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 #include "llvm/ADT/SetVector.h" 21 #include "llvm/ADT/Statistic.h" 22 #include "llvm/Analysis/AliasAnalysis.h" 23 #include "llvm/Analysis/AssumptionCache.h" 24 #include "llvm/Analysis/CaptureTracking.h" 25 #include "llvm/Analysis/CmpInstAnalysis.h" 26 #include "llvm/Analysis/ConstantFolding.h" 27 #include "llvm/Analysis/LoopAnalysisManager.h" 28 #include "llvm/Analysis/MemoryBuiltins.h" 29 #include "llvm/Analysis/OverflowInstAnalysis.h" 30 #include "llvm/Analysis/ValueTracking.h" 31 #include "llvm/Analysis/VectorUtils.h" 32 #include "llvm/IR/ConstantRange.h" 33 #include "llvm/IR/DataLayout.h" 34 #include "llvm/IR/Dominators.h" 35 #include "llvm/IR/GetElementPtrTypeIterator.h" 36 #include "llvm/IR/GlobalAlias.h" 37 #include "llvm/IR/InstrTypes.h" 38 #include "llvm/IR/Instructions.h" 39 #include "llvm/IR/Operator.h" 40 #include "llvm/IR/PatternMatch.h" 41 #include "llvm/IR/ValueHandle.h" 42 #include "llvm/Support/KnownBits.h" 43 #include <algorithm> 44 using namespace llvm; 45 using namespace llvm::PatternMatch; 46 47 #define DEBUG_TYPE "instsimplify" 48 49 enum { RecursionLimit = 3 }; 50 51 STATISTIC(NumExpand, "Number of expansions"); 52 STATISTIC(NumReassoc, "Number of reassociations"); 53 54 static Value *SimplifyAndInst(Value *, Value *, const SimplifyQuery &, unsigned); 55 static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned); 56 static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &, 57 const SimplifyQuery &, unsigned); 58 static Value *SimplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &, 59 unsigned); 60 static Value *SimplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &, 61 const SimplifyQuery &, unsigned); 62 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &, 63 unsigned); 64 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 65 const SimplifyQuery &Q, unsigned MaxRecurse); 66 static Value *SimplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned); 67 static Value *SimplifyXorInst(Value *, Value *, const SimplifyQuery &, unsigned); 68 static Value *SimplifyCastInst(unsigned, Value *, Type *, 69 const SimplifyQuery &, unsigned); 70 static Value *SimplifyGEPInst(Type *, ArrayRef<Value *>, const SimplifyQuery &, 71 unsigned); 72 static Value *SimplifySelectInst(Value *, Value *, Value *, 73 const SimplifyQuery &, unsigned); 74 75 static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal, 76 Value *FalseVal) { 77 BinaryOperator::BinaryOps BinOpCode; 78 if (auto *BO = dyn_cast<BinaryOperator>(Cond)) 79 BinOpCode = BO->getOpcode(); 80 else 81 return nullptr; 82 83 CmpInst::Predicate ExpectedPred, Pred1, Pred2; 84 if (BinOpCode == BinaryOperator::Or) { 85 ExpectedPred = ICmpInst::ICMP_NE; 86 } else if (BinOpCode == BinaryOperator::And) { 87 ExpectedPred = ICmpInst::ICMP_EQ; 88 } else 89 return nullptr; 90 91 // %A = icmp eq %TV, %FV 92 // %B = icmp eq %X, %Y (and one of these is a select operand) 93 // %C = and %A, %B 94 // %D = select %C, %TV, %FV 95 // --> 96 // %FV 97 98 // %A = icmp ne %TV, %FV 99 // %B = icmp ne %X, %Y (and one of these is a select operand) 100 // %C = or %A, %B 101 // %D = select %C, %TV, %FV 102 // --> 103 // %TV 104 Value *X, *Y; 105 if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal), 106 m_Specific(FalseVal)), 107 m_ICmp(Pred2, m_Value(X), m_Value(Y)))) || 108 Pred1 != Pred2 || Pred1 != ExpectedPred) 109 return nullptr; 110 111 if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal) 112 return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal; 113 114 return nullptr; 115 } 116 117 /// For a boolean type or a vector of boolean type, return false or a vector 118 /// with every element false. 119 static Constant *getFalse(Type *Ty) { 120 return ConstantInt::getFalse(Ty); 121 } 122 123 /// For a boolean type or a vector of boolean type, return true or a vector 124 /// with every element true. 125 static Constant *getTrue(Type *Ty) { 126 return ConstantInt::getTrue(Ty); 127 } 128 129 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? 130 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, 131 Value *RHS) { 132 CmpInst *Cmp = dyn_cast<CmpInst>(V); 133 if (!Cmp) 134 return false; 135 CmpInst::Predicate CPred = Cmp->getPredicate(); 136 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); 137 if (CPred == Pred && CLHS == LHS && CRHS == RHS) 138 return true; 139 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && 140 CRHS == LHS; 141 } 142 143 /// Simplify comparison with true or false branch of select: 144 /// %sel = select i1 %cond, i32 %tv, i32 %fv 145 /// %cmp = icmp sle i32 %sel, %rhs 146 /// Compose new comparison by substituting %sel with either %tv or %fv 147 /// and see if it simplifies. 148 static Value *simplifyCmpSelCase(CmpInst::Predicate Pred, Value *LHS, 149 Value *RHS, Value *Cond, 150 const SimplifyQuery &Q, unsigned MaxRecurse, 151 Constant *TrueOrFalse) { 152 Value *SimplifiedCmp = SimplifyCmpInst(Pred, LHS, RHS, Q, MaxRecurse); 153 if (SimplifiedCmp == Cond) { 154 // %cmp simplified to the select condition (%cond). 155 return TrueOrFalse; 156 } else if (!SimplifiedCmp && isSameCompare(Cond, Pred, LHS, RHS)) { 157 // It didn't simplify. However, if composed comparison is equivalent 158 // to the select condition (%cond) then we can replace it. 159 return TrueOrFalse; 160 } 161 return SimplifiedCmp; 162 } 163 164 /// Simplify comparison with true branch of select 165 static Value *simplifyCmpSelTrueCase(CmpInst::Predicate Pred, Value *LHS, 166 Value *RHS, Value *Cond, 167 const SimplifyQuery &Q, 168 unsigned MaxRecurse) { 169 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 170 getTrue(Cond->getType())); 171 } 172 173 /// Simplify comparison with false branch of select 174 static Value *simplifyCmpSelFalseCase(CmpInst::Predicate Pred, Value *LHS, 175 Value *RHS, Value *Cond, 176 const SimplifyQuery &Q, 177 unsigned MaxRecurse) { 178 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 179 getFalse(Cond->getType())); 180 } 181 182 /// We know comparison with both branches of select can be simplified, but they 183 /// are not equal. This routine handles some logical simplifications. 184 static Value *handleOtherCmpSelSimplifications(Value *TCmp, Value *FCmp, 185 Value *Cond, 186 const SimplifyQuery &Q, 187 unsigned MaxRecurse) { 188 // If the false value simplified to false, then the result of the compare 189 // is equal to "Cond && TCmp". This also catches the case when the false 190 // value simplified to false and the true value to true, returning "Cond". 191 if (match(FCmp, m_Zero())) 192 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse)) 193 return V; 194 // If the true value simplified to true, then the result of the compare 195 // is equal to "Cond || FCmp". 196 if (match(TCmp, m_One())) 197 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse)) 198 return V; 199 // Finally, if the false value simplified to true and the true value to 200 // false, then the result of the compare is equal to "!Cond". 201 if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 202 if (Value *V = SimplifyXorInst( 203 Cond, Constant::getAllOnesValue(Cond->getType()), Q, MaxRecurse)) 204 return V; 205 return nullptr; 206 } 207 208 /// Does the given value dominate the specified phi node? 209 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 210 Instruction *I = dyn_cast<Instruction>(V); 211 if (!I) 212 // Arguments and constants dominate all instructions. 213 return true; 214 215 // If we are processing instructions (and/or basic blocks) that have not been 216 // fully added to a function, the parent nodes may still be null. Simply 217 // return the conservative answer in these cases. 218 if (!I->getParent() || !P->getParent() || !I->getFunction()) 219 return false; 220 221 // If we have a DominatorTree then do a precise test. 222 if (DT) 223 return DT->dominates(I, P); 224 225 // Otherwise, if the instruction is in the entry block and is not an invoke, 226 // then it obviously dominates all phi nodes. 227 if (I->getParent()->isEntryBlock() && !isa<InvokeInst>(I) && 228 !isa<CallBrInst>(I)) 229 return true; 230 231 return false; 232 } 233 234 /// Try to simplify a binary operator of form "V op OtherOp" where V is 235 /// "(B0 opex B1)" by distributing 'op' across 'opex' as 236 /// "(B0 op OtherOp) opex (B1 op OtherOp)". 237 static Value *expandBinOp(Instruction::BinaryOps Opcode, Value *V, 238 Value *OtherOp, Instruction::BinaryOps OpcodeToExpand, 239 const SimplifyQuery &Q, unsigned MaxRecurse) { 240 auto *B = dyn_cast<BinaryOperator>(V); 241 if (!B || B->getOpcode() != OpcodeToExpand) 242 return nullptr; 243 Value *B0 = B->getOperand(0), *B1 = B->getOperand(1); 244 Value *L = SimplifyBinOp(Opcode, B0, OtherOp, Q.getWithoutUndef(), 245 MaxRecurse); 246 if (!L) 247 return nullptr; 248 Value *R = SimplifyBinOp(Opcode, B1, OtherOp, Q.getWithoutUndef(), 249 MaxRecurse); 250 if (!R) 251 return nullptr; 252 253 // Does the expanded pair of binops simplify to the existing binop? 254 if ((L == B0 && R == B1) || 255 (Instruction::isCommutative(OpcodeToExpand) && L == B1 && R == B0)) { 256 ++NumExpand; 257 return B; 258 } 259 260 // Otherwise, return "L op' R" if it simplifies. 261 Value *S = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse); 262 if (!S) 263 return nullptr; 264 265 ++NumExpand; 266 return S; 267 } 268 269 /// Try to simplify binops of form "A op (B op' C)" or the commuted variant by 270 /// distributing op over op'. 271 static Value *expandCommutativeBinOp(Instruction::BinaryOps Opcode, 272 Value *L, Value *R, 273 Instruction::BinaryOps OpcodeToExpand, 274 const SimplifyQuery &Q, 275 unsigned MaxRecurse) { 276 // Recursion is always used, so bail out at once if we already hit the limit. 277 if (!MaxRecurse--) 278 return nullptr; 279 280 if (Value *V = expandBinOp(Opcode, L, R, OpcodeToExpand, Q, MaxRecurse)) 281 return V; 282 if (Value *V = expandBinOp(Opcode, R, L, OpcodeToExpand, Q, MaxRecurse)) 283 return V; 284 return nullptr; 285 } 286 287 /// Generic simplifications for associative binary operations. 288 /// Returns the simpler value, or null if none was found. 289 static Value *SimplifyAssociativeBinOp(Instruction::BinaryOps Opcode, 290 Value *LHS, Value *RHS, 291 const SimplifyQuery &Q, 292 unsigned MaxRecurse) { 293 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 294 295 // Recursion is always used, so bail out at once if we already hit the limit. 296 if (!MaxRecurse--) 297 return nullptr; 298 299 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 300 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 301 302 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 303 if (Op0 && Op0->getOpcode() == Opcode) { 304 Value *A = Op0->getOperand(0); 305 Value *B = Op0->getOperand(1); 306 Value *C = RHS; 307 308 // Does "B op C" simplify? 309 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 310 // It does! Return "A op V" if it simplifies or is already available. 311 // If V equals B then "A op V" is just the LHS. 312 if (V == B) return LHS; 313 // Otherwise return "A op V" if it simplifies. 314 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { 315 ++NumReassoc; 316 return W; 317 } 318 } 319 } 320 321 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 322 if (Op1 && Op1->getOpcode() == Opcode) { 323 Value *A = LHS; 324 Value *B = Op1->getOperand(0); 325 Value *C = Op1->getOperand(1); 326 327 // Does "A op B" simplify? 328 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { 329 // It does! Return "V op C" if it simplifies or is already available. 330 // If V equals B then "V op C" is just the RHS. 331 if (V == B) return RHS; 332 // Otherwise return "V op C" if it simplifies. 333 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { 334 ++NumReassoc; 335 return W; 336 } 337 } 338 } 339 340 // The remaining transforms require commutativity as well as associativity. 341 if (!Instruction::isCommutative(Opcode)) 342 return nullptr; 343 344 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 345 if (Op0 && Op0->getOpcode() == Opcode) { 346 Value *A = Op0->getOperand(0); 347 Value *B = Op0->getOperand(1); 348 Value *C = RHS; 349 350 // Does "C op A" simplify? 351 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 352 // It does! Return "V op B" if it simplifies or is already available. 353 // If V equals A then "V op B" is just the LHS. 354 if (V == A) return LHS; 355 // Otherwise return "V op B" if it simplifies. 356 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { 357 ++NumReassoc; 358 return W; 359 } 360 } 361 } 362 363 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 364 if (Op1 && Op1->getOpcode() == Opcode) { 365 Value *A = LHS; 366 Value *B = Op1->getOperand(0); 367 Value *C = Op1->getOperand(1); 368 369 // Does "C op A" simplify? 370 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 371 // It does! Return "B op V" if it simplifies or is already available. 372 // If V equals C then "B op V" is just the RHS. 373 if (V == C) return RHS; 374 // Otherwise return "B op V" if it simplifies. 375 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { 376 ++NumReassoc; 377 return W; 378 } 379 } 380 } 381 382 return nullptr; 383 } 384 385 /// In the case of a binary operation with a select instruction as an operand, 386 /// try to simplify the binop by seeing whether evaluating it on both branches 387 /// of the select results in the same value. Returns the common value if so, 388 /// otherwise returns null. 389 static Value *ThreadBinOpOverSelect(Instruction::BinaryOps Opcode, Value *LHS, 390 Value *RHS, const SimplifyQuery &Q, 391 unsigned MaxRecurse) { 392 // Recursion is always used, so bail out at once if we already hit the limit. 393 if (!MaxRecurse--) 394 return nullptr; 395 396 SelectInst *SI; 397 if (isa<SelectInst>(LHS)) { 398 SI = cast<SelectInst>(LHS); 399 } else { 400 assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 401 SI = cast<SelectInst>(RHS); 402 } 403 404 // Evaluate the BinOp on the true and false branches of the select. 405 Value *TV; 406 Value *FV; 407 if (SI == LHS) { 408 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); 409 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); 410 } else { 411 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); 412 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); 413 } 414 415 // If they simplified to the same value, then return the common value. 416 // If they both failed to simplify then return null. 417 if (TV == FV) 418 return TV; 419 420 // If one branch simplified to undef, return the other one. 421 if (TV && Q.isUndefValue(TV)) 422 return FV; 423 if (FV && Q.isUndefValue(FV)) 424 return TV; 425 426 // If applying the operation did not change the true and false select values, 427 // then the result of the binop is the select itself. 428 if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 429 return SI; 430 431 // If one branch simplified and the other did not, and the simplified 432 // value is equal to the unsimplified one, return the simplified value. 433 // For example, select (cond, X, X & Z) & Z -> X & Z. 434 if ((FV && !TV) || (TV && !FV)) { 435 // Check that the simplified value has the form "X op Y" where "op" is the 436 // same as the original operation. 437 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 438 if (Simplified && Simplified->getOpcode() == unsigned(Opcode)) { 439 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 440 // We already know that "op" is the same as for the simplified value. See 441 // if the operands match too. If so, return the simplified value. 442 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 443 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 444 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 445 if (Simplified->getOperand(0) == UnsimplifiedLHS && 446 Simplified->getOperand(1) == UnsimplifiedRHS) 447 return Simplified; 448 if (Simplified->isCommutative() && 449 Simplified->getOperand(1) == UnsimplifiedLHS && 450 Simplified->getOperand(0) == UnsimplifiedRHS) 451 return Simplified; 452 } 453 } 454 455 return nullptr; 456 } 457 458 /// In the case of a comparison with a select instruction, try to simplify the 459 /// comparison by seeing whether both branches of the select result in the same 460 /// value. Returns the common value if so, otherwise returns null. 461 /// For example, if we have: 462 /// %tmp = select i1 %cmp, i32 1, i32 2 463 /// %cmp1 = icmp sle i32 %tmp, 3 464 /// We can simplify %cmp1 to true, because both branches of select are 465 /// less than 3. We compose new comparison by substituting %tmp with both 466 /// branches of select and see if it can be simplified. 467 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 468 Value *RHS, const SimplifyQuery &Q, 469 unsigned MaxRecurse) { 470 // Recursion is always used, so bail out at once if we already hit the limit. 471 if (!MaxRecurse--) 472 return nullptr; 473 474 // Make sure the select is on the LHS. 475 if (!isa<SelectInst>(LHS)) { 476 std::swap(LHS, RHS); 477 Pred = CmpInst::getSwappedPredicate(Pred); 478 } 479 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 480 SelectInst *SI = cast<SelectInst>(LHS); 481 Value *Cond = SI->getCondition(); 482 Value *TV = SI->getTrueValue(); 483 Value *FV = SI->getFalseValue(); 484 485 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 486 // Does "cmp TV, RHS" simplify? 487 Value *TCmp = simplifyCmpSelTrueCase(Pred, TV, RHS, Cond, Q, MaxRecurse); 488 if (!TCmp) 489 return nullptr; 490 491 // Does "cmp FV, RHS" simplify? 492 Value *FCmp = simplifyCmpSelFalseCase(Pred, FV, RHS, Cond, Q, MaxRecurse); 493 if (!FCmp) 494 return nullptr; 495 496 // If both sides simplified to the same value, then use it as the result of 497 // the original comparison. 498 if (TCmp == FCmp) 499 return TCmp; 500 501 // The remaining cases only make sense if the select condition has the same 502 // type as the result of the comparison, so bail out if this is not so. 503 if (Cond->getType()->isVectorTy() == RHS->getType()->isVectorTy()) 504 return handleOtherCmpSelSimplifications(TCmp, FCmp, Cond, Q, MaxRecurse); 505 506 return nullptr; 507 } 508 509 /// In the case of a binary operation with an operand that is a PHI instruction, 510 /// try to simplify the binop by seeing whether evaluating it on the incoming 511 /// phi values yields the same result for every value. If so returns the common 512 /// value, otherwise returns null. 513 static Value *ThreadBinOpOverPHI(Instruction::BinaryOps Opcode, Value *LHS, 514 Value *RHS, const SimplifyQuery &Q, 515 unsigned MaxRecurse) { 516 // Recursion is always used, so bail out at once if we already hit the limit. 517 if (!MaxRecurse--) 518 return nullptr; 519 520 PHINode *PI; 521 if (isa<PHINode>(LHS)) { 522 PI = cast<PHINode>(LHS); 523 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 524 if (!valueDominatesPHI(RHS, PI, Q.DT)) 525 return nullptr; 526 } else { 527 assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 528 PI = cast<PHINode>(RHS); 529 // Bail out if LHS and the phi may be mutually interdependent due to a loop. 530 if (!valueDominatesPHI(LHS, PI, Q.DT)) 531 return nullptr; 532 } 533 534 // Evaluate the BinOp on the incoming phi values. 535 Value *CommonValue = nullptr; 536 for (Value *Incoming : PI->incoming_values()) { 537 // If the incoming value is the phi node itself, it can safely be skipped. 538 if (Incoming == PI) continue; 539 Value *V = PI == LHS ? 540 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) : 541 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse); 542 // If the operation failed to simplify, or simplified to a different value 543 // to previously, then give up. 544 if (!V || (CommonValue && V != CommonValue)) 545 return nullptr; 546 CommonValue = V; 547 } 548 549 return CommonValue; 550 } 551 552 /// In the case of a comparison with a PHI instruction, try to simplify the 553 /// comparison by seeing whether comparing with all of the incoming phi values 554 /// yields the same result every time. If so returns the common result, 555 /// otherwise returns null. 556 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 557 const SimplifyQuery &Q, unsigned MaxRecurse) { 558 // Recursion is always used, so bail out at once if we already hit the limit. 559 if (!MaxRecurse--) 560 return nullptr; 561 562 // Make sure the phi is on the LHS. 563 if (!isa<PHINode>(LHS)) { 564 std::swap(LHS, RHS); 565 Pred = CmpInst::getSwappedPredicate(Pred); 566 } 567 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 568 PHINode *PI = cast<PHINode>(LHS); 569 570 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 571 if (!valueDominatesPHI(RHS, PI, Q.DT)) 572 return nullptr; 573 574 // Evaluate the BinOp on the incoming phi values. 575 Value *CommonValue = nullptr; 576 for (unsigned u = 0, e = PI->getNumIncomingValues(); u < e; ++u) { 577 Value *Incoming = PI->getIncomingValue(u); 578 Instruction *InTI = PI->getIncomingBlock(u)->getTerminator(); 579 // If the incoming value is the phi node itself, it can safely be skipped. 580 if (Incoming == PI) continue; 581 // Change the context instruction to the "edge" that flows into the phi. 582 // This is important because that is where incoming is actually "evaluated" 583 // even though it is used later somewhere else. 584 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q.getWithInstruction(InTI), 585 MaxRecurse); 586 // If the operation failed to simplify, or simplified to a different value 587 // to previously, then give up. 588 if (!V || (CommonValue && V != CommonValue)) 589 return nullptr; 590 CommonValue = V; 591 } 592 593 return CommonValue; 594 } 595 596 static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode, 597 Value *&Op0, Value *&Op1, 598 const SimplifyQuery &Q) { 599 if (auto *CLHS = dyn_cast<Constant>(Op0)) { 600 if (auto *CRHS = dyn_cast<Constant>(Op1)) 601 return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL); 602 603 // Canonicalize the constant to the RHS if this is a commutative operation. 604 if (Instruction::isCommutative(Opcode)) 605 std::swap(Op0, Op1); 606 } 607 return nullptr; 608 } 609 610 /// Given operands for an Add, see if we can fold the result. 611 /// If not, this returns null. 612 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 613 const SimplifyQuery &Q, unsigned MaxRecurse) { 614 if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q)) 615 return C; 616 617 // X + undef -> undef 618 if (Q.isUndefValue(Op1)) 619 return Op1; 620 621 // X + 0 -> X 622 if (match(Op1, m_Zero())) 623 return Op0; 624 625 // If two operands are negative, return 0. 626 if (isKnownNegation(Op0, Op1)) 627 return Constant::getNullValue(Op0->getType()); 628 629 // X + (Y - X) -> Y 630 // (Y - X) + X -> Y 631 // Eg: X + -X -> 0 632 Value *Y = nullptr; 633 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 634 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 635 return Y; 636 637 // X + ~X -> -1 since ~X = -X-1 638 Type *Ty = Op0->getType(); 639 if (match(Op0, m_Not(m_Specific(Op1))) || 640 match(Op1, m_Not(m_Specific(Op0)))) 641 return Constant::getAllOnesValue(Ty); 642 643 // add nsw/nuw (xor Y, signmask), signmask --> Y 644 // The no-wrapping add guarantees that the top bit will be set by the add. 645 // Therefore, the xor must be clearing the already set sign bit of Y. 646 if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) && 647 match(Op0, m_Xor(m_Value(Y), m_SignMask()))) 648 return Y; 649 650 // add nuw %x, -1 -> -1, because %x can only be 0. 651 if (IsNUW && match(Op1, m_AllOnes())) 652 return Op1; // Which is -1. 653 654 /// i1 add -> xor. 655 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 656 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 657 return V; 658 659 // Try some generic simplifications for associative operations. 660 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, 661 MaxRecurse)) 662 return V; 663 664 // Threading Add over selects and phi nodes is pointless, so don't bother. 665 // Threading over the select in "A + select(cond, B, C)" means evaluating 666 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 667 // only if B and C are equal. If B and C are equal then (since we assume 668 // that operands have already been simplified) "select(cond, B, C)" should 669 // have been simplified to the common value of B and C already. Analysing 670 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 671 // for threading over phi nodes. 672 673 return nullptr; 674 } 675 676 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 677 const SimplifyQuery &Query) { 678 return ::SimplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit); 679 } 680 681 /// Compute the base pointer and cumulative constant offsets for V. 682 /// 683 /// This strips all constant offsets off of V, leaving it the base pointer, and 684 /// accumulates the total constant offset applied in the returned constant. It 685 /// returns 0 if V is not a pointer, and returns the constant '0' if there are 686 /// no constant offsets applied. 687 /// 688 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't 689 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc. 690 /// folding. 691 static Constant *stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V, 692 bool AllowNonInbounds = false) { 693 assert(V->getType()->isPtrOrPtrVectorTy()); 694 695 Type *IntIdxTy = DL.getIndexType(V->getType())->getScalarType(); 696 APInt Offset = APInt::getNullValue(IntIdxTy->getIntegerBitWidth()); 697 698 V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds); 699 // As that strip may trace through `addrspacecast`, need to sext or trunc 700 // the offset calculated. 701 IntIdxTy = DL.getIndexType(V->getType())->getScalarType(); 702 Offset = Offset.sextOrTrunc(IntIdxTy->getIntegerBitWidth()); 703 704 Constant *OffsetIntPtr = ConstantInt::get(IntIdxTy, Offset); 705 if (VectorType *VecTy = dyn_cast<VectorType>(V->getType())) 706 return ConstantVector::getSplat(VecTy->getElementCount(), OffsetIntPtr); 707 return OffsetIntPtr; 708 } 709 710 /// Compute the constant difference between two pointer values. 711 /// If the difference is not a constant, returns zero. 712 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS, 713 Value *RHS) { 714 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS); 715 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS); 716 717 // If LHS and RHS are not related via constant offsets to the same base 718 // value, there is nothing we can do here. 719 if (LHS != RHS) 720 return nullptr; 721 722 // Otherwise, the difference of LHS - RHS can be computed as: 723 // LHS - RHS 724 // = (LHSOffset + Base) - (RHSOffset + Base) 725 // = LHSOffset - RHSOffset 726 return ConstantExpr::getSub(LHSOffset, RHSOffset); 727 } 728 729 /// Given operands for a Sub, see if we can fold the result. 730 /// If not, this returns null. 731 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 732 const SimplifyQuery &Q, unsigned MaxRecurse) { 733 if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q)) 734 return C; 735 736 // X - undef -> undef 737 // undef - X -> undef 738 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 739 return UndefValue::get(Op0->getType()); 740 741 // X - 0 -> X 742 if (match(Op1, m_Zero())) 743 return Op0; 744 745 // X - X -> 0 746 if (Op0 == Op1) 747 return Constant::getNullValue(Op0->getType()); 748 749 // Is this a negation? 750 if (match(Op0, m_Zero())) { 751 // 0 - X -> 0 if the sub is NUW. 752 if (isNUW) 753 return Constant::getNullValue(Op0->getType()); 754 755 KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 756 if (Known.Zero.isMaxSignedValue()) { 757 // Op1 is either 0 or the minimum signed value. If the sub is NSW, then 758 // Op1 must be 0 because negating the minimum signed value is undefined. 759 if (isNSW) 760 return Constant::getNullValue(Op0->getType()); 761 762 // 0 - X -> X if X is 0 or the minimum signed value. 763 return Op1; 764 } 765 } 766 767 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 768 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 769 Value *X = nullptr, *Y = nullptr, *Z = Op1; 770 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 771 // See if "V === Y - Z" simplifies. 772 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1)) 773 // It does! Now see if "X + V" simplifies. 774 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) { 775 // It does, we successfully reassociated! 776 ++NumReassoc; 777 return W; 778 } 779 // See if "V === X - Z" simplifies. 780 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 781 // It does! Now see if "Y + V" simplifies. 782 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) { 783 // It does, we successfully reassociated! 784 ++NumReassoc; 785 return W; 786 } 787 } 788 789 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 790 // For example, X - (X + 1) -> -1 791 X = Op0; 792 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 793 // See if "V === X - Y" simplifies. 794 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 795 // It does! Now see if "V - Z" simplifies. 796 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) { 797 // It does, we successfully reassociated! 798 ++NumReassoc; 799 return W; 800 } 801 // See if "V === X - Z" simplifies. 802 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 803 // It does! Now see if "V - Y" simplifies. 804 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) { 805 // It does, we successfully reassociated! 806 ++NumReassoc; 807 return W; 808 } 809 } 810 811 // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 812 // For example, X - (X - Y) -> Y. 813 Z = Op0; 814 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 815 // See if "V === Z - X" simplifies. 816 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1)) 817 // It does! Now see if "V + Y" simplifies. 818 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) { 819 // It does, we successfully reassociated! 820 ++NumReassoc; 821 return W; 822 } 823 824 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. 825 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && 826 match(Op1, m_Trunc(m_Value(Y)))) 827 if (X->getType() == Y->getType()) 828 // See if "V === X - Y" simplifies. 829 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 830 // It does! Now see if "trunc V" simplifies. 831 if (Value *W = SimplifyCastInst(Instruction::Trunc, V, Op0->getType(), 832 Q, MaxRecurse - 1)) 833 // It does, return the simplified "trunc V". 834 return W; 835 836 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). 837 if (match(Op0, m_PtrToInt(m_Value(X))) && 838 match(Op1, m_PtrToInt(m_Value(Y)))) 839 if (Constant *Result = computePointerDifference(Q.DL, X, Y)) 840 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true); 841 842 // i1 sub -> xor. 843 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 844 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 845 return V; 846 847 // Threading Sub over selects and phi nodes is pointless, so don't bother. 848 // Threading over the select in "A - select(cond, B, C)" means evaluating 849 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 850 // only if B and C are equal. If B and C are equal then (since we assume 851 // that operands have already been simplified) "select(cond, B, C)" should 852 // have been simplified to the common value of B and C already. Analysing 853 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 854 // for threading over phi nodes. 855 856 return nullptr; 857 } 858 859 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 860 const SimplifyQuery &Q) { 861 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit); 862 } 863 864 /// Given operands for a Mul, see if we can fold the result. 865 /// If not, this returns null. 866 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 867 unsigned MaxRecurse) { 868 if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q)) 869 return C; 870 871 // X * undef -> 0 872 // X * 0 -> 0 873 if (Q.isUndefValue(Op1) || match(Op1, m_Zero())) 874 return Constant::getNullValue(Op0->getType()); 875 876 // X * 1 -> X 877 if (match(Op1, m_One())) 878 return Op0; 879 880 // (X / Y) * Y -> X if the division is exact. 881 Value *X = nullptr; 882 if (Q.IIQ.UseInstrInfo && 883 (match(Op0, 884 m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y 885 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))) // Y * (X / Y) 886 return X; 887 888 // i1 mul -> and. 889 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 890 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1)) 891 return V; 892 893 // Try some generic simplifications for associative operations. 894 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, 895 MaxRecurse)) 896 return V; 897 898 // Mul distributes over Add. Try some generic simplifications based on this. 899 if (Value *V = expandCommutativeBinOp(Instruction::Mul, Op0, Op1, 900 Instruction::Add, Q, MaxRecurse)) 901 return V; 902 903 // If the operation is with the result of a select instruction, check whether 904 // operating on either branch of the select always yields the same value. 905 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 906 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, 907 MaxRecurse)) 908 return V; 909 910 // If the operation is with the result of a phi instruction, check whether 911 // operating on all incoming values of the phi always yields the same value. 912 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 913 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, 914 MaxRecurse)) 915 return V; 916 917 return nullptr; 918 } 919 920 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 921 return ::SimplifyMulInst(Op0, Op1, Q, RecursionLimit); 922 } 923 924 /// Check for common or similar folds of integer division or integer remainder. 925 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem). 926 static Value *simplifyDivRem(Instruction::BinaryOps Opcode, Value *Op0, 927 Value *Op1, const SimplifyQuery &Q) { 928 bool IsDiv = (Opcode == Instruction::SDiv || Opcode == Instruction::UDiv); 929 bool IsSigned = (Opcode == Instruction::SDiv || Opcode == Instruction::SRem); 930 931 Type *Ty = Op0->getType(); 932 933 // X / undef -> poison 934 // X % undef -> poison 935 if (Q.isUndefValue(Op1)) 936 return PoisonValue::get(Ty); 937 938 // X / 0 -> poison 939 // X % 0 -> poison 940 // We don't need to preserve faults! 941 if (match(Op1, m_Zero())) 942 return PoisonValue::get(Ty); 943 944 // If any element of a constant divisor fixed width vector is zero or undef 945 // the behavior is undefined and we can fold the whole op to poison. 946 auto *Op1C = dyn_cast<Constant>(Op1); 947 auto *VTy = dyn_cast<FixedVectorType>(Ty); 948 if (Op1C && VTy) { 949 unsigned NumElts = VTy->getNumElements(); 950 for (unsigned i = 0; i != NumElts; ++i) { 951 Constant *Elt = Op1C->getAggregateElement(i); 952 if (Elt && (Elt->isNullValue() || Q.isUndefValue(Elt))) 953 return PoisonValue::get(Ty); 954 } 955 } 956 957 // undef / X -> 0 958 // undef % X -> 0 959 if (Q.isUndefValue(Op0)) 960 return Constant::getNullValue(Ty); 961 962 // 0 / X -> 0 963 // 0 % X -> 0 964 if (match(Op0, m_Zero())) 965 return Constant::getNullValue(Op0->getType()); 966 967 // X / X -> 1 968 // X % X -> 0 969 if (Op0 == Op1) 970 return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty); 971 972 // X / 1 -> X 973 // X % 1 -> 0 974 // If this is a boolean op (single-bit element type), we can't have 975 // division-by-zero or remainder-by-zero, so assume the divisor is 1. 976 // Similarly, if we're zero-extending a boolean divisor, then assume it's a 1. 977 Value *X; 978 if (match(Op1, m_One()) || Ty->isIntOrIntVectorTy(1) || 979 (match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) 980 return IsDiv ? Op0 : Constant::getNullValue(Ty); 981 982 // If X * Y does not overflow, then: 983 // X * Y / Y -> X 984 // X * Y % Y -> 0 985 if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) { 986 auto *Mul = cast<OverflowingBinaryOperator>(Op0); 987 // The multiplication can't overflow if it is defined not to, or if 988 // X == A / Y for some A. 989 if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) || 990 (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)) || 991 (IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) || 992 (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) { 993 return IsDiv ? X : Constant::getNullValue(Op0->getType()); 994 } 995 } 996 997 return nullptr; 998 } 999 1000 /// Given a predicate and two operands, return true if the comparison is true. 1001 /// This is a helper for div/rem simplification where we return some other value 1002 /// when we can prove a relationship between the operands. 1003 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS, 1004 const SimplifyQuery &Q, unsigned MaxRecurse) { 1005 Value *V = SimplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse); 1006 Constant *C = dyn_cast_or_null<Constant>(V); 1007 return (C && C->isAllOnesValue()); 1008 } 1009 1010 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer 1011 /// to simplify X % Y to X. 1012 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q, 1013 unsigned MaxRecurse, bool IsSigned) { 1014 // Recursion is always used, so bail out at once if we already hit the limit. 1015 if (!MaxRecurse--) 1016 return false; 1017 1018 if (IsSigned) { 1019 // |X| / |Y| --> 0 1020 // 1021 // We require that 1 operand is a simple constant. That could be extended to 1022 // 2 variables if we computed the sign bit for each. 1023 // 1024 // Make sure that a constant is not the minimum signed value because taking 1025 // the abs() of that is undefined. 1026 Type *Ty = X->getType(); 1027 const APInt *C; 1028 if (match(X, m_APInt(C)) && !C->isMinSignedValue()) { 1029 // Is the variable divisor magnitude always greater than the constant 1030 // dividend magnitude? 1031 // |Y| > |C| --> Y < -abs(C) or Y > abs(C) 1032 Constant *PosDividendC = ConstantInt::get(Ty, C->abs()); 1033 Constant *NegDividendC = ConstantInt::get(Ty, -C->abs()); 1034 if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) || 1035 isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse)) 1036 return true; 1037 } 1038 if (match(Y, m_APInt(C))) { 1039 // Special-case: we can't take the abs() of a minimum signed value. If 1040 // that's the divisor, then all we have to do is prove that the dividend 1041 // is also not the minimum signed value. 1042 if (C->isMinSignedValue()) 1043 return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse); 1044 1045 // Is the variable dividend magnitude always less than the constant 1046 // divisor magnitude? 1047 // |X| < |C| --> X > -abs(C) and X < abs(C) 1048 Constant *PosDivisorC = ConstantInt::get(Ty, C->abs()); 1049 Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs()); 1050 if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) && 1051 isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse)) 1052 return true; 1053 } 1054 return false; 1055 } 1056 1057 // IsSigned == false. 1058 // Is the dividend unsigned less than the divisor? 1059 return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse); 1060 } 1061 1062 /// These are simplifications common to SDiv and UDiv. 1063 static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1064 const SimplifyQuery &Q, unsigned MaxRecurse) { 1065 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1066 return C; 1067 1068 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q)) 1069 return V; 1070 1071 bool IsSigned = Opcode == Instruction::SDiv; 1072 1073 // (X rem Y) / Y -> 0 1074 if ((IsSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || 1075 (!IsSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1))))) 1076 return Constant::getNullValue(Op0->getType()); 1077 1078 // (X /u C1) /u C2 -> 0 if C1 * C2 overflow 1079 ConstantInt *C1, *C2; 1080 if (!IsSigned && match(Op0, m_UDiv(m_Value(), m_ConstantInt(C1))) && 1081 match(Op1, m_ConstantInt(C2))) { 1082 bool Overflow; 1083 (void)C1->getValue().umul_ov(C2->getValue(), Overflow); 1084 if (Overflow) 1085 return Constant::getNullValue(Op0->getType()); 1086 } 1087 1088 // If the operation is with the result of a select instruction, check whether 1089 // operating on either branch of the select always yields the same value. 1090 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1091 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1092 return V; 1093 1094 // If the operation is with the result of a phi instruction, check whether 1095 // operating on all incoming values of the phi always yields the same value. 1096 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1097 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1098 return V; 1099 1100 if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned)) 1101 return Constant::getNullValue(Op0->getType()); 1102 1103 return nullptr; 1104 } 1105 1106 /// These are simplifications common to SRem and URem. 1107 static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1108 const SimplifyQuery &Q, unsigned MaxRecurse) { 1109 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1110 return C; 1111 1112 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q)) 1113 return V; 1114 1115 // (X % Y) % Y -> X % Y 1116 if ((Opcode == Instruction::SRem && 1117 match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || 1118 (Opcode == Instruction::URem && 1119 match(Op0, m_URem(m_Value(), m_Specific(Op1))))) 1120 return Op0; 1121 1122 // (X << Y) % X -> 0 1123 if (Q.IIQ.UseInstrInfo && 1124 ((Opcode == Instruction::SRem && 1125 match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) || 1126 (Opcode == Instruction::URem && 1127 match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))) 1128 return Constant::getNullValue(Op0->getType()); 1129 1130 // If the operation is with the result of a select instruction, check whether 1131 // operating on either branch of the select always yields the same value. 1132 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1133 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1134 return V; 1135 1136 // If the operation is with the result of a phi instruction, check whether 1137 // operating on all incoming values of the phi always yields the same value. 1138 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1139 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1140 return V; 1141 1142 // If X / Y == 0, then X % Y == X. 1143 if (isDivZero(Op0, Op1, Q, MaxRecurse, Opcode == Instruction::SRem)) 1144 return Op0; 1145 1146 return nullptr; 1147 } 1148 1149 /// Given operands for an SDiv, see if we can fold the result. 1150 /// If not, this returns null. 1151 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1152 unsigned MaxRecurse) { 1153 // If two operands are negated and no signed overflow, return -1. 1154 if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true)) 1155 return Constant::getAllOnesValue(Op0->getType()); 1156 1157 return simplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse); 1158 } 1159 1160 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1161 return ::SimplifySDivInst(Op0, Op1, Q, RecursionLimit); 1162 } 1163 1164 /// Given operands for a UDiv, see if we can fold the result. 1165 /// If not, this returns null. 1166 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1167 unsigned MaxRecurse) { 1168 return simplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse); 1169 } 1170 1171 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1172 return ::SimplifyUDivInst(Op0, Op1, Q, RecursionLimit); 1173 } 1174 1175 /// Given operands for an SRem, see if we can fold the result. 1176 /// If not, this returns null. 1177 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1178 unsigned MaxRecurse) { 1179 // If the divisor is 0, the result is undefined, so assume the divisor is -1. 1180 // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0 1181 Value *X; 1182 if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) 1183 return ConstantInt::getNullValue(Op0->getType()); 1184 1185 // If the two operands are negated, return 0. 1186 if (isKnownNegation(Op0, Op1)) 1187 return ConstantInt::getNullValue(Op0->getType()); 1188 1189 return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse); 1190 } 1191 1192 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1193 return ::SimplifySRemInst(Op0, Op1, Q, RecursionLimit); 1194 } 1195 1196 /// Given operands for a URem, see if we can fold the result. 1197 /// If not, this returns null. 1198 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1199 unsigned MaxRecurse) { 1200 return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse); 1201 } 1202 1203 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1204 return ::SimplifyURemInst(Op0, Op1, Q, RecursionLimit); 1205 } 1206 1207 /// Returns true if a shift by \c Amount always yields poison. 1208 static bool isPoisonShift(Value *Amount, const SimplifyQuery &Q) { 1209 Constant *C = dyn_cast<Constant>(Amount); 1210 if (!C) 1211 return false; 1212 1213 // X shift by undef -> poison because it may shift by the bitwidth. 1214 if (Q.isUndefValue(C)) 1215 return true; 1216 1217 // Shifting by the bitwidth or more is undefined. 1218 if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) 1219 if (CI->getValue().uge(CI->getType()->getScalarSizeInBits())) 1220 return true; 1221 1222 // If all lanes of a vector shift are undefined the whole shift is. 1223 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) { 1224 for (unsigned I = 0, 1225 E = cast<FixedVectorType>(C->getType())->getNumElements(); 1226 I != E; ++I) 1227 if (!isPoisonShift(C->getAggregateElement(I), Q)) 1228 return false; 1229 return true; 1230 } 1231 1232 return false; 1233 } 1234 1235 /// Given operands for an Shl, LShr or AShr, see if we can fold the result. 1236 /// If not, this returns null. 1237 static Value *SimplifyShift(Instruction::BinaryOps Opcode, Value *Op0, 1238 Value *Op1, bool IsNSW, const SimplifyQuery &Q, 1239 unsigned MaxRecurse) { 1240 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1241 return C; 1242 1243 // 0 shift by X -> 0 1244 if (match(Op0, m_Zero())) 1245 return Constant::getNullValue(Op0->getType()); 1246 1247 // X shift by 0 -> X 1248 // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones 1249 // would be poison. 1250 Value *X; 1251 if (match(Op1, m_Zero()) || 1252 (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) 1253 return Op0; 1254 1255 // Fold undefined shifts. 1256 if (isPoisonShift(Op1, Q)) 1257 return PoisonValue::get(Op0->getType()); 1258 1259 // If the operation is with the result of a select instruction, check whether 1260 // operating on either branch of the select always yields the same value. 1261 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1262 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1263 return V; 1264 1265 // If the operation is with the result of a phi instruction, check whether 1266 // operating on all incoming values of the phi always yields the same value. 1267 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1268 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1269 return V; 1270 1271 // If any bits in the shift amount make that value greater than or equal to 1272 // the number of bits in the type, the shift is undefined. 1273 KnownBits KnownAmt = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1274 if (KnownAmt.getMinValue().uge(KnownAmt.getBitWidth())) 1275 return PoisonValue::get(Op0->getType()); 1276 1277 // If all valid bits in the shift amount are known zero, the first operand is 1278 // unchanged. 1279 unsigned NumValidShiftBits = Log2_32_Ceil(KnownAmt.getBitWidth()); 1280 if (KnownAmt.countMinTrailingZeros() >= NumValidShiftBits) 1281 return Op0; 1282 1283 // Check for nsw shl leading to a poison value. 1284 if (IsNSW) { 1285 assert(Opcode == Instruction::Shl && "Expected shl for nsw instruction"); 1286 KnownBits KnownVal = computeKnownBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1287 KnownBits KnownShl = KnownBits::shl(KnownVal, KnownAmt); 1288 1289 if (KnownVal.Zero.isSignBitSet()) 1290 KnownShl.Zero.setSignBit(); 1291 if (KnownVal.One.isSignBitSet()) 1292 KnownShl.One.setSignBit(); 1293 1294 if (KnownShl.hasConflict()) 1295 return PoisonValue::get(Op0->getType()); 1296 } 1297 1298 return nullptr; 1299 } 1300 1301 /// Given operands for an Shl, LShr or AShr, see if we can 1302 /// fold the result. If not, this returns null. 1303 static Value *SimplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0, 1304 Value *Op1, bool isExact, const SimplifyQuery &Q, 1305 unsigned MaxRecurse) { 1306 if (Value *V = 1307 SimplifyShift(Opcode, Op0, Op1, /*IsNSW*/ false, Q, MaxRecurse)) 1308 return V; 1309 1310 // X >> X -> 0 1311 if (Op0 == Op1) 1312 return Constant::getNullValue(Op0->getType()); 1313 1314 // undef >> X -> 0 1315 // undef >> X -> undef (if it's exact) 1316 if (Q.isUndefValue(Op0)) 1317 return isExact ? Op0 : Constant::getNullValue(Op0->getType()); 1318 1319 // The low bit cannot be shifted out of an exact shift if it is set. 1320 if (isExact) { 1321 KnownBits Op0Known = computeKnownBits(Op0, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT); 1322 if (Op0Known.One[0]) 1323 return Op0; 1324 } 1325 1326 return nullptr; 1327 } 1328 1329 /// Given operands for an Shl, see if we can fold the result. 1330 /// If not, this returns null. 1331 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1332 const SimplifyQuery &Q, unsigned MaxRecurse) { 1333 if (Value *V = 1334 SimplifyShift(Instruction::Shl, Op0, Op1, isNSW, Q, MaxRecurse)) 1335 return V; 1336 1337 // undef << X -> 0 1338 // undef << X -> undef if (if it's NSW/NUW) 1339 if (Q.isUndefValue(Op0)) 1340 return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType()); 1341 1342 // (X >> A) << A -> X 1343 Value *X; 1344 if (Q.IIQ.UseInstrInfo && 1345 match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) 1346 return X; 1347 1348 // shl nuw i8 C, %x -> C iff C has sign bit set. 1349 if (isNUW && match(Op0, m_Negative())) 1350 return Op0; 1351 // NOTE: could use computeKnownBits() / LazyValueInfo, 1352 // but the cost-benefit analysis suggests it isn't worth it. 1353 1354 return nullptr; 1355 } 1356 1357 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1358 const SimplifyQuery &Q) { 1359 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit); 1360 } 1361 1362 /// Given operands for an LShr, see if we can fold the result. 1363 /// If not, this returns null. 1364 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1365 const SimplifyQuery &Q, unsigned MaxRecurse) { 1366 if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q, 1367 MaxRecurse)) 1368 return V; 1369 1370 // (X << A) >> A -> X 1371 Value *X; 1372 if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1)))) 1373 return X; 1374 1375 // ((X << A) | Y) >> A -> X if effective width of Y is not larger than A. 1376 // We can return X as we do in the above case since OR alters no bits in X. 1377 // SimplifyDemandedBits in InstCombine can do more general optimization for 1378 // bit manipulation. This pattern aims to provide opportunities for other 1379 // optimizers by supporting a simple but common case in InstSimplify. 1380 Value *Y; 1381 const APInt *ShRAmt, *ShLAmt; 1382 if (match(Op1, m_APInt(ShRAmt)) && 1383 match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) && 1384 *ShRAmt == *ShLAmt) { 1385 const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1386 const unsigned Width = Op0->getType()->getScalarSizeInBits(); 1387 const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros(); 1388 if (ShRAmt->uge(EffWidthY)) 1389 return X; 1390 } 1391 1392 return nullptr; 1393 } 1394 1395 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1396 const SimplifyQuery &Q) { 1397 return ::SimplifyLShrInst(Op0, Op1, isExact, Q, RecursionLimit); 1398 } 1399 1400 /// Given operands for an AShr, see if we can fold the result. 1401 /// If not, this returns null. 1402 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1403 const SimplifyQuery &Q, unsigned MaxRecurse) { 1404 if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q, 1405 MaxRecurse)) 1406 return V; 1407 1408 // all ones >>a X -> -1 1409 // Do not return Op0 because it may contain undef elements if it's a vector. 1410 if (match(Op0, m_AllOnes())) 1411 return Constant::getAllOnesValue(Op0->getType()); 1412 1413 // (X << A) >> A -> X 1414 Value *X; 1415 if (Q.IIQ.UseInstrInfo && match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1)))) 1416 return X; 1417 1418 // Arithmetic shifting an all-sign-bit value is a no-op. 1419 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1420 if (NumSignBits == Op0->getType()->getScalarSizeInBits()) 1421 return Op0; 1422 1423 return nullptr; 1424 } 1425 1426 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1427 const SimplifyQuery &Q) { 1428 return ::SimplifyAShrInst(Op0, Op1, isExact, Q, RecursionLimit); 1429 } 1430 1431 /// Commuted variants are assumed to be handled by calling this function again 1432 /// with the parameters swapped. 1433 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp, 1434 ICmpInst *UnsignedICmp, bool IsAnd, 1435 const SimplifyQuery &Q) { 1436 Value *X, *Y; 1437 1438 ICmpInst::Predicate EqPred; 1439 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) || 1440 !ICmpInst::isEquality(EqPred)) 1441 return nullptr; 1442 1443 ICmpInst::Predicate UnsignedPred; 1444 1445 Value *A, *B; 1446 // Y = (A - B); 1447 if (match(Y, m_Sub(m_Value(A), m_Value(B)))) { 1448 if (match(UnsignedICmp, 1449 m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) && 1450 ICmpInst::isUnsigned(UnsignedPred)) { 1451 // A >=/<= B || (A - B) != 0 <--> true 1452 if ((UnsignedPred == ICmpInst::ICMP_UGE || 1453 UnsignedPred == ICmpInst::ICMP_ULE) && 1454 EqPred == ICmpInst::ICMP_NE && !IsAnd) 1455 return ConstantInt::getTrue(UnsignedICmp->getType()); 1456 // A </> B && (A - B) == 0 <--> false 1457 if ((UnsignedPred == ICmpInst::ICMP_ULT || 1458 UnsignedPred == ICmpInst::ICMP_UGT) && 1459 EqPred == ICmpInst::ICMP_EQ && IsAnd) 1460 return ConstantInt::getFalse(UnsignedICmp->getType()); 1461 1462 // A </> B && (A - B) != 0 <--> A </> B 1463 // A </> B || (A - B) != 0 <--> (A - B) != 0 1464 if (EqPred == ICmpInst::ICMP_NE && (UnsignedPred == ICmpInst::ICMP_ULT || 1465 UnsignedPred == ICmpInst::ICMP_UGT)) 1466 return IsAnd ? UnsignedICmp : ZeroICmp; 1467 1468 // A <=/>= B && (A - B) == 0 <--> (A - B) == 0 1469 // A <=/>= B || (A - B) == 0 <--> A <=/>= B 1470 if (EqPred == ICmpInst::ICMP_EQ && (UnsignedPred == ICmpInst::ICMP_ULE || 1471 UnsignedPred == ICmpInst::ICMP_UGE)) 1472 return IsAnd ? ZeroICmp : UnsignedICmp; 1473 } 1474 1475 // Given Y = (A - B) 1476 // Y >= A && Y != 0 --> Y >= A iff B != 0 1477 // Y < A || Y == 0 --> Y < A iff B != 0 1478 if (match(UnsignedICmp, 1479 m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) { 1480 if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd && 1481 EqPred == ICmpInst::ICMP_NE && 1482 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1483 return UnsignedICmp; 1484 if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd && 1485 EqPred == ICmpInst::ICMP_EQ && 1486 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1487 return UnsignedICmp; 1488 } 1489 } 1490 1491 if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) && 1492 ICmpInst::isUnsigned(UnsignedPred)) 1493 ; 1494 else if (match(UnsignedICmp, 1495 m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) && 1496 ICmpInst::isUnsigned(UnsignedPred)) 1497 UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); 1498 else 1499 return nullptr; 1500 1501 // X > Y && Y == 0 --> Y == 0 iff X != 0 1502 // X > Y || Y == 0 --> X > Y iff X != 0 1503 if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ && 1504 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1505 return IsAnd ? ZeroICmp : UnsignedICmp; 1506 1507 // X <= Y && Y != 0 --> X <= Y iff X != 0 1508 // X <= Y || Y != 0 --> Y != 0 iff X != 0 1509 if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE && 1510 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1511 return IsAnd ? UnsignedICmp : ZeroICmp; 1512 1513 // The transforms below here are expected to be handled more generally with 1514 // simplifyAndOrOfICmpsWithLimitConst() or in InstCombine's 1515 // foldAndOrOfICmpsWithConstEq(). If we are looking to trim optimizer overlap, 1516 // these are candidates for removal. 1517 1518 // X < Y && Y != 0 --> X < Y 1519 // X < Y || Y != 0 --> Y != 0 1520 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE) 1521 return IsAnd ? UnsignedICmp : ZeroICmp; 1522 1523 // X >= Y && Y == 0 --> Y == 0 1524 // X >= Y || Y == 0 --> X >= Y 1525 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ) 1526 return IsAnd ? ZeroICmp : UnsignedICmp; 1527 1528 // X < Y && Y == 0 --> false 1529 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ && 1530 IsAnd) 1531 return getFalse(UnsignedICmp->getType()); 1532 1533 // X >= Y || Y != 0 --> true 1534 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE && 1535 !IsAnd) 1536 return getTrue(UnsignedICmp->getType()); 1537 1538 return nullptr; 1539 } 1540 1541 /// Commuted variants are assumed to be handled by calling this function again 1542 /// with the parameters swapped. 1543 static Value *simplifyAndOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) { 1544 ICmpInst::Predicate Pred0, Pred1; 1545 Value *A ,*B; 1546 if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) || 1547 !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B)))) 1548 return nullptr; 1549 1550 // We have (icmp Pred0, A, B) & (icmp Pred1, A, B). 1551 // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we 1552 // can eliminate Op1 from this 'and'. 1553 if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1)) 1554 return Op0; 1555 1556 // Check for any combination of predicates that are guaranteed to be disjoint. 1557 if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) || 1558 (Pred0 == ICmpInst::ICMP_EQ && ICmpInst::isFalseWhenEqual(Pred1)) || 1559 (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT) || 1560 (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)) 1561 return getFalse(Op0->getType()); 1562 1563 return nullptr; 1564 } 1565 1566 /// Commuted variants are assumed to be handled by calling this function again 1567 /// with the parameters swapped. 1568 static Value *simplifyOrOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) { 1569 ICmpInst::Predicate Pred0, Pred1; 1570 Value *A ,*B; 1571 if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) || 1572 !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B)))) 1573 return nullptr; 1574 1575 // We have (icmp Pred0, A, B) | (icmp Pred1, A, B). 1576 // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we 1577 // can eliminate Op0 from this 'or'. 1578 if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1)) 1579 return Op1; 1580 1581 // Check for any combination of predicates that cover the entire range of 1582 // possibilities. 1583 if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) || 1584 (Pred0 == ICmpInst::ICMP_NE && ICmpInst::isTrueWhenEqual(Pred1)) || 1585 (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGE) || 1586 (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE)) 1587 return getTrue(Op0->getType()); 1588 1589 return nullptr; 1590 } 1591 1592 /// Test if a pair of compares with a shared operand and 2 constants has an 1593 /// empty set intersection, full set union, or if one compare is a superset of 1594 /// the other. 1595 static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1, 1596 bool IsAnd) { 1597 // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)). 1598 if (Cmp0->getOperand(0) != Cmp1->getOperand(0)) 1599 return nullptr; 1600 1601 const APInt *C0, *C1; 1602 if (!match(Cmp0->getOperand(1), m_APInt(C0)) || 1603 !match(Cmp1->getOperand(1), m_APInt(C1))) 1604 return nullptr; 1605 1606 auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0); 1607 auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1); 1608 1609 // For and-of-compares, check if the intersection is empty: 1610 // (icmp X, C0) && (icmp X, C1) --> empty set --> false 1611 if (IsAnd && Range0.intersectWith(Range1).isEmptySet()) 1612 return getFalse(Cmp0->getType()); 1613 1614 // For or-of-compares, check if the union is full: 1615 // (icmp X, C0) || (icmp X, C1) --> full set --> true 1616 if (!IsAnd && Range0.unionWith(Range1).isFullSet()) 1617 return getTrue(Cmp0->getType()); 1618 1619 // Is one range a superset of the other? 1620 // If this is and-of-compares, take the smaller set: 1621 // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42 1622 // If this is or-of-compares, take the larger set: 1623 // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4 1624 if (Range0.contains(Range1)) 1625 return IsAnd ? Cmp1 : Cmp0; 1626 if (Range1.contains(Range0)) 1627 return IsAnd ? Cmp0 : Cmp1; 1628 1629 return nullptr; 1630 } 1631 1632 static Value *simplifyAndOrOfICmpsWithZero(ICmpInst *Cmp0, ICmpInst *Cmp1, 1633 bool IsAnd) { 1634 ICmpInst::Predicate P0 = Cmp0->getPredicate(), P1 = Cmp1->getPredicate(); 1635 if (!match(Cmp0->getOperand(1), m_Zero()) || 1636 !match(Cmp1->getOperand(1), m_Zero()) || P0 != P1) 1637 return nullptr; 1638 1639 if ((IsAnd && P0 != ICmpInst::ICMP_NE) || (!IsAnd && P1 != ICmpInst::ICMP_EQ)) 1640 return nullptr; 1641 1642 // We have either "(X == 0 || Y == 0)" or "(X != 0 && Y != 0)". 1643 Value *X = Cmp0->getOperand(0); 1644 Value *Y = Cmp1->getOperand(0); 1645 1646 // If one of the compares is a masked version of a (not) null check, then 1647 // that compare implies the other, so we eliminate the other. Optionally, look 1648 // through a pointer-to-int cast to match a null check of a pointer type. 1649 1650 // (X == 0) || (([ptrtoint] X & ?) == 0) --> ([ptrtoint] X & ?) == 0 1651 // (X == 0) || ((? & [ptrtoint] X) == 0) --> (? & [ptrtoint] X) == 0 1652 // (X != 0) && (([ptrtoint] X & ?) != 0) --> ([ptrtoint] X & ?) != 0 1653 // (X != 0) && ((? & [ptrtoint] X) != 0) --> (? & [ptrtoint] X) != 0 1654 if (match(Y, m_c_And(m_Specific(X), m_Value())) || 1655 match(Y, m_c_And(m_PtrToInt(m_Specific(X)), m_Value()))) 1656 return Cmp1; 1657 1658 // (([ptrtoint] Y & ?) == 0) || (Y == 0) --> ([ptrtoint] Y & ?) == 0 1659 // ((? & [ptrtoint] Y) == 0) || (Y == 0) --> (? & [ptrtoint] Y) == 0 1660 // (([ptrtoint] Y & ?) != 0) && (Y != 0) --> ([ptrtoint] Y & ?) != 0 1661 // ((? & [ptrtoint] Y) != 0) && (Y != 0) --> (? & [ptrtoint] Y) != 0 1662 if (match(X, m_c_And(m_Specific(Y), m_Value())) || 1663 match(X, m_c_And(m_PtrToInt(m_Specific(Y)), m_Value()))) 1664 return Cmp0; 1665 1666 return nullptr; 1667 } 1668 1669 static Value *simplifyAndOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1670 const InstrInfoQuery &IIQ) { 1671 // (icmp (add V, C0), C1) & (icmp V, C0) 1672 ICmpInst::Predicate Pred0, Pred1; 1673 const APInt *C0, *C1; 1674 Value *V; 1675 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1676 return nullptr; 1677 1678 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1679 return nullptr; 1680 1681 auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0)); 1682 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1683 return nullptr; 1684 1685 Type *ITy = Op0->getType(); 1686 bool isNSW = IIQ.hasNoSignedWrap(AddInst); 1687 bool isNUW = IIQ.hasNoUnsignedWrap(AddInst); 1688 1689 const APInt Delta = *C1 - *C0; 1690 if (C0->isStrictlyPositive()) { 1691 if (Delta == 2) { 1692 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT) 1693 return getFalse(ITy); 1694 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW) 1695 return getFalse(ITy); 1696 } 1697 if (Delta == 1) { 1698 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT) 1699 return getFalse(ITy); 1700 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW) 1701 return getFalse(ITy); 1702 } 1703 } 1704 if (C0->getBoolValue() && isNUW) { 1705 if (Delta == 2) 1706 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT) 1707 return getFalse(ITy); 1708 if (Delta == 1) 1709 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT) 1710 return getFalse(ITy); 1711 } 1712 1713 return nullptr; 1714 } 1715 1716 /// Try to eliminate compares with signed or unsigned min/max constants. 1717 static Value *simplifyAndOrOfICmpsWithLimitConst(ICmpInst *Cmp0, ICmpInst *Cmp1, 1718 bool IsAnd) { 1719 // Canonicalize an equality compare as Cmp0. 1720 if (Cmp1->isEquality()) 1721 std::swap(Cmp0, Cmp1); 1722 if (!Cmp0->isEquality()) 1723 return nullptr; 1724 1725 // The non-equality compare must include a common operand (X). Canonicalize 1726 // the common operand as operand 0 (the predicate is swapped if the common 1727 // operand was operand 1). 1728 ICmpInst::Predicate Pred0 = Cmp0->getPredicate(); 1729 Value *X = Cmp0->getOperand(0); 1730 ICmpInst::Predicate Pred1; 1731 bool HasNotOp = match(Cmp1, m_c_ICmp(Pred1, m_Not(m_Specific(X)), m_Value())); 1732 if (!HasNotOp && !match(Cmp1, m_c_ICmp(Pred1, m_Specific(X), m_Value()))) 1733 return nullptr; 1734 if (ICmpInst::isEquality(Pred1)) 1735 return nullptr; 1736 1737 // The equality compare must be against a constant. Flip bits if we matched 1738 // a bitwise not. Convert a null pointer constant to an integer zero value. 1739 APInt MinMaxC; 1740 const APInt *C; 1741 if (match(Cmp0->getOperand(1), m_APInt(C))) 1742 MinMaxC = HasNotOp ? ~*C : *C; 1743 else if (isa<ConstantPointerNull>(Cmp0->getOperand(1))) 1744 MinMaxC = APInt::getNullValue(8); 1745 else 1746 return nullptr; 1747 1748 // DeMorganize if this is 'or': P0 || P1 --> !P0 && !P1. 1749 if (!IsAnd) { 1750 Pred0 = ICmpInst::getInversePredicate(Pred0); 1751 Pred1 = ICmpInst::getInversePredicate(Pred1); 1752 } 1753 1754 // Normalize to unsigned compare and unsigned min/max value. 1755 // Example for 8-bit: -128 + 128 -> 0; 127 + 128 -> 255 1756 if (ICmpInst::isSigned(Pred1)) { 1757 Pred1 = ICmpInst::getUnsignedPredicate(Pred1); 1758 MinMaxC += APInt::getSignedMinValue(MinMaxC.getBitWidth()); 1759 } 1760 1761 // (X != MAX) && (X < Y) --> X < Y 1762 // (X == MAX) || (X >= Y) --> X >= Y 1763 if (MinMaxC.isMaxValue()) 1764 if (Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_ULT) 1765 return Cmp1; 1766 1767 // (X != MIN) && (X > Y) --> X > Y 1768 // (X == MIN) || (X <= Y) --> X <= Y 1769 if (MinMaxC.isMinValue()) 1770 if (Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_UGT) 1771 return Cmp1; 1772 1773 return nullptr; 1774 } 1775 1776 static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1777 const SimplifyQuery &Q) { 1778 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true, Q)) 1779 return X; 1780 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true, Q)) 1781 return X; 1782 1783 if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1)) 1784 return X; 1785 if (Value *X = simplifyAndOfICmpsWithSameOperands(Op1, Op0)) 1786 return X; 1787 1788 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true)) 1789 return X; 1790 1791 if (Value *X = simplifyAndOrOfICmpsWithLimitConst(Op0, Op1, true)) 1792 return X; 1793 1794 if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, true)) 1795 return X; 1796 1797 if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1798 return X; 1799 if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1800 return X; 1801 1802 return nullptr; 1803 } 1804 1805 static Value *simplifyOrOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1806 const InstrInfoQuery &IIQ) { 1807 // (icmp (add V, C0), C1) | (icmp V, C0) 1808 ICmpInst::Predicate Pred0, Pred1; 1809 const APInt *C0, *C1; 1810 Value *V; 1811 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1812 return nullptr; 1813 1814 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1815 return nullptr; 1816 1817 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0)); 1818 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1819 return nullptr; 1820 1821 Type *ITy = Op0->getType(); 1822 bool isNSW = IIQ.hasNoSignedWrap(AddInst); 1823 bool isNUW = IIQ.hasNoUnsignedWrap(AddInst); 1824 1825 const APInt Delta = *C1 - *C0; 1826 if (C0->isStrictlyPositive()) { 1827 if (Delta == 2) { 1828 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE) 1829 return getTrue(ITy); 1830 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW) 1831 return getTrue(ITy); 1832 } 1833 if (Delta == 1) { 1834 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE) 1835 return getTrue(ITy); 1836 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW) 1837 return getTrue(ITy); 1838 } 1839 } 1840 if (C0->getBoolValue() && isNUW) { 1841 if (Delta == 2) 1842 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE) 1843 return getTrue(ITy); 1844 if (Delta == 1) 1845 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE) 1846 return getTrue(ITy); 1847 } 1848 1849 return nullptr; 1850 } 1851 1852 static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1853 const SimplifyQuery &Q) { 1854 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false, Q)) 1855 return X; 1856 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false, Q)) 1857 return X; 1858 1859 if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1)) 1860 return X; 1861 if (Value *X = simplifyOrOfICmpsWithSameOperands(Op1, Op0)) 1862 return X; 1863 1864 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false)) 1865 return X; 1866 1867 if (Value *X = simplifyAndOrOfICmpsWithLimitConst(Op0, Op1, false)) 1868 return X; 1869 1870 if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, false)) 1871 return X; 1872 1873 if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1874 return X; 1875 if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1876 return X; 1877 1878 return nullptr; 1879 } 1880 1881 static Value *simplifyAndOrOfFCmps(const TargetLibraryInfo *TLI, 1882 FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) { 1883 Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); 1884 Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); 1885 if (LHS0->getType() != RHS0->getType()) 1886 return nullptr; 1887 1888 FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); 1889 if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) || 1890 (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) { 1891 // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y 1892 // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X 1893 // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y 1894 // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X 1895 // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y 1896 // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X 1897 // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y 1898 // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X 1899 if ((isKnownNeverNaN(LHS0, TLI) && (LHS1 == RHS0 || LHS1 == RHS1)) || 1900 (isKnownNeverNaN(LHS1, TLI) && (LHS0 == RHS0 || LHS0 == RHS1))) 1901 return RHS; 1902 1903 // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y 1904 // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X 1905 // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y 1906 // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X 1907 // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y 1908 // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X 1909 // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y 1910 // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X 1911 if ((isKnownNeverNaN(RHS0, TLI) && (RHS1 == LHS0 || RHS1 == LHS1)) || 1912 (isKnownNeverNaN(RHS1, TLI) && (RHS0 == LHS0 || RHS0 == LHS1))) 1913 return LHS; 1914 } 1915 1916 return nullptr; 1917 } 1918 1919 static Value *simplifyAndOrOfCmps(const SimplifyQuery &Q, 1920 Value *Op0, Value *Op1, bool IsAnd) { 1921 // Look through casts of the 'and' operands to find compares. 1922 auto *Cast0 = dyn_cast<CastInst>(Op0); 1923 auto *Cast1 = dyn_cast<CastInst>(Op1); 1924 if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() && 1925 Cast0->getSrcTy() == Cast1->getSrcTy()) { 1926 Op0 = Cast0->getOperand(0); 1927 Op1 = Cast1->getOperand(0); 1928 } 1929 1930 Value *V = nullptr; 1931 auto *ICmp0 = dyn_cast<ICmpInst>(Op0); 1932 auto *ICmp1 = dyn_cast<ICmpInst>(Op1); 1933 if (ICmp0 && ICmp1) 1934 V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q) 1935 : simplifyOrOfICmps(ICmp0, ICmp1, Q); 1936 1937 auto *FCmp0 = dyn_cast<FCmpInst>(Op0); 1938 auto *FCmp1 = dyn_cast<FCmpInst>(Op1); 1939 if (FCmp0 && FCmp1) 1940 V = simplifyAndOrOfFCmps(Q.TLI, FCmp0, FCmp1, IsAnd); 1941 1942 if (!V) 1943 return nullptr; 1944 if (!Cast0) 1945 return V; 1946 1947 // If we looked through casts, we can only handle a constant simplification 1948 // because we are not allowed to create a cast instruction here. 1949 if (auto *C = dyn_cast<Constant>(V)) 1950 return ConstantExpr::getCast(Cast0->getOpcode(), C, Cast0->getType()); 1951 1952 return nullptr; 1953 } 1954 1955 /// Given a bitwise logic op, check if the operands are add/sub with a common 1956 /// source value and inverted constant (identity: C - X -> ~(X + ~C)). 1957 static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1, 1958 Instruction::BinaryOps Opcode) { 1959 assert(Op0->getType() == Op1->getType() && "Mismatched binop types"); 1960 assert(BinaryOperator::isBitwiseLogicOp(Opcode) && "Expected logic op"); 1961 Value *X; 1962 Constant *C1, *C2; 1963 if ((match(Op0, m_Add(m_Value(X), m_Constant(C1))) && 1964 match(Op1, m_Sub(m_Constant(C2), m_Specific(X)))) || 1965 (match(Op1, m_Add(m_Value(X), m_Constant(C1))) && 1966 match(Op0, m_Sub(m_Constant(C2), m_Specific(X))))) { 1967 if (ConstantExpr::getNot(C1) == C2) { 1968 // (X + C) & (~C - X) --> (X + C) & ~(X + C) --> 0 1969 // (X + C) | (~C - X) --> (X + C) | ~(X + C) --> -1 1970 // (X + C) ^ (~C - X) --> (X + C) ^ ~(X + C) --> -1 1971 Type *Ty = Op0->getType(); 1972 return Opcode == Instruction::And ? ConstantInt::getNullValue(Ty) 1973 : ConstantInt::getAllOnesValue(Ty); 1974 } 1975 } 1976 return nullptr; 1977 } 1978 1979 /// Given operands for an And, see if we can fold the result. 1980 /// If not, this returns null. 1981 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1982 unsigned MaxRecurse) { 1983 if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q)) 1984 return C; 1985 1986 // X & undef -> 0 1987 if (Q.isUndefValue(Op1)) 1988 return Constant::getNullValue(Op0->getType()); 1989 1990 // X & X = X 1991 if (Op0 == Op1) 1992 return Op0; 1993 1994 // X & 0 = 0 1995 if (match(Op1, m_Zero())) 1996 return Constant::getNullValue(Op0->getType()); 1997 1998 // X & -1 = X 1999 if (match(Op1, m_AllOnes())) 2000 return Op0; 2001 2002 // A & ~A = ~A & A = 0 2003 if (match(Op0, m_Not(m_Specific(Op1))) || 2004 match(Op1, m_Not(m_Specific(Op0)))) 2005 return Constant::getNullValue(Op0->getType()); 2006 2007 // (A | ?) & A = A 2008 if (match(Op0, m_c_Or(m_Specific(Op1), m_Value()))) 2009 return Op1; 2010 2011 // A & (A | ?) = A 2012 if (match(Op1, m_c_Or(m_Specific(Op0), m_Value()))) 2013 return Op0; 2014 2015 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And)) 2016 return V; 2017 2018 // A mask that only clears known zeros of a shifted value is a no-op. 2019 Value *X; 2020 const APInt *Mask; 2021 const APInt *ShAmt; 2022 if (match(Op1, m_APInt(Mask))) { 2023 // If all bits in the inverted and shifted mask are clear: 2024 // and (shl X, ShAmt), Mask --> shl X, ShAmt 2025 if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) && 2026 (~(*Mask)).lshr(*ShAmt).isNullValue()) 2027 return Op0; 2028 2029 // If all bits in the inverted and shifted mask are clear: 2030 // and (lshr X, ShAmt), Mask --> lshr X, ShAmt 2031 if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) && 2032 (~(*Mask)).shl(*ShAmt).isNullValue()) 2033 return Op0; 2034 } 2035 2036 // If we have a multiplication overflow check that is being 'and'ed with a 2037 // check that one of the multipliers is not zero, we can omit the 'and', and 2038 // only keep the overflow check. 2039 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, true)) 2040 return Op1; 2041 if (isCheckForZeroAndMulWithOverflow(Op1, Op0, true)) 2042 return Op0; 2043 2044 // A & (-A) = A if A is a power of two or zero. 2045 if (match(Op0, m_Neg(m_Specific(Op1))) || 2046 match(Op1, m_Neg(m_Specific(Op0)))) { 2047 if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, 2048 Q.DT)) 2049 return Op0; 2050 if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, 2051 Q.DT)) 2052 return Op1; 2053 } 2054 2055 // This is a similar pattern used for checking if a value is a power-of-2: 2056 // (A - 1) & A --> 0 (if A is a power-of-2 or 0) 2057 // A & (A - 1) --> 0 (if A is a power-of-2 or 0) 2058 if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) && 2059 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2060 return Constant::getNullValue(Op1->getType()); 2061 if (match(Op1, m_Add(m_Specific(Op0), m_AllOnes())) && 2062 isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2063 return Constant::getNullValue(Op0->getType()); 2064 2065 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true)) 2066 return V; 2067 2068 // Try some generic simplifications for associative operations. 2069 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, 2070 MaxRecurse)) 2071 return V; 2072 2073 // And distributes over Or. Try some generic simplifications based on this. 2074 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2075 Instruction::Or, Q, MaxRecurse)) 2076 return V; 2077 2078 // And distributes over Xor. Try some generic simplifications based on this. 2079 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2080 Instruction::Xor, Q, MaxRecurse)) 2081 return V; 2082 2083 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2084 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2085 // A & (A && B) -> A && B 2086 if (match(Op1, m_Select(m_Specific(Op0), m_Value(), m_Zero()))) 2087 return Op1; 2088 else if (match(Op0, m_Select(m_Specific(Op1), m_Value(), m_Zero()))) 2089 return Op0; 2090 } 2091 // If the operation is with the result of a select instruction, check 2092 // whether operating on either branch of the select always yields the same 2093 // value. 2094 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q, 2095 MaxRecurse)) 2096 return V; 2097 } 2098 2099 // If the operation is with the result of a phi instruction, check whether 2100 // operating on all incoming values of the phi always yields the same value. 2101 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2102 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q, 2103 MaxRecurse)) 2104 return V; 2105 2106 // Assuming the effective width of Y is not larger than A, i.e. all bits 2107 // from X and Y are disjoint in (X << A) | Y, 2108 // if the mask of this AND op covers all bits of X or Y, while it covers 2109 // no bits from the other, we can bypass this AND op. E.g., 2110 // ((X << A) | Y) & Mask -> Y, 2111 // if Mask = ((1 << effective_width_of(Y)) - 1) 2112 // ((X << A) | Y) & Mask -> X << A, 2113 // if Mask = ((1 << effective_width_of(X)) - 1) << A 2114 // SimplifyDemandedBits in InstCombine can optimize the general case. 2115 // This pattern aims to help other passes for a common case. 2116 Value *Y, *XShifted; 2117 if (match(Op1, m_APInt(Mask)) && 2118 match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)), 2119 m_Value(XShifted)), 2120 m_Value(Y)))) { 2121 const unsigned Width = Op0->getType()->getScalarSizeInBits(); 2122 const unsigned ShftCnt = ShAmt->getLimitedValue(Width); 2123 const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2124 const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros(); 2125 if (EffWidthY <= ShftCnt) { 2126 const KnownBits XKnown = computeKnownBits(X, Q.DL, 0, Q.AC, Q.CxtI, 2127 Q.DT); 2128 const unsigned EffWidthX = Width - XKnown.countMinLeadingZeros(); 2129 const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY); 2130 const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt; 2131 // If the mask is extracting all bits from X or Y as is, we can skip 2132 // this AND op. 2133 if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask)) 2134 return Y; 2135 if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask)) 2136 return XShifted; 2137 } 2138 } 2139 2140 return nullptr; 2141 } 2142 2143 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2144 return ::SimplifyAndInst(Op0, Op1, Q, RecursionLimit); 2145 } 2146 2147 /// Given operands for an Or, see if we can fold the result. 2148 /// If not, this returns null. 2149 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2150 unsigned MaxRecurse) { 2151 if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q)) 2152 return C; 2153 2154 // X | undef -> -1 2155 // X | -1 = -1 2156 // Do not return Op1 because it may contain undef elements if it's a vector. 2157 if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes())) 2158 return Constant::getAllOnesValue(Op0->getType()); 2159 2160 // X | X = X 2161 // X | 0 = X 2162 if (Op0 == Op1 || match(Op1, m_Zero())) 2163 return Op0; 2164 2165 // A | ~A = ~A | A = -1 2166 if (match(Op0, m_Not(m_Specific(Op1))) || 2167 match(Op1, m_Not(m_Specific(Op0)))) 2168 return Constant::getAllOnesValue(Op0->getType()); 2169 2170 // (A & ?) | A = A 2171 if (match(Op0, m_c_And(m_Specific(Op1), m_Value()))) 2172 return Op1; 2173 2174 // A | (A & ?) = A 2175 if (match(Op1, m_c_And(m_Specific(Op0), m_Value()))) 2176 return Op0; 2177 2178 // ~(A & ?) | A = -1 2179 if (match(Op0, m_Not(m_c_And(m_Specific(Op1), m_Value())))) 2180 return Constant::getAllOnesValue(Op1->getType()); 2181 2182 // A | ~(A & ?) = -1 2183 if (match(Op1, m_Not(m_c_And(m_Specific(Op0), m_Value())))) 2184 return Constant::getAllOnesValue(Op0->getType()); 2185 2186 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Or)) 2187 return V; 2188 2189 Value *A, *B, *NotA; 2190 // (A & ~B) | (A ^ B) -> (A ^ B) 2191 // (~B & A) | (A ^ B) -> (A ^ B) 2192 // (A & ~B) | (B ^ A) -> (B ^ A) 2193 // (~B & A) | (B ^ A) -> (B ^ A) 2194 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && 2195 (match(Op0, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) || 2196 match(Op0, m_c_And(m_Not(m_Specific(A)), m_Specific(B))))) 2197 return Op1; 2198 2199 // Commute the 'or' operands. 2200 // (A ^ B) | (A & ~B) -> (A ^ B) 2201 // (A ^ B) | (~B & A) -> (A ^ B) 2202 // (B ^ A) | (A & ~B) -> (B ^ A) 2203 // (B ^ A) | (~B & A) -> (B ^ A) 2204 if (match(Op0, m_Xor(m_Value(A), m_Value(B))) && 2205 (match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) || 2206 match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B))))) 2207 return Op0; 2208 2209 // (A & B) | (~A ^ B) -> (~A ^ B) 2210 // (B & A) | (~A ^ B) -> (~A ^ B) 2211 // (A & B) | (B ^ ~A) -> (B ^ ~A) 2212 // (B & A) | (B ^ ~A) -> (B ^ ~A) 2213 if (match(Op0, m_And(m_Value(A), m_Value(B))) && 2214 (match(Op1, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) || 2215 match(Op1, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B))))) 2216 return Op1; 2217 2218 // Commute the 'or' operands. 2219 // (~A ^ B) | (A & B) -> (~A ^ B) 2220 // (~A ^ B) | (B & A) -> (~A ^ B) 2221 // (B ^ ~A) | (A & B) -> (B ^ ~A) 2222 // (B ^ ~A) | (B & A) -> (B ^ ~A) 2223 if (match(Op1, m_And(m_Value(A), m_Value(B))) && 2224 (match(Op0, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) || 2225 match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B))))) 2226 return Op0; 2227 2228 // (~A & B) | ~(A | B) --> ~A 2229 // (~A & B) | ~(B | A) --> ~A 2230 // (B & ~A) | ~(A | B) --> ~A 2231 // (B & ~A) | ~(B | A) --> ~A 2232 if (match(Op0, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))), 2233 m_Value(B))) && 2234 match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) 2235 return NotA; 2236 2237 // Commute the 'or' operands. 2238 // ~(A | B) | (~A & B) --> ~A 2239 // ~(B | A) | (~A & B) --> ~A 2240 // ~(A | B) | (B & ~A) --> ~A 2241 // ~(B | A) | (B & ~A) --> ~A 2242 if (match(Op1, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))), 2243 m_Value(B))) && 2244 match(Op0, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) 2245 return NotA; 2246 2247 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false)) 2248 return V; 2249 2250 // If we have a multiplication overflow check that is being 'and'ed with a 2251 // check that one of the multipliers is not zero, we can omit the 'and', and 2252 // only keep the overflow check. 2253 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, false)) 2254 return Op1; 2255 if (isCheckForZeroAndMulWithOverflow(Op1, Op0, false)) 2256 return Op0; 2257 2258 // Try some generic simplifications for associative operations. 2259 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, 2260 MaxRecurse)) 2261 return V; 2262 2263 // Or distributes over And. Try some generic simplifications based on this. 2264 if (Value *V = expandCommutativeBinOp(Instruction::Or, Op0, Op1, 2265 Instruction::And, Q, MaxRecurse)) 2266 return V; 2267 2268 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2269 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2270 // A | (A || B) -> A || B 2271 if (match(Op1, m_Select(m_Specific(Op0), m_One(), m_Value()))) 2272 return Op1; 2273 else if (match(Op0, m_Select(m_Specific(Op1), m_One(), m_Value()))) 2274 return Op0; 2275 } 2276 // If the operation is with the result of a select instruction, check 2277 // whether operating on either branch of the select always yields the same 2278 // value. 2279 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, 2280 MaxRecurse)) 2281 return V; 2282 } 2283 2284 // (A & C1)|(B & C2) 2285 const APInt *C1, *C2; 2286 if (match(Op0, m_And(m_Value(A), m_APInt(C1))) && 2287 match(Op1, m_And(m_Value(B), m_APInt(C2)))) { 2288 if (*C1 == ~*C2) { 2289 // (A & C1)|(B & C2) 2290 // If we have: ((V + N) & C1) | (V & C2) 2291 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 2292 // replace with V+N. 2293 Value *N; 2294 if (C2->isMask() && // C2 == 0+1+ 2295 match(A, m_c_Add(m_Specific(B), m_Value(N)))) { 2296 // Add commutes, try both ways. 2297 if (MaskedValueIsZero(N, *C2, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2298 return A; 2299 } 2300 // Or commutes, try both ways. 2301 if (C1->isMask() && 2302 match(B, m_c_Add(m_Specific(A), m_Value(N)))) { 2303 // Add commutes, try both ways. 2304 if (MaskedValueIsZero(N, *C1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2305 return B; 2306 } 2307 } 2308 } 2309 2310 // If the operation is with the result of a phi instruction, check whether 2311 // operating on all incoming values of the phi always yields the same value. 2312 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2313 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2314 return V; 2315 2316 return nullptr; 2317 } 2318 2319 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2320 return ::SimplifyOrInst(Op0, Op1, Q, RecursionLimit); 2321 } 2322 2323 /// Given operands for a Xor, see if we can fold the result. 2324 /// If not, this returns null. 2325 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2326 unsigned MaxRecurse) { 2327 if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q)) 2328 return C; 2329 2330 // A ^ undef -> undef 2331 if (Q.isUndefValue(Op1)) 2332 return Op1; 2333 2334 // A ^ 0 = A 2335 if (match(Op1, m_Zero())) 2336 return Op0; 2337 2338 // A ^ A = 0 2339 if (Op0 == Op1) 2340 return Constant::getNullValue(Op0->getType()); 2341 2342 // A ^ ~A = ~A ^ A = -1 2343 if (match(Op0, m_Not(m_Specific(Op1))) || 2344 match(Op1, m_Not(m_Specific(Op0)))) 2345 return Constant::getAllOnesValue(Op0->getType()); 2346 2347 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor)) 2348 return V; 2349 2350 // Try some generic simplifications for associative operations. 2351 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, 2352 MaxRecurse)) 2353 return V; 2354 2355 // Threading Xor over selects and phi nodes is pointless, so don't bother. 2356 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 2357 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 2358 // only if B and C are equal. If B and C are equal then (since we assume 2359 // that operands have already been simplified) "select(cond, B, C)" should 2360 // have been simplified to the common value of B and C already. Analysing 2361 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 2362 // for threading over phi nodes. 2363 2364 return nullptr; 2365 } 2366 2367 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2368 return ::SimplifyXorInst(Op0, Op1, Q, RecursionLimit); 2369 } 2370 2371 2372 static Type *GetCompareTy(Value *Op) { 2373 return CmpInst::makeCmpResultType(Op->getType()); 2374 } 2375 2376 /// Rummage around inside V looking for something equivalent to the comparison 2377 /// "LHS Pred RHS". Return such a value if found, otherwise return null. 2378 /// Helper function for analyzing max/min idioms. 2379 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 2380 Value *LHS, Value *RHS) { 2381 SelectInst *SI = dyn_cast<SelectInst>(V); 2382 if (!SI) 2383 return nullptr; 2384 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 2385 if (!Cmp) 2386 return nullptr; 2387 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 2388 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 2389 return Cmp; 2390 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 2391 LHS == CmpRHS && RHS == CmpLHS) 2392 return Cmp; 2393 return nullptr; 2394 } 2395 2396 // A significant optimization not implemented here is assuming that alloca 2397 // addresses are not equal to incoming argument values. They don't *alias*, 2398 // as we say, but that doesn't mean they aren't equal, so we take a 2399 // conservative approach. 2400 // 2401 // This is inspired in part by C++11 5.10p1: 2402 // "Two pointers of the same type compare equal if and only if they are both 2403 // null, both point to the same function, or both represent the same 2404 // address." 2405 // 2406 // This is pretty permissive. 2407 // 2408 // It's also partly due to C11 6.5.9p6: 2409 // "Two pointers compare equal if and only if both are null pointers, both are 2410 // pointers to the same object (including a pointer to an object and a 2411 // subobject at its beginning) or function, both are pointers to one past the 2412 // last element of the same array object, or one is a pointer to one past the 2413 // end of one array object and the other is a pointer to the start of a 2414 // different array object that happens to immediately follow the first array 2415 // object in the address space.) 2416 // 2417 // C11's version is more restrictive, however there's no reason why an argument 2418 // couldn't be a one-past-the-end value for a stack object in the caller and be 2419 // equal to the beginning of a stack object in the callee. 2420 // 2421 // If the C and C++ standards are ever made sufficiently restrictive in this 2422 // area, it may be possible to update LLVM's semantics accordingly and reinstate 2423 // this optimization. 2424 static Constant * 2425 computePointerICmp(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 2426 const SimplifyQuery &Q) { 2427 const DataLayout &DL = Q.DL; 2428 const TargetLibraryInfo *TLI = Q.TLI; 2429 const DominatorTree *DT = Q.DT; 2430 const Instruction *CxtI = Q.CxtI; 2431 const InstrInfoQuery &IIQ = Q.IIQ; 2432 2433 // First, skip past any trivial no-ops. 2434 LHS = LHS->stripPointerCasts(); 2435 RHS = RHS->stripPointerCasts(); 2436 2437 // A non-null pointer is not equal to a null pointer. 2438 if (isa<ConstantPointerNull>(RHS) && ICmpInst::isEquality(Pred) && 2439 llvm::isKnownNonZero(LHS, DL, 0, nullptr, nullptr, nullptr, 2440 IIQ.UseInstrInfo)) 2441 return ConstantInt::get(GetCompareTy(LHS), 2442 !CmpInst::isTrueWhenEqual(Pred)); 2443 2444 // We can only fold certain predicates on pointer comparisons. 2445 switch (Pred) { 2446 default: 2447 return nullptr; 2448 2449 // Equality comaprisons are easy to fold. 2450 case CmpInst::ICMP_EQ: 2451 case CmpInst::ICMP_NE: 2452 break; 2453 2454 // We can only handle unsigned relational comparisons because 'inbounds' on 2455 // a GEP only protects against unsigned wrapping. 2456 case CmpInst::ICMP_UGT: 2457 case CmpInst::ICMP_UGE: 2458 case CmpInst::ICMP_ULT: 2459 case CmpInst::ICMP_ULE: 2460 // However, we have to switch them to their signed variants to handle 2461 // negative indices from the base pointer. 2462 Pred = ICmpInst::getSignedPredicate(Pred); 2463 break; 2464 } 2465 2466 // Strip off any constant offsets so that we can reason about them. 2467 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets 2468 // here and compare base addresses like AliasAnalysis does, however there are 2469 // numerous hazards. AliasAnalysis and its utilities rely on special rules 2470 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis 2471 // doesn't need to guarantee pointer inequality when it says NoAlias. 2472 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS); 2473 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS); 2474 2475 // If LHS and RHS are related via constant offsets to the same base 2476 // value, we can replace it with an icmp which just compares the offsets. 2477 if (LHS == RHS) 2478 return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset); 2479 2480 // Various optimizations for (in)equality comparisons. 2481 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) { 2482 // Different non-empty allocations that exist at the same time have 2483 // different addresses (if the program can tell). Global variables always 2484 // exist, so they always exist during the lifetime of each other and all 2485 // allocas. Two different allocas usually have different addresses... 2486 // 2487 // However, if there's an @llvm.stackrestore dynamically in between two 2488 // allocas, they may have the same address. It's tempting to reduce the 2489 // scope of the problem by only looking at *static* allocas here. That would 2490 // cover the majority of allocas while significantly reducing the likelihood 2491 // of having an @llvm.stackrestore pop up in the middle. However, it's not 2492 // actually impossible for an @llvm.stackrestore to pop up in the middle of 2493 // an entry block. Also, if we have a block that's not attached to a 2494 // function, we can't tell if it's "static" under the current definition. 2495 // Theoretically, this problem could be fixed by creating a new kind of 2496 // instruction kind specifically for static allocas. Such a new instruction 2497 // could be required to be at the top of the entry block, thus preventing it 2498 // from being subject to a @llvm.stackrestore. Instcombine could even 2499 // convert regular allocas into these special allocas. It'd be nifty. 2500 // However, until then, this problem remains open. 2501 // 2502 // So, we'll assume that two non-empty allocas have different addresses 2503 // for now. 2504 // 2505 // With all that, if the offsets are within the bounds of their allocations 2506 // (and not one-past-the-end! so we can't use inbounds!), and their 2507 // allocations aren't the same, the pointers are not equal. 2508 // 2509 // Note that it's not necessary to check for LHS being a global variable 2510 // address, due to canonicalization and constant folding. 2511 if (isa<AllocaInst>(LHS) && 2512 (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) { 2513 ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset); 2514 ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset); 2515 uint64_t LHSSize, RHSSize; 2516 ObjectSizeOpts Opts; 2517 Opts.NullIsUnknownSize = 2518 NullPointerIsDefined(cast<AllocaInst>(LHS)->getFunction()); 2519 if (LHSOffsetCI && RHSOffsetCI && 2520 getObjectSize(LHS, LHSSize, DL, TLI, Opts) && 2521 getObjectSize(RHS, RHSSize, DL, TLI, Opts)) { 2522 const APInt &LHSOffsetValue = LHSOffsetCI->getValue(); 2523 const APInt &RHSOffsetValue = RHSOffsetCI->getValue(); 2524 if (!LHSOffsetValue.isNegative() && 2525 !RHSOffsetValue.isNegative() && 2526 LHSOffsetValue.ult(LHSSize) && 2527 RHSOffsetValue.ult(RHSSize)) { 2528 return ConstantInt::get(GetCompareTy(LHS), 2529 !CmpInst::isTrueWhenEqual(Pred)); 2530 } 2531 } 2532 2533 // Repeat the above check but this time without depending on DataLayout 2534 // or being able to compute a precise size. 2535 if (!cast<PointerType>(LHS->getType())->isEmptyTy() && 2536 !cast<PointerType>(RHS->getType())->isEmptyTy() && 2537 LHSOffset->isNullValue() && 2538 RHSOffset->isNullValue()) 2539 return ConstantInt::get(GetCompareTy(LHS), 2540 !CmpInst::isTrueWhenEqual(Pred)); 2541 } 2542 2543 // Even if an non-inbounds GEP occurs along the path we can still optimize 2544 // equality comparisons concerning the result. We avoid walking the whole 2545 // chain again by starting where the last calls to 2546 // stripAndComputeConstantOffsets left off and accumulate the offsets. 2547 Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true); 2548 Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true); 2549 if (LHS == RHS) 2550 return ConstantExpr::getICmp(Pred, 2551 ConstantExpr::getAdd(LHSOffset, LHSNoBound), 2552 ConstantExpr::getAdd(RHSOffset, RHSNoBound)); 2553 2554 // If one side of the equality comparison must come from a noalias call 2555 // (meaning a system memory allocation function), and the other side must 2556 // come from a pointer that cannot overlap with dynamically-allocated 2557 // memory within the lifetime of the current function (allocas, byval 2558 // arguments, globals), then determine the comparison result here. 2559 SmallVector<const Value *, 8> LHSUObjs, RHSUObjs; 2560 getUnderlyingObjects(LHS, LHSUObjs); 2561 getUnderlyingObjects(RHS, RHSUObjs); 2562 2563 // Is the set of underlying objects all noalias calls? 2564 auto IsNAC = [](ArrayRef<const Value *> Objects) { 2565 return all_of(Objects, isNoAliasCall); 2566 }; 2567 2568 // Is the set of underlying objects all things which must be disjoint from 2569 // noalias calls. For allocas, we consider only static ones (dynamic 2570 // allocas might be transformed into calls to malloc not simultaneously 2571 // live with the compared-to allocation). For globals, we exclude symbols 2572 // that might be resolve lazily to symbols in another dynamically-loaded 2573 // library (and, thus, could be malloc'ed by the implementation). 2574 auto IsAllocDisjoint = [](ArrayRef<const Value *> Objects) { 2575 return all_of(Objects, [](const Value *V) { 2576 if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) 2577 return AI->getParent() && AI->getFunction() && AI->isStaticAlloca(); 2578 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) 2579 return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() || 2580 GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) && 2581 !GV->isThreadLocal(); 2582 if (const Argument *A = dyn_cast<Argument>(V)) 2583 return A->hasByValAttr(); 2584 return false; 2585 }); 2586 }; 2587 2588 if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) || 2589 (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs))) 2590 return ConstantInt::get(GetCompareTy(LHS), 2591 !CmpInst::isTrueWhenEqual(Pred)); 2592 2593 // Fold comparisons for non-escaping pointer even if the allocation call 2594 // cannot be elided. We cannot fold malloc comparison to null. Also, the 2595 // dynamic allocation call could be either of the operands. 2596 Value *MI = nullptr; 2597 if (isAllocLikeFn(LHS, TLI) && 2598 llvm::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT)) 2599 MI = LHS; 2600 else if (isAllocLikeFn(RHS, TLI) && 2601 llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT)) 2602 MI = RHS; 2603 // FIXME: We should also fold the compare when the pointer escapes, but the 2604 // compare dominates the pointer escape 2605 if (MI && !PointerMayBeCaptured(MI, true, true)) 2606 return ConstantInt::get(GetCompareTy(LHS), 2607 CmpInst::isFalseWhenEqual(Pred)); 2608 } 2609 2610 // Otherwise, fail. 2611 return nullptr; 2612 } 2613 2614 /// Fold an icmp when its operands have i1 scalar type. 2615 static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS, 2616 Value *RHS, const SimplifyQuery &Q) { 2617 Type *ITy = GetCompareTy(LHS); // The return type. 2618 Type *OpTy = LHS->getType(); // The operand type. 2619 if (!OpTy->isIntOrIntVectorTy(1)) 2620 return nullptr; 2621 2622 // A boolean compared to true/false can be simplified in 14 out of the 20 2623 // (10 predicates * 2 constants) possible combinations. Cases not handled here 2624 // require a 'not' of the LHS, so those must be transformed in InstCombine. 2625 if (match(RHS, m_Zero())) { 2626 switch (Pred) { 2627 case CmpInst::ICMP_NE: // X != 0 -> X 2628 case CmpInst::ICMP_UGT: // X >u 0 -> X 2629 case CmpInst::ICMP_SLT: // X <s 0 -> X 2630 return LHS; 2631 2632 case CmpInst::ICMP_ULT: // X <u 0 -> false 2633 case CmpInst::ICMP_SGT: // X >s 0 -> false 2634 return getFalse(ITy); 2635 2636 case CmpInst::ICMP_UGE: // X >=u 0 -> true 2637 case CmpInst::ICMP_SLE: // X <=s 0 -> true 2638 return getTrue(ITy); 2639 2640 default: break; 2641 } 2642 } else if (match(RHS, m_One())) { 2643 switch (Pred) { 2644 case CmpInst::ICMP_EQ: // X == 1 -> X 2645 case CmpInst::ICMP_UGE: // X >=u 1 -> X 2646 case CmpInst::ICMP_SLE: // X <=s -1 -> X 2647 return LHS; 2648 2649 case CmpInst::ICMP_UGT: // X >u 1 -> false 2650 case CmpInst::ICMP_SLT: // X <s -1 -> false 2651 return getFalse(ITy); 2652 2653 case CmpInst::ICMP_ULE: // X <=u 1 -> true 2654 case CmpInst::ICMP_SGE: // X >=s -1 -> true 2655 return getTrue(ITy); 2656 2657 default: break; 2658 } 2659 } 2660 2661 switch (Pred) { 2662 default: 2663 break; 2664 case ICmpInst::ICMP_UGE: 2665 if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false)) 2666 return getTrue(ITy); 2667 break; 2668 case ICmpInst::ICMP_SGE: 2669 /// For signed comparison, the values for an i1 are 0 and -1 2670 /// respectively. This maps into a truth table of: 2671 /// LHS | RHS | LHS >=s RHS | LHS implies RHS 2672 /// 0 | 0 | 1 (0 >= 0) | 1 2673 /// 0 | 1 | 1 (0 >= -1) | 1 2674 /// 1 | 0 | 0 (-1 >= 0) | 0 2675 /// 1 | 1 | 1 (-1 >= -1) | 1 2676 if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false)) 2677 return getTrue(ITy); 2678 break; 2679 case ICmpInst::ICMP_ULE: 2680 if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false)) 2681 return getTrue(ITy); 2682 break; 2683 } 2684 2685 return nullptr; 2686 } 2687 2688 /// Try hard to fold icmp with zero RHS because this is a common case. 2689 static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS, 2690 Value *RHS, const SimplifyQuery &Q) { 2691 if (!match(RHS, m_Zero())) 2692 return nullptr; 2693 2694 Type *ITy = GetCompareTy(LHS); // The return type. 2695 switch (Pred) { 2696 default: 2697 llvm_unreachable("Unknown ICmp predicate!"); 2698 case ICmpInst::ICMP_ULT: 2699 return getFalse(ITy); 2700 case ICmpInst::ICMP_UGE: 2701 return getTrue(ITy); 2702 case ICmpInst::ICMP_EQ: 2703 case ICmpInst::ICMP_ULE: 2704 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2705 return getFalse(ITy); 2706 break; 2707 case ICmpInst::ICMP_NE: 2708 case ICmpInst::ICMP_UGT: 2709 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2710 return getTrue(ITy); 2711 break; 2712 case ICmpInst::ICMP_SLT: { 2713 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2714 if (LHSKnown.isNegative()) 2715 return getTrue(ITy); 2716 if (LHSKnown.isNonNegative()) 2717 return getFalse(ITy); 2718 break; 2719 } 2720 case ICmpInst::ICMP_SLE: { 2721 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2722 if (LHSKnown.isNegative()) 2723 return getTrue(ITy); 2724 if (LHSKnown.isNonNegative() && 2725 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2726 return getFalse(ITy); 2727 break; 2728 } 2729 case ICmpInst::ICMP_SGE: { 2730 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2731 if (LHSKnown.isNegative()) 2732 return getFalse(ITy); 2733 if (LHSKnown.isNonNegative()) 2734 return getTrue(ITy); 2735 break; 2736 } 2737 case ICmpInst::ICMP_SGT: { 2738 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2739 if (LHSKnown.isNegative()) 2740 return getFalse(ITy); 2741 if (LHSKnown.isNonNegative() && 2742 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2743 return getTrue(ITy); 2744 break; 2745 } 2746 } 2747 2748 return nullptr; 2749 } 2750 2751 static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS, 2752 Value *RHS, const InstrInfoQuery &IIQ) { 2753 Type *ITy = GetCompareTy(RHS); // The return type. 2754 2755 Value *X; 2756 // Sign-bit checks can be optimized to true/false after unsigned 2757 // floating-point casts: 2758 // icmp slt (bitcast (uitofp X)), 0 --> false 2759 // icmp sgt (bitcast (uitofp X)), -1 --> true 2760 if (match(LHS, m_BitCast(m_UIToFP(m_Value(X))))) { 2761 if (Pred == ICmpInst::ICMP_SLT && match(RHS, m_Zero())) 2762 return ConstantInt::getFalse(ITy); 2763 if (Pred == ICmpInst::ICMP_SGT && match(RHS, m_AllOnes())) 2764 return ConstantInt::getTrue(ITy); 2765 } 2766 2767 const APInt *C; 2768 if (!match(RHS, m_APIntAllowUndef(C))) 2769 return nullptr; 2770 2771 // Rule out tautological comparisons (eg., ult 0 or uge 0). 2772 ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C); 2773 if (RHS_CR.isEmptySet()) 2774 return ConstantInt::getFalse(ITy); 2775 if (RHS_CR.isFullSet()) 2776 return ConstantInt::getTrue(ITy); 2777 2778 ConstantRange LHS_CR = computeConstantRange(LHS, IIQ.UseInstrInfo); 2779 if (!LHS_CR.isFullSet()) { 2780 if (RHS_CR.contains(LHS_CR)) 2781 return ConstantInt::getTrue(ITy); 2782 if (RHS_CR.inverse().contains(LHS_CR)) 2783 return ConstantInt::getFalse(ITy); 2784 } 2785 2786 // (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC) 2787 // (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC) 2788 const APInt *MulC; 2789 if (ICmpInst::isEquality(Pred) && 2790 ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowUndef(MulC))) && 2791 *MulC != 0 && C->urem(*MulC) != 0) || 2792 (match(LHS, m_NSWMul(m_Value(), m_APIntAllowUndef(MulC))) && 2793 *MulC != 0 && C->srem(*MulC) != 0))) 2794 return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE); 2795 2796 return nullptr; 2797 } 2798 2799 static Value *simplifyICmpWithBinOpOnLHS( 2800 CmpInst::Predicate Pred, BinaryOperator *LBO, Value *RHS, 2801 const SimplifyQuery &Q, unsigned MaxRecurse) { 2802 Type *ITy = GetCompareTy(RHS); // The return type. 2803 2804 Value *Y = nullptr; 2805 // icmp pred (or X, Y), X 2806 if (match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) { 2807 if (Pred == ICmpInst::ICMP_ULT) 2808 return getFalse(ITy); 2809 if (Pred == ICmpInst::ICMP_UGE) 2810 return getTrue(ITy); 2811 2812 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) { 2813 KnownBits RHSKnown = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2814 KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2815 if (RHSKnown.isNonNegative() && YKnown.isNegative()) 2816 return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy); 2817 if (RHSKnown.isNegative() || YKnown.isNonNegative()) 2818 return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy); 2819 } 2820 } 2821 2822 // icmp pred (and X, Y), X 2823 if (match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) { 2824 if (Pred == ICmpInst::ICMP_UGT) 2825 return getFalse(ITy); 2826 if (Pred == ICmpInst::ICMP_ULE) 2827 return getTrue(ITy); 2828 } 2829 2830 // icmp pred (urem X, Y), Y 2831 if (match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 2832 switch (Pred) { 2833 default: 2834 break; 2835 case ICmpInst::ICMP_SGT: 2836 case ICmpInst::ICMP_SGE: { 2837 KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2838 if (!Known.isNonNegative()) 2839 break; 2840 LLVM_FALLTHROUGH; 2841 } 2842 case ICmpInst::ICMP_EQ: 2843 case ICmpInst::ICMP_UGT: 2844 case ICmpInst::ICMP_UGE: 2845 return getFalse(ITy); 2846 case ICmpInst::ICMP_SLT: 2847 case ICmpInst::ICMP_SLE: { 2848 KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2849 if (!Known.isNonNegative()) 2850 break; 2851 LLVM_FALLTHROUGH; 2852 } 2853 case ICmpInst::ICMP_NE: 2854 case ICmpInst::ICMP_ULT: 2855 case ICmpInst::ICMP_ULE: 2856 return getTrue(ITy); 2857 } 2858 } 2859 2860 // icmp pred (urem X, Y), X 2861 if (match(LBO, m_URem(m_Specific(RHS), m_Value()))) { 2862 if (Pred == ICmpInst::ICMP_ULE) 2863 return getTrue(ITy); 2864 if (Pred == ICmpInst::ICMP_UGT) 2865 return getFalse(ITy); 2866 } 2867 2868 // x >> y <=u x 2869 // x udiv y <=u x. 2870 if (match(LBO, m_LShr(m_Specific(RHS), m_Value())) || 2871 match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) { 2872 // icmp pred (X op Y), X 2873 if (Pred == ICmpInst::ICMP_UGT) 2874 return getFalse(ITy); 2875 if (Pred == ICmpInst::ICMP_ULE) 2876 return getTrue(ITy); 2877 } 2878 2879 // (x*C1)/C2 <= x for C1 <= C2. 2880 // This holds even if the multiplication overflows: Assume that x != 0 and 2881 // arithmetic is modulo M. For overflow to occur we must have C1 >= M/x and 2882 // thus C2 >= M/x. It follows that (x*C1)/C2 <= (M-1)/C2 <= ((M-1)*x)/M < x. 2883 // 2884 // Additionally, either the multiplication and division might be represented 2885 // as shifts: 2886 // (x*C1)>>C2 <= x for C1 < 2**C2. 2887 // (x<<C1)/C2 <= x for 2**C1 < C2. 2888 const APInt *C1, *C2; 2889 if ((match(LBO, m_UDiv(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 2890 C1->ule(*C2)) || 2891 (match(LBO, m_LShr(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 2892 C1->ule(APInt(C2->getBitWidth(), 1) << *C2)) || 2893 (match(LBO, m_UDiv(m_Shl(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 2894 (APInt(C1->getBitWidth(), 1) << *C1).ule(*C2))) { 2895 if (Pred == ICmpInst::ICMP_UGT) 2896 return getFalse(ITy); 2897 if (Pred == ICmpInst::ICMP_ULE) 2898 return getTrue(ITy); 2899 } 2900 2901 return nullptr; 2902 } 2903 2904 2905 // If only one of the icmp's operands has NSW flags, try to prove that: 2906 // 2907 // icmp slt (x + C1), (x +nsw C2) 2908 // 2909 // is equivalent to: 2910 // 2911 // icmp slt C1, C2 2912 // 2913 // which is true if x + C2 has the NSW flags set and: 2914 // *) C1 < C2 && C1 >= 0, or 2915 // *) C2 < C1 && C1 <= 0. 2916 // 2917 static bool trySimplifyICmpWithAdds(CmpInst::Predicate Pred, Value *LHS, 2918 Value *RHS) { 2919 // TODO: only support icmp slt for now. 2920 if (Pred != CmpInst::ICMP_SLT) 2921 return false; 2922 2923 // Canonicalize nsw add as RHS. 2924 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 2925 std::swap(LHS, RHS); 2926 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 2927 return false; 2928 2929 Value *X; 2930 const APInt *C1, *C2; 2931 if (!match(LHS, m_c_Add(m_Value(X), m_APInt(C1))) || 2932 !match(RHS, m_c_Add(m_Specific(X), m_APInt(C2)))) 2933 return false; 2934 2935 return (C1->slt(*C2) && C1->isNonNegative()) || 2936 (C2->slt(*C1) && C1->isNonPositive()); 2937 } 2938 2939 2940 /// TODO: A large part of this logic is duplicated in InstCombine's 2941 /// foldICmpBinOp(). We should be able to share that and avoid the code 2942 /// duplication. 2943 static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS, 2944 Value *RHS, const SimplifyQuery &Q, 2945 unsigned MaxRecurse) { 2946 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 2947 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 2948 if (MaxRecurse && (LBO || RBO)) { 2949 // Analyze the case when either LHS or RHS is an add instruction. 2950 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr; 2951 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 2952 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 2953 if (LBO && LBO->getOpcode() == Instruction::Add) { 2954 A = LBO->getOperand(0); 2955 B = LBO->getOperand(1); 2956 NoLHSWrapProblem = 2957 ICmpInst::isEquality(Pred) || 2958 (CmpInst::isUnsigned(Pred) && 2959 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) || 2960 (CmpInst::isSigned(Pred) && 2961 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO))); 2962 } 2963 if (RBO && RBO->getOpcode() == Instruction::Add) { 2964 C = RBO->getOperand(0); 2965 D = RBO->getOperand(1); 2966 NoRHSWrapProblem = 2967 ICmpInst::isEquality(Pred) || 2968 (CmpInst::isUnsigned(Pred) && 2969 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) || 2970 (CmpInst::isSigned(Pred) && 2971 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO))); 2972 } 2973 2974 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 2975 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 2976 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A, 2977 Constant::getNullValue(RHS->getType()), Q, 2978 MaxRecurse - 1)) 2979 return V; 2980 2981 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 2982 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 2983 if (Value *V = 2984 SimplifyICmpInst(Pred, Constant::getNullValue(LHS->getType()), 2985 C == LHS ? D : C, Q, MaxRecurse - 1)) 2986 return V; 2987 2988 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 2989 bool CanSimplify = (NoLHSWrapProblem && NoRHSWrapProblem) || 2990 trySimplifyICmpWithAdds(Pred, LHS, RHS); 2991 if (A && C && (A == C || A == D || B == C || B == D) && CanSimplify) { 2992 // Determine Y and Z in the form icmp (X+Y), (X+Z). 2993 Value *Y, *Z; 2994 if (A == C) { 2995 // C + B == C + D -> B == D 2996 Y = B; 2997 Z = D; 2998 } else if (A == D) { 2999 // D + B == C + D -> B == C 3000 Y = B; 3001 Z = C; 3002 } else if (B == C) { 3003 // A + C == C + D -> A == D 3004 Y = A; 3005 Z = D; 3006 } else { 3007 assert(B == D); 3008 // A + D == C + D -> A == C 3009 Y = A; 3010 Z = C; 3011 } 3012 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1)) 3013 return V; 3014 } 3015 } 3016 3017 if (LBO) 3018 if (Value *V = simplifyICmpWithBinOpOnLHS(Pred, LBO, RHS, Q, MaxRecurse)) 3019 return V; 3020 3021 if (RBO) 3022 if (Value *V = simplifyICmpWithBinOpOnLHS( 3023 ICmpInst::getSwappedPredicate(Pred), RBO, LHS, Q, MaxRecurse)) 3024 return V; 3025 3026 // 0 - (zext X) pred C 3027 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) { 3028 const APInt *C; 3029 if (match(RHS, m_APInt(C))) { 3030 if (C->isStrictlyPositive()) { 3031 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_NE) 3032 return ConstantInt::getTrue(GetCompareTy(RHS)); 3033 if (Pred == ICmpInst::ICMP_SGE || Pred == ICmpInst::ICMP_EQ) 3034 return ConstantInt::getFalse(GetCompareTy(RHS)); 3035 } 3036 if (C->isNonNegative()) { 3037 if (Pred == ICmpInst::ICMP_SLE) 3038 return ConstantInt::getTrue(GetCompareTy(RHS)); 3039 if (Pred == ICmpInst::ICMP_SGT) 3040 return ConstantInt::getFalse(GetCompareTy(RHS)); 3041 } 3042 } 3043 } 3044 3045 // If C2 is a power-of-2 and C is not: 3046 // (C2 << X) == C --> false 3047 // (C2 << X) != C --> true 3048 const APInt *C; 3049 if (match(LHS, m_Shl(m_Power2(), m_Value())) && 3050 match(RHS, m_APIntAllowUndef(C)) && !C->isPowerOf2()) { 3051 // C2 << X can equal zero in some circumstances. 3052 // This simplification might be unsafe if C is zero. 3053 // 3054 // We know it is safe if: 3055 // - The shift is nsw. We can't shift out the one bit. 3056 // - The shift is nuw. We can't shift out the one bit. 3057 // - C2 is one. 3058 // - C isn't zero. 3059 if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3060 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3061 match(LHS, m_Shl(m_One(), m_Value())) || !C->isNullValue()) { 3062 if (Pred == ICmpInst::ICMP_EQ) 3063 return ConstantInt::getFalse(GetCompareTy(RHS)); 3064 if (Pred == ICmpInst::ICMP_NE) 3065 return ConstantInt::getTrue(GetCompareTy(RHS)); 3066 } 3067 } 3068 3069 // TODO: This is overly constrained. LHS can be any power-of-2. 3070 // (1 << X) >u 0x8000 --> false 3071 // (1 << X) <=u 0x8000 --> true 3072 if (match(LHS, m_Shl(m_One(), m_Value())) && match(RHS, m_SignMask())) { 3073 if (Pred == ICmpInst::ICMP_UGT) 3074 return ConstantInt::getFalse(GetCompareTy(RHS)); 3075 if (Pred == ICmpInst::ICMP_ULE) 3076 return ConstantInt::getTrue(GetCompareTy(RHS)); 3077 } 3078 3079 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() && 3080 LBO->getOperand(1) == RBO->getOperand(1)) { 3081 switch (LBO->getOpcode()) { 3082 default: 3083 break; 3084 case Instruction::UDiv: 3085 case Instruction::LShr: 3086 if (ICmpInst::isSigned(Pred) || !Q.IIQ.isExact(LBO) || 3087 !Q.IIQ.isExact(RBO)) 3088 break; 3089 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3090 RBO->getOperand(0), Q, MaxRecurse - 1)) 3091 return V; 3092 break; 3093 case Instruction::SDiv: 3094 if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) || 3095 !Q.IIQ.isExact(RBO)) 3096 break; 3097 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3098 RBO->getOperand(0), Q, MaxRecurse - 1)) 3099 return V; 3100 break; 3101 case Instruction::AShr: 3102 if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO)) 3103 break; 3104 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3105 RBO->getOperand(0), Q, MaxRecurse - 1)) 3106 return V; 3107 break; 3108 case Instruction::Shl: { 3109 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3110 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3111 if (!NUW && !NSW) 3112 break; 3113 if (!NSW && ICmpInst::isSigned(Pred)) 3114 break; 3115 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3116 RBO->getOperand(0), Q, MaxRecurse - 1)) 3117 return V; 3118 break; 3119 } 3120 } 3121 } 3122 return nullptr; 3123 } 3124 3125 /// Simplify integer comparisons where at least one operand of the compare 3126 /// matches an integer min/max idiom. 3127 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS, 3128 Value *RHS, const SimplifyQuery &Q, 3129 unsigned MaxRecurse) { 3130 Type *ITy = GetCompareTy(LHS); // The return type. 3131 Value *A, *B; 3132 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 3133 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 3134 3135 // Signed variants on "max(a,b)>=a -> true". 3136 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3137 if (A != RHS) 3138 std::swap(A, B); // smax(A, B) pred A. 3139 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3140 // We analyze this as smax(A, B) pred A. 3141 P = Pred; 3142 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 3143 (A == LHS || B == LHS)) { 3144 if (A != LHS) 3145 std::swap(A, B); // A pred smax(A, B). 3146 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3147 // We analyze this as smax(A, B) swapped-pred A. 3148 P = CmpInst::getSwappedPredicate(Pred); 3149 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 3150 (A == RHS || B == RHS)) { 3151 if (A != RHS) 3152 std::swap(A, B); // smin(A, B) pred A. 3153 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3154 // We analyze this as smax(-A, -B) swapped-pred -A. 3155 // Note that we do not need to actually form -A or -B thanks to EqP. 3156 P = CmpInst::getSwappedPredicate(Pred); 3157 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 3158 (A == LHS || B == LHS)) { 3159 if (A != LHS) 3160 std::swap(A, B); // A pred smin(A, B). 3161 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3162 // We analyze this as smax(-A, -B) pred -A. 3163 // Note that we do not need to actually form -A or -B thanks to EqP. 3164 P = Pred; 3165 } 3166 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3167 // Cases correspond to "max(A, B) p A". 3168 switch (P) { 3169 default: 3170 break; 3171 case CmpInst::ICMP_EQ: 3172 case CmpInst::ICMP_SLE: 3173 // Equivalent to "A EqP B". This may be the same as the condition tested 3174 // in the max/min; if so, we can just return that. 3175 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 3176 return V; 3177 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 3178 return V; 3179 // Otherwise, see if "A EqP B" simplifies. 3180 if (MaxRecurse) 3181 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3182 return V; 3183 break; 3184 case CmpInst::ICMP_NE: 3185 case CmpInst::ICMP_SGT: { 3186 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3187 // Equivalent to "A InvEqP B". This may be the same as the condition 3188 // tested in the max/min; if so, we can just return that. 3189 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 3190 return V; 3191 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 3192 return V; 3193 // Otherwise, see if "A InvEqP B" simplifies. 3194 if (MaxRecurse) 3195 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3196 return V; 3197 break; 3198 } 3199 case CmpInst::ICMP_SGE: 3200 // Always true. 3201 return getTrue(ITy); 3202 case CmpInst::ICMP_SLT: 3203 // Always false. 3204 return getFalse(ITy); 3205 } 3206 } 3207 3208 // Unsigned variants on "max(a,b)>=a -> true". 3209 P = CmpInst::BAD_ICMP_PREDICATE; 3210 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3211 if (A != RHS) 3212 std::swap(A, B); // umax(A, B) pred A. 3213 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3214 // We analyze this as umax(A, B) pred A. 3215 P = Pred; 3216 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 3217 (A == LHS || B == LHS)) { 3218 if (A != LHS) 3219 std::swap(A, B); // A pred umax(A, B). 3220 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3221 // We analyze this as umax(A, B) swapped-pred A. 3222 P = CmpInst::getSwappedPredicate(Pred); 3223 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 3224 (A == RHS || B == RHS)) { 3225 if (A != RHS) 3226 std::swap(A, B); // umin(A, B) pred A. 3227 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3228 // We analyze this as umax(-A, -B) swapped-pred -A. 3229 // Note that we do not need to actually form -A or -B thanks to EqP. 3230 P = CmpInst::getSwappedPredicate(Pred); 3231 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 3232 (A == LHS || B == LHS)) { 3233 if (A != LHS) 3234 std::swap(A, B); // A pred umin(A, B). 3235 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3236 // We analyze this as umax(-A, -B) pred -A. 3237 // Note that we do not need to actually form -A or -B thanks to EqP. 3238 P = Pred; 3239 } 3240 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3241 // Cases correspond to "max(A, B) p A". 3242 switch (P) { 3243 default: 3244 break; 3245 case CmpInst::ICMP_EQ: 3246 case CmpInst::ICMP_ULE: 3247 // Equivalent to "A EqP B". This may be the same as the condition tested 3248 // in the max/min; if so, we can just return that. 3249 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 3250 return V; 3251 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 3252 return V; 3253 // Otherwise, see if "A EqP B" simplifies. 3254 if (MaxRecurse) 3255 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3256 return V; 3257 break; 3258 case CmpInst::ICMP_NE: 3259 case CmpInst::ICMP_UGT: { 3260 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3261 // Equivalent to "A InvEqP B". This may be the same as the condition 3262 // tested in the max/min; if so, we can just return that. 3263 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 3264 return V; 3265 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 3266 return V; 3267 // Otherwise, see if "A InvEqP B" simplifies. 3268 if (MaxRecurse) 3269 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3270 return V; 3271 break; 3272 } 3273 case CmpInst::ICMP_UGE: 3274 return getTrue(ITy); 3275 case CmpInst::ICMP_ULT: 3276 return getFalse(ITy); 3277 } 3278 } 3279 3280 // Comparing 1 each of min/max with a common operand? 3281 // Canonicalize min operand to RHS. 3282 if (match(LHS, m_UMin(m_Value(), m_Value())) || 3283 match(LHS, m_SMin(m_Value(), m_Value()))) { 3284 std::swap(LHS, RHS); 3285 Pred = ICmpInst::getSwappedPredicate(Pred); 3286 } 3287 3288 Value *C, *D; 3289 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 3290 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 3291 (A == C || A == D || B == C || B == D)) { 3292 // smax(A, B) >=s smin(A, D) --> true 3293 if (Pred == CmpInst::ICMP_SGE) 3294 return getTrue(ITy); 3295 // smax(A, B) <s smin(A, D) --> false 3296 if (Pred == CmpInst::ICMP_SLT) 3297 return getFalse(ITy); 3298 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 3299 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 3300 (A == C || A == D || B == C || B == D)) { 3301 // umax(A, B) >=u umin(A, D) --> true 3302 if (Pred == CmpInst::ICMP_UGE) 3303 return getTrue(ITy); 3304 // umax(A, B) <u umin(A, D) --> false 3305 if (Pred == CmpInst::ICMP_ULT) 3306 return getFalse(ITy); 3307 } 3308 3309 return nullptr; 3310 } 3311 3312 static Value *simplifyICmpWithDominatingAssume(CmpInst::Predicate Predicate, 3313 Value *LHS, Value *RHS, 3314 const SimplifyQuery &Q) { 3315 // Gracefully handle instructions that have not been inserted yet. 3316 if (!Q.AC || !Q.CxtI || !Q.CxtI->getParent()) 3317 return nullptr; 3318 3319 for (Value *AssumeBaseOp : {LHS, RHS}) { 3320 for (auto &AssumeVH : Q.AC->assumptionsFor(AssumeBaseOp)) { 3321 if (!AssumeVH) 3322 continue; 3323 3324 CallInst *Assume = cast<CallInst>(AssumeVH); 3325 if (Optional<bool> Imp = 3326 isImpliedCondition(Assume->getArgOperand(0), Predicate, LHS, RHS, 3327 Q.DL)) 3328 if (isValidAssumeForContext(Assume, Q.CxtI, Q.DT)) 3329 return ConstantInt::get(GetCompareTy(LHS), *Imp); 3330 } 3331 } 3332 3333 return nullptr; 3334 } 3335 3336 /// Given operands for an ICmpInst, see if we can fold the result. 3337 /// If not, this returns null. 3338 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3339 const SimplifyQuery &Q, unsigned MaxRecurse) { 3340 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 3341 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 3342 3343 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 3344 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 3345 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); 3346 3347 // If we have a constant, make sure it is on the RHS. 3348 std::swap(LHS, RHS); 3349 Pred = CmpInst::getSwappedPredicate(Pred); 3350 } 3351 assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X"); 3352 3353 Type *ITy = GetCompareTy(LHS); // The return type. 3354 3355 // For EQ and NE, we can always pick a value for the undef to make the 3356 // predicate pass or fail, so we can return undef. 3357 // Matches behavior in llvm::ConstantFoldCompareInstruction. 3358 if (Q.isUndefValue(RHS) && ICmpInst::isEquality(Pred)) 3359 return UndefValue::get(ITy); 3360 3361 // icmp X, X -> true/false 3362 // icmp X, undef -> true/false because undef could be X. 3363 if (LHS == RHS || Q.isUndefValue(RHS)) 3364 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 3365 3366 if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q)) 3367 return V; 3368 3369 // TODO: Sink/common this with other potentially expensive calls that use 3370 // ValueTracking? See comment below for isKnownNonEqual(). 3371 if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q)) 3372 return V; 3373 3374 if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ)) 3375 return V; 3376 3377 // If both operands have range metadata, use the metadata 3378 // to simplify the comparison. 3379 if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) { 3380 auto RHS_Instr = cast<Instruction>(RHS); 3381 auto LHS_Instr = cast<Instruction>(LHS); 3382 3383 if (Q.IIQ.getMetadata(RHS_Instr, LLVMContext::MD_range) && 3384 Q.IIQ.getMetadata(LHS_Instr, LLVMContext::MD_range)) { 3385 auto RHS_CR = getConstantRangeFromMetadata( 3386 *RHS_Instr->getMetadata(LLVMContext::MD_range)); 3387 auto LHS_CR = getConstantRangeFromMetadata( 3388 *LHS_Instr->getMetadata(LLVMContext::MD_range)); 3389 3390 if (LHS_CR.icmp(Pred, RHS_CR)) 3391 return ConstantInt::getTrue(RHS->getContext()); 3392 3393 if (LHS_CR.icmp(CmpInst::getInversePredicate(Pred), RHS_CR)) 3394 return ConstantInt::getFalse(RHS->getContext()); 3395 } 3396 } 3397 3398 // Compare of cast, for example (zext X) != 0 -> X != 0 3399 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 3400 Instruction *LI = cast<CastInst>(LHS); 3401 Value *SrcOp = LI->getOperand(0); 3402 Type *SrcTy = SrcOp->getType(); 3403 Type *DstTy = LI->getType(); 3404 3405 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 3406 // if the integer type is the same size as the pointer type. 3407 if (MaxRecurse && isa<PtrToIntInst>(LI) && 3408 Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) { 3409 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 3410 // Transfer the cast to the constant. 3411 if (Value *V = SimplifyICmpInst(Pred, SrcOp, 3412 ConstantExpr::getIntToPtr(RHSC, SrcTy), 3413 Q, MaxRecurse-1)) 3414 return V; 3415 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 3416 if (RI->getOperand(0)->getType() == SrcTy) 3417 // Compare without the cast. 3418 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 3419 Q, MaxRecurse-1)) 3420 return V; 3421 } 3422 } 3423 3424 if (isa<ZExtInst>(LHS)) { 3425 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 3426 // same type. 3427 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3428 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3429 // Compare X and Y. Note that signed predicates become unsigned. 3430 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 3431 SrcOp, RI->getOperand(0), Q, 3432 MaxRecurse-1)) 3433 return V; 3434 } 3435 // Fold (zext X) ule (sext X), (zext X) sge (sext X) to true. 3436 else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3437 if (SrcOp == RI->getOperand(0)) { 3438 if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE) 3439 return ConstantInt::getTrue(ITy); 3440 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT) 3441 return ConstantInt::getFalse(ITy); 3442 } 3443 } 3444 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 3445 // too. If not, then try to deduce the result of the comparison. 3446 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 3447 // Compute the constant that would happen if we truncated to SrcTy then 3448 // reextended to DstTy. 3449 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 3450 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy); 3451 3452 // If the re-extended constant didn't change then this is effectively 3453 // also a case of comparing two zero-extended values. 3454 if (RExt == CI && MaxRecurse) 3455 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 3456 SrcOp, Trunc, Q, MaxRecurse-1)) 3457 return V; 3458 3459 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 3460 // there. Use this to work out the result of the comparison. 3461 if (RExt != CI) { 3462 switch (Pred) { 3463 default: llvm_unreachable("Unknown ICmp predicate!"); 3464 // LHS <u RHS. 3465 case ICmpInst::ICMP_EQ: 3466 case ICmpInst::ICMP_UGT: 3467 case ICmpInst::ICMP_UGE: 3468 return ConstantInt::getFalse(CI->getContext()); 3469 3470 case ICmpInst::ICMP_NE: 3471 case ICmpInst::ICMP_ULT: 3472 case ICmpInst::ICMP_ULE: 3473 return ConstantInt::getTrue(CI->getContext()); 3474 3475 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 3476 // is non-negative then LHS <s RHS. 3477 case ICmpInst::ICMP_SGT: 3478 case ICmpInst::ICMP_SGE: 3479 return CI->getValue().isNegative() ? 3480 ConstantInt::getTrue(CI->getContext()) : 3481 ConstantInt::getFalse(CI->getContext()); 3482 3483 case ICmpInst::ICMP_SLT: 3484 case ICmpInst::ICMP_SLE: 3485 return CI->getValue().isNegative() ? 3486 ConstantInt::getFalse(CI->getContext()) : 3487 ConstantInt::getTrue(CI->getContext()); 3488 } 3489 } 3490 } 3491 } 3492 3493 if (isa<SExtInst>(LHS)) { 3494 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 3495 // same type. 3496 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3497 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3498 // Compare X and Y. Note that the predicate does not change. 3499 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 3500 Q, MaxRecurse-1)) 3501 return V; 3502 } 3503 // Fold (sext X) uge (zext X), (sext X) sle (zext X) to true. 3504 else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3505 if (SrcOp == RI->getOperand(0)) { 3506 if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE) 3507 return ConstantInt::getTrue(ITy); 3508 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT) 3509 return ConstantInt::getFalse(ITy); 3510 } 3511 } 3512 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 3513 // too. If not, then try to deduce the result of the comparison. 3514 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 3515 // Compute the constant that would happen if we truncated to SrcTy then 3516 // reextended to DstTy. 3517 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 3518 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy); 3519 3520 // If the re-extended constant didn't change then this is effectively 3521 // also a case of comparing two sign-extended values. 3522 if (RExt == CI && MaxRecurse) 3523 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1)) 3524 return V; 3525 3526 // Otherwise the upper bits of LHS are all equal, while RHS has varying 3527 // bits there. Use this to work out the result of the comparison. 3528 if (RExt != CI) { 3529 switch (Pred) { 3530 default: llvm_unreachable("Unknown ICmp predicate!"); 3531 case ICmpInst::ICMP_EQ: 3532 return ConstantInt::getFalse(CI->getContext()); 3533 case ICmpInst::ICMP_NE: 3534 return ConstantInt::getTrue(CI->getContext()); 3535 3536 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 3537 // LHS >s RHS. 3538 case ICmpInst::ICMP_SGT: 3539 case ICmpInst::ICMP_SGE: 3540 return CI->getValue().isNegative() ? 3541 ConstantInt::getTrue(CI->getContext()) : 3542 ConstantInt::getFalse(CI->getContext()); 3543 case ICmpInst::ICMP_SLT: 3544 case ICmpInst::ICMP_SLE: 3545 return CI->getValue().isNegative() ? 3546 ConstantInt::getFalse(CI->getContext()) : 3547 ConstantInt::getTrue(CI->getContext()); 3548 3549 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 3550 // LHS >u RHS. 3551 case ICmpInst::ICMP_UGT: 3552 case ICmpInst::ICMP_UGE: 3553 // Comparison is true iff the LHS <s 0. 3554 if (MaxRecurse) 3555 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 3556 Constant::getNullValue(SrcTy), 3557 Q, MaxRecurse-1)) 3558 return V; 3559 break; 3560 case ICmpInst::ICMP_ULT: 3561 case ICmpInst::ICMP_ULE: 3562 // Comparison is true iff the LHS >=s 0. 3563 if (MaxRecurse) 3564 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 3565 Constant::getNullValue(SrcTy), 3566 Q, MaxRecurse-1)) 3567 return V; 3568 break; 3569 } 3570 } 3571 } 3572 } 3573 } 3574 3575 // icmp eq|ne X, Y -> false|true if X != Y 3576 // This is potentially expensive, and we have already computedKnownBits for 3577 // compares with 0 above here, so only try this for a non-zero compare. 3578 if (ICmpInst::isEquality(Pred) && !match(RHS, m_Zero()) && 3579 isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) { 3580 return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy); 3581 } 3582 3583 if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse)) 3584 return V; 3585 3586 if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse)) 3587 return V; 3588 3589 if (Value *V = simplifyICmpWithDominatingAssume(Pred, LHS, RHS, Q)) 3590 return V; 3591 3592 // Simplify comparisons of related pointers using a powerful, recursive 3593 // GEP-walk when we have target data available.. 3594 if (LHS->getType()->isPointerTy()) 3595 if (auto *C = computePointerICmp(Pred, LHS, RHS, Q)) 3596 return C; 3597 if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS)) 3598 if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS)) 3599 if (Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) == 3600 Q.DL.getTypeSizeInBits(CLHS->getType()) && 3601 Q.DL.getTypeSizeInBits(CRHS->getPointerOperandType()) == 3602 Q.DL.getTypeSizeInBits(CRHS->getType())) 3603 if (auto *C = computePointerICmp(Pred, CLHS->getPointerOperand(), 3604 CRHS->getPointerOperand(), Q)) 3605 return C; 3606 3607 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) { 3608 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) { 3609 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() && 3610 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() && 3611 (ICmpInst::isEquality(Pred) || 3612 (GLHS->isInBounds() && GRHS->isInBounds() && 3613 Pred == ICmpInst::getSignedPredicate(Pred)))) { 3614 // The bases are equal and the indices are constant. Build a constant 3615 // expression GEP with the same indices and a null base pointer to see 3616 // what constant folding can make out of it. 3617 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType()); 3618 SmallVector<Value *, 4> IndicesLHS(GLHS->indices()); 3619 Constant *NewLHS = ConstantExpr::getGetElementPtr( 3620 GLHS->getSourceElementType(), Null, IndicesLHS); 3621 3622 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end()); 3623 Constant *NewRHS = ConstantExpr::getGetElementPtr( 3624 GLHS->getSourceElementType(), Null, IndicesRHS); 3625 Constant *NewICmp = ConstantExpr::getICmp(Pred, NewLHS, NewRHS); 3626 return ConstantFoldConstant(NewICmp, Q.DL); 3627 } 3628 } 3629 } 3630 3631 // If the comparison is with the result of a select instruction, check whether 3632 // comparing with either branch of the select always yields the same value. 3633 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 3634 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 3635 return V; 3636 3637 // If the comparison is with the result of a phi instruction, check whether 3638 // doing the compare with each incoming phi value yields a common result. 3639 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 3640 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 3641 return V; 3642 3643 return nullptr; 3644 } 3645 3646 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3647 const SimplifyQuery &Q) { 3648 return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 3649 } 3650 3651 /// Given operands for an FCmpInst, see if we can fold the result. 3652 /// If not, this returns null. 3653 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3654 FastMathFlags FMF, const SimplifyQuery &Q, 3655 unsigned MaxRecurse) { 3656 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 3657 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 3658 3659 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 3660 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 3661 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); 3662 3663 // If we have a constant, make sure it is on the RHS. 3664 std::swap(LHS, RHS); 3665 Pred = CmpInst::getSwappedPredicate(Pred); 3666 } 3667 3668 // Fold trivial predicates. 3669 Type *RetTy = GetCompareTy(LHS); 3670 if (Pred == FCmpInst::FCMP_FALSE) 3671 return getFalse(RetTy); 3672 if (Pred == FCmpInst::FCMP_TRUE) 3673 return getTrue(RetTy); 3674 3675 // Fold (un)ordered comparison if we can determine there are no NaNs. 3676 if (Pred == FCmpInst::FCMP_UNO || Pred == FCmpInst::FCMP_ORD) 3677 if (FMF.noNaNs() || 3678 (isKnownNeverNaN(LHS, Q.TLI) && isKnownNeverNaN(RHS, Q.TLI))) 3679 return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD); 3680 3681 // NaN is unordered; NaN is not ordered. 3682 assert((FCmpInst::isOrdered(Pred) || FCmpInst::isUnordered(Pred)) && 3683 "Comparison must be either ordered or unordered"); 3684 if (match(RHS, m_NaN())) 3685 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 3686 3687 // fcmp pred x, undef and fcmp pred undef, x 3688 // fold to true if unordered, false if ordered 3689 if (Q.isUndefValue(LHS) || Q.isUndefValue(RHS)) { 3690 // Choosing NaN for the undef will always make unordered comparison succeed 3691 // and ordered comparison fail. 3692 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 3693 } 3694 3695 // fcmp x,x -> true/false. Not all compares are foldable. 3696 if (LHS == RHS) { 3697 if (CmpInst::isTrueWhenEqual(Pred)) 3698 return getTrue(RetTy); 3699 if (CmpInst::isFalseWhenEqual(Pred)) 3700 return getFalse(RetTy); 3701 } 3702 3703 // Handle fcmp with constant RHS. 3704 // TODO: Use match with a specific FP value, so these work with vectors with 3705 // undef lanes. 3706 const APFloat *C; 3707 if (match(RHS, m_APFloat(C))) { 3708 // Check whether the constant is an infinity. 3709 if (C->isInfinity()) { 3710 if (C->isNegative()) { 3711 switch (Pred) { 3712 case FCmpInst::FCMP_OLT: 3713 // No value is ordered and less than negative infinity. 3714 return getFalse(RetTy); 3715 case FCmpInst::FCMP_UGE: 3716 // All values are unordered with or at least negative infinity. 3717 return getTrue(RetTy); 3718 default: 3719 break; 3720 } 3721 } else { 3722 switch (Pred) { 3723 case FCmpInst::FCMP_OGT: 3724 // No value is ordered and greater than infinity. 3725 return getFalse(RetTy); 3726 case FCmpInst::FCMP_ULE: 3727 // All values are unordered with and at most infinity. 3728 return getTrue(RetTy); 3729 default: 3730 break; 3731 } 3732 } 3733 3734 // LHS == Inf 3735 if (Pred == FCmpInst::FCMP_OEQ && isKnownNeverInfinity(LHS, Q.TLI)) 3736 return getFalse(RetTy); 3737 // LHS != Inf 3738 if (Pred == FCmpInst::FCMP_UNE && isKnownNeverInfinity(LHS, Q.TLI)) 3739 return getTrue(RetTy); 3740 // LHS == Inf || LHS == NaN 3741 if (Pred == FCmpInst::FCMP_UEQ && isKnownNeverInfinity(LHS, Q.TLI) && 3742 isKnownNeverNaN(LHS, Q.TLI)) 3743 return getFalse(RetTy); 3744 // LHS != Inf && LHS != NaN 3745 if (Pred == FCmpInst::FCMP_ONE && isKnownNeverInfinity(LHS, Q.TLI) && 3746 isKnownNeverNaN(LHS, Q.TLI)) 3747 return getTrue(RetTy); 3748 } 3749 if (C->isNegative() && !C->isNegZero()) { 3750 assert(!C->isNaN() && "Unexpected NaN constant!"); 3751 // TODO: We can catch more cases by using a range check rather than 3752 // relying on CannotBeOrderedLessThanZero. 3753 switch (Pred) { 3754 case FCmpInst::FCMP_UGE: 3755 case FCmpInst::FCMP_UGT: 3756 case FCmpInst::FCMP_UNE: 3757 // (X >= 0) implies (X > C) when (C < 0) 3758 if (CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3759 return getTrue(RetTy); 3760 break; 3761 case FCmpInst::FCMP_OEQ: 3762 case FCmpInst::FCMP_OLE: 3763 case FCmpInst::FCMP_OLT: 3764 // (X >= 0) implies !(X < C) when (C < 0) 3765 if (CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3766 return getFalse(RetTy); 3767 break; 3768 default: 3769 break; 3770 } 3771 } 3772 3773 // Check comparison of [minnum/maxnum with constant] with other constant. 3774 const APFloat *C2; 3775 if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) && 3776 *C2 < *C) || 3777 (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) && 3778 *C2 > *C)) { 3779 bool IsMaxNum = 3780 cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum; 3781 // The ordered relationship and minnum/maxnum guarantee that we do not 3782 // have NaN constants, so ordered/unordered preds are handled the same. 3783 switch (Pred) { 3784 case FCmpInst::FCMP_OEQ: case FCmpInst::FCMP_UEQ: 3785 // minnum(X, LesserC) == C --> false 3786 // maxnum(X, GreaterC) == C --> false 3787 return getFalse(RetTy); 3788 case FCmpInst::FCMP_ONE: case FCmpInst::FCMP_UNE: 3789 // minnum(X, LesserC) != C --> true 3790 // maxnum(X, GreaterC) != C --> true 3791 return getTrue(RetTy); 3792 case FCmpInst::FCMP_OGE: case FCmpInst::FCMP_UGE: 3793 case FCmpInst::FCMP_OGT: case FCmpInst::FCMP_UGT: 3794 // minnum(X, LesserC) >= C --> false 3795 // minnum(X, LesserC) > C --> false 3796 // maxnum(X, GreaterC) >= C --> true 3797 // maxnum(X, GreaterC) > C --> true 3798 return ConstantInt::get(RetTy, IsMaxNum); 3799 case FCmpInst::FCMP_OLE: case FCmpInst::FCMP_ULE: 3800 case FCmpInst::FCMP_OLT: case FCmpInst::FCMP_ULT: 3801 // minnum(X, LesserC) <= C --> true 3802 // minnum(X, LesserC) < C --> true 3803 // maxnum(X, GreaterC) <= C --> false 3804 // maxnum(X, GreaterC) < C --> false 3805 return ConstantInt::get(RetTy, !IsMaxNum); 3806 default: 3807 // TRUE/FALSE/ORD/UNO should be handled before this. 3808 llvm_unreachable("Unexpected fcmp predicate"); 3809 } 3810 } 3811 } 3812 3813 if (match(RHS, m_AnyZeroFP())) { 3814 switch (Pred) { 3815 case FCmpInst::FCMP_OGE: 3816 case FCmpInst::FCMP_ULT: 3817 // Positive or zero X >= 0.0 --> true 3818 // Positive or zero X < 0.0 --> false 3819 if ((FMF.noNaNs() || isKnownNeverNaN(LHS, Q.TLI)) && 3820 CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3821 return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy); 3822 break; 3823 case FCmpInst::FCMP_UGE: 3824 case FCmpInst::FCMP_OLT: 3825 // Positive or zero or nan X >= 0.0 --> true 3826 // Positive or zero or nan X < 0.0 --> false 3827 if (CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3828 return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy); 3829 break; 3830 default: 3831 break; 3832 } 3833 } 3834 3835 // If the comparison is with the result of a select instruction, check whether 3836 // comparing with either branch of the select always yields the same value. 3837 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 3838 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 3839 return V; 3840 3841 // If the comparison is with the result of a phi instruction, check whether 3842 // doing the compare with each incoming phi value yields a common result. 3843 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 3844 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 3845 return V; 3846 3847 return nullptr; 3848 } 3849 3850 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3851 FastMathFlags FMF, const SimplifyQuery &Q) { 3852 return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit); 3853 } 3854 3855 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 3856 const SimplifyQuery &Q, 3857 bool AllowRefinement, 3858 unsigned MaxRecurse) { 3859 assert(!Op->getType()->isVectorTy() && "This is not safe for vectors"); 3860 3861 // Trivial replacement. 3862 if (V == Op) 3863 return RepOp; 3864 3865 // We cannot replace a constant, and shouldn't even try. 3866 if (isa<Constant>(Op)) 3867 return nullptr; 3868 3869 auto *I = dyn_cast<Instruction>(V); 3870 if (!I || !is_contained(I->operands(), Op)) 3871 return nullptr; 3872 3873 // Replace Op with RepOp in instruction operands. 3874 SmallVector<Value *, 8> NewOps(I->getNumOperands()); 3875 transform(I->operands(), NewOps.begin(), 3876 [&](Value *V) { return V == Op ? RepOp : V; }); 3877 3878 if (!AllowRefinement) { 3879 // General InstSimplify functions may refine the result, e.g. by returning 3880 // a constant for a potentially poison value. To avoid this, implement only 3881 // a few non-refining but profitable transforms here. 3882 3883 if (auto *BO = dyn_cast<BinaryOperator>(I)) { 3884 unsigned Opcode = BO->getOpcode(); 3885 // id op x -> x, x op id -> x 3886 if (NewOps[0] == ConstantExpr::getBinOpIdentity(Opcode, I->getType())) 3887 return NewOps[1]; 3888 if (NewOps[1] == ConstantExpr::getBinOpIdentity(Opcode, I->getType(), 3889 /* RHS */ true)) 3890 return NewOps[0]; 3891 3892 // x & x -> x, x | x -> x 3893 if ((Opcode == Instruction::And || Opcode == Instruction::Or) && 3894 NewOps[0] == NewOps[1]) 3895 return NewOps[0]; 3896 } 3897 3898 if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) { 3899 // getelementptr x, 0 -> x 3900 if (NewOps.size() == 2 && match(NewOps[1], m_Zero()) && 3901 !GEP->isInBounds()) 3902 return NewOps[0]; 3903 } 3904 } else if (MaxRecurse) { 3905 // The simplification queries below may return the original value. Consider: 3906 // %div = udiv i32 %arg, %arg2 3907 // %mul = mul nsw i32 %div, %arg2 3908 // %cmp = icmp eq i32 %mul, %arg 3909 // %sel = select i1 %cmp, i32 %div, i32 undef 3910 // Replacing %arg by %mul, %div becomes "udiv i32 %mul, %arg2", which 3911 // simplifies back to %arg. This can only happen because %mul does not 3912 // dominate %div. To ensure a consistent return value contract, we make sure 3913 // that this case returns nullptr as well. 3914 auto PreventSelfSimplify = [V](Value *Simplified) { 3915 return Simplified != V ? Simplified : nullptr; 3916 }; 3917 3918 if (auto *B = dyn_cast<BinaryOperator>(I)) 3919 return PreventSelfSimplify(SimplifyBinOp(B->getOpcode(), NewOps[0], 3920 NewOps[1], Q, MaxRecurse - 1)); 3921 3922 if (CmpInst *C = dyn_cast<CmpInst>(I)) 3923 return PreventSelfSimplify(SimplifyCmpInst(C->getPredicate(), NewOps[0], 3924 NewOps[1], Q, MaxRecurse - 1)); 3925 3926 if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) 3927 return PreventSelfSimplify(SimplifyGEPInst(GEP->getSourceElementType(), 3928 NewOps, Q, MaxRecurse - 1)); 3929 3930 if (isa<SelectInst>(I)) 3931 return PreventSelfSimplify( 3932 SimplifySelectInst(NewOps[0], NewOps[1], NewOps[2], Q, 3933 MaxRecurse - 1)); 3934 // TODO: We could hand off more cases to instsimplify here. 3935 } 3936 3937 // If all operands are constant after substituting Op for RepOp then we can 3938 // constant fold the instruction. 3939 SmallVector<Constant *, 8> ConstOps; 3940 for (Value *NewOp : NewOps) { 3941 if (Constant *ConstOp = dyn_cast<Constant>(NewOp)) 3942 ConstOps.push_back(ConstOp); 3943 else 3944 return nullptr; 3945 } 3946 3947 // Consider: 3948 // %cmp = icmp eq i32 %x, 2147483647 3949 // %add = add nsw i32 %x, 1 3950 // %sel = select i1 %cmp, i32 -2147483648, i32 %add 3951 // 3952 // We can't replace %sel with %add unless we strip away the flags (which 3953 // will be done in InstCombine). 3954 // TODO: This may be unsound, because it only catches some forms of 3955 // refinement. 3956 if (!AllowRefinement && canCreatePoison(cast<Operator>(I))) 3957 return nullptr; 3958 3959 if (CmpInst *C = dyn_cast<CmpInst>(I)) 3960 return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0], 3961 ConstOps[1], Q.DL, Q.TLI); 3962 3963 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 3964 if (!LI->isVolatile()) 3965 return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL); 3966 3967 return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI); 3968 } 3969 3970 Value *llvm::simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 3971 const SimplifyQuery &Q, 3972 bool AllowRefinement) { 3973 return ::simplifyWithOpReplaced(V, Op, RepOp, Q, AllowRefinement, 3974 RecursionLimit); 3975 } 3976 3977 /// Try to simplify a select instruction when its condition operand is an 3978 /// integer comparison where one operand of the compare is a constant. 3979 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X, 3980 const APInt *Y, bool TrueWhenUnset) { 3981 const APInt *C; 3982 3983 // (X & Y) == 0 ? X & ~Y : X --> X 3984 // (X & Y) != 0 ? X & ~Y : X --> X & ~Y 3985 if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) && 3986 *Y == ~*C) 3987 return TrueWhenUnset ? FalseVal : TrueVal; 3988 3989 // (X & Y) == 0 ? X : X & ~Y --> X & ~Y 3990 // (X & Y) != 0 ? X : X & ~Y --> X 3991 if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) && 3992 *Y == ~*C) 3993 return TrueWhenUnset ? FalseVal : TrueVal; 3994 3995 if (Y->isPowerOf2()) { 3996 // (X & Y) == 0 ? X | Y : X --> X | Y 3997 // (X & Y) != 0 ? X | Y : X --> X 3998 if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) && 3999 *Y == *C) 4000 return TrueWhenUnset ? TrueVal : FalseVal; 4001 4002 // (X & Y) == 0 ? X : X | Y --> X 4003 // (X & Y) != 0 ? X : X | Y --> X | Y 4004 if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) && 4005 *Y == *C) 4006 return TrueWhenUnset ? TrueVal : FalseVal; 4007 } 4008 4009 return nullptr; 4010 } 4011 4012 /// An alternative way to test if a bit is set or not uses sgt/slt instead of 4013 /// eq/ne. 4014 static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS, 4015 ICmpInst::Predicate Pred, 4016 Value *TrueVal, Value *FalseVal) { 4017 Value *X; 4018 APInt Mask; 4019 if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) 4020 return nullptr; 4021 4022 return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask, 4023 Pred == ICmpInst::ICMP_EQ); 4024 } 4025 4026 /// Try to simplify a select instruction when its condition operand is an 4027 /// integer comparison. 4028 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, 4029 Value *FalseVal, const SimplifyQuery &Q, 4030 unsigned MaxRecurse) { 4031 ICmpInst::Predicate Pred; 4032 Value *CmpLHS, *CmpRHS; 4033 if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS)))) 4034 return nullptr; 4035 4036 // Canonicalize ne to eq predicate. 4037 if (Pred == ICmpInst::ICMP_NE) { 4038 Pred = ICmpInst::ICMP_EQ; 4039 std::swap(TrueVal, FalseVal); 4040 } 4041 4042 if (Pred == ICmpInst::ICMP_EQ && match(CmpRHS, m_Zero())) { 4043 Value *X; 4044 const APInt *Y; 4045 if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y)))) 4046 if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y, 4047 /*TrueWhenUnset=*/true)) 4048 return V; 4049 4050 // Test for a bogus zero-shift-guard-op around funnel-shift or rotate. 4051 Value *ShAmt; 4052 auto isFsh = m_CombineOr(m_FShl(m_Value(X), m_Value(), m_Value(ShAmt)), 4053 m_FShr(m_Value(), m_Value(X), m_Value(ShAmt))); 4054 // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X 4055 // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X 4056 if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt) 4057 return X; 4058 4059 // Test for a zero-shift-guard-op around rotates. These are used to 4060 // avoid UB from oversized shifts in raw IR rotate patterns, but the 4061 // intrinsics do not have that problem. 4062 // We do not allow this transform for the general funnel shift case because 4063 // that would not preserve the poison safety of the original code. 4064 auto isRotate = 4065 m_CombineOr(m_FShl(m_Value(X), m_Deferred(X), m_Value(ShAmt)), 4066 m_FShr(m_Value(X), m_Deferred(X), m_Value(ShAmt))); 4067 // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt) 4068 // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt) 4069 if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt && 4070 Pred == ICmpInst::ICMP_EQ) 4071 return FalseVal; 4072 4073 // X == 0 ? abs(X) : -abs(X) --> -abs(X) 4074 // X == 0 ? -abs(X) : abs(X) --> abs(X) 4075 if (match(TrueVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))) && 4076 match(FalseVal, m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))))) 4077 return FalseVal; 4078 if (match(TrueVal, 4079 m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) && 4080 match(FalseVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) 4081 return FalseVal; 4082 } 4083 4084 // Check for other compares that behave like bit test. 4085 if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred, 4086 TrueVal, FalseVal)) 4087 return V; 4088 4089 // If we have a scalar equality comparison, then we know the value in one of 4090 // the arms of the select. See if substituting this value into the arm and 4091 // simplifying the result yields the same value as the other arm. 4092 // Note that the equivalence/replacement opportunity does not hold for vectors 4093 // because each element of a vector select is chosen independently. 4094 if (Pred == ICmpInst::ICMP_EQ && !CondVal->getType()->isVectorTy()) { 4095 if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, 4096 /* AllowRefinement */ false, MaxRecurse) == 4097 TrueVal || 4098 simplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, 4099 /* AllowRefinement */ false, MaxRecurse) == 4100 TrueVal) 4101 return FalseVal; 4102 if (simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, 4103 /* AllowRefinement */ true, MaxRecurse) == 4104 FalseVal || 4105 simplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, 4106 /* AllowRefinement */ true, MaxRecurse) == 4107 FalseVal) 4108 return FalseVal; 4109 } 4110 4111 return nullptr; 4112 } 4113 4114 /// Try to simplify a select instruction when its condition operand is a 4115 /// floating-point comparison. 4116 static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F, 4117 const SimplifyQuery &Q) { 4118 FCmpInst::Predicate Pred; 4119 if (!match(Cond, m_FCmp(Pred, m_Specific(T), m_Specific(F))) && 4120 !match(Cond, m_FCmp(Pred, m_Specific(F), m_Specific(T)))) 4121 return nullptr; 4122 4123 // This transform is safe if we do not have (do not care about) -0.0 or if 4124 // at least one operand is known to not be -0.0. Otherwise, the select can 4125 // change the sign of a zero operand. 4126 bool HasNoSignedZeros = Q.CxtI && isa<FPMathOperator>(Q.CxtI) && 4127 Q.CxtI->hasNoSignedZeros(); 4128 const APFloat *C; 4129 if (HasNoSignedZeros || (match(T, m_APFloat(C)) && C->isNonZero()) || 4130 (match(F, m_APFloat(C)) && C->isNonZero())) { 4131 // (T == F) ? T : F --> F 4132 // (F == T) ? T : F --> F 4133 if (Pred == FCmpInst::FCMP_OEQ) 4134 return F; 4135 4136 // (T != F) ? T : F --> T 4137 // (F != T) ? T : F --> T 4138 if (Pred == FCmpInst::FCMP_UNE) 4139 return T; 4140 } 4141 4142 return nullptr; 4143 } 4144 4145 /// Given operands for a SelectInst, see if we can fold the result. 4146 /// If not, this returns null. 4147 static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4148 const SimplifyQuery &Q, unsigned MaxRecurse) { 4149 if (auto *CondC = dyn_cast<Constant>(Cond)) { 4150 if (auto *TrueC = dyn_cast<Constant>(TrueVal)) 4151 if (auto *FalseC = dyn_cast<Constant>(FalseVal)) 4152 return ConstantFoldSelectInstruction(CondC, TrueC, FalseC); 4153 4154 // select undef, X, Y -> X or Y 4155 if (Q.isUndefValue(CondC)) 4156 return isa<Constant>(FalseVal) ? FalseVal : TrueVal; 4157 4158 // select true, X, Y --> X 4159 // select false, X, Y --> Y 4160 // For vectors, allow undef/poison elements in the condition to match the 4161 // defined elements, so we can eliminate the select. 4162 if (match(CondC, m_One())) 4163 return TrueVal; 4164 if (match(CondC, m_Zero())) 4165 return FalseVal; 4166 } 4167 4168 // select i1 Cond, i1 true, i1 false --> i1 Cond 4169 assert(Cond->getType()->isIntOrIntVectorTy(1) && 4170 "Select must have bool or bool vector condition"); 4171 assert(TrueVal->getType() == FalseVal->getType() && 4172 "Select must have same types for true/false ops"); 4173 if (Cond->getType() == TrueVal->getType() && 4174 match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt())) 4175 return Cond; 4176 4177 // select ?, X, X -> X 4178 if (TrueVal == FalseVal) 4179 return TrueVal; 4180 4181 // If the true or false value is undef, we can fold to the other value as 4182 // long as the other value isn't poison. 4183 // select ?, undef, X -> X 4184 if (Q.isUndefValue(TrueVal) && 4185 isGuaranteedNotToBeUndefOrPoison(FalseVal, Q.AC, Q.CxtI, Q.DT)) 4186 return FalseVal; 4187 // select ?, X, undef -> X 4188 if (Q.isUndefValue(FalseVal) && 4189 isGuaranteedNotToBeUndefOrPoison(TrueVal, Q.AC, Q.CxtI, Q.DT)) 4190 return TrueVal; 4191 4192 // Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC'' 4193 Constant *TrueC, *FalseC; 4194 if (isa<FixedVectorType>(TrueVal->getType()) && 4195 match(TrueVal, m_Constant(TrueC)) && 4196 match(FalseVal, m_Constant(FalseC))) { 4197 unsigned NumElts = 4198 cast<FixedVectorType>(TrueC->getType())->getNumElements(); 4199 SmallVector<Constant *, 16> NewC; 4200 for (unsigned i = 0; i != NumElts; ++i) { 4201 // Bail out on incomplete vector constants. 4202 Constant *TEltC = TrueC->getAggregateElement(i); 4203 Constant *FEltC = FalseC->getAggregateElement(i); 4204 if (!TEltC || !FEltC) 4205 break; 4206 4207 // If the elements match (undef or not), that value is the result. If only 4208 // one element is undef, choose the defined element as the safe result. 4209 if (TEltC == FEltC) 4210 NewC.push_back(TEltC); 4211 else if (Q.isUndefValue(TEltC) && 4212 isGuaranteedNotToBeUndefOrPoison(FEltC)) 4213 NewC.push_back(FEltC); 4214 else if (Q.isUndefValue(FEltC) && 4215 isGuaranteedNotToBeUndefOrPoison(TEltC)) 4216 NewC.push_back(TEltC); 4217 else 4218 break; 4219 } 4220 if (NewC.size() == NumElts) 4221 return ConstantVector::get(NewC); 4222 } 4223 4224 if (Value *V = 4225 simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse)) 4226 return V; 4227 4228 if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q)) 4229 return V; 4230 4231 if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal)) 4232 return V; 4233 4234 Optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL); 4235 if (Imp) 4236 return *Imp ? TrueVal : FalseVal; 4237 4238 return nullptr; 4239 } 4240 4241 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4242 const SimplifyQuery &Q) { 4243 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit); 4244 } 4245 4246 /// Given operands for an GetElementPtrInst, see if we can fold the result. 4247 /// If not, this returns null. 4248 static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, 4249 const SimplifyQuery &Q, unsigned) { 4250 // The type of the GEP pointer operand. 4251 unsigned AS = 4252 cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace(); 4253 4254 // getelementptr P -> P. 4255 if (Ops.size() == 1) 4256 return Ops[0]; 4257 4258 // Compute the (pointer) type returned by the GEP instruction. 4259 Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1)); 4260 Type *GEPTy = PointerType::get(LastType, AS); 4261 for (Value *Op : Ops) { 4262 // If one of the operands is a vector, the result type is a vector of 4263 // pointers. All vector operands must have the same number of elements. 4264 if (VectorType *VT = dyn_cast<VectorType>(Op->getType())) { 4265 GEPTy = VectorType::get(GEPTy, VT->getElementCount()); 4266 break; 4267 } 4268 } 4269 4270 // getelementptr poison, idx -> poison 4271 // getelementptr baseptr, poison -> poison 4272 if (any_of(Ops, [](const auto *V) { return isa<PoisonValue>(V); })) 4273 return PoisonValue::get(GEPTy); 4274 4275 if (Q.isUndefValue(Ops[0])) 4276 return UndefValue::get(GEPTy); 4277 4278 bool IsScalableVec = 4279 isa<ScalableVectorType>(SrcTy) || any_of(Ops, [](const Value *V) { 4280 return isa<ScalableVectorType>(V->getType()); 4281 }); 4282 4283 if (Ops.size() == 2) { 4284 // getelementptr P, 0 -> P. 4285 if (match(Ops[1], m_Zero()) && Ops[0]->getType() == GEPTy) 4286 return Ops[0]; 4287 4288 Type *Ty = SrcTy; 4289 if (!IsScalableVec && Ty->isSized()) { 4290 Value *P; 4291 uint64_t C; 4292 uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty); 4293 // getelementptr P, N -> P if P points to a type of zero size. 4294 if (TyAllocSize == 0 && Ops[0]->getType() == GEPTy) 4295 return Ops[0]; 4296 4297 // The following transforms are only safe if the ptrtoint cast 4298 // doesn't truncate the pointers. 4299 if (Ops[1]->getType()->getScalarSizeInBits() == 4300 Q.DL.getPointerSizeInBits(AS)) { 4301 auto CanSimplify = [GEPTy, &P, V = Ops[0]]() -> bool { 4302 return P->getType() == GEPTy && 4303 getUnderlyingObject(P) == getUnderlyingObject(V); 4304 }; 4305 // getelementptr V, (sub P, V) -> P if P points to a type of size 1. 4306 if (TyAllocSize == 1 && 4307 match(Ops[1], m_Sub(m_PtrToInt(m_Value(P)), 4308 m_PtrToInt(m_Specific(Ops[0])))) && 4309 CanSimplify()) 4310 return P; 4311 4312 // getelementptr V, (ashr (sub P, V), C) -> P if P points to a type of 4313 // size 1 << C. 4314 if (match(Ops[1], m_AShr(m_Sub(m_PtrToInt(m_Value(P)), 4315 m_PtrToInt(m_Specific(Ops[0]))), 4316 m_ConstantInt(C))) && 4317 TyAllocSize == 1ULL << C && CanSimplify()) 4318 return P; 4319 4320 // getelementptr V, (sdiv (sub P, V), C) -> P if P points to a type of 4321 // size C. 4322 if (match(Ops[1], m_SDiv(m_Sub(m_PtrToInt(m_Value(P)), 4323 m_PtrToInt(m_Specific(Ops[0]))), 4324 m_SpecificInt(TyAllocSize))) && 4325 CanSimplify()) 4326 return P; 4327 } 4328 } 4329 } 4330 4331 if (!IsScalableVec && Q.DL.getTypeAllocSize(LastType) == 1 && 4332 all_of(Ops.slice(1).drop_back(1), 4333 [](Value *Idx) { return match(Idx, m_Zero()); })) { 4334 unsigned IdxWidth = 4335 Q.DL.getIndexSizeInBits(Ops[0]->getType()->getPointerAddressSpace()); 4336 if (Q.DL.getTypeSizeInBits(Ops.back()->getType()) == IdxWidth) { 4337 APInt BasePtrOffset(IdxWidth, 0); 4338 Value *StrippedBasePtr = 4339 Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL, 4340 BasePtrOffset); 4341 4342 // Avoid creating inttoptr of zero here: While LLVMs treatment of 4343 // inttoptr is generally conservative, this particular case is folded to 4344 // a null pointer, which will have incorrect provenance. 4345 4346 // gep (gep V, C), (sub 0, V) -> C 4347 if (match(Ops.back(), 4348 m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr)))) && 4349 !BasePtrOffset.isNullValue()) { 4350 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset); 4351 return ConstantExpr::getIntToPtr(CI, GEPTy); 4352 } 4353 // gep (gep V, C), (xor V, -1) -> C-1 4354 if (match(Ops.back(), 4355 m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes())) && 4356 !BasePtrOffset.isOneValue()) { 4357 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1); 4358 return ConstantExpr::getIntToPtr(CI, GEPTy); 4359 } 4360 } 4361 } 4362 4363 // Check to see if this is constant foldable. 4364 if (!all_of(Ops, [](Value *V) { return isa<Constant>(V); })) 4365 return nullptr; 4366 4367 auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]), 4368 Ops.slice(1)); 4369 return ConstantFoldConstant(CE, Q.DL); 4370 } 4371 4372 Value *llvm::SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, 4373 const SimplifyQuery &Q) { 4374 return ::SimplifyGEPInst(SrcTy, Ops, Q, RecursionLimit); 4375 } 4376 4377 /// Given operands for an InsertValueInst, see if we can fold the result. 4378 /// If not, this returns null. 4379 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val, 4380 ArrayRef<unsigned> Idxs, const SimplifyQuery &Q, 4381 unsigned) { 4382 if (Constant *CAgg = dyn_cast<Constant>(Agg)) 4383 if (Constant *CVal = dyn_cast<Constant>(Val)) 4384 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); 4385 4386 // insertvalue x, undef, n -> x 4387 if (Q.isUndefValue(Val)) 4388 return Agg; 4389 4390 // insertvalue x, (extractvalue y, n), n 4391 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) 4392 if (EV->getAggregateOperand()->getType() == Agg->getType() && 4393 EV->getIndices() == Idxs) { 4394 // insertvalue undef, (extractvalue y, n), n -> y 4395 if (Q.isUndefValue(Agg)) 4396 return EV->getAggregateOperand(); 4397 4398 // insertvalue y, (extractvalue y, n), n -> y 4399 if (Agg == EV->getAggregateOperand()) 4400 return Agg; 4401 } 4402 4403 return nullptr; 4404 } 4405 4406 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val, 4407 ArrayRef<unsigned> Idxs, 4408 const SimplifyQuery &Q) { 4409 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit); 4410 } 4411 4412 Value *llvm::SimplifyInsertElementInst(Value *Vec, Value *Val, Value *Idx, 4413 const SimplifyQuery &Q) { 4414 // Try to constant fold. 4415 auto *VecC = dyn_cast<Constant>(Vec); 4416 auto *ValC = dyn_cast<Constant>(Val); 4417 auto *IdxC = dyn_cast<Constant>(Idx); 4418 if (VecC && ValC && IdxC) 4419 return ConstantExpr::getInsertElement(VecC, ValC, IdxC); 4420 4421 // For fixed-length vector, fold into poison if index is out of bounds. 4422 if (auto *CI = dyn_cast<ConstantInt>(Idx)) { 4423 if (isa<FixedVectorType>(Vec->getType()) && 4424 CI->uge(cast<FixedVectorType>(Vec->getType())->getNumElements())) 4425 return PoisonValue::get(Vec->getType()); 4426 } 4427 4428 // If index is undef, it might be out of bounds (see above case) 4429 if (Q.isUndefValue(Idx)) 4430 return PoisonValue::get(Vec->getType()); 4431 4432 // If the scalar is poison, or it is undef and there is no risk of 4433 // propagating poison from the vector value, simplify to the vector value. 4434 if (isa<PoisonValue>(Val) || 4435 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Vec))) 4436 return Vec; 4437 4438 // If we are extracting a value from a vector, then inserting it into the same 4439 // place, that's the input vector: 4440 // insertelt Vec, (extractelt Vec, Idx), Idx --> Vec 4441 if (match(Val, m_ExtractElt(m_Specific(Vec), m_Specific(Idx)))) 4442 return Vec; 4443 4444 return nullptr; 4445 } 4446 4447 /// Given operands for an ExtractValueInst, see if we can fold the result. 4448 /// If not, this returns null. 4449 static Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 4450 const SimplifyQuery &, unsigned) { 4451 if (auto *CAgg = dyn_cast<Constant>(Agg)) 4452 return ConstantFoldExtractValueInstruction(CAgg, Idxs); 4453 4454 // extractvalue x, (insertvalue y, elt, n), n -> elt 4455 unsigned NumIdxs = Idxs.size(); 4456 for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr; 4457 IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) { 4458 ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices(); 4459 unsigned NumInsertValueIdxs = InsertValueIdxs.size(); 4460 unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs); 4461 if (InsertValueIdxs.slice(0, NumCommonIdxs) == 4462 Idxs.slice(0, NumCommonIdxs)) { 4463 if (NumIdxs == NumInsertValueIdxs) 4464 return IVI->getInsertedValueOperand(); 4465 break; 4466 } 4467 } 4468 4469 return nullptr; 4470 } 4471 4472 Value *llvm::SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 4473 const SimplifyQuery &Q) { 4474 return ::SimplifyExtractValueInst(Agg, Idxs, Q, RecursionLimit); 4475 } 4476 4477 /// Given operands for an ExtractElementInst, see if we can fold the result. 4478 /// If not, this returns null. 4479 static Value *SimplifyExtractElementInst(Value *Vec, Value *Idx, 4480 const SimplifyQuery &Q, unsigned) { 4481 auto *VecVTy = cast<VectorType>(Vec->getType()); 4482 if (auto *CVec = dyn_cast<Constant>(Vec)) { 4483 if (auto *CIdx = dyn_cast<Constant>(Idx)) 4484 return ConstantExpr::getExtractElement(CVec, CIdx); 4485 4486 // The index is not relevant if our vector is a splat. 4487 if (auto *Splat = CVec->getSplatValue()) 4488 return Splat; 4489 4490 if (Q.isUndefValue(Vec)) 4491 return UndefValue::get(VecVTy->getElementType()); 4492 } 4493 4494 // If extracting a specified index from the vector, see if we can recursively 4495 // find a previously computed scalar that was inserted into the vector. 4496 if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) { 4497 // For fixed-length vector, fold into undef if index is out of bounds. 4498 unsigned MinNumElts = VecVTy->getElementCount().getKnownMinValue(); 4499 if (isa<FixedVectorType>(VecVTy) && IdxC->getValue().uge(MinNumElts)) 4500 return PoisonValue::get(VecVTy->getElementType()); 4501 // Handle case where an element is extracted from a splat. 4502 if (IdxC->getValue().ult(MinNumElts)) 4503 if (auto *Splat = getSplatValue(Vec)) 4504 return Splat; 4505 if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue())) 4506 return Elt; 4507 } 4508 4509 // An undef extract index can be arbitrarily chosen to be an out-of-range 4510 // index value, which would result in the instruction being poison. 4511 if (Q.isUndefValue(Idx)) 4512 return PoisonValue::get(VecVTy->getElementType()); 4513 4514 return nullptr; 4515 } 4516 4517 Value *llvm::SimplifyExtractElementInst(Value *Vec, Value *Idx, 4518 const SimplifyQuery &Q) { 4519 return ::SimplifyExtractElementInst(Vec, Idx, Q, RecursionLimit); 4520 } 4521 4522 /// See if we can fold the given phi. If not, returns null. 4523 static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) { 4524 // WARNING: no matter how worthwhile it may seem, we can not perform PHI CSE 4525 // here, because the PHI we may succeed simplifying to was not 4526 // def-reachable from the original PHI! 4527 4528 // If all of the PHI's incoming values are the same then replace the PHI node 4529 // with the common value. 4530 Value *CommonValue = nullptr; 4531 bool HasUndefInput = false; 4532 for (Value *Incoming : PN->incoming_values()) { 4533 // If the incoming value is the phi node itself, it can safely be skipped. 4534 if (Incoming == PN) continue; 4535 if (Q.isUndefValue(Incoming)) { 4536 // Remember that we saw an undef value, but otherwise ignore them. 4537 HasUndefInput = true; 4538 continue; 4539 } 4540 if (CommonValue && Incoming != CommonValue) 4541 return nullptr; // Not the same, bail out. 4542 CommonValue = Incoming; 4543 } 4544 4545 // If CommonValue is null then all of the incoming values were either undef or 4546 // equal to the phi node itself. 4547 if (!CommonValue) 4548 return UndefValue::get(PN->getType()); 4549 4550 // If we have a PHI node like phi(X, undef, X), where X is defined by some 4551 // instruction, we cannot return X as the result of the PHI node unless it 4552 // dominates the PHI block. 4553 if (HasUndefInput) 4554 return valueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr; 4555 4556 return CommonValue; 4557 } 4558 4559 static Value *SimplifyCastInst(unsigned CastOpc, Value *Op, 4560 Type *Ty, const SimplifyQuery &Q, unsigned MaxRecurse) { 4561 if (auto *C = dyn_cast<Constant>(Op)) 4562 return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL); 4563 4564 if (auto *CI = dyn_cast<CastInst>(Op)) { 4565 auto *Src = CI->getOperand(0); 4566 Type *SrcTy = Src->getType(); 4567 Type *MidTy = CI->getType(); 4568 Type *DstTy = Ty; 4569 if (Src->getType() == Ty) { 4570 auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode()); 4571 auto SecondOp = static_cast<Instruction::CastOps>(CastOpc); 4572 Type *SrcIntPtrTy = 4573 SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr; 4574 Type *MidIntPtrTy = 4575 MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr; 4576 Type *DstIntPtrTy = 4577 DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr; 4578 if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy, 4579 SrcIntPtrTy, MidIntPtrTy, 4580 DstIntPtrTy) == Instruction::BitCast) 4581 return Src; 4582 } 4583 } 4584 4585 // bitcast x -> x 4586 if (CastOpc == Instruction::BitCast) 4587 if (Op->getType() == Ty) 4588 return Op; 4589 4590 return nullptr; 4591 } 4592 4593 Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 4594 const SimplifyQuery &Q) { 4595 return ::SimplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit); 4596 } 4597 4598 /// For the given destination element of a shuffle, peek through shuffles to 4599 /// match a root vector source operand that contains that element in the same 4600 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s). 4601 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1, 4602 int MaskVal, Value *RootVec, 4603 unsigned MaxRecurse) { 4604 if (!MaxRecurse--) 4605 return nullptr; 4606 4607 // Bail out if any mask value is undefined. That kind of shuffle may be 4608 // simplified further based on demanded bits or other folds. 4609 if (MaskVal == -1) 4610 return nullptr; 4611 4612 // The mask value chooses which source operand we need to look at next. 4613 int InVecNumElts = cast<FixedVectorType>(Op0->getType())->getNumElements(); 4614 int RootElt = MaskVal; 4615 Value *SourceOp = Op0; 4616 if (MaskVal >= InVecNumElts) { 4617 RootElt = MaskVal - InVecNumElts; 4618 SourceOp = Op1; 4619 } 4620 4621 // If the source operand is a shuffle itself, look through it to find the 4622 // matching root vector. 4623 if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) { 4624 return foldIdentityShuffles( 4625 DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1), 4626 SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse); 4627 } 4628 4629 // TODO: Look through bitcasts? What if the bitcast changes the vector element 4630 // size? 4631 4632 // The source operand is not a shuffle. Initialize the root vector value for 4633 // this shuffle if that has not been done yet. 4634 if (!RootVec) 4635 RootVec = SourceOp; 4636 4637 // Give up as soon as a source operand does not match the existing root value. 4638 if (RootVec != SourceOp) 4639 return nullptr; 4640 4641 // The element must be coming from the same lane in the source vector 4642 // (although it may have crossed lanes in intermediate shuffles). 4643 if (RootElt != DestElt) 4644 return nullptr; 4645 4646 return RootVec; 4647 } 4648 4649 static Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, 4650 ArrayRef<int> Mask, Type *RetTy, 4651 const SimplifyQuery &Q, 4652 unsigned MaxRecurse) { 4653 if (all_of(Mask, [](int Elem) { return Elem == UndefMaskElem; })) 4654 return UndefValue::get(RetTy); 4655 4656 auto *InVecTy = cast<VectorType>(Op0->getType()); 4657 unsigned MaskNumElts = Mask.size(); 4658 ElementCount InVecEltCount = InVecTy->getElementCount(); 4659 4660 bool Scalable = InVecEltCount.isScalable(); 4661 4662 SmallVector<int, 32> Indices; 4663 Indices.assign(Mask.begin(), Mask.end()); 4664 4665 // Canonicalization: If mask does not select elements from an input vector, 4666 // replace that input vector with poison. 4667 if (!Scalable) { 4668 bool MaskSelects0 = false, MaskSelects1 = false; 4669 unsigned InVecNumElts = InVecEltCount.getKnownMinValue(); 4670 for (unsigned i = 0; i != MaskNumElts; ++i) { 4671 if (Indices[i] == -1) 4672 continue; 4673 if ((unsigned)Indices[i] < InVecNumElts) 4674 MaskSelects0 = true; 4675 else 4676 MaskSelects1 = true; 4677 } 4678 if (!MaskSelects0) 4679 Op0 = PoisonValue::get(InVecTy); 4680 if (!MaskSelects1) 4681 Op1 = PoisonValue::get(InVecTy); 4682 } 4683 4684 auto *Op0Const = dyn_cast<Constant>(Op0); 4685 auto *Op1Const = dyn_cast<Constant>(Op1); 4686 4687 // If all operands are constant, constant fold the shuffle. This 4688 // transformation depends on the value of the mask which is not known at 4689 // compile time for scalable vectors 4690 if (Op0Const && Op1Const) 4691 return ConstantExpr::getShuffleVector(Op0Const, Op1Const, Mask); 4692 4693 // Canonicalization: if only one input vector is constant, it shall be the 4694 // second one. This transformation depends on the value of the mask which 4695 // is not known at compile time for scalable vectors 4696 if (!Scalable && Op0Const && !Op1Const) { 4697 std::swap(Op0, Op1); 4698 ShuffleVectorInst::commuteShuffleMask(Indices, 4699 InVecEltCount.getKnownMinValue()); 4700 } 4701 4702 // A splat of an inserted scalar constant becomes a vector constant: 4703 // shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...> 4704 // NOTE: We may have commuted above, so analyze the updated Indices, not the 4705 // original mask constant. 4706 // NOTE: This transformation depends on the value of the mask which is not 4707 // known at compile time for scalable vectors 4708 Constant *C; 4709 ConstantInt *IndexC; 4710 if (!Scalable && match(Op0, m_InsertElt(m_Value(), m_Constant(C), 4711 m_ConstantInt(IndexC)))) { 4712 // Match a splat shuffle mask of the insert index allowing undef elements. 4713 int InsertIndex = IndexC->getZExtValue(); 4714 if (all_of(Indices, [InsertIndex](int MaskElt) { 4715 return MaskElt == InsertIndex || MaskElt == -1; 4716 })) { 4717 assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat"); 4718 4719 // Shuffle mask undefs become undefined constant result elements. 4720 SmallVector<Constant *, 16> VecC(MaskNumElts, C); 4721 for (unsigned i = 0; i != MaskNumElts; ++i) 4722 if (Indices[i] == -1) 4723 VecC[i] = UndefValue::get(C->getType()); 4724 return ConstantVector::get(VecC); 4725 } 4726 } 4727 4728 // A shuffle of a splat is always the splat itself. Legal if the shuffle's 4729 // value type is same as the input vectors' type. 4730 if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0)) 4731 if (Q.isUndefValue(Op1) && RetTy == InVecTy && 4732 is_splat(OpShuf->getShuffleMask())) 4733 return Op0; 4734 4735 // All remaining transformation depend on the value of the mask, which is 4736 // not known at compile time for scalable vectors. 4737 if (Scalable) 4738 return nullptr; 4739 4740 // Don't fold a shuffle with undef mask elements. This may get folded in a 4741 // better way using demanded bits or other analysis. 4742 // TODO: Should we allow this? 4743 if (is_contained(Indices, -1)) 4744 return nullptr; 4745 4746 // Check if every element of this shuffle can be mapped back to the 4747 // corresponding element of a single root vector. If so, we don't need this 4748 // shuffle. This handles simple identity shuffles as well as chains of 4749 // shuffles that may widen/narrow and/or move elements across lanes and back. 4750 Value *RootVec = nullptr; 4751 for (unsigned i = 0; i != MaskNumElts; ++i) { 4752 // Note that recursion is limited for each vector element, so if any element 4753 // exceeds the limit, this will fail to simplify. 4754 RootVec = 4755 foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse); 4756 4757 // We can't replace a widening/narrowing shuffle with one of its operands. 4758 if (!RootVec || RootVec->getType() != RetTy) 4759 return nullptr; 4760 } 4761 return RootVec; 4762 } 4763 4764 /// Given operands for a ShuffleVectorInst, fold the result or return null. 4765 Value *llvm::SimplifyShuffleVectorInst(Value *Op0, Value *Op1, 4766 ArrayRef<int> Mask, Type *RetTy, 4767 const SimplifyQuery &Q) { 4768 return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit); 4769 } 4770 4771 static Constant *foldConstant(Instruction::UnaryOps Opcode, 4772 Value *&Op, const SimplifyQuery &Q) { 4773 if (auto *C = dyn_cast<Constant>(Op)) 4774 return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL); 4775 return nullptr; 4776 } 4777 4778 /// Given the operand for an FNeg, see if we can fold the result. If not, this 4779 /// returns null. 4780 static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, 4781 const SimplifyQuery &Q, unsigned MaxRecurse) { 4782 if (Constant *C = foldConstant(Instruction::FNeg, Op, Q)) 4783 return C; 4784 4785 Value *X; 4786 // fneg (fneg X) ==> X 4787 if (match(Op, m_FNeg(m_Value(X)))) 4788 return X; 4789 4790 return nullptr; 4791 } 4792 4793 Value *llvm::SimplifyFNegInst(Value *Op, FastMathFlags FMF, 4794 const SimplifyQuery &Q) { 4795 return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit); 4796 } 4797 4798 static Constant *propagateNaN(Constant *In) { 4799 // If the input is a vector with undef elements, just return a default NaN. 4800 if (!In->isNaN()) 4801 return ConstantFP::getNaN(In->getType()); 4802 4803 // Propagate the existing NaN constant when possible. 4804 // TODO: Should we quiet a signaling NaN? 4805 return In; 4806 } 4807 4808 /// Perform folds that are common to any floating-point operation. This implies 4809 /// transforms based on undef/NaN because the operation itself makes no 4810 /// difference to the result. 4811 static Constant *simplifyFPOp(ArrayRef<Value *> Ops, 4812 FastMathFlags FMF, 4813 const SimplifyQuery &Q) { 4814 for (Value *V : Ops) { 4815 bool IsNan = match(V, m_NaN()); 4816 bool IsInf = match(V, m_Inf()); 4817 bool IsUndef = Q.isUndefValue(V); 4818 4819 // If this operation has 'nnan' or 'ninf' and at least 1 disallowed operand 4820 // (an undef operand can be chosen to be Nan/Inf), then the result of 4821 // this operation is poison. 4822 if (FMF.noNaNs() && (IsNan || IsUndef)) 4823 return PoisonValue::get(V->getType()); 4824 if (FMF.noInfs() && (IsInf || IsUndef)) 4825 return PoisonValue::get(V->getType()); 4826 4827 if (IsUndef || IsNan) 4828 return propagateNaN(cast<Constant>(V)); 4829 } 4830 return nullptr; 4831 } 4832 4833 /// Given operands for an FAdd, see if we can fold the result. If not, this 4834 /// returns null. 4835 static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4836 const SimplifyQuery &Q, unsigned MaxRecurse) { 4837 if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q)) 4838 return C; 4839 4840 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 4841 return C; 4842 4843 // fadd X, -0 ==> X 4844 if (match(Op1, m_NegZeroFP())) 4845 return Op0; 4846 4847 // fadd X, 0 ==> X, when we know X is not -0 4848 if (match(Op1, m_PosZeroFP()) && 4849 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI))) 4850 return Op0; 4851 4852 // With nnan: -X + X --> 0.0 (and commuted variant) 4853 // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN. 4854 // Negative zeros are allowed because we always end up with positive zero: 4855 // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 4856 // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 4857 // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0 4858 // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0 4859 if (FMF.noNaNs()) { 4860 if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || 4861 match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))) 4862 return ConstantFP::getNullValue(Op0->getType()); 4863 4864 if (match(Op0, m_FNeg(m_Specific(Op1))) || 4865 match(Op1, m_FNeg(m_Specific(Op0)))) 4866 return ConstantFP::getNullValue(Op0->getType()); 4867 } 4868 4869 // (X - Y) + Y --> X 4870 // Y + (X - Y) --> X 4871 Value *X; 4872 if (FMF.noSignedZeros() && FMF.allowReassoc() && 4873 (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) || 4874 match(Op1, m_FSub(m_Value(X), m_Specific(Op0))))) 4875 return X; 4876 4877 return nullptr; 4878 } 4879 4880 /// Given operands for an FSub, see if we can fold the result. If not, this 4881 /// returns null. 4882 static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4883 const SimplifyQuery &Q, unsigned MaxRecurse) { 4884 if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q)) 4885 return C; 4886 4887 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 4888 return C; 4889 4890 // fsub X, +0 ==> X 4891 if (match(Op1, m_PosZeroFP())) 4892 return Op0; 4893 4894 // fsub X, -0 ==> X, when we know X is not -0 4895 if (match(Op1, m_NegZeroFP()) && 4896 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI))) 4897 return Op0; 4898 4899 // fsub -0.0, (fsub -0.0, X) ==> X 4900 // fsub -0.0, (fneg X) ==> X 4901 Value *X; 4902 if (match(Op0, m_NegZeroFP()) && 4903 match(Op1, m_FNeg(m_Value(X)))) 4904 return X; 4905 4906 // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored. 4907 // fsub 0.0, (fneg X) ==> X if signed zeros are ignored. 4908 if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) && 4909 (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) || 4910 match(Op1, m_FNeg(m_Value(X))))) 4911 return X; 4912 4913 // fsub nnan x, x ==> 0.0 4914 if (FMF.noNaNs() && Op0 == Op1) 4915 return Constant::getNullValue(Op0->getType()); 4916 4917 // Y - (Y - X) --> X 4918 // (X + Y) - Y --> X 4919 if (FMF.noSignedZeros() && FMF.allowReassoc() && 4920 (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) || 4921 match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X))))) 4922 return X; 4923 4924 return nullptr; 4925 } 4926 4927 static Value *SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 4928 const SimplifyQuery &Q, unsigned MaxRecurse) { 4929 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 4930 return C; 4931 4932 // fmul X, 1.0 ==> X 4933 if (match(Op1, m_FPOne())) 4934 return Op0; 4935 4936 // fmul 1.0, X ==> X 4937 if (match(Op0, m_FPOne())) 4938 return Op1; 4939 4940 // fmul nnan nsz X, 0 ==> 0 4941 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZeroFP())) 4942 return ConstantFP::getNullValue(Op0->getType()); 4943 4944 // fmul nnan nsz 0, X ==> 0 4945 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) 4946 return ConstantFP::getNullValue(Op1->getType()); 4947 4948 // sqrt(X) * sqrt(X) --> X, if we can: 4949 // 1. Remove the intermediate rounding (reassociate). 4950 // 2. Ignore non-zero negative numbers because sqrt would produce NAN. 4951 // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0. 4952 Value *X; 4953 if (Op0 == Op1 && match(Op0, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) && 4954 FMF.allowReassoc() && FMF.noNaNs() && FMF.noSignedZeros()) 4955 return X; 4956 4957 return nullptr; 4958 } 4959 4960 /// Given the operands for an FMul, see if we can fold the result 4961 static Value *SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4962 const SimplifyQuery &Q, unsigned MaxRecurse) { 4963 if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q)) 4964 return C; 4965 4966 // Now apply simplifications that do not require rounding. 4967 return SimplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse); 4968 } 4969 4970 Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4971 const SimplifyQuery &Q) { 4972 return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit); 4973 } 4974 4975 4976 Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4977 const SimplifyQuery &Q) { 4978 return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit); 4979 } 4980 4981 Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4982 const SimplifyQuery &Q) { 4983 return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit); 4984 } 4985 4986 Value *llvm::SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 4987 const SimplifyQuery &Q) { 4988 return ::SimplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit); 4989 } 4990 4991 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4992 const SimplifyQuery &Q, unsigned) { 4993 if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q)) 4994 return C; 4995 4996 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 4997 return C; 4998 4999 // X / 1.0 -> X 5000 if (match(Op1, m_FPOne())) 5001 return Op0; 5002 5003 // 0 / X -> 0 5004 // Requires that NaNs are off (X could be zero) and signed zeroes are 5005 // ignored (X could be positive or negative, so the output sign is unknown). 5006 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) 5007 return ConstantFP::getNullValue(Op0->getType()); 5008 5009 if (FMF.noNaNs()) { 5010 // X / X -> 1.0 is legal when NaNs are ignored. 5011 // We can ignore infinities because INF/INF is NaN. 5012 if (Op0 == Op1) 5013 return ConstantFP::get(Op0->getType(), 1.0); 5014 5015 // (X * Y) / Y --> X if we can reassociate to the above form. 5016 Value *X; 5017 if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1)))) 5018 return X; 5019 5020 // -X / X -> -1.0 and 5021 // X / -X -> -1.0 are legal when NaNs are ignored. 5022 // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored. 5023 if (match(Op0, m_FNegNSZ(m_Specific(Op1))) || 5024 match(Op1, m_FNegNSZ(m_Specific(Op0)))) 5025 return ConstantFP::get(Op0->getType(), -1.0); 5026 } 5027 5028 return nullptr; 5029 } 5030 5031 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5032 const SimplifyQuery &Q) { 5033 return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit); 5034 } 5035 5036 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5037 const SimplifyQuery &Q, unsigned) { 5038 if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q)) 5039 return C; 5040 5041 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 5042 return C; 5043 5044 // Unlike fdiv, the result of frem always matches the sign of the dividend. 5045 // The constant match may include undef elements in a vector, so return a full 5046 // zero constant as the result. 5047 if (FMF.noNaNs()) { 5048 // +0 % X -> 0 5049 if (match(Op0, m_PosZeroFP())) 5050 return ConstantFP::getNullValue(Op0->getType()); 5051 // -0 % X -> -0 5052 if (match(Op0, m_NegZeroFP())) 5053 return ConstantFP::getNegativeZero(Op0->getType()); 5054 } 5055 5056 return nullptr; 5057 } 5058 5059 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5060 const SimplifyQuery &Q) { 5061 return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit); 5062 } 5063 5064 //=== Helper functions for higher up the class hierarchy. 5065 5066 /// Given the operand for a UnaryOperator, see if we can fold the result. 5067 /// If not, this returns null. 5068 static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q, 5069 unsigned MaxRecurse) { 5070 switch (Opcode) { 5071 case Instruction::FNeg: 5072 return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse); 5073 default: 5074 llvm_unreachable("Unexpected opcode"); 5075 } 5076 } 5077 5078 /// Given the operand for a UnaryOperator, see if we can fold the result. 5079 /// If not, this returns null. 5080 /// Try to use FastMathFlags when folding the result. 5081 static Value *simplifyFPUnOp(unsigned Opcode, Value *Op, 5082 const FastMathFlags &FMF, 5083 const SimplifyQuery &Q, unsigned MaxRecurse) { 5084 switch (Opcode) { 5085 case Instruction::FNeg: 5086 return simplifyFNegInst(Op, FMF, Q, MaxRecurse); 5087 default: 5088 return simplifyUnOp(Opcode, Op, Q, MaxRecurse); 5089 } 5090 } 5091 5092 Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) { 5093 return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit); 5094 } 5095 5096 Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 5097 const SimplifyQuery &Q) { 5098 return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit); 5099 } 5100 5101 /// Given operands for a BinaryOperator, see if we can fold the result. 5102 /// If not, this returns null. 5103 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5104 const SimplifyQuery &Q, unsigned MaxRecurse) { 5105 switch (Opcode) { 5106 case Instruction::Add: 5107 return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse); 5108 case Instruction::Sub: 5109 return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse); 5110 case Instruction::Mul: 5111 return SimplifyMulInst(LHS, RHS, Q, MaxRecurse); 5112 case Instruction::SDiv: 5113 return SimplifySDivInst(LHS, RHS, Q, MaxRecurse); 5114 case Instruction::UDiv: 5115 return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse); 5116 case Instruction::SRem: 5117 return SimplifySRemInst(LHS, RHS, Q, MaxRecurse); 5118 case Instruction::URem: 5119 return SimplifyURemInst(LHS, RHS, Q, MaxRecurse); 5120 case Instruction::Shl: 5121 return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse); 5122 case Instruction::LShr: 5123 return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse); 5124 case Instruction::AShr: 5125 return SimplifyAShrInst(LHS, RHS, false, Q, MaxRecurse); 5126 case Instruction::And: 5127 return SimplifyAndInst(LHS, RHS, Q, MaxRecurse); 5128 case Instruction::Or: 5129 return SimplifyOrInst(LHS, RHS, Q, MaxRecurse); 5130 case Instruction::Xor: 5131 return SimplifyXorInst(LHS, RHS, Q, MaxRecurse); 5132 case Instruction::FAdd: 5133 return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5134 case Instruction::FSub: 5135 return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5136 case Instruction::FMul: 5137 return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5138 case Instruction::FDiv: 5139 return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5140 case Instruction::FRem: 5141 return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5142 default: 5143 llvm_unreachable("Unexpected opcode"); 5144 } 5145 } 5146 5147 /// Given operands for a BinaryOperator, see if we can fold the result. 5148 /// If not, this returns null. 5149 /// Try to use FastMathFlags when folding the result. 5150 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5151 const FastMathFlags &FMF, const SimplifyQuery &Q, 5152 unsigned MaxRecurse) { 5153 switch (Opcode) { 5154 case Instruction::FAdd: 5155 return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse); 5156 case Instruction::FSub: 5157 return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse); 5158 case Instruction::FMul: 5159 return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse); 5160 case Instruction::FDiv: 5161 return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse); 5162 default: 5163 return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse); 5164 } 5165 } 5166 5167 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5168 const SimplifyQuery &Q) { 5169 return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit); 5170 } 5171 5172 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5173 FastMathFlags FMF, const SimplifyQuery &Q) { 5174 return ::SimplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit); 5175 } 5176 5177 /// Given operands for a CmpInst, see if we can fold the result. 5178 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 5179 const SimplifyQuery &Q, unsigned MaxRecurse) { 5180 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 5181 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 5182 return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5183 } 5184 5185 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 5186 const SimplifyQuery &Q) { 5187 return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 5188 } 5189 5190 static bool IsIdempotent(Intrinsic::ID ID) { 5191 switch (ID) { 5192 default: return false; 5193 5194 // Unary idempotent: f(f(x)) = f(x) 5195 case Intrinsic::fabs: 5196 case Intrinsic::floor: 5197 case Intrinsic::ceil: 5198 case Intrinsic::trunc: 5199 case Intrinsic::rint: 5200 case Intrinsic::nearbyint: 5201 case Intrinsic::round: 5202 case Intrinsic::roundeven: 5203 case Intrinsic::canonicalize: 5204 return true; 5205 } 5206 } 5207 5208 static Value *SimplifyRelativeLoad(Constant *Ptr, Constant *Offset, 5209 const DataLayout &DL) { 5210 GlobalValue *PtrSym; 5211 APInt PtrOffset; 5212 if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL)) 5213 return nullptr; 5214 5215 Type *Int8PtrTy = Type::getInt8PtrTy(Ptr->getContext()); 5216 Type *Int32Ty = Type::getInt32Ty(Ptr->getContext()); 5217 Type *Int32PtrTy = Int32Ty->getPointerTo(); 5218 Type *Int64Ty = Type::getInt64Ty(Ptr->getContext()); 5219 5220 auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset); 5221 if (!OffsetConstInt || OffsetConstInt->getType()->getBitWidth() > 64) 5222 return nullptr; 5223 5224 uint64_t OffsetInt = OffsetConstInt->getSExtValue(); 5225 if (OffsetInt % 4 != 0) 5226 return nullptr; 5227 5228 Constant *C = ConstantExpr::getGetElementPtr( 5229 Int32Ty, ConstantExpr::getBitCast(Ptr, Int32PtrTy), 5230 ConstantInt::get(Int64Ty, OffsetInt / 4)); 5231 Constant *Loaded = ConstantFoldLoadFromConstPtr(C, Int32Ty, DL); 5232 if (!Loaded) 5233 return nullptr; 5234 5235 auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded); 5236 if (!LoadedCE) 5237 return nullptr; 5238 5239 if (LoadedCE->getOpcode() == Instruction::Trunc) { 5240 LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 5241 if (!LoadedCE) 5242 return nullptr; 5243 } 5244 5245 if (LoadedCE->getOpcode() != Instruction::Sub) 5246 return nullptr; 5247 5248 auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 5249 if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt) 5250 return nullptr; 5251 auto *LoadedLHSPtr = LoadedLHS->getOperand(0); 5252 5253 Constant *LoadedRHS = LoadedCE->getOperand(1); 5254 GlobalValue *LoadedRHSSym; 5255 APInt LoadedRHSOffset; 5256 if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset, 5257 DL) || 5258 PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset) 5259 return nullptr; 5260 5261 return ConstantExpr::getBitCast(LoadedLHSPtr, Int8PtrTy); 5262 } 5263 5264 static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0, 5265 const SimplifyQuery &Q) { 5266 // Idempotent functions return the same result when called repeatedly. 5267 Intrinsic::ID IID = F->getIntrinsicID(); 5268 if (IsIdempotent(IID)) 5269 if (auto *II = dyn_cast<IntrinsicInst>(Op0)) 5270 if (II->getIntrinsicID() == IID) 5271 return II; 5272 5273 Value *X; 5274 switch (IID) { 5275 case Intrinsic::fabs: 5276 if (SignBitMustBeZero(Op0, Q.TLI)) return Op0; 5277 break; 5278 case Intrinsic::bswap: 5279 // bswap(bswap(x)) -> x 5280 if (match(Op0, m_BSwap(m_Value(X)))) return X; 5281 break; 5282 case Intrinsic::bitreverse: 5283 // bitreverse(bitreverse(x)) -> x 5284 if (match(Op0, m_BitReverse(m_Value(X)))) return X; 5285 break; 5286 case Intrinsic::ctpop: { 5287 // If everything but the lowest bit is zero, that bit is the pop-count. Ex: 5288 // ctpop(and X, 1) --> and X, 1 5289 unsigned BitWidth = Op0->getType()->getScalarSizeInBits(); 5290 if (MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, BitWidth - 1), 5291 Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 5292 return Op0; 5293 break; 5294 } 5295 case Intrinsic::exp: 5296 // exp(log(x)) -> x 5297 if (Q.CxtI->hasAllowReassoc() && 5298 match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X)))) return X; 5299 break; 5300 case Intrinsic::exp2: 5301 // exp2(log2(x)) -> x 5302 if (Q.CxtI->hasAllowReassoc() && 5303 match(Op0, m_Intrinsic<Intrinsic::log2>(m_Value(X)))) return X; 5304 break; 5305 case Intrinsic::log: 5306 // log(exp(x)) -> x 5307 if (Q.CxtI->hasAllowReassoc() && 5308 match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X)))) return X; 5309 break; 5310 case Intrinsic::log2: 5311 // log2(exp2(x)) -> x 5312 if (Q.CxtI->hasAllowReassoc() && 5313 (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) || 5314 match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0), 5315 m_Value(X))))) return X; 5316 break; 5317 case Intrinsic::log10: 5318 // log10(pow(10.0, x)) -> x 5319 if (Q.CxtI->hasAllowReassoc() && 5320 match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), 5321 m_Value(X)))) return X; 5322 break; 5323 case Intrinsic::floor: 5324 case Intrinsic::trunc: 5325 case Intrinsic::ceil: 5326 case Intrinsic::round: 5327 case Intrinsic::roundeven: 5328 case Intrinsic::nearbyint: 5329 case Intrinsic::rint: { 5330 // floor (sitofp x) -> sitofp x 5331 // floor (uitofp x) -> uitofp x 5332 // 5333 // Converting from int always results in a finite integral number or 5334 // infinity. For either of those inputs, these rounding functions always 5335 // return the same value, so the rounding can be eliminated. 5336 if (match(Op0, m_SIToFP(m_Value())) || match(Op0, m_UIToFP(m_Value()))) 5337 return Op0; 5338 break; 5339 } 5340 case Intrinsic::experimental_vector_reverse: 5341 // experimental.vector.reverse(experimental.vector.reverse(x)) -> x 5342 if (match(Op0, 5343 m_Intrinsic<Intrinsic::experimental_vector_reverse>(m_Value(X)))) 5344 return X; 5345 break; 5346 default: 5347 break; 5348 } 5349 5350 return nullptr; 5351 } 5352 5353 static APInt getMaxMinLimit(Intrinsic::ID IID, unsigned BitWidth) { 5354 switch (IID) { 5355 case Intrinsic::smax: return APInt::getSignedMaxValue(BitWidth); 5356 case Intrinsic::smin: return APInt::getSignedMinValue(BitWidth); 5357 case Intrinsic::umax: return APInt::getMaxValue(BitWidth); 5358 case Intrinsic::umin: return APInt::getMinValue(BitWidth); 5359 default: llvm_unreachable("Unexpected intrinsic"); 5360 } 5361 } 5362 5363 static ICmpInst::Predicate getMaxMinPredicate(Intrinsic::ID IID) { 5364 switch (IID) { 5365 case Intrinsic::smax: return ICmpInst::ICMP_SGE; 5366 case Intrinsic::smin: return ICmpInst::ICMP_SLE; 5367 case Intrinsic::umax: return ICmpInst::ICMP_UGE; 5368 case Intrinsic::umin: return ICmpInst::ICMP_ULE; 5369 default: llvm_unreachable("Unexpected intrinsic"); 5370 } 5371 } 5372 5373 /// Given a min/max intrinsic, see if it can be removed based on having an 5374 /// operand that is another min/max intrinsic with shared operand(s). The caller 5375 /// is expected to swap the operand arguments to handle commutation. 5376 static Value *foldMinMaxSharedOp(Intrinsic::ID IID, Value *Op0, Value *Op1) { 5377 Value *X, *Y; 5378 if (!match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y)))) 5379 return nullptr; 5380 5381 auto *MM0 = dyn_cast<IntrinsicInst>(Op0); 5382 if (!MM0) 5383 return nullptr; 5384 Intrinsic::ID IID0 = MM0->getIntrinsicID(); 5385 5386 if (Op1 == X || Op1 == Y || 5387 match(Op1, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) { 5388 // max (max X, Y), X --> max X, Y 5389 if (IID0 == IID) 5390 return MM0; 5391 // max (min X, Y), X --> X 5392 if (IID0 == getInverseMinMaxIntrinsic(IID)) 5393 return Op1; 5394 } 5395 return nullptr; 5396 } 5397 5398 static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1, 5399 const SimplifyQuery &Q) { 5400 Intrinsic::ID IID = F->getIntrinsicID(); 5401 Type *ReturnType = F->getReturnType(); 5402 unsigned BitWidth = ReturnType->getScalarSizeInBits(); 5403 switch (IID) { 5404 case Intrinsic::abs: 5405 // abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here. 5406 // It is always ok to pick the earlier abs. We'll just lose nsw if its only 5407 // on the outer abs. 5408 if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(), m_Value()))) 5409 return Op0; 5410 break; 5411 5412 case Intrinsic::cttz: { 5413 Value *X; 5414 if (match(Op0, m_Shl(m_One(), m_Value(X)))) 5415 return X; 5416 break; 5417 } 5418 case Intrinsic::ctlz: { 5419 Value *X; 5420 if (match(Op0, m_LShr(m_Negative(), m_Value(X)))) 5421 return X; 5422 if (match(Op0, m_AShr(m_Negative(), m_Value()))) 5423 return Constant::getNullValue(ReturnType); 5424 break; 5425 } 5426 case Intrinsic::smax: 5427 case Intrinsic::smin: 5428 case Intrinsic::umax: 5429 case Intrinsic::umin: { 5430 // If the arguments are the same, this is a no-op. 5431 if (Op0 == Op1) 5432 return Op0; 5433 5434 // Canonicalize constant operand as Op1. 5435 if (isa<Constant>(Op0)) 5436 std::swap(Op0, Op1); 5437 5438 // Assume undef is the limit value. 5439 if (Q.isUndefValue(Op1)) 5440 return ConstantInt::get(ReturnType, getMaxMinLimit(IID, BitWidth)); 5441 5442 const APInt *C; 5443 if (match(Op1, m_APIntAllowUndef(C))) { 5444 // Clamp to limit value. For example: 5445 // umax(i8 %x, i8 255) --> 255 5446 if (*C == getMaxMinLimit(IID, BitWidth)) 5447 return ConstantInt::get(ReturnType, *C); 5448 5449 // If the constant op is the opposite of the limit value, the other must 5450 // be larger/smaller or equal. For example: 5451 // umin(i8 %x, i8 255) --> %x 5452 if (*C == getMaxMinLimit(getInverseMinMaxIntrinsic(IID), BitWidth)) 5453 return Op0; 5454 5455 // Remove nested call if constant operands allow it. Example: 5456 // max (max X, 7), 5 -> max X, 7 5457 auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0); 5458 if (MinMax0 && MinMax0->getIntrinsicID() == IID) { 5459 // TODO: loosen undef/splat restrictions for vector constants. 5460 Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1); 5461 const APInt *InnerC; 5462 if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) && 5463 ((IID == Intrinsic::smax && InnerC->sge(*C)) || 5464 (IID == Intrinsic::smin && InnerC->sle(*C)) || 5465 (IID == Intrinsic::umax && InnerC->uge(*C)) || 5466 (IID == Intrinsic::umin && InnerC->ule(*C)))) 5467 return Op0; 5468 } 5469 } 5470 5471 if (Value *V = foldMinMaxSharedOp(IID, Op0, Op1)) 5472 return V; 5473 if (Value *V = foldMinMaxSharedOp(IID, Op1, Op0)) 5474 return V; 5475 5476 ICmpInst::Predicate Pred = getMaxMinPredicate(IID); 5477 if (isICmpTrue(Pred, Op0, Op1, Q.getWithoutUndef(), RecursionLimit)) 5478 return Op0; 5479 if (isICmpTrue(Pred, Op1, Op0, Q.getWithoutUndef(), RecursionLimit)) 5480 return Op1; 5481 5482 if (Optional<bool> Imp = 5483 isImpliedByDomCondition(Pred, Op0, Op1, Q.CxtI, Q.DL)) 5484 return *Imp ? Op0 : Op1; 5485 if (Optional<bool> Imp = 5486 isImpliedByDomCondition(Pred, Op1, Op0, Q.CxtI, Q.DL)) 5487 return *Imp ? Op1 : Op0; 5488 5489 break; 5490 } 5491 case Intrinsic::usub_with_overflow: 5492 case Intrinsic::ssub_with_overflow: 5493 // X - X -> { 0, false } 5494 // X - undef -> { 0, false } 5495 // undef - X -> { 0, false } 5496 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5497 return Constant::getNullValue(ReturnType); 5498 break; 5499 case Intrinsic::uadd_with_overflow: 5500 case Intrinsic::sadd_with_overflow: 5501 // X + undef -> { -1, false } 5502 // undef + x -> { -1, false } 5503 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) { 5504 return ConstantStruct::get( 5505 cast<StructType>(ReturnType), 5506 {Constant::getAllOnesValue(ReturnType->getStructElementType(0)), 5507 Constant::getNullValue(ReturnType->getStructElementType(1))}); 5508 } 5509 break; 5510 case Intrinsic::umul_with_overflow: 5511 case Intrinsic::smul_with_overflow: 5512 // 0 * X -> { 0, false } 5513 // X * 0 -> { 0, false } 5514 if (match(Op0, m_Zero()) || match(Op1, m_Zero())) 5515 return Constant::getNullValue(ReturnType); 5516 // undef * X -> { 0, false } 5517 // X * undef -> { 0, false } 5518 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5519 return Constant::getNullValue(ReturnType); 5520 break; 5521 case Intrinsic::uadd_sat: 5522 // sat(MAX + X) -> MAX 5523 // sat(X + MAX) -> MAX 5524 if (match(Op0, m_AllOnes()) || match(Op1, m_AllOnes())) 5525 return Constant::getAllOnesValue(ReturnType); 5526 LLVM_FALLTHROUGH; 5527 case Intrinsic::sadd_sat: 5528 // sat(X + undef) -> -1 5529 // sat(undef + X) -> -1 5530 // For unsigned: Assume undef is MAX, thus we saturate to MAX (-1). 5531 // For signed: Assume undef is ~X, in which case X + ~X = -1. 5532 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5533 return Constant::getAllOnesValue(ReturnType); 5534 5535 // X + 0 -> X 5536 if (match(Op1, m_Zero())) 5537 return Op0; 5538 // 0 + X -> X 5539 if (match(Op0, m_Zero())) 5540 return Op1; 5541 break; 5542 case Intrinsic::usub_sat: 5543 // sat(0 - X) -> 0, sat(X - MAX) -> 0 5544 if (match(Op0, m_Zero()) || match(Op1, m_AllOnes())) 5545 return Constant::getNullValue(ReturnType); 5546 LLVM_FALLTHROUGH; 5547 case Intrinsic::ssub_sat: 5548 // X - X -> 0, X - undef -> 0, undef - X -> 0 5549 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5550 return Constant::getNullValue(ReturnType); 5551 // X - 0 -> X 5552 if (match(Op1, m_Zero())) 5553 return Op0; 5554 break; 5555 case Intrinsic::load_relative: 5556 if (auto *C0 = dyn_cast<Constant>(Op0)) 5557 if (auto *C1 = dyn_cast<Constant>(Op1)) 5558 return SimplifyRelativeLoad(C0, C1, Q.DL); 5559 break; 5560 case Intrinsic::powi: 5561 if (auto *Power = dyn_cast<ConstantInt>(Op1)) { 5562 // powi(x, 0) -> 1.0 5563 if (Power->isZero()) 5564 return ConstantFP::get(Op0->getType(), 1.0); 5565 // powi(x, 1) -> x 5566 if (Power->isOne()) 5567 return Op0; 5568 } 5569 break; 5570 case Intrinsic::copysign: 5571 // copysign X, X --> X 5572 if (Op0 == Op1) 5573 return Op0; 5574 // copysign -X, X --> X 5575 // copysign X, -X --> -X 5576 if (match(Op0, m_FNeg(m_Specific(Op1))) || 5577 match(Op1, m_FNeg(m_Specific(Op0)))) 5578 return Op1; 5579 break; 5580 case Intrinsic::maxnum: 5581 case Intrinsic::minnum: 5582 case Intrinsic::maximum: 5583 case Intrinsic::minimum: { 5584 // If the arguments are the same, this is a no-op. 5585 if (Op0 == Op1) return Op0; 5586 5587 // Canonicalize constant operand as Op1. 5588 if (isa<Constant>(Op0)) 5589 std::swap(Op0, Op1); 5590 5591 // If an argument is undef, return the other argument. 5592 if (Q.isUndefValue(Op1)) 5593 return Op0; 5594 5595 bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum; 5596 bool IsMin = IID == Intrinsic::minimum || IID == Intrinsic::minnum; 5597 5598 // minnum(X, nan) -> X 5599 // maxnum(X, nan) -> X 5600 // minimum(X, nan) -> nan 5601 // maximum(X, nan) -> nan 5602 if (match(Op1, m_NaN())) 5603 return PropagateNaN ? propagateNaN(cast<Constant>(Op1)) : Op0; 5604 5605 // In the following folds, inf can be replaced with the largest finite 5606 // float, if the ninf flag is set. 5607 const APFloat *C; 5608 if (match(Op1, m_APFloat(C)) && 5609 (C->isInfinity() || (Q.CxtI->hasNoInfs() && C->isLargest()))) { 5610 // minnum(X, -inf) -> -inf 5611 // maxnum(X, +inf) -> +inf 5612 // minimum(X, -inf) -> -inf if nnan 5613 // maximum(X, +inf) -> +inf if nnan 5614 if (C->isNegative() == IsMin && (!PropagateNaN || Q.CxtI->hasNoNaNs())) 5615 return ConstantFP::get(ReturnType, *C); 5616 5617 // minnum(X, +inf) -> X if nnan 5618 // maxnum(X, -inf) -> X if nnan 5619 // minimum(X, +inf) -> X 5620 // maximum(X, -inf) -> X 5621 if (C->isNegative() != IsMin && (PropagateNaN || Q.CxtI->hasNoNaNs())) 5622 return Op0; 5623 } 5624 5625 // Min/max of the same operation with common operand: 5626 // m(m(X, Y)), X --> m(X, Y) (4 commuted variants) 5627 if (auto *M0 = dyn_cast<IntrinsicInst>(Op0)) 5628 if (M0->getIntrinsicID() == IID && 5629 (M0->getOperand(0) == Op1 || M0->getOperand(1) == Op1)) 5630 return Op0; 5631 if (auto *M1 = dyn_cast<IntrinsicInst>(Op1)) 5632 if (M1->getIntrinsicID() == IID && 5633 (M1->getOperand(0) == Op0 || M1->getOperand(1) == Op0)) 5634 return Op1; 5635 5636 break; 5637 } 5638 case Intrinsic::experimental_vector_extract: { 5639 Type *ReturnType = F->getReturnType(); 5640 5641 // (extract_vector (insert_vector _, X, 0), 0) -> X 5642 unsigned IdxN = cast<ConstantInt>(Op1)->getZExtValue(); 5643 Value *X = nullptr; 5644 if (match(Op0, m_Intrinsic<Intrinsic::experimental_vector_insert>( 5645 m_Value(), m_Value(X), m_Zero())) && 5646 IdxN == 0 && X->getType() == ReturnType) 5647 return X; 5648 5649 break; 5650 } 5651 default: 5652 break; 5653 } 5654 5655 return nullptr; 5656 } 5657 5658 static Value *simplifyIntrinsic(CallBase *Call, const SimplifyQuery &Q) { 5659 5660 // Intrinsics with no operands have some kind of side effect. Don't simplify. 5661 unsigned NumOperands = Call->getNumArgOperands(); 5662 if (!NumOperands) 5663 return nullptr; 5664 5665 Function *F = cast<Function>(Call->getCalledFunction()); 5666 Intrinsic::ID IID = F->getIntrinsicID(); 5667 if (NumOperands == 1) 5668 return simplifyUnaryIntrinsic(F, Call->getArgOperand(0), Q); 5669 5670 if (NumOperands == 2) 5671 return simplifyBinaryIntrinsic(F, Call->getArgOperand(0), 5672 Call->getArgOperand(1), Q); 5673 5674 // Handle intrinsics with 3 or more arguments. 5675 switch (IID) { 5676 case Intrinsic::masked_load: 5677 case Intrinsic::masked_gather: { 5678 Value *MaskArg = Call->getArgOperand(2); 5679 Value *PassthruArg = Call->getArgOperand(3); 5680 // If the mask is all zeros or undef, the "passthru" argument is the result. 5681 if (maskIsAllZeroOrUndef(MaskArg)) 5682 return PassthruArg; 5683 return nullptr; 5684 } 5685 case Intrinsic::fshl: 5686 case Intrinsic::fshr: { 5687 Value *Op0 = Call->getArgOperand(0), *Op1 = Call->getArgOperand(1), 5688 *ShAmtArg = Call->getArgOperand(2); 5689 5690 // If both operands are undef, the result is undef. 5691 if (Q.isUndefValue(Op0) && Q.isUndefValue(Op1)) 5692 return UndefValue::get(F->getReturnType()); 5693 5694 // If shift amount is undef, assume it is zero. 5695 if (Q.isUndefValue(ShAmtArg)) 5696 return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1); 5697 5698 const APInt *ShAmtC; 5699 if (match(ShAmtArg, m_APInt(ShAmtC))) { 5700 // If there's effectively no shift, return the 1st arg or 2nd arg. 5701 APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth()); 5702 if (ShAmtC->urem(BitWidth).isNullValue()) 5703 return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1); 5704 } 5705 return nullptr; 5706 } 5707 case Intrinsic::fma: 5708 case Intrinsic::fmuladd: { 5709 Value *Op0 = Call->getArgOperand(0); 5710 Value *Op1 = Call->getArgOperand(1); 5711 Value *Op2 = Call->getArgOperand(2); 5712 if (Value *V = simplifyFPOp({ Op0, Op1, Op2 }, {}, Q)) 5713 return V; 5714 return nullptr; 5715 } 5716 case Intrinsic::smul_fix: 5717 case Intrinsic::smul_fix_sat: { 5718 Value *Op0 = Call->getArgOperand(0); 5719 Value *Op1 = Call->getArgOperand(1); 5720 Value *Op2 = Call->getArgOperand(2); 5721 Type *ReturnType = F->getReturnType(); 5722 5723 // Canonicalize constant operand as Op1 (ConstantFolding handles the case 5724 // when both Op0 and Op1 are constant so we do not care about that special 5725 // case here). 5726 if (isa<Constant>(Op0)) 5727 std::swap(Op0, Op1); 5728 5729 // X * 0 -> 0 5730 if (match(Op1, m_Zero())) 5731 return Constant::getNullValue(ReturnType); 5732 5733 // X * undef -> 0 5734 if (Q.isUndefValue(Op1)) 5735 return Constant::getNullValue(ReturnType); 5736 5737 // X * (1 << Scale) -> X 5738 APInt ScaledOne = 5739 APInt::getOneBitSet(ReturnType->getScalarSizeInBits(), 5740 cast<ConstantInt>(Op2)->getZExtValue()); 5741 if (ScaledOne.isNonNegative() && match(Op1, m_SpecificInt(ScaledOne))) 5742 return Op0; 5743 5744 return nullptr; 5745 } 5746 case Intrinsic::experimental_vector_insert: { 5747 Value *Vec = Call->getArgOperand(0); 5748 Value *SubVec = Call->getArgOperand(1); 5749 Value *Idx = Call->getArgOperand(2); 5750 Type *ReturnType = F->getReturnType(); 5751 5752 // (insert_vector Y, (extract_vector X, 0), 0) -> X 5753 // where: Y is X, or Y is undef 5754 unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue(); 5755 Value *X = nullptr; 5756 if (match(SubVec, m_Intrinsic<Intrinsic::experimental_vector_extract>( 5757 m_Value(X), m_Zero())) && 5758 (Q.isUndefValue(Vec) || Vec == X) && IdxN == 0 && 5759 X->getType() == ReturnType) 5760 return X; 5761 5762 return nullptr; 5763 } 5764 default: 5765 return nullptr; 5766 } 5767 } 5768 5769 static Value *tryConstantFoldCall(CallBase *Call, const SimplifyQuery &Q) { 5770 auto *F = dyn_cast<Function>(Call->getCalledOperand()); 5771 if (!F || !canConstantFoldCallTo(Call, F)) 5772 return nullptr; 5773 5774 SmallVector<Constant *, 4> ConstantArgs; 5775 unsigned NumArgs = Call->getNumArgOperands(); 5776 ConstantArgs.reserve(NumArgs); 5777 for (auto &Arg : Call->args()) { 5778 Constant *C = dyn_cast<Constant>(&Arg); 5779 if (!C) { 5780 if (isa<MetadataAsValue>(Arg.get())) 5781 continue; 5782 return nullptr; 5783 } 5784 ConstantArgs.push_back(C); 5785 } 5786 5787 return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI); 5788 } 5789 5790 Value *llvm::SimplifyCall(CallBase *Call, const SimplifyQuery &Q) { 5791 // musttail calls can only be simplified if they are also DCEd. 5792 // As we can't guarantee this here, don't simplify them. 5793 if (Call->isMustTailCall()) 5794 return nullptr; 5795 5796 // call undef -> poison 5797 // call null -> poison 5798 Value *Callee = Call->getCalledOperand(); 5799 if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee)) 5800 return PoisonValue::get(Call->getType()); 5801 5802 if (Value *V = tryConstantFoldCall(Call, Q)) 5803 return V; 5804 5805 auto *F = dyn_cast<Function>(Callee); 5806 if (F && F->isIntrinsic()) 5807 if (Value *Ret = simplifyIntrinsic(Call, Q)) 5808 return Ret; 5809 5810 return nullptr; 5811 } 5812 5813 /// Given operands for a Freeze, see if we can fold the result. 5814 static Value *SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 5815 // Use a utility function defined in ValueTracking. 5816 if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT)) 5817 return Op0; 5818 // We have room for improvement. 5819 return nullptr; 5820 } 5821 5822 Value *llvm::SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 5823 return ::SimplifyFreezeInst(Op0, Q); 5824 } 5825 5826 /// See if we can compute a simplified version of this instruction. 5827 /// If not, this returns null. 5828 5829 Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ, 5830 OptimizationRemarkEmitter *ORE) { 5831 const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I); 5832 Value *Result; 5833 5834 switch (I->getOpcode()) { 5835 default: 5836 Result = ConstantFoldInstruction(I, Q.DL, Q.TLI); 5837 break; 5838 case Instruction::FNeg: 5839 Result = SimplifyFNegInst(I->getOperand(0), I->getFastMathFlags(), Q); 5840 break; 5841 case Instruction::FAdd: 5842 Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1), 5843 I->getFastMathFlags(), Q); 5844 break; 5845 case Instruction::Add: 5846 Result = 5847 SimplifyAddInst(I->getOperand(0), I->getOperand(1), 5848 Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 5849 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); 5850 break; 5851 case Instruction::FSub: 5852 Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1), 5853 I->getFastMathFlags(), Q); 5854 break; 5855 case Instruction::Sub: 5856 Result = 5857 SimplifySubInst(I->getOperand(0), I->getOperand(1), 5858 Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 5859 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); 5860 break; 5861 case Instruction::FMul: 5862 Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1), 5863 I->getFastMathFlags(), Q); 5864 break; 5865 case Instruction::Mul: 5866 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), Q); 5867 break; 5868 case Instruction::SDiv: 5869 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), Q); 5870 break; 5871 case Instruction::UDiv: 5872 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), Q); 5873 break; 5874 case Instruction::FDiv: 5875 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), 5876 I->getFastMathFlags(), Q); 5877 break; 5878 case Instruction::SRem: 5879 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), Q); 5880 break; 5881 case Instruction::URem: 5882 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), Q); 5883 break; 5884 case Instruction::FRem: 5885 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), 5886 I->getFastMathFlags(), Q); 5887 break; 5888 case Instruction::Shl: 5889 Result = 5890 SimplifyShlInst(I->getOperand(0), I->getOperand(1), 5891 Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 5892 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); 5893 break; 5894 case Instruction::LShr: 5895 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), 5896 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q); 5897 break; 5898 case Instruction::AShr: 5899 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), 5900 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q); 5901 break; 5902 case Instruction::And: 5903 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), Q); 5904 break; 5905 case Instruction::Or: 5906 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), Q); 5907 break; 5908 case Instruction::Xor: 5909 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), Q); 5910 break; 5911 case Instruction::ICmp: 5912 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), 5913 I->getOperand(0), I->getOperand(1), Q); 5914 break; 5915 case Instruction::FCmp: 5916 Result = 5917 SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0), 5918 I->getOperand(1), I->getFastMathFlags(), Q); 5919 break; 5920 case Instruction::Select: 5921 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), 5922 I->getOperand(2), Q); 5923 break; 5924 case Instruction::GetElementPtr: { 5925 SmallVector<Value *, 8> Ops(I->operands()); 5926 Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(), 5927 Ops, Q); 5928 break; 5929 } 5930 case Instruction::InsertValue: { 5931 InsertValueInst *IV = cast<InsertValueInst>(I); 5932 Result = SimplifyInsertValueInst(IV->getAggregateOperand(), 5933 IV->getInsertedValueOperand(), 5934 IV->getIndices(), Q); 5935 break; 5936 } 5937 case Instruction::InsertElement: { 5938 auto *IE = cast<InsertElementInst>(I); 5939 Result = SimplifyInsertElementInst(IE->getOperand(0), IE->getOperand(1), 5940 IE->getOperand(2), Q); 5941 break; 5942 } 5943 case Instruction::ExtractValue: { 5944 auto *EVI = cast<ExtractValueInst>(I); 5945 Result = SimplifyExtractValueInst(EVI->getAggregateOperand(), 5946 EVI->getIndices(), Q); 5947 break; 5948 } 5949 case Instruction::ExtractElement: { 5950 auto *EEI = cast<ExtractElementInst>(I); 5951 Result = SimplifyExtractElementInst(EEI->getVectorOperand(), 5952 EEI->getIndexOperand(), Q); 5953 break; 5954 } 5955 case Instruction::ShuffleVector: { 5956 auto *SVI = cast<ShuffleVectorInst>(I); 5957 Result = 5958 SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1), 5959 SVI->getShuffleMask(), SVI->getType(), Q); 5960 break; 5961 } 5962 case Instruction::PHI: 5963 Result = SimplifyPHINode(cast<PHINode>(I), Q); 5964 break; 5965 case Instruction::Call: { 5966 Result = SimplifyCall(cast<CallInst>(I), Q); 5967 break; 5968 } 5969 case Instruction::Freeze: 5970 Result = SimplifyFreezeInst(I->getOperand(0), Q); 5971 break; 5972 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc: 5973 #include "llvm/IR/Instruction.def" 5974 #undef HANDLE_CAST_INST 5975 Result = 5976 SimplifyCastInst(I->getOpcode(), I->getOperand(0), I->getType(), Q); 5977 break; 5978 case Instruction::Alloca: 5979 // No simplifications for Alloca and it can't be constant folded. 5980 Result = nullptr; 5981 break; 5982 } 5983 5984 /// If called on unreachable code, the above logic may report that the 5985 /// instruction simplified to itself. Make life easier for users by 5986 /// detecting that case here, returning a safe value instead. 5987 return Result == I ? UndefValue::get(I->getType()) : Result; 5988 } 5989 5990 /// Implementation of recursive simplification through an instruction's 5991 /// uses. 5992 /// 5993 /// This is the common implementation of the recursive simplification routines. 5994 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to 5995 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of 5996 /// instructions to process and attempt to simplify it using 5997 /// InstructionSimplify. Recursively visited users which could not be 5998 /// simplified themselves are to the optional UnsimplifiedUsers set for 5999 /// further processing by the caller. 6000 /// 6001 /// This routine returns 'true' only when *it* simplifies something. The passed 6002 /// in simplified value does not count toward this. 6003 static bool replaceAndRecursivelySimplifyImpl( 6004 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 6005 const DominatorTree *DT, AssumptionCache *AC, 6006 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) { 6007 bool Simplified = false; 6008 SmallSetVector<Instruction *, 8> Worklist; 6009 const DataLayout &DL = I->getModule()->getDataLayout(); 6010 6011 // If we have an explicit value to collapse to, do that round of the 6012 // simplification loop by hand initially. 6013 if (SimpleV) { 6014 for (User *U : I->users()) 6015 if (U != I) 6016 Worklist.insert(cast<Instruction>(U)); 6017 6018 // Replace the instruction with its simplified value. 6019 I->replaceAllUsesWith(SimpleV); 6020 6021 // Gracefully handle edge cases where the instruction is not wired into any 6022 // parent block. 6023 if (I->getParent() && !I->isEHPad() && !I->isTerminator() && 6024 !I->mayHaveSideEffects()) 6025 I->eraseFromParent(); 6026 } else { 6027 Worklist.insert(I); 6028 } 6029 6030 // Note that we must test the size on each iteration, the worklist can grow. 6031 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { 6032 I = Worklist[Idx]; 6033 6034 // See if this instruction simplifies. 6035 SimpleV = SimplifyInstruction(I, {DL, TLI, DT, AC}); 6036 if (!SimpleV) { 6037 if (UnsimplifiedUsers) 6038 UnsimplifiedUsers->insert(I); 6039 continue; 6040 } 6041 6042 Simplified = true; 6043 6044 // Stash away all the uses of the old instruction so we can check them for 6045 // recursive simplifications after a RAUW. This is cheaper than checking all 6046 // uses of To on the recursive step in most cases. 6047 for (User *U : I->users()) 6048 Worklist.insert(cast<Instruction>(U)); 6049 6050 // Replace the instruction with its simplified value. 6051 I->replaceAllUsesWith(SimpleV); 6052 6053 // Gracefully handle edge cases where the instruction is not wired into any 6054 // parent block. 6055 if (I->getParent() && !I->isEHPad() && !I->isTerminator() && 6056 !I->mayHaveSideEffects()) 6057 I->eraseFromParent(); 6058 } 6059 return Simplified; 6060 } 6061 6062 bool llvm::replaceAndRecursivelySimplify( 6063 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 6064 const DominatorTree *DT, AssumptionCache *AC, 6065 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) { 6066 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!"); 6067 assert(SimpleV && "Must provide a simplified value."); 6068 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC, 6069 UnsimplifiedUsers); 6070 } 6071 6072 namespace llvm { 6073 const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) { 6074 auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>(); 6075 auto *DT = DTWP ? &DTWP->getDomTree() : nullptr; 6076 auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>(); 6077 auto *TLI = TLIWP ? &TLIWP->getTLI(F) : nullptr; 6078 auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>(); 6079 auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr; 6080 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 6081 } 6082 6083 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR, 6084 const DataLayout &DL) { 6085 return {DL, &AR.TLI, &AR.DT, &AR.AC}; 6086 } 6087 6088 template <class T, class... TArgs> 6089 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM, 6090 Function &F) { 6091 auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F); 6092 auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F); 6093 auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F); 6094 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 6095 } 6096 template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &, 6097 Function &); 6098 } 6099