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/ValueTracking.h" 30 #include "llvm/Analysis/VectorUtils.h" 31 #include "llvm/IR/ConstantRange.h" 32 #include "llvm/IR/DataLayout.h" 33 #include "llvm/IR/Dominators.h" 34 #include "llvm/IR/GetElementPtrTypeIterator.h" 35 #include "llvm/IR/GlobalAlias.h" 36 #include "llvm/IR/InstrTypes.h" 37 #include "llvm/IR/Instructions.h" 38 #include "llvm/IR/Operator.h" 39 #include "llvm/IR/PatternMatch.h" 40 #include "llvm/IR/ValueHandle.h" 41 #include "llvm/Support/KnownBits.h" 42 #include <algorithm> 43 using namespace llvm; 44 using namespace llvm::PatternMatch; 45 46 #define DEBUG_TYPE "instsimplify" 47 48 enum { RecursionLimit = 3 }; 49 50 STATISTIC(NumExpand, "Number of expansions"); 51 STATISTIC(NumReassoc, "Number of reassociations"); 52 53 static Value *SimplifyAndInst(Value *, Value *, const SimplifyQuery &, unsigned); 54 static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned); 55 static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &, 56 const SimplifyQuery &, unsigned); 57 static Value *SimplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &, 58 unsigned); 59 static Value *SimplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &, 60 const SimplifyQuery &, unsigned); 61 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &, 62 unsigned); 63 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 64 const SimplifyQuery &Q, unsigned MaxRecurse); 65 static Value *SimplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned); 66 static Value *SimplifyXorInst(Value *, Value *, const SimplifyQuery &, unsigned); 67 static Value *SimplifyCastInst(unsigned, Value *, Type *, 68 const SimplifyQuery &, unsigned); 69 static Value *SimplifyGEPInst(Type *, ArrayRef<Value *>, const SimplifyQuery &, 70 unsigned); 71 72 static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal, 73 Value *FalseVal) { 74 BinaryOperator::BinaryOps BinOpCode; 75 if (auto *BO = dyn_cast<BinaryOperator>(Cond)) 76 BinOpCode = BO->getOpcode(); 77 else 78 return nullptr; 79 80 CmpInst::Predicate ExpectedPred, Pred1, Pred2; 81 if (BinOpCode == BinaryOperator::Or) { 82 ExpectedPred = ICmpInst::ICMP_NE; 83 } else if (BinOpCode == BinaryOperator::And) { 84 ExpectedPred = ICmpInst::ICMP_EQ; 85 } else 86 return nullptr; 87 88 // %A = icmp eq %TV, %FV 89 // %B = icmp eq %X, %Y (and one of these is a select operand) 90 // %C = and %A, %B 91 // %D = select %C, %TV, %FV 92 // --> 93 // %FV 94 95 // %A = icmp ne %TV, %FV 96 // %B = icmp ne %X, %Y (and one of these is a select operand) 97 // %C = or %A, %B 98 // %D = select %C, %TV, %FV 99 // --> 100 // %TV 101 Value *X, *Y; 102 if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal), 103 m_Specific(FalseVal)), 104 m_ICmp(Pred2, m_Value(X), m_Value(Y)))) || 105 Pred1 != Pred2 || Pred1 != ExpectedPred) 106 return nullptr; 107 108 if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal) 109 return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal; 110 111 return nullptr; 112 } 113 114 /// For a boolean type or a vector of boolean type, return false or a vector 115 /// with every element false. 116 static Constant *getFalse(Type *Ty) { 117 return ConstantInt::getFalse(Ty); 118 } 119 120 /// For a boolean type or a vector of boolean type, return true or a vector 121 /// with every element true. 122 static Constant *getTrue(Type *Ty) { 123 return ConstantInt::getTrue(Ty); 124 } 125 126 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? 127 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, 128 Value *RHS) { 129 CmpInst *Cmp = dyn_cast<CmpInst>(V); 130 if (!Cmp) 131 return false; 132 CmpInst::Predicate CPred = Cmp->getPredicate(); 133 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); 134 if (CPred == Pred && CLHS == LHS && CRHS == RHS) 135 return true; 136 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && 137 CRHS == LHS; 138 } 139 140 /// Simplify comparison with true or false branch of select: 141 /// %sel = select i1 %cond, i32 %tv, i32 %fv 142 /// %cmp = icmp sle i32 %sel, %rhs 143 /// Compose new comparison by substituting %sel with either %tv or %fv 144 /// and see if it simplifies. 145 static Value *simplifyCmpSelCase(CmpInst::Predicate Pred, Value *LHS, 146 Value *RHS, Value *Cond, 147 const SimplifyQuery &Q, unsigned MaxRecurse, 148 Constant *TrueOrFalse) { 149 Value *SimplifiedCmp = SimplifyCmpInst(Pred, LHS, RHS, Q, MaxRecurse); 150 if (SimplifiedCmp == Cond) { 151 // %cmp simplified to the select condition (%cond). 152 return TrueOrFalse; 153 } else if (!SimplifiedCmp && isSameCompare(Cond, Pred, LHS, RHS)) { 154 // It didn't simplify. However, if composed comparison is equivalent 155 // to the select condition (%cond) then we can replace it. 156 return TrueOrFalse; 157 } 158 return SimplifiedCmp; 159 } 160 161 /// Simplify comparison with true branch of select 162 static Value *simplifyCmpSelTrueCase(CmpInst::Predicate Pred, Value *LHS, 163 Value *RHS, Value *Cond, 164 const SimplifyQuery &Q, 165 unsigned MaxRecurse) { 166 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 167 getTrue(Cond->getType())); 168 } 169 170 /// Simplify comparison with false branch of select 171 static Value *simplifyCmpSelFalseCase(CmpInst::Predicate Pred, Value *LHS, 172 Value *RHS, Value *Cond, 173 const SimplifyQuery &Q, 174 unsigned MaxRecurse) { 175 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 176 getFalse(Cond->getType())); 177 } 178 179 /// We know comparison with both branches of select can be simplified, but they 180 /// are not equal. This routine handles some logical simplifications. 181 static Value *handleOtherCmpSelSimplifications(Value *TCmp, Value *FCmp, 182 Value *Cond, 183 const SimplifyQuery &Q, 184 unsigned MaxRecurse) { 185 // If the false value simplified to false, then the result of the compare 186 // is equal to "Cond && TCmp". This also catches the case when the false 187 // value simplified to false and the true value to true, returning "Cond". 188 if (match(FCmp, m_Zero())) 189 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse)) 190 return V; 191 // If the true value simplified to true, then the result of the compare 192 // is equal to "Cond || FCmp". 193 if (match(TCmp, m_One())) 194 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse)) 195 return V; 196 // Finally, if the false value simplified to true and the true value to 197 // false, then the result of the compare is equal to "!Cond". 198 if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 199 if (Value *V = SimplifyXorInst( 200 Cond, Constant::getAllOnesValue(Cond->getType()), Q, MaxRecurse)) 201 return V; 202 return nullptr; 203 } 204 205 /// Does the given value dominate the specified phi node? 206 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 207 Instruction *I = dyn_cast<Instruction>(V); 208 if (!I) 209 // Arguments and constants dominate all instructions. 210 return true; 211 212 // If we are processing instructions (and/or basic blocks) that have not been 213 // fully added to a function, the parent nodes may still be null. Simply 214 // return the conservative answer in these cases. 215 if (!I->getParent() || !P->getParent() || !I->getFunction()) 216 return false; 217 218 // If we have a DominatorTree then do a precise test. 219 if (DT) 220 return DT->dominates(I, P); 221 222 // Otherwise, if the instruction is in the entry block and is not an invoke, 223 // then it obviously dominates all phi nodes. 224 if (I->getParent() == &I->getFunction()->getEntryBlock() && 225 !isa<InvokeInst>(I) && !isa<CallBrInst>(I)) 226 return true; 227 228 return false; 229 } 230 231 /// Try to simplify a binary operator of form "V op OtherOp" where V is 232 /// "(B0 opex B1)" by distributing 'op' across 'opex' as 233 /// "(B0 op OtherOp) opex (B1 op OtherOp)". 234 static Value *expandBinOp(Instruction::BinaryOps Opcode, Value *V, 235 Value *OtherOp, Instruction::BinaryOps OpcodeToExpand, 236 const SimplifyQuery &Q, unsigned MaxRecurse) { 237 auto *B = dyn_cast<BinaryOperator>(V); 238 if (!B || B->getOpcode() != OpcodeToExpand) 239 return nullptr; 240 Value *B0 = B->getOperand(0), *B1 = B->getOperand(1); 241 Value *L = SimplifyBinOp(Opcode, B0, OtherOp, Q.getWithoutUndef(), 242 MaxRecurse); 243 if (!L) 244 return nullptr; 245 Value *R = SimplifyBinOp(Opcode, B1, OtherOp, Q.getWithoutUndef(), 246 MaxRecurse); 247 if (!R) 248 return nullptr; 249 250 // Does the expanded pair of binops simplify to the existing binop? 251 if ((L == B0 && R == B1) || 252 (Instruction::isCommutative(OpcodeToExpand) && L == B1 && R == B0)) { 253 ++NumExpand; 254 return B; 255 } 256 257 // Otherwise, return "L op' R" if it simplifies. 258 Value *S = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse); 259 if (!S) 260 return nullptr; 261 262 ++NumExpand; 263 return S; 264 } 265 266 /// Try to simplify binops of form "A op (B op' C)" or the commuted variant by 267 /// distributing op over op'. 268 static Value *expandCommutativeBinOp(Instruction::BinaryOps Opcode, 269 Value *L, Value *R, 270 Instruction::BinaryOps OpcodeToExpand, 271 const SimplifyQuery &Q, 272 unsigned MaxRecurse) { 273 // Recursion is always used, so bail out at once if we already hit the limit. 274 if (!MaxRecurse--) 275 return nullptr; 276 277 if (Value *V = expandBinOp(Opcode, L, R, OpcodeToExpand, Q, MaxRecurse)) 278 return V; 279 if (Value *V = expandBinOp(Opcode, R, L, OpcodeToExpand, Q, MaxRecurse)) 280 return V; 281 return nullptr; 282 } 283 284 /// Generic simplifications for associative binary operations. 285 /// Returns the simpler value, or null if none was found. 286 static Value *SimplifyAssociativeBinOp(Instruction::BinaryOps Opcode, 287 Value *LHS, Value *RHS, 288 const SimplifyQuery &Q, 289 unsigned MaxRecurse) { 290 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 291 292 // Recursion is always used, so bail out at once if we already hit the limit. 293 if (!MaxRecurse--) 294 return nullptr; 295 296 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 297 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 298 299 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 300 if (Op0 && Op0->getOpcode() == Opcode) { 301 Value *A = Op0->getOperand(0); 302 Value *B = Op0->getOperand(1); 303 Value *C = RHS; 304 305 // Does "B op C" simplify? 306 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 307 // It does! Return "A op V" if it simplifies or is already available. 308 // If V equals B then "A op V" is just the LHS. 309 if (V == B) return LHS; 310 // Otherwise return "A op V" if it simplifies. 311 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { 312 ++NumReassoc; 313 return W; 314 } 315 } 316 } 317 318 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 319 if (Op1 && Op1->getOpcode() == Opcode) { 320 Value *A = LHS; 321 Value *B = Op1->getOperand(0); 322 Value *C = Op1->getOperand(1); 323 324 // Does "A op B" simplify? 325 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { 326 // It does! Return "V op C" if it simplifies or is already available. 327 // If V equals B then "V op C" is just the RHS. 328 if (V == B) return RHS; 329 // Otherwise return "V op C" if it simplifies. 330 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { 331 ++NumReassoc; 332 return W; 333 } 334 } 335 } 336 337 // The remaining transforms require commutativity as well as associativity. 338 if (!Instruction::isCommutative(Opcode)) 339 return nullptr; 340 341 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 342 if (Op0 && Op0->getOpcode() == Opcode) { 343 Value *A = Op0->getOperand(0); 344 Value *B = Op0->getOperand(1); 345 Value *C = RHS; 346 347 // Does "C op A" simplify? 348 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 349 // It does! Return "V op B" if it simplifies or is already available. 350 // If V equals A then "V op B" is just the LHS. 351 if (V == A) return LHS; 352 // Otherwise return "V op B" if it simplifies. 353 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { 354 ++NumReassoc; 355 return W; 356 } 357 } 358 } 359 360 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 361 if (Op1 && Op1->getOpcode() == Opcode) { 362 Value *A = LHS; 363 Value *B = Op1->getOperand(0); 364 Value *C = Op1->getOperand(1); 365 366 // Does "C op A" simplify? 367 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 368 // It does! Return "B op V" if it simplifies or is already available. 369 // If V equals C then "B op V" is just the RHS. 370 if (V == C) return RHS; 371 // Otherwise return "B op V" if it simplifies. 372 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { 373 ++NumReassoc; 374 return W; 375 } 376 } 377 } 378 379 return nullptr; 380 } 381 382 /// In the case of a binary operation with a select instruction as an operand, 383 /// try to simplify the binop by seeing whether evaluating it on both branches 384 /// of the select results in the same value. Returns the common value if so, 385 /// otherwise returns null. 386 static Value *ThreadBinOpOverSelect(Instruction::BinaryOps Opcode, Value *LHS, 387 Value *RHS, const SimplifyQuery &Q, 388 unsigned MaxRecurse) { 389 // Recursion is always used, so bail out at once if we already hit the limit. 390 if (!MaxRecurse--) 391 return nullptr; 392 393 SelectInst *SI; 394 if (isa<SelectInst>(LHS)) { 395 SI = cast<SelectInst>(LHS); 396 } else { 397 assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 398 SI = cast<SelectInst>(RHS); 399 } 400 401 // Evaluate the BinOp on the true and false branches of the select. 402 Value *TV; 403 Value *FV; 404 if (SI == LHS) { 405 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); 406 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); 407 } else { 408 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); 409 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); 410 } 411 412 // If they simplified to the same value, then return the common value. 413 // If they both failed to simplify then return null. 414 if (TV == FV) 415 return TV; 416 417 // If one branch simplified to undef, return the other one. 418 if (TV && Q.isUndefValue(TV)) 419 return FV; 420 if (FV && Q.isUndefValue(FV)) 421 return TV; 422 423 // If applying the operation did not change the true and false select values, 424 // then the result of the binop is the select itself. 425 if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 426 return SI; 427 428 // If one branch simplified and the other did not, and the simplified 429 // value is equal to the unsimplified one, return the simplified value. 430 // For example, select (cond, X, X & Z) & Z -> X & Z. 431 if ((FV && !TV) || (TV && !FV)) { 432 // Check that the simplified value has the form "X op Y" where "op" is the 433 // same as the original operation. 434 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 435 if (Simplified && Simplified->getOpcode() == unsigned(Opcode)) { 436 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 437 // We already know that "op" is the same as for the simplified value. See 438 // if the operands match too. If so, return the simplified value. 439 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 440 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 441 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 442 if (Simplified->getOperand(0) == UnsimplifiedLHS && 443 Simplified->getOperand(1) == UnsimplifiedRHS) 444 return Simplified; 445 if (Simplified->isCommutative() && 446 Simplified->getOperand(1) == UnsimplifiedLHS && 447 Simplified->getOperand(0) == UnsimplifiedRHS) 448 return Simplified; 449 } 450 } 451 452 return nullptr; 453 } 454 455 /// In the case of a comparison with a select instruction, try to simplify the 456 /// comparison by seeing whether both branches of the select result in the same 457 /// value. Returns the common value if so, otherwise returns null. 458 /// For example, if we have: 459 /// %tmp = select i1 %cmp, i32 1, i32 2 460 /// %cmp1 = icmp sle i32 %tmp, 3 461 /// We can simplify %cmp1 to true, because both branches of select are 462 /// less than 3. We compose new comparison by substituting %tmp with both 463 /// branches of select and see if it can be simplified. 464 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 465 Value *RHS, const SimplifyQuery &Q, 466 unsigned MaxRecurse) { 467 // Recursion is always used, so bail out at once if we already hit the limit. 468 if (!MaxRecurse--) 469 return nullptr; 470 471 // Make sure the select is on the LHS. 472 if (!isa<SelectInst>(LHS)) { 473 std::swap(LHS, RHS); 474 Pred = CmpInst::getSwappedPredicate(Pred); 475 } 476 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 477 SelectInst *SI = cast<SelectInst>(LHS); 478 Value *Cond = SI->getCondition(); 479 Value *TV = SI->getTrueValue(); 480 Value *FV = SI->getFalseValue(); 481 482 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 483 // Does "cmp TV, RHS" simplify? 484 Value *TCmp = simplifyCmpSelTrueCase(Pred, TV, RHS, Cond, Q, MaxRecurse); 485 if (!TCmp) 486 return nullptr; 487 488 // Does "cmp FV, RHS" simplify? 489 Value *FCmp = simplifyCmpSelFalseCase(Pred, FV, RHS, Cond, Q, MaxRecurse); 490 if (!FCmp) 491 return nullptr; 492 493 // If both sides simplified to the same value, then use it as the result of 494 // the original comparison. 495 if (TCmp == FCmp) 496 return TCmp; 497 498 // The remaining cases only make sense if the select condition has the same 499 // type as the result of the comparison, so bail out if this is not so. 500 if (Cond->getType()->isVectorTy() == RHS->getType()->isVectorTy()) 501 return handleOtherCmpSelSimplifications(TCmp, FCmp, Cond, Q, MaxRecurse); 502 503 return nullptr; 504 } 505 506 /// In the case of a binary operation with an operand that is a PHI instruction, 507 /// try to simplify the binop by seeing whether evaluating it on the incoming 508 /// phi values yields the same result for every value. If so returns the common 509 /// value, otherwise returns null. 510 static Value *ThreadBinOpOverPHI(Instruction::BinaryOps Opcode, Value *LHS, 511 Value *RHS, const SimplifyQuery &Q, 512 unsigned MaxRecurse) { 513 // Recursion is always used, so bail out at once if we already hit the limit. 514 if (!MaxRecurse--) 515 return nullptr; 516 517 PHINode *PI; 518 if (isa<PHINode>(LHS)) { 519 PI = cast<PHINode>(LHS); 520 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 521 if (!valueDominatesPHI(RHS, PI, Q.DT)) 522 return nullptr; 523 } else { 524 assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 525 PI = cast<PHINode>(RHS); 526 // Bail out if LHS and the phi may be mutually interdependent due to a loop. 527 if (!valueDominatesPHI(LHS, PI, Q.DT)) 528 return nullptr; 529 } 530 531 // Evaluate the BinOp on the incoming phi values. 532 Value *CommonValue = nullptr; 533 for (Value *Incoming : PI->incoming_values()) { 534 // If the incoming value is the phi node itself, it can safely be skipped. 535 if (Incoming == PI) continue; 536 Value *V = PI == LHS ? 537 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) : 538 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse); 539 // If the operation failed to simplify, or simplified to a different value 540 // to previously, then give up. 541 if (!V || (CommonValue && V != CommonValue)) 542 return nullptr; 543 CommonValue = V; 544 } 545 546 return CommonValue; 547 } 548 549 /// In the case of a comparison with a PHI instruction, try to simplify the 550 /// comparison by seeing whether comparing with all of the incoming phi values 551 /// yields the same result every time. If so returns the common result, 552 /// otherwise returns null. 553 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 554 const SimplifyQuery &Q, unsigned MaxRecurse) { 555 // Recursion is always used, so bail out at once if we already hit the limit. 556 if (!MaxRecurse--) 557 return nullptr; 558 559 // Make sure the phi is on the LHS. 560 if (!isa<PHINode>(LHS)) { 561 std::swap(LHS, RHS); 562 Pred = CmpInst::getSwappedPredicate(Pred); 563 } 564 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 565 PHINode *PI = cast<PHINode>(LHS); 566 567 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 568 if (!valueDominatesPHI(RHS, PI, Q.DT)) 569 return nullptr; 570 571 // Evaluate the BinOp on the incoming phi values. 572 Value *CommonValue = nullptr; 573 for (unsigned u = 0, e = PI->getNumIncomingValues(); u < e; ++u) { 574 Value *Incoming = PI->getIncomingValue(u); 575 Instruction *InTI = PI->getIncomingBlock(u)->getTerminator(); 576 // If the incoming value is the phi node itself, it can safely be skipped. 577 if (Incoming == PI) continue; 578 // Change the context instruction to the "edge" that flows into the phi. 579 // This is important because that is where incoming is actually "evaluated" 580 // even though it is used later somewhere else. 581 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q.getWithInstruction(InTI), 582 MaxRecurse); 583 // If the operation failed to simplify, or simplified to a different value 584 // to previously, then give up. 585 if (!V || (CommonValue && V != CommonValue)) 586 return nullptr; 587 CommonValue = V; 588 } 589 590 return CommonValue; 591 } 592 593 static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode, 594 Value *&Op0, Value *&Op1, 595 const SimplifyQuery &Q) { 596 if (auto *CLHS = dyn_cast<Constant>(Op0)) { 597 if (auto *CRHS = dyn_cast<Constant>(Op1)) 598 return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL); 599 600 // Canonicalize the constant to the RHS if this is a commutative operation. 601 if (Instruction::isCommutative(Opcode)) 602 std::swap(Op0, Op1); 603 } 604 return nullptr; 605 } 606 607 /// Given operands for an Add, see if we can fold the result. 608 /// If not, this returns null. 609 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 610 const SimplifyQuery &Q, unsigned MaxRecurse) { 611 if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q)) 612 return C; 613 614 // X + undef -> undef 615 if (Q.isUndefValue(Op1)) 616 return Op1; 617 618 // X + 0 -> X 619 if (match(Op1, m_Zero())) 620 return Op0; 621 622 // If two operands are negative, return 0. 623 if (isKnownNegation(Op0, Op1)) 624 return Constant::getNullValue(Op0->getType()); 625 626 // X + (Y - X) -> Y 627 // (Y - X) + X -> Y 628 // Eg: X + -X -> 0 629 Value *Y = nullptr; 630 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 631 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 632 return Y; 633 634 // X + ~X -> -1 since ~X = -X-1 635 Type *Ty = Op0->getType(); 636 if (match(Op0, m_Not(m_Specific(Op1))) || 637 match(Op1, m_Not(m_Specific(Op0)))) 638 return Constant::getAllOnesValue(Ty); 639 640 // add nsw/nuw (xor Y, signmask), signmask --> Y 641 // The no-wrapping add guarantees that the top bit will be set by the add. 642 // Therefore, the xor must be clearing the already set sign bit of Y. 643 if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) && 644 match(Op0, m_Xor(m_Value(Y), m_SignMask()))) 645 return Y; 646 647 // add nuw %x, -1 -> -1, because %x can only be 0. 648 if (IsNUW && match(Op1, m_AllOnes())) 649 return Op1; // Which is -1. 650 651 /// i1 add -> xor. 652 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 653 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 654 return V; 655 656 // Try some generic simplifications for associative operations. 657 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, 658 MaxRecurse)) 659 return V; 660 661 // Threading Add over selects and phi nodes is pointless, so don't bother. 662 // Threading over the select in "A + select(cond, B, C)" means evaluating 663 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 664 // only if B and C are equal. If B and C are equal then (since we assume 665 // that operands have already been simplified) "select(cond, B, C)" should 666 // have been simplified to the common value of B and C already. Analysing 667 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 668 // for threading over phi nodes. 669 670 return nullptr; 671 } 672 673 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 674 const SimplifyQuery &Query) { 675 return ::SimplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit); 676 } 677 678 /// Compute the base pointer and cumulative constant offsets for V. 679 /// 680 /// This strips all constant offsets off of V, leaving it the base pointer, and 681 /// accumulates the total constant offset applied in the returned constant. It 682 /// returns 0 if V is not a pointer, and returns the constant '0' if there are 683 /// no constant offsets applied. 684 /// 685 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't 686 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc. 687 /// folding. 688 static Constant *stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V, 689 bool AllowNonInbounds = false) { 690 assert(V->getType()->isPtrOrPtrVectorTy()); 691 692 Type *IntIdxTy = DL.getIndexType(V->getType())->getScalarType(); 693 APInt Offset = APInt::getNullValue(IntIdxTy->getIntegerBitWidth()); 694 695 V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds); 696 // As that strip may trace through `addrspacecast`, need to sext or trunc 697 // the offset calculated. 698 IntIdxTy = DL.getIndexType(V->getType())->getScalarType(); 699 Offset = Offset.sextOrTrunc(IntIdxTy->getIntegerBitWidth()); 700 701 Constant *OffsetIntPtr = ConstantInt::get(IntIdxTy, Offset); 702 if (VectorType *VecTy = dyn_cast<VectorType>(V->getType())) 703 return ConstantVector::getSplat(VecTy->getElementCount(), OffsetIntPtr); 704 return OffsetIntPtr; 705 } 706 707 /// Compute the constant difference between two pointer values. 708 /// If the difference is not a constant, returns zero. 709 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS, 710 Value *RHS) { 711 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS); 712 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS); 713 714 // If LHS and RHS are not related via constant offsets to the same base 715 // value, there is nothing we can do here. 716 if (LHS != RHS) 717 return nullptr; 718 719 // Otherwise, the difference of LHS - RHS can be computed as: 720 // LHS - RHS 721 // = (LHSOffset + Base) - (RHSOffset + Base) 722 // = LHSOffset - RHSOffset 723 return ConstantExpr::getSub(LHSOffset, RHSOffset); 724 } 725 726 /// Given operands for a Sub, see if we can fold the result. 727 /// If not, this returns null. 728 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 729 const SimplifyQuery &Q, unsigned MaxRecurse) { 730 if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q)) 731 return C; 732 733 // X - undef -> undef 734 // undef - X -> undef 735 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 736 return UndefValue::get(Op0->getType()); 737 738 // X - 0 -> X 739 if (match(Op1, m_Zero())) 740 return Op0; 741 742 // X - X -> 0 743 if (Op0 == Op1) 744 return Constant::getNullValue(Op0->getType()); 745 746 // Is this a negation? 747 if (match(Op0, m_Zero())) { 748 // 0 - X -> 0 if the sub is NUW. 749 if (isNUW) 750 return Constant::getNullValue(Op0->getType()); 751 752 KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 753 if (Known.Zero.isMaxSignedValue()) { 754 // Op1 is either 0 or the minimum signed value. If the sub is NSW, then 755 // Op1 must be 0 because negating the minimum signed value is undefined. 756 if (isNSW) 757 return Constant::getNullValue(Op0->getType()); 758 759 // 0 - X -> X if X is 0 or the minimum signed value. 760 return Op1; 761 } 762 } 763 764 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 765 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 766 Value *X = nullptr, *Y = nullptr, *Z = Op1; 767 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 768 // See if "V === Y - Z" simplifies. 769 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1)) 770 // It does! Now see if "X + V" simplifies. 771 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) { 772 // It does, we successfully reassociated! 773 ++NumReassoc; 774 return W; 775 } 776 // See if "V === X - Z" simplifies. 777 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 778 // It does! Now see if "Y + V" simplifies. 779 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) { 780 // It does, we successfully reassociated! 781 ++NumReassoc; 782 return W; 783 } 784 } 785 786 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 787 // For example, X - (X + 1) -> -1 788 X = Op0; 789 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 790 // See if "V === X - Y" simplifies. 791 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 792 // It does! Now see if "V - Z" simplifies. 793 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) { 794 // It does, we successfully reassociated! 795 ++NumReassoc; 796 return W; 797 } 798 // See if "V === X - Z" simplifies. 799 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 800 // It does! Now see if "V - Y" simplifies. 801 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) { 802 // It does, we successfully reassociated! 803 ++NumReassoc; 804 return W; 805 } 806 } 807 808 // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 809 // For example, X - (X - Y) -> Y. 810 Z = Op0; 811 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 812 // See if "V === Z - X" simplifies. 813 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1)) 814 // It does! Now see if "V + Y" simplifies. 815 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) { 816 // It does, we successfully reassociated! 817 ++NumReassoc; 818 return W; 819 } 820 821 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. 822 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && 823 match(Op1, m_Trunc(m_Value(Y)))) 824 if (X->getType() == Y->getType()) 825 // See if "V === X - Y" simplifies. 826 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 827 // It does! Now see if "trunc V" simplifies. 828 if (Value *W = SimplifyCastInst(Instruction::Trunc, V, Op0->getType(), 829 Q, MaxRecurse - 1)) 830 // It does, return the simplified "trunc V". 831 return W; 832 833 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). 834 if (match(Op0, m_PtrToInt(m_Value(X))) && 835 match(Op1, m_PtrToInt(m_Value(Y)))) 836 if (Constant *Result = computePointerDifference(Q.DL, X, Y)) 837 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true); 838 839 // i1 sub -> xor. 840 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 841 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 842 return V; 843 844 // Threading Sub over selects and phi nodes is pointless, so don't bother. 845 // Threading over the select in "A - select(cond, B, C)" means evaluating 846 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 847 // only if B and C are equal. If B and C are equal then (since we assume 848 // that operands have already been simplified) "select(cond, B, C)" should 849 // have been simplified to the common value of B and C already. Analysing 850 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 851 // for threading over phi nodes. 852 853 return nullptr; 854 } 855 856 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 857 const SimplifyQuery &Q) { 858 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit); 859 } 860 861 /// Given operands for a Mul, see if we can fold the result. 862 /// If not, this returns null. 863 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 864 unsigned MaxRecurse) { 865 if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q)) 866 return C; 867 868 // X * undef -> 0 869 // X * 0 -> 0 870 if (Q.isUndefValue(Op1) || match(Op1, m_Zero())) 871 return Constant::getNullValue(Op0->getType()); 872 873 // X * 1 -> X 874 if (match(Op1, m_One())) 875 return Op0; 876 877 // (X / Y) * Y -> X if the division is exact. 878 Value *X = nullptr; 879 if (Q.IIQ.UseInstrInfo && 880 (match(Op0, 881 m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y 882 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))) // Y * (X / Y) 883 return X; 884 885 // i1 mul -> and. 886 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 887 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1)) 888 return V; 889 890 // Try some generic simplifications for associative operations. 891 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, 892 MaxRecurse)) 893 return V; 894 895 // Mul distributes over Add. Try some generic simplifications based on this. 896 if (Value *V = expandCommutativeBinOp(Instruction::Mul, Op0, Op1, 897 Instruction::Add, Q, MaxRecurse)) 898 return V; 899 900 // If the operation is with the result of a select instruction, check whether 901 // operating on either branch of the select always yields the same value. 902 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 903 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, 904 MaxRecurse)) 905 return V; 906 907 // If the operation is with the result of a phi instruction, check whether 908 // operating on all incoming values of the phi always yields the same value. 909 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 910 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, 911 MaxRecurse)) 912 return V; 913 914 return nullptr; 915 } 916 917 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 918 return ::SimplifyMulInst(Op0, Op1, Q, RecursionLimit); 919 } 920 921 /// Check for common or similar folds of integer division or integer remainder. 922 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem). 923 static Value *simplifyDivRem(Value *Op0, Value *Op1, bool IsDiv, 924 const SimplifyQuery &Q) { 925 Type *Ty = Op0->getType(); 926 927 // X / undef -> poison 928 // X % undef -> poison 929 if (Q.isUndefValue(Op1)) 930 return PoisonValue::get(Ty); 931 932 // X / 0 -> poison 933 // X % 0 -> poison 934 // We don't need to preserve faults! 935 if (match(Op1, m_Zero())) 936 return PoisonValue::get(Ty); 937 938 // If any element of a constant divisor fixed width vector is zero or undef 939 // the behavior is undefined and we can fold the whole op to poison. 940 auto *Op1C = dyn_cast<Constant>(Op1); 941 auto *VTy = dyn_cast<FixedVectorType>(Ty); 942 if (Op1C && VTy) { 943 unsigned NumElts = VTy->getNumElements(); 944 for (unsigned i = 0; i != NumElts; ++i) { 945 Constant *Elt = Op1C->getAggregateElement(i); 946 if (Elt && (Elt->isNullValue() || Q.isUndefValue(Elt))) 947 return PoisonValue::get(Ty); 948 } 949 } 950 951 // undef / X -> 0 952 // undef % X -> 0 953 if (Q.isUndefValue(Op0)) 954 return Constant::getNullValue(Ty); 955 956 // 0 / X -> 0 957 // 0 % X -> 0 958 if (match(Op0, m_Zero())) 959 return Constant::getNullValue(Op0->getType()); 960 961 // X / X -> 1 962 // X % X -> 0 963 if (Op0 == Op1) 964 return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty); 965 966 // X / 1 -> X 967 // X % 1 -> 0 968 // If this is a boolean op (single-bit element type), we can't have 969 // division-by-zero or remainder-by-zero, so assume the divisor is 1. 970 // Similarly, if we're zero-extending a boolean divisor, then assume it's a 1. 971 Value *X; 972 if (match(Op1, m_One()) || Ty->isIntOrIntVectorTy(1) || 973 (match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) 974 return IsDiv ? Op0 : Constant::getNullValue(Ty); 975 976 return nullptr; 977 } 978 979 /// Given a predicate and two operands, return true if the comparison is true. 980 /// This is a helper for div/rem simplification where we return some other value 981 /// when we can prove a relationship between the operands. 982 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS, 983 const SimplifyQuery &Q, unsigned MaxRecurse) { 984 Value *V = SimplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse); 985 Constant *C = dyn_cast_or_null<Constant>(V); 986 return (C && C->isAllOnesValue()); 987 } 988 989 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer 990 /// to simplify X % Y to X. 991 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q, 992 unsigned MaxRecurse, bool IsSigned) { 993 // Recursion is always used, so bail out at once if we already hit the limit. 994 if (!MaxRecurse--) 995 return false; 996 997 if (IsSigned) { 998 // |X| / |Y| --> 0 999 // 1000 // We require that 1 operand is a simple constant. That could be extended to 1001 // 2 variables if we computed the sign bit for each. 1002 // 1003 // Make sure that a constant is not the minimum signed value because taking 1004 // the abs() of that is undefined. 1005 Type *Ty = X->getType(); 1006 const APInt *C; 1007 if (match(X, m_APInt(C)) && !C->isMinSignedValue()) { 1008 // Is the variable divisor magnitude always greater than the constant 1009 // dividend magnitude? 1010 // |Y| > |C| --> Y < -abs(C) or Y > abs(C) 1011 Constant *PosDividendC = ConstantInt::get(Ty, C->abs()); 1012 Constant *NegDividendC = ConstantInt::get(Ty, -C->abs()); 1013 if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) || 1014 isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse)) 1015 return true; 1016 } 1017 if (match(Y, m_APInt(C))) { 1018 // Special-case: we can't take the abs() of a minimum signed value. If 1019 // that's the divisor, then all we have to do is prove that the dividend 1020 // is also not the minimum signed value. 1021 if (C->isMinSignedValue()) 1022 return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse); 1023 1024 // Is the variable dividend magnitude always less than the constant 1025 // divisor magnitude? 1026 // |X| < |C| --> X > -abs(C) and X < abs(C) 1027 Constant *PosDivisorC = ConstantInt::get(Ty, C->abs()); 1028 Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs()); 1029 if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) && 1030 isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse)) 1031 return true; 1032 } 1033 return false; 1034 } 1035 1036 // IsSigned == false. 1037 // Is the dividend unsigned less than the divisor? 1038 return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse); 1039 } 1040 1041 /// These are simplifications common to SDiv and UDiv. 1042 static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1043 const SimplifyQuery &Q, unsigned MaxRecurse) { 1044 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1045 return C; 1046 1047 if (Value *V = simplifyDivRem(Op0, Op1, true, Q)) 1048 return V; 1049 1050 bool IsSigned = Opcode == Instruction::SDiv; 1051 1052 // (X * Y) / Y -> X if the multiplication does not overflow. 1053 Value *X; 1054 if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) { 1055 auto *Mul = cast<OverflowingBinaryOperator>(Op0); 1056 // If the Mul does not overflow, then we are good to go. 1057 if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) || 1058 (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul))) 1059 return X; 1060 // If X has the form X = A / Y, then X * Y cannot overflow. 1061 if ((IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) || 1062 (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) 1063 return X; 1064 } 1065 1066 // (X rem Y) / Y -> 0 1067 if ((IsSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || 1068 (!IsSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1))))) 1069 return Constant::getNullValue(Op0->getType()); 1070 1071 // (X /u C1) /u C2 -> 0 if C1 * C2 overflow 1072 ConstantInt *C1, *C2; 1073 if (!IsSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) && 1074 match(Op1, m_ConstantInt(C2))) { 1075 bool Overflow; 1076 (void)C1->getValue().umul_ov(C2->getValue(), Overflow); 1077 if (Overflow) 1078 return Constant::getNullValue(Op0->getType()); 1079 } 1080 1081 // If the operation is with the result of a select instruction, check whether 1082 // operating on either branch of the select always yields the same value. 1083 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1084 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1085 return V; 1086 1087 // If the operation is with the result of a phi instruction, check whether 1088 // operating on all incoming values of the phi always yields the same value. 1089 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1090 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1091 return V; 1092 1093 if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned)) 1094 return Constant::getNullValue(Op0->getType()); 1095 1096 return nullptr; 1097 } 1098 1099 /// These are simplifications common to SRem and URem. 1100 static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1101 const SimplifyQuery &Q, unsigned MaxRecurse) { 1102 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1103 return C; 1104 1105 if (Value *V = simplifyDivRem(Op0, Op1, false, Q)) 1106 return V; 1107 1108 // (X % Y) % Y -> X % Y 1109 if ((Opcode == Instruction::SRem && 1110 match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || 1111 (Opcode == Instruction::URem && 1112 match(Op0, m_URem(m_Value(), m_Specific(Op1))))) 1113 return Op0; 1114 1115 // (X << Y) % X -> 0 1116 if (Q.IIQ.UseInstrInfo && 1117 ((Opcode == Instruction::SRem && 1118 match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) || 1119 (Opcode == Instruction::URem && 1120 match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))) 1121 return Constant::getNullValue(Op0->getType()); 1122 1123 // If the operation is with the result of a select instruction, check whether 1124 // operating on either branch of the select always yields the same value. 1125 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1126 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1127 return V; 1128 1129 // If the operation is with the result of a phi instruction, check whether 1130 // operating on all incoming values of the phi always yields the same value. 1131 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1132 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1133 return V; 1134 1135 // If X / Y == 0, then X % Y == X. 1136 if (isDivZero(Op0, Op1, Q, MaxRecurse, Opcode == Instruction::SRem)) 1137 return Op0; 1138 1139 return nullptr; 1140 } 1141 1142 /// Given operands for an SDiv, see if we can fold the result. 1143 /// If not, this returns null. 1144 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1145 unsigned MaxRecurse) { 1146 // If two operands are negated and no signed overflow, return -1. 1147 if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true)) 1148 return Constant::getAllOnesValue(Op0->getType()); 1149 1150 return simplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse); 1151 } 1152 1153 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1154 return ::SimplifySDivInst(Op0, Op1, Q, RecursionLimit); 1155 } 1156 1157 /// Given operands for a UDiv, see if we can fold the result. 1158 /// If not, this returns null. 1159 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1160 unsigned MaxRecurse) { 1161 return simplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse); 1162 } 1163 1164 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1165 return ::SimplifyUDivInst(Op0, Op1, Q, RecursionLimit); 1166 } 1167 1168 /// Given operands for an SRem, see if we can fold the result. 1169 /// If not, this returns null. 1170 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1171 unsigned MaxRecurse) { 1172 // If the divisor is 0, the result is undefined, so assume the divisor is -1. 1173 // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0 1174 Value *X; 1175 if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) 1176 return ConstantInt::getNullValue(Op0->getType()); 1177 1178 // If the two operands are negated, return 0. 1179 if (isKnownNegation(Op0, Op1)) 1180 return ConstantInt::getNullValue(Op0->getType()); 1181 1182 return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse); 1183 } 1184 1185 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1186 return ::SimplifySRemInst(Op0, Op1, Q, RecursionLimit); 1187 } 1188 1189 /// Given operands for a URem, see if we can fold the result. 1190 /// If not, this returns null. 1191 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1192 unsigned MaxRecurse) { 1193 return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse); 1194 } 1195 1196 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1197 return ::SimplifyURemInst(Op0, Op1, Q, RecursionLimit); 1198 } 1199 1200 /// Returns true if a shift by \c Amount always yields poison. 1201 static bool isPoisonShift(Value *Amount, const SimplifyQuery &Q) { 1202 Constant *C = dyn_cast<Constant>(Amount); 1203 if (!C) 1204 return false; 1205 1206 // X shift by undef -> poison because it may shift by the bitwidth. 1207 if (Q.isUndefValue(C)) 1208 return true; 1209 1210 // Shifting by the bitwidth or more is undefined. 1211 if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) 1212 if (CI->getValue().uge(CI->getType()->getScalarSizeInBits())) 1213 return true; 1214 1215 // If all lanes of a vector shift are undefined the whole shift is. 1216 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) { 1217 for (unsigned I = 0, 1218 E = cast<FixedVectorType>(C->getType())->getNumElements(); 1219 I != E; ++I) 1220 if (!isPoisonShift(C->getAggregateElement(I), Q)) 1221 return false; 1222 return true; 1223 } 1224 1225 return false; 1226 } 1227 1228 /// Given operands for an Shl, LShr or AShr, see if we can fold the result. 1229 /// If not, this returns null. 1230 static Value *SimplifyShift(Instruction::BinaryOps Opcode, Value *Op0, 1231 Value *Op1, bool IsNSW, const SimplifyQuery &Q, 1232 unsigned MaxRecurse) { 1233 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1234 return C; 1235 1236 // 0 shift by X -> 0 1237 if (match(Op0, m_Zero())) 1238 return Constant::getNullValue(Op0->getType()); 1239 1240 // X shift by 0 -> X 1241 // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones 1242 // would be poison. 1243 Value *X; 1244 if (match(Op1, m_Zero()) || 1245 (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) 1246 return Op0; 1247 1248 // Fold undefined shifts. 1249 if (isPoisonShift(Op1, Q)) 1250 return PoisonValue::get(Op0->getType()); 1251 1252 // If the operation is with the result of a select instruction, check whether 1253 // operating on either branch of the select always yields the same value. 1254 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1255 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1256 return V; 1257 1258 // If the operation is with the result of a phi instruction, check whether 1259 // operating on all incoming values of the phi always yields the same value. 1260 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1261 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1262 return V; 1263 1264 // If any bits in the shift amount make that value greater than or equal to 1265 // the number of bits in the type, the shift is undefined. 1266 KnownBits KnownAmt = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1267 if (KnownAmt.getMinValue().uge(KnownAmt.getBitWidth())) 1268 return PoisonValue::get(Op0->getType()); 1269 1270 // If all valid bits in the shift amount are known zero, the first operand is 1271 // unchanged. 1272 unsigned NumValidShiftBits = Log2_32_Ceil(KnownAmt.getBitWidth()); 1273 if (KnownAmt.countMinTrailingZeros() >= NumValidShiftBits) 1274 return Op0; 1275 1276 // Check for nsw shl leading to a poison value. 1277 if (IsNSW) { 1278 assert(Opcode == Instruction::Shl && "Expected shl for nsw instruction"); 1279 KnownBits KnownVal = computeKnownBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1280 KnownBits KnownShl = KnownBits::shl(KnownVal, KnownAmt); 1281 1282 if (KnownVal.Zero.isSignBitSet()) 1283 KnownShl.Zero.setSignBit(); 1284 if (KnownVal.One.isSignBitSet()) 1285 KnownShl.One.setSignBit(); 1286 1287 if (KnownShl.hasConflict()) 1288 return PoisonValue::get(Op0->getType()); 1289 } 1290 1291 return nullptr; 1292 } 1293 1294 /// Given operands for an Shl, LShr or AShr, see if we can 1295 /// fold the result. If not, this returns null. 1296 static Value *SimplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0, 1297 Value *Op1, bool isExact, const SimplifyQuery &Q, 1298 unsigned MaxRecurse) { 1299 if (Value *V = 1300 SimplifyShift(Opcode, Op0, Op1, /*IsNSW*/ false, Q, MaxRecurse)) 1301 return V; 1302 1303 // X >> X -> 0 1304 if (Op0 == Op1) 1305 return Constant::getNullValue(Op0->getType()); 1306 1307 // undef >> X -> 0 1308 // undef >> X -> undef (if it's exact) 1309 if (Q.isUndefValue(Op0)) 1310 return isExact ? Op0 : Constant::getNullValue(Op0->getType()); 1311 1312 // The low bit cannot be shifted out of an exact shift if it is set. 1313 if (isExact) { 1314 KnownBits Op0Known = computeKnownBits(Op0, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT); 1315 if (Op0Known.One[0]) 1316 return Op0; 1317 } 1318 1319 return nullptr; 1320 } 1321 1322 /// Given operands for an Shl, see if we can fold the result. 1323 /// If not, this returns null. 1324 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1325 const SimplifyQuery &Q, unsigned MaxRecurse) { 1326 if (Value *V = 1327 SimplifyShift(Instruction::Shl, Op0, Op1, isNSW, Q, MaxRecurse)) 1328 return V; 1329 1330 // undef << X -> 0 1331 // undef << X -> undef if (if it's NSW/NUW) 1332 if (Q.isUndefValue(Op0)) 1333 return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType()); 1334 1335 // (X >> A) << A -> X 1336 Value *X; 1337 if (Q.IIQ.UseInstrInfo && 1338 match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) 1339 return X; 1340 1341 // shl nuw i8 C, %x -> C iff C has sign bit set. 1342 if (isNUW && match(Op0, m_Negative())) 1343 return Op0; 1344 // NOTE: could use computeKnownBits() / LazyValueInfo, 1345 // but the cost-benefit analysis suggests it isn't worth it. 1346 1347 return nullptr; 1348 } 1349 1350 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1351 const SimplifyQuery &Q) { 1352 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit); 1353 } 1354 1355 /// Given operands for an LShr, see if we can fold the result. 1356 /// If not, this returns null. 1357 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1358 const SimplifyQuery &Q, unsigned MaxRecurse) { 1359 if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q, 1360 MaxRecurse)) 1361 return V; 1362 1363 // (X << A) >> A -> X 1364 Value *X; 1365 if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1)))) 1366 return X; 1367 1368 // ((X << A) | Y) >> A -> X if effective width of Y is not larger than A. 1369 // We can return X as we do in the above case since OR alters no bits in X. 1370 // SimplifyDemandedBits in InstCombine can do more general optimization for 1371 // bit manipulation. This pattern aims to provide opportunities for other 1372 // optimizers by supporting a simple but common case in InstSimplify. 1373 Value *Y; 1374 const APInt *ShRAmt, *ShLAmt; 1375 if (match(Op1, m_APInt(ShRAmt)) && 1376 match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) && 1377 *ShRAmt == *ShLAmt) { 1378 const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1379 const unsigned Width = Op0->getType()->getScalarSizeInBits(); 1380 const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros(); 1381 if (ShRAmt->uge(EffWidthY)) 1382 return X; 1383 } 1384 1385 return nullptr; 1386 } 1387 1388 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1389 const SimplifyQuery &Q) { 1390 return ::SimplifyLShrInst(Op0, Op1, isExact, Q, RecursionLimit); 1391 } 1392 1393 /// Given operands for an AShr, see if we can fold the result. 1394 /// If not, this returns null. 1395 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1396 const SimplifyQuery &Q, unsigned MaxRecurse) { 1397 if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q, 1398 MaxRecurse)) 1399 return V; 1400 1401 // all ones >>a X -> -1 1402 // Do not return Op0 because it may contain undef elements if it's a vector. 1403 if (match(Op0, m_AllOnes())) 1404 return Constant::getAllOnesValue(Op0->getType()); 1405 1406 // (X << A) >> A -> X 1407 Value *X; 1408 if (Q.IIQ.UseInstrInfo && match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1)))) 1409 return X; 1410 1411 // Arithmetic shifting an all-sign-bit value is a no-op. 1412 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1413 if (NumSignBits == Op0->getType()->getScalarSizeInBits()) 1414 return Op0; 1415 1416 return nullptr; 1417 } 1418 1419 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1420 const SimplifyQuery &Q) { 1421 return ::SimplifyAShrInst(Op0, Op1, isExact, Q, RecursionLimit); 1422 } 1423 1424 /// Commuted variants are assumed to be handled by calling this function again 1425 /// with the parameters swapped. 1426 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp, 1427 ICmpInst *UnsignedICmp, bool IsAnd, 1428 const SimplifyQuery &Q) { 1429 Value *X, *Y; 1430 1431 ICmpInst::Predicate EqPred; 1432 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) || 1433 !ICmpInst::isEquality(EqPred)) 1434 return nullptr; 1435 1436 ICmpInst::Predicate UnsignedPred; 1437 1438 Value *A, *B; 1439 // Y = (A - B); 1440 if (match(Y, m_Sub(m_Value(A), m_Value(B)))) { 1441 if (match(UnsignedICmp, 1442 m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) && 1443 ICmpInst::isUnsigned(UnsignedPred)) { 1444 // A >=/<= B || (A - B) != 0 <--> true 1445 if ((UnsignedPred == ICmpInst::ICMP_UGE || 1446 UnsignedPred == ICmpInst::ICMP_ULE) && 1447 EqPred == ICmpInst::ICMP_NE && !IsAnd) 1448 return ConstantInt::getTrue(UnsignedICmp->getType()); 1449 // A </> B && (A - B) == 0 <--> false 1450 if ((UnsignedPred == ICmpInst::ICMP_ULT || 1451 UnsignedPred == ICmpInst::ICMP_UGT) && 1452 EqPred == ICmpInst::ICMP_EQ && IsAnd) 1453 return ConstantInt::getFalse(UnsignedICmp->getType()); 1454 1455 // A </> B && (A - B) != 0 <--> A </> B 1456 // A </> B || (A - B) != 0 <--> (A - B) != 0 1457 if (EqPred == ICmpInst::ICMP_NE && (UnsignedPred == ICmpInst::ICMP_ULT || 1458 UnsignedPred == ICmpInst::ICMP_UGT)) 1459 return IsAnd ? UnsignedICmp : ZeroICmp; 1460 1461 // A <=/>= B && (A - B) == 0 <--> (A - B) == 0 1462 // A <=/>= B || (A - B) == 0 <--> A <=/>= B 1463 if (EqPred == ICmpInst::ICMP_EQ && (UnsignedPred == ICmpInst::ICMP_ULE || 1464 UnsignedPred == ICmpInst::ICMP_UGE)) 1465 return IsAnd ? ZeroICmp : UnsignedICmp; 1466 } 1467 1468 // Given Y = (A - B) 1469 // Y >= A && Y != 0 --> Y >= A iff B != 0 1470 // Y < A || Y == 0 --> Y < A iff B != 0 1471 if (match(UnsignedICmp, 1472 m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) { 1473 if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd && 1474 EqPred == ICmpInst::ICMP_NE && 1475 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1476 return UnsignedICmp; 1477 if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd && 1478 EqPred == ICmpInst::ICMP_EQ && 1479 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1480 return UnsignedICmp; 1481 } 1482 } 1483 1484 if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) && 1485 ICmpInst::isUnsigned(UnsignedPred)) 1486 ; 1487 else if (match(UnsignedICmp, 1488 m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) && 1489 ICmpInst::isUnsigned(UnsignedPred)) 1490 UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); 1491 else 1492 return nullptr; 1493 1494 // X > Y && Y == 0 --> Y == 0 iff X != 0 1495 // X > Y || Y == 0 --> X > Y iff X != 0 1496 if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ && 1497 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1498 return IsAnd ? ZeroICmp : UnsignedICmp; 1499 1500 // X <= Y && Y != 0 --> X <= Y iff X != 0 1501 // X <= Y || Y != 0 --> Y != 0 iff X != 0 1502 if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE && 1503 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1504 return IsAnd ? UnsignedICmp : ZeroICmp; 1505 1506 // The transforms below here are expected to be handled more generally with 1507 // simplifyAndOrOfICmpsWithLimitConst() or in InstCombine's 1508 // foldAndOrOfICmpsWithConstEq(). If we are looking to trim optimizer overlap, 1509 // these are candidates for removal. 1510 1511 // X < Y && Y != 0 --> X < Y 1512 // X < Y || Y != 0 --> Y != 0 1513 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE) 1514 return IsAnd ? UnsignedICmp : ZeroICmp; 1515 1516 // X >= Y && Y == 0 --> Y == 0 1517 // X >= Y || Y == 0 --> X >= Y 1518 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ) 1519 return IsAnd ? ZeroICmp : UnsignedICmp; 1520 1521 // X < Y && Y == 0 --> false 1522 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ && 1523 IsAnd) 1524 return getFalse(UnsignedICmp->getType()); 1525 1526 // X >= Y || Y != 0 --> true 1527 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE && 1528 !IsAnd) 1529 return getTrue(UnsignedICmp->getType()); 1530 1531 return nullptr; 1532 } 1533 1534 /// Commuted variants are assumed to be handled by calling this function again 1535 /// with the parameters swapped. 1536 static Value *simplifyAndOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) { 1537 ICmpInst::Predicate Pred0, Pred1; 1538 Value *A ,*B; 1539 if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) || 1540 !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B)))) 1541 return nullptr; 1542 1543 // We have (icmp Pred0, A, B) & (icmp Pred1, A, B). 1544 // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we 1545 // can eliminate Op1 from this 'and'. 1546 if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1)) 1547 return Op0; 1548 1549 // Check for any combination of predicates that are guaranteed to be disjoint. 1550 if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) || 1551 (Pred0 == ICmpInst::ICMP_EQ && ICmpInst::isFalseWhenEqual(Pred1)) || 1552 (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT) || 1553 (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)) 1554 return getFalse(Op0->getType()); 1555 1556 return nullptr; 1557 } 1558 1559 /// Commuted variants are assumed to be handled by calling this function again 1560 /// with the parameters swapped. 1561 static Value *simplifyOrOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) { 1562 ICmpInst::Predicate Pred0, Pred1; 1563 Value *A ,*B; 1564 if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) || 1565 !match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B)))) 1566 return nullptr; 1567 1568 // We have (icmp Pred0, A, B) | (icmp Pred1, A, B). 1569 // If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we 1570 // can eliminate Op0 from this 'or'. 1571 if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1)) 1572 return Op1; 1573 1574 // Check for any combination of predicates that cover the entire range of 1575 // possibilities. 1576 if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) || 1577 (Pred0 == ICmpInst::ICMP_NE && ICmpInst::isTrueWhenEqual(Pred1)) || 1578 (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGE) || 1579 (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE)) 1580 return getTrue(Op0->getType()); 1581 1582 return nullptr; 1583 } 1584 1585 /// Test if a pair of compares with a shared operand and 2 constants has an 1586 /// empty set intersection, full set union, or if one compare is a superset of 1587 /// the other. 1588 static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1, 1589 bool IsAnd) { 1590 // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)). 1591 if (Cmp0->getOperand(0) != Cmp1->getOperand(0)) 1592 return nullptr; 1593 1594 const APInt *C0, *C1; 1595 if (!match(Cmp0->getOperand(1), m_APInt(C0)) || 1596 !match(Cmp1->getOperand(1), m_APInt(C1))) 1597 return nullptr; 1598 1599 auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0); 1600 auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1); 1601 1602 // For and-of-compares, check if the intersection is empty: 1603 // (icmp X, C0) && (icmp X, C1) --> empty set --> false 1604 if (IsAnd && Range0.intersectWith(Range1).isEmptySet()) 1605 return getFalse(Cmp0->getType()); 1606 1607 // For or-of-compares, check if the union is full: 1608 // (icmp X, C0) || (icmp X, C1) --> full set --> true 1609 if (!IsAnd && Range0.unionWith(Range1).isFullSet()) 1610 return getTrue(Cmp0->getType()); 1611 1612 // Is one range a superset of the other? 1613 // If this is and-of-compares, take the smaller set: 1614 // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42 1615 // If this is or-of-compares, take the larger set: 1616 // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4 1617 if (Range0.contains(Range1)) 1618 return IsAnd ? Cmp1 : Cmp0; 1619 if (Range1.contains(Range0)) 1620 return IsAnd ? Cmp0 : Cmp1; 1621 1622 return nullptr; 1623 } 1624 1625 static Value *simplifyAndOrOfICmpsWithZero(ICmpInst *Cmp0, ICmpInst *Cmp1, 1626 bool IsAnd) { 1627 ICmpInst::Predicate P0 = Cmp0->getPredicate(), P1 = Cmp1->getPredicate(); 1628 if (!match(Cmp0->getOperand(1), m_Zero()) || 1629 !match(Cmp1->getOperand(1), m_Zero()) || P0 != P1) 1630 return nullptr; 1631 1632 if ((IsAnd && P0 != ICmpInst::ICMP_NE) || (!IsAnd && P1 != ICmpInst::ICMP_EQ)) 1633 return nullptr; 1634 1635 // We have either "(X == 0 || Y == 0)" or "(X != 0 && Y != 0)". 1636 Value *X = Cmp0->getOperand(0); 1637 Value *Y = Cmp1->getOperand(0); 1638 1639 // If one of the compares is a masked version of a (not) null check, then 1640 // that compare implies the other, so we eliminate the other. Optionally, look 1641 // through a pointer-to-int cast to match a null check of a pointer type. 1642 1643 // (X == 0) || (([ptrtoint] X & ?) == 0) --> ([ptrtoint] X & ?) == 0 1644 // (X == 0) || ((? & [ptrtoint] X) == 0) --> (? & [ptrtoint] X) == 0 1645 // (X != 0) && (([ptrtoint] X & ?) != 0) --> ([ptrtoint] X & ?) != 0 1646 // (X != 0) && ((? & [ptrtoint] X) != 0) --> (? & [ptrtoint] X) != 0 1647 if (match(Y, m_c_And(m_Specific(X), m_Value())) || 1648 match(Y, m_c_And(m_PtrToInt(m_Specific(X)), m_Value()))) 1649 return Cmp1; 1650 1651 // (([ptrtoint] Y & ?) == 0) || (Y == 0) --> ([ptrtoint] Y & ?) == 0 1652 // ((? & [ptrtoint] Y) == 0) || (Y == 0) --> (? & [ptrtoint] Y) == 0 1653 // (([ptrtoint] Y & ?) != 0) && (Y != 0) --> ([ptrtoint] Y & ?) != 0 1654 // ((? & [ptrtoint] Y) != 0) && (Y != 0) --> (? & [ptrtoint] Y) != 0 1655 if (match(X, m_c_And(m_Specific(Y), m_Value())) || 1656 match(X, m_c_And(m_PtrToInt(m_Specific(Y)), m_Value()))) 1657 return Cmp0; 1658 1659 return nullptr; 1660 } 1661 1662 static Value *simplifyAndOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1663 const InstrInfoQuery &IIQ) { 1664 // (icmp (add V, C0), C1) & (icmp V, C0) 1665 ICmpInst::Predicate Pred0, Pred1; 1666 const APInt *C0, *C1; 1667 Value *V; 1668 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1669 return nullptr; 1670 1671 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1672 return nullptr; 1673 1674 auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0)); 1675 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1676 return nullptr; 1677 1678 Type *ITy = Op0->getType(); 1679 bool isNSW = IIQ.hasNoSignedWrap(AddInst); 1680 bool isNUW = IIQ.hasNoUnsignedWrap(AddInst); 1681 1682 const APInt Delta = *C1 - *C0; 1683 if (C0->isStrictlyPositive()) { 1684 if (Delta == 2) { 1685 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT) 1686 return getFalse(ITy); 1687 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW) 1688 return getFalse(ITy); 1689 } 1690 if (Delta == 1) { 1691 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT) 1692 return getFalse(ITy); 1693 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW) 1694 return getFalse(ITy); 1695 } 1696 } 1697 if (C0->getBoolValue() && isNUW) { 1698 if (Delta == 2) 1699 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT) 1700 return getFalse(ITy); 1701 if (Delta == 1) 1702 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT) 1703 return getFalse(ITy); 1704 } 1705 1706 return nullptr; 1707 } 1708 1709 /// Try to eliminate compares with signed or unsigned min/max constants. 1710 static Value *simplifyAndOrOfICmpsWithLimitConst(ICmpInst *Cmp0, ICmpInst *Cmp1, 1711 bool IsAnd) { 1712 // Canonicalize an equality compare as Cmp0. 1713 if (Cmp1->isEquality()) 1714 std::swap(Cmp0, Cmp1); 1715 if (!Cmp0->isEquality()) 1716 return nullptr; 1717 1718 // The non-equality compare must include a common operand (X). Canonicalize 1719 // the common operand as operand 0 (the predicate is swapped if the common 1720 // operand was operand 1). 1721 ICmpInst::Predicate Pred0 = Cmp0->getPredicate(); 1722 Value *X = Cmp0->getOperand(0); 1723 ICmpInst::Predicate Pred1; 1724 bool HasNotOp = match(Cmp1, m_c_ICmp(Pred1, m_Not(m_Specific(X)), m_Value())); 1725 if (!HasNotOp && !match(Cmp1, m_c_ICmp(Pred1, m_Specific(X), m_Value()))) 1726 return nullptr; 1727 if (ICmpInst::isEquality(Pred1)) 1728 return nullptr; 1729 1730 // The equality compare must be against a constant. Flip bits if we matched 1731 // a bitwise not. Convert a null pointer constant to an integer zero value. 1732 APInt MinMaxC; 1733 const APInt *C; 1734 if (match(Cmp0->getOperand(1), m_APInt(C))) 1735 MinMaxC = HasNotOp ? ~*C : *C; 1736 else if (isa<ConstantPointerNull>(Cmp0->getOperand(1))) 1737 MinMaxC = APInt::getNullValue(8); 1738 else 1739 return nullptr; 1740 1741 // DeMorganize if this is 'or': P0 || P1 --> !P0 && !P1. 1742 if (!IsAnd) { 1743 Pred0 = ICmpInst::getInversePredicate(Pred0); 1744 Pred1 = ICmpInst::getInversePredicate(Pred1); 1745 } 1746 1747 // Normalize to unsigned compare and unsigned min/max value. 1748 // Example for 8-bit: -128 + 128 -> 0; 127 + 128 -> 255 1749 if (ICmpInst::isSigned(Pred1)) { 1750 Pred1 = ICmpInst::getUnsignedPredicate(Pred1); 1751 MinMaxC += APInt::getSignedMinValue(MinMaxC.getBitWidth()); 1752 } 1753 1754 // (X != MAX) && (X < Y) --> X < Y 1755 // (X == MAX) || (X >= Y) --> X >= Y 1756 if (MinMaxC.isMaxValue()) 1757 if (Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_ULT) 1758 return Cmp1; 1759 1760 // (X != MIN) && (X > Y) --> X > Y 1761 // (X == MIN) || (X <= Y) --> X <= Y 1762 if (MinMaxC.isMinValue()) 1763 if (Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_UGT) 1764 return Cmp1; 1765 1766 return nullptr; 1767 } 1768 1769 static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1770 const SimplifyQuery &Q) { 1771 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true, Q)) 1772 return X; 1773 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true, Q)) 1774 return X; 1775 1776 if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1)) 1777 return X; 1778 if (Value *X = simplifyAndOfICmpsWithSameOperands(Op1, Op0)) 1779 return X; 1780 1781 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true)) 1782 return X; 1783 1784 if (Value *X = simplifyAndOrOfICmpsWithLimitConst(Op0, Op1, true)) 1785 return X; 1786 1787 if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, true)) 1788 return X; 1789 1790 if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1791 return X; 1792 if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1793 return X; 1794 1795 return nullptr; 1796 } 1797 1798 static Value *simplifyOrOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1799 const InstrInfoQuery &IIQ) { 1800 // (icmp (add V, C0), C1) | (icmp V, C0) 1801 ICmpInst::Predicate Pred0, Pred1; 1802 const APInt *C0, *C1; 1803 Value *V; 1804 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1805 return nullptr; 1806 1807 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1808 return nullptr; 1809 1810 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0)); 1811 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1812 return nullptr; 1813 1814 Type *ITy = Op0->getType(); 1815 bool isNSW = IIQ.hasNoSignedWrap(AddInst); 1816 bool isNUW = IIQ.hasNoUnsignedWrap(AddInst); 1817 1818 const APInt Delta = *C1 - *C0; 1819 if (C0->isStrictlyPositive()) { 1820 if (Delta == 2) { 1821 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE) 1822 return getTrue(ITy); 1823 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW) 1824 return getTrue(ITy); 1825 } 1826 if (Delta == 1) { 1827 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE) 1828 return getTrue(ITy); 1829 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW) 1830 return getTrue(ITy); 1831 } 1832 } 1833 if (C0->getBoolValue() && isNUW) { 1834 if (Delta == 2) 1835 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE) 1836 return getTrue(ITy); 1837 if (Delta == 1) 1838 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE) 1839 return getTrue(ITy); 1840 } 1841 1842 return nullptr; 1843 } 1844 1845 static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1846 const SimplifyQuery &Q) { 1847 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false, Q)) 1848 return X; 1849 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false, Q)) 1850 return X; 1851 1852 if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1)) 1853 return X; 1854 if (Value *X = simplifyOrOfICmpsWithSameOperands(Op1, Op0)) 1855 return X; 1856 1857 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false)) 1858 return X; 1859 1860 if (Value *X = simplifyAndOrOfICmpsWithLimitConst(Op0, Op1, false)) 1861 return X; 1862 1863 if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, false)) 1864 return X; 1865 1866 if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1867 return X; 1868 if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1869 return X; 1870 1871 return nullptr; 1872 } 1873 1874 static Value *simplifyAndOrOfFCmps(const TargetLibraryInfo *TLI, 1875 FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) { 1876 Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); 1877 Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); 1878 if (LHS0->getType() != RHS0->getType()) 1879 return nullptr; 1880 1881 FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); 1882 if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) || 1883 (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) { 1884 // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y 1885 // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X 1886 // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y 1887 // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X 1888 // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y 1889 // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X 1890 // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y 1891 // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X 1892 if ((isKnownNeverNaN(LHS0, TLI) && (LHS1 == RHS0 || LHS1 == RHS1)) || 1893 (isKnownNeverNaN(LHS1, TLI) && (LHS0 == RHS0 || LHS0 == RHS1))) 1894 return RHS; 1895 1896 // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y 1897 // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X 1898 // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y 1899 // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X 1900 // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y 1901 // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X 1902 // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y 1903 // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X 1904 if ((isKnownNeverNaN(RHS0, TLI) && (RHS1 == LHS0 || RHS1 == LHS1)) || 1905 (isKnownNeverNaN(RHS1, TLI) && (RHS0 == LHS0 || RHS0 == LHS1))) 1906 return LHS; 1907 } 1908 1909 return nullptr; 1910 } 1911 1912 static Value *simplifyAndOrOfCmps(const SimplifyQuery &Q, 1913 Value *Op0, Value *Op1, bool IsAnd) { 1914 // Look through casts of the 'and' operands to find compares. 1915 auto *Cast0 = dyn_cast<CastInst>(Op0); 1916 auto *Cast1 = dyn_cast<CastInst>(Op1); 1917 if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() && 1918 Cast0->getSrcTy() == Cast1->getSrcTy()) { 1919 Op0 = Cast0->getOperand(0); 1920 Op1 = Cast1->getOperand(0); 1921 } 1922 1923 Value *V = nullptr; 1924 auto *ICmp0 = dyn_cast<ICmpInst>(Op0); 1925 auto *ICmp1 = dyn_cast<ICmpInst>(Op1); 1926 if (ICmp0 && ICmp1) 1927 V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q) 1928 : simplifyOrOfICmps(ICmp0, ICmp1, Q); 1929 1930 auto *FCmp0 = dyn_cast<FCmpInst>(Op0); 1931 auto *FCmp1 = dyn_cast<FCmpInst>(Op1); 1932 if (FCmp0 && FCmp1) 1933 V = simplifyAndOrOfFCmps(Q.TLI, FCmp0, FCmp1, IsAnd); 1934 1935 if (!V) 1936 return nullptr; 1937 if (!Cast0) 1938 return V; 1939 1940 // If we looked through casts, we can only handle a constant simplification 1941 // because we are not allowed to create a cast instruction here. 1942 if (auto *C = dyn_cast<Constant>(V)) 1943 return ConstantExpr::getCast(Cast0->getOpcode(), C, Cast0->getType()); 1944 1945 return nullptr; 1946 } 1947 1948 /// Check that the Op1 is in expected form, i.e.: 1949 /// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???) 1950 /// %Op1 = extractvalue { i4, i1 } %Agg, 1 1951 static bool omitCheckForZeroBeforeMulWithOverflowInternal(Value *Op1, 1952 Value *X) { 1953 auto *Extract = dyn_cast<ExtractValueInst>(Op1); 1954 // We should only be extracting the overflow bit. 1955 if (!Extract || !Extract->getIndices().equals(1)) 1956 return false; 1957 Value *Agg = Extract->getAggregateOperand(); 1958 // This should be a multiplication-with-overflow intrinsic. 1959 if (!match(Agg, m_CombineOr(m_Intrinsic<Intrinsic::umul_with_overflow>(), 1960 m_Intrinsic<Intrinsic::smul_with_overflow>()))) 1961 return false; 1962 // One of its multipliers should be the value we checked for zero before. 1963 if (!match(Agg, m_CombineOr(m_Argument<0>(m_Specific(X)), 1964 m_Argument<1>(m_Specific(X))))) 1965 return false; 1966 return true; 1967 } 1968 1969 /// The @llvm.[us]mul.with.overflow intrinsic could have been folded from some 1970 /// other form of check, e.g. one that was using division; it may have been 1971 /// guarded against division-by-zero. We can drop that check now. 1972 /// Look for: 1973 /// %Op0 = icmp ne i4 %X, 0 1974 /// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???) 1975 /// %Op1 = extractvalue { i4, i1 } %Agg, 1 1976 /// %??? = and i1 %Op0, %Op1 1977 /// We can just return %Op1 1978 static Value *omitCheckForZeroBeforeMulWithOverflow(Value *Op0, Value *Op1) { 1979 ICmpInst::Predicate Pred; 1980 Value *X; 1981 if (!match(Op0, m_ICmp(Pred, m_Value(X), m_Zero())) || 1982 Pred != ICmpInst::Predicate::ICMP_NE) 1983 return nullptr; 1984 // Is Op1 in expected form? 1985 if (!omitCheckForZeroBeforeMulWithOverflowInternal(Op1, X)) 1986 return nullptr; 1987 // Can omit 'and', and just return the overflow bit. 1988 return Op1; 1989 } 1990 1991 /// The @llvm.[us]mul.with.overflow intrinsic could have been folded from some 1992 /// other form of check, e.g. one that was using division; it may have been 1993 /// guarded against division-by-zero. We can drop that check now. 1994 /// Look for: 1995 /// %Op0 = icmp eq i4 %X, 0 1996 /// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???) 1997 /// %Op1 = extractvalue { i4, i1 } %Agg, 1 1998 /// %NotOp1 = xor i1 %Op1, true 1999 /// %or = or i1 %Op0, %NotOp1 2000 /// We can just return %NotOp1 2001 static Value *omitCheckForZeroBeforeInvertedMulWithOverflow(Value *Op0, 2002 Value *NotOp1) { 2003 ICmpInst::Predicate Pred; 2004 Value *X; 2005 if (!match(Op0, m_ICmp(Pred, m_Value(X), m_Zero())) || 2006 Pred != ICmpInst::Predicate::ICMP_EQ) 2007 return nullptr; 2008 // We expect the other hand of an 'or' to be a 'not'. 2009 Value *Op1; 2010 if (!match(NotOp1, m_Not(m_Value(Op1)))) 2011 return nullptr; 2012 // Is Op1 in expected form? 2013 if (!omitCheckForZeroBeforeMulWithOverflowInternal(Op1, X)) 2014 return nullptr; 2015 // Can omit 'and', and just return the inverted overflow bit. 2016 return NotOp1; 2017 } 2018 2019 /// Given a bitwise logic op, check if the operands are add/sub with a common 2020 /// source value and inverted constant (identity: C - X -> ~(X + ~C)). 2021 static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1, 2022 Instruction::BinaryOps Opcode) { 2023 assert(Op0->getType() == Op1->getType() && "Mismatched binop types"); 2024 assert(BinaryOperator::isBitwiseLogicOp(Opcode) && "Expected logic op"); 2025 Value *X; 2026 Constant *C1, *C2; 2027 if ((match(Op0, m_Add(m_Value(X), m_Constant(C1))) && 2028 match(Op1, m_Sub(m_Constant(C2), m_Specific(X)))) || 2029 (match(Op1, m_Add(m_Value(X), m_Constant(C1))) && 2030 match(Op0, m_Sub(m_Constant(C2), m_Specific(X))))) { 2031 if (ConstantExpr::getNot(C1) == C2) { 2032 // (X + C) & (~C - X) --> (X + C) & ~(X + C) --> 0 2033 // (X + C) | (~C - X) --> (X + C) | ~(X + C) --> -1 2034 // (X + C) ^ (~C - X) --> (X + C) ^ ~(X + C) --> -1 2035 Type *Ty = Op0->getType(); 2036 return Opcode == Instruction::And ? ConstantInt::getNullValue(Ty) 2037 : ConstantInt::getAllOnesValue(Ty); 2038 } 2039 } 2040 return nullptr; 2041 } 2042 2043 /// Given operands for an And, see if we can fold the result. 2044 /// If not, this returns null. 2045 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2046 unsigned MaxRecurse) { 2047 if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q)) 2048 return C; 2049 2050 // X & undef -> 0 2051 if (Q.isUndefValue(Op1)) 2052 return Constant::getNullValue(Op0->getType()); 2053 2054 // X & X = X 2055 if (Op0 == Op1) 2056 return Op0; 2057 2058 // X & 0 = 0 2059 if (match(Op1, m_Zero())) 2060 return Constant::getNullValue(Op0->getType()); 2061 2062 // X & -1 = X 2063 if (match(Op1, m_AllOnes())) 2064 return Op0; 2065 2066 // A & ~A = ~A & A = 0 2067 if (match(Op0, m_Not(m_Specific(Op1))) || 2068 match(Op1, m_Not(m_Specific(Op0)))) 2069 return Constant::getNullValue(Op0->getType()); 2070 2071 // (A | ?) & A = A 2072 if (match(Op0, m_c_Or(m_Specific(Op1), m_Value()))) 2073 return Op1; 2074 2075 // A & (A | ?) = A 2076 if (match(Op1, m_c_Or(m_Specific(Op0), m_Value()))) 2077 return Op0; 2078 2079 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And)) 2080 return V; 2081 2082 // A mask that only clears known zeros of a shifted value is a no-op. 2083 Value *X; 2084 const APInt *Mask; 2085 const APInt *ShAmt; 2086 if (match(Op1, m_APInt(Mask))) { 2087 // If all bits in the inverted and shifted mask are clear: 2088 // and (shl X, ShAmt), Mask --> shl X, ShAmt 2089 if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) && 2090 (~(*Mask)).lshr(*ShAmt).isNullValue()) 2091 return Op0; 2092 2093 // If all bits in the inverted and shifted mask are clear: 2094 // and (lshr X, ShAmt), Mask --> lshr X, ShAmt 2095 if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) && 2096 (~(*Mask)).shl(*ShAmt).isNullValue()) 2097 return Op0; 2098 } 2099 2100 // If we have a multiplication overflow check that is being 'and'ed with a 2101 // check that one of the multipliers is not zero, we can omit the 'and', and 2102 // only keep the overflow check. 2103 if (Value *V = omitCheckForZeroBeforeMulWithOverflow(Op0, Op1)) 2104 return V; 2105 if (Value *V = omitCheckForZeroBeforeMulWithOverflow(Op1, Op0)) 2106 return V; 2107 2108 // A & (-A) = A if A is a power of two or zero. 2109 if (match(Op0, m_Neg(m_Specific(Op1))) || 2110 match(Op1, m_Neg(m_Specific(Op0)))) { 2111 if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, 2112 Q.DT)) 2113 return Op0; 2114 if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, 2115 Q.DT)) 2116 return Op1; 2117 } 2118 2119 // This is a similar pattern used for checking if a value is a power-of-2: 2120 // (A - 1) & A --> 0 (if A is a power-of-2 or 0) 2121 // A & (A - 1) --> 0 (if A is a power-of-2 or 0) 2122 if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) && 2123 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2124 return Constant::getNullValue(Op1->getType()); 2125 if (match(Op1, m_Add(m_Specific(Op0), m_AllOnes())) && 2126 isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2127 return Constant::getNullValue(Op0->getType()); 2128 2129 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true)) 2130 return V; 2131 2132 // Try some generic simplifications for associative operations. 2133 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, 2134 MaxRecurse)) 2135 return V; 2136 2137 // And distributes over Or. Try some generic simplifications based on this. 2138 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2139 Instruction::Or, Q, MaxRecurse)) 2140 return V; 2141 2142 // And distributes over Xor. Try some generic simplifications based on this. 2143 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2144 Instruction::Xor, Q, MaxRecurse)) 2145 return V; 2146 2147 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2148 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2149 // A & (A && B) -> A && B 2150 if (match(Op1, m_Select(m_Specific(Op0), m_Value(), m_Zero()))) 2151 return Op1; 2152 else if (match(Op0, m_Select(m_Specific(Op1), m_Value(), m_Zero()))) 2153 return Op0; 2154 } 2155 // If the operation is with the result of a select instruction, check 2156 // whether operating on either branch of the select always yields the same 2157 // value. 2158 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q, 2159 MaxRecurse)) 2160 return V; 2161 } 2162 2163 // If the operation is with the result of a phi instruction, check whether 2164 // operating on all incoming values of the phi always yields the same value. 2165 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2166 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q, 2167 MaxRecurse)) 2168 return V; 2169 2170 // Assuming the effective width of Y is not larger than A, i.e. all bits 2171 // from X and Y are disjoint in (X << A) | Y, 2172 // if the mask of this AND op covers all bits of X or Y, while it covers 2173 // no bits from the other, we can bypass this AND op. E.g., 2174 // ((X << A) | Y) & Mask -> Y, 2175 // if Mask = ((1 << effective_width_of(Y)) - 1) 2176 // ((X << A) | Y) & Mask -> X << A, 2177 // if Mask = ((1 << effective_width_of(X)) - 1) << A 2178 // SimplifyDemandedBits in InstCombine can optimize the general case. 2179 // This pattern aims to help other passes for a common case. 2180 Value *Y, *XShifted; 2181 if (match(Op1, m_APInt(Mask)) && 2182 match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)), 2183 m_Value(XShifted)), 2184 m_Value(Y)))) { 2185 const unsigned Width = Op0->getType()->getScalarSizeInBits(); 2186 const unsigned ShftCnt = ShAmt->getLimitedValue(Width); 2187 const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2188 const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros(); 2189 if (EffWidthY <= ShftCnt) { 2190 const KnownBits XKnown = computeKnownBits(X, Q.DL, 0, Q.AC, Q.CxtI, 2191 Q.DT); 2192 const unsigned EffWidthX = Width - XKnown.countMinLeadingZeros(); 2193 const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY); 2194 const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt; 2195 // If the mask is extracting all bits from X or Y as is, we can skip 2196 // this AND op. 2197 if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask)) 2198 return Y; 2199 if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask)) 2200 return XShifted; 2201 } 2202 } 2203 2204 return nullptr; 2205 } 2206 2207 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2208 return ::SimplifyAndInst(Op0, Op1, Q, RecursionLimit); 2209 } 2210 2211 /// Given operands for an Or, see if we can fold the result. 2212 /// If not, this returns null. 2213 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2214 unsigned MaxRecurse) { 2215 if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q)) 2216 return C; 2217 2218 // X | undef -> -1 2219 // X | -1 = -1 2220 // Do not return Op1 because it may contain undef elements if it's a vector. 2221 if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes())) 2222 return Constant::getAllOnesValue(Op0->getType()); 2223 2224 // X | X = X 2225 // X | 0 = X 2226 if (Op0 == Op1 || match(Op1, m_Zero())) 2227 return Op0; 2228 2229 // A | ~A = ~A | A = -1 2230 if (match(Op0, m_Not(m_Specific(Op1))) || 2231 match(Op1, m_Not(m_Specific(Op0)))) 2232 return Constant::getAllOnesValue(Op0->getType()); 2233 2234 // (A & ?) | A = A 2235 if (match(Op0, m_c_And(m_Specific(Op1), m_Value()))) 2236 return Op1; 2237 2238 // A | (A & ?) = A 2239 if (match(Op1, m_c_And(m_Specific(Op0), m_Value()))) 2240 return Op0; 2241 2242 // ~(A & ?) | A = -1 2243 if (match(Op0, m_Not(m_c_And(m_Specific(Op1), m_Value())))) 2244 return Constant::getAllOnesValue(Op1->getType()); 2245 2246 // A | ~(A & ?) = -1 2247 if (match(Op1, m_Not(m_c_And(m_Specific(Op0), m_Value())))) 2248 return Constant::getAllOnesValue(Op0->getType()); 2249 2250 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Or)) 2251 return V; 2252 2253 Value *A, *B, *NotA; 2254 // (A & ~B) | (A ^ B) -> (A ^ B) 2255 // (~B & A) | (A ^ B) -> (A ^ B) 2256 // (A & ~B) | (B ^ A) -> (B ^ A) 2257 // (~B & A) | (B ^ A) -> (B ^ A) 2258 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && 2259 (match(Op0, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) || 2260 match(Op0, m_c_And(m_Not(m_Specific(A)), m_Specific(B))))) 2261 return Op1; 2262 2263 // Commute the 'or' operands. 2264 // (A ^ B) | (A & ~B) -> (A ^ B) 2265 // (A ^ B) | (~B & A) -> (A ^ B) 2266 // (B ^ A) | (A & ~B) -> (B ^ A) 2267 // (B ^ A) | (~B & A) -> (B ^ A) 2268 if (match(Op0, m_Xor(m_Value(A), m_Value(B))) && 2269 (match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) || 2270 match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B))))) 2271 return Op0; 2272 2273 // (A & B) | (~A ^ B) -> (~A ^ B) 2274 // (B & A) | (~A ^ B) -> (~A ^ B) 2275 // (A & B) | (B ^ ~A) -> (B ^ ~A) 2276 // (B & A) | (B ^ ~A) -> (B ^ ~A) 2277 if (match(Op0, m_And(m_Value(A), m_Value(B))) && 2278 (match(Op1, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) || 2279 match(Op1, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B))))) 2280 return Op1; 2281 2282 // Commute the 'or' operands. 2283 // (~A ^ B) | (A & B) -> (~A ^ B) 2284 // (~A ^ B) | (B & A) -> (~A ^ B) 2285 // (B ^ ~A) | (A & B) -> (B ^ ~A) 2286 // (B ^ ~A) | (B & A) -> (B ^ ~A) 2287 if (match(Op1, m_And(m_Value(A), m_Value(B))) && 2288 (match(Op0, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) || 2289 match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B))))) 2290 return Op0; 2291 2292 // (~A & B) | ~(A | B) --> ~A 2293 // (~A & B) | ~(B | A) --> ~A 2294 // (B & ~A) | ~(A | B) --> ~A 2295 // (B & ~A) | ~(B | A) --> ~A 2296 if (match(Op0, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))), 2297 m_Value(B))) && 2298 match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) 2299 return NotA; 2300 2301 // Commute the 'or' operands. 2302 // ~(A | B) | (~A & B) --> ~A 2303 // ~(B | A) | (~A & B) --> ~A 2304 // ~(A | B) | (B & ~A) --> ~A 2305 // ~(B | A) | (B & ~A) --> ~A 2306 if (match(Op1, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))), 2307 m_Value(B))) && 2308 match(Op0, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) 2309 return NotA; 2310 2311 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false)) 2312 return V; 2313 2314 // If we have a multiplication overflow check that is being 'and'ed with a 2315 // check that one of the multipliers is not zero, we can omit the 'and', and 2316 // only keep the overflow check. 2317 if (Value *V = omitCheckForZeroBeforeInvertedMulWithOverflow(Op0, Op1)) 2318 return V; 2319 if (Value *V = omitCheckForZeroBeforeInvertedMulWithOverflow(Op1, Op0)) 2320 return V; 2321 2322 // Try some generic simplifications for associative operations. 2323 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, 2324 MaxRecurse)) 2325 return V; 2326 2327 // Or distributes over And. Try some generic simplifications based on this. 2328 if (Value *V = expandCommutativeBinOp(Instruction::Or, Op0, Op1, 2329 Instruction::And, Q, MaxRecurse)) 2330 return V; 2331 2332 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2333 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2334 // A | (A || B) -> A || B 2335 if (match(Op1, m_Select(m_Specific(Op0), m_One(), m_Value()))) 2336 return Op1; 2337 else if (match(Op0, m_Select(m_Specific(Op1), m_One(), m_Value()))) 2338 return Op0; 2339 } 2340 // If the operation is with the result of a select instruction, check 2341 // whether operating on either branch of the select always yields the same 2342 // value. 2343 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, 2344 MaxRecurse)) 2345 return V; 2346 } 2347 2348 // (A & C1)|(B & C2) 2349 const APInt *C1, *C2; 2350 if (match(Op0, m_And(m_Value(A), m_APInt(C1))) && 2351 match(Op1, m_And(m_Value(B), m_APInt(C2)))) { 2352 if (*C1 == ~*C2) { 2353 // (A & C1)|(B & C2) 2354 // If we have: ((V + N) & C1) | (V & C2) 2355 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 2356 // replace with V+N. 2357 Value *N; 2358 if (C2->isMask() && // C2 == 0+1+ 2359 match(A, m_c_Add(m_Specific(B), m_Value(N)))) { 2360 // Add commutes, try both ways. 2361 if (MaskedValueIsZero(N, *C2, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2362 return A; 2363 } 2364 // Or commutes, try both ways. 2365 if (C1->isMask() && 2366 match(B, m_c_Add(m_Specific(A), m_Value(N)))) { 2367 // Add commutes, try both ways. 2368 if (MaskedValueIsZero(N, *C1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2369 return B; 2370 } 2371 } 2372 } 2373 2374 // If the operation is with the result of a phi instruction, check whether 2375 // operating on all incoming values of the phi always yields the same value. 2376 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2377 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2378 return V; 2379 2380 return nullptr; 2381 } 2382 2383 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2384 return ::SimplifyOrInst(Op0, Op1, Q, RecursionLimit); 2385 } 2386 2387 /// Given operands for a Xor, see if we can fold the result. 2388 /// If not, this returns null. 2389 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2390 unsigned MaxRecurse) { 2391 if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q)) 2392 return C; 2393 2394 // A ^ undef -> undef 2395 if (Q.isUndefValue(Op1)) 2396 return Op1; 2397 2398 // A ^ 0 = A 2399 if (match(Op1, m_Zero())) 2400 return Op0; 2401 2402 // A ^ A = 0 2403 if (Op0 == Op1) 2404 return Constant::getNullValue(Op0->getType()); 2405 2406 // A ^ ~A = ~A ^ A = -1 2407 if (match(Op0, m_Not(m_Specific(Op1))) || 2408 match(Op1, m_Not(m_Specific(Op0)))) 2409 return Constant::getAllOnesValue(Op0->getType()); 2410 2411 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor)) 2412 return V; 2413 2414 // Try some generic simplifications for associative operations. 2415 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, 2416 MaxRecurse)) 2417 return V; 2418 2419 // Threading Xor over selects and phi nodes is pointless, so don't bother. 2420 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 2421 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 2422 // only if B and C are equal. If B and C are equal then (since we assume 2423 // that operands have already been simplified) "select(cond, B, C)" should 2424 // have been simplified to the common value of B and C already. Analysing 2425 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 2426 // for threading over phi nodes. 2427 2428 return nullptr; 2429 } 2430 2431 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2432 return ::SimplifyXorInst(Op0, Op1, Q, RecursionLimit); 2433 } 2434 2435 2436 static Type *GetCompareTy(Value *Op) { 2437 return CmpInst::makeCmpResultType(Op->getType()); 2438 } 2439 2440 /// Rummage around inside V looking for something equivalent to the comparison 2441 /// "LHS Pred RHS". Return such a value if found, otherwise return null. 2442 /// Helper function for analyzing max/min idioms. 2443 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 2444 Value *LHS, Value *RHS) { 2445 SelectInst *SI = dyn_cast<SelectInst>(V); 2446 if (!SI) 2447 return nullptr; 2448 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 2449 if (!Cmp) 2450 return nullptr; 2451 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 2452 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 2453 return Cmp; 2454 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 2455 LHS == CmpRHS && RHS == CmpLHS) 2456 return Cmp; 2457 return nullptr; 2458 } 2459 2460 // A significant optimization not implemented here is assuming that alloca 2461 // addresses are not equal to incoming argument values. They don't *alias*, 2462 // as we say, but that doesn't mean they aren't equal, so we take a 2463 // conservative approach. 2464 // 2465 // This is inspired in part by C++11 5.10p1: 2466 // "Two pointers of the same type compare equal if and only if they are both 2467 // null, both point to the same function, or both represent the same 2468 // address." 2469 // 2470 // This is pretty permissive. 2471 // 2472 // It's also partly due to C11 6.5.9p6: 2473 // "Two pointers compare equal if and only if both are null pointers, both are 2474 // pointers to the same object (including a pointer to an object and a 2475 // subobject at its beginning) or function, both are pointers to one past the 2476 // last element of the same array object, or one is a pointer to one past the 2477 // end of one array object and the other is a pointer to the start of a 2478 // different array object that happens to immediately follow the first array 2479 // object in the address space.) 2480 // 2481 // C11's version is more restrictive, however there's no reason why an argument 2482 // couldn't be a one-past-the-end value for a stack object in the caller and be 2483 // equal to the beginning of a stack object in the callee. 2484 // 2485 // If the C and C++ standards are ever made sufficiently restrictive in this 2486 // area, it may be possible to update LLVM's semantics accordingly and reinstate 2487 // this optimization. 2488 static Constant * 2489 computePointerICmp(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 2490 const SimplifyQuery &Q) { 2491 const DataLayout &DL = Q.DL; 2492 const TargetLibraryInfo *TLI = Q.TLI; 2493 const DominatorTree *DT = Q.DT; 2494 const Instruction *CxtI = Q.CxtI; 2495 const InstrInfoQuery &IIQ = Q.IIQ; 2496 2497 // First, skip past any trivial no-ops. 2498 LHS = LHS->stripPointerCasts(); 2499 RHS = RHS->stripPointerCasts(); 2500 2501 // A non-null pointer is not equal to a null pointer. 2502 if (isa<ConstantPointerNull>(RHS) && ICmpInst::isEquality(Pred) && 2503 llvm::isKnownNonZero(LHS, DL, 0, nullptr, nullptr, nullptr, 2504 IIQ.UseInstrInfo)) 2505 return ConstantInt::get(GetCompareTy(LHS), 2506 !CmpInst::isTrueWhenEqual(Pred)); 2507 2508 // We can only fold certain predicates on pointer comparisons. 2509 switch (Pred) { 2510 default: 2511 return nullptr; 2512 2513 // Equality comaprisons are easy to fold. 2514 case CmpInst::ICMP_EQ: 2515 case CmpInst::ICMP_NE: 2516 break; 2517 2518 // We can only handle unsigned relational comparisons because 'inbounds' on 2519 // a GEP only protects against unsigned wrapping. 2520 case CmpInst::ICMP_UGT: 2521 case CmpInst::ICMP_UGE: 2522 case CmpInst::ICMP_ULT: 2523 case CmpInst::ICMP_ULE: 2524 // However, we have to switch them to their signed variants to handle 2525 // negative indices from the base pointer. 2526 Pred = ICmpInst::getSignedPredicate(Pred); 2527 break; 2528 } 2529 2530 // Strip off any constant offsets so that we can reason about them. 2531 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets 2532 // here and compare base addresses like AliasAnalysis does, however there are 2533 // numerous hazards. AliasAnalysis and its utilities rely on special rules 2534 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis 2535 // doesn't need to guarantee pointer inequality when it says NoAlias. 2536 Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS); 2537 Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS); 2538 2539 // If LHS and RHS are related via constant offsets to the same base 2540 // value, we can replace it with an icmp which just compares the offsets. 2541 if (LHS == RHS) 2542 return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset); 2543 2544 // Various optimizations for (in)equality comparisons. 2545 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) { 2546 // Different non-empty allocations that exist at the same time have 2547 // different addresses (if the program can tell). Global variables always 2548 // exist, so they always exist during the lifetime of each other and all 2549 // allocas. Two different allocas usually have different addresses... 2550 // 2551 // However, if there's an @llvm.stackrestore dynamically in between two 2552 // allocas, they may have the same address. It's tempting to reduce the 2553 // scope of the problem by only looking at *static* allocas here. That would 2554 // cover the majority of allocas while significantly reducing the likelihood 2555 // of having an @llvm.stackrestore pop up in the middle. However, it's not 2556 // actually impossible for an @llvm.stackrestore to pop up in the middle of 2557 // an entry block. Also, if we have a block that's not attached to a 2558 // function, we can't tell if it's "static" under the current definition. 2559 // Theoretically, this problem could be fixed by creating a new kind of 2560 // instruction kind specifically for static allocas. Such a new instruction 2561 // could be required to be at the top of the entry block, thus preventing it 2562 // from being subject to a @llvm.stackrestore. Instcombine could even 2563 // convert regular allocas into these special allocas. It'd be nifty. 2564 // However, until then, this problem remains open. 2565 // 2566 // So, we'll assume that two non-empty allocas have different addresses 2567 // for now. 2568 // 2569 // With all that, if the offsets are within the bounds of their allocations 2570 // (and not one-past-the-end! so we can't use inbounds!), and their 2571 // allocations aren't the same, the pointers are not equal. 2572 // 2573 // Note that it's not necessary to check for LHS being a global variable 2574 // address, due to canonicalization and constant folding. 2575 if (isa<AllocaInst>(LHS) && 2576 (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) { 2577 ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset); 2578 ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset); 2579 uint64_t LHSSize, RHSSize; 2580 ObjectSizeOpts Opts; 2581 Opts.NullIsUnknownSize = 2582 NullPointerIsDefined(cast<AllocaInst>(LHS)->getFunction()); 2583 if (LHSOffsetCI && RHSOffsetCI && 2584 getObjectSize(LHS, LHSSize, DL, TLI, Opts) && 2585 getObjectSize(RHS, RHSSize, DL, TLI, Opts)) { 2586 const APInt &LHSOffsetValue = LHSOffsetCI->getValue(); 2587 const APInt &RHSOffsetValue = RHSOffsetCI->getValue(); 2588 if (!LHSOffsetValue.isNegative() && 2589 !RHSOffsetValue.isNegative() && 2590 LHSOffsetValue.ult(LHSSize) && 2591 RHSOffsetValue.ult(RHSSize)) { 2592 return ConstantInt::get(GetCompareTy(LHS), 2593 !CmpInst::isTrueWhenEqual(Pred)); 2594 } 2595 } 2596 2597 // Repeat the above check but this time without depending on DataLayout 2598 // or being able to compute a precise size. 2599 if (!cast<PointerType>(LHS->getType())->isEmptyTy() && 2600 !cast<PointerType>(RHS->getType())->isEmptyTy() && 2601 LHSOffset->isNullValue() && 2602 RHSOffset->isNullValue()) 2603 return ConstantInt::get(GetCompareTy(LHS), 2604 !CmpInst::isTrueWhenEqual(Pred)); 2605 } 2606 2607 // Even if an non-inbounds GEP occurs along the path we can still optimize 2608 // equality comparisons concerning the result. We avoid walking the whole 2609 // chain again by starting where the last calls to 2610 // stripAndComputeConstantOffsets left off and accumulate the offsets. 2611 Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true); 2612 Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true); 2613 if (LHS == RHS) 2614 return ConstantExpr::getICmp(Pred, 2615 ConstantExpr::getAdd(LHSOffset, LHSNoBound), 2616 ConstantExpr::getAdd(RHSOffset, RHSNoBound)); 2617 2618 // If one side of the equality comparison must come from a noalias call 2619 // (meaning a system memory allocation function), and the other side must 2620 // come from a pointer that cannot overlap with dynamically-allocated 2621 // memory within the lifetime of the current function (allocas, byval 2622 // arguments, globals), then determine the comparison result here. 2623 SmallVector<const Value *, 8> LHSUObjs, RHSUObjs; 2624 getUnderlyingObjects(LHS, LHSUObjs); 2625 getUnderlyingObjects(RHS, RHSUObjs); 2626 2627 // Is the set of underlying objects all noalias calls? 2628 auto IsNAC = [](ArrayRef<const Value *> Objects) { 2629 return all_of(Objects, isNoAliasCall); 2630 }; 2631 2632 // Is the set of underlying objects all things which must be disjoint from 2633 // noalias calls. For allocas, we consider only static ones (dynamic 2634 // allocas might be transformed into calls to malloc not simultaneously 2635 // live with the compared-to allocation). For globals, we exclude symbols 2636 // that might be resolve lazily to symbols in another dynamically-loaded 2637 // library (and, thus, could be malloc'ed by the implementation). 2638 auto IsAllocDisjoint = [](ArrayRef<const Value *> Objects) { 2639 return all_of(Objects, [](const Value *V) { 2640 if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) 2641 return AI->getParent() && AI->getFunction() && AI->isStaticAlloca(); 2642 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) 2643 return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() || 2644 GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) && 2645 !GV->isThreadLocal(); 2646 if (const Argument *A = dyn_cast<Argument>(V)) 2647 return A->hasByValAttr(); 2648 return false; 2649 }); 2650 }; 2651 2652 if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) || 2653 (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs))) 2654 return ConstantInt::get(GetCompareTy(LHS), 2655 !CmpInst::isTrueWhenEqual(Pred)); 2656 2657 // Fold comparisons for non-escaping pointer even if the allocation call 2658 // cannot be elided. We cannot fold malloc comparison to null. Also, the 2659 // dynamic allocation call could be either of the operands. 2660 Value *MI = nullptr; 2661 if (isAllocLikeFn(LHS, TLI) && 2662 llvm::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT)) 2663 MI = LHS; 2664 else if (isAllocLikeFn(RHS, TLI) && 2665 llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT)) 2666 MI = RHS; 2667 // FIXME: We should also fold the compare when the pointer escapes, but the 2668 // compare dominates the pointer escape 2669 if (MI && !PointerMayBeCaptured(MI, true, true)) 2670 return ConstantInt::get(GetCompareTy(LHS), 2671 CmpInst::isFalseWhenEqual(Pred)); 2672 } 2673 2674 // Otherwise, fail. 2675 return nullptr; 2676 } 2677 2678 /// Fold an icmp when its operands have i1 scalar type. 2679 static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS, 2680 Value *RHS, const SimplifyQuery &Q) { 2681 Type *ITy = GetCompareTy(LHS); // The return type. 2682 Type *OpTy = LHS->getType(); // The operand type. 2683 if (!OpTy->isIntOrIntVectorTy(1)) 2684 return nullptr; 2685 2686 // A boolean compared to true/false can be simplified in 14 out of the 20 2687 // (10 predicates * 2 constants) possible combinations. Cases not handled here 2688 // require a 'not' of the LHS, so those must be transformed in InstCombine. 2689 if (match(RHS, m_Zero())) { 2690 switch (Pred) { 2691 case CmpInst::ICMP_NE: // X != 0 -> X 2692 case CmpInst::ICMP_UGT: // X >u 0 -> X 2693 case CmpInst::ICMP_SLT: // X <s 0 -> X 2694 return LHS; 2695 2696 case CmpInst::ICMP_ULT: // X <u 0 -> false 2697 case CmpInst::ICMP_SGT: // X >s 0 -> false 2698 return getFalse(ITy); 2699 2700 case CmpInst::ICMP_UGE: // X >=u 0 -> true 2701 case CmpInst::ICMP_SLE: // X <=s 0 -> true 2702 return getTrue(ITy); 2703 2704 default: break; 2705 } 2706 } else if (match(RHS, m_One())) { 2707 switch (Pred) { 2708 case CmpInst::ICMP_EQ: // X == 1 -> X 2709 case CmpInst::ICMP_UGE: // X >=u 1 -> X 2710 case CmpInst::ICMP_SLE: // X <=s -1 -> X 2711 return LHS; 2712 2713 case CmpInst::ICMP_UGT: // X >u 1 -> false 2714 case CmpInst::ICMP_SLT: // X <s -1 -> false 2715 return getFalse(ITy); 2716 2717 case CmpInst::ICMP_ULE: // X <=u 1 -> true 2718 case CmpInst::ICMP_SGE: // X >=s -1 -> true 2719 return getTrue(ITy); 2720 2721 default: break; 2722 } 2723 } 2724 2725 switch (Pred) { 2726 default: 2727 break; 2728 case ICmpInst::ICMP_UGE: 2729 if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false)) 2730 return getTrue(ITy); 2731 break; 2732 case ICmpInst::ICMP_SGE: 2733 /// For signed comparison, the values for an i1 are 0 and -1 2734 /// respectively. This maps into a truth table of: 2735 /// LHS | RHS | LHS >=s RHS | LHS implies RHS 2736 /// 0 | 0 | 1 (0 >= 0) | 1 2737 /// 0 | 1 | 1 (0 >= -1) | 1 2738 /// 1 | 0 | 0 (-1 >= 0) | 0 2739 /// 1 | 1 | 1 (-1 >= -1) | 1 2740 if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false)) 2741 return getTrue(ITy); 2742 break; 2743 case ICmpInst::ICMP_ULE: 2744 if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false)) 2745 return getTrue(ITy); 2746 break; 2747 } 2748 2749 return nullptr; 2750 } 2751 2752 /// Try hard to fold icmp with zero RHS because this is a common case. 2753 static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS, 2754 Value *RHS, const SimplifyQuery &Q) { 2755 if (!match(RHS, m_Zero())) 2756 return nullptr; 2757 2758 Type *ITy = GetCompareTy(LHS); // The return type. 2759 switch (Pred) { 2760 default: 2761 llvm_unreachable("Unknown ICmp predicate!"); 2762 case ICmpInst::ICMP_ULT: 2763 return getFalse(ITy); 2764 case ICmpInst::ICMP_UGE: 2765 return getTrue(ITy); 2766 case ICmpInst::ICMP_EQ: 2767 case ICmpInst::ICMP_ULE: 2768 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2769 return getFalse(ITy); 2770 break; 2771 case ICmpInst::ICMP_NE: 2772 case ICmpInst::ICMP_UGT: 2773 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2774 return getTrue(ITy); 2775 break; 2776 case ICmpInst::ICMP_SLT: { 2777 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2778 if (LHSKnown.isNegative()) 2779 return getTrue(ITy); 2780 if (LHSKnown.isNonNegative()) 2781 return getFalse(ITy); 2782 break; 2783 } 2784 case ICmpInst::ICMP_SLE: { 2785 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2786 if (LHSKnown.isNegative()) 2787 return getTrue(ITy); 2788 if (LHSKnown.isNonNegative() && 2789 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2790 return getFalse(ITy); 2791 break; 2792 } 2793 case ICmpInst::ICMP_SGE: { 2794 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2795 if (LHSKnown.isNegative()) 2796 return getFalse(ITy); 2797 if (LHSKnown.isNonNegative()) 2798 return getTrue(ITy); 2799 break; 2800 } 2801 case ICmpInst::ICMP_SGT: { 2802 KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2803 if (LHSKnown.isNegative()) 2804 return getFalse(ITy); 2805 if (LHSKnown.isNonNegative() && 2806 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 2807 return getTrue(ITy); 2808 break; 2809 } 2810 } 2811 2812 return nullptr; 2813 } 2814 2815 static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS, 2816 Value *RHS, const InstrInfoQuery &IIQ) { 2817 Type *ITy = GetCompareTy(RHS); // The return type. 2818 2819 Value *X; 2820 // Sign-bit checks can be optimized to true/false after unsigned 2821 // floating-point casts: 2822 // icmp slt (bitcast (uitofp X)), 0 --> false 2823 // icmp sgt (bitcast (uitofp X)), -1 --> true 2824 if (match(LHS, m_BitCast(m_UIToFP(m_Value(X))))) { 2825 if (Pred == ICmpInst::ICMP_SLT && match(RHS, m_Zero())) 2826 return ConstantInt::getFalse(ITy); 2827 if (Pred == ICmpInst::ICMP_SGT && match(RHS, m_AllOnes())) 2828 return ConstantInt::getTrue(ITy); 2829 } 2830 2831 const APInt *C; 2832 if (!match(RHS, m_APIntAllowUndef(C))) 2833 return nullptr; 2834 2835 // Rule out tautological comparisons (eg., ult 0 or uge 0). 2836 ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C); 2837 if (RHS_CR.isEmptySet()) 2838 return ConstantInt::getFalse(ITy); 2839 if (RHS_CR.isFullSet()) 2840 return ConstantInt::getTrue(ITy); 2841 2842 ConstantRange LHS_CR = computeConstantRange(LHS, IIQ.UseInstrInfo); 2843 if (!LHS_CR.isFullSet()) { 2844 if (RHS_CR.contains(LHS_CR)) 2845 return ConstantInt::getTrue(ITy); 2846 if (RHS_CR.inverse().contains(LHS_CR)) 2847 return ConstantInt::getFalse(ITy); 2848 } 2849 2850 // (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC) 2851 // (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC) 2852 const APInt *MulC; 2853 if (ICmpInst::isEquality(Pred) && 2854 ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowUndef(MulC))) && 2855 *MulC != 0 && C->urem(*MulC) != 0) || 2856 (match(LHS, m_NSWMul(m_Value(), m_APIntAllowUndef(MulC))) && 2857 *MulC != 0 && C->srem(*MulC) != 0))) 2858 return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE); 2859 2860 return nullptr; 2861 } 2862 2863 static Value *simplifyICmpWithBinOpOnLHS( 2864 CmpInst::Predicate Pred, BinaryOperator *LBO, Value *RHS, 2865 const SimplifyQuery &Q, unsigned MaxRecurse) { 2866 Type *ITy = GetCompareTy(RHS); // The return type. 2867 2868 Value *Y = nullptr; 2869 // icmp pred (or X, Y), X 2870 if (match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) { 2871 if (Pred == ICmpInst::ICMP_ULT) 2872 return getFalse(ITy); 2873 if (Pred == ICmpInst::ICMP_UGE) 2874 return getTrue(ITy); 2875 2876 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) { 2877 KnownBits RHSKnown = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2878 KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2879 if (RHSKnown.isNonNegative() && YKnown.isNegative()) 2880 return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy); 2881 if (RHSKnown.isNegative() || YKnown.isNonNegative()) 2882 return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy); 2883 } 2884 } 2885 2886 // icmp pred (and X, Y), X 2887 if (match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) { 2888 if (Pred == ICmpInst::ICMP_UGT) 2889 return getFalse(ITy); 2890 if (Pred == ICmpInst::ICMP_ULE) 2891 return getTrue(ITy); 2892 } 2893 2894 // icmp pred (urem X, Y), Y 2895 if (match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 2896 switch (Pred) { 2897 default: 2898 break; 2899 case ICmpInst::ICMP_SGT: 2900 case ICmpInst::ICMP_SGE: { 2901 KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2902 if (!Known.isNonNegative()) 2903 break; 2904 LLVM_FALLTHROUGH; 2905 } 2906 case ICmpInst::ICMP_EQ: 2907 case ICmpInst::ICMP_UGT: 2908 case ICmpInst::ICMP_UGE: 2909 return getFalse(ITy); 2910 case ICmpInst::ICMP_SLT: 2911 case ICmpInst::ICMP_SLE: { 2912 KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 2913 if (!Known.isNonNegative()) 2914 break; 2915 LLVM_FALLTHROUGH; 2916 } 2917 case ICmpInst::ICMP_NE: 2918 case ICmpInst::ICMP_ULT: 2919 case ICmpInst::ICMP_ULE: 2920 return getTrue(ITy); 2921 } 2922 } 2923 2924 // icmp pred (urem X, Y), X 2925 if (match(LBO, m_URem(m_Specific(RHS), m_Value()))) { 2926 if (Pred == ICmpInst::ICMP_ULE) 2927 return getTrue(ITy); 2928 if (Pred == ICmpInst::ICMP_UGT) 2929 return getFalse(ITy); 2930 } 2931 2932 // x >> y <=u x 2933 // x udiv y <=u x. 2934 if (match(LBO, m_LShr(m_Specific(RHS), m_Value())) || 2935 match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) { 2936 // icmp pred (X op Y), X 2937 if (Pred == ICmpInst::ICMP_UGT) 2938 return getFalse(ITy); 2939 if (Pred == ICmpInst::ICMP_ULE) 2940 return getTrue(ITy); 2941 } 2942 2943 // (x*C1)/C2 <= x for C1 <= C2. 2944 // This holds even if the multiplication overflows: Assume that x != 0 and 2945 // arithmetic is modulo M. For overflow to occur we must have C1 >= M/x and 2946 // thus C2 >= M/x. It follows that (x*C1)/C2 <= (M-1)/C2 <= ((M-1)*x)/M < x. 2947 // 2948 // Additionally, either the multiplication and division might be represented 2949 // as shifts: 2950 // (x*C1)>>C2 <= x for C1 < 2**C2. 2951 // (x<<C1)/C2 <= x for 2**C1 < C2. 2952 const APInt *C1, *C2; 2953 if ((match(LBO, m_UDiv(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 2954 C1->ule(*C2)) || 2955 (match(LBO, m_LShr(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 2956 C1->ule(APInt(C2->getBitWidth(), 1) << *C2)) || 2957 (match(LBO, m_UDiv(m_Shl(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 2958 (APInt(C1->getBitWidth(), 1) << *C1).ule(*C2))) { 2959 if (Pred == ICmpInst::ICMP_UGT) 2960 return getFalse(ITy); 2961 if (Pred == ICmpInst::ICMP_ULE) 2962 return getTrue(ITy); 2963 } 2964 2965 return nullptr; 2966 } 2967 2968 2969 // If only one of the icmp's operands has NSW flags, try to prove that: 2970 // 2971 // icmp slt (x + C1), (x +nsw C2) 2972 // 2973 // is equivalent to: 2974 // 2975 // icmp slt C1, C2 2976 // 2977 // which is true if x + C2 has the NSW flags set and: 2978 // *) C1 < C2 && C1 >= 0, or 2979 // *) C2 < C1 && C1 <= 0. 2980 // 2981 static bool trySimplifyICmpWithAdds(CmpInst::Predicate Pred, Value *LHS, 2982 Value *RHS) { 2983 // TODO: only support icmp slt for now. 2984 if (Pred != CmpInst::ICMP_SLT) 2985 return false; 2986 2987 // Canonicalize nsw add as RHS. 2988 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 2989 std::swap(LHS, RHS); 2990 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 2991 return false; 2992 2993 Value *X; 2994 const APInt *C1, *C2; 2995 if (!match(LHS, m_c_Add(m_Value(X), m_APInt(C1))) || 2996 !match(RHS, m_c_Add(m_Specific(X), m_APInt(C2)))) 2997 return false; 2998 2999 return (C1->slt(*C2) && C1->isNonNegative()) || 3000 (C2->slt(*C1) && C1->isNonPositive()); 3001 } 3002 3003 3004 /// TODO: A large part of this logic is duplicated in InstCombine's 3005 /// foldICmpBinOp(). We should be able to share that and avoid the code 3006 /// duplication. 3007 static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS, 3008 Value *RHS, const SimplifyQuery &Q, 3009 unsigned MaxRecurse) { 3010 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 3011 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 3012 if (MaxRecurse && (LBO || RBO)) { 3013 // Analyze the case when either LHS or RHS is an add instruction. 3014 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr; 3015 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 3016 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 3017 if (LBO && LBO->getOpcode() == Instruction::Add) { 3018 A = LBO->getOperand(0); 3019 B = LBO->getOperand(1); 3020 NoLHSWrapProblem = 3021 ICmpInst::isEquality(Pred) || 3022 (CmpInst::isUnsigned(Pred) && 3023 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) || 3024 (CmpInst::isSigned(Pred) && 3025 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO))); 3026 } 3027 if (RBO && RBO->getOpcode() == Instruction::Add) { 3028 C = RBO->getOperand(0); 3029 D = RBO->getOperand(1); 3030 NoRHSWrapProblem = 3031 ICmpInst::isEquality(Pred) || 3032 (CmpInst::isUnsigned(Pred) && 3033 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) || 3034 (CmpInst::isSigned(Pred) && 3035 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO))); 3036 } 3037 3038 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 3039 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 3040 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A, 3041 Constant::getNullValue(RHS->getType()), Q, 3042 MaxRecurse - 1)) 3043 return V; 3044 3045 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 3046 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 3047 if (Value *V = 3048 SimplifyICmpInst(Pred, Constant::getNullValue(LHS->getType()), 3049 C == LHS ? D : C, Q, MaxRecurse - 1)) 3050 return V; 3051 3052 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 3053 bool CanSimplify = (NoLHSWrapProblem && NoRHSWrapProblem) || 3054 trySimplifyICmpWithAdds(Pred, LHS, RHS); 3055 if (A && C && (A == C || A == D || B == C || B == D) && CanSimplify) { 3056 // Determine Y and Z in the form icmp (X+Y), (X+Z). 3057 Value *Y, *Z; 3058 if (A == C) { 3059 // C + B == C + D -> B == D 3060 Y = B; 3061 Z = D; 3062 } else if (A == D) { 3063 // D + B == C + D -> B == C 3064 Y = B; 3065 Z = C; 3066 } else if (B == C) { 3067 // A + C == C + D -> A == D 3068 Y = A; 3069 Z = D; 3070 } else { 3071 assert(B == D); 3072 // A + D == C + D -> A == C 3073 Y = A; 3074 Z = C; 3075 } 3076 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1)) 3077 return V; 3078 } 3079 } 3080 3081 if (LBO) 3082 if (Value *V = simplifyICmpWithBinOpOnLHS(Pred, LBO, RHS, Q, MaxRecurse)) 3083 return V; 3084 3085 if (RBO) 3086 if (Value *V = simplifyICmpWithBinOpOnLHS( 3087 ICmpInst::getSwappedPredicate(Pred), RBO, LHS, Q, MaxRecurse)) 3088 return V; 3089 3090 // 0 - (zext X) pred C 3091 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) { 3092 const APInt *C; 3093 if (match(RHS, m_APInt(C))) { 3094 if (C->isStrictlyPositive()) { 3095 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_NE) 3096 return ConstantInt::getTrue(GetCompareTy(RHS)); 3097 if (Pred == ICmpInst::ICMP_SGE || Pred == ICmpInst::ICMP_EQ) 3098 return ConstantInt::getFalse(GetCompareTy(RHS)); 3099 } 3100 if (C->isNonNegative()) { 3101 if (Pred == ICmpInst::ICMP_SLE) 3102 return ConstantInt::getTrue(GetCompareTy(RHS)); 3103 if (Pred == ICmpInst::ICMP_SGT) 3104 return ConstantInt::getFalse(GetCompareTy(RHS)); 3105 } 3106 } 3107 } 3108 3109 // If C2 is a power-of-2 and C is not: 3110 // (C2 << X) == C --> false 3111 // (C2 << X) != C --> true 3112 const APInt *C; 3113 if (match(LHS, m_Shl(m_Power2(), m_Value())) && 3114 match(RHS, m_APIntAllowUndef(C)) && !C->isPowerOf2()) { 3115 // C2 << X can equal zero in some circumstances. 3116 // This simplification might be unsafe if C is zero. 3117 // 3118 // We know it is safe if: 3119 // - The shift is nsw. We can't shift out the one bit. 3120 // - The shift is nuw. We can't shift out the one bit. 3121 // - C2 is one. 3122 // - C isn't zero. 3123 if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3124 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3125 match(LHS, m_Shl(m_One(), m_Value())) || !C->isNullValue()) { 3126 if (Pred == ICmpInst::ICMP_EQ) 3127 return ConstantInt::getFalse(GetCompareTy(RHS)); 3128 if (Pred == ICmpInst::ICMP_NE) 3129 return ConstantInt::getTrue(GetCompareTy(RHS)); 3130 } 3131 } 3132 3133 // TODO: This is overly constrained. LHS can be any power-of-2. 3134 // (1 << X) >u 0x8000 --> false 3135 // (1 << X) <=u 0x8000 --> true 3136 if (match(LHS, m_Shl(m_One(), m_Value())) && match(RHS, m_SignMask())) { 3137 if (Pred == ICmpInst::ICMP_UGT) 3138 return ConstantInt::getFalse(GetCompareTy(RHS)); 3139 if (Pred == ICmpInst::ICMP_ULE) 3140 return ConstantInt::getTrue(GetCompareTy(RHS)); 3141 } 3142 3143 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() && 3144 LBO->getOperand(1) == RBO->getOperand(1)) { 3145 switch (LBO->getOpcode()) { 3146 default: 3147 break; 3148 case Instruction::UDiv: 3149 case Instruction::LShr: 3150 if (ICmpInst::isSigned(Pred) || !Q.IIQ.isExact(LBO) || 3151 !Q.IIQ.isExact(RBO)) 3152 break; 3153 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3154 RBO->getOperand(0), Q, MaxRecurse - 1)) 3155 return V; 3156 break; 3157 case Instruction::SDiv: 3158 if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) || 3159 !Q.IIQ.isExact(RBO)) 3160 break; 3161 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3162 RBO->getOperand(0), Q, MaxRecurse - 1)) 3163 return V; 3164 break; 3165 case Instruction::AShr: 3166 if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO)) 3167 break; 3168 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3169 RBO->getOperand(0), Q, MaxRecurse - 1)) 3170 return V; 3171 break; 3172 case Instruction::Shl: { 3173 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3174 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3175 if (!NUW && !NSW) 3176 break; 3177 if (!NSW && ICmpInst::isSigned(Pred)) 3178 break; 3179 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 3180 RBO->getOperand(0), Q, MaxRecurse - 1)) 3181 return V; 3182 break; 3183 } 3184 } 3185 } 3186 return nullptr; 3187 } 3188 3189 /// Simplify integer comparisons where at least one operand of the compare 3190 /// matches an integer min/max idiom. 3191 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS, 3192 Value *RHS, const SimplifyQuery &Q, 3193 unsigned MaxRecurse) { 3194 Type *ITy = GetCompareTy(LHS); // The return type. 3195 Value *A, *B; 3196 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 3197 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 3198 3199 // Signed variants on "max(a,b)>=a -> true". 3200 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3201 if (A != RHS) 3202 std::swap(A, B); // smax(A, B) pred A. 3203 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3204 // We analyze this as smax(A, B) pred A. 3205 P = Pred; 3206 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 3207 (A == LHS || B == LHS)) { 3208 if (A != LHS) 3209 std::swap(A, B); // A pred smax(A, B). 3210 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3211 // We analyze this as smax(A, B) swapped-pred A. 3212 P = CmpInst::getSwappedPredicate(Pred); 3213 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 3214 (A == RHS || B == RHS)) { 3215 if (A != RHS) 3216 std::swap(A, B); // smin(A, B) pred A. 3217 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3218 // We analyze this as smax(-A, -B) swapped-pred -A. 3219 // Note that we do not need to actually form -A or -B thanks to EqP. 3220 P = CmpInst::getSwappedPredicate(Pred); 3221 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 3222 (A == LHS || B == LHS)) { 3223 if (A != LHS) 3224 std::swap(A, B); // A pred smin(A, B). 3225 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3226 // We analyze this as smax(-A, -B) pred -A. 3227 // Note that we do not need to actually form -A or -B thanks to EqP. 3228 P = Pred; 3229 } 3230 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3231 // Cases correspond to "max(A, B) p A". 3232 switch (P) { 3233 default: 3234 break; 3235 case CmpInst::ICMP_EQ: 3236 case CmpInst::ICMP_SLE: 3237 // Equivalent to "A EqP B". This may be the same as the condition tested 3238 // in the max/min; if so, we can just return that. 3239 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 3240 return V; 3241 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 3242 return V; 3243 // Otherwise, see if "A EqP B" simplifies. 3244 if (MaxRecurse) 3245 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3246 return V; 3247 break; 3248 case CmpInst::ICMP_NE: 3249 case CmpInst::ICMP_SGT: { 3250 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3251 // Equivalent to "A InvEqP B". This may be the same as the condition 3252 // tested in the max/min; if so, we can just return that. 3253 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 3254 return V; 3255 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 3256 return V; 3257 // Otherwise, see if "A InvEqP B" simplifies. 3258 if (MaxRecurse) 3259 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3260 return V; 3261 break; 3262 } 3263 case CmpInst::ICMP_SGE: 3264 // Always true. 3265 return getTrue(ITy); 3266 case CmpInst::ICMP_SLT: 3267 // Always false. 3268 return getFalse(ITy); 3269 } 3270 } 3271 3272 // Unsigned variants on "max(a,b)>=a -> true". 3273 P = CmpInst::BAD_ICMP_PREDICATE; 3274 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3275 if (A != RHS) 3276 std::swap(A, B); // umax(A, B) pred A. 3277 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3278 // We analyze this as umax(A, B) pred A. 3279 P = Pred; 3280 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 3281 (A == LHS || B == LHS)) { 3282 if (A != LHS) 3283 std::swap(A, B); // A pred umax(A, B). 3284 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3285 // We analyze this as umax(A, B) swapped-pred A. 3286 P = CmpInst::getSwappedPredicate(Pred); 3287 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 3288 (A == RHS || B == RHS)) { 3289 if (A != RHS) 3290 std::swap(A, B); // umin(A, B) pred A. 3291 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3292 // We analyze this as umax(-A, -B) swapped-pred -A. 3293 // Note that we do not need to actually form -A or -B thanks to EqP. 3294 P = CmpInst::getSwappedPredicate(Pred); 3295 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 3296 (A == LHS || B == LHS)) { 3297 if (A != LHS) 3298 std::swap(A, B); // A pred umin(A, B). 3299 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3300 // We analyze this as umax(-A, -B) pred -A. 3301 // Note that we do not need to actually form -A or -B thanks to EqP. 3302 P = Pred; 3303 } 3304 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3305 // Cases correspond to "max(A, B) p A". 3306 switch (P) { 3307 default: 3308 break; 3309 case CmpInst::ICMP_EQ: 3310 case CmpInst::ICMP_ULE: 3311 // Equivalent to "A EqP B". This may be the same as the condition tested 3312 // in the max/min; if so, we can just return that. 3313 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 3314 return V; 3315 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 3316 return V; 3317 // Otherwise, see if "A EqP B" simplifies. 3318 if (MaxRecurse) 3319 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3320 return V; 3321 break; 3322 case CmpInst::ICMP_NE: 3323 case CmpInst::ICMP_UGT: { 3324 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3325 // Equivalent to "A InvEqP B". This may be the same as the condition 3326 // tested in the max/min; if so, we can just return that. 3327 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 3328 return V; 3329 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 3330 return V; 3331 // Otherwise, see if "A InvEqP B" simplifies. 3332 if (MaxRecurse) 3333 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3334 return V; 3335 break; 3336 } 3337 case CmpInst::ICMP_UGE: 3338 return getTrue(ITy); 3339 case CmpInst::ICMP_ULT: 3340 return getFalse(ITy); 3341 } 3342 } 3343 3344 // Comparing 1 each of min/max with a common operand? 3345 // Canonicalize min operand to RHS. 3346 if (match(LHS, m_UMin(m_Value(), m_Value())) || 3347 match(LHS, m_SMin(m_Value(), m_Value()))) { 3348 std::swap(LHS, RHS); 3349 Pred = ICmpInst::getSwappedPredicate(Pred); 3350 } 3351 3352 Value *C, *D; 3353 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 3354 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 3355 (A == C || A == D || B == C || B == D)) { 3356 // smax(A, B) >=s smin(A, D) --> true 3357 if (Pred == CmpInst::ICMP_SGE) 3358 return getTrue(ITy); 3359 // smax(A, B) <s smin(A, D) --> false 3360 if (Pred == CmpInst::ICMP_SLT) 3361 return getFalse(ITy); 3362 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 3363 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 3364 (A == C || A == D || B == C || B == D)) { 3365 // umax(A, B) >=u umin(A, D) --> true 3366 if (Pred == CmpInst::ICMP_UGE) 3367 return getTrue(ITy); 3368 // umax(A, B) <u umin(A, D) --> false 3369 if (Pred == CmpInst::ICMP_ULT) 3370 return getFalse(ITy); 3371 } 3372 3373 return nullptr; 3374 } 3375 3376 static Value *simplifyICmpWithDominatingAssume(CmpInst::Predicate Predicate, 3377 Value *LHS, Value *RHS, 3378 const SimplifyQuery &Q) { 3379 // Gracefully handle instructions that have not been inserted yet. 3380 if (!Q.AC || !Q.CxtI || !Q.CxtI->getParent()) 3381 return nullptr; 3382 3383 for (Value *AssumeBaseOp : {LHS, RHS}) { 3384 for (auto &AssumeVH : Q.AC->assumptionsFor(AssumeBaseOp)) { 3385 if (!AssumeVH) 3386 continue; 3387 3388 CallInst *Assume = cast<CallInst>(AssumeVH); 3389 if (Optional<bool> Imp = 3390 isImpliedCondition(Assume->getArgOperand(0), Predicate, LHS, RHS, 3391 Q.DL)) 3392 if (isValidAssumeForContext(Assume, Q.CxtI, Q.DT)) 3393 return ConstantInt::get(GetCompareTy(LHS), *Imp); 3394 } 3395 } 3396 3397 return nullptr; 3398 } 3399 3400 /// Given operands for an ICmpInst, see if we can fold the result. 3401 /// If not, this returns null. 3402 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3403 const SimplifyQuery &Q, unsigned MaxRecurse) { 3404 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 3405 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 3406 3407 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 3408 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 3409 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); 3410 3411 // If we have a constant, make sure it is on the RHS. 3412 std::swap(LHS, RHS); 3413 Pred = CmpInst::getSwappedPredicate(Pred); 3414 } 3415 assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X"); 3416 3417 Type *ITy = GetCompareTy(LHS); // The return type. 3418 3419 // For EQ and NE, we can always pick a value for the undef to make the 3420 // predicate pass or fail, so we can return undef. 3421 // Matches behavior in llvm::ConstantFoldCompareInstruction. 3422 if (Q.isUndefValue(RHS) && ICmpInst::isEquality(Pred)) 3423 return UndefValue::get(ITy); 3424 3425 // icmp X, X -> true/false 3426 // icmp X, undef -> true/false because undef could be X. 3427 if (LHS == RHS || Q.isUndefValue(RHS)) 3428 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 3429 3430 if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q)) 3431 return V; 3432 3433 if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q)) 3434 return V; 3435 3436 if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ)) 3437 return V; 3438 3439 // If both operands have range metadata, use the metadata 3440 // to simplify the comparison. 3441 if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) { 3442 auto RHS_Instr = cast<Instruction>(RHS); 3443 auto LHS_Instr = cast<Instruction>(LHS); 3444 3445 if (Q.IIQ.getMetadata(RHS_Instr, LLVMContext::MD_range) && 3446 Q.IIQ.getMetadata(LHS_Instr, LLVMContext::MD_range)) { 3447 auto RHS_CR = getConstantRangeFromMetadata( 3448 *RHS_Instr->getMetadata(LLVMContext::MD_range)); 3449 auto LHS_CR = getConstantRangeFromMetadata( 3450 *LHS_Instr->getMetadata(LLVMContext::MD_range)); 3451 3452 auto Satisfied_CR = ConstantRange::makeSatisfyingICmpRegion(Pred, RHS_CR); 3453 if (Satisfied_CR.contains(LHS_CR)) 3454 return ConstantInt::getTrue(RHS->getContext()); 3455 3456 auto InversedSatisfied_CR = ConstantRange::makeSatisfyingICmpRegion( 3457 CmpInst::getInversePredicate(Pred), RHS_CR); 3458 if (InversedSatisfied_CR.contains(LHS_CR)) 3459 return ConstantInt::getFalse(RHS->getContext()); 3460 } 3461 } 3462 3463 // Compare of cast, for example (zext X) != 0 -> X != 0 3464 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 3465 Instruction *LI = cast<CastInst>(LHS); 3466 Value *SrcOp = LI->getOperand(0); 3467 Type *SrcTy = SrcOp->getType(); 3468 Type *DstTy = LI->getType(); 3469 3470 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 3471 // if the integer type is the same size as the pointer type. 3472 if (MaxRecurse && isa<PtrToIntInst>(LI) && 3473 Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) { 3474 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 3475 // Transfer the cast to the constant. 3476 if (Value *V = SimplifyICmpInst(Pred, SrcOp, 3477 ConstantExpr::getIntToPtr(RHSC, SrcTy), 3478 Q, MaxRecurse-1)) 3479 return V; 3480 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 3481 if (RI->getOperand(0)->getType() == SrcTy) 3482 // Compare without the cast. 3483 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 3484 Q, MaxRecurse-1)) 3485 return V; 3486 } 3487 } 3488 3489 if (isa<ZExtInst>(LHS)) { 3490 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 3491 // same type. 3492 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3493 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3494 // Compare X and Y. Note that signed predicates become unsigned. 3495 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 3496 SrcOp, RI->getOperand(0), Q, 3497 MaxRecurse-1)) 3498 return V; 3499 } 3500 // Fold (zext X) ule (sext X), (zext X) sge (sext X) to true. 3501 else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3502 if (SrcOp == RI->getOperand(0)) { 3503 if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE) 3504 return ConstantInt::getTrue(ITy); 3505 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT) 3506 return ConstantInt::getFalse(ITy); 3507 } 3508 } 3509 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 3510 // too. If not, then try to deduce the result of the comparison. 3511 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 3512 // Compute the constant that would happen if we truncated to SrcTy then 3513 // reextended to DstTy. 3514 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 3515 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy); 3516 3517 // If the re-extended constant didn't change then this is effectively 3518 // also a case of comparing two zero-extended values. 3519 if (RExt == CI && MaxRecurse) 3520 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 3521 SrcOp, Trunc, Q, MaxRecurse-1)) 3522 return V; 3523 3524 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 3525 // there. Use this to work out the result of the comparison. 3526 if (RExt != CI) { 3527 switch (Pred) { 3528 default: llvm_unreachable("Unknown ICmp predicate!"); 3529 // LHS <u RHS. 3530 case ICmpInst::ICMP_EQ: 3531 case ICmpInst::ICMP_UGT: 3532 case ICmpInst::ICMP_UGE: 3533 return ConstantInt::getFalse(CI->getContext()); 3534 3535 case ICmpInst::ICMP_NE: 3536 case ICmpInst::ICMP_ULT: 3537 case ICmpInst::ICMP_ULE: 3538 return ConstantInt::getTrue(CI->getContext()); 3539 3540 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 3541 // is non-negative then LHS <s RHS. 3542 case ICmpInst::ICMP_SGT: 3543 case ICmpInst::ICMP_SGE: 3544 return CI->getValue().isNegative() ? 3545 ConstantInt::getTrue(CI->getContext()) : 3546 ConstantInt::getFalse(CI->getContext()); 3547 3548 case ICmpInst::ICMP_SLT: 3549 case ICmpInst::ICMP_SLE: 3550 return CI->getValue().isNegative() ? 3551 ConstantInt::getFalse(CI->getContext()) : 3552 ConstantInt::getTrue(CI->getContext()); 3553 } 3554 } 3555 } 3556 } 3557 3558 if (isa<SExtInst>(LHS)) { 3559 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 3560 // same type. 3561 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3562 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3563 // Compare X and Y. Note that the predicate does not change. 3564 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 3565 Q, MaxRecurse-1)) 3566 return V; 3567 } 3568 // Fold (sext X) uge (zext X), (sext X) sle (zext X) to true. 3569 else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3570 if (SrcOp == RI->getOperand(0)) { 3571 if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE) 3572 return ConstantInt::getTrue(ITy); 3573 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT) 3574 return ConstantInt::getFalse(ITy); 3575 } 3576 } 3577 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 3578 // too. If not, then try to deduce the result of the comparison. 3579 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 3580 // Compute the constant that would happen if we truncated to SrcTy then 3581 // reextended to DstTy. 3582 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 3583 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy); 3584 3585 // If the re-extended constant didn't change then this is effectively 3586 // also a case of comparing two sign-extended values. 3587 if (RExt == CI && MaxRecurse) 3588 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1)) 3589 return V; 3590 3591 // Otherwise the upper bits of LHS are all equal, while RHS has varying 3592 // bits there. Use this to work out the result of the comparison. 3593 if (RExt != CI) { 3594 switch (Pred) { 3595 default: llvm_unreachable("Unknown ICmp predicate!"); 3596 case ICmpInst::ICMP_EQ: 3597 return ConstantInt::getFalse(CI->getContext()); 3598 case ICmpInst::ICMP_NE: 3599 return ConstantInt::getTrue(CI->getContext()); 3600 3601 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 3602 // LHS >s RHS. 3603 case ICmpInst::ICMP_SGT: 3604 case ICmpInst::ICMP_SGE: 3605 return CI->getValue().isNegative() ? 3606 ConstantInt::getTrue(CI->getContext()) : 3607 ConstantInt::getFalse(CI->getContext()); 3608 case ICmpInst::ICMP_SLT: 3609 case ICmpInst::ICMP_SLE: 3610 return CI->getValue().isNegative() ? 3611 ConstantInt::getFalse(CI->getContext()) : 3612 ConstantInt::getTrue(CI->getContext()); 3613 3614 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 3615 // LHS >u RHS. 3616 case ICmpInst::ICMP_UGT: 3617 case ICmpInst::ICMP_UGE: 3618 // Comparison is true iff the LHS <s 0. 3619 if (MaxRecurse) 3620 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 3621 Constant::getNullValue(SrcTy), 3622 Q, MaxRecurse-1)) 3623 return V; 3624 break; 3625 case ICmpInst::ICMP_ULT: 3626 case ICmpInst::ICMP_ULE: 3627 // Comparison is true iff the LHS >=s 0. 3628 if (MaxRecurse) 3629 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 3630 Constant::getNullValue(SrcTy), 3631 Q, MaxRecurse-1)) 3632 return V; 3633 break; 3634 } 3635 } 3636 } 3637 } 3638 } 3639 3640 // icmp eq|ne X, Y -> false|true if X != Y 3641 if (ICmpInst::isEquality(Pred) && 3642 isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) { 3643 return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy); 3644 } 3645 3646 if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse)) 3647 return V; 3648 3649 if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse)) 3650 return V; 3651 3652 if (Value *V = simplifyICmpWithDominatingAssume(Pred, LHS, RHS, Q)) 3653 return V; 3654 3655 // Simplify comparisons of related pointers using a powerful, recursive 3656 // GEP-walk when we have target data available.. 3657 if (LHS->getType()->isPointerTy()) 3658 if (auto *C = computePointerICmp(Pred, LHS, RHS, Q)) 3659 return C; 3660 if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS)) 3661 if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS)) 3662 if (Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) == 3663 Q.DL.getTypeSizeInBits(CLHS->getType()) && 3664 Q.DL.getTypeSizeInBits(CRHS->getPointerOperandType()) == 3665 Q.DL.getTypeSizeInBits(CRHS->getType())) 3666 if (auto *C = computePointerICmp(Pred, CLHS->getPointerOperand(), 3667 CRHS->getPointerOperand(), Q)) 3668 return C; 3669 3670 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) { 3671 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) { 3672 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() && 3673 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() && 3674 (ICmpInst::isEquality(Pred) || 3675 (GLHS->isInBounds() && GRHS->isInBounds() && 3676 Pred == ICmpInst::getSignedPredicate(Pred)))) { 3677 // The bases are equal and the indices are constant. Build a constant 3678 // expression GEP with the same indices and a null base pointer to see 3679 // what constant folding can make out of it. 3680 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType()); 3681 SmallVector<Value *, 4> IndicesLHS(GLHS->indices()); 3682 Constant *NewLHS = ConstantExpr::getGetElementPtr( 3683 GLHS->getSourceElementType(), Null, IndicesLHS); 3684 3685 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end()); 3686 Constant *NewRHS = ConstantExpr::getGetElementPtr( 3687 GLHS->getSourceElementType(), Null, IndicesRHS); 3688 Constant *NewICmp = ConstantExpr::getICmp(Pred, NewLHS, NewRHS); 3689 return ConstantFoldConstant(NewICmp, Q.DL); 3690 } 3691 } 3692 } 3693 3694 // If the comparison is with the result of a select instruction, check whether 3695 // comparing with either branch of the select always yields the same value. 3696 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 3697 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 3698 return V; 3699 3700 // If the comparison is with the result of a phi instruction, check whether 3701 // doing the compare with each incoming phi value yields a common result. 3702 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 3703 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 3704 return V; 3705 3706 return nullptr; 3707 } 3708 3709 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3710 const SimplifyQuery &Q) { 3711 return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 3712 } 3713 3714 /// Given operands for an FCmpInst, see if we can fold the result. 3715 /// If not, this returns null. 3716 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3717 FastMathFlags FMF, const SimplifyQuery &Q, 3718 unsigned MaxRecurse) { 3719 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 3720 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 3721 3722 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 3723 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 3724 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); 3725 3726 // If we have a constant, make sure it is on the RHS. 3727 std::swap(LHS, RHS); 3728 Pred = CmpInst::getSwappedPredicate(Pred); 3729 } 3730 3731 // Fold trivial predicates. 3732 Type *RetTy = GetCompareTy(LHS); 3733 if (Pred == FCmpInst::FCMP_FALSE) 3734 return getFalse(RetTy); 3735 if (Pred == FCmpInst::FCMP_TRUE) 3736 return getTrue(RetTy); 3737 3738 // Fold (un)ordered comparison if we can determine there are no NaNs. 3739 if (Pred == FCmpInst::FCMP_UNO || Pred == FCmpInst::FCMP_ORD) 3740 if (FMF.noNaNs() || 3741 (isKnownNeverNaN(LHS, Q.TLI) && isKnownNeverNaN(RHS, Q.TLI))) 3742 return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD); 3743 3744 // NaN is unordered; NaN is not ordered. 3745 assert((FCmpInst::isOrdered(Pred) || FCmpInst::isUnordered(Pred)) && 3746 "Comparison must be either ordered or unordered"); 3747 if (match(RHS, m_NaN())) 3748 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 3749 3750 // fcmp pred x, undef and fcmp pred undef, x 3751 // fold to true if unordered, false if ordered 3752 if (Q.isUndefValue(LHS) || Q.isUndefValue(RHS)) { 3753 // Choosing NaN for the undef will always make unordered comparison succeed 3754 // and ordered comparison fail. 3755 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 3756 } 3757 3758 // fcmp x,x -> true/false. Not all compares are foldable. 3759 if (LHS == RHS) { 3760 if (CmpInst::isTrueWhenEqual(Pred)) 3761 return getTrue(RetTy); 3762 if (CmpInst::isFalseWhenEqual(Pred)) 3763 return getFalse(RetTy); 3764 } 3765 3766 // Handle fcmp with constant RHS. 3767 // TODO: Use match with a specific FP value, so these work with vectors with 3768 // undef lanes. 3769 const APFloat *C; 3770 if (match(RHS, m_APFloat(C))) { 3771 // Check whether the constant is an infinity. 3772 if (C->isInfinity()) { 3773 if (C->isNegative()) { 3774 switch (Pred) { 3775 case FCmpInst::FCMP_OLT: 3776 // No value is ordered and less than negative infinity. 3777 return getFalse(RetTy); 3778 case FCmpInst::FCMP_UGE: 3779 // All values are unordered with or at least negative infinity. 3780 return getTrue(RetTy); 3781 default: 3782 break; 3783 } 3784 } else { 3785 switch (Pred) { 3786 case FCmpInst::FCMP_OGT: 3787 // No value is ordered and greater than infinity. 3788 return getFalse(RetTy); 3789 case FCmpInst::FCMP_ULE: 3790 // All values are unordered with and at most infinity. 3791 return getTrue(RetTy); 3792 default: 3793 break; 3794 } 3795 } 3796 3797 // LHS == Inf 3798 if (Pred == FCmpInst::FCMP_OEQ && isKnownNeverInfinity(LHS, Q.TLI)) 3799 return getFalse(RetTy); 3800 // LHS != Inf 3801 if (Pred == FCmpInst::FCMP_UNE && isKnownNeverInfinity(LHS, Q.TLI)) 3802 return getTrue(RetTy); 3803 // LHS == Inf || LHS == NaN 3804 if (Pred == FCmpInst::FCMP_UEQ && isKnownNeverInfinity(LHS, Q.TLI) && 3805 isKnownNeverNaN(LHS, Q.TLI)) 3806 return getFalse(RetTy); 3807 // LHS != Inf && LHS != NaN 3808 if (Pred == FCmpInst::FCMP_ONE && isKnownNeverInfinity(LHS, Q.TLI) && 3809 isKnownNeverNaN(LHS, Q.TLI)) 3810 return getTrue(RetTy); 3811 } 3812 if (C->isNegative() && !C->isNegZero()) { 3813 assert(!C->isNaN() && "Unexpected NaN constant!"); 3814 // TODO: We can catch more cases by using a range check rather than 3815 // relying on CannotBeOrderedLessThanZero. 3816 switch (Pred) { 3817 case FCmpInst::FCMP_UGE: 3818 case FCmpInst::FCMP_UGT: 3819 case FCmpInst::FCMP_UNE: 3820 // (X >= 0) implies (X > C) when (C < 0) 3821 if (CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3822 return getTrue(RetTy); 3823 break; 3824 case FCmpInst::FCMP_OEQ: 3825 case FCmpInst::FCMP_OLE: 3826 case FCmpInst::FCMP_OLT: 3827 // (X >= 0) implies !(X < C) when (C < 0) 3828 if (CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3829 return getFalse(RetTy); 3830 break; 3831 default: 3832 break; 3833 } 3834 } 3835 3836 // Check comparison of [minnum/maxnum with constant] with other constant. 3837 const APFloat *C2; 3838 if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) && 3839 *C2 < *C) || 3840 (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) && 3841 *C2 > *C)) { 3842 bool IsMaxNum = 3843 cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum; 3844 // The ordered relationship and minnum/maxnum guarantee that we do not 3845 // have NaN constants, so ordered/unordered preds are handled the same. 3846 switch (Pred) { 3847 case FCmpInst::FCMP_OEQ: case FCmpInst::FCMP_UEQ: 3848 // minnum(X, LesserC) == C --> false 3849 // maxnum(X, GreaterC) == C --> false 3850 return getFalse(RetTy); 3851 case FCmpInst::FCMP_ONE: case FCmpInst::FCMP_UNE: 3852 // minnum(X, LesserC) != C --> true 3853 // maxnum(X, GreaterC) != C --> true 3854 return getTrue(RetTy); 3855 case FCmpInst::FCMP_OGE: case FCmpInst::FCMP_UGE: 3856 case FCmpInst::FCMP_OGT: case FCmpInst::FCMP_UGT: 3857 // minnum(X, LesserC) >= C --> false 3858 // minnum(X, LesserC) > C --> false 3859 // maxnum(X, GreaterC) >= C --> true 3860 // maxnum(X, GreaterC) > C --> true 3861 return ConstantInt::get(RetTy, IsMaxNum); 3862 case FCmpInst::FCMP_OLE: case FCmpInst::FCMP_ULE: 3863 case FCmpInst::FCMP_OLT: case FCmpInst::FCMP_ULT: 3864 // minnum(X, LesserC) <= C --> true 3865 // minnum(X, LesserC) < C --> true 3866 // maxnum(X, GreaterC) <= C --> false 3867 // maxnum(X, GreaterC) < C --> false 3868 return ConstantInt::get(RetTy, !IsMaxNum); 3869 default: 3870 // TRUE/FALSE/ORD/UNO should be handled before this. 3871 llvm_unreachable("Unexpected fcmp predicate"); 3872 } 3873 } 3874 } 3875 3876 if (match(RHS, m_AnyZeroFP())) { 3877 switch (Pred) { 3878 case FCmpInst::FCMP_OGE: 3879 case FCmpInst::FCMP_ULT: 3880 // Positive or zero X >= 0.0 --> true 3881 // Positive or zero X < 0.0 --> false 3882 if ((FMF.noNaNs() || isKnownNeverNaN(LHS, Q.TLI)) && 3883 CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3884 return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy); 3885 break; 3886 case FCmpInst::FCMP_UGE: 3887 case FCmpInst::FCMP_OLT: 3888 // Positive or zero or nan X >= 0.0 --> true 3889 // Positive or zero or nan X < 0.0 --> false 3890 if (CannotBeOrderedLessThanZero(LHS, Q.TLI)) 3891 return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy); 3892 break; 3893 default: 3894 break; 3895 } 3896 } 3897 3898 // If the comparison is with the result of a select instruction, check whether 3899 // comparing with either branch of the select always yields the same value. 3900 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 3901 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 3902 return V; 3903 3904 // If the comparison is with the result of a phi instruction, check whether 3905 // doing the compare with each incoming phi value yields a common result. 3906 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 3907 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 3908 return V; 3909 3910 return nullptr; 3911 } 3912 3913 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3914 FastMathFlags FMF, const SimplifyQuery &Q) { 3915 return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit); 3916 } 3917 3918 static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 3919 const SimplifyQuery &Q, 3920 bool AllowRefinement, 3921 unsigned MaxRecurse) { 3922 // Trivial replacement. 3923 if (V == Op) 3924 return RepOp; 3925 3926 // We cannot replace a constant, and shouldn't even try. 3927 if (isa<Constant>(Op)) 3928 return nullptr; 3929 3930 auto *I = dyn_cast<Instruction>(V); 3931 if (!I) 3932 return nullptr; 3933 3934 // Consider: 3935 // %cmp = icmp eq i32 %x, 2147483647 3936 // %add = add nsw i32 %x, 1 3937 // %sel = select i1 %cmp, i32 -2147483648, i32 %add 3938 // 3939 // We can't replace %sel with %add unless we strip away the flags (which will 3940 // be done in InstCombine). 3941 // TODO: This is unsound, because it only catches some forms of refinement. 3942 if (!AllowRefinement && canCreatePoison(cast<Operator>(I))) 3943 return nullptr; 3944 3945 // The simplification queries below may return the original value. Consider: 3946 // %div = udiv i32 %arg, %arg2 3947 // %mul = mul nsw i32 %div, %arg2 3948 // %cmp = icmp eq i32 %mul, %arg 3949 // %sel = select i1 %cmp, i32 %div, i32 undef 3950 // Replacing %arg by %mul, %div becomes "udiv i32 %mul, %arg2", which 3951 // simplifies back to %arg. This can only happen because %mul does not 3952 // dominate %div. To ensure a consistent return value contract, we make sure 3953 // that this case returns nullptr as well. 3954 auto PreventSelfSimplify = [V](Value *Simplified) { 3955 return Simplified != V ? Simplified : nullptr; 3956 }; 3957 3958 // If this is a binary operator, try to simplify it with the replaced op. 3959 if (auto *B = dyn_cast<BinaryOperator>(I)) { 3960 if (MaxRecurse) { 3961 if (B->getOperand(0) == Op) 3962 return PreventSelfSimplify(SimplifyBinOp(B->getOpcode(), RepOp, 3963 B->getOperand(1), Q, 3964 MaxRecurse - 1)); 3965 if (B->getOperand(1) == Op) 3966 return PreventSelfSimplify(SimplifyBinOp(B->getOpcode(), 3967 B->getOperand(0), RepOp, Q, 3968 MaxRecurse - 1)); 3969 } 3970 } 3971 3972 // Same for CmpInsts. 3973 if (CmpInst *C = dyn_cast<CmpInst>(I)) { 3974 if (MaxRecurse) { 3975 if (C->getOperand(0) == Op) 3976 return PreventSelfSimplify(SimplifyCmpInst(C->getPredicate(), RepOp, 3977 C->getOperand(1), Q, 3978 MaxRecurse - 1)); 3979 if (C->getOperand(1) == Op) 3980 return PreventSelfSimplify(SimplifyCmpInst(C->getPredicate(), 3981 C->getOperand(0), RepOp, Q, 3982 MaxRecurse - 1)); 3983 } 3984 } 3985 3986 // Same for GEPs. 3987 if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) { 3988 if (MaxRecurse) { 3989 SmallVector<Value *, 8> NewOps(GEP->getNumOperands()); 3990 transform(GEP->operands(), NewOps.begin(), 3991 [&](Value *V) { return V == Op ? RepOp : V; }); 3992 return PreventSelfSimplify(SimplifyGEPInst(GEP->getSourceElementType(), 3993 NewOps, Q, MaxRecurse - 1)); 3994 } 3995 } 3996 3997 // TODO: We could hand off more cases to instsimplify here. 3998 3999 // If all operands are constant after substituting Op for RepOp then we can 4000 // constant fold the instruction. 4001 if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) { 4002 // Build a list of all constant operands. 4003 SmallVector<Constant *, 8> ConstOps; 4004 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { 4005 if (I->getOperand(i) == Op) 4006 ConstOps.push_back(CRepOp); 4007 else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i))) 4008 ConstOps.push_back(COp); 4009 else 4010 break; 4011 } 4012 4013 // All operands were constants, fold it. 4014 if (ConstOps.size() == I->getNumOperands()) { 4015 if (CmpInst *C = dyn_cast<CmpInst>(I)) 4016 return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0], 4017 ConstOps[1], Q.DL, Q.TLI); 4018 4019 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 4020 if (!LI->isVolatile()) 4021 return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL); 4022 4023 return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI); 4024 } 4025 } 4026 4027 return nullptr; 4028 } 4029 4030 Value *llvm::SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 4031 const SimplifyQuery &Q, 4032 bool AllowRefinement) { 4033 return ::SimplifyWithOpReplaced(V, Op, RepOp, Q, AllowRefinement, 4034 RecursionLimit); 4035 } 4036 4037 /// Try to simplify a select instruction when its condition operand is an 4038 /// integer comparison where one operand of the compare is a constant. 4039 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X, 4040 const APInt *Y, bool TrueWhenUnset) { 4041 const APInt *C; 4042 4043 // (X & Y) == 0 ? X & ~Y : X --> X 4044 // (X & Y) != 0 ? X & ~Y : X --> X & ~Y 4045 if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) && 4046 *Y == ~*C) 4047 return TrueWhenUnset ? FalseVal : TrueVal; 4048 4049 // (X & Y) == 0 ? X : X & ~Y --> X & ~Y 4050 // (X & Y) != 0 ? X : X & ~Y --> X 4051 if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) && 4052 *Y == ~*C) 4053 return TrueWhenUnset ? FalseVal : TrueVal; 4054 4055 if (Y->isPowerOf2()) { 4056 // (X & Y) == 0 ? X | Y : X --> X | Y 4057 // (X & Y) != 0 ? X | Y : X --> X 4058 if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) && 4059 *Y == *C) 4060 return TrueWhenUnset ? TrueVal : FalseVal; 4061 4062 // (X & Y) == 0 ? X : X | Y --> X 4063 // (X & Y) != 0 ? X : X | Y --> X | Y 4064 if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) && 4065 *Y == *C) 4066 return TrueWhenUnset ? TrueVal : FalseVal; 4067 } 4068 4069 return nullptr; 4070 } 4071 4072 /// An alternative way to test if a bit is set or not uses sgt/slt instead of 4073 /// eq/ne. 4074 static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS, 4075 ICmpInst::Predicate Pred, 4076 Value *TrueVal, Value *FalseVal) { 4077 Value *X; 4078 APInt Mask; 4079 if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) 4080 return nullptr; 4081 4082 return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask, 4083 Pred == ICmpInst::ICMP_EQ); 4084 } 4085 4086 /// Try to simplify a select instruction when its condition operand is an 4087 /// integer comparison. 4088 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, 4089 Value *FalseVal, const SimplifyQuery &Q, 4090 unsigned MaxRecurse) { 4091 ICmpInst::Predicate Pred; 4092 Value *CmpLHS, *CmpRHS; 4093 if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS)))) 4094 return nullptr; 4095 4096 // Canonicalize ne to eq predicate. 4097 if (Pred == ICmpInst::ICMP_NE) { 4098 Pred = ICmpInst::ICMP_EQ; 4099 std::swap(TrueVal, FalseVal); 4100 } 4101 4102 if (Pred == ICmpInst::ICMP_EQ && match(CmpRHS, m_Zero())) { 4103 Value *X; 4104 const APInt *Y; 4105 if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y)))) 4106 if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y, 4107 /*TrueWhenUnset=*/true)) 4108 return V; 4109 4110 // Test for a bogus zero-shift-guard-op around funnel-shift or rotate. 4111 Value *ShAmt; 4112 auto isFsh = m_CombineOr(m_FShl(m_Value(X), m_Value(), m_Value(ShAmt)), 4113 m_FShr(m_Value(), m_Value(X), m_Value(ShAmt))); 4114 // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X 4115 // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X 4116 if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt) 4117 return X; 4118 4119 // Test for a zero-shift-guard-op around rotates. These are used to 4120 // avoid UB from oversized shifts in raw IR rotate patterns, but the 4121 // intrinsics do not have that problem. 4122 // We do not allow this transform for the general funnel shift case because 4123 // that would not preserve the poison safety of the original code. 4124 auto isRotate = 4125 m_CombineOr(m_FShl(m_Value(X), m_Deferred(X), m_Value(ShAmt)), 4126 m_FShr(m_Value(X), m_Deferred(X), m_Value(ShAmt))); 4127 // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt) 4128 // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt) 4129 if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt && 4130 Pred == ICmpInst::ICMP_EQ) 4131 return FalseVal; 4132 4133 // X == 0 ? abs(X) : -abs(X) --> -abs(X) 4134 // X == 0 ? -abs(X) : abs(X) --> abs(X) 4135 if (match(TrueVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))) && 4136 match(FalseVal, m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))))) 4137 return FalseVal; 4138 if (match(TrueVal, 4139 m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) && 4140 match(FalseVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) 4141 return FalseVal; 4142 } 4143 4144 // Check for other compares that behave like bit test. 4145 if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred, 4146 TrueVal, FalseVal)) 4147 return V; 4148 4149 // If we have an equality comparison, then we know the value in one of the 4150 // arms of the select. See if substituting this value into the arm and 4151 // simplifying the result yields the same value as the other arm. 4152 if (Pred == ICmpInst::ICMP_EQ) { 4153 if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, 4154 /* AllowRefinement */ false, MaxRecurse) == 4155 TrueVal || 4156 SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, 4157 /* AllowRefinement */ false, MaxRecurse) == 4158 TrueVal) 4159 return FalseVal; 4160 if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, 4161 /* AllowRefinement */ true, MaxRecurse) == 4162 FalseVal || 4163 SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, 4164 /* AllowRefinement */ true, MaxRecurse) == 4165 FalseVal) 4166 return FalseVal; 4167 } 4168 4169 return nullptr; 4170 } 4171 4172 /// Try to simplify a select instruction when its condition operand is a 4173 /// floating-point comparison. 4174 static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F, 4175 const SimplifyQuery &Q) { 4176 FCmpInst::Predicate Pred; 4177 if (!match(Cond, m_FCmp(Pred, m_Specific(T), m_Specific(F))) && 4178 !match(Cond, m_FCmp(Pred, m_Specific(F), m_Specific(T)))) 4179 return nullptr; 4180 4181 // This transform is safe if we do not have (do not care about) -0.0 or if 4182 // at least one operand is known to not be -0.0. Otherwise, the select can 4183 // change the sign of a zero operand. 4184 bool HasNoSignedZeros = Q.CxtI && isa<FPMathOperator>(Q.CxtI) && 4185 Q.CxtI->hasNoSignedZeros(); 4186 const APFloat *C; 4187 if (HasNoSignedZeros || (match(T, m_APFloat(C)) && C->isNonZero()) || 4188 (match(F, m_APFloat(C)) && C->isNonZero())) { 4189 // (T == F) ? T : F --> F 4190 // (F == T) ? T : F --> F 4191 if (Pred == FCmpInst::FCMP_OEQ) 4192 return F; 4193 4194 // (T != F) ? T : F --> T 4195 // (F != T) ? T : F --> T 4196 if (Pred == FCmpInst::FCMP_UNE) 4197 return T; 4198 } 4199 4200 return nullptr; 4201 } 4202 4203 /// Given operands for a SelectInst, see if we can fold the result. 4204 /// If not, this returns null. 4205 static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4206 const SimplifyQuery &Q, unsigned MaxRecurse) { 4207 if (auto *CondC = dyn_cast<Constant>(Cond)) { 4208 if (auto *TrueC = dyn_cast<Constant>(TrueVal)) 4209 if (auto *FalseC = dyn_cast<Constant>(FalseVal)) 4210 return ConstantFoldSelectInstruction(CondC, TrueC, FalseC); 4211 4212 // select undef, X, Y -> X or Y 4213 if (Q.isUndefValue(CondC)) 4214 return isa<Constant>(FalseVal) ? FalseVal : TrueVal; 4215 4216 // TODO: Vector constants with undef elements don't simplify. 4217 4218 // select true, X, Y -> X 4219 if (CondC->isAllOnesValue()) 4220 return TrueVal; 4221 // select false, X, Y -> Y 4222 if (CondC->isNullValue()) 4223 return FalseVal; 4224 } 4225 4226 // select i1 Cond, i1 true, i1 false --> i1 Cond 4227 assert(Cond->getType()->isIntOrIntVectorTy(1) && 4228 "Select must have bool or bool vector condition"); 4229 assert(TrueVal->getType() == FalseVal->getType() && 4230 "Select must have same types for true/false ops"); 4231 if (Cond->getType() == TrueVal->getType() && 4232 match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt())) 4233 return Cond; 4234 4235 // select ?, X, X -> X 4236 if (TrueVal == FalseVal) 4237 return TrueVal; 4238 4239 // If the true or false value is undef, we can fold to the other value as 4240 // long as the other value isn't poison. 4241 // select ?, undef, X -> X 4242 if (Q.isUndefValue(TrueVal) && 4243 isGuaranteedNotToBeUndefOrPoison(FalseVal, Q.AC, Q.CxtI, Q.DT)) 4244 return FalseVal; 4245 // select ?, X, undef -> X 4246 if (Q.isUndefValue(FalseVal) && 4247 isGuaranteedNotToBeUndefOrPoison(TrueVal, Q.AC, Q.CxtI, Q.DT)) 4248 return TrueVal; 4249 4250 // Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC'' 4251 Constant *TrueC, *FalseC; 4252 if (isa<FixedVectorType>(TrueVal->getType()) && 4253 match(TrueVal, m_Constant(TrueC)) && 4254 match(FalseVal, m_Constant(FalseC))) { 4255 unsigned NumElts = 4256 cast<FixedVectorType>(TrueC->getType())->getNumElements(); 4257 SmallVector<Constant *, 16> NewC; 4258 for (unsigned i = 0; i != NumElts; ++i) { 4259 // Bail out on incomplete vector constants. 4260 Constant *TEltC = TrueC->getAggregateElement(i); 4261 Constant *FEltC = FalseC->getAggregateElement(i); 4262 if (!TEltC || !FEltC) 4263 break; 4264 4265 // If the elements match (undef or not), that value is the result. If only 4266 // one element is undef, choose the defined element as the safe result. 4267 if (TEltC == FEltC) 4268 NewC.push_back(TEltC); 4269 else if (Q.isUndefValue(TEltC) && 4270 isGuaranteedNotToBeUndefOrPoison(FEltC)) 4271 NewC.push_back(FEltC); 4272 else if (Q.isUndefValue(FEltC) && 4273 isGuaranteedNotToBeUndefOrPoison(TEltC)) 4274 NewC.push_back(TEltC); 4275 else 4276 break; 4277 } 4278 if (NewC.size() == NumElts) 4279 return ConstantVector::get(NewC); 4280 } 4281 4282 if (Value *V = 4283 simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse)) 4284 return V; 4285 4286 if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q)) 4287 return V; 4288 4289 if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal)) 4290 return V; 4291 4292 Optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL); 4293 if (Imp) 4294 return *Imp ? TrueVal : FalseVal; 4295 4296 return nullptr; 4297 } 4298 4299 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4300 const SimplifyQuery &Q) { 4301 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit); 4302 } 4303 4304 /// Given operands for an GetElementPtrInst, see if we can fold the result. 4305 /// If not, this returns null. 4306 static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, 4307 const SimplifyQuery &Q, unsigned) { 4308 // The type of the GEP pointer operand. 4309 unsigned AS = 4310 cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace(); 4311 4312 // getelementptr P -> P. 4313 if (Ops.size() == 1) 4314 return Ops[0]; 4315 4316 // Compute the (pointer) type returned by the GEP instruction. 4317 Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1)); 4318 Type *GEPTy = PointerType::get(LastType, AS); 4319 if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType())) 4320 GEPTy = VectorType::get(GEPTy, VT->getElementCount()); 4321 else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType())) 4322 GEPTy = VectorType::get(GEPTy, VT->getElementCount()); 4323 4324 // getelementptr poison, idx -> poison 4325 // getelementptr baseptr, poison -> poison 4326 if (any_of(Ops, [](const auto *V) { return isa<PoisonValue>(V); })) 4327 return PoisonValue::get(GEPTy); 4328 4329 if (Q.isUndefValue(Ops[0])) 4330 return UndefValue::get(GEPTy); 4331 4332 bool IsScalableVec = isa<ScalableVectorType>(SrcTy); 4333 4334 if (Ops.size() == 2) { 4335 // getelementptr P, 0 -> P. 4336 if (match(Ops[1], m_Zero()) && Ops[0]->getType() == GEPTy) 4337 return Ops[0]; 4338 4339 Type *Ty = SrcTy; 4340 if (!IsScalableVec && Ty->isSized()) { 4341 Value *P; 4342 uint64_t C; 4343 uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty); 4344 // getelementptr P, N -> P if P points to a type of zero size. 4345 if (TyAllocSize == 0 && Ops[0]->getType() == GEPTy) 4346 return Ops[0]; 4347 4348 // The following transforms are only safe if the ptrtoint cast 4349 // doesn't truncate the pointers. 4350 if (Ops[1]->getType()->getScalarSizeInBits() == 4351 Q.DL.getPointerSizeInBits(AS)) { 4352 auto PtrToInt = [GEPTy](Value *P) -> Value * { 4353 Value *Temp; 4354 if (match(P, m_PtrToInt(m_Value(Temp)))) 4355 if (Temp->getType() == GEPTy) 4356 return Temp; 4357 return nullptr; 4358 }; 4359 4360 // FIXME: The following transforms are only legal if P and V have the 4361 // same provenance (PR44403). Check whether getUnderlyingObject() is 4362 // the same? 4363 4364 // getelementptr V, (sub P, V) -> P if P points to a type of size 1. 4365 if (TyAllocSize == 1 && 4366 match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))))) 4367 if (Value *R = PtrToInt(P)) 4368 return R; 4369 4370 // getelementptr V, (ashr (sub P, V), C) -> Q 4371 // if P points to a type of size 1 << C. 4372 if (match(Ops[1], 4373 m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))), 4374 m_ConstantInt(C))) && 4375 TyAllocSize == 1ULL << C) 4376 if (Value *R = PtrToInt(P)) 4377 return R; 4378 4379 // getelementptr V, (sdiv (sub P, V), C) -> Q 4380 // if P points to a type of size C. 4381 if (match(Ops[1], 4382 m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))), 4383 m_SpecificInt(TyAllocSize)))) 4384 if (Value *R = PtrToInt(P)) 4385 return R; 4386 } 4387 } 4388 } 4389 4390 if (!IsScalableVec && Q.DL.getTypeAllocSize(LastType) == 1 && 4391 all_of(Ops.slice(1).drop_back(1), 4392 [](Value *Idx) { return match(Idx, m_Zero()); })) { 4393 unsigned IdxWidth = 4394 Q.DL.getIndexSizeInBits(Ops[0]->getType()->getPointerAddressSpace()); 4395 if (Q.DL.getTypeSizeInBits(Ops.back()->getType()) == IdxWidth) { 4396 APInt BasePtrOffset(IdxWidth, 0); 4397 Value *StrippedBasePtr = 4398 Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL, 4399 BasePtrOffset); 4400 4401 // Avoid creating inttoptr of zero here: While LLVMs treatment of 4402 // inttoptr is generally conservative, this particular case is folded to 4403 // a null pointer, which will have incorrect provenance. 4404 4405 // gep (gep V, C), (sub 0, V) -> C 4406 if (match(Ops.back(), 4407 m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr)))) && 4408 !BasePtrOffset.isNullValue()) { 4409 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset); 4410 return ConstantExpr::getIntToPtr(CI, GEPTy); 4411 } 4412 // gep (gep V, C), (xor V, -1) -> C-1 4413 if (match(Ops.back(), 4414 m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes())) && 4415 !BasePtrOffset.isOneValue()) { 4416 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1); 4417 return ConstantExpr::getIntToPtr(CI, GEPTy); 4418 } 4419 } 4420 } 4421 4422 // Check to see if this is constant foldable. 4423 if (!all_of(Ops, [](Value *V) { return isa<Constant>(V); })) 4424 return nullptr; 4425 4426 auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]), 4427 Ops.slice(1)); 4428 return ConstantFoldConstant(CE, Q.DL); 4429 } 4430 4431 Value *llvm::SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, 4432 const SimplifyQuery &Q) { 4433 return ::SimplifyGEPInst(SrcTy, Ops, Q, RecursionLimit); 4434 } 4435 4436 /// Given operands for an InsertValueInst, see if we can fold the result. 4437 /// If not, this returns null. 4438 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val, 4439 ArrayRef<unsigned> Idxs, const SimplifyQuery &Q, 4440 unsigned) { 4441 if (Constant *CAgg = dyn_cast<Constant>(Agg)) 4442 if (Constant *CVal = dyn_cast<Constant>(Val)) 4443 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); 4444 4445 // insertvalue x, undef, n -> x 4446 if (Q.isUndefValue(Val)) 4447 return Agg; 4448 4449 // insertvalue x, (extractvalue y, n), n 4450 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) 4451 if (EV->getAggregateOperand()->getType() == Agg->getType() && 4452 EV->getIndices() == Idxs) { 4453 // insertvalue undef, (extractvalue y, n), n -> y 4454 if (Q.isUndefValue(Agg)) 4455 return EV->getAggregateOperand(); 4456 4457 // insertvalue y, (extractvalue y, n), n -> y 4458 if (Agg == EV->getAggregateOperand()) 4459 return Agg; 4460 } 4461 4462 return nullptr; 4463 } 4464 4465 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val, 4466 ArrayRef<unsigned> Idxs, 4467 const SimplifyQuery &Q) { 4468 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit); 4469 } 4470 4471 Value *llvm::SimplifyInsertElementInst(Value *Vec, Value *Val, Value *Idx, 4472 const SimplifyQuery &Q) { 4473 // Try to constant fold. 4474 auto *VecC = dyn_cast<Constant>(Vec); 4475 auto *ValC = dyn_cast<Constant>(Val); 4476 auto *IdxC = dyn_cast<Constant>(Idx); 4477 if (VecC && ValC && IdxC) 4478 return ConstantExpr::getInsertElement(VecC, ValC, IdxC); 4479 4480 // For fixed-length vector, fold into poison if index is out of bounds. 4481 if (auto *CI = dyn_cast<ConstantInt>(Idx)) { 4482 if (isa<FixedVectorType>(Vec->getType()) && 4483 CI->uge(cast<FixedVectorType>(Vec->getType())->getNumElements())) 4484 return PoisonValue::get(Vec->getType()); 4485 } 4486 4487 // If index is undef, it might be out of bounds (see above case) 4488 if (Q.isUndefValue(Idx)) 4489 return PoisonValue::get(Vec->getType()); 4490 4491 // If the scalar is poison, or it is undef and there is no risk of 4492 // propagating poison from the vector value, simplify to the vector value. 4493 if (isa<PoisonValue>(Val) || 4494 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Vec))) 4495 return Vec; 4496 4497 // If we are extracting a value from a vector, then inserting it into the same 4498 // place, that's the input vector: 4499 // insertelt Vec, (extractelt Vec, Idx), Idx --> Vec 4500 if (match(Val, m_ExtractElt(m_Specific(Vec), m_Specific(Idx)))) 4501 return Vec; 4502 4503 return nullptr; 4504 } 4505 4506 /// Given operands for an ExtractValueInst, see if we can fold the result. 4507 /// If not, this returns null. 4508 static Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 4509 const SimplifyQuery &, unsigned) { 4510 if (auto *CAgg = dyn_cast<Constant>(Agg)) 4511 return ConstantFoldExtractValueInstruction(CAgg, Idxs); 4512 4513 // extractvalue x, (insertvalue y, elt, n), n -> elt 4514 unsigned NumIdxs = Idxs.size(); 4515 for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr; 4516 IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) { 4517 ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices(); 4518 unsigned NumInsertValueIdxs = InsertValueIdxs.size(); 4519 unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs); 4520 if (InsertValueIdxs.slice(0, NumCommonIdxs) == 4521 Idxs.slice(0, NumCommonIdxs)) { 4522 if (NumIdxs == NumInsertValueIdxs) 4523 return IVI->getInsertedValueOperand(); 4524 break; 4525 } 4526 } 4527 4528 return nullptr; 4529 } 4530 4531 Value *llvm::SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 4532 const SimplifyQuery &Q) { 4533 return ::SimplifyExtractValueInst(Agg, Idxs, Q, RecursionLimit); 4534 } 4535 4536 /// Given operands for an ExtractElementInst, see if we can fold the result. 4537 /// If not, this returns null. 4538 static Value *SimplifyExtractElementInst(Value *Vec, Value *Idx, 4539 const SimplifyQuery &Q, unsigned) { 4540 auto *VecVTy = cast<VectorType>(Vec->getType()); 4541 if (auto *CVec = dyn_cast<Constant>(Vec)) { 4542 if (auto *CIdx = dyn_cast<Constant>(Idx)) 4543 return ConstantExpr::getExtractElement(CVec, CIdx); 4544 4545 // The index is not relevant if our vector is a splat. 4546 if (auto *Splat = CVec->getSplatValue()) 4547 return Splat; 4548 4549 if (Q.isUndefValue(Vec)) 4550 return UndefValue::get(VecVTy->getElementType()); 4551 } 4552 4553 // If extracting a specified index from the vector, see if we can recursively 4554 // find a previously computed scalar that was inserted into the vector. 4555 if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) { 4556 // For fixed-length vector, fold into undef if index is out of bounds. 4557 if (isa<FixedVectorType>(VecVTy) && 4558 IdxC->getValue().uge(cast<FixedVectorType>(VecVTy)->getNumElements())) 4559 return PoisonValue::get(VecVTy->getElementType()); 4560 if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue())) 4561 return Elt; 4562 } 4563 4564 // An undef extract index can be arbitrarily chosen to be an out-of-range 4565 // index value, which would result in the instruction being poison. 4566 if (Q.isUndefValue(Idx)) 4567 return PoisonValue::get(VecVTy->getElementType()); 4568 4569 return nullptr; 4570 } 4571 4572 Value *llvm::SimplifyExtractElementInst(Value *Vec, Value *Idx, 4573 const SimplifyQuery &Q) { 4574 return ::SimplifyExtractElementInst(Vec, Idx, Q, RecursionLimit); 4575 } 4576 4577 /// See if we can fold the given phi. If not, returns null. 4578 static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) { 4579 // WARNING: no matter how worthwhile it may seem, we can not perform PHI CSE 4580 // here, because the PHI we may succeed simplifying to was not 4581 // def-reachable from the original PHI! 4582 4583 // If all of the PHI's incoming values are the same then replace the PHI node 4584 // with the common value. 4585 Value *CommonValue = nullptr; 4586 bool HasUndefInput = false; 4587 for (Value *Incoming : PN->incoming_values()) { 4588 // If the incoming value is the phi node itself, it can safely be skipped. 4589 if (Incoming == PN) continue; 4590 if (Q.isUndefValue(Incoming)) { 4591 // Remember that we saw an undef value, but otherwise ignore them. 4592 HasUndefInput = true; 4593 continue; 4594 } 4595 if (CommonValue && Incoming != CommonValue) 4596 return nullptr; // Not the same, bail out. 4597 CommonValue = Incoming; 4598 } 4599 4600 // If CommonValue is null then all of the incoming values were either undef or 4601 // equal to the phi node itself. 4602 if (!CommonValue) 4603 return UndefValue::get(PN->getType()); 4604 4605 // If we have a PHI node like phi(X, undef, X), where X is defined by some 4606 // instruction, we cannot return X as the result of the PHI node unless it 4607 // dominates the PHI block. 4608 if (HasUndefInput) 4609 return valueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr; 4610 4611 return CommonValue; 4612 } 4613 4614 static Value *SimplifyCastInst(unsigned CastOpc, Value *Op, 4615 Type *Ty, const SimplifyQuery &Q, unsigned MaxRecurse) { 4616 if (auto *C = dyn_cast<Constant>(Op)) 4617 return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL); 4618 4619 if (auto *CI = dyn_cast<CastInst>(Op)) { 4620 auto *Src = CI->getOperand(0); 4621 Type *SrcTy = Src->getType(); 4622 Type *MidTy = CI->getType(); 4623 Type *DstTy = Ty; 4624 if (Src->getType() == Ty) { 4625 auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode()); 4626 auto SecondOp = static_cast<Instruction::CastOps>(CastOpc); 4627 Type *SrcIntPtrTy = 4628 SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr; 4629 Type *MidIntPtrTy = 4630 MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr; 4631 Type *DstIntPtrTy = 4632 DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr; 4633 if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy, 4634 SrcIntPtrTy, MidIntPtrTy, 4635 DstIntPtrTy) == Instruction::BitCast) 4636 return Src; 4637 } 4638 } 4639 4640 // bitcast x -> x 4641 if (CastOpc == Instruction::BitCast) 4642 if (Op->getType() == Ty) 4643 return Op; 4644 4645 return nullptr; 4646 } 4647 4648 Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 4649 const SimplifyQuery &Q) { 4650 return ::SimplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit); 4651 } 4652 4653 /// For the given destination element of a shuffle, peek through shuffles to 4654 /// match a root vector source operand that contains that element in the same 4655 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s). 4656 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1, 4657 int MaskVal, Value *RootVec, 4658 unsigned MaxRecurse) { 4659 if (!MaxRecurse--) 4660 return nullptr; 4661 4662 // Bail out if any mask value is undefined. That kind of shuffle may be 4663 // simplified further based on demanded bits or other folds. 4664 if (MaskVal == -1) 4665 return nullptr; 4666 4667 // The mask value chooses which source operand we need to look at next. 4668 int InVecNumElts = cast<FixedVectorType>(Op0->getType())->getNumElements(); 4669 int RootElt = MaskVal; 4670 Value *SourceOp = Op0; 4671 if (MaskVal >= InVecNumElts) { 4672 RootElt = MaskVal - InVecNumElts; 4673 SourceOp = Op1; 4674 } 4675 4676 // If the source operand is a shuffle itself, look through it to find the 4677 // matching root vector. 4678 if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) { 4679 return foldIdentityShuffles( 4680 DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1), 4681 SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse); 4682 } 4683 4684 // TODO: Look through bitcasts? What if the bitcast changes the vector element 4685 // size? 4686 4687 // The source operand is not a shuffle. Initialize the root vector value for 4688 // this shuffle if that has not been done yet. 4689 if (!RootVec) 4690 RootVec = SourceOp; 4691 4692 // Give up as soon as a source operand does not match the existing root value. 4693 if (RootVec != SourceOp) 4694 return nullptr; 4695 4696 // The element must be coming from the same lane in the source vector 4697 // (although it may have crossed lanes in intermediate shuffles). 4698 if (RootElt != DestElt) 4699 return nullptr; 4700 4701 return RootVec; 4702 } 4703 4704 static Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, 4705 ArrayRef<int> Mask, Type *RetTy, 4706 const SimplifyQuery &Q, 4707 unsigned MaxRecurse) { 4708 if (all_of(Mask, [](int Elem) { return Elem == UndefMaskElem; })) 4709 return UndefValue::get(RetTy); 4710 4711 auto *InVecTy = cast<VectorType>(Op0->getType()); 4712 unsigned MaskNumElts = Mask.size(); 4713 ElementCount InVecEltCount = InVecTy->getElementCount(); 4714 4715 bool Scalable = InVecEltCount.isScalable(); 4716 4717 SmallVector<int, 32> Indices; 4718 Indices.assign(Mask.begin(), Mask.end()); 4719 4720 // Canonicalization: If mask does not select elements from an input vector, 4721 // replace that input vector with poison. 4722 if (!Scalable) { 4723 bool MaskSelects0 = false, MaskSelects1 = false; 4724 unsigned InVecNumElts = InVecEltCount.getKnownMinValue(); 4725 for (unsigned i = 0; i != MaskNumElts; ++i) { 4726 if (Indices[i] == -1) 4727 continue; 4728 if ((unsigned)Indices[i] < InVecNumElts) 4729 MaskSelects0 = true; 4730 else 4731 MaskSelects1 = true; 4732 } 4733 if (!MaskSelects0) 4734 Op0 = PoisonValue::get(InVecTy); 4735 if (!MaskSelects1) 4736 Op1 = PoisonValue::get(InVecTy); 4737 } 4738 4739 auto *Op0Const = dyn_cast<Constant>(Op0); 4740 auto *Op1Const = dyn_cast<Constant>(Op1); 4741 4742 // If all operands are constant, constant fold the shuffle. This 4743 // transformation depends on the value of the mask which is not known at 4744 // compile time for scalable vectors 4745 if (Op0Const && Op1Const) 4746 return ConstantExpr::getShuffleVector(Op0Const, Op1Const, Mask); 4747 4748 // Canonicalization: if only one input vector is constant, it shall be the 4749 // second one. This transformation depends on the value of the mask which 4750 // is not known at compile time for scalable vectors 4751 if (!Scalable && Op0Const && !Op1Const) { 4752 std::swap(Op0, Op1); 4753 ShuffleVectorInst::commuteShuffleMask(Indices, 4754 InVecEltCount.getKnownMinValue()); 4755 } 4756 4757 // A splat of an inserted scalar constant becomes a vector constant: 4758 // shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...> 4759 // NOTE: We may have commuted above, so analyze the updated Indices, not the 4760 // original mask constant. 4761 // NOTE: This transformation depends on the value of the mask which is not 4762 // known at compile time for scalable vectors 4763 Constant *C; 4764 ConstantInt *IndexC; 4765 if (!Scalable && match(Op0, m_InsertElt(m_Value(), m_Constant(C), 4766 m_ConstantInt(IndexC)))) { 4767 // Match a splat shuffle mask of the insert index allowing undef elements. 4768 int InsertIndex = IndexC->getZExtValue(); 4769 if (all_of(Indices, [InsertIndex](int MaskElt) { 4770 return MaskElt == InsertIndex || MaskElt == -1; 4771 })) { 4772 assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat"); 4773 4774 // Shuffle mask undefs become undefined constant result elements. 4775 SmallVector<Constant *, 16> VecC(MaskNumElts, C); 4776 for (unsigned i = 0; i != MaskNumElts; ++i) 4777 if (Indices[i] == -1) 4778 VecC[i] = UndefValue::get(C->getType()); 4779 return ConstantVector::get(VecC); 4780 } 4781 } 4782 4783 // A shuffle of a splat is always the splat itself. Legal if the shuffle's 4784 // value type is same as the input vectors' type. 4785 if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0)) 4786 if (Q.isUndefValue(Op1) && RetTy == InVecTy && 4787 is_splat(OpShuf->getShuffleMask())) 4788 return Op0; 4789 4790 // All remaining transformation depend on the value of the mask, which is 4791 // not known at compile time for scalable vectors. 4792 if (Scalable) 4793 return nullptr; 4794 4795 // Don't fold a shuffle with undef mask elements. This may get folded in a 4796 // better way using demanded bits or other analysis. 4797 // TODO: Should we allow this? 4798 if (is_contained(Indices, -1)) 4799 return nullptr; 4800 4801 // Check if every element of this shuffle can be mapped back to the 4802 // corresponding element of a single root vector. If so, we don't need this 4803 // shuffle. This handles simple identity shuffles as well as chains of 4804 // shuffles that may widen/narrow and/or move elements across lanes and back. 4805 Value *RootVec = nullptr; 4806 for (unsigned i = 0; i != MaskNumElts; ++i) { 4807 // Note that recursion is limited for each vector element, so if any element 4808 // exceeds the limit, this will fail to simplify. 4809 RootVec = 4810 foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse); 4811 4812 // We can't replace a widening/narrowing shuffle with one of its operands. 4813 if (!RootVec || RootVec->getType() != RetTy) 4814 return nullptr; 4815 } 4816 return RootVec; 4817 } 4818 4819 /// Given operands for a ShuffleVectorInst, fold the result or return null. 4820 Value *llvm::SimplifyShuffleVectorInst(Value *Op0, Value *Op1, 4821 ArrayRef<int> Mask, Type *RetTy, 4822 const SimplifyQuery &Q) { 4823 return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit); 4824 } 4825 4826 static Constant *foldConstant(Instruction::UnaryOps Opcode, 4827 Value *&Op, const SimplifyQuery &Q) { 4828 if (auto *C = dyn_cast<Constant>(Op)) 4829 return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL); 4830 return nullptr; 4831 } 4832 4833 /// Given the operand for an FNeg, see if we can fold the result. If not, this 4834 /// returns null. 4835 static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, 4836 const SimplifyQuery &Q, unsigned MaxRecurse) { 4837 if (Constant *C = foldConstant(Instruction::FNeg, Op, Q)) 4838 return C; 4839 4840 Value *X; 4841 // fneg (fneg X) ==> X 4842 if (match(Op, m_FNeg(m_Value(X)))) 4843 return X; 4844 4845 return nullptr; 4846 } 4847 4848 Value *llvm::SimplifyFNegInst(Value *Op, FastMathFlags FMF, 4849 const SimplifyQuery &Q) { 4850 return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit); 4851 } 4852 4853 static Constant *propagateNaN(Constant *In) { 4854 // If the input is a vector with undef elements, just return a default NaN. 4855 if (!In->isNaN()) 4856 return ConstantFP::getNaN(In->getType()); 4857 4858 // Propagate the existing NaN constant when possible. 4859 // TODO: Should we quiet a signaling NaN? 4860 return In; 4861 } 4862 4863 /// Perform folds that are common to any floating-point operation. This implies 4864 /// transforms based on undef/NaN because the operation itself makes no 4865 /// difference to the result. 4866 static Constant *simplifyFPOp(ArrayRef<Value *> Ops, 4867 FastMathFlags FMF, 4868 const SimplifyQuery &Q) { 4869 for (Value *V : Ops) { 4870 bool IsNan = match(V, m_NaN()); 4871 bool IsInf = match(V, m_Inf()); 4872 bool IsUndef = Q.isUndefValue(V); 4873 4874 // If this operation has 'nnan' or 'ninf' and at least 1 disallowed operand 4875 // (an undef operand can be chosen to be Nan/Inf), then the result of 4876 // this operation is poison. 4877 if (FMF.noNaNs() && (IsNan || IsUndef)) 4878 return PoisonValue::get(V->getType()); 4879 if (FMF.noInfs() && (IsInf || IsUndef)) 4880 return PoisonValue::get(V->getType()); 4881 4882 if (IsUndef || IsNan) 4883 return propagateNaN(cast<Constant>(V)); 4884 } 4885 return nullptr; 4886 } 4887 4888 /// Given operands for an FAdd, see if we can fold the result. If not, this 4889 /// returns null. 4890 static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4891 const SimplifyQuery &Q, unsigned MaxRecurse) { 4892 if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q)) 4893 return C; 4894 4895 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 4896 return C; 4897 4898 // fadd X, -0 ==> X 4899 if (match(Op1, m_NegZeroFP())) 4900 return Op0; 4901 4902 // fadd X, 0 ==> X, when we know X is not -0 4903 if (match(Op1, m_PosZeroFP()) && 4904 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI))) 4905 return Op0; 4906 4907 // With nnan: -X + X --> 0.0 (and commuted variant) 4908 // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN. 4909 // Negative zeros are allowed because we always end up with positive zero: 4910 // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 4911 // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 4912 // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0 4913 // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0 4914 if (FMF.noNaNs()) { 4915 if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || 4916 match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))) 4917 return ConstantFP::getNullValue(Op0->getType()); 4918 4919 if (match(Op0, m_FNeg(m_Specific(Op1))) || 4920 match(Op1, m_FNeg(m_Specific(Op0)))) 4921 return ConstantFP::getNullValue(Op0->getType()); 4922 } 4923 4924 // (X - Y) + Y --> X 4925 // Y + (X - Y) --> X 4926 Value *X; 4927 if (FMF.noSignedZeros() && FMF.allowReassoc() && 4928 (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) || 4929 match(Op1, m_FSub(m_Value(X), m_Specific(Op0))))) 4930 return X; 4931 4932 return nullptr; 4933 } 4934 4935 /// Given operands for an FSub, see if we can fold the result. If not, this 4936 /// returns null. 4937 static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 4938 const SimplifyQuery &Q, unsigned MaxRecurse) { 4939 if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q)) 4940 return C; 4941 4942 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 4943 return C; 4944 4945 // fsub X, +0 ==> X 4946 if (match(Op1, m_PosZeroFP())) 4947 return Op0; 4948 4949 // fsub X, -0 ==> X, when we know X is not -0 4950 if (match(Op1, m_NegZeroFP()) && 4951 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI))) 4952 return Op0; 4953 4954 // fsub -0.0, (fsub -0.0, X) ==> X 4955 // fsub -0.0, (fneg X) ==> X 4956 Value *X; 4957 if (match(Op0, m_NegZeroFP()) && 4958 match(Op1, m_FNeg(m_Value(X)))) 4959 return X; 4960 4961 // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored. 4962 // fsub 0.0, (fneg X) ==> X if signed zeros are ignored. 4963 if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) && 4964 (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) || 4965 match(Op1, m_FNeg(m_Value(X))))) 4966 return X; 4967 4968 // fsub nnan x, x ==> 0.0 4969 if (FMF.noNaNs() && Op0 == Op1) 4970 return Constant::getNullValue(Op0->getType()); 4971 4972 // Y - (Y - X) --> X 4973 // (X + Y) - Y --> X 4974 if (FMF.noSignedZeros() && FMF.allowReassoc() && 4975 (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) || 4976 match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X))))) 4977 return X; 4978 4979 return nullptr; 4980 } 4981 4982 static Value *SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 4983 const SimplifyQuery &Q, unsigned MaxRecurse) { 4984 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 4985 return C; 4986 4987 // fmul X, 1.0 ==> X 4988 if (match(Op1, m_FPOne())) 4989 return Op0; 4990 4991 // fmul 1.0, X ==> X 4992 if (match(Op0, m_FPOne())) 4993 return Op1; 4994 4995 // fmul nnan nsz X, 0 ==> 0 4996 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZeroFP())) 4997 return ConstantFP::getNullValue(Op0->getType()); 4998 4999 // fmul nnan nsz 0, X ==> 0 5000 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) 5001 return ConstantFP::getNullValue(Op1->getType()); 5002 5003 // sqrt(X) * sqrt(X) --> X, if we can: 5004 // 1. Remove the intermediate rounding (reassociate). 5005 // 2. Ignore non-zero negative numbers because sqrt would produce NAN. 5006 // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0. 5007 Value *X; 5008 if (Op0 == Op1 && match(Op0, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) && 5009 FMF.allowReassoc() && FMF.noNaNs() && FMF.noSignedZeros()) 5010 return X; 5011 5012 return nullptr; 5013 } 5014 5015 /// Given the operands for an FMul, see if we can fold the result 5016 static Value *SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5017 const SimplifyQuery &Q, unsigned MaxRecurse) { 5018 if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q)) 5019 return C; 5020 5021 // Now apply simplifications that do not require rounding. 5022 return SimplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse); 5023 } 5024 5025 Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5026 const SimplifyQuery &Q) { 5027 return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit); 5028 } 5029 5030 5031 Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5032 const SimplifyQuery &Q) { 5033 return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit); 5034 } 5035 5036 Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5037 const SimplifyQuery &Q) { 5038 return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit); 5039 } 5040 5041 Value *llvm::SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 5042 const SimplifyQuery &Q) { 5043 return ::SimplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit); 5044 } 5045 5046 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5047 const SimplifyQuery &Q, unsigned) { 5048 if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q)) 5049 return C; 5050 5051 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 5052 return C; 5053 5054 // X / 1.0 -> X 5055 if (match(Op1, m_FPOne())) 5056 return Op0; 5057 5058 // 0 / X -> 0 5059 // Requires that NaNs are off (X could be zero) and signed zeroes are 5060 // ignored (X could be positive or negative, so the output sign is unknown). 5061 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) 5062 return ConstantFP::getNullValue(Op0->getType()); 5063 5064 if (FMF.noNaNs()) { 5065 // X / X -> 1.0 is legal when NaNs are ignored. 5066 // We can ignore infinities because INF/INF is NaN. 5067 if (Op0 == Op1) 5068 return ConstantFP::get(Op0->getType(), 1.0); 5069 5070 // (X * Y) / Y --> X if we can reassociate to the above form. 5071 Value *X; 5072 if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1)))) 5073 return X; 5074 5075 // -X / X -> -1.0 and 5076 // X / -X -> -1.0 are legal when NaNs are ignored. 5077 // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored. 5078 if (match(Op0, m_FNegNSZ(m_Specific(Op1))) || 5079 match(Op1, m_FNegNSZ(m_Specific(Op0)))) 5080 return ConstantFP::get(Op0->getType(), -1.0); 5081 } 5082 5083 return nullptr; 5084 } 5085 5086 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5087 const SimplifyQuery &Q) { 5088 return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit); 5089 } 5090 5091 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5092 const SimplifyQuery &Q, unsigned) { 5093 if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q)) 5094 return C; 5095 5096 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q)) 5097 return C; 5098 5099 // Unlike fdiv, the result of frem always matches the sign of the dividend. 5100 // The constant match may include undef elements in a vector, so return a full 5101 // zero constant as the result. 5102 if (FMF.noNaNs()) { 5103 // +0 % X -> 0 5104 if (match(Op0, m_PosZeroFP())) 5105 return ConstantFP::getNullValue(Op0->getType()); 5106 // -0 % X -> -0 5107 if (match(Op0, m_NegZeroFP())) 5108 return ConstantFP::getNegativeZero(Op0->getType()); 5109 } 5110 5111 return nullptr; 5112 } 5113 5114 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5115 const SimplifyQuery &Q) { 5116 return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit); 5117 } 5118 5119 //=== Helper functions for higher up the class hierarchy. 5120 5121 /// Given the operand for a UnaryOperator, see if we can fold the result. 5122 /// If not, this returns null. 5123 static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q, 5124 unsigned MaxRecurse) { 5125 switch (Opcode) { 5126 case Instruction::FNeg: 5127 return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse); 5128 default: 5129 llvm_unreachable("Unexpected opcode"); 5130 } 5131 } 5132 5133 /// Given the operand for a UnaryOperator, see if we can fold the result. 5134 /// If not, this returns null. 5135 /// Try to use FastMathFlags when folding the result. 5136 static Value *simplifyFPUnOp(unsigned Opcode, Value *Op, 5137 const FastMathFlags &FMF, 5138 const SimplifyQuery &Q, unsigned MaxRecurse) { 5139 switch (Opcode) { 5140 case Instruction::FNeg: 5141 return simplifyFNegInst(Op, FMF, Q, MaxRecurse); 5142 default: 5143 return simplifyUnOp(Opcode, Op, Q, MaxRecurse); 5144 } 5145 } 5146 5147 Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) { 5148 return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit); 5149 } 5150 5151 Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 5152 const SimplifyQuery &Q) { 5153 return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit); 5154 } 5155 5156 /// Given operands for a BinaryOperator, see if we can fold the result. 5157 /// If not, this returns null. 5158 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5159 const SimplifyQuery &Q, unsigned MaxRecurse) { 5160 switch (Opcode) { 5161 case Instruction::Add: 5162 return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse); 5163 case Instruction::Sub: 5164 return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse); 5165 case Instruction::Mul: 5166 return SimplifyMulInst(LHS, RHS, Q, MaxRecurse); 5167 case Instruction::SDiv: 5168 return SimplifySDivInst(LHS, RHS, Q, MaxRecurse); 5169 case Instruction::UDiv: 5170 return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse); 5171 case Instruction::SRem: 5172 return SimplifySRemInst(LHS, RHS, Q, MaxRecurse); 5173 case Instruction::URem: 5174 return SimplifyURemInst(LHS, RHS, Q, MaxRecurse); 5175 case Instruction::Shl: 5176 return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse); 5177 case Instruction::LShr: 5178 return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse); 5179 case Instruction::AShr: 5180 return SimplifyAShrInst(LHS, RHS, false, Q, MaxRecurse); 5181 case Instruction::And: 5182 return SimplifyAndInst(LHS, RHS, Q, MaxRecurse); 5183 case Instruction::Or: 5184 return SimplifyOrInst(LHS, RHS, Q, MaxRecurse); 5185 case Instruction::Xor: 5186 return SimplifyXorInst(LHS, RHS, Q, MaxRecurse); 5187 case Instruction::FAdd: 5188 return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5189 case Instruction::FSub: 5190 return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5191 case Instruction::FMul: 5192 return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5193 case Instruction::FDiv: 5194 return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5195 case Instruction::FRem: 5196 return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5197 default: 5198 llvm_unreachable("Unexpected opcode"); 5199 } 5200 } 5201 5202 /// Given operands for a BinaryOperator, see if we can fold the result. 5203 /// If not, this returns null. 5204 /// Try to use FastMathFlags when folding the result. 5205 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5206 const FastMathFlags &FMF, const SimplifyQuery &Q, 5207 unsigned MaxRecurse) { 5208 switch (Opcode) { 5209 case Instruction::FAdd: 5210 return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse); 5211 case Instruction::FSub: 5212 return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse); 5213 case Instruction::FMul: 5214 return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse); 5215 case Instruction::FDiv: 5216 return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse); 5217 default: 5218 return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse); 5219 } 5220 } 5221 5222 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5223 const SimplifyQuery &Q) { 5224 return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit); 5225 } 5226 5227 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5228 FastMathFlags FMF, const SimplifyQuery &Q) { 5229 return ::SimplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit); 5230 } 5231 5232 /// Given operands for a CmpInst, see if we can fold the result. 5233 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 5234 const SimplifyQuery &Q, unsigned MaxRecurse) { 5235 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 5236 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 5237 return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse); 5238 } 5239 5240 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 5241 const SimplifyQuery &Q) { 5242 return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 5243 } 5244 5245 static bool IsIdempotent(Intrinsic::ID ID) { 5246 switch (ID) { 5247 default: return false; 5248 5249 // Unary idempotent: f(f(x)) = f(x) 5250 case Intrinsic::fabs: 5251 case Intrinsic::floor: 5252 case Intrinsic::ceil: 5253 case Intrinsic::trunc: 5254 case Intrinsic::rint: 5255 case Intrinsic::nearbyint: 5256 case Intrinsic::round: 5257 case Intrinsic::roundeven: 5258 case Intrinsic::canonicalize: 5259 return true; 5260 } 5261 } 5262 5263 static Value *SimplifyRelativeLoad(Constant *Ptr, Constant *Offset, 5264 const DataLayout &DL) { 5265 GlobalValue *PtrSym; 5266 APInt PtrOffset; 5267 if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL)) 5268 return nullptr; 5269 5270 Type *Int8PtrTy = Type::getInt8PtrTy(Ptr->getContext()); 5271 Type *Int32Ty = Type::getInt32Ty(Ptr->getContext()); 5272 Type *Int32PtrTy = Int32Ty->getPointerTo(); 5273 Type *Int64Ty = Type::getInt64Ty(Ptr->getContext()); 5274 5275 auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset); 5276 if (!OffsetConstInt || OffsetConstInt->getType()->getBitWidth() > 64) 5277 return nullptr; 5278 5279 uint64_t OffsetInt = OffsetConstInt->getSExtValue(); 5280 if (OffsetInt % 4 != 0) 5281 return nullptr; 5282 5283 Constant *C = ConstantExpr::getGetElementPtr( 5284 Int32Ty, ConstantExpr::getBitCast(Ptr, Int32PtrTy), 5285 ConstantInt::get(Int64Ty, OffsetInt / 4)); 5286 Constant *Loaded = ConstantFoldLoadFromConstPtr(C, Int32Ty, DL); 5287 if (!Loaded) 5288 return nullptr; 5289 5290 auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded); 5291 if (!LoadedCE) 5292 return nullptr; 5293 5294 if (LoadedCE->getOpcode() == Instruction::Trunc) { 5295 LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 5296 if (!LoadedCE) 5297 return nullptr; 5298 } 5299 5300 if (LoadedCE->getOpcode() != Instruction::Sub) 5301 return nullptr; 5302 5303 auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 5304 if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt) 5305 return nullptr; 5306 auto *LoadedLHSPtr = LoadedLHS->getOperand(0); 5307 5308 Constant *LoadedRHS = LoadedCE->getOperand(1); 5309 GlobalValue *LoadedRHSSym; 5310 APInt LoadedRHSOffset; 5311 if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset, 5312 DL) || 5313 PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset) 5314 return nullptr; 5315 5316 return ConstantExpr::getBitCast(LoadedLHSPtr, Int8PtrTy); 5317 } 5318 5319 static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0, 5320 const SimplifyQuery &Q) { 5321 // Idempotent functions return the same result when called repeatedly. 5322 Intrinsic::ID IID = F->getIntrinsicID(); 5323 if (IsIdempotent(IID)) 5324 if (auto *II = dyn_cast<IntrinsicInst>(Op0)) 5325 if (II->getIntrinsicID() == IID) 5326 return II; 5327 5328 Value *X; 5329 switch (IID) { 5330 case Intrinsic::fabs: 5331 if (SignBitMustBeZero(Op0, Q.TLI)) return Op0; 5332 break; 5333 case Intrinsic::bswap: 5334 // bswap(bswap(x)) -> x 5335 if (match(Op0, m_BSwap(m_Value(X)))) return X; 5336 break; 5337 case Intrinsic::bitreverse: 5338 // bitreverse(bitreverse(x)) -> x 5339 if (match(Op0, m_BitReverse(m_Value(X)))) return X; 5340 break; 5341 case Intrinsic::ctpop: { 5342 // If everything but the lowest bit is zero, that bit is the pop-count. Ex: 5343 // ctpop(and X, 1) --> and X, 1 5344 unsigned BitWidth = Op0->getType()->getScalarSizeInBits(); 5345 if (MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, BitWidth - 1), 5346 Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 5347 return Op0; 5348 break; 5349 } 5350 case Intrinsic::exp: 5351 // exp(log(x)) -> x 5352 if (Q.CxtI->hasAllowReassoc() && 5353 match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X)))) return X; 5354 break; 5355 case Intrinsic::exp2: 5356 // exp2(log2(x)) -> x 5357 if (Q.CxtI->hasAllowReassoc() && 5358 match(Op0, m_Intrinsic<Intrinsic::log2>(m_Value(X)))) return X; 5359 break; 5360 case Intrinsic::log: 5361 // log(exp(x)) -> x 5362 if (Q.CxtI->hasAllowReassoc() && 5363 match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X)))) return X; 5364 break; 5365 case Intrinsic::log2: 5366 // log2(exp2(x)) -> x 5367 if (Q.CxtI->hasAllowReassoc() && 5368 (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) || 5369 match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0), 5370 m_Value(X))))) return X; 5371 break; 5372 case Intrinsic::log10: 5373 // log10(pow(10.0, x)) -> x 5374 if (Q.CxtI->hasAllowReassoc() && 5375 match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), 5376 m_Value(X)))) return X; 5377 break; 5378 case Intrinsic::floor: 5379 case Intrinsic::trunc: 5380 case Intrinsic::ceil: 5381 case Intrinsic::round: 5382 case Intrinsic::roundeven: 5383 case Intrinsic::nearbyint: 5384 case Intrinsic::rint: { 5385 // floor (sitofp x) -> sitofp x 5386 // floor (uitofp x) -> uitofp x 5387 // 5388 // Converting from int always results in a finite integral number or 5389 // infinity. For either of those inputs, these rounding functions always 5390 // return the same value, so the rounding can be eliminated. 5391 if (match(Op0, m_SIToFP(m_Value())) || match(Op0, m_UIToFP(m_Value()))) 5392 return Op0; 5393 break; 5394 } 5395 case Intrinsic::experimental_vector_reverse: 5396 // experimental.vector.reverse(experimental.vector.reverse(x)) -> x 5397 if (match(Op0, 5398 m_Intrinsic<Intrinsic::experimental_vector_reverse>(m_Value(X)))) 5399 return X; 5400 break; 5401 default: 5402 break; 5403 } 5404 5405 return nullptr; 5406 } 5407 5408 static APInt getMaxMinLimit(Intrinsic::ID IID, unsigned BitWidth) { 5409 switch (IID) { 5410 case Intrinsic::smax: return APInt::getSignedMaxValue(BitWidth); 5411 case Intrinsic::smin: return APInt::getSignedMinValue(BitWidth); 5412 case Intrinsic::umax: return APInt::getMaxValue(BitWidth); 5413 case Intrinsic::umin: return APInt::getMinValue(BitWidth); 5414 default: llvm_unreachable("Unexpected intrinsic"); 5415 } 5416 } 5417 5418 static ICmpInst::Predicate getMaxMinPredicate(Intrinsic::ID IID) { 5419 switch (IID) { 5420 case Intrinsic::smax: return ICmpInst::ICMP_SGE; 5421 case Intrinsic::smin: return ICmpInst::ICMP_SLE; 5422 case Intrinsic::umax: return ICmpInst::ICMP_UGE; 5423 case Intrinsic::umin: return ICmpInst::ICMP_ULE; 5424 default: llvm_unreachable("Unexpected intrinsic"); 5425 } 5426 } 5427 5428 /// Given a min/max intrinsic, see if it can be removed based on having an 5429 /// operand that is another min/max intrinsic with shared operand(s). The caller 5430 /// is expected to swap the operand arguments to handle commutation. 5431 static Value *foldMinMaxSharedOp(Intrinsic::ID IID, Value *Op0, Value *Op1) { 5432 Value *X, *Y; 5433 if (!match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y)))) 5434 return nullptr; 5435 5436 auto *MM0 = dyn_cast<IntrinsicInst>(Op0); 5437 if (!MM0) 5438 return nullptr; 5439 Intrinsic::ID IID0 = MM0->getIntrinsicID(); 5440 5441 if (Op1 == X || Op1 == Y || 5442 match(Op1, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) { 5443 // max (max X, Y), X --> max X, Y 5444 if (IID0 == IID) 5445 return MM0; 5446 // max (min X, Y), X --> X 5447 if (IID0 == getInverseMinMaxIntrinsic(IID)) 5448 return Op1; 5449 } 5450 return nullptr; 5451 } 5452 5453 static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1, 5454 const SimplifyQuery &Q) { 5455 Intrinsic::ID IID = F->getIntrinsicID(); 5456 Type *ReturnType = F->getReturnType(); 5457 unsigned BitWidth = ReturnType->getScalarSizeInBits(); 5458 switch (IID) { 5459 case Intrinsic::abs: 5460 // abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here. 5461 // It is always ok to pick the earlier abs. We'll just lose nsw if its only 5462 // on the outer abs. 5463 if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(), m_Value()))) 5464 return Op0; 5465 break; 5466 5467 case Intrinsic::cttz: { 5468 Value *X; 5469 if (match(Op0, m_Shl(m_One(), m_Value(X)))) 5470 return X; 5471 break; 5472 } 5473 case Intrinsic::smax: 5474 case Intrinsic::smin: 5475 case Intrinsic::umax: 5476 case Intrinsic::umin: { 5477 // If the arguments are the same, this is a no-op. 5478 if (Op0 == Op1) 5479 return Op0; 5480 5481 // Canonicalize constant operand as Op1. 5482 if (isa<Constant>(Op0)) 5483 std::swap(Op0, Op1); 5484 5485 // Assume undef is the limit value. 5486 if (Q.isUndefValue(Op1)) 5487 return ConstantInt::get(ReturnType, getMaxMinLimit(IID, BitWidth)); 5488 5489 const APInt *C; 5490 if (match(Op1, m_APIntAllowUndef(C))) { 5491 // Clamp to limit value. For example: 5492 // umax(i8 %x, i8 255) --> 255 5493 if (*C == getMaxMinLimit(IID, BitWidth)) 5494 return ConstantInt::get(ReturnType, *C); 5495 5496 // If the constant op is the opposite of the limit value, the other must 5497 // be larger/smaller or equal. For example: 5498 // umin(i8 %x, i8 255) --> %x 5499 if (*C == getMaxMinLimit(getInverseMinMaxIntrinsic(IID), BitWidth)) 5500 return Op0; 5501 5502 // Remove nested call if constant operands allow it. Example: 5503 // max (max X, 7), 5 -> max X, 7 5504 auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0); 5505 if (MinMax0 && MinMax0->getIntrinsicID() == IID) { 5506 // TODO: loosen undef/splat restrictions for vector constants. 5507 Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1); 5508 const APInt *InnerC; 5509 if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) && 5510 ((IID == Intrinsic::smax && InnerC->sge(*C)) || 5511 (IID == Intrinsic::smin && InnerC->sle(*C)) || 5512 (IID == Intrinsic::umax && InnerC->uge(*C)) || 5513 (IID == Intrinsic::umin && InnerC->ule(*C)))) 5514 return Op0; 5515 } 5516 } 5517 5518 if (Value *V = foldMinMaxSharedOp(IID, Op0, Op1)) 5519 return V; 5520 if (Value *V = foldMinMaxSharedOp(IID, Op1, Op0)) 5521 return V; 5522 5523 ICmpInst::Predicate Pred = getMaxMinPredicate(IID); 5524 if (isICmpTrue(Pred, Op0, Op1, Q.getWithoutUndef(), RecursionLimit)) 5525 return Op0; 5526 if (isICmpTrue(Pred, Op1, Op0, Q.getWithoutUndef(), RecursionLimit)) 5527 return Op1; 5528 5529 if (Optional<bool> Imp = 5530 isImpliedByDomCondition(Pred, Op0, Op1, Q.CxtI, Q.DL)) 5531 return *Imp ? Op0 : Op1; 5532 if (Optional<bool> Imp = 5533 isImpliedByDomCondition(Pred, Op1, Op0, Q.CxtI, Q.DL)) 5534 return *Imp ? Op1 : Op0; 5535 5536 break; 5537 } 5538 case Intrinsic::usub_with_overflow: 5539 case Intrinsic::ssub_with_overflow: 5540 // X - X -> { 0, false } 5541 // X - undef -> { 0, false } 5542 // undef - X -> { 0, false } 5543 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5544 return Constant::getNullValue(ReturnType); 5545 break; 5546 case Intrinsic::uadd_with_overflow: 5547 case Intrinsic::sadd_with_overflow: 5548 // X + undef -> { -1, false } 5549 // undef + x -> { -1, false } 5550 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) { 5551 return ConstantStruct::get( 5552 cast<StructType>(ReturnType), 5553 {Constant::getAllOnesValue(ReturnType->getStructElementType(0)), 5554 Constant::getNullValue(ReturnType->getStructElementType(1))}); 5555 } 5556 break; 5557 case Intrinsic::umul_with_overflow: 5558 case Intrinsic::smul_with_overflow: 5559 // 0 * X -> { 0, false } 5560 // X * 0 -> { 0, false } 5561 if (match(Op0, m_Zero()) || match(Op1, m_Zero())) 5562 return Constant::getNullValue(ReturnType); 5563 // undef * X -> { 0, false } 5564 // X * undef -> { 0, false } 5565 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5566 return Constant::getNullValue(ReturnType); 5567 break; 5568 case Intrinsic::uadd_sat: 5569 // sat(MAX + X) -> MAX 5570 // sat(X + MAX) -> MAX 5571 if (match(Op0, m_AllOnes()) || match(Op1, m_AllOnes())) 5572 return Constant::getAllOnesValue(ReturnType); 5573 LLVM_FALLTHROUGH; 5574 case Intrinsic::sadd_sat: 5575 // sat(X + undef) -> -1 5576 // sat(undef + X) -> -1 5577 // For unsigned: Assume undef is MAX, thus we saturate to MAX (-1). 5578 // For signed: Assume undef is ~X, in which case X + ~X = -1. 5579 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5580 return Constant::getAllOnesValue(ReturnType); 5581 5582 // X + 0 -> X 5583 if (match(Op1, m_Zero())) 5584 return Op0; 5585 // 0 + X -> X 5586 if (match(Op0, m_Zero())) 5587 return Op1; 5588 break; 5589 case Intrinsic::usub_sat: 5590 // sat(0 - X) -> 0, sat(X - MAX) -> 0 5591 if (match(Op0, m_Zero()) || match(Op1, m_AllOnes())) 5592 return Constant::getNullValue(ReturnType); 5593 LLVM_FALLTHROUGH; 5594 case Intrinsic::ssub_sat: 5595 // X - X -> 0, X - undef -> 0, undef - X -> 0 5596 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 5597 return Constant::getNullValue(ReturnType); 5598 // X - 0 -> X 5599 if (match(Op1, m_Zero())) 5600 return Op0; 5601 break; 5602 case Intrinsic::load_relative: 5603 if (auto *C0 = dyn_cast<Constant>(Op0)) 5604 if (auto *C1 = dyn_cast<Constant>(Op1)) 5605 return SimplifyRelativeLoad(C0, C1, Q.DL); 5606 break; 5607 case Intrinsic::powi: 5608 if (auto *Power = dyn_cast<ConstantInt>(Op1)) { 5609 // powi(x, 0) -> 1.0 5610 if (Power->isZero()) 5611 return ConstantFP::get(Op0->getType(), 1.0); 5612 // powi(x, 1) -> x 5613 if (Power->isOne()) 5614 return Op0; 5615 } 5616 break; 5617 case Intrinsic::copysign: 5618 // copysign X, X --> X 5619 if (Op0 == Op1) 5620 return Op0; 5621 // copysign -X, X --> X 5622 // copysign X, -X --> -X 5623 if (match(Op0, m_FNeg(m_Specific(Op1))) || 5624 match(Op1, m_FNeg(m_Specific(Op0)))) 5625 return Op1; 5626 break; 5627 case Intrinsic::maxnum: 5628 case Intrinsic::minnum: 5629 case Intrinsic::maximum: 5630 case Intrinsic::minimum: { 5631 // If the arguments are the same, this is a no-op. 5632 if (Op0 == Op1) return Op0; 5633 5634 // Canonicalize constant operand as Op1. 5635 if (isa<Constant>(Op0)) 5636 std::swap(Op0, Op1); 5637 5638 // If an argument is undef, return the other argument. 5639 if (Q.isUndefValue(Op1)) 5640 return Op0; 5641 5642 bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum; 5643 bool IsMin = IID == Intrinsic::minimum || IID == Intrinsic::minnum; 5644 5645 // minnum(X, nan) -> X 5646 // maxnum(X, nan) -> X 5647 // minimum(X, nan) -> nan 5648 // maximum(X, nan) -> nan 5649 if (match(Op1, m_NaN())) 5650 return PropagateNaN ? propagateNaN(cast<Constant>(Op1)) : Op0; 5651 5652 // In the following folds, inf can be replaced with the largest finite 5653 // float, if the ninf flag is set. 5654 const APFloat *C; 5655 if (match(Op1, m_APFloat(C)) && 5656 (C->isInfinity() || (Q.CxtI->hasNoInfs() && C->isLargest()))) { 5657 // minnum(X, -inf) -> -inf 5658 // maxnum(X, +inf) -> +inf 5659 // minimum(X, -inf) -> -inf if nnan 5660 // maximum(X, +inf) -> +inf if nnan 5661 if (C->isNegative() == IsMin && (!PropagateNaN || Q.CxtI->hasNoNaNs())) 5662 return ConstantFP::get(ReturnType, *C); 5663 5664 // minnum(X, +inf) -> X if nnan 5665 // maxnum(X, -inf) -> X if nnan 5666 // minimum(X, +inf) -> X 5667 // maximum(X, -inf) -> X 5668 if (C->isNegative() != IsMin && (PropagateNaN || Q.CxtI->hasNoNaNs())) 5669 return Op0; 5670 } 5671 5672 // Min/max of the same operation with common operand: 5673 // m(m(X, Y)), X --> m(X, Y) (4 commuted variants) 5674 if (auto *M0 = dyn_cast<IntrinsicInst>(Op0)) 5675 if (M0->getIntrinsicID() == IID && 5676 (M0->getOperand(0) == Op1 || M0->getOperand(1) == Op1)) 5677 return Op0; 5678 if (auto *M1 = dyn_cast<IntrinsicInst>(Op1)) 5679 if (M1->getIntrinsicID() == IID && 5680 (M1->getOperand(0) == Op0 || M1->getOperand(1) == Op0)) 5681 return Op1; 5682 5683 break; 5684 } 5685 default: 5686 break; 5687 } 5688 5689 return nullptr; 5690 } 5691 5692 static Value *simplifyIntrinsic(CallBase *Call, const SimplifyQuery &Q) { 5693 5694 // Intrinsics with no operands have some kind of side effect. Don't simplify. 5695 unsigned NumOperands = Call->getNumArgOperands(); 5696 if (!NumOperands) 5697 return nullptr; 5698 5699 Function *F = cast<Function>(Call->getCalledFunction()); 5700 Intrinsic::ID IID = F->getIntrinsicID(); 5701 if (NumOperands == 1) 5702 return simplifyUnaryIntrinsic(F, Call->getArgOperand(0), Q); 5703 5704 if (NumOperands == 2) 5705 return simplifyBinaryIntrinsic(F, Call->getArgOperand(0), 5706 Call->getArgOperand(1), Q); 5707 5708 // Handle intrinsics with 3 or more arguments. 5709 switch (IID) { 5710 case Intrinsic::masked_load: 5711 case Intrinsic::masked_gather: { 5712 Value *MaskArg = Call->getArgOperand(2); 5713 Value *PassthruArg = Call->getArgOperand(3); 5714 // If the mask is all zeros or undef, the "passthru" argument is the result. 5715 if (maskIsAllZeroOrUndef(MaskArg)) 5716 return PassthruArg; 5717 return nullptr; 5718 } 5719 case Intrinsic::fshl: 5720 case Intrinsic::fshr: { 5721 Value *Op0 = Call->getArgOperand(0), *Op1 = Call->getArgOperand(1), 5722 *ShAmtArg = Call->getArgOperand(2); 5723 5724 // If both operands are undef, the result is undef. 5725 if (Q.isUndefValue(Op0) && Q.isUndefValue(Op1)) 5726 return UndefValue::get(F->getReturnType()); 5727 5728 // If shift amount is undef, assume it is zero. 5729 if (Q.isUndefValue(ShAmtArg)) 5730 return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1); 5731 5732 const APInt *ShAmtC; 5733 if (match(ShAmtArg, m_APInt(ShAmtC))) { 5734 // If there's effectively no shift, return the 1st arg or 2nd arg. 5735 APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth()); 5736 if (ShAmtC->urem(BitWidth).isNullValue()) 5737 return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1); 5738 } 5739 return nullptr; 5740 } 5741 case Intrinsic::fma: 5742 case Intrinsic::fmuladd: { 5743 Value *Op0 = Call->getArgOperand(0); 5744 Value *Op1 = Call->getArgOperand(1); 5745 Value *Op2 = Call->getArgOperand(2); 5746 if (Value *V = simplifyFPOp({ Op0, Op1, Op2 }, {}, Q)) 5747 return V; 5748 return nullptr; 5749 } 5750 default: 5751 return nullptr; 5752 } 5753 } 5754 5755 static Value *tryConstantFoldCall(CallBase *Call, const SimplifyQuery &Q) { 5756 auto *F = dyn_cast<Function>(Call->getCalledOperand()); 5757 if (!F || !canConstantFoldCallTo(Call, F)) 5758 return nullptr; 5759 5760 SmallVector<Constant *, 4> ConstantArgs; 5761 unsigned NumArgs = Call->getNumArgOperands(); 5762 ConstantArgs.reserve(NumArgs); 5763 for (auto &Arg : Call->args()) { 5764 Constant *C = dyn_cast<Constant>(&Arg); 5765 if (!C) { 5766 if (isa<MetadataAsValue>(Arg.get())) 5767 continue; 5768 return nullptr; 5769 } 5770 ConstantArgs.push_back(C); 5771 } 5772 5773 return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI); 5774 } 5775 5776 Value *llvm::SimplifyCall(CallBase *Call, const SimplifyQuery &Q) { 5777 // musttail calls can only be simplified if they are also DCEd. 5778 // As we can't guarantee this here, don't simplify them. 5779 if (Call->isMustTailCall()) 5780 return nullptr; 5781 5782 // call undef -> poison 5783 // call null -> poison 5784 Value *Callee = Call->getCalledOperand(); 5785 if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee)) 5786 return PoisonValue::get(Call->getType()); 5787 5788 if (Value *V = tryConstantFoldCall(Call, Q)) 5789 return V; 5790 5791 auto *F = dyn_cast<Function>(Callee); 5792 if (F && F->isIntrinsic()) 5793 if (Value *Ret = simplifyIntrinsic(Call, Q)) 5794 return Ret; 5795 5796 return nullptr; 5797 } 5798 5799 /// Given operands for a Freeze, see if we can fold the result. 5800 static Value *SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 5801 // Use a utility function defined in ValueTracking. 5802 if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT)) 5803 return Op0; 5804 // We have room for improvement. 5805 return nullptr; 5806 } 5807 5808 Value *llvm::SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 5809 return ::SimplifyFreezeInst(Op0, Q); 5810 } 5811 5812 /// See if we can compute a simplified version of this instruction. 5813 /// If not, this returns null. 5814 5815 Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ, 5816 OptimizationRemarkEmitter *ORE) { 5817 const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I); 5818 Value *Result; 5819 5820 switch (I->getOpcode()) { 5821 default: 5822 Result = ConstantFoldInstruction(I, Q.DL, Q.TLI); 5823 break; 5824 case Instruction::FNeg: 5825 Result = SimplifyFNegInst(I->getOperand(0), I->getFastMathFlags(), Q); 5826 break; 5827 case Instruction::FAdd: 5828 Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1), 5829 I->getFastMathFlags(), Q); 5830 break; 5831 case Instruction::Add: 5832 Result = 5833 SimplifyAddInst(I->getOperand(0), I->getOperand(1), 5834 Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 5835 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); 5836 break; 5837 case Instruction::FSub: 5838 Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1), 5839 I->getFastMathFlags(), Q); 5840 break; 5841 case Instruction::Sub: 5842 Result = 5843 SimplifySubInst(I->getOperand(0), I->getOperand(1), 5844 Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 5845 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); 5846 break; 5847 case Instruction::FMul: 5848 Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1), 5849 I->getFastMathFlags(), Q); 5850 break; 5851 case Instruction::Mul: 5852 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), Q); 5853 break; 5854 case Instruction::SDiv: 5855 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), Q); 5856 break; 5857 case Instruction::UDiv: 5858 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), Q); 5859 break; 5860 case Instruction::FDiv: 5861 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), 5862 I->getFastMathFlags(), Q); 5863 break; 5864 case Instruction::SRem: 5865 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), Q); 5866 break; 5867 case Instruction::URem: 5868 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), Q); 5869 break; 5870 case Instruction::FRem: 5871 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), 5872 I->getFastMathFlags(), Q); 5873 break; 5874 case Instruction::Shl: 5875 Result = 5876 SimplifyShlInst(I->getOperand(0), I->getOperand(1), 5877 Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 5878 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); 5879 break; 5880 case Instruction::LShr: 5881 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), 5882 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q); 5883 break; 5884 case Instruction::AShr: 5885 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), 5886 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q); 5887 break; 5888 case Instruction::And: 5889 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), Q); 5890 break; 5891 case Instruction::Or: 5892 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), Q); 5893 break; 5894 case Instruction::Xor: 5895 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), Q); 5896 break; 5897 case Instruction::ICmp: 5898 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), 5899 I->getOperand(0), I->getOperand(1), Q); 5900 break; 5901 case Instruction::FCmp: 5902 Result = 5903 SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0), 5904 I->getOperand(1), I->getFastMathFlags(), Q); 5905 break; 5906 case Instruction::Select: 5907 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), 5908 I->getOperand(2), Q); 5909 break; 5910 case Instruction::GetElementPtr: { 5911 SmallVector<Value *, 8> Ops(I->operands()); 5912 Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(), 5913 Ops, Q); 5914 break; 5915 } 5916 case Instruction::InsertValue: { 5917 InsertValueInst *IV = cast<InsertValueInst>(I); 5918 Result = SimplifyInsertValueInst(IV->getAggregateOperand(), 5919 IV->getInsertedValueOperand(), 5920 IV->getIndices(), Q); 5921 break; 5922 } 5923 case Instruction::InsertElement: { 5924 auto *IE = cast<InsertElementInst>(I); 5925 Result = SimplifyInsertElementInst(IE->getOperand(0), IE->getOperand(1), 5926 IE->getOperand(2), Q); 5927 break; 5928 } 5929 case Instruction::ExtractValue: { 5930 auto *EVI = cast<ExtractValueInst>(I); 5931 Result = SimplifyExtractValueInst(EVI->getAggregateOperand(), 5932 EVI->getIndices(), Q); 5933 break; 5934 } 5935 case Instruction::ExtractElement: { 5936 auto *EEI = cast<ExtractElementInst>(I); 5937 Result = SimplifyExtractElementInst(EEI->getVectorOperand(), 5938 EEI->getIndexOperand(), Q); 5939 break; 5940 } 5941 case Instruction::ShuffleVector: { 5942 auto *SVI = cast<ShuffleVectorInst>(I); 5943 Result = 5944 SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1), 5945 SVI->getShuffleMask(), SVI->getType(), Q); 5946 break; 5947 } 5948 case Instruction::PHI: 5949 Result = SimplifyPHINode(cast<PHINode>(I), Q); 5950 break; 5951 case Instruction::Call: { 5952 Result = SimplifyCall(cast<CallInst>(I), Q); 5953 break; 5954 } 5955 case Instruction::Freeze: 5956 Result = SimplifyFreezeInst(I->getOperand(0), Q); 5957 break; 5958 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc: 5959 #include "llvm/IR/Instruction.def" 5960 #undef HANDLE_CAST_INST 5961 Result = 5962 SimplifyCastInst(I->getOpcode(), I->getOperand(0), I->getType(), Q); 5963 break; 5964 case Instruction::Alloca: 5965 // No simplifications for Alloca and it can't be constant folded. 5966 Result = nullptr; 5967 break; 5968 } 5969 5970 /// If called on unreachable code, the above logic may report that the 5971 /// instruction simplified to itself. Make life easier for users by 5972 /// detecting that case here, returning a safe value instead. 5973 return Result == I ? UndefValue::get(I->getType()) : Result; 5974 } 5975 5976 /// Implementation of recursive simplification through an instruction's 5977 /// uses. 5978 /// 5979 /// This is the common implementation of the recursive simplification routines. 5980 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to 5981 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of 5982 /// instructions to process and attempt to simplify it using 5983 /// InstructionSimplify. Recursively visited users which could not be 5984 /// simplified themselves are to the optional UnsimplifiedUsers set for 5985 /// further processing by the caller. 5986 /// 5987 /// This routine returns 'true' only when *it* simplifies something. The passed 5988 /// in simplified value does not count toward this. 5989 static bool replaceAndRecursivelySimplifyImpl( 5990 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 5991 const DominatorTree *DT, AssumptionCache *AC, 5992 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) { 5993 bool Simplified = false; 5994 SmallSetVector<Instruction *, 8> Worklist; 5995 const DataLayout &DL = I->getModule()->getDataLayout(); 5996 5997 // If we have an explicit value to collapse to, do that round of the 5998 // simplification loop by hand initially. 5999 if (SimpleV) { 6000 for (User *U : I->users()) 6001 if (U != I) 6002 Worklist.insert(cast<Instruction>(U)); 6003 6004 // Replace the instruction with its simplified value. 6005 I->replaceAllUsesWith(SimpleV); 6006 6007 // Gracefully handle edge cases where the instruction is not wired into any 6008 // parent block. 6009 if (I->getParent() && !I->isEHPad() && !I->isTerminator() && 6010 !I->mayHaveSideEffects()) 6011 I->eraseFromParent(); 6012 } else { 6013 Worklist.insert(I); 6014 } 6015 6016 // Note that we must test the size on each iteration, the worklist can grow. 6017 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { 6018 I = Worklist[Idx]; 6019 6020 // See if this instruction simplifies. 6021 SimpleV = SimplifyInstruction(I, {DL, TLI, DT, AC}); 6022 if (!SimpleV) { 6023 if (UnsimplifiedUsers) 6024 UnsimplifiedUsers->insert(I); 6025 continue; 6026 } 6027 6028 Simplified = true; 6029 6030 // Stash away all the uses of the old instruction so we can check them for 6031 // recursive simplifications after a RAUW. This is cheaper than checking all 6032 // uses of To on the recursive step in most cases. 6033 for (User *U : I->users()) 6034 Worklist.insert(cast<Instruction>(U)); 6035 6036 // Replace the instruction with its simplified value. 6037 I->replaceAllUsesWith(SimpleV); 6038 6039 // Gracefully handle edge cases where the instruction is not wired into any 6040 // parent block. 6041 if (I->getParent() && !I->isEHPad() && !I->isTerminator() && 6042 !I->mayHaveSideEffects()) 6043 I->eraseFromParent(); 6044 } 6045 return Simplified; 6046 } 6047 6048 bool llvm::replaceAndRecursivelySimplify( 6049 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 6050 const DominatorTree *DT, AssumptionCache *AC, 6051 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) { 6052 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!"); 6053 assert(SimpleV && "Must provide a simplified value."); 6054 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC, 6055 UnsimplifiedUsers); 6056 } 6057 6058 namespace llvm { 6059 const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) { 6060 auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>(); 6061 auto *DT = DTWP ? &DTWP->getDomTree() : nullptr; 6062 auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>(); 6063 auto *TLI = TLIWP ? &TLIWP->getTLI(F) : nullptr; 6064 auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>(); 6065 auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr; 6066 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 6067 } 6068 6069 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR, 6070 const DataLayout &DL) { 6071 return {DL, &AR.TLI, &AR.DT, &AR.AC}; 6072 } 6073 6074 template <class T, class... TArgs> 6075 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM, 6076 Function &F) { 6077 auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F); 6078 auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F); 6079 auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F); 6080 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 6081 } 6082 template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &, 6083 Function &); 6084 } 6085