InstructionSimplify.cpp revision c98bd9f1a79adffe73acd337b6f7f9afa6bae078
1//===- InstructionSimplify.cpp - Fold instruction operands ----------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements routines for folding instructions into simpler forms 11// that do not require creating new instructions. This does constant folding 12// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either 13// returning a constant ("and i32 %x, 0" -> "0") or an already existing value 14// ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been 15// simplified: This is usually true and assuming it simplifies the logic (if 16// they have not been simplified then results are correct but maybe suboptimal). 17// 18//===----------------------------------------------------------------------===// 19 20#define DEBUG_TYPE "instsimplify" 21#include "llvm/Analysis/InstructionSimplify.h" 22#include "llvm/ADT/SetVector.h" 23#include "llvm/ADT/Statistic.h" 24#include "llvm/Analysis/AliasAnalysis.h" 25#include "llvm/Analysis/ConstantFolding.h" 26#include "llvm/Analysis/Dominators.h" 27#include "llvm/Analysis/ValueTracking.h" 28#include "llvm/DataLayout.h" 29#include "llvm/GlobalAlias.h" 30#include "llvm/Operator.h" 31#include "llvm/Support/ConstantRange.h" 32#include "llvm/Support/GetElementPtrTypeIterator.h" 33#include "llvm/Support/PatternMatch.h" 34#include "llvm/Support/ValueHandle.h" 35using namespace llvm; 36using namespace llvm::PatternMatch; 37 38enum { RecursionLimit = 3 }; 39 40STATISTIC(NumExpand, "Number of expansions"); 41STATISTIC(NumFactor , "Number of factorizations"); 42STATISTIC(NumReassoc, "Number of reassociations"); 43 44struct Query { 45 const DataLayout *TD; 46 const TargetLibraryInfo *TLI; 47 const DominatorTree *DT; 48 49 Query(const DataLayout *td, const TargetLibraryInfo *tli, 50 const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {} 51}; 52 53static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned); 54static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &, 55 unsigned); 56static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &, 57 unsigned); 58static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned); 59static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned); 60static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned); 61 62/// getFalse - For a boolean type, or a vector of boolean type, return false, or 63/// a vector with every element false, as appropriate for the type. 64static Constant *getFalse(Type *Ty) { 65 assert(Ty->getScalarType()->isIntegerTy(1) && 66 "Expected i1 type or a vector of i1!"); 67 return Constant::getNullValue(Ty); 68} 69 70/// getTrue - For a boolean type, or a vector of boolean type, return true, or 71/// a vector with every element true, as appropriate for the type. 72static Constant *getTrue(Type *Ty) { 73 assert(Ty->getScalarType()->isIntegerTy(1) && 74 "Expected i1 type or a vector of i1!"); 75 return Constant::getAllOnesValue(Ty); 76} 77 78/// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? 79static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, 80 Value *RHS) { 81 CmpInst *Cmp = dyn_cast<CmpInst>(V); 82 if (!Cmp) 83 return false; 84 CmpInst::Predicate CPred = Cmp->getPredicate(); 85 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); 86 if (CPred == Pred && CLHS == LHS && CRHS == RHS) 87 return true; 88 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && 89 CRHS == LHS; 90} 91 92/// ValueDominatesPHI - Does the given value dominate the specified phi node? 93static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 94 Instruction *I = dyn_cast<Instruction>(V); 95 if (!I) 96 // Arguments and constants dominate all instructions. 97 return true; 98 99 // If we are processing instructions (and/or basic blocks) that have not been 100 // fully added to a function, the parent nodes may still be null. Simply 101 // return the conservative answer in these cases. 102 if (!I->getParent() || !P->getParent() || !I->getParent()->getParent()) 103 return false; 104 105 // If we have a DominatorTree then do a precise test. 106 if (DT) { 107 if (!DT->isReachableFromEntry(P->getParent())) 108 return true; 109 if (!DT->isReachableFromEntry(I->getParent())) 110 return false; 111 return DT->dominates(I, P); 112 } 113 114 // Otherwise, if the instruction is in the entry block, and is not an invoke, 115 // then it obviously dominates all phi nodes. 116 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() && 117 !isa<InvokeInst>(I)) 118 return true; 119 120 return false; 121} 122 123/// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning 124/// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is 125/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS. 126/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)". 127/// Returns the simplified value, or null if no simplification was performed. 128static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS, 129 unsigned OpcToExpand, const Query &Q, 130 unsigned MaxRecurse) { 131 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand; 132 // Recursion is always used, so bail out at once if we already hit the limit. 133 if (!MaxRecurse--) 134 return 0; 135 136 // Check whether the expression has the form "(A op' B) op C". 137 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS)) 138 if (Op0->getOpcode() == OpcodeToExpand) { 139 // It does! Try turning it into "(A op C) op' (B op C)". 140 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS; 141 // Do "A op C" and "B op C" both simplify? 142 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) 143 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 144 // They do! Return "L op' R" if it simplifies or is already available. 145 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS. 146 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand) 147 && L == B && R == A)) { 148 ++NumExpand; 149 return LHS; 150 } 151 // Otherwise return "L op' R" if it simplifies. 152 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { 153 ++NumExpand; 154 return V; 155 } 156 } 157 } 158 159 // Check whether the expression has the form "A op (B op' C)". 160 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS)) 161 if (Op1->getOpcode() == OpcodeToExpand) { 162 // It does! Try turning it into "(A op B) op' (A op C)". 163 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1); 164 // Do "A op B" and "A op C" both simplify? 165 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) 166 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) { 167 // They do! Return "L op' R" if it simplifies or is already available. 168 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS. 169 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand) 170 && L == C && R == B)) { 171 ++NumExpand; 172 return RHS; 173 } 174 // Otherwise return "L op' R" if it simplifies. 175 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { 176 ++NumExpand; 177 return V; 178 } 179 } 180 } 181 182 return 0; 183} 184 185/// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term 186/// using the operation OpCodeToExtract. For example, when Opcode is Add and 187/// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)". 188/// Returns the simplified value, or null if no simplification was performed. 189static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS, 190 unsigned OpcToExtract, const Query &Q, 191 unsigned MaxRecurse) { 192 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract; 193 // Recursion is always used, so bail out at once if we already hit the limit. 194 if (!MaxRecurse--) 195 return 0; 196 197 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 198 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 199 200 if (!Op0 || Op0->getOpcode() != OpcodeToExtract || 201 !Op1 || Op1->getOpcode() != OpcodeToExtract) 202 return 0; 203 204 // The expression has the form "(A op' B) op (C op' D)". 205 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1); 206 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1); 207 208 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)". 209 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the 210 // commutative case, "(A op' B) op (C op' A)"? 211 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) { 212 Value *DD = A == C ? D : C; 213 // Form "A op' (B op DD)" if it simplifies completely. 214 // Does "B op DD" simplify? 215 if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) { 216 // It does! Return "A op' V" if it simplifies or is already available. 217 // If V equals B then "A op' V" is just the LHS. If V equals DD then 218 // "A op' V" is just the RHS. 219 if (V == B || V == DD) { 220 ++NumFactor; 221 return V == B ? LHS : RHS; 222 } 223 // Otherwise return "A op' V" if it simplifies. 224 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) { 225 ++NumFactor; 226 return W; 227 } 228 } 229 } 230 231 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)". 232 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the 233 // commutative case, "(A op' B) op (B op' D)"? 234 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) { 235 Value *CC = B == D ? C : D; 236 // Form "(A op CC) op' B" if it simplifies completely.. 237 // Does "A op CC" simplify? 238 if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) { 239 // It does! Return "V op' B" if it simplifies or is already available. 240 // If V equals A then "V op' B" is just the LHS. If V equals CC then 241 // "V op' B" is just the RHS. 242 if (V == A || V == CC) { 243 ++NumFactor; 244 return V == A ? LHS : RHS; 245 } 246 // Otherwise return "V op' B" if it simplifies. 247 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) { 248 ++NumFactor; 249 return W; 250 } 251 } 252 } 253 254 return 0; 255} 256 257/// SimplifyAssociativeBinOp - Generic simplifications for associative binary 258/// operations. Returns the simpler value, or null if none was found. 259static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS, 260 const Query &Q, unsigned MaxRecurse) { 261 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc; 262 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 263 264 // Recursion is always used, so bail out at once if we already hit the limit. 265 if (!MaxRecurse--) 266 return 0; 267 268 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 269 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 270 271 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 272 if (Op0 && Op0->getOpcode() == Opcode) { 273 Value *A = Op0->getOperand(0); 274 Value *B = Op0->getOperand(1); 275 Value *C = RHS; 276 277 // Does "B op C" simplify? 278 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 279 // It does! Return "A op V" if it simplifies or is already available. 280 // If V equals B then "A op V" is just the LHS. 281 if (V == B) return LHS; 282 // Otherwise return "A op V" if it simplifies. 283 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { 284 ++NumReassoc; 285 return W; 286 } 287 } 288 } 289 290 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 291 if (Op1 && Op1->getOpcode() == Opcode) { 292 Value *A = LHS; 293 Value *B = Op1->getOperand(0); 294 Value *C = Op1->getOperand(1); 295 296 // Does "A op B" simplify? 297 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { 298 // It does! Return "V op C" if it simplifies or is already available. 299 // If V equals B then "V op C" is just the RHS. 300 if (V == B) return RHS; 301 // Otherwise return "V op C" if it simplifies. 302 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { 303 ++NumReassoc; 304 return W; 305 } 306 } 307 } 308 309 // The remaining transforms require commutativity as well as associativity. 310 if (!Instruction::isCommutative(Opcode)) 311 return 0; 312 313 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 314 if (Op0 && Op0->getOpcode() == Opcode) { 315 Value *A = Op0->getOperand(0); 316 Value *B = Op0->getOperand(1); 317 Value *C = RHS; 318 319 // Does "C op A" simplify? 320 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 321 // It does! Return "V op B" if it simplifies or is already available. 322 // If V equals A then "V op B" is just the LHS. 323 if (V == A) return LHS; 324 // Otherwise return "V op B" if it simplifies. 325 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { 326 ++NumReassoc; 327 return W; 328 } 329 } 330 } 331 332 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 333 if (Op1 && Op1->getOpcode() == Opcode) { 334 Value *A = LHS; 335 Value *B = Op1->getOperand(0); 336 Value *C = Op1->getOperand(1); 337 338 // Does "C op A" simplify? 339 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 340 // It does! Return "B op V" if it simplifies or is already available. 341 // If V equals C then "B op V" is just the RHS. 342 if (V == C) return RHS; 343 // Otherwise return "B op V" if it simplifies. 344 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { 345 ++NumReassoc; 346 return W; 347 } 348 } 349 } 350 351 return 0; 352} 353 354/// ThreadBinOpOverSelect - In the case of a binary operation with a select 355/// instruction as an operand, try to simplify the binop by seeing whether 356/// evaluating it on both branches of the select results in the same value. 357/// Returns the common value if so, otherwise returns null. 358static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS, 359 const Query &Q, unsigned MaxRecurse) { 360 // Recursion is always used, so bail out at once if we already hit the limit. 361 if (!MaxRecurse--) 362 return 0; 363 364 SelectInst *SI; 365 if (isa<SelectInst>(LHS)) { 366 SI = cast<SelectInst>(LHS); 367 } else { 368 assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 369 SI = cast<SelectInst>(RHS); 370 } 371 372 // Evaluate the BinOp on the true and false branches of the select. 373 Value *TV; 374 Value *FV; 375 if (SI == LHS) { 376 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); 377 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); 378 } else { 379 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); 380 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); 381 } 382 383 // If they simplified to the same value, then return the common value. 384 // If they both failed to simplify then return null. 385 if (TV == FV) 386 return TV; 387 388 // If one branch simplified to undef, return the other one. 389 if (TV && isa<UndefValue>(TV)) 390 return FV; 391 if (FV && isa<UndefValue>(FV)) 392 return TV; 393 394 // If applying the operation did not change the true and false select values, 395 // then the result of the binop is the select itself. 396 if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 397 return SI; 398 399 // If one branch simplified and the other did not, and the simplified 400 // value is equal to the unsimplified one, return the simplified value. 401 // For example, select (cond, X, X & Z) & Z -> X & Z. 402 if ((FV && !TV) || (TV && !FV)) { 403 // Check that the simplified value has the form "X op Y" where "op" is the 404 // same as the original operation. 405 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 406 if (Simplified && Simplified->getOpcode() == Opcode) { 407 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 408 // We already know that "op" is the same as for the simplified value. See 409 // if the operands match too. If so, return the simplified value. 410 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 411 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 412 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 413 if (Simplified->getOperand(0) == UnsimplifiedLHS && 414 Simplified->getOperand(1) == UnsimplifiedRHS) 415 return Simplified; 416 if (Simplified->isCommutative() && 417 Simplified->getOperand(1) == UnsimplifiedLHS && 418 Simplified->getOperand(0) == UnsimplifiedRHS) 419 return Simplified; 420 } 421 } 422 423 return 0; 424} 425 426/// ThreadCmpOverSelect - In the case of a comparison with a select instruction, 427/// try to simplify the comparison by seeing whether both branches of the select 428/// result in the same value. Returns the common value if so, otherwise returns 429/// null. 430static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 431 Value *RHS, const Query &Q, 432 unsigned MaxRecurse) { 433 // Recursion is always used, so bail out at once if we already hit the limit. 434 if (!MaxRecurse--) 435 return 0; 436 437 // Make sure the select is on the LHS. 438 if (!isa<SelectInst>(LHS)) { 439 std::swap(LHS, RHS); 440 Pred = CmpInst::getSwappedPredicate(Pred); 441 } 442 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 443 SelectInst *SI = cast<SelectInst>(LHS); 444 Value *Cond = SI->getCondition(); 445 Value *TV = SI->getTrueValue(); 446 Value *FV = SI->getFalseValue(); 447 448 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 449 // Does "cmp TV, RHS" simplify? 450 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse); 451 if (TCmp == Cond) { 452 // It not only simplified, it simplified to the select condition. Replace 453 // it with 'true'. 454 TCmp = getTrue(Cond->getType()); 455 } else if (!TCmp) { 456 // It didn't simplify. However if "cmp TV, RHS" is equal to the select 457 // condition then we can replace it with 'true'. Otherwise give up. 458 if (!isSameCompare(Cond, Pred, TV, RHS)) 459 return 0; 460 TCmp = getTrue(Cond->getType()); 461 } 462 463 // Does "cmp FV, RHS" simplify? 464 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse); 465 if (FCmp == Cond) { 466 // It not only simplified, it simplified to the select condition. Replace 467 // it with 'false'. 468 FCmp = getFalse(Cond->getType()); 469 } else if (!FCmp) { 470 // It didn't simplify. However if "cmp FV, RHS" is equal to the select 471 // condition then we can replace it with 'false'. Otherwise give up. 472 if (!isSameCompare(Cond, Pred, FV, RHS)) 473 return 0; 474 FCmp = getFalse(Cond->getType()); 475 } 476 477 // If both sides simplified to the same value, then use it as the result of 478 // the original comparison. 479 if (TCmp == FCmp) 480 return TCmp; 481 482 // The remaining cases only make sense if the select condition has the same 483 // type as the result of the comparison, so bail out if this is not so. 484 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy()) 485 return 0; 486 // If the false value simplified to false, then the result of the compare 487 // is equal to "Cond && TCmp". This also catches the case when the false 488 // value simplified to false and the true value to true, returning "Cond". 489 if (match(FCmp, m_Zero())) 490 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse)) 491 return V; 492 // If the true value simplified to true, then the result of the compare 493 // is equal to "Cond || FCmp". 494 if (match(TCmp, m_One())) 495 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse)) 496 return V; 497 // Finally, if the false value simplified to true and the true value to 498 // false, then the result of the compare is equal to "!Cond". 499 if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 500 if (Value *V = 501 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()), 502 Q, MaxRecurse)) 503 return V; 504 505 return 0; 506} 507 508/// ThreadBinOpOverPHI - In the case of a binary operation with an operand that 509/// is a PHI instruction, try to simplify the binop by seeing whether evaluating 510/// it on the incoming phi values yields the same result for every value. If so 511/// returns the common value, otherwise returns null. 512static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS, 513 const Query &Q, unsigned MaxRecurse) { 514 // Recursion is always used, so bail out at once if we already hit the limit. 515 if (!MaxRecurse--) 516 return 0; 517 518 PHINode *PI; 519 if (isa<PHINode>(LHS)) { 520 PI = cast<PHINode>(LHS); 521 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 522 if (!ValueDominatesPHI(RHS, PI, Q.DT)) 523 return 0; 524 } else { 525 assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 526 PI = cast<PHINode>(RHS); 527 // Bail out if LHS and the phi may be mutually interdependent due to a loop. 528 if (!ValueDominatesPHI(LHS, PI, Q.DT)) 529 return 0; 530 } 531 532 // Evaluate the BinOp on the incoming phi values. 533 Value *CommonValue = 0; 534 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { 535 Value *Incoming = PI->getIncomingValue(i); 536 // If the incoming value is the phi node itself, it can safely be skipped. 537 if (Incoming == PI) continue; 538 Value *V = PI == LHS ? 539 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) : 540 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse); 541 // If the operation failed to simplify, or simplified to a different value 542 // to previously, then give up. 543 if (!V || (CommonValue && V != CommonValue)) 544 return 0; 545 CommonValue = V; 546 } 547 548 return CommonValue; 549} 550 551/// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try 552/// try to simplify the comparison by seeing whether comparing with all of the 553/// incoming phi values yields the same result every time. If so returns the 554/// common result, otherwise returns null. 555static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 556 const Query &Q, unsigned MaxRecurse) { 557 // Recursion is always used, so bail out at once if we already hit the limit. 558 if (!MaxRecurse--) 559 return 0; 560 561 // Make sure the phi is on the LHS. 562 if (!isa<PHINode>(LHS)) { 563 std::swap(LHS, RHS); 564 Pred = CmpInst::getSwappedPredicate(Pred); 565 } 566 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 567 PHINode *PI = cast<PHINode>(LHS); 568 569 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 570 if (!ValueDominatesPHI(RHS, PI, Q.DT)) 571 return 0; 572 573 // Evaluate the BinOp on the incoming phi values. 574 Value *CommonValue = 0; 575 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { 576 Value *Incoming = PI->getIncomingValue(i); 577 // If the incoming value is the phi node itself, it can safely be skipped. 578 if (Incoming == PI) continue; 579 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse); 580 // If the operation failed to simplify, or simplified to a different value 581 // to previously, then give up. 582 if (!V || (CommonValue && V != CommonValue)) 583 return 0; 584 CommonValue = V; 585 } 586 587 return CommonValue; 588} 589 590/// SimplifyAddInst - Given operands for an Add, see if we can 591/// fold the result. If not, this returns null. 592static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 593 const Query &Q, unsigned MaxRecurse) { 594 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 595 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 596 Constant *Ops[] = { CLHS, CRHS }; 597 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops, 598 Q.TD, Q.TLI); 599 } 600 601 // Canonicalize the constant to the RHS. 602 std::swap(Op0, Op1); 603 } 604 605 // X + undef -> undef 606 if (match(Op1, m_Undef())) 607 return Op1; 608 609 // X + 0 -> X 610 if (match(Op1, m_Zero())) 611 return Op0; 612 613 // X + (Y - X) -> Y 614 // (Y - X) + X -> Y 615 // Eg: X + -X -> 0 616 Value *Y = 0; 617 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 618 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 619 return Y; 620 621 // X + ~X -> -1 since ~X = -X-1 622 if (match(Op0, m_Not(m_Specific(Op1))) || 623 match(Op1, m_Not(m_Specific(Op0)))) 624 return Constant::getAllOnesValue(Op0->getType()); 625 626 /// i1 add -> xor. 627 if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 628 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 629 return V; 630 631 // Try some generic simplifications for associative operations. 632 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, 633 MaxRecurse)) 634 return V; 635 636 // Mul distributes over Add. Try some generic simplifications based on this. 637 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul, 638 Q, MaxRecurse)) 639 return V; 640 641 // Threading Add over selects and phi nodes is pointless, so don't bother. 642 // Threading over the select in "A + select(cond, B, C)" means evaluating 643 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 644 // only if B and C are equal. If B and C are equal then (since we assume 645 // that operands have already been simplified) "select(cond, B, C)" should 646 // have been simplified to the common value of B and C already. Analysing 647 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 648 // for threading over phi nodes. 649 650 return 0; 651} 652 653Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 654 const DataLayout *TD, const TargetLibraryInfo *TLI, 655 const DominatorTree *DT) { 656 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), 657 RecursionLimit); 658} 659 660/// \brief Compute the base pointer and cumulative constant offsets for V. 661/// 662/// This strips all constant offsets off of V, leaving it the base pointer, and 663/// accumulates the total constant offset applied in the returned constant. It 664/// returns 0 if V is not a pointer, and returns the constant '0' if there are 665/// no constant offsets applied. 666static Constant *stripAndComputeConstantOffsets(const DataLayout &TD, 667 Value *&V) { 668 if (!V->getType()->isPointerTy()) 669 return 0; 670 671 unsigned IntPtrWidth = TD.getPointerSizeInBits(); 672 APInt Offset = APInt::getNullValue(IntPtrWidth); 673 674 // Even though we don't look through PHI nodes, we could be called on an 675 // instruction in an unreachable block, which may be on a cycle. 676 SmallPtrSet<Value *, 4> Visited; 677 Visited.insert(V); 678 do { 679 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { 680 if (!GEP->isInBounds() || !GEP->accumulateConstantOffset(TD, Offset)) 681 break; 682 V = GEP->getPointerOperand(); 683 } else if (Operator::getOpcode(V) == Instruction::BitCast) { 684 V = cast<Operator>(V)->getOperand(0); 685 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { 686 if (GA->mayBeOverridden()) 687 break; 688 V = GA->getAliasee(); 689 } else { 690 break; 691 } 692 assert(V->getType()->isPointerTy() && "Unexpected operand type!"); 693 } while (Visited.insert(V)); 694 695 Type *IntPtrTy = TD.getIntPtrType(V->getContext()); 696 return ConstantInt::get(IntPtrTy, Offset); 697} 698 699/// \brief Compute the constant difference between two pointer values. 700/// If the difference is not a constant, returns zero. 701static Constant *computePointerDifference(const DataLayout &TD, 702 Value *LHS, Value *RHS) { 703 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS); 704 if (!LHSOffset) 705 return 0; 706 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS); 707 if (!RHSOffset) 708 return 0; 709 710 // If LHS and RHS are not related via constant offsets to the same base 711 // value, there is nothing we can do here. 712 if (LHS != RHS) 713 return 0; 714 715 // Otherwise, the difference of LHS - RHS can be computed as: 716 // LHS - RHS 717 // = (LHSOffset + Base) - (RHSOffset + Base) 718 // = LHSOffset - RHSOffset 719 return ConstantExpr::getSub(LHSOffset, RHSOffset); 720} 721 722/// SimplifySubInst - Given operands for a Sub, see if we can 723/// fold the result. If not, this returns null. 724static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 725 const Query &Q, unsigned MaxRecurse) { 726 if (Constant *CLHS = dyn_cast<Constant>(Op0)) 727 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 728 Constant *Ops[] = { CLHS, CRHS }; 729 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(), 730 Ops, Q.TD, Q.TLI); 731 } 732 733 // X - undef -> undef 734 // undef - X -> undef 735 if (match(Op0, m_Undef()) || match(Op1, m_Undef())) 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 // (X*2) - X -> X 747 // (X<<1) - X -> X 748 Value *X = 0; 749 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) || 750 match(Op0, m_Shl(m_Specific(Op1), m_One()))) 751 return Op1; 752 753 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 754 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 755 Value *Y = 0, *Z = Op1; 756 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 757 // See if "V === Y - Z" simplifies. 758 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1)) 759 // It does! Now see if "X + V" simplifies. 760 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) { 761 // It does, we successfully reassociated! 762 ++NumReassoc; 763 return W; 764 } 765 // See if "V === X - Z" simplifies. 766 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 767 // It does! Now see if "Y + V" simplifies. 768 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) { 769 // It does, we successfully reassociated! 770 ++NumReassoc; 771 return W; 772 } 773 } 774 775 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 776 // For example, X - (X + 1) -> -1 777 X = Op0; 778 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 779 // See if "V === X - Y" simplifies. 780 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 781 // It does! Now see if "V - Z" simplifies. 782 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) { 783 // It does, we successfully reassociated! 784 ++NumReassoc; 785 return W; 786 } 787 // See if "V === X - Z" simplifies. 788 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 789 // It does! Now see if "V - Y" simplifies. 790 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) { 791 // It does, we successfully reassociated! 792 ++NumReassoc; 793 return W; 794 } 795 } 796 797 // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 798 // For example, X - (X - Y) -> Y. 799 Z = Op0; 800 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 801 // See if "V === Z - X" simplifies. 802 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1)) 803 // It does! Now see if "V + Y" simplifies. 804 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) { 805 // It does, we successfully reassociated! 806 ++NumReassoc; 807 return W; 808 } 809 810 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. 811 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && 812 match(Op1, m_Trunc(m_Value(Y)))) 813 if (X->getType() == Y->getType()) 814 // See if "V === X - Y" simplifies. 815 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 816 // It does! Now see if "trunc V" simplifies. 817 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1)) 818 // It does, return the simplified "trunc V". 819 return W; 820 821 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). 822 if (Q.TD && match(Op0, m_PtrToInt(m_Value(X))) && 823 match(Op1, m_PtrToInt(m_Value(Y)))) 824 if (Constant *Result = computePointerDifference(*Q.TD, X, Y)) 825 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true); 826 827 // Mul distributes over Sub. Try some generic simplifications based on this. 828 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul, 829 Q, MaxRecurse)) 830 return V; 831 832 // i1 sub -> xor. 833 if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 834 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 835 return V; 836 837 // Threading Sub over selects and phi nodes is pointless, so don't bother. 838 // Threading over the select in "A - select(cond, B, C)" means evaluating 839 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 840 // only if B and C are equal. If B and C are equal then (since we assume 841 // that operands have already been simplified) "select(cond, B, C)" should 842 // have been simplified to the common value of B and C already. Analysing 843 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 844 // for threading over phi nodes. 845 846 return 0; 847} 848 849Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 850 const DataLayout *TD, const TargetLibraryInfo *TLI, 851 const DominatorTree *DT) { 852 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), 853 RecursionLimit); 854} 855 856/// Given operands for an FAdd, see if we can fold the result. If not, this 857/// returns null. 858static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 859 const Query &Q, unsigned MaxRecurse) { 860 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 861 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 862 Constant *Ops[] = { CLHS, CRHS }; 863 return ConstantFoldInstOperands(Instruction::FAdd, CLHS->getType(), 864 Ops, Q.TD, Q.TLI); 865 } 866 867 // Canonicalize the constant to the RHS. 868 std::swap(Op0, Op1); 869 } 870 871 // fadd X, -0 ==> X 872 if (match(Op1, m_NegZero())) 873 return Op0; 874 875 // fadd X, 0 ==> X, when we know X is not -0 876 if (match(Op1, m_Zero()) && 877 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0))) 878 return Op0; 879 880 // fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0 881 // where nnan and ninf have to occur at least once somewhere in this 882 // expression 883 Value *SubOp = 0; 884 if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0)))) 885 SubOp = Op1; 886 else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1)))) 887 SubOp = Op0; 888 if (SubOp) { 889 Instruction *FSub = cast<Instruction>(SubOp); 890 if ((FMF.noNaNs() || FSub->hasNoNaNs()) && 891 (FMF.noInfs() || FSub->hasNoInfs())) 892 return Constant::getNullValue(Op0->getType()); 893 } 894 895 return 0; 896} 897 898/// Given operands for an FSub, see if we can fold the result. If not, this 899/// returns null. 900static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 901 const Query &Q, unsigned MaxRecurse) { 902 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 903 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 904 Constant *Ops[] = { CLHS, CRHS }; 905 return ConstantFoldInstOperands(Instruction::FSub, CLHS->getType(), 906 Ops, Q.TD, Q.TLI); 907 } 908 } 909 910 // fsub X, 0 ==> X 911 if (match(Op1, m_Zero())) 912 return Op0; 913 914 // fsub X, -0 ==> X, when we know X is not -0 915 if (match(Op1, m_NegZero()) && 916 (FMF.noSignedZeros() || CannotBeNegativeZero(Op0))) 917 return Op0; 918 919 // fsub 0, (fsub -0.0, X) ==> X 920 Value *X; 921 if (match(Op0, m_AnyZero())) { 922 if (match(Op1, m_FSub(m_NegZero(), m_Value(X)))) 923 return X; 924 if (FMF.noSignedZeros() && match(Op1, m_FSub(m_AnyZero(), m_Value(X)))) 925 return X; 926 } 927 928 // fsub nnan ninf x, x ==> 0.0 929 if (FMF.noNaNs() && FMF.noInfs() && Op0 == Op1) 930 return Constant::getNullValue(Op0->getType()); 931 932 return 0; 933} 934 935/// Given the operands for an FMul, see if we can fold the result 936static Value *SimplifyFMulInst(Value *Op0, Value *Op1, 937 FastMathFlags FMF, 938 const Query &Q, 939 unsigned MaxRecurse) { 940 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 941 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 942 Constant *Ops[] = { CLHS, CRHS }; 943 return ConstantFoldInstOperands(Instruction::FMul, CLHS->getType(), 944 Ops, Q.TD, Q.TLI); 945 } 946 947 // Canonicalize the constant to the RHS. 948 std::swap(Op0, Op1); 949 } 950 951 // fmul X, 1.0 ==> X 952 if (match(Op1, m_FPOne())) 953 return Op0; 954 955 // fmul nnan nsz X, 0 ==> 0 956 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero())) 957 return Op1; 958 959 return 0; 960} 961 962/// SimplifyMulInst - Given operands for a Mul, see if we can 963/// fold the result. If not, this returns null. 964static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q, 965 unsigned MaxRecurse) { 966 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 967 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 968 Constant *Ops[] = { CLHS, CRHS }; 969 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(), 970 Ops, Q.TD, Q.TLI); 971 } 972 973 // Canonicalize the constant to the RHS. 974 std::swap(Op0, Op1); 975 } 976 977 // X * undef -> 0 978 if (match(Op1, m_Undef())) 979 return Constant::getNullValue(Op0->getType()); 980 981 // X * 0 -> 0 982 if (match(Op1, m_Zero())) 983 return Op1; 984 985 // X * 1 -> X 986 if (match(Op1, m_One())) 987 return Op0; 988 989 // (X / Y) * Y -> X if the division is exact. 990 Value *X = 0; 991 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y 992 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y) 993 return X; 994 995 // i1 mul -> and. 996 if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 997 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1)) 998 return V; 999 1000 // Try some generic simplifications for associative operations. 1001 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, 1002 MaxRecurse)) 1003 return V; 1004 1005 // Mul distributes over Add. Try some generic simplifications based on this. 1006 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add, 1007 Q, MaxRecurse)) 1008 return V; 1009 1010 // If the operation is with the result of a select instruction, check whether 1011 // operating on either branch of the select always yields the same value. 1012 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1013 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, 1014 MaxRecurse)) 1015 return V; 1016 1017 // If the operation is with the result of a phi instruction, check whether 1018 // operating on all incoming values of the phi always yields the same value. 1019 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1020 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, 1021 MaxRecurse)) 1022 return V; 1023 1024 return 0; 1025} 1026 1027Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 1028 const DataLayout *TD, const TargetLibraryInfo *TLI, 1029 const DominatorTree *DT) { 1030 return ::SimplifyFAddInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit); 1031} 1032 1033Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 1034 const DataLayout *TD, const TargetLibraryInfo *TLI, 1035 const DominatorTree *DT) { 1036 return ::SimplifyFSubInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit); 1037} 1038 1039Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, 1040 FastMathFlags FMF, 1041 const DataLayout *TD, 1042 const TargetLibraryInfo *TLI, 1043 const DominatorTree *DT) { 1044 return ::SimplifyFMulInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit); 1045} 1046 1047Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout *TD, 1048 const TargetLibraryInfo *TLI, 1049 const DominatorTree *DT) { 1050 return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1051} 1052 1053/// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can 1054/// fold the result. If not, this returns null. 1055static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1056 const Query &Q, unsigned MaxRecurse) { 1057 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 1058 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 1059 Constant *Ops[] = { C0, C1 }; 1060 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); 1061 } 1062 } 1063 1064 bool isSigned = Opcode == Instruction::SDiv; 1065 1066 // X / undef -> undef 1067 if (match(Op1, m_Undef())) 1068 return Op1; 1069 1070 // undef / X -> 0 1071 if (match(Op0, m_Undef())) 1072 return Constant::getNullValue(Op0->getType()); 1073 1074 // 0 / X -> 0, we don't need to preserve faults! 1075 if (match(Op0, m_Zero())) 1076 return Op0; 1077 1078 // X / 1 -> X 1079 if (match(Op1, m_One())) 1080 return Op0; 1081 1082 if (Op0->getType()->isIntegerTy(1)) 1083 // It can't be division by zero, hence it must be division by one. 1084 return Op0; 1085 1086 // X / X -> 1 1087 if (Op0 == Op1) 1088 return ConstantInt::get(Op0->getType(), 1); 1089 1090 // (X * Y) / Y -> X if the multiplication does not overflow. 1091 Value *X = 0, *Y = 0; 1092 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) { 1093 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1 1094 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0); 1095 // If the Mul knows it does not overflow, then we are good to go. 1096 if ((isSigned && Mul->hasNoSignedWrap()) || 1097 (!isSigned && Mul->hasNoUnsignedWrap())) 1098 return X; 1099 // If X has the form X = A / Y then X * Y cannot overflow. 1100 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X)) 1101 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y) 1102 return X; 1103 } 1104 1105 // (X rem Y) / Y -> 0 1106 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || 1107 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1))))) 1108 return Constant::getNullValue(Op0->getType()); 1109 1110 // If the operation is with the result of a select instruction, check whether 1111 // operating on either branch of the select always yields the same value. 1112 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1113 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1114 return V; 1115 1116 // If the operation is with the result of a phi instruction, check whether 1117 // operating on all incoming values of the phi always yields the same value. 1118 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1119 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1120 return V; 1121 1122 return 0; 1123} 1124 1125/// SimplifySDivInst - Given operands for an SDiv, see if we can 1126/// fold the result. If not, this returns null. 1127static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q, 1128 unsigned MaxRecurse) { 1129 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse)) 1130 return V; 1131 1132 return 0; 1133} 1134 1135Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout *TD, 1136 const TargetLibraryInfo *TLI, 1137 const DominatorTree *DT) { 1138 return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1139} 1140 1141/// SimplifyUDivInst - Given operands for a UDiv, see if we can 1142/// fold the result. If not, this returns null. 1143static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q, 1144 unsigned MaxRecurse) { 1145 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse)) 1146 return V; 1147 1148 return 0; 1149} 1150 1151Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout *TD, 1152 const TargetLibraryInfo *TLI, 1153 const DominatorTree *DT) { 1154 return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1155} 1156 1157static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q, 1158 unsigned) { 1159 // undef / X -> undef (the undef could be a snan). 1160 if (match(Op0, m_Undef())) 1161 return Op0; 1162 1163 // X / undef -> undef 1164 if (match(Op1, m_Undef())) 1165 return Op1; 1166 1167 return 0; 1168} 1169 1170Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const DataLayout *TD, 1171 const TargetLibraryInfo *TLI, 1172 const DominatorTree *DT) { 1173 return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1174} 1175 1176/// SimplifyRem - Given operands for an SRem or URem, see if we can 1177/// fold the result. If not, this returns null. 1178static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1179 const Query &Q, unsigned MaxRecurse) { 1180 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 1181 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 1182 Constant *Ops[] = { C0, C1 }; 1183 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); 1184 } 1185 } 1186 1187 // X % undef -> undef 1188 if (match(Op1, m_Undef())) 1189 return Op1; 1190 1191 // undef % X -> 0 1192 if (match(Op0, m_Undef())) 1193 return Constant::getNullValue(Op0->getType()); 1194 1195 // 0 % X -> 0, we don't need to preserve faults! 1196 if (match(Op0, m_Zero())) 1197 return Op0; 1198 1199 // X % 0 -> undef, we don't need to preserve faults! 1200 if (match(Op1, m_Zero())) 1201 return UndefValue::get(Op0->getType()); 1202 1203 // X % 1 -> 0 1204 if (match(Op1, m_One())) 1205 return Constant::getNullValue(Op0->getType()); 1206 1207 if (Op0->getType()->isIntegerTy(1)) 1208 // It can't be remainder by zero, hence it must be remainder by one. 1209 return Constant::getNullValue(Op0->getType()); 1210 1211 // X % X -> 0 1212 if (Op0 == Op1) 1213 return Constant::getNullValue(Op0->getType()); 1214 1215 // If the operation is with the result of a select instruction, check whether 1216 // operating on either branch of the select always yields the same value. 1217 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1218 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1219 return V; 1220 1221 // If the operation is with the result of a phi instruction, check whether 1222 // operating on all incoming values of the phi always yields the same value. 1223 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1224 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1225 return V; 1226 1227 return 0; 1228} 1229 1230/// SimplifySRemInst - Given operands for an SRem, see if we can 1231/// fold the result. If not, this returns null. 1232static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q, 1233 unsigned MaxRecurse) { 1234 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse)) 1235 return V; 1236 1237 return 0; 1238} 1239 1240Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout *TD, 1241 const TargetLibraryInfo *TLI, 1242 const DominatorTree *DT) { 1243 return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1244} 1245 1246/// SimplifyURemInst - Given operands for a URem, see if we can 1247/// fold the result. If not, this returns null. 1248static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q, 1249 unsigned MaxRecurse) { 1250 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse)) 1251 return V; 1252 1253 return 0; 1254} 1255 1256Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout *TD, 1257 const TargetLibraryInfo *TLI, 1258 const DominatorTree *DT) { 1259 return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1260} 1261 1262static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &, 1263 unsigned) { 1264 // undef % X -> undef (the undef could be a snan). 1265 if (match(Op0, m_Undef())) 1266 return Op0; 1267 1268 // X % undef -> undef 1269 if (match(Op1, m_Undef())) 1270 return Op1; 1271 1272 return 0; 1273} 1274 1275Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const DataLayout *TD, 1276 const TargetLibraryInfo *TLI, 1277 const DominatorTree *DT) { 1278 return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1279} 1280 1281/// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can 1282/// fold the result. If not, this returns null. 1283static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1, 1284 const Query &Q, unsigned MaxRecurse) { 1285 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 1286 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 1287 Constant *Ops[] = { C0, C1 }; 1288 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); 1289 } 1290 } 1291 1292 // 0 shift by X -> 0 1293 if (match(Op0, m_Zero())) 1294 return Op0; 1295 1296 // X shift by 0 -> X 1297 if (match(Op1, m_Zero())) 1298 return Op0; 1299 1300 // X shift by undef -> undef because it may shift by the bitwidth. 1301 if (match(Op1, m_Undef())) 1302 return Op1; 1303 1304 // Shifting by the bitwidth or more is undefined. 1305 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) 1306 if (CI->getValue().getLimitedValue() >= 1307 Op0->getType()->getScalarSizeInBits()) 1308 return UndefValue::get(Op0->getType()); 1309 1310 // If the operation is with the result of a select instruction, check whether 1311 // operating on either branch of the select always yields the same value. 1312 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1313 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1314 return V; 1315 1316 // If the operation is with the result of a phi instruction, check whether 1317 // operating on all incoming values of the phi always yields the same value. 1318 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1319 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1320 return V; 1321 1322 return 0; 1323} 1324 1325/// SimplifyShlInst - Given operands for an Shl, see if we can 1326/// fold the result. If not, this returns null. 1327static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1328 const Query &Q, unsigned MaxRecurse) { 1329 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse)) 1330 return V; 1331 1332 // undef << X -> 0 1333 if (match(Op0, m_Undef())) 1334 return Constant::getNullValue(Op0->getType()); 1335 1336 // (X >> A) << A -> X 1337 Value *X; 1338 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) 1339 return X; 1340 return 0; 1341} 1342 1343Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1344 const DataLayout *TD, const TargetLibraryInfo *TLI, 1345 const DominatorTree *DT) { 1346 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), 1347 RecursionLimit); 1348} 1349 1350/// SimplifyLShrInst - Given operands for an LShr, see if we can 1351/// fold the result. If not, this returns null. 1352static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1353 const Query &Q, unsigned MaxRecurse) { 1354 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse)) 1355 return V; 1356 1357 // undef >>l X -> 0 1358 if (match(Op0, m_Undef())) 1359 return Constant::getNullValue(Op0->getType()); 1360 1361 // (X << A) >> A -> X 1362 Value *X; 1363 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && 1364 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap()) 1365 return X; 1366 1367 return 0; 1368} 1369 1370Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1371 const DataLayout *TD, 1372 const TargetLibraryInfo *TLI, 1373 const DominatorTree *DT) { 1374 return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT), 1375 RecursionLimit); 1376} 1377 1378/// SimplifyAShrInst - Given operands for an AShr, see if we can 1379/// fold the result. If not, this returns null. 1380static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1381 const Query &Q, unsigned MaxRecurse) { 1382 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse)) 1383 return V; 1384 1385 // all ones >>a X -> all ones 1386 if (match(Op0, m_AllOnes())) 1387 return Op0; 1388 1389 // undef >>a X -> all ones 1390 if (match(Op0, m_Undef())) 1391 return Constant::getAllOnesValue(Op0->getType()); 1392 1393 // (X << A) >> A -> X 1394 Value *X; 1395 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && 1396 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap()) 1397 return X; 1398 1399 return 0; 1400} 1401 1402Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1403 const DataLayout *TD, 1404 const TargetLibraryInfo *TLI, 1405 const DominatorTree *DT) { 1406 return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT), 1407 RecursionLimit); 1408} 1409 1410/// SimplifyAndInst - Given operands for an And, see if we can 1411/// fold the result. If not, this returns null. 1412static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q, 1413 unsigned MaxRecurse) { 1414 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1415 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1416 Constant *Ops[] = { CLHS, CRHS }; 1417 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(), 1418 Ops, Q.TD, Q.TLI); 1419 } 1420 1421 // Canonicalize the constant to the RHS. 1422 std::swap(Op0, Op1); 1423 } 1424 1425 // X & undef -> 0 1426 if (match(Op1, m_Undef())) 1427 return Constant::getNullValue(Op0->getType()); 1428 1429 // X & X = X 1430 if (Op0 == Op1) 1431 return Op0; 1432 1433 // X & 0 = 0 1434 if (match(Op1, m_Zero())) 1435 return Op1; 1436 1437 // X & -1 = X 1438 if (match(Op1, m_AllOnes())) 1439 return Op0; 1440 1441 // A & ~A = ~A & A = 0 1442 if (match(Op0, m_Not(m_Specific(Op1))) || 1443 match(Op1, m_Not(m_Specific(Op0)))) 1444 return Constant::getNullValue(Op0->getType()); 1445 1446 // (A | ?) & A = A 1447 Value *A = 0, *B = 0; 1448 if (match(Op0, m_Or(m_Value(A), m_Value(B))) && 1449 (A == Op1 || B == Op1)) 1450 return Op1; 1451 1452 // A & (A | ?) = A 1453 if (match(Op1, m_Or(m_Value(A), m_Value(B))) && 1454 (A == Op0 || B == Op0)) 1455 return Op0; 1456 1457 // A & (-A) = A if A is a power of two or zero. 1458 if (match(Op0, m_Neg(m_Specific(Op1))) || 1459 match(Op1, m_Neg(m_Specific(Op0)))) { 1460 if (isKnownToBeAPowerOfTwo(Op0, /*OrZero*/true)) 1461 return Op0; 1462 if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/true)) 1463 return Op1; 1464 } 1465 1466 // Try some generic simplifications for associative operations. 1467 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, 1468 MaxRecurse)) 1469 return V; 1470 1471 // And distributes over Or. Try some generic simplifications based on this. 1472 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or, 1473 Q, MaxRecurse)) 1474 return V; 1475 1476 // And distributes over Xor. Try some generic simplifications based on this. 1477 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor, 1478 Q, MaxRecurse)) 1479 return V; 1480 1481 // Or distributes over And. Try some generic simplifications based on this. 1482 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or, 1483 Q, MaxRecurse)) 1484 return V; 1485 1486 // If the operation is with the result of a select instruction, check whether 1487 // operating on either branch of the select always yields the same value. 1488 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1489 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q, 1490 MaxRecurse)) 1491 return V; 1492 1493 // If the operation is with the result of a phi instruction, check whether 1494 // operating on all incoming values of the phi always yields the same value. 1495 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1496 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q, 1497 MaxRecurse)) 1498 return V; 1499 1500 return 0; 1501} 1502 1503Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout *TD, 1504 const TargetLibraryInfo *TLI, 1505 const DominatorTree *DT) { 1506 return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1507} 1508 1509/// SimplifyOrInst - Given operands for an Or, see if we can 1510/// fold the result. If not, this returns null. 1511static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q, 1512 unsigned MaxRecurse) { 1513 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1514 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1515 Constant *Ops[] = { CLHS, CRHS }; 1516 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(), 1517 Ops, Q.TD, Q.TLI); 1518 } 1519 1520 // Canonicalize the constant to the RHS. 1521 std::swap(Op0, Op1); 1522 } 1523 1524 // X | undef -> -1 1525 if (match(Op1, m_Undef())) 1526 return Constant::getAllOnesValue(Op0->getType()); 1527 1528 // X | X = X 1529 if (Op0 == Op1) 1530 return Op0; 1531 1532 // X | 0 = X 1533 if (match(Op1, m_Zero())) 1534 return Op0; 1535 1536 // X | -1 = -1 1537 if (match(Op1, m_AllOnes())) 1538 return Op1; 1539 1540 // A | ~A = ~A | A = -1 1541 if (match(Op0, m_Not(m_Specific(Op1))) || 1542 match(Op1, m_Not(m_Specific(Op0)))) 1543 return Constant::getAllOnesValue(Op0->getType()); 1544 1545 // (A & ?) | A = A 1546 Value *A = 0, *B = 0; 1547 if (match(Op0, m_And(m_Value(A), m_Value(B))) && 1548 (A == Op1 || B == Op1)) 1549 return Op1; 1550 1551 // A | (A & ?) = A 1552 if (match(Op1, m_And(m_Value(A), m_Value(B))) && 1553 (A == Op0 || B == Op0)) 1554 return Op0; 1555 1556 // ~(A & ?) | A = -1 1557 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) && 1558 (A == Op1 || B == Op1)) 1559 return Constant::getAllOnesValue(Op1->getType()); 1560 1561 // A | ~(A & ?) = -1 1562 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) && 1563 (A == Op0 || B == Op0)) 1564 return Constant::getAllOnesValue(Op0->getType()); 1565 1566 // Try some generic simplifications for associative operations. 1567 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, 1568 MaxRecurse)) 1569 return V; 1570 1571 // Or distributes over And. Try some generic simplifications based on this. 1572 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q, 1573 MaxRecurse)) 1574 return V; 1575 1576 // And distributes over Or. Try some generic simplifications based on this. 1577 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And, 1578 Q, MaxRecurse)) 1579 return V; 1580 1581 // If the operation is with the result of a select instruction, check whether 1582 // operating on either branch of the select always yields the same value. 1583 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1584 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, 1585 MaxRecurse)) 1586 return V; 1587 1588 // If the operation is with the result of a phi instruction, check whether 1589 // operating on all incoming values of the phi always yields the same value. 1590 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1591 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 1592 return V; 1593 1594 return 0; 1595} 1596 1597Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout *TD, 1598 const TargetLibraryInfo *TLI, 1599 const DominatorTree *DT) { 1600 return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1601} 1602 1603/// SimplifyXorInst - Given operands for a Xor, see if we can 1604/// fold the result. If not, this returns null. 1605static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q, 1606 unsigned MaxRecurse) { 1607 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1608 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1609 Constant *Ops[] = { CLHS, CRHS }; 1610 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(), 1611 Ops, Q.TD, Q.TLI); 1612 } 1613 1614 // Canonicalize the constant to the RHS. 1615 std::swap(Op0, Op1); 1616 } 1617 1618 // A ^ undef -> undef 1619 if (match(Op1, m_Undef())) 1620 return Op1; 1621 1622 // A ^ 0 = A 1623 if (match(Op1, m_Zero())) 1624 return Op0; 1625 1626 // A ^ A = 0 1627 if (Op0 == Op1) 1628 return Constant::getNullValue(Op0->getType()); 1629 1630 // A ^ ~A = ~A ^ A = -1 1631 if (match(Op0, m_Not(m_Specific(Op1))) || 1632 match(Op1, m_Not(m_Specific(Op0)))) 1633 return Constant::getAllOnesValue(Op0->getType()); 1634 1635 // Try some generic simplifications for associative operations. 1636 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, 1637 MaxRecurse)) 1638 return V; 1639 1640 // And distributes over Xor. Try some generic simplifications based on this. 1641 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And, 1642 Q, MaxRecurse)) 1643 return V; 1644 1645 // Threading Xor over selects and phi nodes is pointless, so don't bother. 1646 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 1647 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 1648 // only if B and C are equal. If B and C are equal then (since we assume 1649 // that operands have already been simplified) "select(cond, B, C)" should 1650 // have been simplified to the common value of B and C already. Analysing 1651 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 1652 // for threading over phi nodes. 1653 1654 return 0; 1655} 1656 1657Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const DataLayout *TD, 1658 const TargetLibraryInfo *TLI, 1659 const DominatorTree *DT) { 1660 return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1661} 1662 1663static Type *GetCompareTy(Value *Op) { 1664 return CmpInst::makeCmpResultType(Op->getType()); 1665} 1666 1667/// ExtractEquivalentCondition - Rummage around inside V looking for something 1668/// equivalent to the comparison "LHS Pred RHS". Return such a value if found, 1669/// otherwise return null. Helper function for analyzing max/min idioms. 1670static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 1671 Value *LHS, Value *RHS) { 1672 SelectInst *SI = dyn_cast<SelectInst>(V); 1673 if (!SI) 1674 return 0; 1675 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 1676 if (!Cmp) 1677 return 0; 1678 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 1679 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 1680 return Cmp; 1681 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 1682 LHS == CmpRHS && RHS == CmpLHS) 1683 return Cmp; 1684 return 0; 1685} 1686 1687static Constant *computePointerICmp(const DataLayout &TD, 1688 CmpInst::Predicate Pred, 1689 Value *LHS, Value *RHS) { 1690 // We can only fold certain predicates on pointer comparisons. 1691 switch (Pred) { 1692 default: 1693 return 0; 1694 1695 // Equality comaprisons are easy to fold. 1696 case CmpInst::ICMP_EQ: 1697 case CmpInst::ICMP_NE: 1698 break; 1699 1700 // We can only handle unsigned relational comparisons because 'inbounds' on 1701 // a GEP only protects against unsigned wrapping. 1702 case CmpInst::ICMP_UGT: 1703 case CmpInst::ICMP_UGE: 1704 case CmpInst::ICMP_ULT: 1705 case CmpInst::ICMP_ULE: 1706 // However, we have to switch them to their signed variants to handle 1707 // negative indices from the base pointer. 1708 Pred = ICmpInst::getSignedPredicate(Pred); 1709 break; 1710 } 1711 1712 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS); 1713 if (!LHSOffset) 1714 return 0; 1715 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS); 1716 if (!RHSOffset) 1717 return 0; 1718 1719 // If LHS and RHS are not related via constant offsets to the same base 1720 // value, there is nothing we can do here. 1721 if (LHS != RHS) 1722 return 0; 1723 1724 return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset); 1725} 1726 1727/// SimplifyICmpInst - Given operands for an ICmpInst, see if we can 1728/// fold the result. If not, this returns null. 1729static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 1730 const Query &Q, unsigned MaxRecurse) { 1731 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 1732 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 1733 1734 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 1735 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 1736 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI); 1737 1738 // If we have a constant, make sure it is on the RHS. 1739 std::swap(LHS, RHS); 1740 Pred = CmpInst::getSwappedPredicate(Pred); 1741 } 1742 1743 Type *ITy = GetCompareTy(LHS); // The return type. 1744 Type *OpTy = LHS->getType(); // The operand type. 1745 1746 // icmp X, X -> true/false 1747 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false 1748 // because X could be 0. 1749 if (LHS == RHS || isa<UndefValue>(RHS)) 1750 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 1751 1752 // Special case logic when the operands have i1 type. 1753 if (OpTy->getScalarType()->isIntegerTy(1)) { 1754 switch (Pred) { 1755 default: break; 1756 case ICmpInst::ICMP_EQ: 1757 // X == 1 -> X 1758 if (match(RHS, m_One())) 1759 return LHS; 1760 break; 1761 case ICmpInst::ICMP_NE: 1762 // X != 0 -> X 1763 if (match(RHS, m_Zero())) 1764 return LHS; 1765 break; 1766 case ICmpInst::ICMP_UGT: 1767 // X >u 0 -> X 1768 if (match(RHS, m_Zero())) 1769 return LHS; 1770 break; 1771 case ICmpInst::ICMP_UGE: 1772 // X >=u 1 -> X 1773 if (match(RHS, m_One())) 1774 return LHS; 1775 break; 1776 case ICmpInst::ICMP_SLT: 1777 // X <s 0 -> X 1778 if (match(RHS, m_Zero())) 1779 return LHS; 1780 break; 1781 case ICmpInst::ICMP_SLE: 1782 // X <=s -1 -> X 1783 if (match(RHS, m_One())) 1784 return LHS; 1785 break; 1786 } 1787 } 1788 1789 // icmp <object*>, <object*/null> - Different identified objects have 1790 // different addresses (unless null), and what's more the address of an 1791 // identified local is never equal to another argument (again, barring null). 1792 // Note that generalizing to the case where LHS is a global variable address 1793 // or null is pointless, since if both LHS and RHS are constants then we 1794 // already constant folded the compare, and if only one of them is then we 1795 // moved it to RHS already. 1796 Value *LHSPtr = LHS->stripPointerCasts(); 1797 Value *RHSPtr = RHS->stripPointerCasts(); 1798 if (LHSPtr == RHSPtr) 1799 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 1800 1801 // Be more aggressive about stripping pointer adjustments when checking a 1802 // comparison of an alloca address to another object. We can rip off all 1803 // inbounds GEP operations, even if they are variable. 1804 LHSPtr = LHSPtr->stripInBoundsOffsets(); 1805 if (llvm::isIdentifiedObject(LHSPtr)) { 1806 RHSPtr = RHSPtr->stripInBoundsOffsets(); 1807 if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) { 1808 // If both sides are different identified objects, they aren't equal 1809 // unless they're null. 1810 if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) && 1811 Pred == CmpInst::ICMP_EQ) 1812 return ConstantInt::get(ITy, false); 1813 1814 // A local identified object (alloca or noalias call) can't equal any 1815 // incoming argument, unless they're both null or they belong to 1816 // different functions. The latter happens during inlining. 1817 if (Instruction *LHSInst = dyn_cast<Instruction>(LHSPtr)) 1818 if (Argument *RHSArg = dyn_cast<Argument>(RHSPtr)) 1819 if (LHSInst->getParent()->getParent() == RHSArg->getParent() && 1820 Pred == CmpInst::ICMP_EQ) 1821 return ConstantInt::get(ITy, false); 1822 } 1823 1824 // Assume that the constant null is on the right. 1825 if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) { 1826 if (Pred == CmpInst::ICMP_EQ) 1827 return ConstantInt::get(ITy, false); 1828 else if (Pred == CmpInst::ICMP_NE) 1829 return ConstantInt::get(ITy, true); 1830 } 1831 } else if (Argument *LHSArg = dyn_cast<Argument>(LHSPtr)) { 1832 RHSPtr = RHSPtr->stripInBoundsOffsets(); 1833 // An alloca can't be equal to an argument unless they come from separate 1834 // functions via inlining. 1835 if (AllocaInst *RHSInst = dyn_cast<AllocaInst>(RHSPtr)) { 1836 if (LHSArg->getParent() == RHSInst->getParent()->getParent()) { 1837 if (Pred == CmpInst::ICMP_EQ) 1838 return ConstantInt::get(ITy, false); 1839 else if (Pred == CmpInst::ICMP_NE) 1840 return ConstantInt::get(ITy, true); 1841 } 1842 } 1843 } 1844 1845 // If we are comparing with zero then try hard since this is a common case. 1846 if (match(RHS, m_Zero())) { 1847 bool LHSKnownNonNegative, LHSKnownNegative; 1848 switch (Pred) { 1849 default: llvm_unreachable("Unknown ICmp predicate!"); 1850 case ICmpInst::ICMP_ULT: 1851 return getFalse(ITy); 1852 case ICmpInst::ICMP_UGE: 1853 return getTrue(ITy); 1854 case ICmpInst::ICMP_EQ: 1855 case ICmpInst::ICMP_ULE: 1856 if (isKnownNonZero(LHS, Q.TD)) 1857 return getFalse(ITy); 1858 break; 1859 case ICmpInst::ICMP_NE: 1860 case ICmpInst::ICMP_UGT: 1861 if (isKnownNonZero(LHS, Q.TD)) 1862 return getTrue(ITy); 1863 break; 1864 case ICmpInst::ICMP_SLT: 1865 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1866 if (LHSKnownNegative) 1867 return getTrue(ITy); 1868 if (LHSKnownNonNegative) 1869 return getFalse(ITy); 1870 break; 1871 case ICmpInst::ICMP_SLE: 1872 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1873 if (LHSKnownNegative) 1874 return getTrue(ITy); 1875 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD)) 1876 return getFalse(ITy); 1877 break; 1878 case ICmpInst::ICMP_SGE: 1879 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1880 if (LHSKnownNegative) 1881 return getFalse(ITy); 1882 if (LHSKnownNonNegative) 1883 return getTrue(ITy); 1884 break; 1885 case ICmpInst::ICMP_SGT: 1886 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1887 if (LHSKnownNegative) 1888 return getFalse(ITy); 1889 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD)) 1890 return getTrue(ITy); 1891 break; 1892 } 1893 } 1894 1895 // See if we are doing a comparison with a constant integer. 1896 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 1897 // Rule out tautological comparisons (eg., ult 0 or uge 0). 1898 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue()); 1899 if (RHS_CR.isEmptySet()) 1900 return ConstantInt::getFalse(CI->getContext()); 1901 if (RHS_CR.isFullSet()) 1902 return ConstantInt::getTrue(CI->getContext()); 1903 1904 // Many binary operators with constant RHS have easy to compute constant 1905 // range. Use them to check whether the comparison is a tautology. 1906 uint32_t Width = CI->getBitWidth(); 1907 APInt Lower = APInt(Width, 0); 1908 APInt Upper = APInt(Width, 0); 1909 ConstantInt *CI2; 1910 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) { 1911 // 'urem x, CI2' produces [0, CI2). 1912 Upper = CI2->getValue(); 1913 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) { 1914 // 'srem x, CI2' produces (-|CI2|, |CI2|). 1915 Upper = CI2->getValue().abs(); 1916 Lower = (-Upper) + 1; 1917 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) { 1918 // 'udiv CI2, x' produces [0, CI2]. 1919 Upper = CI2->getValue() + 1; 1920 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) { 1921 // 'udiv x, CI2' produces [0, UINT_MAX / CI2]. 1922 APInt NegOne = APInt::getAllOnesValue(Width); 1923 if (!CI2->isZero()) 1924 Upper = NegOne.udiv(CI2->getValue()) + 1; 1925 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) { 1926 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]. 1927 APInt IntMin = APInt::getSignedMinValue(Width); 1928 APInt IntMax = APInt::getSignedMaxValue(Width); 1929 APInt Val = CI2->getValue().abs(); 1930 if (!Val.isMinValue()) { 1931 Lower = IntMin.sdiv(Val); 1932 Upper = IntMax.sdiv(Val) + 1; 1933 } 1934 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) { 1935 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2]. 1936 APInt NegOne = APInt::getAllOnesValue(Width); 1937 if (CI2->getValue().ult(Width)) 1938 Upper = NegOne.lshr(CI2->getValue()) + 1; 1939 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) { 1940 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2]. 1941 APInt IntMin = APInt::getSignedMinValue(Width); 1942 APInt IntMax = APInt::getSignedMaxValue(Width); 1943 if (CI2->getValue().ult(Width)) { 1944 Lower = IntMin.ashr(CI2->getValue()); 1945 Upper = IntMax.ashr(CI2->getValue()) + 1; 1946 } 1947 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) { 1948 // 'or x, CI2' produces [CI2, UINT_MAX]. 1949 Lower = CI2->getValue(); 1950 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) { 1951 // 'and x, CI2' produces [0, CI2]. 1952 Upper = CI2->getValue() + 1; 1953 } 1954 if (Lower != Upper) { 1955 ConstantRange LHS_CR = ConstantRange(Lower, Upper); 1956 if (RHS_CR.contains(LHS_CR)) 1957 return ConstantInt::getTrue(RHS->getContext()); 1958 if (RHS_CR.inverse().contains(LHS_CR)) 1959 return ConstantInt::getFalse(RHS->getContext()); 1960 } 1961 } 1962 1963 // Compare of cast, for example (zext X) != 0 -> X != 0 1964 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 1965 Instruction *LI = cast<CastInst>(LHS); 1966 Value *SrcOp = LI->getOperand(0); 1967 Type *SrcTy = SrcOp->getType(); 1968 Type *DstTy = LI->getType(); 1969 1970 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 1971 // if the integer type is the same size as the pointer type. 1972 if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) && 1973 Q.TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) { 1974 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 1975 // Transfer the cast to the constant. 1976 if (Value *V = SimplifyICmpInst(Pred, SrcOp, 1977 ConstantExpr::getIntToPtr(RHSC, SrcTy), 1978 Q, MaxRecurse-1)) 1979 return V; 1980 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 1981 if (RI->getOperand(0)->getType() == SrcTy) 1982 // Compare without the cast. 1983 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 1984 Q, MaxRecurse-1)) 1985 return V; 1986 } 1987 } 1988 1989 if (isa<ZExtInst>(LHS)) { 1990 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 1991 // same type. 1992 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 1993 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 1994 // Compare X and Y. Note that signed predicates become unsigned. 1995 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 1996 SrcOp, RI->getOperand(0), Q, 1997 MaxRecurse-1)) 1998 return V; 1999 } 2000 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 2001 // too. If not, then try to deduce the result of the comparison. 2002 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 2003 // Compute the constant that would happen if we truncated to SrcTy then 2004 // reextended to DstTy. 2005 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 2006 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy); 2007 2008 // If the re-extended constant didn't change then this is effectively 2009 // also a case of comparing two zero-extended values. 2010 if (RExt == CI && MaxRecurse) 2011 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 2012 SrcOp, Trunc, Q, MaxRecurse-1)) 2013 return V; 2014 2015 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 2016 // there. Use this to work out the result of the comparison. 2017 if (RExt != CI) { 2018 switch (Pred) { 2019 default: llvm_unreachable("Unknown ICmp predicate!"); 2020 // LHS <u RHS. 2021 case ICmpInst::ICMP_EQ: 2022 case ICmpInst::ICMP_UGT: 2023 case ICmpInst::ICMP_UGE: 2024 return ConstantInt::getFalse(CI->getContext()); 2025 2026 case ICmpInst::ICMP_NE: 2027 case ICmpInst::ICMP_ULT: 2028 case ICmpInst::ICMP_ULE: 2029 return ConstantInt::getTrue(CI->getContext()); 2030 2031 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 2032 // is non-negative then LHS <s RHS. 2033 case ICmpInst::ICMP_SGT: 2034 case ICmpInst::ICMP_SGE: 2035 return CI->getValue().isNegative() ? 2036 ConstantInt::getTrue(CI->getContext()) : 2037 ConstantInt::getFalse(CI->getContext()); 2038 2039 case ICmpInst::ICMP_SLT: 2040 case ICmpInst::ICMP_SLE: 2041 return CI->getValue().isNegative() ? 2042 ConstantInt::getFalse(CI->getContext()) : 2043 ConstantInt::getTrue(CI->getContext()); 2044 } 2045 } 2046 } 2047 } 2048 2049 if (isa<SExtInst>(LHS)) { 2050 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 2051 // same type. 2052 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 2053 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 2054 // Compare X and Y. Note that the predicate does not change. 2055 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 2056 Q, MaxRecurse-1)) 2057 return V; 2058 } 2059 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 2060 // too. If not, then try to deduce the result of the comparison. 2061 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 2062 // Compute the constant that would happen if we truncated to SrcTy then 2063 // reextended to DstTy. 2064 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 2065 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy); 2066 2067 // If the re-extended constant didn't change then this is effectively 2068 // also a case of comparing two sign-extended values. 2069 if (RExt == CI && MaxRecurse) 2070 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1)) 2071 return V; 2072 2073 // Otherwise the upper bits of LHS are all equal, while RHS has varying 2074 // bits there. Use this to work out the result of the comparison. 2075 if (RExt != CI) { 2076 switch (Pred) { 2077 default: llvm_unreachable("Unknown ICmp predicate!"); 2078 case ICmpInst::ICMP_EQ: 2079 return ConstantInt::getFalse(CI->getContext()); 2080 case ICmpInst::ICMP_NE: 2081 return ConstantInt::getTrue(CI->getContext()); 2082 2083 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 2084 // LHS >s RHS. 2085 case ICmpInst::ICMP_SGT: 2086 case ICmpInst::ICMP_SGE: 2087 return CI->getValue().isNegative() ? 2088 ConstantInt::getTrue(CI->getContext()) : 2089 ConstantInt::getFalse(CI->getContext()); 2090 case ICmpInst::ICMP_SLT: 2091 case ICmpInst::ICMP_SLE: 2092 return CI->getValue().isNegative() ? 2093 ConstantInt::getFalse(CI->getContext()) : 2094 ConstantInt::getTrue(CI->getContext()); 2095 2096 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 2097 // LHS >u RHS. 2098 case ICmpInst::ICMP_UGT: 2099 case ICmpInst::ICMP_UGE: 2100 // Comparison is true iff the LHS <s 0. 2101 if (MaxRecurse) 2102 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 2103 Constant::getNullValue(SrcTy), 2104 Q, MaxRecurse-1)) 2105 return V; 2106 break; 2107 case ICmpInst::ICMP_ULT: 2108 case ICmpInst::ICMP_ULE: 2109 // Comparison is true iff the LHS >=s 0. 2110 if (MaxRecurse) 2111 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 2112 Constant::getNullValue(SrcTy), 2113 Q, MaxRecurse-1)) 2114 return V; 2115 break; 2116 } 2117 } 2118 } 2119 } 2120 } 2121 2122 // Special logic for binary operators. 2123 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 2124 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 2125 if (MaxRecurse && (LBO || RBO)) { 2126 // Analyze the case when either LHS or RHS is an add instruction. 2127 Value *A = 0, *B = 0, *C = 0, *D = 0; 2128 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 2129 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 2130 if (LBO && LBO->getOpcode() == Instruction::Add) { 2131 A = LBO->getOperand(0); B = LBO->getOperand(1); 2132 NoLHSWrapProblem = ICmpInst::isEquality(Pred) || 2133 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) || 2134 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap()); 2135 } 2136 if (RBO && RBO->getOpcode() == Instruction::Add) { 2137 C = RBO->getOperand(0); D = RBO->getOperand(1); 2138 NoRHSWrapProblem = ICmpInst::isEquality(Pred) || 2139 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) || 2140 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap()); 2141 } 2142 2143 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 2144 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 2145 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A, 2146 Constant::getNullValue(RHS->getType()), 2147 Q, MaxRecurse-1)) 2148 return V; 2149 2150 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 2151 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 2152 if (Value *V = SimplifyICmpInst(Pred, 2153 Constant::getNullValue(LHS->getType()), 2154 C == LHS ? D : C, Q, MaxRecurse-1)) 2155 return V; 2156 2157 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 2158 if (A && C && (A == C || A == D || B == C || B == D) && 2159 NoLHSWrapProblem && NoRHSWrapProblem) { 2160 // Determine Y and Z in the form icmp (X+Y), (X+Z). 2161 Value *Y, *Z; 2162 if (A == C) { 2163 // C + B == C + D -> B == D 2164 Y = B; 2165 Z = D; 2166 } else if (A == D) { 2167 // D + B == C + D -> B == C 2168 Y = B; 2169 Z = C; 2170 } else if (B == C) { 2171 // A + C == C + D -> A == D 2172 Y = A; 2173 Z = D; 2174 } else { 2175 assert(B == D); 2176 // A + D == C + D -> A == C 2177 Y = A; 2178 Z = C; 2179 } 2180 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1)) 2181 return V; 2182 } 2183 } 2184 2185 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 2186 bool KnownNonNegative, KnownNegative; 2187 switch (Pred) { 2188 default: 2189 break; 2190 case ICmpInst::ICMP_SGT: 2191 case ICmpInst::ICMP_SGE: 2192 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD); 2193 if (!KnownNonNegative) 2194 break; 2195 // fall-through 2196 case ICmpInst::ICMP_EQ: 2197 case ICmpInst::ICMP_UGT: 2198 case ICmpInst::ICMP_UGE: 2199 return getFalse(ITy); 2200 case ICmpInst::ICMP_SLT: 2201 case ICmpInst::ICMP_SLE: 2202 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD); 2203 if (!KnownNonNegative) 2204 break; 2205 // fall-through 2206 case ICmpInst::ICMP_NE: 2207 case ICmpInst::ICMP_ULT: 2208 case ICmpInst::ICMP_ULE: 2209 return getTrue(ITy); 2210 } 2211 } 2212 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) { 2213 bool KnownNonNegative, KnownNegative; 2214 switch (Pred) { 2215 default: 2216 break; 2217 case ICmpInst::ICMP_SGT: 2218 case ICmpInst::ICMP_SGE: 2219 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD); 2220 if (!KnownNonNegative) 2221 break; 2222 // fall-through 2223 case ICmpInst::ICMP_NE: 2224 case ICmpInst::ICMP_UGT: 2225 case ICmpInst::ICMP_UGE: 2226 return getTrue(ITy); 2227 case ICmpInst::ICMP_SLT: 2228 case ICmpInst::ICMP_SLE: 2229 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD); 2230 if (!KnownNonNegative) 2231 break; 2232 // fall-through 2233 case ICmpInst::ICMP_EQ: 2234 case ICmpInst::ICMP_ULT: 2235 case ICmpInst::ICMP_ULE: 2236 return getFalse(ITy); 2237 } 2238 } 2239 2240 // x udiv y <=u x. 2241 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) { 2242 // icmp pred (X /u Y), X 2243 if (Pred == ICmpInst::ICMP_UGT) 2244 return getFalse(ITy); 2245 if (Pred == ICmpInst::ICMP_ULE) 2246 return getTrue(ITy); 2247 } 2248 2249 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() && 2250 LBO->getOperand(1) == RBO->getOperand(1)) { 2251 switch (LBO->getOpcode()) { 2252 default: break; 2253 case Instruction::UDiv: 2254 case Instruction::LShr: 2255 if (ICmpInst::isSigned(Pred)) 2256 break; 2257 // fall-through 2258 case Instruction::SDiv: 2259 case Instruction::AShr: 2260 if (!LBO->isExact() || !RBO->isExact()) 2261 break; 2262 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 2263 RBO->getOperand(0), Q, MaxRecurse-1)) 2264 return V; 2265 break; 2266 case Instruction::Shl: { 2267 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap(); 2268 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap(); 2269 if (!NUW && !NSW) 2270 break; 2271 if (!NSW && ICmpInst::isSigned(Pred)) 2272 break; 2273 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 2274 RBO->getOperand(0), Q, MaxRecurse-1)) 2275 return V; 2276 break; 2277 } 2278 } 2279 } 2280 2281 // Simplify comparisons involving max/min. 2282 Value *A, *B; 2283 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 2284 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 2285 2286 // Signed variants on "max(a,b)>=a -> true". 2287 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 2288 if (A != RHS) std::swap(A, B); // smax(A, B) pred A. 2289 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 2290 // We analyze this as smax(A, B) pred A. 2291 P = Pred; 2292 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 2293 (A == LHS || B == LHS)) { 2294 if (A != LHS) std::swap(A, B); // A pred smax(A, B). 2295 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 2296 // We analyze this as smax(A, B) swapped-pred A. 2297 P = CmpInst::getSwappedPredicate(Pred); 2298 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 2299 (A == RHS || B == RHS)) { 2300 if (A != RHS) std::swap(A, B); // smin(A, B) pred A. 2301 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 2302 // We analyze this as smax(-A, -B) swapped-pred -A. 2303 // Note that we do not need to actually form -A or -B thanks to EqP. 2304 P = CmpInst::getSwappedPredicate(Pred); 2305 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 2306 (A == LHS || B == LHS)) { 2307 if (A != LHS) std::swap(A, B); // A pred smin(A, B). 2308 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 2309 // We analyze this as smax(-A, -B) pred -A. 2310 // Note that we do not need to actually form -A or -B thanks to EqP. 2311 P = Pred; 2312 } 2313 if (P != CmpInst::BAD_ICMP_PREDICATE) { 2314 // Cases correspond to "max(A, B) p A". 2315 switch (P) { 2316 default: 2317 break; 2318 case CmpInst::ICMP_EQ: 2319 case CmpInst::ICMP_SLE: 2320 // Equivalent to "A EqP B". This may be the same as the condition tested 2321 // in the max/min; if so, we can just return that. 2322 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 2323 return V; 2324 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 2325 return V; 2326 // Otherwise, see if "A EqP B" simplifies. 2327 if (MaxRecurse) 2328 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1)) 2329 return V; 2330 break; 2331 case CmpInst::ICMP_NE: 2332 case CmpInst::ICMP_SGT: { 2333 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 2334 // Equivalent to "A InvEqP B". This may be the same as the condition 2335 // tested in the max/min; if so, we can just return that. 2336 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 2337 return V; 2338 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 2339 return V; 2340 // Otherwise, see if "A InvEqP B" simplifies. 2341 if (MaxRecurse) 2342 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1)) 2343 return V; 2344 break; 2345 } 2346 case CmpInst::ICMP_SGE: 2347 // Always true. 2348 return getTrue(ITy); 2349 case CmpInst::ICMP_SLT: 2350 // Always false. 2351 return getFalse(ITy); 2352 } 2353 } 2354 2355 // Unsigned variants on "max(a,b)>=a -> true". 2356 P = CmpInst::BAD_ICMP_PREDICATE; 2357 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 2358 if (A != RHS) std::swap(A, B); // umax(A, B) pred A. 2359 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 2360 // We analyze this as umax(A, B) pred A. 2361 P = Pred; 2362 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 2363 (A == LHS || B == LHS)) { 2364 if (A != LHS) std::swap(A, B); // A pred umax(A, B). 2365 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 2366 // We analyze this as umax(A, B) swapped-pred A. 2367 P = CmpInst::getSwappedPredicate(Pred); 2368 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 2369 (A == RHS || B == RHS)) { 2370 if (A != RHS) std::swap(A, B); // umin(A, B) pred A. 2371 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 2372 // We analyze this as umax(-A, -B) swapped-pred -A. 2373 // Note that we do not need to actually form -A or -B thanks to EqP. 2374 P = CmpInst::getSwappedPredicate(Pred); 2375 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 2376 (A == LHS || B == LHS)) { 2377 if (A != LHS) std::swap(A, B); // A pred umin(A, B). 2378 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 2379 // We analyze this as umax(-A, -B) pred -A. 2380 // Note that we do not need to actually form -A or -B thanks to EqP. 2381 P = Pred; 2382 } 2383 if (P != CmpInst::BAD_ICMP_PREDICATE) { 2384 // Cases correspond to "max(A, B) p A". 2385 switch (P) { 2386 default: 2387 break; 2388 case CmpInst::ICMP_EQ: 2389 case CmpInst::ICMP_ULE: 2390 // Equivalent to "A EqP B". This may be the same as the condition tested 2391 // in the max/min; if so, we can just return that. 2392 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 2393 return V; 2394 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 2395 return V; 2396 // Otherwise, see if "A EqP B" simplifies. 2397 if (MaxRecurse) 2398 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1)) 2399 return V; 2400 break; 2401 case CmpInst::ICMP_NE: 2402 case CmpInst::ICMP_UGT: { 2403 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 2404 // Equivalent to "A InvEqP B". This may be the same as the condition 2405 // tested in the max/min; if so, we can just return that. 2406 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 2407 return V; 2408 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 2409 return V; 2410 // Otherwise, see if "A InvEqP B" simplifies. 2411 if (MaxRecurse) 2412 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1)) 2413 return V; 2414 break; 2415 } 2416 case CmpInst::ICMP_UGE: 2417 // Always true. 2418 return getTrue(ITy); 2419 case CmpInst::ICMP_ULT: 2420 // Always false. 2421 return getFalse(ITy); 2422 } 2423 } 2424 2425 // Variants on "max(x,y) >= min(x,z)". 2426 Value *C, *D; 2427 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 2428 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 2429 (A == C || A == D || B == C || B == D)) { 2430 // max(x, ?) pred min(x, ?). 2431 if (Pred == CmpInst::ICMP_SGE) 2432 // Always true. 2433 return getTrue(ITy); 2434 if (Pred == CmpInst::ICMP_SLT) 2435 // Always false. 2436 return getFalse(ITy); 2437 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 2438 match(RHS, m_SMax(m_Value(C), m_Value(D))) && 2439 (A == C || A == D || B == C || B == D)) { 2440 // min(x, ?) pred max(x, ?). 2441 if (Pred == CmpInst::ICMP_SLE) 2442 // Always true. 2443 return getTrue(ITy); 2444 if (Pred == CmpInst::ICMP_SGT) 2445 // Always false. 2446 return getFalse(ITy); 2447 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 2448 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 2449 (A == C || A == D || B == C || B == D)) { 2450 // max(x, ?) pred min(x, ?). 2451 if (Pred == CmpInst::ICMP_UGE) 2452 // Always true. 2453 return getTrue(ITy); 2454 if (Pred == CmpInst::ICMP_ULT) 2455 // Always false. 2456 return getFalse(ITy); 2457 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 2458 match(RHS, m_UMax(m_Value(C), m_Value(D))) && 2459 (A == C || A == D || B == C || B == D)) { 2460 // min(x, ?) pred max(x, ?). 2461 if (Pred == CmpInst::ICMP_ULE) 2462 // Always true. 2463 return getTrue(ITy); 2464 if (Pred == CmpInst::ICMP_UGT) 2465 // Always false. 2466 return getFalse(ITy); 2467 } 2468 2469 // Simplify comparisons of related pointers using a powerful, recursive 2470 // GEP-walk when we have target data available.. 2471 if (Q.TD && LHS->getType()->isPointerTy() && RHS->getType()->isPointerTy()) 2472 if (Constant *C = computePointerICmp(*Q.TD, Pred, LHS, RHS)) 2473 return C; 2474 2475 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) { 2476 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) { 2477 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() && 2478 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() && 2479 (ICmpInst::isEquality(Pred) || 2480 (GLHS->isInBounds() && GRHS->isInBounds() && 2481 Pred == ICmpInst::getSignedPredicate(Pred)))) { 2482 // The bases are equal and the indices are constant. Build a constant 2483 // expression GEP with the same indices and a null base pointer to see 2484 // what constant folding can make out of it. 2485 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType()); 2486 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end()); 2487 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS); 2488 2489 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end()); 2490 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS); 2491 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS); 2492 } 2493 } 2494 } 2495 2496 // If the comparison is with the result of a select instruction, check whether 2497 // comparing with either branch of the select always yields the same value. 2498 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2499 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 2500 return V; 2501 2502 // If the comparison is with the result of a phi instruction, check whether 2503 // doing the compare with each incoming phi value yields a common result. 2504 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2505 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 2506 return V; 2507 2508 return 0; 2509} 2510 2511Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2512 const DataLayout *TD, 2513 const TargetLibraryInfo *TLI, 2514 const DominatorTree *DT) { 2515 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), 2516 RecursionLimit); 2517} 2518 2519/// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can 2520/// fold the result. If not, this returns null. 2521static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2522 const Query &Q, unsigned MaxRecurse) { 2523 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 2524 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 2525 2526 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 2527 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 2528 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI); 2529 2530 // If we have a constant, make sure it is on the RHS. 2531 std::swap(LHS, RHS); 2532 Pred = CmpInst::getSwappedPredicate(Pred); 2533 } 2534 2535 // Fold trivial predicates. 2536 if (Pred == FCmpInst::FCMP_FALSE) 2537 return ConstantInt::get(GetCompareTy(LHS), 0); 2538 if (Pred == FCmpInst::FCMP_TRUE) 2539 return ConstantInt::get(GetCompareTy(LHS), 1); 2540 2541 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef 2542 return UndefValue::get(GetCompareTy(LHS)); 2543 2544 // fcmp x,x -> true/false. Not all compares are foldable. 2545 if (LHS == RHS) { 2546 if (CmpInst::isTrueWhenEqual(Pred)) 2547 return ConstantInt::get(GetCompareTy(LHS), 1); 2548 if (CmpInst::isFalseWhenEqual(Pred)) 2549 return ConstantInt::get(GetCompareTy(LHS), 0); 2550 } 2551 2552 // Handle fcmp with constant RHS 2553 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 2554 // If the constant is a nan, see if we can fold the comparison based on it. 2555 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { 2556 if (CFP->getValueAPF().isNaN()) { 2557 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo" 2558 return ConstantInt::getFalse(CFP->getContext()); 2559 assert(FCmpInst::isUnordered(Pred) && 2560 "Comparison must be either ordered or unordered!"); 2561 // True if unordered. 2562 return ConstantInt::getTrue(CFP->getContext()); 2563 } 2564 // Check whether the constant is an infinity. 2565 if (CFP->getValueAPF().isInfinity()) { 2566 if (CFP->getValueAPF().isNegative()) { 2567 switch (Pred) { 2568 case FCmpInst::FCMP_OLT: 2569 // No value is ordered and less than negative infinity. 2570 return ConstantInt::getFalse(CFP->getContext()); 2571 case FCmpInst::FCMP_UGE: 2572 // All values are unordered with or at least negative infinity. 2573 return ConstantInt::getTrue(CFP->getContext()); 2574 default: 2575 break; 2576 } 2577 } else { 2578 switch (Pred) { 2579 case FCmpInst::FCMP_OGT: 2580 // No value is ordered and greater than infinity. 2581 return ConstantInt::getFalse(CFP->getContext()); 2582 case FCmpInst::FCMP_ULE: 2583 // All values are unordered with and at most infinity. 2584 return ConstantInt::getTrue(CFP->getContext()); 2585 default: 2586 break; 2587 } 2588 } 2589 } 2590 } 2591 } 2592 2593 // If the comparison is with the result of a select instruction, check whether 2594 // comparing with either branch of the select always yields the same value. 2595 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2596 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 2597 return V; 2598 2599 // If the comparison is with the result of a phi instruction, check whether 2600 // doing the compare with each incoming phi value yields a common result. 2601 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2602 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 2603 return V; 2604 2605 return 0; 2606} 2607 2608Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2609 const DataLayout *TD, 2610 const TargetLibraryInfo *TLI, 2611 const DominatorTree *DT) { 2612 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), 2613 RecursionLimit); 2614} 2615 2616/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold 2617/// the result. If not, this returns null. 2618static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal, 2619 Value *FalseVal, const Query &Q, 2620 unsigned MaxRecurse) { 2621 // select true, X, Y -> X 2622 // select false, X, Y -> Y 2623 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal)) 2624 return CB->getZExtValue() ? TrueVal : FalseVal; 2625 2626 // select C, X, X -> X 2627 if (TrueVal == FalseVal) 2628 return TrueVal; 2629 2630 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y 2631 if (isa<Constant>(TrueVal)) 2632 return TrueVal; 2633 return FalseVal; 2634 } 2635 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X 2636 return FalseVal; 2637 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X 2638 return TrueVal; 2639 2640 return 0; 2641} 2642 2643Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 2644 const DataLayout *TD, 2645 const TargetLibraryInfo *TLI, 2646 const DominatorTree *DT) { 2647 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT), 2648 RecursionLimit); 2649} 2650 2651/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can 2652/// fold the result. If not, this returns null. 2653static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) { 2654 // The type of the GEP pointer operand. 2655 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType()); 2656 // The GEP pointer operand is not a pointer, it's a vector of pointers. 2657 if (!PtrTy) 2658 return 0; 2659 2660 // getelementptr P -> P. 2661 if (Ops.size() == 1) 2662 return Ops[0]; 2663 2664 if (isa<UndefValue>(Ops[0])) { 2665 // Compute the (pointer) type returned by the GEP instruction. 2666 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1)); 2667 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace()); 2668 return UndefValue::get(GEPTy); 2669 } 2670 2671 if (Ops.size() == 2) { 2672 // getelementptr P, 0 -> P. 2673 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1])) 2674 if (C->isZero()) 2675 return Ops[0]; 2676 // getelementptr P, N -> P if P points to a type of zero size. 2677 if (Q.TD) { 2678 Type *Ty = PtrTy->getElementType(); 2679 if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0) 2680 return Ops[0]; 2681 } 2682 } 2683 2684 // Check to see if this is constant foldable. 2685 for (unsigned i = 0, e = Ops.size(); i != e; ++i) 2686 if (!isa<Constant>(Ops[i])) 2687 return 0; 2688 2689 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1)); 2690} 2691 2692Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const DataLayout *TD, 2693 const TargetLibraryInfo *TLI, 2694 const DominatorTree *DT) { 2695 return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit); 2696} 2697 2698/// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we 2699/// can fold the result. If not, this returns null. 2700static Value *SimplifyInsertValueInst(Value *Agg, Value *Val, 2701 ArrayRef<unsigned> Idxs, const Query &Q, 2702 unsigned) { 2703 if (Constant *CAgg = dyn_cast<Constant>(Agg)) 2704 if (Constant *CVal = dyn_cast<Constant>(Val)) 2705 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); 2706 2707 // insertvalue x, undef, n -> x 2708 if (match(Val, m_Undef())) 2709 return Agg; 2710 2711 // insertvalue x, (extractvalue y, n), n 2712 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) 2713 if (EV->getAggregateOperand()->getType() == Agg->getType() && 2714 EV->getIndices() == Idxs) { 2715 // insertvalue undef, (extractvalue y, n), n -> y 2716 if (match(Agg, m_Undef())) 2717 return EV->getAggregateOperand(); 2718 2719 // insertvalue y, (extractvalue y, n), n -> y 2720 if (Agg == EV->getAggregateOperand()) 2721 return Agg; 2722 } 2723 2724 return 0; 2725} 2726 2727Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val, 2728 ArrayRef<unsigned> Idxs, 2729 const DataLayout *TD, 2730 const TargetLibraryInfo *TLI, 2731 const DominatorTree *DT) { 2732 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT), 2733 RecursionLimit); 2734} 2735 2736/// SimplifyPHINode - See if we can fold the given phi. If not, returns null. 2737static Value *SimplifyPHINode(PHINode *PN, const Query &Q) { 2738 // If all of the PHI's incoming values are the same then replace the PHI node 2739 // with the common value. 2740 Value *CommonValue = 0; 2741 bool HasUndefInput = false; 2742 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 2743 Value *Incoming = PN->getIncomingValue(i); 2744 // If the incoming value is the phi node itself, it can safely be skipped. 2745 if (Incoming == PN) continue; 2746 if (isa<UndefValue>(Incoming)) { 2747 // Remember that we saw an undef value, but otherwise ignore them. 2748 HasUndefInput = true; 2749 continue; 2750 } 2751 if (CommonValue && Incoming != CommonValue) 2752 return 0; // Not the same, bail out. 2753 CommonValue = Incoming; 2754 } 2755 2756 // If CommonValue is null then all of the incoming values were either undef or 2757 // equal to the phi node itself. 2758 if (!CommonValue) 2759 return UndefValue::get(PN->getType()); 2760 2761 // If we have a PHI node like phi(X, undef, X), where X is defined by some 2762 // instruction, we cannot return X as the result of the PHI node unless it 2763 // dominates the PHI block. 2764 if (HasUndefInput) 2765 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : 0; 2766 2767 return CommonValue; 2768} 2769 2770static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) { 2771 if (Constant *C = dyn_cast<Constant>(Op)) 2772 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.TD, Q.TLI); 2773 2774 return 0; 2775} 2776 2777Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout *TD, 2778 const TargetLibraryInfo *TLI, 2779 const DominatorTree *DT) { 2780 return ::SimplifyTruncInst(Op, Ty, Query (TD, TLI, DT), RecursionLimit); 2781} 2782 2783//=== Helper functions for higher up the class hierarchy. 2784 2785/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can 2786/// fold the result. If not, this returns null. 2787static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 2788 const Query &Q, unsigned MaxRecurse) { 2789 switch (Opcode) { 2790 case Instruction::Add: 2791 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2792 Q, MaxRecurse); 2793 case Instruction::FAdd: 2794 return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 2795 2796 case Instruction::Sub: 2797 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2798 Q, MaxRecurse); 2799 case Instruction::FSub: 2800 return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 2801 2802 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse); 2803 case Instruction::FMul: 2804 return SimplifyFMulInst (LHS, RHS, FastMathFlags(), Q, MaxRecurse); 2805 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse); 2806 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse); 2807 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse); 2808 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse); 2809 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse); 2810 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse); 2811 case Instruction::Shl: 2812 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2813 Q, MaxRecurse); 2814 case Instruction::LShr: 2815 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse); 2816 case Instruction::AShr: 2817 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse); 2818 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse); 2819 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse); 2820 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse); 2821 default: 2822 if (Constant *CLHS = dyn_cast<Constant>(LHS)) 2823 if (Constant *CRHS = dyn_cast<Constant>(RHS)) { 2824 Constant *COps[] = {CLHS, CRHS}; 2825 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.TD, 2826 Q.TLI); 2827 } 2828 2829 // If the operation is associative, try some generic simplifications. 2830 if (Instruction::isAssociative(Opcode)) 2831 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse)) 2832 return V; 2833 2834 // If the operation is with the result of a select instruction check whether 2835 // operating on either branch of the select always yields the same value. 2836 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2837 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse)) 2838 return V; 2839 2840 // If the operation is with the result of a phi instruction, check whether 2841 // operating on all incoming values of the phi always yields the same value. 2842 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2843 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse)) 2844 return V; 2845 2846 return 0; 2847 } 2848} 2849 2850Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 2851 const DataLayout *TD, const TargetLibraryInfo *TLI, 2852 const DominatorTree *DT) { 2853 return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, DT), RecursionLimit); 2854} 2855 2856/// SimplifyCmpInst - Given operands for a CmpInst, see if we can 2857/// fold the result. 2858static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2859 const Query &Q, unsigned MaxRecurse) { 2860 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 2861 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 2862 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 2863} 2864 2865Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2866 const DataLayout *TD, const TargetLibraryInfo *TLI, 2867 const DominatorTree *DT) { 2868 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), 2869 RecursionLimit); 2870} 2871 2872template <typename IterTy> 2873static Value *SimplifyCall(Value *F, IterTy ArgBegin, IterTy ArgEnd, 2874 const Query &Q, unsigned MaxRecurse) { 2875 Type *Ty = F->getType(); 2876 if (PointerType *PTy = dyn_cast<PointerType>(Ty)) 2877 Ty = PTy->getElementType(); 2878 FunctionType *FTy = cast<FunctionType>(Ty); 2879 2880 // call undef -> undef 2881 if (isa<UndefValue>(F)) 2882 return UndefValue::get(FTy->getReturnType()); 2883 2884 return 0; 2885} 2886 2887Value *llvm::SimplifyCall(Value *F, User::op_iterator ArgBegin, 2888 User::op_iterator ArgEnd, const DataLayout *TD, 2889 const TargetLibraryInfo *TLI, 2890 const DominatorTree *DT) { 2891 return ::SimplifyCall(F, ArgBegin, ArgEnd, Query(TD, TLI, DT), 2892 RecursionLimit); 2893} 2894 2895Value *llvm::SimplifyCall(Value *F, ArrayRef<Value *> Args, 2896 const DataLayout *TD, const TargetLibraryInfo *TLI, 2897 const DominatorTree *DT) { 2898 return ::SimplifyCall(F, Args.begin(), Args.end(), Query(TD, TLI, DT), 2899 RecursionLimit); 2900} 2901 2902/// SimplifyInstruction - See if we can compute a simplified version of this 2903/// instruction. If not, this returns null. 2904Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *TD, 2905 const TargetLibraryInfo *TLI, 2906 const DominatorTree *DT) { 2907 Value *Result; 2908 2909 switch (I->getOpcode()) { 2910 default: 2911 Result = ConstantFoldInstruction(I, TD, TLI); 2912 break; 2913 case Instruction::FAdd: 2914 Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1), 2915 I->getFastMathFlags(), TD, TLI, DT); 2916 break; 2917 case Instruction::Add: 2918 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1), 2919 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2920 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2921 TD, TLI, DT); 2922 break; 2923 case Instruction::FSub: 2924 Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1), 2925 I->getFastMathFlags(), TD, TLI, DT); 2926 break; 2927 case Instruction::Sub: 2928 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1), 2929 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2930 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2931 TD, TLI, DT); 2932 break; 2933 case Instruction::FMul: 2934 Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1), 2935 I->getFastMathFlags(), TD, TLI, DT); 2936 break; 2937 case Instruction::Mul: 2938 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2939 break; 2940 case Instruction::SDiv: 2941 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2942 break; 2943 case Instruction::UDiv: 2944 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2945 break; 2946 case Instruction::FDiv: 2947 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2948 break; 2949 case Instruction::SRem: 2950 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2951 break; 2952 case Instruction::URem: 2953 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2954 break; 2955 case Instruction::FRem: 2956 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2957 break; 2958 case Instruction::Shl: 2959 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), 2960 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2961 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2962 TD, TLI, DT); 2963 break; 2964 case Instruction::LShr: 2965 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), 2966 cast<BinaryOperator>(I)->isExact(), 2967 TD, TLI, DT); 2968 break; 2969 case Instruction::AShr: 2970 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), 2971 cast<BinaryOperator>(I)->isExact(), 2972 TD, TLI, DT); 2973 break; 2974 case Instruction::And: 2975 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2976 break; 2977 case Instruction::Or: 2978 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2979 break; 2980 case Instruction::Xor: 2981 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2982 break; 2983 case Instruction::ICmp: 2984 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), 2985 I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2986 break; 2987 case Instruction::FCmp: 2988 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), 2989 I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2990 break; 2991 case Instruction::Select: 2992 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), 2993 I->getOperand(2), TD, TLI, DT); 2994 break; 2995 case Instruction::GetElementPtr: { 2996 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end()); 2997 Result = SimplifyGEPInst(Ops, TD, TLI, DT); 2998 break; 2999 } 3000 case Instruction::InsertValue: { 3001 InsertValueInst *IV = cast<InsertValueInst>(I); 3002 Result = SimplifyInsertValueInst(IV->getAggregateOperand(), 3003 IV->getInsertedValueOperand(), 3004 IV->getIndices(), TD, TLI, DT); 3005 break; 3006 } 3007 case Instruction::PHI: 3008 Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT)); 3009 break; 3010 case Instruction::Call: { 3011 CallSite CS(cast<CallInst>(I)); 3012 Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(), 3013 TD, TLI, DT); 3014 break; 3015 } 3016 case Instruction::Trunc: 3017 Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, DT); 3018 break; 3019 } 3020 3021 /// If called on unreachable code, the above logic may report that the 3022 /// instruction simplified to itself. Make life easier for users by 3023 /// detecting that case here, returning a safe value instead. 3024 return Result == I ? UndefValue::get(I->getType()) : Result; 3025} 3026 3027/// \brief Implementation of recursive simplification through an instructions 3028/// uses. 3029/// 3030/// This is the common implementation of the recursive simplification routines. 3031/// If we have a pre-simplified value in 'SimpleV', that is forcibly used to 3032/// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of 3033/// instructions to process and attempt to simplify it using 3034/// InstructionSimplify. 3035/// 3036/// This routine returns 'true' only when *it* simplifies something. The passed 3037/// in simplified value does not count toward this. 3038static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV, 3039 const DataLayout *TD, 3040 const TargetLibraryInfo *TLI, 3041 const DominatorTree *DT) { 3042 bool Simplified = false; 3043 SmallSetVector<Instruction *, 8> Worklist; 3044 3045 // If we have an explicit value to collapse to, do that round of the 3046 // simplification loop by hand initially. 3047 if (SimpleV) { 3048 for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE; 3049 ++UI) 3050 if (*UI != I) 3051 Worklist.insert(cast<Instruction>(*UI)); 3052 3053 // Replace the instruction with its simplified value. 3054 I->replaceAllUsesWith(SimpleV); 3055 3056 // Gracefully handle edge cases where the instruction is not wired into any 3057 // parent block. 3058 if (I->getParent()) 3059 I->eraseFromParent(); 3060 } else { 3061 Worklist.insert(I); 3062 } 3063 3064 // Note that we must test the size on each iteration, the worklist can grow. 3065 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { 3066 I = Worklist[Idx]; 3067 3068 // See if this instruction simplifies. 3069 SimpleV = SimplifyInstruction(I, TD, TLI, DT); 3070 if (!SimpleV) 3071 continue; 3072 3073 Simplified = true; 3074 3075 // Stash away all the uses of the old instruction so we can check them for 3076 // recursive simplifications after a RAUW. This is cheaper than checking all 3077 // uses of To on the recursive step in most cases. 3078 for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE; 3079 ++UI) 3080 Worklist.insert(cast<Instruction>(*UI)); 3081 3082 // Replace the instruction with its simplified value. 3083 I->replaceAllUsesWith(SimpleV); 3084 3085 // Gracefully handle edge cases where the instruction is not wired into any 3086 // parent block. 3087 if (I->getParent()) 3088 I->eraseFromParent(); 3089 } 3090 return Simplified; 3091} 3092 3093bool llvm::recursivelySimplifyInstruction(Instruction *I, 3094 const DataLayout *TD, 3095 const TargetLibraryInfo *TLI, 3096 const DominatorTree *DT) { 3097 return replaceAndRecursivelySimplifyImpl(I, 0, TD, TLI, DT); 3098} 3099 3100bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV, 3101 const DataLayout *TD, 3102 const TargetLibraryInfo *TLI, 3103 const DominatorTree *DT) { 3104 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!"); 3105 assert(SimpleV && "Must provide a simplified value."); 3106 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TD, TLI, DT); 3107} 3108