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