406 ConstOps.push_back(ConstOp); 4407 else 4408 return nullptr; 4409 } 4410 4411 // Consider: 4412 // %cmp = icmp eq i32 %x, 2147483647 4413 // %add = add nsw i32 %x, 1 4414 // %sel = select i1 %cmp, i32 -2147483648, i32 %add 4415 // 4416 // We can't replace %sel with %add unless we strip away the flags (which 4417 // will be done in InstCombine). 4418 // TODO: This may be unsound, because it only catches some forms of 4419 // refinement. 4420 if (!AllowRefinement) { 4421 if (canCreatePoison(cast<Operator>(I), !DropFlags)) { 4422 // abs cannot create poison if the value is known to never be int_min. 4423 if (auto *II = dyn_cast<IntrinsicInst>(I); 4424 II && II->getIntrinsicID() == Intrinsic::abs) { 4425 if (!ConstOps[0]->isNotMinSignedValue()) 4426 return nullptr; 4427 } else 4428 return nullptr; 4429 } 4430 Constant *Res = ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI); 4431 if (DropFlags && Res && I->hasPoisonGeneratingFlagsOrMetadata()) 4432 DropFlags->push_back(I); 4433 return Res; 4434 } 4435 4436 return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI); 4437 } 4438 4439 Value *llvm::simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 4440 const SimplifyQuery &Q, 4441 bool AllowRefinement, 4442 SmallVectorImpl<Instruction *> *DropFlags) { 4443 return ::simplifyWithOpReplaced(V, Op, RepOp, Q, AllowRefinement, DropFlags, 4444 RecursionLimit); 4445 } 4446 4447 /// Try to simplify a select instruction when its condition operand is an 4448 /// integer comparison where one operand of the compare is a constant. 4449 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X, 4450 const APInt *Y, bool TrueWhenUnset) { 4451 const APInt *C; 4452 4453 // (X & Y) == 0 ? X & ~Y : X --> X 4454 // (X & Y) != 0 ? X & ~Y : X --> X & ~Y 4455 if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) && 4456 *Y == ~*C) 4457 return TrueWhenUnset ? FalseVal : TrueVal; 4458 4459 // (X & Y) == 0 ? X : X & ~Y --> X & ~Y 4460 // (X & Y) != 0 ? X : X & ~Y --> X 4461 if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) && 4462 *Y == ~*C) 4463 return TrueWhenUnset ? FalseVal : TrueVal; 4464 4465 if (Y->isPowerOf2()) { 4466 // (X & Y) == 0 ? X | Y : X --> X | Y 4467 // (X & Y) != 0 ? X | Y : X --> X 4468 if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) && 4469 *Y == *C) { 4470 // We can't return the or if it has the disjoint flag. 4471 if (TrueWhenUnset && cast<PossiblyDisjointInst>(TrueVal)->isDisjoint()) 4472 return nullptr; 4473 return TrueWhenUnset ? TrueVal : FalseVal; 4474 } 4475 4476 // (X & Y) == 0 ? X : X | Y --> X 4477 // (X & Y) != 0 ? X : X | Y --> X | Y 4478 if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) && 4479 *Y == *C) { 4480 // We can't return the or if it has the disjoint flag. 4481 if (!TrueWhenUnset && cast<PossiblyDisjointInst>(FalseVal)->isDisjoint()) 4482 return nullptr; 4483 return TrueWhenUnset ? TrueVal : FalseVal; 4484 } 4485 } 4486 4487 return nullptr; 4488 } 4489 4490 static Value *simplifyCmpSelOfMaxMin(Value *CmpLHS, Value *CmpRHS, 4491 ICmpInst::Predicate Pred, Value *TVal, 4492 Value *FVal) { 4493 // Canonicalize common cmp+sel operand as CmpLHS. 4494 if (CmpRHS == TVal || CmpRHS == FVal) { 4495 std::swap(CmpLHS, CmpRHS); 4496 Pred = ICmpInst::getSwappedPredicate(Pred); 4497 } 4498 4499 // Canonicalize common cmp+sel operand as TVal. 4500 if (CmpLHS == FVal) { 4501 std::swap(TVal, FVal); 4502 Pred = ICmpInst::getInversePredicate(Pred); 4503 } 4504 4505 // A vector select may be shuffling together elements that are equivalent 4506 // based on the max/min/select relationship. 4507 Value *X = CmpLHS, *Y = CmpRHS; 4508 bool PeekedThroughSelectShuffle = false; 4509 auto *Shuf = dyn_cast<ShuffleVectorInst>(FVal); 4510 if (Shuf && Shuf->isSelect()) { 4511 if (Shuf->getOperand(0) == Y) 4512 FVal = Shuf->getOperand(1); 4513 else if (Shuf->getOperand(1) == Y) 4514 FVal = Shuf->getOperand(0); 4515 else 4516 return nullptr; 4517 PeekedThroughSelectShuffle = true; 4518 } 4519 4520 // (X pred Y) ? X : max/min(X, Y) 4521 auto *MMI = dyn_cast<MinMaxIntrinsic>(FVal); 4522 if (!MMI || TVal != X || 4523 !match(FVal, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) 4524 return nullptr; 4525 4526 // (X > Y) ? X : max(X, Y) --> max(X, Y) 4527 // (X >= Y) ? X : max(X, Y) --> max(X, Y) 4528 // (X < Y) ? X : min(X, Y) --> min(X, Y) 4529 // (X <= Y) ? X : min(X, Y) --> min(X, Y) 4530 // 4531 // The equivalence allows a vector select (shuffle) of max/min and Y. Ex: 4532 // (X > Y) ? X : (Z ? max(X, Y) : Y) 4533 // If Z is true, this reduces as above, and if Z is false: 4534 // (X > Y) ? X : Y --> max(X, Y) 4535 ICmpInst::Predicate MMPred = MMI->getPredicate(); 4536 if (MMPred == CmpInst::getStrictPredicate(Pred)) 4537 return MMI; 4538 4539 // Other transforms are not valid with a shuffle. 4540 if (PeekedThroughSelectShuffle) 4541 return nullptr; 4542 4543 // (X == Y) ? X : max/min(X, Y) --> max/min(X, Y) 4544 if (Pred == CmpInst::ICMP_EQ) 4545 return MMI; 4546 4547 // (X != Y) ? X : max/min(X, Y) --> X 4548 if (Pred == CmpInst::ICMP_NE) 4549 return X; 4550 4551 // (X < Y) ? X : max(X, Y) --> X 4552 // (X <= Y) ? X : max(X, Y) --> X 4553 // (X > Y) ? X : min(X, Y) --> X 4554 // (X >= Y) ? X : min(X, Y) --> X 4555 ICmpInst::Predicate InvPred = CmpInst::getInversePredicate(Pred); 4556 if (MMPred == CmpInst::getStrictPredicate(InvPred)) 4557 return X; 4558 4559 return nullptr; 4560 } 4561 4562 /// An alternative way to test if a bit is set or not uses sgt/slt instead of 4563 /// eq/ne. 4564 static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS, 4565 ICmpInst::Predicate Pred, 4566 Value *TrueVal, Value *FalseVal) { 4567 Value *X; 4568 APInt Mask; 4569 if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) 4570 return nullptr; 4571 4572 return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask, 4573 Pred == ICmpInst::ICMP_EQ); 4574 } 4575 4576 /// Try to simplify a select instruction when its condition operand is an 4577 /// integer equality comparison. 4578 static Value *simplifySelectWithICmpEq(Value *CmpLHS, Value *CmpRHS, 4579 Value *TrueVal, Value *FalseVal, 4580 const SimplifyQuery &Q, 4581 unsigned MaxRecurse) { 4582 if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, 4583 /* AllowRefinement */ false, 4584 /* DropFlags */ nullptr, MaxRecurse) == TrueVal) 4585 return FalseVal; 4586 if (simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, 4587 /* AllowRefinement */ true, 4588 /* DropFlags */ nullptr, MaxRecurse) == FalseVal) 4589 return FalseVal; 4590 4591 return nullptr; 4592 } 4593 4594 /// Try to simplify a select instruction when its condition operand is an 4595 /// integer comparison. 4596 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, 4597 Value *FalseVal, 4598 const SimplifyQuery &Q, 4599 unsigned MaxRecurse) { 4600 ICmpInst::Predicate Pred; 4601 Value *CmpLHS, *CmpRHS; 4602 if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS)))) 4603 return nullptr; 4604 4605 if (Value *V = simplifyCmpSelOfMaxMin(CmpLHS, CmpRHS, Pred, TrueVal, FalseVal)) 4606 return V; 4607 4608 // Canonicalize ne to eq predicate. 4609 if (Pred == ICmpInst::ICMP_NE) { 4610 Pred = ICmpInst::ICMP_EQ; 4611 std::swap(TrueVal, FalseVal); 4612 } 4613 4614 // Check for integer min/max with a limit constant: 4615 // X > MIN_INT ? X : MIN_INT --> X 4616 // X < MAX_INT ? X : MAX_INT --> X 4617 if (TrueVal->getType()->isIntOrIntVectorTy()) { 4618 Value *X, *Y; 4619 SelectPatternFlavor SPF = 4620 matchDecomposedSelectPattern(cast<ICmpInst>(CondVal), TrueVal, FalseVal, 4621 X, Y) 4622 .Flavor; 4623 if (SelectPatternResult::isMinOrMax(SPF) && Pred == getMinMaxPred(SPF)) { 4624 APInt LimitC = getMinMaxLimit(getInverseMinMaxFlavor(SPF), 4625 X->getType()->getScalarSizeInBits()); 4626 if (match(Y, m_SpecificInt(LimitC))) 4627 return X; 4628 } 4629 } 4630 4631 if (Pred == ICmpInst::ICMP_EQ && match(CmpRHS, m_Zero())) { 4632 Value *X; 4633 const APInt *Y; 4634 if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y)))) 4635 if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y, 4636 /*TrueWhenUnset=*/true)) 4637 return V; 4638 4639 // Test for a bogus zero-shift-guard-op around funnel-shift or rotate. 4640 Value *ShAmt; 4641 auto isFsh = m_CombineOr(m_FShl(m_Value(X), m_Value(), m_Value(ShAmt)), 4642 m_FShr(m_Value(), m_Value(X), m_Value(ShAmt))); 4643 // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X 4644 // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X 4645 if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt) 4646 return X; 4647 4648 // Test for a zero-shift-guard-op around rotates. These are used to 4649 // avoid UB from oversized shifts in raw IR rotate patterns, but the 4650 // intrinsics do not have that problem. 4651 // We do not allow this transform for the general funnel shift case because 4652 // that would not preserve the poison safety of the original code. 4653 auto isRotate = 4654 m_CombineOr(m_FShl(m_Value(X), m_Deferred(X), m_Value(ShAmt)), 4655 m_FShr(m_Value(X), m_Deferred(X), m_Value(ShAmt))); 4656 // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt) 4657 // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt) 4658 if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt && 4659 Pred == ICmpInst::ICMP_EQ) 4660 return FalseVal; 4661 4662 // X == 0 ? abs(X) : -abs(X) --> -abs(X) 4663 // X == 0 ? -abs(X) : abs(X) --> abs(X) 4664 if (match(TrueVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))) && 4665 match(FalseVal, m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))))) 4666 return FalseVal; 4667 if (match(TrueVal, 4668 m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) && 4669 match(FalseVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) 4670 return FalseVal; 4671 } 4672 4673 // Check for other compares that behave like bit test. 4674 if (Value *V = 4675 simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred, TrueVal, FalseVal)) 4676 return V; 4677 4678 // If we have a scalar equality comparison, then we know the value in one of 4679 // the arms of the select. See if substituting this value into the arm and 4680 // simplifying the result yields the same value as the other arm. 4681 if (Pred == ICmpInst::ICMP_EQ) { 4682 if (Value *V = simplifySelectWithICmpEq(CmpLHS, CmpRHS, TrueVal, FalseVal, 4683 Q, MaxRecurse)) 4684 return V; 4685 if (Value *V = simplifySelectWithICmpEq(CmpRHS, CmpLHS, TrueVal, FalseVal, 4686 Q, MaxRecurse)) 4687 return V; 4688 4689 Value *X; 4690 Value *Y; 4691 // select((X | Y) == 0 ? X : 0) --> 0 (commuted 2 ways) 4692 if (match(CmpLHS, m_Or(m_Value(X), m_Value(Y))) && 4693 match(CmpRHS, m_Zero())) { 4694 // (X | Y) == 0 implies X == 0 and Y == 0. 4695 if (Value *V = simplifySelectWithICmpEq(X, CmpRHS, TrueVal, FalseVal, Q, 4696 MaxRecurse)) 4697 return V; 4698 if (Value *V = simplifySelectWithICmpEq(Y, CmpRHS, TrueVal, FalseVal, Q, 4699 MaxRecurse)) 4700 return V; 4701 } 4702 4703 // select((X & Y) == -1 ? X : -1) --> -1 (commuted 2 ways) 4704 if (match(CmpLHS, m_And(m_Value(X), m_Value(Y))) && 4705 match(CmpRHS, m_AllOnes())) { 4706 // (X & Y) == -1 implies X == -1 and Y == -1. 4707 if (Value *V = simplifySelectWithICmpEq(X, CmpRHS, TrueVal, FalseVal, Q, 4708 MaxRecurse)) 4709 return V; 4710 if (Value *V = simplifySelectWithICmpEq(Y, CmpRHS, TrueVal, FalseVal, Q, 4711 MaxRecurse)) 4712 return V; 4713 } 4714 } 4715 4716 return nullptr; 4717 } 4718 4719 /// Try to simplify a select instruction when its condition operand is a 4720 /// floating-point comparison. 4721 static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F, 4722 const SimplifyQuery &Q) { 4723 FCmpInst::Predicate Pred; 4724 if (!match(Cond, m_FCmp(Pred, m_Specific(T), m_Specific(F))) && 4725 !match(Cond, m_FCmp(Pred, m_Specific(F), m_Specific(T)))) 4726 return nullptr; 4727 4728 // This transform is safe if we do not have (do not care about) -0.0 or if 4729 // at least one operand is known to not be -0.0. Otherwise, the select can 4730 // change the sign of a zero operand. 4731 bool HasNoSignedZeros = 4732 Q.CxtI && isa<FPMathOperator>(Q.CxtI) && Q.CxtI->hasNoSignedZeros(); 4733 const APFloat *C; 4734 if (HasNoSignedZeros || (match(T, m_APFloat(C)) && C->isNonZero()) || 4735 (match(F, m_APFloat(C)) && C->isNonZero())) { 4736 // (T == F) ? T : F --> F 4737 // (F == T) ? T : F --> F 4738 if (Pred == FCmpInst::FCMP_OEQ) 4739 return F; 4740 4741 // (T != F) ? T : F --> T 4742 // (F != T) ? T : F --> T 4743 if (Pred == FCmpInst::FCMP_UNE) 4744 return T; 4745 } 4746 4747 return nullptr; 4748 } 4749 4750 /// Given operands for a SelectInst, see if we can fold the result. 4751 /// If not, this returns null. 4752 static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4753 const SimplifyQuery &Q, unsigned MaxRecurse) { 4754 if (auto *CondC = dyn_cast<Constant>(Cond)) { 4755 if (auto *TrueC = dyn_cast<Constant>(TrueVal)) 4756 if (auto *FalseC = dyn_cast<Constant>(FalseVal)) 4757 if (Constant *C = ConstantFoldSelectInstruction(CondC, TrueC, FalseC)) 4758 return C; 4759 4760 // select poison, X, Y -> poison 4761 if (isa<PoisonValue>(CondC)) 4762 return PoisonValue::get(TrueVal->getType()); 4763 4764 // select undef, X, Y -> X or Y 4765 if (Q.isUndefValue(CondC)) 4766 return isa<Constant>(FalseVal) ? FalseVal : TrueVal; 4767 4768 // select true, X, Y --> X 4769 // select false, X, Y --> Y 4770 // For vectors, allow undef/poison elements in the condition to match the 4771 // defined elements, so we can eliminate the select. 4772 if (match(CondC, m_One())) 4773 return TrueVal; 4774 if (match(CondC, m_Zero())) 4775 return FalseVal; 4776 } 4777 4778 assert(Cond->getType()->isIntOrIntVectorTy(1) && 4779 "Select must have bool or bool vector condition"); 4780 assert(TrueVal->getType() == FalseVal->getType() && 4781 "Select must have same types for true/false ops"); 4782 4783 if (Cond->getType() == TrueVal->getType()) { 4784 // select i1 Cond, i1 true, i1 false --> i1 Cond 4785 if (match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt())) 4786 return Cond; 4787 4788 // (X && Y) ? X : Y --> Y (commuted 2 ways) 4789 if (match(Cond, m_c_LogicalAnd(m_Specific(TrueVal), m_Specific(FalseVal)))) 4790 return FalseVal; 4791 4792 // (X || Y) ? X : Y --> X (commuted 2 ways) 4793 if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Specific(FalseVal)))) 4794 return TrueVal; 4795 4796 // (X || Y) ? false : X --> false (commuted 2 ways) 4797 if (match(Cond, m_c_LogicalOr(m_Specific(FalseVal), m_Value())) && 4798 match(TrueVal, m_ZeroInt())) 4799 return ConstantInt::getFalse(Cond->getType()); 4800 4801 // Match patterns that end in logical-and. 4802 if (match(FalseVal, m_ZeroInt())) { 4803 // !(X || Y) && X --> false (commuted 2 ways) 4804 if (match(Cond, m_Not(m_c_LogicalOr(m_Specific(TrueVal), m_Value())))) 4805 return ConstantInt::getFalse(Cond->getType()); 4806 // X && !(X || Y) --> false (commuted 2 ways) 4807 if (match(TrueVal, m_Not(m_c_LogicalOr(m_Specific(Cond), m_Value())))) 4808 return ConstantInt::getFalse(Cond->getType()); 4809 4810 // (X || Y) && Y --> Y (commuted 2 ways) 4811 if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Value()))) 4812 return TrueVal; 4813 // Y && (X || Y) --> Y (commuted 2 ways) 4814 if (match(TrueVal, m_c_LogicalOr(m_Specific(Cond), m_Value()))) 4815 return Cond; 4816 4817 // (X || Y) && (X || !Y) --> X (commuted 8 ways) 4818 Value *X, *Y; 4819 if (match(Cond, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) && 4820 match(TrueVal, m_c_LogicalOr(m_Specific(X), m_Specific(Y)))) 4821 return X; 4822 if (match(TrueVal, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) && 4823 match(Cond, m_c_LogicalOr(m_Specific(X), m_Specific(Y)))) 4824 return X; 4825 } 4826 4827 // Match patterns that end in logical-or. 4828 if (match(TrueVal, m_One())) { 4829 // !(X && Y) || X --> true (commuted 2 ways) 4830 if (match(Cond, m_Not(m_c_LogicalAnd(m_Specific(FalseVal), m_Value())))) 4831 return ConstantInt::getTrue(Cond->getType()); 4832 // X || !(X && Y) --> true (commuted 2 ways) 4833 if (match(FalseVal, m_Not(m_c_LogicalAnd(m_Specific(Cond), m_Value())))) 4834 return ConstantInt::getTrue(Cond->getType()); 4835 4836 // (X && Y) || Y --> Y (commuted 2 ways) 4837 if (match(Cond, m_c_LogicalAnd(m_Specific(FalseVal), m_Value()))) 4838 return FalseVal; 4839 // Y || (X && Y) --> Y (commuted 2 ways) 4840 if (match(FalseVal, m_c_LogicalAnd(m_Specific(Cond), m_Value()))) 4841 return Cond; 4842 } 4843 } 4844 4845 // select ?, X, X -> X 4846 if (TrueVal == FalseVal) 4847 return TrueVal; 4848 4849 if (Cond == TrueVal) { 4850 // select i1 X, i1 X, i1 false --> X (logical-and) 4851 if (match(FalseVal, m_ZeroInt())) 4852 return Cond; 4853 // select i1 X, i1 X, i1 true --> true 4854 if (match(FalseVal, m_One())) 4855 return ConstantInt::getTrue(Cond->getType()); 4856 } 4857 if (Cond == FalseVal) { 4858 // select i1 X, i1 true, i1 X --> X (logical-or) 4859 if (match(TrueVal, m_One())) 4860 return Cond; 4861 // select i1 X, i1 false, i1 X --> false 4862 if (match(TrueVal, m_ZeroInt())) 4863 return ConstantInt::getFalse(Cond->getType()); 4864 } 4865 4866 // If the true or false value is poison, we can fold to the other value. 4867 // If the true or false value is undef, we can fold to the other value as 4868 // long as the other value isn't poison. 4869 // select ?, poison, X -> X 4870 // select ?, undef, X -> X 4871 if (isa<PoisonValue>(TrueVal) || 4872 (Q.isUndefValue(TrueVal) && impliesPoison(FalseVal, Cond))) 4873 return FalseVal; 4874 // select ?, X, poison -> X 4875 // select ?, X, undef -> X 4876 if (isa<PoisonValue>(FalseVal) || 4877 (Q.isUndefValue(FalseVal) && impliesPoison(TrueVal, Cond))) 4878 return TrueVal; 4879 4880 // Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC'' 4881 Constant *TrueC, *FalseC; 4882 if (isa<FixedVectorType>(TrueVal->getType()) && 4883 match(TrueVal, m_Constant(TrueC)) && 4884 match(FalseVal, m_Constant(FalseC))) { 4885 unsigned NumElts = 4886 cast<FixedVectorType>(TrueC->getType())->getNumElements(); 4887 SmallVector<Constant *, 16> NewC; 4888 for (unsigned i = 0; i != NumElts; ++i) { 4889 // Bail out on incomplete vector constants. 4890 Constant *TEltC = TrueC->getAggregateElement(i); 4891 Constant *FEltC = FalseC->getAggregateElement(i); 4892 if (!TEltC || !FEltC) 4893 break; 4894 4895 // If the elements match (undef or not), that value is the result. If only 4896 // one element is undef, choose the defined element as the safe result. 4897 if (TEltC == FEltC) 4898 NewC.push_back(TEltC); 4899 else if (isa<PoisonValue>(TEltC) || 4900 (Q.isUndefValue(TEltC) && isGuaranteedNotToBePoison(FEltC))) 4901 NewC.push_back(FEltC); 4902 else if (isa<PoisonValue>(FEltC) || 4903 (Q.isUndefValue(FEltC) && isGuaranteedNotToBePoison(TEltC))) 4904 NewC.push_back(TEltC); 4905 else 4906 break; 4907 } 4908 if (NewC.size() == NumElts) 4909 return ConstantVector::get(NewC); 4910 } 4911 4912 if (Value *V = 4913 simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse)) 4914 return V; 4915 4916 if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q)) 4917 return V; 4918 4919 if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal)) 4920 return V; 4921 4922 std::optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL); 4923 if (Imp) 4924 return *Imp ? TrueVal : FalseVal; 4925 4926 return nullptr; 4927 } 4928 4929 Value *llvm::simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4930 const SimplifyQuery &Q) { 4931 return ::simplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit); 4932 } 4933 4934 /// Given operands for an GetElementPtrInst, see if we can fold the result. 4935 /// If not, this returns null. 4936 static Value *simplifyGEPInst(Type *SrcTy, Value *Ptr, 4937 ArrayRef<Value *> Indices, bool InBounds, 4938 const SimplifyQuery &Q, unsigned) { 4939 // The type of the GEP pointer operand. 4940 unsigned AS = 4941 cast<PointerType>(Ptr->getType()->getScalarType())->getAddressSpace(); 4942 4943 // getelementptr P -> P. 4944 if (Indices.empty()) 4945 return Ptr; 4946 4947 // Compute the (pointer) type returned by the GEP instruction. 4948 Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Indices); 4949 Type *GEPTy = Ptr->getType(); 4950 if (!GEPTy->isVectorTy()) { 4951 for (Value *Op : Indices) { 4952 // If one of the operands is a vector, the result type is a vector of 4953 // pointers. All vector operands must have the same number of elements. 4954 if (VectorType *VT = dyn_cast<VectorType>(Op->getType())) { 4955 GEPTy = VectorType::get(GEPTy, VT->getElementCount()); 4956 break; 4957 } 4958 } 4959 } 4960 4961 // All-zero GEP is a no-op, unless it performs a vector splat. 4962 if (Ptr->getType() == GEPTy && 4963 all_of(Indices, [](const auto *V) { return match(V, m_Zero()); })) 4964 return Ptr; 4965 4966 // getelementptr poison, idx -> poison 4967 // getelementptr baseptr, poison -> poison 4968 if (isa<PoisonValue>(Ptr) || 4969 any_of(Indices, [](const auto *V) { return isa<PoisonValue>(V); })) 4970 return PoisonValue::get(GEPTy); 4971 4972 // getelementptr undef, idx -> undef 4973 if (Q.isUndefValue(Ptr)) 4974 return UndefValue::get(GEPTy); 4975 4976 bool IsScalableVec = 4977 SrcTy->isScalableTy() || any_of(Indices, [](const Value *V) { 4978 return isa<ScalableVectorType>(V->getType()); 4979 }); 4980 4981 if (Indices.size() == 1) { 4982 Type *Ty = SrcTy; 4983 if (!IsScalableVec && Ty->isSized()) { 4984 Value *P; 4985 uint64_t C; 4986 uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty); 4987 // getelementptr P, N -> P if P points to a type of zero size. 4988 if (TyAllocSize == 0 && Ptr->getType() == GEPTy) 4989 return Ptr; 4990 4991 // The following transforms are only safe if the ptrtoint cast 4992 // doesn't truncate the pointers. 4993 if (Indices[0]->getType()->getScalarSizeInBits() == 4994 Q.DL.getPointerSizeInBits(AS)) { 4995 auto CanSimplify = [GEPTy, &P, Ptr]() -> bool { 4996 return P->getType() == GEPTy && 4997 getUnderlyingObject(P) == getUnderlyingObject(Ptr); 4998 }; 4999 // getelementptr V, (sub P, V) -> P if P points to a type of size 1. 5000 if (TyAllocSize == 1 && 5001 match(Indices[0], 5002 m_Sub(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Specific(Ptr)))) && 5003 CanSimplify()) 5004 return P; 5005 5006 // getelementptr V, (ashr (sub P, V), C) -> P if P points to a type of 5007 // size 1 << C. 5008 if (match(Indices[0], m_AShr(m_Sub(m_PtrToInt(m_Value(P)), 5009 m_PtrToInt(m_Specific(Ptr))), 5010 m_ConstantInt(C))) && 5011 TyAllocSize == 1ULL << C && CanSimplify()) 5012 return P; 5013 5014 // getelementptr V, (sdiv (sub P, V), C) -> P if P points to a type of 5015 // size C. 5016 if (match(Indices[0], m_SDiv(m_Sub(m_PtrToInt(m_Value(P)), 5017 m_PtrToInt(m_Specific(Ptr))), 5018 m_SpecificInt(TyAllocSize))) && 5019 CanSimplify()) 5020 return P; 5021 } 5022 } 5023 } 5024 5025 if (!IsScalableVec && Q.DL.getTypeAllocSize(LastType) == 1 && 5026 all_of(Indices.drop_back(1), 5027 [](Value *Idx) { return match(Idx, m_Zero()); })) { 5028 unsigned IdxWidth = 5029 Q.DL.getIndexSizeInBits(Ptr->getType()->getPointerAddressSpace()); 5030 if (Q.DL.getTypeSizeInBits(Indices.back()->getType()) == IdxWidth) { 5031 APInt BasePtrOffset(IdxWidth, 0); 5032 Value *StrippedBasePtr = 5033 Ptr->stripAndAccumulateInBoundsConstantOffsets(Q.DL, BasePtrOffset); 5034 5035 // Avoid creating inttoptr of zero here: While LLVMs treatment of 5036 // inttoptr is generally conservative, this particular case is folded to 5037 // a null pointer, which will have incorrect provenance. 5038 5039 // gep (gep V, C), (sub 0, V) -> C 5040 if (match(Indices.back(), 5041 m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr)))) && 5042 !BasePtrOffset.isZero()) { 5043 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset); 5044 return ConstantExpr::getIntToPtr(CI, GEPTy); 5045 } 5046 // gep (gep V, C), (xor V, -1) -> C-1 5047 if (match(Indices.back(), 5048 m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes())) && 5049 !BasePtrOffset.isOne()) { 5050 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1); 5051 return ConstantExpr::getIntToPtr(CI, GEPTy); 5052 } 5053 } 5054 } 5055 5056 // Check to see if this is constant foldable. 5057 if (!isa<Constant>(Ptr) || 5058 !all_of(Indices, [](Value *V) { return isa<Constant>(V); })) 5059 return nullptr; 5060 5061 if (!ConstantExpr::isSupportedGetElementPtr(SrcTy)) 5062 return ConstantFoldGetElementPtr(SrcTy, cast<Constant>(Ptr), InBounds, 5063 std::nullopt, Indices); 5064 5065 auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ptr), Indices, 5066 InBounds); 5067 return ConstantFoldConstant(CE, Q.DL); 5068 } 5069 5070 Value *llvm::simplifyGEPInst(Type *SrcTy, Value *Ptr, ArrayRef<Value *> Indices, 5071 bool InBounds, const SimplifyQuery &Q) { 5072 return ::simplifyGEPInst(SrcTy, Ptr, Indices, InBounds, Q, RecursionLimit); 5073 } 5074 5075 /// Given operands for an InsertValueInst, see if we can fold the result. 5076 /// If not, this returns null. 5077 static Value *simplifyInsertValueInst(Value *Agg, Value *Val, 5078 ArrayRef<unsigned> Idxs, 5079 const SimplifyQuery &Q, unsigned) { 5080 if (Constant *CAgg = dyn_cast<Constant>(Agg)) 5081 if (Constant *CVal = dyn_cast<Constant>(Val)) 5082 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); 5083 5084 // insertvalue x, poison, n -> x 5085 // insertvalue x, undef, n -> x if x cannot be poison 5086 if (isa<PoisonValue>(Val) || 5087 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Agg))) 5088 return Agg; 5089 5090 // insertvalue x, (extractvalue y, n), n 5091 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) 5092 if (EV->getAggregateOperand()->getType() == Agg->getType() && 5093 EV->getIndices() == Idxs) { 5094 // insertvalue poison, (extractvalue y, n), n -> y 5095 // insertvalue undef, (extractvalue y, n), n -> y if y cannot be poison 5096 if (isa<PoisonValue>(Agg) || 5097 (Q.isUndefValue(Agg) && 5098 isGuaranteedNotToBePoison(EV->getAggregateOperand()))) 5099 return EV->getAggregateOperand(); 5100 5101 // insertvalue y, (extractvalue y, n), n -> y 5102 if (Agg == EV->getAggregateOperand()) 5103 return Agg; 5104 } 5105 5106 return nullptr; 5107 } 5108 5109 Value *llvm::simplifyInsertValueInst(Value *Agg, Value *Val, 5110 ArrayRef<unsigned> Idxs, 5111 const SimplifyQuery &Q) { 5112 return ::simplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit); 5113 } 5114 5115 Value *llvm::simplifyInsertElementInst(Value *Vec, Value *Val, Value *Idx, 5116 const SimplifyQuery &Q) { 5117 // Try to constant fold. 5118 auto *VecC = dyn_cast<Constant>(Vec); 5119 auto *ValC = dyn_cast<Constant>(Val); 5120 auto *IdxC = dyn_cast<Constant>(Idx); 5121 if (VecC && ValC && IdxC) 5122 return ConstantExpr::getInsertElement(VecC, ValC, IdxC); 5123 5124 // For fixed-length vector, fold into poison if index is out of bounds. 5125 if (auto *CI = dyn_cast<ConstantInt>(Idx)) { 5126 if (isa<FixedVectorType>(Vec->getType()) && 5127 CI->uge(cast<FixedVectorType>(Vec->getType())->getNumElements())) 5128 return PoisonValue::get(Vec->getType()); 5129 } 5130 5131 // If index is undef, it might be out of bounds (see above case) 5132 if (Q.isUndefValue(Idx)) 5133 return PoisonValue::get(Vec->getType()); 5134 5135 // If the scalar is poison, or it is undef and there is no risk of 5136 // propagating poison from the vector value, simplify to the vector value. 5137 if (isa<PoisonValue>(Val) || 5138 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Vec))) 5139 return Vec; 5140 5141 // If we are extracting a value from a vector, then inserting it into the same 5142 // place, that's the input vector: 5143 // insertelt Vec, (extractelt Vec, Idx), Idx --> Vec 5144 if (match(Val, m_ExtractElt(m_Specific(Vec), m_Specific(Idx)))) 5145 return Vec; 5146 5147 return nullptr; 5148 } 5149 5150 /// Given operands for an ExtractValueInst, see if we can fold the result. 5151 /// If not, this returns null. 5152 static Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 5153 const SimplifyQuery &, unsigned) { 5154 if (auto *CAgg = dyn_cast<Constant>(Agg)) 5155 return ConstantFoldExtractValueInstruction(CAgg, Idxs); 5156 5157 // extractvalue x, (insertvalue y, elt, n), n -> elt 5158 unsigned NumIdxs = Idxs.size(); 5159 for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr; 5160 IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) { 5161 ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices(); 5162 unsigned NumInsertValueIdxs = InsertValueIdxs.size(); 5163 unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs); 5164 if (InsertValueIdxs.slice(0, NumCommonIdxs) == 5165 Idxs.slice(0, NumCommonIdxs)) { 5166 if (NumIdxs == NumInsertValueIdxs) 5167 return IVI->getInsertedValueOperand(); 5168 break; 5169 } 5170 } 5171 5172 return nullptr; 5173 } 5174 5175 Value *llvm::simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 5176 const SimplifyQuery &Q) { 5177 return ::simplifyExtractValueInst(Agg, Idxs, Q, RecursionLimit); 5178 } 5179 5180 /// Given operands for an ExtractElementInst, see if we can fold the result. 5181 /// If not, this returns null. 5182 static Value *simplifyExtractElementInst(Value *Vec, Value *Idx, 5183 const SimplifyQuery &Q, unsigned) { 5184 auto *VecVTy = cast<VectorType>(Vec->getType()); 5185 if (auto *CVec = dyn_cast<Constant>(Vec)) { 5186 if (auto *CIdx = dyn_cast<Constant>(Idx)) 5187 return ConstantExpr::getExtractElement(CVec, CIdx); 5188 5189 if (Q.isUndefValue(Vec)) 5190 return UndefValue::get(VecVTy->getElementType()); 5191 } 5192 5193 // An undef extract index can be arbitrarily chosen to be an out-of-range 5194 // index value, which would result in the instruction being poison. 5195 if (Q.isUndefValue(Idx)) 5196 return PoisonValue::get(VecVTy->getElementType()); 5197 5198 // If extracting a specified index from the vector, see if we can recursively 5199 // find a previously computed scalar that was inserted into the vector. 5200 if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) { 5201 // For fixed-length vector, fold into undef if index is out of bounds. 5202 unsigned MinNumElts = VecVTy->getElementCount().getKnownMinValue(); 5203 if (isa<FixedVectorType>(VecVTy) && IdxC->getValue().uge(MinNumElts)) 5204 return PoisonValue::get(VecVTy->getElementType()); 5205 // Handle case where an element is extracted from a splat. 5206 if (IdxC->getValue().ult(MinNumElts)) 5207 if (auto *Splat = getSplatValue(Vec)) 5208 return Splat; 5209 if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue())) 5210 return Elt; 5211 } else { 5212 // extractelt x, (insertelt y, elt, n), n -> elt 5213 // If the possibly-variable indices are trivially known to be equal 5214 // (because they are the same operand) then use the value that was 5215 // inserted directly. 5216 auto *IE = dyn_cast<InsertElementInst>(Vec); 5217 if (IE && IE->getOperand(2) == Idx) 5218 return IE->getOperand(1); 5219 5220 // The index is not relevant if our vector is a splat. 5221 if (Value *Splat = getSplatValue(Vec)) 5222 return Splat; 5223 } 5224 return nullptr; 5225 } 5226 5227 Value *llvm::simplifyExtractElementInst(Value *Vec, Value *Idx, 5228 const SimplifyQuery &Q) { 5229 return ::simplifyExtractElementInst(Vec, Idx, Q, RecursionLimit); 5230 } 5231 5232 /// See if we can fold the given phi. If not, returns null. 5233 static Value *simplifyPHINode(PHINode *PN, ArrayRef<Value *> IncomingValues, 5234 const SimplifyQuery &Q) { 5235 // WARNING: no matter how worthwhile it may seem, we can not perform PHI CSE 5236 // here, because the PHI we may succeed simplifying to was not 5237 // def-reachable from the original PHI! 5238 5239 // If all of the PHI's incoming values are the same then replace the PHI node 5240 // with the common value. 5241 Value *CommonValue = nullptr; 5242 bool HasUndefInput = false; 5243 for (Value *Incoming : IncomingValues) { 5244 // If the incoming value is the phi node itself, it can safely be skipped. 5245 if (Incoming == PN) 5246 continue; 5247 if (Q.isUndefValue(Incoming)) { 5248 // Remember that we saw an undef value, but otherwise ignore them. 5249 HasUndefInput = true; 5250 continue; 5251 } 5252 if (CommonValue && Incoming != CommonValue) 5253 return nullptr; // Not the same, bail out. 5254 CommonValue = Incoming; 5255 } 5256 5257 // If CommonValue is null then all of the incoming values were either undef or 5258 // equal to the phi node itself. 5259 if (!CommonValue) 5260 return UndefValue::get(PN->getType()); 5261 5262 if (HasUndefInput) { 5263 // If we have a PHI node like phi(X, undef, X), where X is defined by some 5264 // instruction, we cannot return X as the result of the PHI node unless it 5265 // dominates the PHI block. 5266 return valueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr; 5267 } 5268 5269 return CommonValue; 5270 } 5271 5272 static Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 5273 const SimplifyQuery &Q, unsigned MaxRecurse) { 5274 if (auto *C = dyn_cast<Constant>(Op)) 5275 return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL); 5276 5277 if (auto *CI = dyn_cast<CastInst>(Op)) { 5278 auto *Src = CI->getOperand(0); 5279 Type *SrcTy = Src->getType(); 5280 Type *MidTy = CI->getType(); 5281 Type *DstTy = Ty; 5282 if (Src->getType() == Ty) { 5283 auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode()); 5284 auto SecondOp = static_cast<Instruction::CastOps>(CastOpc); 5285 Type *SrcIntPtrTy = 5286 SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr; 5287 Type *MidIntPtrTy = 5288 MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr; 5289 Type *DstIntPtrTy = 5290 DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr; 5291 if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy, 5292 SrcIntPtrTy, MidIntPtrTy, 5293 DstIntPtrTy) == Instruction::BitCast) 5294 return Src; 5295 } 5296 } 5297 5298 // bitcast x -> x 5299 if (CastOpc == Instruction::BitCast) 5300 if (Op->getType() == Ty) 5301 return Op; 5302 5303 return nullptr; 5304 } 5305 5306 Value *llvm::simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 5307 const SimplifyQuery &Q) { 5308 return ::simplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit); 5309 } 5310 5311 /// For the given destination element of a shuffle, peek through shuffles to 5312 /// match a root vector source operand that contains that element in the same 5313 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s). 5314 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1, 5315 int MaskVal, Value *RootVec, 5316 unsigned MaxRecurse) { 5317 if (!MaxRecurse--) 5318 return nullptr; 5319 5320 // Bail out if any mask value is undefined. That kind of shuffle may be 5321 // simplified further based on demanded bits or other folds. 5322 if (MaskVal == -1) 5323 return nullptr; 5324 5325 // The mask value chooses which source operand we need to look at next. 5326 int InVecNumElts = cast<FixedVectorType>(Op0->getType())->getNumElements(); 5327 int RootElt = MaskVal; 5328 Value *SourceOp = Op0; 5329 if (MaskVal >= InVecNumElts) { 5330 RootElt = MaskVal - InVecNumElts; 5331 SourceOp = Op1; 5332 } 5333 5334 // If the source operand is a shuffle itself, look through it to find the 5335 // matching root vector. 5336 if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) { 5337 return foldIdentityShuffles( 5338 DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1), 5339 SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse); 5340 } 5341 5342 // TODO: Look through bitcasts? What if the bitcast changes the vector element 5343 // size? 5344 5345 // The source operand is not a shuffle. Initialize the root vector value for 5346 // this shuffle if that has not been done yet. 5347 if (!RootVec) 5348 RootVec = SourceOp; 5349 5350 // Give up as soon as a source operand does not match the existing root value. 5351 if (RootVec != SourceOp) 5352 return nullptr; 5353 5354 // The element must be coming from the same lane in the source vector 5355 // (although it may have crossed lanes in intermediate shuffles). 5356 if (RootElt != DestElt) 5357 return nullptr; 5358 5359 return RootVec; 5360 } 5361 5362 static Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1, 5363 ArrayRef<int> Mask, Type *RetTy, 5364 const SimplifyQuery &Q, 5365 unsigned MaxRecurse) { 5366 if (all_of(Mask, [](int Elem) { return Elem == PoisonMaskElem; })) 5367 return PoisonValue::get(RetTy); 5368 5369 auto *InVecTy = cast<VectorType>(Op0->getType()); 5370 unsigned MaskNumElts = Mask.size(); 5371 ElementCount InVecEltCount = InVecTy->getElementCount(); 5372 5373 bool Scalable = InVecEltCount.isScalable(); 5374 5375 SmallVector<int, 32> Indices; 5376 Indices.assign(Mask.begin(), Mask.end()); 5377 5378 // Canonicalization: If mask does not select elements from an input vector, 5379 // replace that input vector with poison. 5380 if (!Scalable) { 5381 bool MaskSelects0 = false, MaskSelects1 = false; 5382 unsigned InVecNumElts = InVecEltCount.getKnownMinValue(); 5383 for (unsigned i = 0; i != MaskNumElts; ++i) { 5384 if (Indices[i] == -1) 5385 continue; 5386 if ((unsigned)Indices[i] < InVecNumElts) 5387 MaskSelects0 = true; 5388 else 5389 MaskSelects1 = true; 5390 } 5391 if (!MaskSelects0) 5392 Op0 = PoisonValue::get(InVecTy); 5393 if (!MaskSelects1) 5394 Op1 = PoisonValue::get(InVecTy); 5395 } 5396 5397 auto *Op0Const = dyn_cast<Constant>(Op0); 5398 auto *Op1Const = dyn_cast<Constant>(Op1); 5399 5400 // If all operands are constant, constant fold the shuffle. This 5401 // transformation depends on the value of the mask which is not known at 5402 // compile time for scalable vectors 5403 if (Op0Const && Op1Const) 5404 return ConstantExpr::getShuffleVector(Op0Const, Op1Const, Mask); 5405 5406 // Canonicalization: if only one input vector is constant, it shall be the 5407 // second one. This transformation depends on the value of the mask which 5408 // is not known at compile time for scalable vectors 5409 if (!Scalable && Op0Const && !Op1Const) { 5410 std::swap(Op0, Op1); 5411 ShuffleVectorInst::commuteShuffleMask(Indices, 5412 InVecEltCount.getKnownMinValue()); 5413 } 5414 5415 // A splat of an inserted scalar constant becomes a vector constant: 5416 // shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...> 5417 // NOTE: We may have commuted above, so analyze the updated Indices, not the 5418 // original mask constant. 5419 // NOTE: This transformation depends on the value of the mask which is not 5420 // known at compile time for scalable vectors 5421 Constant *C; 5422 ConstantInt *IndexC; 5423 if (!Scalable && match(Op0, m_InsertElt(m_Value(), m_Constant(C), 5424 m_ConstantInt(IndexC)))) { 5425 // Match a splat shuffle mask of the insert index allowing undef elements. 5426 int InsertIndex = IndexC->getZExtValue(); 5427 if (all_of(Indices, [InsertIndex](int MaskElt) { 5428 return MaskElt == InsertIndex || MaskElt == -1; 5429 })) { 5430 assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat"); 5431 5432 // Shuffle mask poisons become poison constant result elements. 5433 SmallVector<Constant *, 16> VecC(MaskNumElts, C); 5434 for (unsigned i = 0; i != MaskNumElts; ++i) 5435 if (Indices[i] == -1) 5436 VecC[i] = PoisonValue::get(C->getType()); 5437 return ConstantVector::get(VecC); 5438 } 5439 } 5440 5441 // A shuffle of a splat is always the splat itself. Legal if the shuffle's 5442 // value type is same as the input vectors' type. 5443 if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0)) 5444 if (Q.isUndefValue(Op1) && RetTy == InVecTy && 5445 all_equal(OpShuf->getShuffleMask())) 5446 return Op0; 5447 5448 // All remaining transformation depend on the value of the mask, which is 5449 // not known at compile time for scalable vectors. 5450 if (Scalable) 5451 return nullptr; 5452 5453 // Don't fold a shuffle with undef mask elements. This may get folded in a 5454 // better way using demanded bits or other analysis. 5455 // TODO: Should we allow this? 5456 if (is_contained(Indices, -1)) 5457 return nullptr; 5458 5459 // Check if every element of this shuffle can be mapped back to the 5460 // corresponding element of a single root vector. If so, we don't need this 5461 // shuffle. This handles simple identity shuffles as well as chains of 5462 // shuffles that may widen/narrow and/or move elements across lanes and back. 5463 Value *RootVec = nullptr; 5464 for (unsigned i = 0; i != MaskNumElts; ++i) { 5465 // Note that recursion is limited for each vector element, so if any element 5466 // exceeds the limit, this will fail to simplify. 5467 RootVec = 5468 foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse); 5469 5470 // We can't replace a widening/narrowing shuffle with one of its operands. 5471 if (!RootVec || RootVec->getType() != RetTy) 5472 return nullptr; 5473 } 5474 return RootVec; 5475 } 5476 5477 /// Given operands for a ShuffleVectorInst, fold the result or return null. 5478 Value *llvm::simplifyShuffleVectorInst(Value *Op0, Value *Op1, 5479 ArrayRef<int> Mask, Type *RetTy, 5480 const SimplifyQuery &Q) { 5481 return ::simplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit); 5482 } 5483 5484 static Constant *foldConstant(Instruction::UnaryOps Opcode, Value *&Op, 5485 const SimplifyQuery &Q) { 5486 if (auto *C = dyn_cast<Constant>(Op)) 5487 return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL); 5488 return nullptr; 5489 } 5490 5491 /// Given the operand for an FNeg, see if we can fold the result. If not, this 5492 /// returns null. 5493 static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, 5494 const SimplifyQuery &Q, unsigned MaxRecurse) { 5495 if (Constant *C = foldConstant(Instruction::FNeg, Op, Q)) 5496 return C; 5497 5498 Value *X; 5499 // fneg (fneg X) ==> X 5500 if (match(Op, m_FNeg(m_Value(X)))) 5501 return X; 5502 5503 return nullptr; 5504 } 5505 5506 Value *llvm::simplifyFNegInst(Value *Op, FastMathFlags FMF, 5507 const SimplifyQuery &Q) { 5508 return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit); 5509 } 5510 5511 /// Try to propagate existing NaN values when possible. If not, replace the 5512 /// constant or elements in the constant with a canonical NaN. 5513 static Constant *propagateNaN(Constant *In) { 5514 Type *Ty = In->getType(); 5515 if (auto *VecTy = dyn_cast<FixedVectorType>(Ty)) { 5516 unsigned NumElts = VecTy->getNumElements(); 5517 SmallVector<Constant *, 32> NewC(NumElts); 5518 for (unsigned i = 0; i != NumElts; ++i) { 5519 Constant *EltC = In->getAggregateElement(i); 5520 // Poison elements propagate. NaN propagates except signaling is quieted. 5521 // Replace unknown or undef elements with canonical NaN. 5522 if (EltC && isa<PoisonValue>(EltC)) 5523 NewC[i] = EltC; 5524 else if (EltC && EltC->isNaN()) 5525 NewC[i] = ConstantFP::get( 5526 EltC->getType(), cast<ConstantFP>(EltC)->getValue().makeQuiet()); 5527 else 5528 NewC[i] = ConstantFP::getNaN(VecTy->getElementType()); 5529 } 5530 return ConstantVector::get(NewC); 5531 } 5532 5533 // If it is not a fixed vector, but not a simple NaN either, return a 5534 // canonical NaN. 5535 if (!In->isNaN()) 5536 return ConstantFP::getNaN(Ty); 5537 5538 // If we known this is a NaN, and it's scalable vector, we must have a splat 5539 // on our hands. Grab that before splatting a QNaN constant. 5540 if (isa<ScalableVectorType>(Ty)) { 5541 auto *Splat = In->getSplatValue(); 5542 assert(Splat && Splat->isNaN() && 5543 "Found a scalable-vector NaN but not a splat"); 5544 In = Splat; 5545 } 5546 5547 // Propagate an existing QNaN constant. If it is an SNaN, make it quiet, but 5548 // preserve the sign/payload. 5549 return ConstantFP::get(Ty, cast<ConstantFP>(In)->getValue().makeQuiet()); 5550 } 5551 5552 /// Perform folds that are common to any floating-point operation. This implies 5553 /// transforms based on poison/undef/NaN because the operation itself makes no 5554 /// difference to the result. 5555 static Constant *simplifyFPOp(ArrayRef<Value *> Ops, FastMathFlags FMF, 5556 const SimplifyQuery &Q, 5557 fp::ExceptionBehavior ExBehavior, 5558 RoundingMode Rounding) { 5559 // Poison is independent of anything else. It always propagates from an 5560 // operand to a math result. 5561 if (any_of(Ops, [](Value *V) { return match(V, m_Poison()); })) 5562 return PoisonValue::get(Ops[0]->getType()); 5563 5564 for (Value *V : Ops) { 5565 bool IsNan = match(V, m_NaN()); 5566 bool IsInf = match(V, m_Inf()); 5567 bool IsUndef = Q.isUndefValue(V); 5568 5569 // If this operation has 'nnan' or 'ninf' and at least 1 disallowed operand 5570 // (an undef operand can be chosen to be Nan/Inf), then the result of 5571 // this operation is poison. 5572 if (FMF.noNaNs() && (IsNan || IsUndef)) 5573 return PoisonValue::get(V->getType()); 5574 if (FMF.noInfs() && (IsInf || IsUndef)) 5575 return PoisonValue::get(V->getType()); 5576 5577 if (isDefaultFPEnvironment(ExBehavior, Rounding)) { 5578 // Undef does not propagate because undef means that all bits can take on 5579 // any value. If this is undef * NaN for example, then the result values 5580 // (at least the exponent bits) are limited. Assume the undef is a 5581 // canonical NaN and propagate that. 5582 if (IsUndef) 5583 return ConstantFP::getNaN(V->getType()); 5584 if (IsNan) 5585 return propagateNaN(cast<Constant>(V)); 5586 } else if (ExBehavior != fp::ebStrict) { 5587 if (IsNan) 5588 return propagateNaN(cast<Constant>(V)); 5589 } 5590 } 5591 return nullptr; 5592 } 5593 5594 /// Given operands for an FAdd, see if we can fold the result. If not, this 5595 /// returns null. 5596 static Value * 5597 simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5598 const SimplifyQuery &Q, unsigned MaxRecurse, 5599 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5600 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5601 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5602 if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q)) 5603 return C; 5604 5605 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5606 return C; 5607 5608 // fadd X, -0 ==> X 5609 // With strict/constrained FP, we have these possible edge cases that do 5610 // not simplify to Op0: 5611 // fadd SNaN, -0.0 --> QNaN 5612 // fadd +0.0, -0.0 --> -0.0 (but only with round toward negative) 5613 if (canIgnoreSNaN(ExBehavior, FMF) && 5614 (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) || 5615 FMF.noSignedZeros())) 5616 if (match(Op1, m_NegZeroFP())) 5617 return Op0; 5618 5619 // fadd X, 0 ==> X, when we know X is not -0 5620 if (canIgnoreSNaN(ExBehavior, FMF)) 5621 if (match(Op1, m_PosZeroFP()) && 5622 (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q.DL, Q.TLI))) 5623 return Op0; 5624 5625 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5626 return nullptr; 5627 5628 if (FMF.noNaNs()) { 5629 // With nnan: X + {+/-}Inf --> {+/-}Inf 5630 if (match(Op1, m_Inf())) 5631 return Op1; 5632 5633 // With nnan: -X + X --> 0.0 (and commuted variant) 5634 // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN. 5635 // Negative zeros are allowed because we always end up with positive zero: 5636 // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 5637 // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 5638 // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0 5639 // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0 5640 if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || 5641 match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))) 5642 return ConstantFP::getZero(Op0->getType()); 5643 5644 if (match(Op0, m_FNeg(m_Specific(Op1))) || 5645 match(Op1, m_FNeg(m_Specific(Op0)))) 5646 return ConstantFP::getZero(Op0->getType()); 5647 } 5648 5649 // (X - Y) + Y --> X 5650 // Y + (X - Y) --> X 5651 Value *X; 5652 if (FMF.noSignedZeros() && FMF.allowReassoc() && 5653 (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) || 5654 match(Op1, m_FSub(m_Value(X), m_Specific(Op0))))) 5655 return X; 5656 5657 return nullptr; 5658 } 5659 5660 /// Given operands for an FSub, see if we can fold the result. If not, this 5661 /// returns null. 5662 static Value * 5663 simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5664 const SimplifyQuery &Q, unsigned MaxRecurse, 5665 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5666 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5667 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5668 if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q)) 5669 return C; 5670 5671 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5672 return C; 5673 5674 // fsub X, +0 ==> X 5675 if (canIgnoreSNaN(ExBehavior, FMF) && 5676 (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) || 5677 FMF.noSignedZeros())) 5678 if (match(Op1, m_PosZeroFP())) 5679 return Op0; 5680 5681 // fsub X, -0 ==> X, when we know X is not -0 5682 if (canIgnoreSNaN(ExBehavior, FMF)) 5683 if (match(Op1, m_NegZeroFP()) && 5684 (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q.DL, Q.TLI))) 5685 return Op0; 5686 5687 // fsub -0.0, (fsub -0.0, X) ==> X 5688 // fsub -0.0, (fneg X) ==> X 5689 Value *X; 5690 if (canIgnoreSNaN(ExBehavior, FMF)) 5691 if (match(Op0, m_NegZeroFP()) && match(Op1, m_FNeg(m_Value(X)))) 5692 return X; 5693 5694 // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored. 5695 // fsub 0.0, (fneg X) ==> X if signed zeros are ignored. 5696 if (canIgnoreSNaN(ExBehavior, FMF)) 5697 if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) && 5698 (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) || 5699 match(Op1, m_FNeg(m_Value(X))))) 5700 return X; 5701 5702 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5703 return nullptr; 5704 5705 if (FMF.noNaNs()) { 5706 // fsub nnan x, x ==> 0.0 5707 if (Op0 == Op1) 5708 return Constant::getNullValue(Op0->getType()); 5709 5710 // With nnan: {+/-}Inf - X --> {+/-}Inf 5711 if (match(Op0, m_Inf())) 5712 return Op0; 5713 5714 // With nnan: X - {+/-}Inf --> {-/+}Inf 5715 if (match(Op1, m_Inf())) 5716 return foldConstant(Instruction::FNeg, Op1, Q); 5717 } 5718 5719 // Y - (Y - X) --> X 5720 // (X + Y) - Y --> X 5721 if (FMF.noSignedZeros() && FMF.allowReassoc() && 5722 (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) || 5723 match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X))))) 5724 return X; 5725 5726 return nullptr; 5727 } 5728 5729 static Value *simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 5730 const SimplifyQuery &Q, unsigned MaxRecurse, 5731 fp::ExceptionBehavior ExBehavior, 5732 RoundingMode Rounding) { 5733 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5734 return C; 5735 5736 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5737 return nullptr; 5738 5739 // Canonicalize special constants as operand 1. 5740 if (match(Op0, m_FPOne()) || match(Op0, m_AnyZeroFP())) 5741 std::swap(Op0, Op1); 5742 5743 // X * 1.0 --> X 5744 if (match(Op1, m_FPOne())) 5745 return Op0; 5746 5747 if (match(Op1, m_AnyZeroFP())) { 5748 // X * 0.0 --> 0.0 (with nnan and nsz) 5749 if (FMF.noNaNs() && FMF.noSignedZeros()) 5750 return ConstantFP::getZero(Op0->getType()); 5751 5752 // +normal number * (-)0.0 --> (-)0.0 5753 if (isKnownNeverInfOrNaN(Op0, Q.DL, Q.TLI, 0, Q.AC, Q.CxtI, Q.DT) && 5754 // TODO: Check SignBit from computeKnownFPClass when it's more complete. 5755 SignBitMustBeZero(Op0, Q.DL, Q.TLI)) 5756 return Op1; 5757 } 5758 5759 // sqrt(X) * sqrt(X) --> X, if we can: 5760 // 1. Remove the intermediate rounding (reassociate). 5761 // 2. Ignore non-zero negative numbers because sqrt would produce NAN. 5762 // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0. 5763 Value *X; 5764 if (Op0 == Op1 && match(Op0, m_Sqrt(m_Value(X))) && FMF.allowReassoc() && 5765 FMF.noNaNs() && FMF.noSignedZeros()) 5766 return X; 5767 5768 return nullptr; 5769 } 5770 5771 /// Given the operands for an FMul, see if we can fold the result 5772 static Value * 5773 simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5774 const SimplifyQuery &Q, unsigned MaxRecurse, 5775 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5776 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5777 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5778 if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q)) 5779 return C; 5780 5781 // Now apply simplifications that do not require rounding. 5782 return simplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse, ExBehavior, Rounding); 5783 } 5784 5785 Value *llvm::simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5786 const SimplifyQuery &Q, 5787 fp::ExceptionBehavior ExBehavior, 5788 RoundingMode Rounding) { 5789 return ::simplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5790 Rounding); 5791 } 5792 5793 Value *llvm::simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5794 const SimplifyQuery &Q, 5795 fp::ExceptionBehavior ExBehavior, 5796 RoundingMode Rounding) { 5797 return ::simplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5798 Rounding); 5799 } 5800 5801 Value *llvm::simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5802 const SimplifyQuery &Q, 5803 fp::ExceptionBehavior ExBehavior, 5804 RoundingMode Rounding) { 5805 return ::simplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5806 Rounding); 5807 } 5808 5809 Value *llvm::simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 5810 const SimplifyQuery &Q, 5811 fp::ExceptionBehavior ExBehavior, 5812 RoundingMode Rounding) { 5813 return ::simplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5814 Rounding); 5815 } 5816 5817 static Value * 5818 simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5819 const SimplifyQuery &Q, unsigned, 5820 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5821 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5822 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5823 if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q)) 5824 return C; 5825 5826 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5827 return C; 5828 5829 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5830 return nullptr; 5831 5832 // X / 1.0 -> X 5833 if (match(Op1, m_FPOne())) 5834 return Op0; 5835 5836 // 0 / X -> 0 5837 // Requires that NaNs are off (X could be zero) and signed zeroes are 5838 // ignored (X could be positive or negative, so the output sign is unknown). 5839 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) 5840 return ConstantFP::getZero(Op0->getType()); 5841 5842 if (FMF.noNaNs()) { 5843 // X / X -> 1.0 is legal when NaNs are ignored. 5844 // We can ignore infinities because INF/INF is NaN. 5845 if (Op0 == Op1) 5846 return ConstantFP::get(Op0->getType(), 1.0); 5847 5848 // (X * Y) / Y --> X if we can reassociate to the above form. 5849 Value *X; 5850 if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1)))) 5851 return X; 5852 5853 // -X / X -> -1.0 and 5854 // X / -X -> -1.0 are legal when NaNs are ignored. 5855 // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored. 5856 if (match(Op0, m_FNegNSZ(m_Specific(Op1))) || 5857 match(Op1, m_FNegNSZ(m_Specific(Op0)))) 5858 return ConstantFP::get(Op0->getType(), -1.0); 5859 5860 // nnan ninf X / [-]0.0 -> poison 5861 if (FMF.noInfs() && match(Op1, m_AnyZeroFP())) 5862 return PoisonValue::get(Op1->getType()); 5863 } 5864 5865 return nullptr; 5866 } 5867 5868 Value *llvm::simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5869 const SimplifyQuery &Q, 5870 fp::ExceptionBehavior ExBehavior, 5871 RoundingMode Rounding) { 5872 return ::simplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5873 Rounding); 5874 } 5875 5876 static Value * 5877 simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5878 const SimplifyQuery &Q, unsigned, 5879 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5880 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5881 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5882 if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q)) 5883 return C; 5884 5885 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5886 return C; 5887 5888 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5889 return nullptr; 5890 5891 // Unlike fdiv, the result of frem always matches the sign of the dividend. 5892 // The constant match may include undef elements in a vector, so return a full 5893 // zero constant as the result. 5894 if (FMF.noNaNs()) { 5895 // +0 % X -> 0 5896 if (match(Op0, m_PosZeroFP())) 5897 return ConstantFP::getZero(Op0->getType()); 5898 // -0 % X -> -0 5899 if (match(Op0, m_NegZeroFP())) 5900 return ConstantFP::getNegativeZero(Op0->getType()); 5901 } 5902 5903 return nullptr; 5904 } 5905 5906 Value *llvm::simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5907 const SimplifyQuery &Q, 5908 fp::ExceptionBehavior ExBehavior, 5909 RoundingMode Rounding) { 5910 return ::simplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5911 Rounding); 5912 } 5913 5914 //=== Helper functions for higher up the class hierarchy. 5915 5916 /// Given the operand for a UnaryOperator, see if we can fold the result. 5917 /// If not, this returns null. 5918 static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q, 5919 unsigned MaxRecurse) { 5920 switch (Opcode) { 5921 case Instruction::FNeg: 5922 return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse); 5923 default: 5924 llvm_unreachable("Unexpected opcode"); 5925 } 5926 } 5927 5928 /// Given the operand for a UnaryOperator, see if we can fold the result. 5929 /// If not, this returns null. 5930 /// Try to use FastMathFlags when folding the result. 5931 static Value *simplifyFPUnOp(unsigned Opcode, Value *Op, 5932 const FastMathFlags &FMF, const SimplifyQuery &Q, 5933 unsigned MaxRecurse) { 5934 switch (Opcode) { 5935 case Instruction::FNeg: 5936 return simplifyFNegInst(Op, FMF, Q, MaxRecurse); 5937 default: 5938 return simplifyUnOp(Opcode, Op, Q, MaxRecurse); 5939 } 5940 } 5941 5942 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) { 5943 return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit); 5944 } 5945 5946 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 5947 const SimplifyQuery &Q) { 5948 return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit); 5949 } 5950 5951 /// Given operands for a BinaryOperator, see if we can fold the result. 5952 /// If not, this returns null. 5953 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5954 const SimplifyQuery &Q, unsigned MaxRecurse) { 5955 switch (Opcode) { 5956 case Instruction::Add: 5957 return simplifyAddInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5958 MaxRecurse); 5959 case Instruction::Sub: 5960 return simplifySubInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5961 MaxRecurse); 5962 case Instruction::Mul: 5963 return simplifyMulInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5964 MaxRecurse); 5965 case Instruction::SDiv: 5966 return simplifySDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5967 case Instruction::UDiv: 5968 return simplifyUDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5969 case Instruction::SRem: 5970 return simplifySRemInst(LHS, RHS, Q, MaxRecurse); 5971 case Instruction::URem: 5972 return simplifyURemInst(LHS, RHS, Q, MaxRecurse); 5973 case Instruction::Shl: 5974 return simplifyShlInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5975 MaxRecurse); 5976 case Instruction::LShr: 5977 return simplifyLShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5978 case Instruction::AShr: 5979 return simplifyAShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5980 case Instruction::And: 5981 return simplifyAndInst(LHS, RHS, Q, MaxRecurse); 5982 case Instruction::Or: 5983 return simplifyOrInst(LHS, RHS, Q, MaxRecurse); 5984 case Instruction::Xor: 5985 return simplifyXorInst(LHS, RHS, Q, MaxRecurse); 5986 case Instruction::FAdd: 5987 return simplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5988 case Instruction::FSub: 5989 return simplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5990 case Instruction::FMul: 5991 return simplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5992 case Instruction::FDiv: 5993 return simplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5994 case Instruction::FRem: 5995 return simplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5996 default: 5997 llvm_unreachable("Unexpected opcode"); 5998 } 5999 } 6000 6001 /// Given operands for a BinaryOperator, see if we can fold the result. 6002 /// If not, this returns null. 6003 /// Try to use FastMathFlags when folding the result. 6004 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6005 const FastMathFlags &FMF, const SimplifyQuery &Q, 6006 unsigned MaxRecurse) { 6007 switch (Opcode) { 6008 case Instruction::FAdd: 6009 return simplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse); 6010 case Instruction::FSub: 6011 return simplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse); 6012 case Instruction::FMul: 6013 return simplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse); 6014 case Instruction::FDiv: 6015 return simplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse); 6016 default: 6017 return simplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse); 6018 } 6019 } 6020 6021 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6022 const SimplifyQuery &Q) { 6023 return ::simplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit); 6024 } 6025 6026 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6027 FastMathFlags FMF, const SimplifyQuery &Q) { 6028 return ::simplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit); 6029 } 6030 6031 /// Given operands for a CmpInst, see if we can fold the result. 6032 static Value *simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 6033 const SimplifyQuery &Q, unsigned MaxRecurse) { 6034 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 6035 return simplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 6036 return simplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6037 } 6038 6039 Value *llvm::simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 6040 const SimplifyQuery &Q) { 6041 return ::simplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 6042 } 6043 6044 static bool isIdempotent(Intrinsic::ID ID) { 6045 switch (ID) { 6046 default: 6047 return false; 6048 6049 // Unary idempotent: f(f(x)) = f(x) 6050 case Intrinsic::fabs: 6051 case Intrinsic::floor: 6052 case Intrinsic::ceil: 6053 case Intrinsic::trunc: 6054 case Intrinsic::rint: 6055 case Intrinsic::nearbyint: 6056 case Intrinsic::round: 6057 case Intrinsic::roundeven: 6058 case Intrinsic::canonicalize: 6059 case Intrinsic::arithmetic_fence: 6060 return true; 6061 } 6062 } 6063 6064 /// Return true if the intrinsic rounds a floating-point value to an integral 6065 /// floating-point value (not an integer type). 6066 static bool removesFPFraction(Intrinsic::ID ID) { 6067 switch (ID) { 6068 default: 6069 return false; 6070 6071 case Intrinsic::floor: 6072 case Intrinsic::ceil: 6073 case Intrinsic::trunc: 6074 case Intrinsic::rint: 6075 case Intrinsic::nearbyint: 6076 case Intrinsic::round: 6077 case Intrinsic::roundeven: 6078 return true; 6079 } 6080 } 6081 6082 static Value *simplifyRelativeLoad(Constant *Ptr, Constant *Offset, 6083 const DataLayout &DL) { 6084 GlobalValue *PtrSym; 6085 APInt PtrOffset; 6086 if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL)) 6087 return nullptr; 6088 6089 Type *Int32Ty = Type::getInt32Ty(Ptr->getContext()); 6090 6091 auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset); 6092 if (!OffsetConstInt || OffsetConstInt->getBitWidth() > 64) 6093 return nullptr; 6094 6095 APInt OffsetInt = OffsetConstInt->getValue().sextOrTrunc( 6096 DL.getIndexTypeSizeInBits(Ptr->getType())); 6097 if (OffsetInt.srem(4) != 0) 6098 return nullptr; 6099 6100 Constant *Loaded = ConstantFoldLoadFromConstPtr(Ptr, Int32Ty, OffsetInt, DL); 6101 if (!Loaded) 6102 return nullptr; 6103 6104 auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded); 6105 if (!LoadedCE) 6106 return nullptr; 6107 6108 if (LoadedCE->getOpcode() == Instruction::Trunc) { 6109 LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 6110 if (!LoadedCE) 6111 return nullptr; 6112 } 6113 6114 if (LoadedCE->getOpcode() != Instruction::Sub) 6115 return nullptr; 6116 6117 auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 6118 if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt) 6119 return nullptr; 6120 auto *LoadedLHSPtr = LoadedLHS->getOperand(0); 6121 6122 Constant *LoadedRHS = LoadedCE->getOperand(1); 6123 GlobalValue *LoadedRHSSym; 6124 APInt LoadedRHSOffset; 6125 if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset, 6126 DL) || 6127 PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset) 6128 return nullptr; 6129 6130 return LoadedLHSPtr; 6131 } 6132 6133 // TODO: Need to pass in FastMathFlags 6134 static Value *simplifyLdexp(Value *Op0, Value *Op1, const SimplifyQuery &Q, 6135 bool IsStrict) { 6136 // ldexp(poison, x) -> poison 6137 // ldexp(x, poison) -> poison 6138 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 6139 return Op0; 6140 6141 // ldexp(undef, x) -> nan 6142 if (Q.isUndefValue(Op0)) 6143 return ConstantFP::getNaN(Op0->getType()); 6144 6145 if (!IsStrict) { 6146 // TODO: Could insert a canonicalize for strict 6147 6148 // ldexp(x, undef) -> x 6149 if (Q.isUndefValue(Op1)) 6150 return Op0; 6151 } 6152 6153 const APFloat *C = nullptr; 6154 match(Op0, PatternMatch::m_APFloat(C)); 6155 6156 // These cases should be safe, even with strictfp. 6157 // ldexp(0.0, x) -> 0.0 6158 // ldexp(-0.0, x) -> -0.0 6159 // ldexp(inf, x) -> inf 6160 // ldexp(-inf, x) -> -inf 6161 if (C && (C->isZero() || C->isInfinity())) 6162 return Op0; 6163 6164 // These are canonicalization dropping, could do it if we knew how we could 6165 // ignore denormal flushes and target handling of nan payload bits. 6166 if (IsStrict) 6167 return nullptr; 6168 6169 // TODO: Could quiet this with strictfp if the exception mode isn't strict. 6170 if (C && C->isNaN()) 6171 return ConstantFP::get(Op0->getType(), C->makeQuiet()); 6172 6173 // ldexp(x, 0) -> x 6174 6175 // TODO: Could fold this if we know the exception mode isn't 6176 // strict, we know the denormal mode and other target modes. 6177 if (match(Op1, PatternMatch::m_ZeroInt())) 6178 return Op0; 6179 6180 return nullptr; 6181 } 6182 6183 static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0, 6184 const SimplifyQuery &Q, 6185 const CallBase *Call) { 6186 // Idempotent functions return the same result when called repeatedly. 6187 Intrinsic::ID IID = F->getIntrinsicID(); 6188 if (isIdempotent(IID)) 6189 if (auto *II = dyn_cast<IntrinsicInst>(Op0)) 6190 if (II->getIntrinsicID() == IID) 6191 return II; 6192 6193 if (removesFPFraction(IID)) { 6194 // Converting from int or calling a rounding function always results in a 6195 // finite integral number or infinity. For those inputs, rounding functions 6196 // always return the same value, so the (2nd) rounding is eliminated. Ex: 6197 // floor (sitofp x) -> sitofp x 6198 // round (ceil x) -> ceil x 6199 auto *II = dyn_cast<IntrinsicInst>(Op0); 6200 if ((II && removesFPFraction(II->getIntrinsicID())) || 6201 match(Op0, m_SIToFP(m_Value())) || match(Op0, m_UIToFP(m_Value()))) 6202 return Op0; 6203 } 6204 6205 Value *X; 6206 switch (IID) { 6207 case Intrinsic::fabs: 6208 if (SignBitMustBeZero(Op0, Q.DL, Q.TLI)) 6209 return Op0; 6210 break; 6211 case Intrinsic::bswap: 6212 // bswap(bswap(x)) -> x 6213 if (match(Op0, m_BSwap(m_Value(X)))) 6214 return X; 6215 break; 6216 case Intrinsic::bitreverse: 6217 // bitreverse(bitreverse(x)) -> x 6218 if (match(Op0, m_BitReverse(m_Value(X)))) 6219 return X; 6220 break; 6221 case Intrinsic::ctpop: { 6222 // ctpop(X) -> 1 iff X is non-zero power of 2. 6223 if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ false, 0, Q.AC, Q.CxtI, 6224 Q.DT)) 6225 return ConstantInt::get(Op0->getType(), 1); 6226 // If everything but the lowest bit is zero, that bit is the pop-count. Ex: 6227 // ctpop(and X, 1) --> and X, 1 6228 unsigned BitWidth = Op0->getType()->getScalarSizeInBits(); 6229 if (MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, BitWidth - 1), 6230 Q)) 6231 return Op0; 6232 break; 6233 } 6234 case Intrinsic::exp: 6235 // exp(log(x)) -> x 6236 if (Call->hasAllowReassoc() && 6237 match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X)))) 6238 return X; 6239 break; 6240 case Intrinsic::exp2: 6241 // exp2(log2(x)) -> x 6242 if (Call->hasAllowReassoc() && 6243 match(Op0, m_Intrinsic<Intrinsic::log2>(m_Value(X)))) 6244 return X; 6245 break; 6246 case Intrinsic::exp10: 6247 // exp10(log10(x)) -> x 6248 if (Call->hasAllowReassoc() && 6249 match(Op0, m_Intrinsic<Intrinsic::log10>(m_Value(X)))) 6250 return X; 6251 break; 6252 case Intrinsic::log: 6253 // log(exp(x)) -> x 6254 if (Call->hasAllowReassoc() && 6255 match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X)))) 6256 return X; 6257 break; 6258 case Intrinsic::log2: 6259 // log2(exp2(x)) -> x 6260 if (Call->hasAllowReassoc() && 6261 (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) || 6262 match(Op0, 6263 m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0), m_Value(X))))) 6264 return X; 6265 break; 6266 case Intrinsic::log10: 6267 // log10(pow(10.0, x)) -> x 6268 // log10(exp10(x)) -> x 6269 if (Call->hasAllowReassoc() && 6270 (match(Op0, m_Intrinsic<Intrinsic::exp10>(m_Value(X))) || 6271 match(Op0, 6272 m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), m_Value(X))))) 6273 return X; 6274 break; 6275 case Intrinsic::experimental_vector_reverse: 6276 // experimental.vector.reverse(experimental.vector.reverse(x)) -> x 6277 if (match(Op0, m_VecReverse(m_Value(X)))) 6278 return X; 6279 // experimental.vector.reverse(splat(X)) -> splat(X) 6280 if (isSplatValue(Op0)) 6281 return Op0; 6282 break; 6283 case Intrinsic::frexp: { 6284 // Frexp is idempotent with the added complication of the struct return. 6285 if (match(Op0, m_ExtractValue<0>(m_Value(X)))) { 6286 if (match(X, m_Intrinsic<Intrinsic::frexp>(m_Value()))) 6287 return X; 6288 } 6289 6290 break; 6291 } 6292 default: 6293 break; 6294 } 6295 6296 return nullptr; 6297 } 6298 6299 /// Given a min/max intrinsic, see if it can be removed based on having an 6300 /// operand that is another min/max intrinsic with shared operand(s). The caller 6301 /// is expected to swap the operand arguments to handle commutation. 6302 static Value *foldMinMaxSharedOp(Intrinsic::ID IID, Value *Op0, Value *Op1) { 6303 Value *X, *Y; 6304 if (!match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y)))) 6305 return nullptr; 6306 6307 auto *MM0 = dyn_cast<IntrinsicInst>(Op0); 6308 if (!MM0) 6309 return nullptr; 6310 Intrinsic::ID IID0 = MM0->getIntrinsicID(); 6311 6312 if (Op1 == X || Op1 == Y || 6313 match(Op1, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) { 6314 // max (max X, Y), X --> max X, Y 6315 if (IID0 == IID) 6316 return MM0; 6317 // max (min X, Y), X --> X 6318 if (IID0 == getInverseMinMaxIntrinsic(IID)) 6319 return Op1; 6320 } 6321 return nullptr; 6322 } 6323 6324 /// Given a min/max intrinsic, see if it can be removed based on having an 6325 /// operand that is another min/max intrinsic with shared operand(s). The caller 6326 /// is expected to swap the operand arguments to handle commutation. 6327 static Value *foldMinimumMaximumSharedOp(Intrinsic::ID IID, Value *Op0, 6328 Value *Op1) { 6329 assert((IID == Intrinsic::maxnum || IID == Intrinsic::minnum || 6330 IID == Intrinsic::maximum || IID == Intrinsic::minimum) && 6331 "Unsupported intrinsic"); 6332 6333 auto *M0 = dyn_cast<IntrinsicInst>(Op0); 6334 // If Op0 is not the same intrinsic as IID, do not process. 6335 // This is a difference with integer min/max handling. We do not process the 6336 // case like max(min(X,Y),min(X,Y)) => min(X,Y). But it can be handled by GVN. 6337 if (!M0 || M0->getIntrinsicID() != IID) 6338 return nullptr; 6339 Value *X0 = M0->getOperand(0); 6340 Value *Y0 = M0->getOperand(1); 6341 // Simple case, m(m(X,Y), X) => m(X, Y) 6342 // m(m(X,Y), Y) => m(X, Y) 6343 // For minimum/maximum, X is NaN => m(NaN, Y) == NaN and m(NaN, NaN) == NaN. 6344 // For minimum/maximum, Y is NaN => m(X, NaN) == NaN and m(NaN, NaN) == NaN. 6345 // For minnum/maxnum, X is NaN => m(NaN, Y) == Y and m(Y, Y) == Y. 6346 // For minnum/maxnum, Y is NaN => m(X, NaN) == X and m(X, NaN) == X. 6347 if (X0 == Op1 || Y0 == Op1) 6348 return M0; 6349 6350 auto *M1 = dyn_cast<IntrinsicInst>(Op1); 6351 if (!M1) 6352 return nullptr; 6353 Value *X1 = M1->getOperand(0); 6354 Value *Y1 = M1->getOperand(1); 6355 Intrinsic::ID IID1 = M1->getIntrinsicID(); 6356 // we have a case m(m(X,Y),m'(X,Y)) taking into account m' is commutative. 6357 // if m' is m or inversion of m => m(m(X,Y),m'(X,Y)) == m(X,Y). 6358 // For minimum/maximum, X is NaN => m(NaN,Y) == m'(NaN, Y) == NaN. 6359 // For minimum/maximum, Y is NaN => m(X,NaN) == m'(X, NaN) == NaN. 6360 // For minnum/maxnum, X is NaN => m(NaN,Y) == m'(NaN, Y) == Y. 6361 // For minnum/maxnum, Y is NaN => m(X,NaN) == m'(X, NaN) == X. 6362 if ((X0 == X1 && Y0 == Y1) || (X0 == Y1 && Y0 == X1)) 6363 if (IID1 == IID || getInverseMinMaxIntrinsic(IID1) == IID) 6364 return M0; 6365 6366 return nullptr; 6367 } 6368 6369 static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1, 6370 const SimplifyQuery &Q, 6371 const CallBase *Call) { 6372 Intrinsic::ID IID = F->getIntrinsicID(); 6373 Type *ReturnType = F->getReturnType(); 6374 unsigned BitWidth = ReturnType->getScalarSizeInBits(); 6375 switch (IID) { 6376 case Intrinsic::abs: 6377 // abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here. 6378 // It is always ok to pick the earlier abs. We'll just lose nsw if its only 6379 // on the outer abs. 6380 if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(), m_Value()))) 6381 return Op0; 6382 break; 6383 6384 case Intrinsic::cttz: { 6385 Value *X; 6386 if (match(Op0, m_Shl(m_One(), m_Value(X)))) 6387 return X; 6388 break; 6389 } 6390 case Intrinsic::ctlz: { 6391 Value *X; 6392 if (match(Op0, m_LShr(m_Negative(), m_Value(X)))) 6393 return X; 6394 if (match(Op0, m_AShr(m_Negative(), m_Value()))) 6395 return Constant::getNullValue(ReturnType); 6396 break; 6397 } 6398 case Intrinsic::ptrmask: { 6399 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 6400 return PoisonValue::get(Op0->getType()); 6401 6402 // NOTE: We can't apply this simplifications based on the value of Op1 6403 // because we need to preserve provenance. 6404 if (Q.isUndefValue(Op0) || match(Op0, m_Zero())) 6405 return Constant::getNullValue(Op0->getType()); 6406 6407 assert(Op1->getType()->getScalarSizeInBits() == 6408 Q.DL.getIndexTypeSizeInBits(Op0->getType()) && 6409 "Invalid mask width"); 6410 // If index-width (mask size) is less than pointer-size then mask is 6411 // 1-extended. 6412 if (match(Op1, m_PtrToInt(m_Specific(Op0)))) 6413 return Op0; 6414 6415 // NOTE: We may have attributes associated with the return value of the 6416 // llvm.ptrmask intrinsic that will be lost when we just return the 6417 // operand. We should try to preserve them. 6418 if (match(Op1, m_AllOnes()) || Q.isUndefValue(Op1)) 6419 return Op0; 6420 6421 Constant *C; 6422 if (match(Op1, m_ImmConstant(C))) { 6423 KnownBits PtrKnown = computeKnownBits(Op0, /*Depth=*/0, Q); 6424 // See if we only masking off bits we know are already zero due to 6425 // alignment. 6426 APInt IrrelevantPtrBits = 6427 PtrKnown.Zero.zextOrTrunc(C->getType()->getScalarSizeInBits()); 6428 C = ConstantFoldBinaryOpOperands( 6429 Instruction::Or, C, ConstantInt::get(C->getType(), IrrelevantPtrBits), 6430 Q.DL); 6431 if (C != nullptr && C->isAllOnesValue()) 6432 return Op0; 6433 } 6434 break; 6435 } 6436 case Intrinsic::smax: 6437 case Intrinsic::smin: 6438 case Intrinsic::umax: 6439 case Intrinsic::umin: { 6440 // If the arguments are the same, this is a no-op. 6441 if (Op0 == Op1) 6442 return Op0; 6443 6444 // Canonicalize immediate constant operand as Op1. 6445 if (match(Op0, m_ImmConstant())) 6446 std::swap(Op0, Op1); 6447 6448 // Assume undef is the limit value. 6449 if (Q.isUndefValue(Op1)) 6450 return ConstantInt::get( 6451 ReturnType, MinMaxIntrinsic::getSaturationPoint(IID, BitWidth)); 6452 6453 const APInt *C; 6454 if (match(Op1, m_APIntAllowUndef(C))) { 6455 // Clamp to limit value. For example: 6456 // umax(i8 %x, i8 255) --> 255 6457 if (*C == MinMaxIntrinsic::getSaturationPoint(IID, BitWidth)) 6458 return ConstantInt::get(ReturnType, *C); 6459 6460 // If the constant op is the opposite of the limit value, the other must 6461 // be larger/smaller or equal. For example: 6462 // umin(i8 %x, i8 255) --> %x 6463 if (*C == MinMaxIntrinsic::getSaturationPoint( 6464 getInverseMinMaxIntrinsic(IID), BitWidth)) 6465 return Op0; 6466 6467 // Remove nested call if constant operands allow it. Example: 6468 // max (max X, 7), 5 -> max X, 7 6469 auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0); 6470 if (MinMax0 && MinMax0->getIntrinsicID() == IID) { 6471 // TODO: loosen undef/splat restrictions for vector constants. 6472 Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1); 6473 const APInt *InnerC; 6474 if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) && 6475 ICmpInst::compare(*InnerC, *C, 6476 ICmpInst::getNonStrictPredicate( 6477 MinMaxIntrinsic::getPredicate(IID)))) 6478 return Op0; 6479 } 6480 } 6481 6482 if (Value *V = foldMinMaxSharedOp(IID, Op0, Op1)) 6483 return V; 6484 if (Value *V = foldMinMaxSharedOp(IID, Op1, Op0)) 6485 return V; 6486 6487 ICmpInst::Predicate Pred = 6488 ICmpInst::getNonStrictPredicate(MinMaxIntrinsic::getPredicate(IID)); 6489 if (isICmpTrue(Pred, Op0, Op1, Q.getWithoutUndef(), RecursionLimit)) 6490 return Op0; 6491 if (isICmpTrue(Pred, Op1, Op0, Q.getWithoutUndef(), RecursionLimit)) 6492 return Op1; 6493 6494 break; 6495 } 6496 case Intrinsic::usub_with_overflow: 6497 case Intrinsic::ssub_with_overflow: 6498 // X - X -> { 0, false } 6499 // X - undef -> { 0, false } 6500 // undef - X -> { 0, false } 6501 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6502 return Constant::getNullValue(ReturnType); 6503 break; 6504 case Intrinsic::uadd_with_overflow: 6505 case Intrinsic::sadd_with_overflow: 6506 // X + undef -> { -1, false } 6507 // undef + x -> { -1, false } 6508 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) { 6509 return ConstantStruct::get( 6510 cast<StructType>(ReturnType), 6511 {Constant::getAllOnesValue(ReturnType->getStructElementType(0)), 6512 Constant::getNullValue(ReturnType->getStructElementType(1))}); 6513 } 6514 break; 6515 case Intrinsic::umul_with_overflow: 6516 case Intrinsic::smul_with_overflow: 6517 // 0 * X -> { 0, false } 6518 // X * 0 -> { 0, false } 6519 if (match(Op0, m_Zero()) || match(Op1, m_Zero())) 6520 return Constant::getNullValue(ReturnType); 6521 // undef * X -> { 0, false } 6522 // X * undef -> { 0, false } 6523 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6524 return Constant::getNullValue(ReturnType); 6525 break; 6526 case Intrinsic::uadd_sat: 6527 // sat(MAX + X) -> MAX 6528 // sat(X + MAX) -> MAX 6529 if (match(Op0, m_AllOnes()) || match(Op1, m_AllOnes())) 6530 return Constant::getAllOnesValue(ReturnType); 6531 [[fallthrough]]; 6532 case Intrinsic::sadd_sat: 6533 // sat(X + undef) -> -1 6534 // sat(undef + X) -> -1 6535 // For unsigned: Assume undef is MAX, thus we saturate to MAX (-1). 6536 // For signed: Assume undef is ~X, in which case X + ~X = -1. 6537 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6538 return Constant::getAllOnesValue(ReturnType); 6539 6540 // X + 0 -> X 6541 if (match(Op1, m_Zero())) 6542 return Op0; 6543 // 0 + X -> X 6544 if (match(Op0, m_Zero())) 6545 return Op1; 6546 break; 6547 case Intrinsic::usub_sat: 6548 // sat(0 - X) -> 0, sat(X - MAX) -> 0 6549 if (match(Op0, m_Zero()) || match(Op1, m_AllOnes())) 6550 return Constant::getNullValue(ReturnType); 6551 [[fallthrough]]; 6552 case Intrinsic::ssub_sat: 6553 // X - X -> 0, X - undef -> 0, undef - X -> 0 6554 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6555 return Constant::getNullValue(ReturnType); 6556 // X - 0 -> X 6557 if (match(Op1, m_Zero())) 6558 return Op0; 6559 break; 6560 case Intrinsic::load_relative: 6561 if (auto *C0 = dyn_cast<Constant>(Op0)) 6562 if (auto *C1 = dyn_cast<Constant>(Op1)) 6563 return simplifyRelativeLoad(C0, C1, Q.DL); 6564 break; 6565 case Intrinsic::powi: 6566 if (auto *Power = dyn_cast<ConstantInt>(Op1)) { 6567 // powi(x, 0) -> 1.0 6568 if (Power->isZero()) 6569 return ConstantFP::get(Op0->getType(), 1.0); 6570 // powi(x, 1) -> x 6571 if (Power->isOne()) 6572 return Op0; 6573 } 6574 break; 6575 case Intrinsic::ldexp: 6576 return simplifyLdexp(Op0, Op1, Q, false); 6577 case Intrinsic::copysign: 6578 // copysign X, X --> X 6579 if (Op0 == Op1) 6580 return Op0; 6581 // copysign -X, X --> X 6582 // copysign X, -X --> -X 6583 if (match(Op0, m_FNeg(m_Specific(Op1))) || 6584 match(Op1, m_FNeg(m_Specific(Op0)))) 6585 return Op1; 6586 break; 6587 case Intrinsic::is_fpclass: { 6588 if (isa<PoisonValue>(Op0)) 6589 return PoisonValue::get(ReturnType); 6590 6591 uint64_t Mask = cast<ConstantInt>(Op1)->getZExtValue(); 6592 // If all tests are made, it doesn't matter what the value is. 6593 if ((Mask & fcAllFlags) == fcAllFlags) 6594 return ConstantInt::get(ReturnType, true); 6595 if ((Mask & fcAllFlags) == 0) 6596 return ConstantInt::get(ReturnType, false); 6597 if (Q.isUndefValue(Op0)) 6598 return UndefValue::get(ReturnType); 6599 break; 6600 } 6601 case Intrinsic::maxnum: 6602 case Intrinsic::minnum: 6603 case Intrinsic::maximum: 6604 case Intrinsic::minimum: { 6605 // If the arguments are the same, this is a no-op. 6606 if (Op0 == Op1) 6607 return Op0; 6608 6609 // Canonicalize constant operand as Op1. 6610 if (isa<Constant>(Op0)) 6611 std::swap(Op0, Op1); 6612 6613 // If an argument is undef, return the other argument. 6614 if (Q.isUndefValue(Op1)) 6615 return Op0; 6616 6617 bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum; 6618 bool IsMin = IID == Intrinsic::minimum || IID == Intrinsic::minnum; 6619 6620 // minnum(X, nan) -> X 6621 // maxnum(X, nan) -> X 6622 // minimum(X, nan) -> nan 6623 // maximum(X, nan) -> nan 6624 if (match(Op1, m_NaN())) 6625 return PropagateNaN ? propagateNaN(cast<Constant>(Op1)) : Op0; 6626 6627 // In the following folds, inf can be replaced with the largest finite 6628 // float, if the ninf flag is set. 6629 const APFloat *C; 6630 if (match(Op1, m_APFloat(C)) && 6631 (C->isInfinity() || (Call->hasNoInfs() && C->isLargest()))) { 6632 // minnum(X, -inf) -> -inf 6633 // maxnum(X, +inf) -> +inf 6634 // minimum(X, -inf) -> -inf if nnan 6635 // maximum(X, +inf) -> +inf if nnan 6636 if (C->isNegative() == IsMin && (!PropagateNaN || Call->hasNoNaNs())) 6637 return ConstantFP::get(ReturnType, *C); 6638 6639 // minnum(X, +inf) -> X if nnan 6640 // maxnum(X, -inf) -> X if nnan 6641 // minimum(X, +inf) -> X 6642 // maximum(X, -inf) -> X 6643 if (C->isNegative() != IsMin && (PropagateNaN || Call->hasNoNaNs())) 6644 return Op0; 6645 } 6646 6647 // Min/max of the same operation with common operand: 6648 // m(m(X, Y)), X --> m(X, Y) (4 commuted variants) 6649 if (Value *V = foldMinimumMaximumSharedOp(IID, Op0, Op1)) 6650 return V; 6651 if (Value *V = foldMinimumMaximumSharedOp(IID, Op1, Op0)) 6652 return V; 6653 6654 break; 6655 } 6656 case Intrinsic::vector_extract: { 6657 Type *ReturnType = F->getReturnType(); 6658 6659 // (extract_vector (insert_vector _, X, 0), 0) -> X 6660 unsigned IdxN = cast<ConstantInt>(Op1)->getZExtValue(); 6661 Value *X = nullptr; 6662 if (match(Op0, m_Intrinsic<Intrinsic::vector_insert>(m_Value(), m_Value(X), 6663 m_Zero())) && 6664 IdxN == 0 && X->getType() == ReturnType) 6665 return X; 6666 6667 break; 6668 } 6669 default: 6670 break; 6671 } 6672 6673 return nullptr; 6674 } 6675 6676 static Value *simplifyIntrinsic(CallBase *Call, Value *Callee, 6677 ArrayRef<Value *> Args, 6678 const SimplifyQuery &Q) { 6679 // Operand bundles should not be in Args. 6680 assert(Call->arg_size() == Args.size()); 6681 unsigned NumOperands = Args.size(); 6682 Function *F = cast<Function>(Callee); 6683 Intrinsic::ID IID = F->getIntrinsicID(); 6684 6685 // Most of the intrinsics with no operands have some kind of side effect. 6686 // Don't simplify. 6687 if (!NumOperands) { 6688 switch (IID) { 6689 case Intrinsic::vscale: { 6690 Type *RetTy = F->getReturnType(); 6691 ConstantRange CR = getVScaleRange(Call->getFunction(), 64); 6692 if (const APInt *C = CR.getSingleElement()) 6693 return ConstantInt::get(RetTy, C->getZExtValue()); 6694 return nullptr; 6695 } 6696 default: 6697 return nullptr; 6698 } 6699 } 6700 6701 if (NumOperands == 1) 6702 return simplifyUnaryIntrinsic(F, Args[0], Q, Call); 6703 6704 if (NumOperands == 2) 6705 return simplifyBinaryIntrinsic(F, Args[0], Args[1], Q, Call); 6706 6707 // Handle intrinsics with 3 or more arguments. 6708 switch (IID) { 6709 case Intrinsic::masked_load: 6710 case Intrinsic::masked_gather: { 6711 Value *MaskArg = Args[2]; 6712 Value *PassthruArg = Args[3]; 6713 // If the mask is all zeros or undef, the "passthru" argument is the result. 6714 if (maskIsAllZeroOrUndef(MaskArg)) 6715 return PassthruArg; 6716 return nullptr; 6717 } 6718 case Intrinsic::fshl: 6719 case Intrinsic::fshr: { 6720 Value *Op0 = Args[0], *Op1 = Args[1], *ShAmtArg = Args[2]; 6721 6722 // If both operands are undef, the result is undef. 6723 if (Q.isUndefValue(Op0) && Q.isUndefValue(Op1)) 6724 return UndefValue::get(F->getReturnType()); 6725 6726 // If shift amount is undef, assume it is zero. 6727 if (Q.isUndefValue(ShAmtArg)) 6728 return Args[IID == Intrinsic::fshl ? 0 : 1]; 6729 6730 const APInt *ShAmtC; 6731 if (match(ShAmtArg, m_APInt(ShAmtC))) { 6732 // If there's effectively no shift, return the 1st arg or 2nd arg. 6733 APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth()); 6734 if (ShAmtC->urem(BitWidth).isZero()) 6735 return Args[IID == Intrinsic::fshl ? 0 : 1]; 6736 } 6737 6738 // Rotating zero by anything is zero. 6739 if (match(Op0, m_Zero()) && match(Op1, m_Zero())) 6740 return ConstantInt::getNullValue(F->getReturnType()); 6741 6742 // Rotating -1 by anything is -1. 6743 if (match(Op0, m_AllOnes()) && match(Op1, m_AllOnes())) 6744 return ConstantInt::getAllOnesValue(F->getReturnType()); 6745 6746 return nullptr; 6747 } 6748 case Intrinsic::experimental_constrained_fma: { 6749 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6750 if (Value *V = simplifyFPOp(Args, {}, Q, *FPI->getExceptionBehavior(), 6751 *FPI->getRoundingMode())) 6752 return V; 6753 return nullptr; 6754 } 6755 case Intrinsic::fma: 6756 case Intrinsic::fmuladd: { 6757 if (Value *V = simplifyFPOp(Args, {}, Q, fp::ebIgnore, 6758 RoundingMode::NearestTiesToEven)) 6759 return V; 6760 return nullptr; 6761 } 6762 case Intrinsic::smul_fix: 6763 case Intrinsic::smul_fix_sat: { 6764 Value *Op0 = Args[0]; 6765 Value *Op1 = Args[1]; 6766 Value *Op2 = Args[2]; 6767 Type *ReturnType = F->getReturnType(); 6768 6769 // Canonicalize constant operand as Op1 (ConstantFolding handles the case 6770 // when both Op0 and Op1 are constant so we do not care about that special 6771 // case here). 6772 if (isa<Constant>(Op0)) 6773 std::swap(Op0, Op1); 6774 6775 // X * 0 -> 0 6776 if (match(Op1, m_Zero())) 6777 return Constant::getNullValue(ReturnType); 6778 6779 // X * undef -> 0 6780 if (Q.isUndefValue(Op1)) 6781 return Constant::getNullValue(ReturnType); 6782 6783 // X * (1 << Scale) -> X 6784 APInt ScaledOne = 6785 APInt::getOneBitSet(ReturnType->getScalarSizeInBits(), 6786 cast<ConstantInt>(Op2)->getZExtValue()); 6787 if (ScaledOne.isNonNegative() && match(Op1, m_SpecificInt(ScaledOne))) 6788 return Op0; 6789 6790 return nullptr; 6791 } 6792 case Intrinsic::vector_insert: { 6793 Value *Vec = Args[0]; 6794 Value *SubVec = Args[1]; 6795 Value *Idx = Args[2]; 6796 Type *ReturnType = F->getReturnType(); 6797 6798 // (insert_vector Y, (extract_vector X, 0), 0) -> X 6799 // where: Y is X, or Y is undef 6800 unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue(); 6801 Value *X = nullptr; 6802 if (match(SubVec, 6803 m_Intrinsic<Intrinsic::vector_extract>(m_Value(X), m_Zero())) && 6804 (Q.isUndefValue(Vec) || Vec == X) && IdxN == 0 && 6805 X->getType() == ReturnType) 6806 return X; 6807 6808 return nullptr; 6809 } 6810 case Intrinsic::experimental_constrained_fadd: { 6811 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6812 return simplifyFAddInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6813 *FPI->getExceptionBehavior(), 6814 *FPI->getRoundingMode()); 6815 } 6816 case Intrinsic::experimental_constrained_fsub: { 6817 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6818 return simplifyFSubInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6819 *FPI->getExceptionBehavior(), 6820 *FPI->getRoundingMode()); 6821 } 6822 case Intrinsic::experimental_constrained_fmul: { 6823 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6824 return simplifyFMulInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6825 *FPI->getExceptionBehavior(), 6826 *FPI->getRoundingMode()); 6827 } 6828 case Intrinsic::experimental_constrained_fdiv: { 6829 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6830 return simplifyFDivInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6831 *FPI->getExceptionBehavior(), 6832 *FPI->getRoundingMode()); 6833 } 6834 case Intrinsic::experimental_constrained_frem: { 6835 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6836 return simplifyFRemInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6837 *FPI->getExceptionBehavior(), 6838 *FPI->getRoundingMode()); 6839 } 6840 case Intrinsic::experimental_constrained_ldexp: 6841 return simplifyLdexp(Args[0], Args[1], Q, true); 6842 default: 6843 return nullptr; 6844 } 6845 } 6846 6847 static Value *tryConstantFoldCall(CallBase *Call, Value *Callee, 6848 ArrayRef<Value *> Args, 6849 const SimplifyQuery &Q) { 6850 auto *F = dyn_cast<Function>(Callee); 6851 if (!F || !canConstantFoldCallTo(Call, F)) 6852 return nullptr; 6853 6854 SmallVector<Constant *, 4> ConstantArgs; 6855 ConstantArgs.reserve(Args.size()); 6856 for (Value *Arg : Args) { 6857 Constant *C = dyn_cast<Constant>(Arg); 6858 if (!C) { 6859 if (isa<MetadataAsValue>(Arg)) 6860 continue; 6861 return nullptr; 6862 } 6863 ConstantArgs.push_back(C); 6864 } 6865 6866 return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI); 6867 } 6868 6869 Value *llvm::simplifyCall(CallBase *Call, Value *Callee, ArrayRef<Value *> Args, 6870 const SimplifyQuery &Q) { 6871 // Args should not contain operand bundle operands. 6872 assert(Call->arg_size() == Args.size()); 6873 6874 // musttail calls can only be simplified if they are also DCEd. 6875 // As we can't guarantee this here, don't simplify them. 6876 if (Call->isMustTailCall()) 6877 return nullptr; 6878 6879 // call undef -> poison 6880 // call null -> poison 6881 if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee)) 6882 return PoisonValue::get(Call->getType()); 6883 6884 if (Value *V = tryConstantFoldCall(Call, Callee, Args, Q)) 6885 return V; 6886 6887 auto *F = dyn_cast<Function>(Callee); 6888 if (F && F->isIntrinsic()) 6889 if (Value *Ret = simplifyIntrinsic(Call, Callee, Args, Q)) 6890 return Ret; 6891 6892 return nullptr; 6893 } 6894 6895 Value *llvm::simplifyConstrainedFPCall(CallBase *Call, const SimplifyQuery &Q) { 6896 assert(isa<ConstrainedFPIntrinsic>(Call)); 6897 SmallVector<Value *, 4> Args(Call->args()); 6898 if (Value *V = tryConstantFoldCall(Call, Call->getCalledOperand(), Args, Q)) 6899 return V; 6900 if (Value *Ret = simplifyIntrinsic(Call, Call->getCalledOperand(), Args, Q)) 6901 return Ret; 6902 return nullptr; 6903 } 6904 6905 /// Given operands for a Freeze, see if we can fold the result. 6906 static Value *simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 6907 // Use a utility function defined in ValueTracking. 6908 if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT)) 6909 return Op0; 6910 // We have room for improvement. 6911 return nullptr; 6912 } 6913 6914 Value *llvm::simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 6915 return ::simplifyFreezeInst(Op0, Q); 6916 } 6917 6918 Value *llvm::simplifyLoadInst(LoadInst *LI, Value *PtrOp, 6919 const SimplifyQuery &Q) { 6920 if (LI->isVolatile()) 6921 return nullptr; 6922 6923 if (auto *PtrOpC = dyn_cast<Constant>(PtrOp)) 6924 return ConstantFoldLoadFromConstPtr(PtrOpC, LI->getType(), Q.DL); 6925 6926 // We can only fold the load if it is from a constant global with definitive 6927 // initializer. Skip expensive logic if this is not the case. 6928 auto *GV = dyn_cast<GlobalVariable>(getUnderlyingObject(PtrOp)); 6929 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) 6930 return nullptr; 6931 6932 // If GlobalVariable's initializer is uniform, then return the constant 6933 // regardless of its offset. 6934 if (Constant *C = 6935 ConstantFoldLoadFromUniformValue(GV->getInitializer(), LI->getType())) 6936 return C; 6937 6938 // Try to convert operand into a constant by stripping offsets while looking 6939 // through invariant.group intrinsics. 6940 APInt Offset(Q.DL.getIndexTypeSizeInBits(PtrOp->getType()), 0); 6941 PtrOp = PtrOp->stripAndAccumulateConstantOffsets( 6942 Q.DL, Offset, /* AllowNonInbounts */ true, 6943 /* AllowInvariantGroup */ true); 6944 if (PtrOp == GV) { 6945 // Index size may have changed due to address space casts. 6946 Offset = Offset.sextOrTrunc(Q.DL.getIndexTypeSizeInBits(PtrOp->getType())); 6947 return ConstantFoldLoadFromConstPtr(GV, LI->getType(), Offset, Q.DL); 6948 } 6949 6950 return nullptr; 6951 } 6952 6953 /// See if we can compute a simplified version of this instruction. 6954 /// If not, this returns null. 6955 6956 static Value *simplifyInstructionWithOperands(Instruction *I, 6957 ArrayRef<Value *> NewOps, 6958 const SimplifyQuery &SQ, 6959 unsigned MaxRecurse) { 6960 assert(I->getFunction() && "instruction should be inserted in a function"); 6961 assert((!SQ.CxtI || SQ.CxtI->getFunction() == I->getFunction()) && 6962 "context instruction should be in the same function"); 6963 6964 const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I); 6965 6966 switch (I->getOpcode()) { 6967 default: 6968 if (llvm::all_of(NewOps, [](Value *V) { return isa<Constant>(V); })) { 6969 SmallVector<Constant *, 8> NewConstOps(NewOps.size()); 6970 transform(NewOps, NewConstOps.begin(), 6971 [](Value *V) { return cast<Constant>(V); }); 6972 return ConstantFoldInstOperands(I, NewConstOps, Q.DL, Q.TLI); 6973 } 6974 return nullptr; 6975 case Instruction::FNeg: 6976 return simplifyFNegInst(NewOps[0], I->getFastMathFlags(), Q, MaxRecurse); 6977 case Instruction::FAdd: 6978 return simplifyFAddInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 6979 MaxRecurse); 6980 case Instruction::Add: 6981 return simplifyAddInst( 6982 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 6983 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 6984 case Instruction::FSub: 6985 return simplifyFSubInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 6986 MaxRecurse); 6987 case Instruction::Sub: 6988 return simplifySubInst( 6989 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 6990 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 6991 case Instruction::FMul: 6992 return simplifyFMulInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 6993 MaxRecurse); 6994 case Instruction::Mul: 6995 return simplifyMulInst( 6996 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 6997 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 6998 case Instruction::SDiv: 6999 return simplifySDivInst(NewOps[0], NewOps[1], 7000 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7001 MaxRecurse); 7002 case Instruction::UDiv: 7003 return simplifyUDivInst(NewOps[0], NewOps[1], 7004 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7005 MaxRecurse); 7006 case Instruction::FDiv: 7007 return simplifyFDivInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7008 MaxRecurse); 7009 case Instruction::SRem: 7010 return simplifySRemInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7011 case Instruction::URem: 7012 return simplifyURemInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7013 case Instruction::FRem: 7014 return simplifyFRemInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7015 MaxRecurse); 7016 case Instruction::Shl: 7017 return simplifyShlInst( 7018 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7019 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7020 case Instruction::LShr: 7021 return simplifyLShrInst(NewOps[0], NewOps[1], 7022 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7023 MaxRecurse); 7024 case Instruction::AShr: 7025 return simplifyAShrInst(NewOps[0], NewOps[1], 7026 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7027 MaxRecurse); 7028 case Instruction::And: 7029 return simplifyAndInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7030 case Instruction::Or: 7031 return simplifyOrInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7032 case Instruction::Xor: 7033 return simplifyXorInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7034 case Instruction::ICmp: 7035 return simplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), NewOps[0], 7036 NewOps[1], Q, MaxRecurse); 7037 case Instruction::FCmp: 7038 return simplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), NewOps[0], 7039 NewOps[1], I->getFastMathFlags(), Q, MaxRecurse); 7040 case Instruction::Select: 7041 return simplifySelectInst(NewOps[0], NewOps[1], NewOps[2], Q, MaxRecurse); 7042 break; 7043 case Instruction::GetElementPtr: { 7044 auto *GEPI = cast<GetElementPtrInst>(I); 7045 return simplifyGEPInst(GEPI->getSourceElementType(), NewOps[0], 7046 ArrayRef(NewOps).slice(1), GEPI->isInBounds(), Q, 7047 MaxRecurse); 7048 } 7049 case Instruction::InsertValue: { 7050 InsertValueInst *IV = cast<InsertValueInst>(I); 7051 return simplifyInsertValueInst(NewOps[0], NewOps[1], IV->getIndices(), Q, 7052 MaxRecurse); 7053 } 7054 case Instruction::InsertElement: 7055 return simplifyInsertElementInst(NewOps[0], NewOps[1], NewOps[2], Q); 7056 case Instruction::ExtractValue: { 7057 auto *EVI = cast<ExtractValueInst>(I); 7058 return simplifyExtractValueInst(NewOps[0], EVI->getIndices(), Q, 7059 MaxRecurse); 7060 } 7061 case Instruction::ExtractElement: 7062 return simplifyExtractElementInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7063 case Instruction::ShuffleVector: { 7064 auto *SVI = cast<ShuffleVectorInst>(I); 7065 return simplifyShuffleVectorInst(NewOps[0], NewOps[1], 7066 SVI->getShuffleMask(), SVI->getType(), Q, 7067 MaxRecurse); 7068 } 7069 case Instruction::PHI: 7070 return simplifyPHINode(cast<PHINode>(I), NewOps, Q); 7071 case Instruction::Call: 7072 return simplifyCall( 7073 cast<CallInst>(I), NewOps.back(), 7074 NewOps.drop_back(1 + cast<CallInst>(I)->getNumTotalBundleOperands()), Q); 7075 case Instruction::Freeze: 7076 return llvm::simplifyFreezeInst(NewOps[0], Q); 7077 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc: 7078 #include "llvm/IR/Instruction.def" 7079 #undef HANDLE_CAST_INST 7080 return simplifyCastInst(I->getOpcode(), NewOps[0], I->getType(), Q, 7081 MaxRecurse); 7082 case Instruction::Alloca: 7083 // No simplifications for Alloca and it can't be constant folded. 7084 return nullptr; 7085 case Instruction::Load: 7086 return simplifyLoadInst(cast<LoadInst>(I), NewOps[0], Q); 7087 } 7088 } 7089 7090 Value *llvm::simplifyInstructionWithOperands(Instruction *I, 7091 ArrayRef<Value *> NewOps, 7092 const SimplifyQuery &SQ) { 7093 assert(NewOps.size() == I->getNumOperands() && 7094 "Number of operands should match the instruction!"); 7095 return ::simplifyInstructionWithOperands(I, NewOps, SQ, RecursionLimit); 7096 } 7097 7098 Value *llvm::simplifyInstruction(Instruction *I, const SimplifyQuery &SQ) { 7099 SmallVector<Value *, 8> Ops(I->operands()); 7100 Value *Result = ::simplifyInstructionWithOperands(I, Ops, SQ, RecursionLimit); 7101 7102 /// If called on unreachable code, the instruction may simplify to itself. 7103 /// Make life easier for users by detecting that case here, and returning a 7104 /// safe value instead. 7105 return Result == I ? UndefValue::get(I->getType()) : Result; 7106 } 7107 7108 /// Implementation of recursive simplification through an instruction's 7109 /// uses. 7110 /// 7111 /// This is the common implementation of the recursive simplification routines. 7112 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to 7113 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of 7114 /// instructions to process and attempt to simplify it using 7115 /// InstructionSimplify. Recursively visited users which could not be 7116 /// simplified themselves are to the optional UnsimplifiedUsers set for 7117 /// further processing by the caller. 7118 /// 7119 /// This routine returns 'true' only when *it* simplifies something. The passed 7120 /// in simplified value does not count toward this. 7121 static bool replaceAndRecursivelySimplifyImpl( 7122 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 7123 const DominatorTree *DT, AssumptionCache *AC, 7124 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) { 7125 bool Simplified = false; 7126 SmallSetVector<Instruction *, 8> Worklist; 7127 const DataLayout &DL = I->getModule()->getDataLayout(); 7128 7129 // If we have an explicit value to collapse to, do that round of the 7130 // simplification loop by hand initially. 7131 if (SimpleV) { 7132 for (User *U : I->users()) 7133 if (U != I) 7134 Worklist.insert(cast<Instruction>(U)); 7135 7136 // Replace the instruction with its simplified value. 7137 I->replaceAllUsesWith(SimpleV); 7138 7139 if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects()) 7140 I->eraseFromParent(); 7141 } else { 7142 Worklist.insert(I); 7143 } 7144 7145 // Note that we must test the size on each iteration, the worklist can grow. 7146 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { 7147 I = Worklist[Idx]; 7148 7149 // See if this instruction simplifies. 7150 SimpleV = simplifyInstruction(I, {DL, TLI, DT, AC}); 7151 if (!SimpleV) { 7152 if (UnsimplifiedUsers) 7153 UnsimplifiedUsers->insert(I); 7154 continue; 7155 } 7156 7157 Simplified = true; 7158 7159 // Stash away all the uses of the old instruction so we can check them for 7160 // recursive simplifications after a RAUW. This is cheaper than checking all 7161 // uses of To on the recursive step in most cases. 7162 for (User *U : I->users()) 7163 Worklist.insert(cast<Instruction>(U)); 7164 7165 // Replace the instruction with its simplified value. 7166 I->replaceAllUsesWith(SimpleV); 7167 7168 if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects()) 7169 I->eraseFromParent(); 7170 } 7171 return Simplified; 7172 } 7173 7174 bool llvm::replaceAndRecursivelySimplify( 7175 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 7176 const DominatorTree *DT, AssumptionCache *AC, 7177 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) { 7178 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!"); 7179 assert(SimpleV && "Must provide a simplified value."); 7180 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC, 7181 UnsimplifiedUsers); 7182 } 7183 7184 namespace llvm { 7185 const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) { 7186 auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>(); 7187 auto *DT = DTWP ? &DTWP->getDomTree() : nullptr; 7188 auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>(); 7189 auto *TLI = TLIWP ? &TLIWP->getTLI(F) : nullptr; 7190 auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>(); 7191 auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr; 7192 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 7193 } 7194 7195 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR, 7196 const DataLayout &DL) { 7197 return {DL, &AR.TLI, &AR.DT, &AR.AC}; 7198 } 7199 7200 template <class T, class... TArgs> 7201 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM, 7202 Function &F) { 7203 auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F); 7204 auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F); 7205 auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F); 7206 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 7207 } 7208 template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &, 7209 Function &); 7210 } // namespace llvm 7211 7212 void InstSimplifyFolder::anchor() {} 7213