InstructionSimplify.cpp revision ff739c1575df58f3926c2f3b6e00a6c45f773523
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/GlobalAlias.h" 22#include "llvm/Operator.h" 23#include "llvm/ADT/Statistic.h" 24#include "llvm/Analysis/InstructionSimplify.h" 25#include "llvm/Analysis/AliasAnalysis.h" 26#include "llvm/Analysis/ConstantFolding.h" 27#include "llvm/Analysis/Dominators.h" 28#include "llvm/Analysis/ValueTracking.h" 29#include "llvm/Support/ConstantRange.h" 30#include "llvm/Support/GetElementPtrTypeIterator.h" 31#include "llvm/Support/PatternMatch.h" 32#include "llvm/Support/ValueHandle.h" 33#include "llvm/Target/TargetData.h" 34using namespace llvm; 35using namespace llvm::PatternMatch; 36 37enum { RecursionLimit = 3 }; 38 39STATISTIC(NumExpand, "Number of expansions"); 40STATISTIC(NumFactor , "Number of factorizations"); 41STATISTIC(NumReassoc, "Number of reassociations"); 42 43struct Query { 44 const TargetData *TD; 45 const TargetLibraryInfo *TLI; 46 const DominatorTree *DT; 47 48 Query(const TargetData *td, const TargetLibraryInfo *tli, 49 const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {}; 50}; 51 52static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned); 53static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &, 54 unsigned); 55static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &, 56 unsigned); 57static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned); 58static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned); 59static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned); 60 61/// getFalse - For a boolean type, or a vector of boolean type, return false, or 62/// a vector with every element false, as appropriate for the type. 63static Constant *getFalse(Type *Ty) { 64 assert(Ty->getScalarType()->isIntegerTy(1) && 65 "Expected i1 type or a vector of i1!"); 66 return Constant::getNullValue(Ty); 67} 68 69/// getTrue - For a boolean type, or a vector of boolean type, return true, or 70/// a vector with every element true, as appropriate for the type. 71static Constant *getTrue(Type *Ty) { 72 assert(Ty->getScalarType()->isIntegerTy(1) && 73 "Expected i1 type or a vector of i1!"); 74 return Constant::getAllOnesValue(Ty); 75} 76 77/// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? 78static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, 79 Value *RHS) { 80 CmpInst *Cmp = dyn_cast<CmpInst>(V); 81 if (!Cmp) 82 return false; 83 CmpInst::Predicate CPred = Cmp->getPredicate(); 84 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); 85 if (CPred == Pred && CLHS == LHS && CRHS == RHS) 86 return true; 87 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && 88 CRHS == LHS; 89} 90 91/// ValueDominatesPHI - Does the given value dominate the specified phi node? 92static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 93 Instruction *I = dyn_cast<Instruction>(V); 94 if (!I) 95 // Arguments and constants dominate all instructions. 96 return true; 97 98 // If we are processing instructions (and/or basic blocks) that have not been 99 // fully added to a function, the parent nodes may still be null. Simply 100 // return the conservative answer in these cases. 101 if (!I->getParent() || !P->getParent() || !I->getParent()->getParent()) 102 return false; 103 104 // If we have a DominatorTree then do a precise test. 105 if (DT) { 106 if (!DT->isReachableFromEntry(P->getParent())) 107 return true; 108 if (!DT->isReachableFromEntry(I->getParent())) 109 return false; 110 return DT->dominates(I, P); 111 } 112 113 // Otherwise, if the instruction is in the entry block, and is not an invoke, 114 // then it obviously dominates all phi nodes. 115 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() && 116 !isa<InvokeInst>(I)) 117 return true; 118 119 return false; 120} 121 122/// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning 123/// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is 124/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS. 125/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)". 126/// Returns the simplified value, or null if no simplification was performed. 127static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS, 128 unsigned OpcToExpand, const Query &Q, 129 unsigned MaxRecurse) { 130 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand; 131 // Recursion is always used, so bail out at once if we already hit the limit. 132 if (!MaxRecurse--) 133 return 0; 134 135 // Check whether the expression has the form "(A op' B) op C". 136 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS)) 137 if (Op0->getOpcode() == OpcodeToExpand) { 138 // It does! Try turning it into "(A op C) op' (B op C)". 139 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS; 140 // Do "A op C" and "B op C" both simplify? 141 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) 142 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 143 // They do! Return "L op' R" if it simplifies or is already available. 144 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS. 145 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand) 146 && L == B && R == A)) { 147 ++NumExpand; 148 return LHS; 149 } 150 // Otherwise return "L op' R" if it simplifies. 151 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { 152 ++NumExpand; 153 return V; 154 } 155 } 156 } 157 158 // Check whether the expression has the form "A op (B op' C)". 159 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS)) 160 if (Op1->getOpcode() == OpcodeToExpand) { 161 // It does! Try turning it into "(A op B) op' (A op C)". 162 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1); 163 // Do "A op B" and "A op C" both simplify? 164 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) 165 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) { 166 // They do! Return "L op' R" if it simplifies or is already available. 167 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS. 168 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand) 169 && L == C && R == B)) { 170 ++NumExpand; 171 return RHS; 172 } 173 // Otherwise return "L op' R" if it simplifies. 174 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { 175 ++NumExpand; 176 return V; 177 } 178 } 179 } 180 181 return 0; 182} 183 184/// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term 185/// using the operation OpCodeToExtract. For example, when Opcode is Add and 186/// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)". 187/// Returns the simplified value, or null if no simplification was performed. 188static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS, 189 unsigned OpcToExtract, const Query &Q, 190 unsigned MaxRecurse) { 191 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract; 192 // Recursion is always used, so bail out at once if we already hit the limit. 193 if (!MaxRecurse--) 194 return 0; 195 196 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 197 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 198 199 if (!Op0 || Op0->getOpcode() != OpcodeToExtract || 200 !Op1 || Op1->getOpcode() != OpcodeToExtract) 201 return 0; 202 203 // The expression has the form "(A op' B) op (C op' D)". 204 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1); 205 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1); 206 207 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)". 208 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the 209 // commutative case, "(A op' B) op (C op' A)"? 210 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) { 211 Value *DD = A == C ? D : C; 212 // Form "A op' (B op DD)" if it simplifies completely. 213 // Does "B op DD" simplify? 214 if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) { 215 // It does! Return "A op' V" if it simplifies or is already available. 216 // If V equals B then "A op' V" is just the LHS. If V equals DD then 217 // "A op' V" is just the RHS. 218 if (V == B || V == DD) { 219 ++NumFactor; 220 return V == B ? LHS : RHS; 221 } 222 // Otherwise return "A op' V" if it simplifies. 223 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) { 224 ++NumFactor; 225 return W; 226 } 227 } 228 } 229 230 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)". 231 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the 232 // commutative case, "(A op' B) op (B op' D)"? 233 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) { 234 Value *CC = B == D ? C : D; 235 // Form "(A op CC) op' B" if it simplifies completely.. 236 // Does "A op CC" simplify? 237 if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) { 238 // It does! Return "V op' B" if it simplifies or is already available. 239 // If V equals A then "V op' B" is just the LHS. If V equals CC then 240 // "V op' B" is just the RHS. 241 if (V == A || V == CC) { 242 ++NumFactor; 243 return V == A ? LHS : RHS; 244 } 245 // Otherwise return "V op' B" if it simplifies. 246 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) { 247 ++NumFactor; 248 return W; 249 } 250 } 251 } 252 253 return 0; 254} 255 256/// SimplifyAssociativeBinOp - Generic simplifications for associative binary 257/// operations. Returns the simpler value, or null if none was found. 258static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS, 259 const Query &Q, unsigned MaxRecurse) { 260 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc; 261 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 262 263 // Recursion is always used, so bail out at once if we already hit the limit. 264 if (!MaxRecurse--) 265 return 0; 266 267 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 268 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 269 270 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 271 if (Op0 && Op0->getOpcode() == Opcode) { 272 Value *A = Op0->getOperand(0); 273 Value *B = Op0->getOperand(1); 274 Value *C = RHS; 275 276 // Does "B op C" simplify? 277 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 278 // It does! Return "A op V" if it simplifies or is already available. 279 // If V equals B then "A op V" is just the LHS. 280 if (V == B) return LHS; 281 // Otherwise return "A op V" if it simplifies. 282 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { 283 ++NumReassoc; 284 return W; 285 } 286 } 287 } 288 289 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 290 if (Op1 && Op1->getOpcode() == Opcode) { 291 Value *A = LHS; 292 Value *B = Op1->getOperand(0); 293 Value *C = Op1->getOperand(1); 294 295 // Does "A op B" simplify? 296 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { 297 // It does! Return "V op C" if it simplifies or is already available. 298 // If V equals B then "V op C" is just the RHS. 299 if (V == B) return RHS; 300 // Otherwise return "V op C" if it simplifies. 301 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { 302 ++NumReassoc; 303 return W; 304 } 305 } 306 } 307 308 // The remaining transforms require commutativity as well as associativity. 309 if (!Instruction::isCommutative(Opcode)) 310 return 0; 311 312 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 313 if (Op0 && Op0->getOpcode() == Opcode) { 314 Value *A = Op0->getOperand(0); 315 Value *B = Op0->getOperand(1); 316 Value *C = RHS; 317 318 // Does "C op A" simplify? 319 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 320 // It does! Return "V op B" if it simplifies or is already available. 321 // If V equals A then "V op B" is just the LHS. 322 if (V == A) return LHS; 323 // Otherwise return "V op B" if it simplifies. 324 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { 325 ++NumReassoc; 326 return W; 327 } 328 } 329 } 330 331 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 332 if (Op1 && Op1->getOpcode() == Opcode) { 333 Value *A = LHS; 334 Value *B = Op1->getOperand(0); 335 Value *C = Op1->getOperand(1); 336 337 // Does "C op A" simplify? 338 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 339 // It does! Return "B op V" if it simplifies or is already available. 340 // If V equals C then "B op V" is just the RHS. 341 if (V == C) return RHS; 342 // Otherwise return "B op V" if it simplifies. 343 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { 344 ++NumReassoc; 345 return W; 346 } 347 } 348 } 349 350 return 0; 351} 352 353/// ThreadBinOpOverSelect - In the case of a binary operation with a select 354/// instruction as an operand, try to simplify the binop by seeing whether 355/// evaluating it on both branches of the select results in the same value. 356/// Returns the common value if so, otherwise returns null. 357static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS, 358 const Query &Q, unsigned MaxRecurse) { 359 // Recursion is always used, so bail out at once if we already hit the limit. 360 if (!MaxRecurse--) 361 return 0; 362 363 SelectInst *SI; 364 if (isa<SelectInst>(LHS)) { 365 SI = cast<SelectInst>(LHS); 366 } else { 367 assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 368 SI = cast<SelectInst>(RHS); 369 } 370 371 // Evaluate the BinOp on the true and false branches of the select. 372 Value *TV; 373 Value *FV; 374 if (SI == LHS) { 375 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); 376 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); 377 } else { 378 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); 379 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); 380 } 381 382 // If they simplified to the same value, then return the common value. 383 // If they both failed to simplify then return null. 384 if (TV == FV) 385 return TV; 386 387 // If one branch simplified to undef, return the other one. 388 if (TV && isa<UndefValue>(TV)) 389 return FV; 390 if (FV && isa<UndefValue>(FV)) 391 return TV; 392 393 // If applying the operation did not change the true and false select values, 394 // then the result of the binop is the select itself. 395 if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 396 return SI; 397 398 // If one branch simplified and the other did not, and the simplified 399 // value is equal to the unsimplified one, return the simplified value. 400 // For example, select (cond, X, X & Z) & Z -> X & Z. 401 if ((FV && !TV) || (TV && !FV)) { 402 // Check that the simplified value has the form "X op Y" where "op" is the 403 // same as the original operation. 404 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 405 if (Simplified && Simplified->getOpcode() == Opcode) { 406 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 407 // We already know that "op" is the same as for the simplified value. See 408 // if the operands match too. If so, return the simplified value. 409 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 410 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 411 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 412 if (Simplified->getOperand(0) == UnsimplifiedLHS && 413 Simplified->getOperand(1) == UnsimplifiedRHS) 414 return Simplified; 415 if (Simplified->isCommutative() && 416 Simplified->getOperand(1) == UnsimplifiedLHS && 417 Simplified->getOperand(0) == UnsimplifiedRHS) 418 return Simplified; 419 } 420 } 421 422 return 0; 423} 424 425/// ThreadCmpOverSelect - In the case of a comparison with a select instruction, 426/// try to simplify the comparison by seeing whether both branches of the select 427/// result in the same value. Returns the common value if so, otherwise returns 428/// null. 429static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 430 Value *RHS, const Query &Q, 431 unsigned MaxRecurse) { 432 // Recursion is always used, so bail out at once if we already hit the limit. 433 if (!MaxRecurse--) 434 return 0; 435 436 // Make sure the select is on the LHS. 437 if (!isa<SelectInst>(LHS)) { 438 std::swap(LHS, RHS); 439 Pred = CmpInst::getSwappedPredicate(Pred); 440 } 441 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 442 SelectInst *SI = cast<SelectInst>(LHS); 443 Value *Cond = SI->getCondition(); 444 Value *TV = SI->getTrueValue(); 445 Value *FV = SI->getFalseValue(); 446 447 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 448 // Does "cmp TV, RHS" simplify? 449 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse); 450 if (TCmp == Cond) { 451 // It not only simplified, it simplified to the select condition. Replace 452 // it with 'true'. 453 TCmp = getTrue(Cond->getType()); 454 } else if (!TCmp) { 455 // It didn't simplify. However if "cmp TV, RHS" is equal to the select 456 // condition then we can replace it with 'true'. Otherwise give up. 457 if (!isSameCompare(Cond, Pred, TV, RHS)) 458 return 0; 459 TCmp = getTrue(Cond->getType()); 460 } 461 462 // Does "cmp FV, RHS" simplify? 463 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse); 464 if (FCmp == Cond) { 465 // It not only simplified, it simplified to the select condition. Replace 466 // it with 'false'. 467 FCmp = getFalse(Cond->getType()); 468 } else if (!FCmp) { 469 // It didn't simplify. However if "cmp FV, RHS" is equal to the select 470 // condition then we can replace it with 'false'. Otherwise give up. 471 if (!isSameCompare(Cond, Pred, FV, RHS)) 472 return 0; 473 FCmp = getFalse(Cond->getType()); 474 } 475 476 // If both sides simplified to the same value, then use it as the result of 477 // the original comparison. 478 if (TCmp == FCmp) 479 return TCmp; 480 481 // The remaining cases only make sense if the select condition has the same 482 // type as the result of the comparison, so bail out if this is not so. 483 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy()) 484 return 0; 485 // If the false value simplified to false, then the result of the compare 486 // is equal to "Cond && TCmp". This also catches the case when the false 487 // value simplified to false and the true value to true, returning "Cond". 488 if (match(FCmp, m_Zero())) 489 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse)) 490 return V; 491 // If the true value simplified to true, then the result of the compare 492 // is equal to "Cond || FCmp". 493 if (match(TCmp, m_One())) 494 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse)) 495 return V; 496 // Finally, if the false value simplified to true and the true value to 497 // false, then the result of the compare is equal to "!Cond". 498 if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 499 if (Value *V = 500 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()), 501 Q, MaxRecurse)) 502 return V; 503 504 return 0; 505} 506 507/// ThreadBinOpOverPHI - In the case of a binary operation with an operand that 508/// is a PHI instruction, try to simplify the binop by seeing whether evaluating 509/// it on the incoming phi values yields the same result for every value. If so 510/// returns the common value, otherwise returns null. 511static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS, 512 const Query &Q, unsigned MaxRecurse) { 513 // Recursion is always used, so bail out at once if we already hit the limit. 514 if (!MaxRecurse--) 515 return 0; 516 517 PHINode *PI; 518 if (isa<PHINode>(LHS)) { 519 PI = cast<PHINode>(LHS); 520 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 521 if (!ValueDominatesPHI(RHS, PI, Q.DT)) 522 return 0; 523 } else { 524 assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 525 PI = cast<PHINode>(RHS); 526 // Bail out if LHS and the phi may be mutually interdependent due to a loop. 527 if (!ValueDominatesPHI(LHS, PI, Q.DT)) 528 return 0; 529 } 530 531 // Evaluate the BinOp on the incoming phi values. 532 Value *CommonValue = 0; 533 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { 534 Value *Incoming = PI->getIncomingValue(i); 535 // If the incoming value is the phi node itself, it can safely be skipped. 536 if (Incoming == PI) continue; 537 Value *V = PI == LHS ? 538 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) : 539 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse); 540 // If the operation failed to simplify, or simplified to a different value 541 // to previously, then give up. 542 if (!V || (CommonValue && V != CommonValue)) 543 return 0; 544 CommonValue = V; 545 } 546 547 return CommonValue; 548} 549 550/// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try 551/// try to simplify the comparison by seeing whether comparing with all of the 552/// incoming phi values yields the same result every time. If so returns the 553/// common result, otherwise returns null. 554static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 555 const Query &Q, unsigned MaxRecurse) { 556 // Recursion is always used, so bail out at once if we already hit the limit. 557 if (!MaxRecurse--) 558 return 0; 559 560 // Make sure the phi is on the LHS. 561 if (!isa<PHINode>(LHS)) { 562 std::swap(LHS, RHS); 563 Pred = CmpInst::getSwappedPredicate(Pred); 564 } 565 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 566 PHINode *PI = cast<PHINode>(LHS); 567 568 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 569 if (!ValueDominatesPHI(RHS, PI, Q.DT)) 570 return 0; 571 572 // Evaluate the BinOp on the incoming phi values. 573 Value *CommonValue = 0; 574 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { 575 Value *Incoming = PI->getIncomingValue(i); 576 // If the incoming value is the phi node itself, it can safely be skipped. 577 if (Incoming == PI) continue; 578 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse); 579 // If the operation failed to simplify, or simplified to a different value 580 // to previously, then give up. 581 if (!V || (CommonValue && V != CommonValue)) 582 return 0; 583 CommonValue = V; 584 } 585 586 return CommonValue; 587} 588 589/// SimplifyAddInst - Given operands for an Add, see if we can 590/// fold the result. If not, this returns null. 591static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 592 const Query &Q, unsigned MaxRecurse) { 593 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 594 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 595 Constant *Ops[] = { CLHS, CRHS }; 596 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops, 597 Q.TD, Q.TLI); 598 } 599 600 // Canonicalize the constant to the RHS. 601 std::swap(Op0, Op1); 602 } 603 604 // X + undef -> undef 605 if (match(Op1, m_Undef())) 606 return Op1; 607 608 // X + 0 -> X 609 if (match(Op1, m_Zero())) 610 return Op0; 611 612 // X + (Y - X) -> Y 613 // (Y - X) + X -> Y 614 // Eg: X + -X -> 0 615 Value *Y = 0; 616 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 617 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 618 return Y; 619 620 // X + ~X -> -1 since ~X = -X-1 621 if (match(Op0, m_Not(m_Specific(Op1))) || 622 match(Op1, m_Not(m_Specific(Op0)))) 623 return Constant::getAllOnesValue(Op0->getType()); 624 625 /// i1 add -> xor. 626 if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 627 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 628 return V; 629 630 // Try some generic simplifications for associative operations. 631 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, 632 MaxRecurse)) 633 return V; 634 635 // Mul distributes over Add. Try some generic simplifications based on this. 636 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul, 637 Q, MaxRecurse)) 638 return V; 639 640 // Threading Add over selects and phi nodes is pointless, so don't bother. 641 // Threading over the select in "A + select(cond, B, C)" means evaluating 642 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 643 // only if B and C are equal. If B and C are equal then (since we assume 644 // that operands have already been simplified) "select(cond, B, C)" should 645 // have been simplified to the common value of B and C already. Analysing 646 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 647 // for threading over phi nodes. 648 649 return 0; 650} 651 652Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 653 const TargetData *TD, const TargetLibraryInfo *TLI, 654 const DominatorTree *DT) { 655 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), 656 RecursionLimit); 657} 658 659/// \brief Accumulate the constant integer offset a GEP represents. 660/// 661/// Given a getelementptr instruction/constantexpr, accumulate the constant 662/// offset from the base pointer into the provided APInt 'Offset'. Returns true 663/// if the GEP has all-constant indices. Returns false if any non-constant 664/// index is encountered leaving the 'Offset' in an undefined state. The 665/// 'Offset' APInt must be the bitwidth of the target's pointer size. 666static bool accumulateGEPOffset(const TargetData &TD, GEPOperator *GEP, 667 APInt &Offset) { 668 unsigned IntPtrWidth = TD.getPointerSizeInBits(); 669 assert(IntPtrWidth == Offset.getBitWidth()); 670 671 gep_type_iterator GTI = gep_type_begin(GEP); 672 for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E; 673 ++I, ++GTI) { 674 ConstantInt *OpC = dyn_cast<ConstantInt>(*I); 675 if (!OpC) return false; 676 if (OpC->isZero()) continue; 677 678 // Handle a struct index, which adds its field offset to the pointer. 679 if (StructType *STy = dyn_cast<StructType>(*GTI)) { 680 unsigned ElementIdx = OpC->getZExtValue(); 681 const StructLayout *SL = TD.getStructLayout(STy); 682 Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx)); 683 continue; 684 } 685 686 APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType())); 687 Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize; 688 } 689 return true; 690} 691 692/// \brief Compute the base pointer and cumulative constant offsets for V. 693/// 694/// This strips all constant offsets off of V, leaving it the base pointer, and 695/// accumulates the total constant offset applied in the returned constant. It 696/// returns 0 if V is not a pointer, and returns the constant '0' if there are 697/// no constant offsets applied. 698static Constant *stripAndComputeConstantOffsets(const TargetData &TD, 699 Value *&V) { 700 if (!V->getType()->isPointerTy()) 701 return 0; 702 703 unsigned IntPtrWidth = TD.getPointerSizeInBits(); 704 APInt Offset = APInt::getNullValue(IntPtrWidth); 705 706 // Even though we don't look through PHI nodes, we could be called on an 707 // instruction in an unreachable block, which may be on a cycle. 708 SmallPtrSet<Value *, 4> Visited; 709 Visited.insert(V); 710 do { 711 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { 712 if (!accumulateGEPOffset(TD, GEP, Offset)) 713 break; 714 V = GEP->getPointerOperand(); 715 } else if (Operator::getOpcode(V) == Instruction::BitCast) { 716 V = cast<Operator>(V)->getOperand(0); 717 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { 718 if (GA->mayBeOverridden()) 719 break; 720 V = GA->getAliasee(); 721 } else { 722 break; 723 } 724 assert(V->getType()->isPointerTy() && "Unexpected operand type!"); 725 } while (Visited.insert(V)); 726 727 Type *IntPtrTy = TD.getIntPtrType(V->getContext()); 728 return ConstantInt::get(IntPtrTy, Offset); 729} 730 731/// \brief Compute the constant difference between two pointer values. 732/// If the difference is not a constant, returns zero. 733static Constant *computePointerDifference(const TargetData &TD, 734 Value *LHS, Value *RHS) { 735 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS); 736 if (!LHSOffset) 737 return 0; 738 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS); 739 if (!RHSOffset) 740 return 0; 741 742 // If LHS and RHS are not related via constant offsets to the same base 743 // value, there is nothing we can do here. 744 if (LHS != RHS) 745 return 0; 746 747 // Otherwise, the difference of LHS - RHS can be computed as: 748 // LHS - RHS 749 // = (LHSOffset + Base) - (RHSOffset + Base) 750 // = LHSOffset - RHSOffset 751 return ConstantExpr::getSub(LHSOffset, RHSOffset); 752} 753 754/// SimplifySubInst - Given operands for a Sub, see if we can 755/// fold the result. If not, this returns null. 756static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 757 const Query &Q, unsigned MaxRecurse) { 758 if (Constant *CLHS = dyn_cast<Constant>(Op0)) 759 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 760 Constant *Ops[] = { CLHS, CRHS }; 761 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(), 762 Ops, Q.TD, Q.TLI); 763 } 764 765 // X - undef -> undef 766 // undef - X -> undef 767 if (match(Op0, m_Undef()) || match(Op1, m_Undef())) 768 return UndefValue::get(Op0->getType()); 769 770 // X - 0 -> X 771 if (match(Op1, m_Zero())) 772 return Op0; 773 774 // X - X -> 0 775 if (Op0 == Op1) 776 return Constant::getNullValue(Op0->getType()); 777 778 // (X*2) - X -> X 779 // (X<<1) - X -> X 780 Value *X = 0; 781 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) || 782 match(Op0, m_Shl(m_Specific(Op1), m_One()))) 783 return Op1; 784 785 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 786 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 787 Value *Y = 0, *Z = Op1; 788 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 789 // See if "V === Y - Z" simplifies. 790 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1)) 791 // It does! Now see if "X + V" simplifies. 792 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) { 793 // It does, we successfully reassociated! 794 ++NumReassoc; 795 return W; 796 } 797 // See if "V === X - Z" simplifies. 798 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 799 // It does! Now see if "Y + V" simplifies. 800 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) { 801 // It does, we successfully reassociated! 802 ++NumReassoc; 803 return W; 804 } 805 } 806 807 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 808 // For example, X - (X + 1) -> -1 809 X = Op0; 810 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 811 // See if "V === X - Y" simplifies. 812 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 813 // It does! Now see if "V - Z" simplifies. 814 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) { 815 // It does, we successfully reassociated! 816 ++NumReassoc; 817 return W; 818 } 819 // See if "V === X - Z" simplifies. 820 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) 821 // It does! Now see if "V - Y" simplifies. 822 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) { 823 // It does, we successfully reassociated! 824 ++NumReassoc; 825 return W; 826 } 827 } 828 829 // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 830 // For example, X - (X - Y) -> Y. 831 Z = Op0; 832 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 833 // See if "V === Z - X" simplifies. 834 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1)) 835 // It does! Now see if "V + Y" simplifies. 836 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) { 837 // It does, we successfully reassociated! 838 ++NumReassoc; 839 return W; 840 } 841 842 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. 843 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && 844 match(Op1, m_Trunc(m_Value(Y)))) 845 if (X->getType() == Y->getType()) 846 // See if "V === X - Y" simplifies. 847 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) 848 // It does! Now see if "trunc V" simplifies. 849 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1)) 850 // It does, return the simplified "trunc V". 851 return W; 852 853 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). 854 if (Q.TD && match(Op0, m_PtrToInt(m_Value(X))) && 855 match(Op1, m_PtrToInt(m_Value(Y)))) 856 if (Constant *Result = computePointerDifference(*Q.TD, X, Y)) 857 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true); 858 859 // Mul distributes over Sub. Try some generic simplifications based on this. 860 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul, 861 Q, MaxRecurse)) 862 return V; 863 864 // i1 sub -> xor. 865 if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 866 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) 867 return V; 868 869 // Threading Sub over selects and phi nodes is pointless, so don't bother. 870 // Threading over the select in "A - select(cond, B, C)" means evaluating 871 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 872 // only if B and C are equal. If B and C are equal then (since we assume 873 // that operands have already been simplified) "select(cond, B, C)" should 874 // have been simplified to the common value of B and C already. Analysing 875 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 876 // for threading over phi nodes. 877 878 return 0; 879} 880 881Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 882 const TargetData *TD, const TargetLibraryInfo *TLI, 883 const DominatorTree *DT) { 884 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), 885 RecursionLimit); 886} 887 888/// SimplifyMulInst - Given operands for a Mul, see if we can 889/// fold the result. If not, this returns null. 890static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q, 891 unsigned MaxRecurse) { 892 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 893 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 894 Constant *Ops[] = { CLHS, CRHS }; 895 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(), 896 Ops, Q.TD, Q.TLI); 897 } 898 899 // Canonicalize the constant to the RHS. 900 std::swap(Op0, Op1); 901 } 902 903 // X * undef -> 0 904 if (match(Op1, m_Undef())) 905 return Constant::getNullValue(Op0->getType()); 906 907 // X * 0 -> 0 908 if (match(Op1, m_Zero())) 909 return Op1; 910 911 // X * 1 -> X 912 if (match(Op1, m_One())) 913 return Op0; 914 915 // (X / Y) * Y -> X if the division is exact. 916 Value *X = 0; 917 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y 918 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y) 919 return X; 920 921 // i1 mul -> and. 922 if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 923 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1)) 924 return V; 925 926 // Try some generic simplifications for associative operations. 927 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, 928 MaxRecurse)) 929 return V; 930 931 // Mul distributes over Add. Try some generic simplifications based on this. 932 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add, 933 Q, MaxRecurse)) 934 return V; 935 936 // If the operation is with the result of a select instruction, check whether 937 // operating on either branch of the select always yields the same value. 938 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 939 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, 940 MaxRecurse)) 941 return V; 942 943 // If the operation is with the result of a phi instruction, check whether 944 // operating on all incoming values of the phi always yields the same value. 945 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 946 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, 947 MaxRecurse)) 948 return V; 949 950 return 0; 951} 952 953Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD, 954 const TargetLibraryInfo *TLI, 955 const DominatorTree *DT) { 956 return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 957} 958 959/// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can 960/// fold the result. If not, this returns null. 961static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 962 const Query &Q, unsigned MaxRecurse) { 963 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 964 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 965 Constant *Ops[] = { C0, C1 }; 966 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); 967 } 968 } 969 970 bool isSigned = Opcode == Instruction::SDiv; 971 972 // X / undef -> undef 973 if (match(Op1, m_Undef())) 974 return Op1; 975 976 // undef / X -> 0 977 if (match(Op0, m_Undef())) 978 return Constant::getNullValue(Op0->getType()); 979 980 // 0 / X -> 0, we don't need to preserve faults! 981 if (match(Op0, m_Zero())) 982 return Op0; 983 984 // X / 1 -> X 985 if (match(Op1, m_One())) 986 return Op0; 987 988 if (Op0->getType()->isIntegerTy(1)) 989 // It can't be division by zero, hence it must be division by one. 990 return Op0; 991 992 // X / X -> 1 993 if (Op0 == Op1) 994 return ConstantInt::get(Op0->getType(), 1); 995 996 // (X * Y) / Y -> X if the multiplication does not overflow. 997 Value *X = 0, *Y = 0; 998 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) { 999 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1 1000 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0); 1001 // If the Mul knows it does not overflow, then we are good to go. 1002 if ((isSigned && Mul->hasNoSignedWrap()) || 1003 (!isSigned && Mul->hasNoUnsignedWrap())) 1004 return X; 1005 // If X has the form X = A / Y then X * Y cannot overflow. 1006 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X)) 1007 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y) 1008 return X; 1009 } 1010 1011 // (X rem Y) / Y -> 0 1012 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || 1013 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1))))) 1014 return Constant::getNullValue(Op0->getType()); 1015 1016 // If the operation is with the result of a select instruction, check whether 1017 // operating on either branch of the select always yields the same value. 1018 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1019 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1020 return V; 1021 1022 // If the operation is with the result of a phi instruction, check whether 1023 // operating on all incoming values of the phi always yields the same value. 1024 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1025 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1026 return V; 1027 1028 return 0; 1029} 1030 1031/// SimplifySDivInst - Given operands for an SDiv, see if we can 1032/// fold the result. If not, this returns null. 1033static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q, 1034 unsigned MaxRecurse) { 1035 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse)) 1036 return V; 1037 1038 return 0; 1039} 1040 1041Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD, 1042 const TargetLibraryInfo *TLI, 1043 const DominatorTree *DT) { 1044 return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1045} 1046 1047/// SimplifyUDivInst - Given operands for a UDiv, see if we can 1048/// fold the result. If not, this returns null. 1049static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q, 1050 unsigned MaxRecurse) { 1051 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse)) 1052 return V; 1053 1054 return 0; 1055} 1056 1057Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD, 1058 const TargetLibraryInfo *TLI, 1059 const DominatorTree *DT) { 1060 return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1061} 1062 1063static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q, 1064 unsigned) { 1065 // undef / X -> undef (the undef could be a snan). 1066 if (match(Op0, m_Undef())) 1067 return Op0; 1068 1069 // X / undef -> undef 1070 if (match(Op1, m_Undef())) 1071 return Op1; 1072 1073 return 0; 1074} 1075 1076Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD, 1077 const TargetLibraryInfo *TLI, 1078 const DominatorTree *DT) { 1079 return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1080} 1081 1082/// SimplifyRem - Given operands for an SRem or URem, see if we can 1083/// fold the result. If not, this returns null. 1084static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1085 const Query &Q, unsigned MaxRecurse) { 1086 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 1087 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 1088 Constant *Ops[] = { C0, C1 }; 1089 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); 1090 } 1091 } 1092 1093 // X % undef -> undef 1094 if (match(Op1, m_Undef())) 1095 return Op1; 1096 1097 // undef % X -> 0 1098 if (match(Op0, m_Undef())) 1099 return Constant::getNullValue(Op0->getType()); 1100 1101 // 0 % X -> 0, we don't need to preserve faults! 1102 if (match(Op0, m_Zero())) 1103 return Op0; 1104 1105 // X % 0 -> undef, we don't need to preserve faults! 1106 if (match(Op1, m_Zero())) 1107 return UndefValue::get(Op0->getType()); 1108 1109 // X % 1 -> 0 1110 if (match(Op1, m_One())) 1111 return Constant::getNullValue(Op0->getType()); 1112 1113 if (Op0->getType()->isIntegerTy(1)) 1114 // It can't be remainder by zero, hence it must be remainder by one. 1115 return Constant::getNullValue(Op0->getType()); 1116 1117 // X % X -> 0 1118 if (Op0 == Op1) 1119 return Constant::getNullValue(Op0->getType()); 1120 1121 // If the operation is with the result of a select instruction, check whether 1122 // operating on either branch of the select always yields the same value. 1123 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1124 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1125 return V; 1126 1127 // If the operation is with the result of a phi instruction, check whether 1128 // operating on all incoming values of the phi always yields the same value. 1129 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1130 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1131 return V; 1132 1133 return 0; 1134} 1135 1136/// SimplifySRemInst - Given operands for an SRem, see if we can 1137/// fold the result. If not, this returns null. 1138static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q, 1139 unsigned MaxRecurse) { 1140 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse)) 1141 return V; 1142 1143 return 0; 1144} 1145 1146Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD, 1147 const TargetLibraryInfo *TLI, 1148 const DominatorTree *DT) { 1149 return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1150} 1151 1152/// SimplifyURemInst - Given operands for a URem, see if we can 1153/// fold the result. If not, this returns null. 1154static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q, 1155 unsigned MaxRecurse) { 1156 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse)) 1157 return V; 1158 1159 return 0; 1160} 1161 1162Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD, 1163 const TargetLibraryInfo *TLI, 1164 const DominatorTree *DT) { 1165 return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1166} 1167 1168static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &, 1169 unsigned) { 1170 // undef % X -> undef (the undef could be a snan). 1171 if (match(Op0, m_Undef())) 1172 return Op0; 1173 1174 // X % undef -> undef 1175 if (match(Op1, m_Undef())) 1176 return Op1; 1177 1178 return 0; 1179} 1180 1181Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD, 1182 const TargetLibraryInfo *TLI, 1183 const DominatorTree *DT) { 1184 return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1185} 1186 1187/// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can 1188/// fold the result. If not, this returns null. 1189static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1, 1190 const Query &Q, unsigned MaxRecurse) { 1191 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 1192 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 1193 Constant *Ops[] = { C0, C1 }; 1194 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); 1195 } 1196 } 1197 1198 // 0 shift by X -> 0 1199 if (match(Op0, m_Zero())) 1200 return Op0; 1201 1202 // X shift by 0 -> X 1203 if (match(Op1, m_Zero())) 1204 return Op0; 1205 1206 // X shift by undef -> undef because it may shift by the bitwidth. 1207 if (match(Op1, m_Undef())) 1208 return Op1; 1209 1210 // Shifting by the bitwidth or more is undefined. 1211 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) 1212 if (CI->getValue().getLimitedValue() >= 1213 Op0->getType()->getScalarSizeInBits()) 1214 return UndefValue::get(Op0->getType()); 1215 1216 // If the operation is with the result of a select instruction, check whether 1217 // operating on either branch of the select always yields the same value. 1218 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1219 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1220 return V; 1221 1222 // If the operation is with the result of a phi instruction, check whether 1223 // operating on all incoming values of the phi always yields the same value. 1224 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1225 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1226 return V; 1227 1228 return 0; 1229} 1230 1231/// SimplifyShlInst - Given operands for an Shl, see if we can 1232/// fold the result. If not, this returns null. 1233static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1234 const Query &Q, unsigned MaxRecurse) { 1235 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse)) 1236 return V; 1237 1238 // undef << X -> 0 1239 if (match(Op0, m_Undef())) 1240 return Constant::getNullValue(Op0->getType()); 1241 1242 // (X >> A) << A -> X 1243 Value *X; 1244 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) 1245 return X; 1246 return 0; 1247} 1248 1249Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1250 const TargetData *TD, const TargetLibraryInfo *TLI, 1251 const DominatorTree *DT) { 1252 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), 1253 RecursionLimit); 1254} 1255 1256/// SimplifyLShrInst - Given operands for an LShr, see if we can 1257/// fold the result. If not, this returns null. 1258static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1259 const Query &Q, unsigned MaxRecurse) { 1260 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse)) 1261 return V; 1262 1263 // undef >>l X -> 0 1264 if (match(Op0, m_Undef())) 1265 return Constant::getNullValue(Op0->getType()); 1266 1267 // (X << A) >> A -> X 1268 Value *X; 1269 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && 1270 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap()) 1271 return X; 1272 1273 return 0; 1274} 1275 1276Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1277 const TargetData *TD, 1278 const TargetLibraryInfo *TLI, 1279 const DominatorTree *DT) { 1280 return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT), 1281 RecursionLimit); 1282} 1283 1284/// SimplifyAShrInst - Given operands for an AShr, see if we can 1285/// fold the result. If not, this returns null. 1286static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1287 const Query &Q, unsigned MaxRecurse) { 1288 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse)) 1289 return V; 1290 1291 // all ones >>a X -> all ones 1292 if (match(Op0, m_AllOnes())) 1293 return Op0; 1294 1295 // undef >>a X -> all ones 1296 if (match(Op0, m_Undef())) 1297 return Constant::getAllOnesValue(Op0->getType()); 1298 1299 // (X << A) >> A -> X 1300 Value *X; 1301 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && 1302 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap()) 1303 return X; 1304 1305 return 0; 1306} 1307 1308Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1309 const TargetData *TD, 1310 const TargetLibraryInfo *TLI, 1311 const DominatorTree *DT) { 1312 return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT), 1313 RecursionLimit); 1314} 1315 1316/// SimplifyAndInst - Given operands for an And, see if we can 1317/// fold the result. If not, this returns null. 1318static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q, 1319 unsigned MaxRecurse) { 1320 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1321 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1322 Constant *Ops[] = { CLHS, CRHS }; 1323 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(), 1324 Ops, Q.TD, Q.TLI); 1325 } 1326 1327 // Canonicalize the constant to the RHS. 1328 std::swap(Op0, Op1); 1329 } 1330 1331 // X & undef -> 0 1332 if (match(Op1, m_Undef())) 1333 return Constant::getNullValue(Op0->getType()); 1334 1335 // X & X = X 1336 if (Op0 == Op1) 1337 return Op0; 1338 1339 // X & 0 = 0 1340 if (match(Op1, m_Zero())) 1341 return Op1; 1342 1343 // X & -1 = X 1344 if (match(Op1, m_AllOnes())) 1345 return Op0; 1346 1347 // A & ~A = ~A & A = 0 1348 if (match(Op0, m_Not(m_Specific(Op1))) || 1349 match(Op1, m_Not(m_Specific(Op0)))) 1350 return Constant::getNullValue(Op0->getType()); 1351 1352 // (A | ?) & A = A 1353 Value *A = 0, *B = 0; 1354 if (match(Op0, m_Or(m_Value(A), m_Value(B))) && 1355 (A == Op1 || B == Op1)) 1356 return Op1; 1357 1358 // A & (A | ?) = A 1359 if (match(Op1, m_Or(m_Value(A), m_Value(B))) && 1360 (A == Op0 || B == Op0)) 1361 return Op0; 1362 1363 // A & (-A) = A if A is a power of two or zero. 1364 if (match(Op0, m_Neg(m_Specific(Op1))) || 1365 match(Op1, m_Neg(m_Specific(Op0)))) { 1366 if (isPowerOfTwo(Op0, Q.TD, /*OrZero*/true)) 1367 return Op0; 1368 if (isPowerOfTwo(Op1, Q.TD, /*OrZero*/true)) 1369 return Op1; 1370 } 1371 1372 // Try some generic simplifications for associative operations. 1373 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, 1374 MaxRecurse)) 1375 return V; 1376 1377 // And distributes over Or. Try some generic simplifications based on this. 1378 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or, 1379 Q, MaxRecurse)) 1380 return V; 1381 1382 // And distributes over Xor. Try some generic simplifications based on this. 1383 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor, 1384 Q, MaxRecurse)) 1385 return V; 1386 1387 // Or distributes over And. Try some generic simplifications based on this. 1388 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or, 1389 Q, MaxRecurse)) 1390 return V; 1391 1392 // If the operation is with the result of a select instruction, check whether 1393 // operating on either branch of the select always yields the same value. 1394 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1395 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q, 1396 MaxRecurse)) 1397 return V; 1398 1399 // If the operation is with the result of a phi instruction, check whether 1400 // operating on all incoming values of the phi always yields the same value. 1401 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1402 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q, 1403 MaxRecurse)) 1404 return V; 1405 1406 return 0; 1407} 1408 1409Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD, 1410 const TargetLibraryInfo *TLI, 1411 const DominatorTree *DT) { 1412 return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1413} 1414 1415/// SimplifyOrInst - Given operands for an Or, see if we can 1416/// fold the result. If not, this returns null. 1417static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q, 1418 unsigned MaxRecurse) { 1419 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1420 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1421 Constant *Ops[] = { CLHS, CRHS }; 1422 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(), 1423 Ops, Q.TD, Q.TLI); 1424 } 1425 1426 // Canonicalize the constant to the RHS. 1427 std::swap(Op0, Op1); 1428 } 1429 1430 // X | undef -> -1 1431 if (match(Op1, m_Undef())) 1432 return Constant::getAllOnesValue(Op0->getType()); 1433 1434 // X | X = X 1435 if (Op0 == Op1) 1436 return Op0; 1437 1438 // X | 0 = X 1439 if (match(Op1, m_Zero())) 1440 return Op0; 1441 1442 // X | -1 = -1 1443 if (match(Op1, m_AllOnes())) 1444 return Op1; 1445 1446 // A | ~A = ~A | A = -1 1447 if (match(Op0, m_Not(m_Specific(Op1))) || 1448 match(Op1, m_Not(m_Specific(Op0)))) 1449 return Constant::getAllOnesValue(Op0->getType()); 1450 1451 // (A & ?) | A = A 1452 Value *A = 0, *B = 0; 1453 if (match(Op0, m_And(m_Value(A), m_Value(B))) && 1454 (A == Op1 || B == Op1)) 1455 return Op1; 1456 1457 // A | (A & ?) = A 1458 if (match(Op1, m_And(m_Value(A), m_Value(B))) && 1459 (A == Op0 || B == Op0)) 1460 return Op0; 1461 1462 // ~(A & ?) | A = -1 1463 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) && 1464 (A == Op1 || B == Op1)) 1465 return Constant::getAllOnesValue(Op1->getType()); 1466 1467 // A | ~(A & ?) = -1 1468 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) && 1469 (A == Op0 || B == Op0)) 1470 return Constant::getAllOnesValue(Op0->getType()); 1471 1472 // Try some generic simplifications for associative operations. 1473 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, 1474 MaxRecurse)) 1475 return V; 1476 1477 // Or distributes over And. Try some generic simplifications based on this. 1478 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q, 1479 MaxRecurse)) 1480 return V; 1481 1482 // And distributes over Or. Try some generic simplifications based on this. 1483 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And, 1484 Q, MaxRecurse)) 1485 return V; 1486 1487 // If the operation is with the result of a select instruction, check whether 1488 // operating on either branch of the select always yields the same value. 1489 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1490 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, 1491 MaxRecurse)) 1492 return V; 1493 1494 // If the operation is with the result of a phi instruction, check whether 1495 // operating on all incoming values of the phi always yields the same value. 1496 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1497 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 1498 return V; 1499 1500 return 0; 1501} 1502 1503Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD, 1504 const TargetLibraryInfo *TLI, 1505 const DominatorTree *DT) { 1506 return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1507} 1508 1509/// SimplifyXorInst - Given operands for a Xor, see if we can 1510/// fold the result. If not, this returns null. 1511static Value *SimplifyXorInst(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::Xor, 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 // A ^ undef -> undef 1525 if (match(Op1, m_Undef())) 1526 return Op1; 1527 1528 // A ^ 0 = A 1529 if (match(Op1, m_Zero())) 1530 return Op0; 1531 1532 // A ^ A = 0 1533 if (Op0 == Op1) 1534 return Constant::getNullValue(Op0->getType()); 1535 1536 // A ^ ~A = ~A ^ A = -1 1537 if (match(Op0, m_Not(m_Specific(Op1))) || 1538 match(Op1, m_Not(m_Specific(Op0)))) 1539 return Constant::getAllOnesValue(Op0->getType()); 1540 1541 // Try some generic simplifications for associative operations. 1542 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, 1543 MaxRecurse)) 1544 return V; 1545 1546 // And distributes over Xor. Try some generic simplifications based on this. 1547 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And, 1548 Q, MaxRecurse)) 1549 return V; 1550 1551 // Threading Xor over selects and phi nodes is pointless, so don't bother. 1552 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 1553 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 1554 // only if B and C are equal. If B and C are equal then (since we assume 1555 // that operands have already been simplified) "select(cond, B, C)" should 1556 // have been simplified to the common value of B and C already. Analysing 1557 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 1558 // for threading over phi nodes. 1559 1560 return 0; 1561} 1562 1563Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD, 1564 const TargetLibraryInfo *TLI, 1565 const DominatorTree *DT) { 1566 return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); 1567} 1568 1569static Type *GetCompareTy(Value *Op) { 1570 return CmpInst::makeCmpResultType(Op->getType()); 1571} 1572 1573/// ExtractEquivalentCondition - Rummage around inside V looking for something 1574/// equivalent to the comparison "LHS Pred RHS". Return such a value if found, 1575/// otherwise return null. Helper function for analyzing max/min idioms. 1576static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 1577 Value *LHS, Value *RHS) { 1578 SelectInst *SI = dyn_cast<SelectInst>(V); 1579 if (!SI) 1580 return 0; 1581 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 1582 if (!Cmp) 1583 return 0; 1584 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 1585 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 1586 return Cmp; 1587 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 1588 LHS == CmpRHS && RHS == CmpLHS) 1589 return Cmp; 1590 return 0; 1591} 1592 1593 1594/// SimplifyICmpInst - Given operands for an ICmpInst, see if we can 1595/// fold the result. If not, this returns null. 1596static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 1597 const Query &Q, unsigned MaxRecurse) { 1598 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 1599 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 1600 1601 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 1602 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 1603 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI); 1604 1605 // If we have a constant, make sure it is on the RHS. 1606 std::swap(LHS, RHS); 1607 Pred = CmpInst::getSwappedPredicate(Pred); 1608 } 1609 1610 Type *ITy = GetCompareTy(LHS); // The return type. 1611 Type *OpTy = LHS->getType(); // The operand type. 1612 1613 // icmp X, X -> true/false 1614 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false 1615 // because X could be 0. 1616 if (LHS == RHS || isa<UndefValue>(RHS)) 1617 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 1618 1619 // Special case logic when the operands have i1 type. 1620 if (OpTy->getScalarType()->isIntegerTy(1)) { 1621 switch (Pred) { 1622 default: break; 1623 case ICmpInst::ICMP_EQ: 1624 // X == 1 -> X 1625 if (match(RHS, m_One())) 1626 return LHS; 1627 break; 1628 case ICmpInst::ICMP_NE: 1629 // X != 0 -> X 1630 if (match(RHS, m_Zero())) 1631 return LHS; 1632 break; 1633 case ICmpInst::ICMP_UGT: 1634 // X >u 0 -> X 1635 if (match(RHS, m_Zero())) 1636 return LHS; 1637 break; 1638 case ICmpInst::ICMP_UGE: 1639 // X >=u 1 -> X 1640 if (match(RHS, m_One())) 1641 return LHS; 1642 break; 1643 case ICmpInst::ICMP_SLT: 1644 // X <s 0 -> X 1645 if (match(RHS, m_Zero())) 1646 return LHS; 1647 break; 1648 case ICmpInst::ICMP_SLE: 1649 // X <=s -1 -> X 1650 if (match(RHS, m_One())) 1651 return LHS; 1652 break; 1653 } 1654 } 1655 1656 // icmp <object*>, <object*/null> - Different identified objects have 1657 // different addresses (unless null), and what's more the address of an 1658 // identified local is never equal to another argument (again, barring null). 1659 // Note that generalizing to the case where LHS is a global variable address 1660 // or null is pointless, since if both LHS and RHS are constants then we 1661 // already constant folded the compare, and if only one of them is then we 1662 // moved it to RHS already. 1663 Value *LHSPtr = LHS->stripPointerCasts(); 1664 Value *RHSPtr = RHS->stripPointerCasts(); 1665 if (LHSPtr == RHSPtr) 1666 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 1667 1668 // Be more aggressive about stripping pointer adjustments when checking a 1669 // comparison of an alloca address to another object. We can rip off all 1670 // inbounds GEP operations, even if they are variable. 1671 LHSPtr = LHSPtr->stripInBoundsOffsets(); 1672 if (llvm::isIdentifiedObject(LHSPtr)) { 1673 RHSPtr = RHSPtr->stripInBoundsOffsets(); 1674 if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) { 1675 // If both sides are different identified objects, they aren't equal 1676 // unless they're null. 1677 if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) && 1678 Pred == CmpInst::ICMP_EQ) 1679 return ConstantInt::get(ITy, false); 1680 1681 // A local identified object (alloca or noalias call) can't equal any 1682 // incoming argument, unless they're both null. 1683 if (isa<Instruction>(LHSPtr) && isa<Argument>(RHSPtr) && 1684 Pred == CmpInst::ICMP_EQ) 1685 return ConstantInt::get(ITy, false); 1686 } 1687 1688 // Assume that the constant null is on the right. 1689 if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) { 1690 if (Pred == CmpInst::ICMP_EQ) 1691 return ConstantInt::get(ITy, false); 1692 else if (Pred == CmpInst::ICMP_NE) 1693 return ConstantInt::get(ITy, true); 1694 } 1695 } else if (isa<Argument>(LHSPtr)) { 1696 RHSPtr = RHSPtr->stripInBoundsOffsets(); 1697 // An alloca can't be equal to an argument. 1698 if (isa<AllocaInst>(RHSPtr)) { 1699 if (Pred == CmpInst::ICMP_EQ) 1700 return ConstantInt::get(ITy, false); 1701 else if (Pred == CmpInst::ICMP_NE) 1702 return ConstantInt::get(ITy, true); 1703 } 1704 } 1705 1706 // If we are comparing with zero then try hard since this is a common case. 1707 if (match(RHS, m_Zero())) { 1708 bool LHSKnownNonNegative, LHSKnownNegative; 1709 switch (Pred) { 1710 default: llvm_unreachable("Unknown ICmp predicate!"); 1711 case ICmpInst::ICMP_ULT: 1712 return getFalse(ITy); 1713 case ICmpInst::ICMP_UGE: 1714 return getTrue(ITy); 1715 case ICmpInst::ICMP_EQ: 1716 case ICmpInst::ICMP_ULE: 1717 if (isKnownNonZero(LHS, Q.TD)) 1718 return getFalse(ITy); 1719 break; 1720 case ICmpInst::ICMP_NE: 1721 case ICmpInst::ICMP_UGT: 1722 if (isKnownNonZero(LHS, Q.TD)) 1723 return getTrue(ITy); 1724 break; 1725 case ICmpInst::ICMP_SLT: 1726 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1727 if (LHSKnownNegative) 1728 return getTrue(ITy); 1729 if (LHSKnownNonNegative) 1730 return getFalse(ITy); 1731 break; 1732 case ICmpInst::ICMP_SLE: 1733 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1734 if (LHSKnownNegative) 1735 return getTrue(ITy); 1736 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD)) 1737 return getFalse(ITy); 1738 break; 1739 case ICmpInst::ICMP_SGE: 1740 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1741 if (LHSKnownNegative) 1742 return getFalse(ITy); 1743 if (LHSKnownNonNegative) 1744 return getTrue(ITy); 1745 break; 1746 case ICmpInst::ICMP_SGT: 1747 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); 1748 if (LHSKnownNegative) 1749 return getFalse(ITy); 1750 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD)) 1751 return getTrue(ITy); 1752 break; 1753 } 1754 } 1755 1756 // See if we are doing a comparison with a constant integer. 1757 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 1758 // Rule out tautological comparisons (eg., ult 0 or uge 0). 1759 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue()); 1760 if (RHS_CR.isEmptySet()) 1761 return ConstantInt::getFalse(CI->getContext()); 1762 if (RHS_CR.isFullSet()) 1763 return ConstantInt::getTrue(CI->getContext()); 1764 1765 // Many binary operators with constant RHS have easy to compute constant 1766 // range. Use them to check whether the comparison is a tautology. 1767 uint32_t Width = CI->getBitWidth(); 1768 APInt Lower = APInt(Width, 0); 1769 APInt Upper = APInt(Width, 0); 1770 ConstantInt *CI2; 1771 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) { 1772 // 'urem x, CI2' produces [0, CI2). 1773 Upper = CI2->getValue(); 1774 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) { 1775 // 'srem x, CI2' produces (-|CI2|, |CI2|). 1776 Upper = CI2->getValue().abs(); 1777 Lower = (-Upper) + 1; 1778 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) { 1779 // 'udiv CI2, x' produces [0, CI2]. 1780 Upper = CI2->getValue() + 1; 1781 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) { 1782 // 'udiv x, CI2' produces [0, UINT_MAX / CI2]. 1783 APInt NegOne = APInt::getAllOnesValue(Width); 1784 if (!CI2->isZero()) 1785 Upper = NegOne.udiv(CI2->getValue()) + 1; 1786 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) { 1787 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]. 1788 APInt IntMin = APInt::getSignedMinValue(Width); 1789 APInt IntMax = APInt::getSignedMaxValue(Width); 1790 APInt Val = CI2->getValue().abs(); 1791 if (!Val.isMinValue()) { 1792 Lower = IntMin.sdiv(Val); 1793 Upper = IntMax.sdiv(Val) + 1; 1794 } 1795 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) { 1796 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2]. 1797 APInt NegOne = APInt::getAllOnesValue(Width); 1798 if (CI2->getValue().ult(Width)) 1799 Upper = NegOne.lshr(CI2->getValue()) + 1; 1800 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) { 1801 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2]. 1802 APInt IntMin = APInt::getSignedMinValue(Width); 1803 APInt IntMax = APInt::getSignedMaxValue(Width); 1804 if (CI2->getValue().ult(Width)) { 1805 Lower = IntMin.ashr(CI2->getValue()); 1806 Upper = IntMax.ashr(CI2->getValue()) + 1; 1807 } 1808 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) { 1809 // 'or x, CI2' produces [CI2, UINT_MAX]. 1810 Lower = CI2->getValue(); 1811 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) { 1812 // 'and x, CI2' produces [0, CI2]. 1813 Upper = CI2->getValue() + 1; 1814 } 1815 if (Lower != Upper) { 1816 ConstantRange LHS_CR = ConstantRange(Lower, Upper); 1817 if (RHS_CR.contains(LHS_CR)) 1818 return ConstantInt::getTrue(RHS->getContext()); 1819 if (RHS_CR.inverse().contains(LHS_CR)) 1820 return ConstantInt::getFalse(RHS->getContext()); 1821 } 1822 } 1823 1824 // Compare of cast, for example (zext X) != 0 -> X != 0 1825 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 1826 Instruction *LI = cast<CastInst>(LHS); 1827 Value *SrcOp = LI->getOperand(0); 1828 Type *SrcTy = SrcOp->getType(); 1829 Type *DstTy = LI->getType(); 1830 1831 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 1832 // if the integer type is the same size as the pointer type. 1833 if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) && 1834 Q.TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) { 1835 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 1836 // Transfer the cast to the constant. 1837 if (Value *V = SimplifyICmpInst(Pred, SrcOp, 1838 ConstantExpr::getIntToPtr(RHSC, SrcTy), 1839 Q, MaxRecurse-1)) 1840 return V; 1841 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 1842 if (RI->getOperand(0)->getType() == SrcTy) 1843 // Compare without the cast. 1844 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 1845 Q, MaxRecurse-1)) 1846 return V; 1847 } 1848 } 1849 1850 if (isa<ZExtInst>(LHS)) { 1851 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 1852 // same type. 1853 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 1854 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 1855 // Compare X and Y. Note that signed predicates become unsigned. 1856 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 1857 SrcOp, RI->getOperand(0), Q, 1858 MaxRecurse-1)) 1859 return V; 1860 } 1861 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 1862 // too. If not, then try to deduce the result of the comparison. 1863 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 1864 // Compute the constant that would happen if we truncated to SrcTy then 1865 // reextended to DstTy. 1866 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 1867 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy); 1868 1869 // If the re-extended constant didn't change then this is effectively 1870 // also a case of comparing two zero-extended values. 1871 if (RExt == CI && MaxRecurse) 1872 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 1873 SrcOp, Trunc, Q, MaxRecurse-1)) 1874 return V; 1875 1876 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 1877 // there. Use this to work out the result of the comparison. 1878 if (RExt != CI) { 1879 switch (Pred) { 1880 default: llvm_unreachable("Unknown ICmp predicate!"); 1881 // LHS <u RHS. 1882 case ICmpInst::ICMP_EQ: 1883 case ICmpInst::ICMP_UGT: 1884 case ICmpInst::ICMP_UGE: 1885 return ConstantInt::getFalse(CI->getContext()); 1886 1887 case ICmpInst::ICMP_NE: 1888 case ICmpInst::ICMP_ULT: 1889 case ICmpInst::ICMP_ULE: 1890 return ConstantInt::getTrue(CI->getContext()); 1891 1892 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 1893 // is non-negative then LHS <s RHS. 1894 case ICmpInst::ICMP_SGT: 1895 case ICmpInst::ICMP_SGE: 1896 return CI->getValue().isNegative() ? 1897 ConstantInt::getTrue(CI->getContext()) : 1898 ConstantInt::getFalse(CI->getContext()); 1899 1900 case ICmpInst::ICMP_SLT: 1901 case ICmpInst::ICMP_SLE: 1902 return CI->getValue().isNegative() ? 1903 ConstantInt::getFalse(CI->getContext()) : 1904 ConstantInt::getTrue(CI->getContext()); 1905 } 1906 } 1907 } 1908 } 1909 1910 if (isa<SExtInst>(LHS)) { 1911 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 1912 // same type. 1913 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 1914 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 1915 // Compare X and Y. Note that the predicate does not change. 1916 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 1917 Q, MaxRecurse-1)) 1918 return V; 1919 } 1920 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 1921 // too. If not, then try to deduce the result of the comparison. 1922 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 1923 // Compute the constant that would happen if we truncated to SrcTy then 1924 // reextended to DstTy. 1925 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 1926 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy); 1927 1928 // If the re-extended constant didn't change then this is effectively 1929 // also a case of comparing two sign-extended values. 1930 if (RExt == CI && MaxRecurse) 1931 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1)) 1932 return V; 1933 1934 // Otherwise the upper bits of LHS are all equal, while RHS has varying 1935 // bits there. Use this to work out the result of the comparison. 1936 if (RExt != CI) { 1937 switch (Pred) { 1938 default: llvm_unreachable("Unknown ICmp predicate!"); 1939 case ICmpInst::ICMP_EQ: 1940 return ConstantInt::getFalse(CI->getContext()); 1941 case ICmpInst::ICMP_NE: 1942 return ConstantInt::getTrue(CI->getContext()); 1943 1944 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 1945 // LHS >s RHS. 1946 case ICmpInst::ICMP_SGT: 1947 case ICmpInst::ICMP_SGE: 1948 return CI->getValue().isNegative() ? 1949 ConstantInt::getTrue(CI->getContext()) : 1950 ConstantInt::getFalse(CI->getContext()); 1951 case ICmpInst::ICMP_SLT: 1952 case ICmpInst::ICMP_SLE: 1953 return CI->getValue().isNegative() ? 1954 ConstantInt::getFalse(CI->getContext()) : 1955 ConstantInt::getTrue(CI->getContext()); 1956 1957 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 1958 // LHS >u RHS. 1959 case ICmpInst::ICMP_UGT: 1960 case ICmpInst::ICMP_UGE: 1961 // Comparison is true iff the LHS <s 0. 1962 if (MaxRecurse) 1963 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 1964 Constant::getNullValue(SrcTy), 1965 Q, MaxRecurse-1)) 1966 return V; 1967 break; 1968 case ICmpInst::ICMP_ULT: 1969 case ICmpInst::ICMP_ULE: 1970 // Comparison is true iff the LHS >=s 0. 1971 if (MaxRecurse) 1972 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 1973 Constant::getNullValue(SrcTy), 1974 Q, MaxRecurse-1)) 1975 return V; 1976 break; 1977 } 1978 } 1979 } 1980 } 1981 } 1982 1983 // Special logic for binary operators. 1984 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 1985 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 1986 if (MaxRecurse && (LBO || RBO)) { 1987 // Analyze the case when either LHS or RHS is an add instruction. 1988 Value *A = 0, *B = 0, *C = 0, *D = 0; 1989 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 1990 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 1991 if (LBO && LBO->getOpcode() == Instruction::Add) { 1992 A = LBO->getOperand(0); B = LBO->getOperand(1); 1993 NoLHSWrapProblem = ICmpInst::isEquality(Pred) || 1994 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) || 1995 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap()); 1996 } 1997 if (RBO && RBO->getOpcode() == Instruction::Add) { 1998 C = RBO->getOperand(0); D = RBO->getOperand(1); 1999 NoRHSWrapProblem = ICmpInst::isEquality(Pred) || 2000 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) || 2001 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap()); 2002 } 2003 2004 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 2005 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 2006 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A, 2007 Constant::getNullValue(RHS->getType()), 2008 Q, MaxRecurse-1)) 2009 return V; 2010 2011 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 2012 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 2013 if (Value *V = SimplifyICmpInst(Pred, 2014 Constant::getNullValue(LHS->getType()), 2015 C == LHS ? D : C, Q, MaxRecurse-1)) 2016 return V; 2017 2018 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 2019 if (A && C && (A == C || A == D || B == C || B == D) && 2020 NoLHSWrapProblem && NoRHSWrapProblem) { 2021 // Determine Y and Z in the form icmp (X+Y), (X+Z). 2022 Value *Y = (A == C || A == D) ? B : A; 2023 Value *Z = (C == A || C == B) ? D : C; 2024 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1)) 2025 return V; 2026 } 2027 } 2028 2029 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 2030 bool KnownNonNegative, KnownNegative; 2031 switch (Pred) { 2032 default: 2033 break; 2034 case ICmpInst::ICMP_SGT: 2035 case ICmpInst::ICMP_SGE: 2036 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD); 2037 if (!KnownNonNegative) 2038 break; 2039 // fall-through 2040 case ICmpInst::ICMP_EQ: 2041 case ICmpInst::ICMP_UGT: 2042 case ICmpInst::ICMP_UGE: 2043 return getFalse(ITy); 2044 case ICmpInst::ICMP_SLT: 2045 case ICmpInst::ICMP_SLE: 2046 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD); 2047 if (!KnownNonNegative) 2048 break; 2049 // fall-through 2050 case ICmpInst::ICMP_NE: 2051 case ICmpInst::ICMP_ULT: 2052 case ICmpInst::ICMP_ULE: 2053 return getTrue(ITy); 2054 } 2055 } 2056 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) { 2057 bool KnownNonNegative, KnownNegative; 2058 switch (Pred) { 2059 default: 2060 break; 2061 case ICmpInst::ICMP_SGT: 2062 case ICmpInst::ICMP_SGE: 2063 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD); 2064 if (!KnownNonNegative) 2065 break; 2066 // fall-through 2067 case ICmpInst::ICMP_NE: 2068 case ICmpInst::ICMP_UGT: 2069 case ICmpInst::ICMP_UGE: 2070 return getTrue(ITy); 2071 case ICmpInst::ICMP_SLT: 2072 case ICmpInst::ICMP_SLE: 2073 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD); 2074 if (!KnownNonNegative) 2075 break; 2076 // fall-through 2077 case ICmpInst::ICMP_EQ: 2078 case ICmpInst::ICMP_ULT: 2079 case ICmpInst::ICMP_ULE: 2080 return getFalse(ITy); 2081 } 2082 } 2083 2084 // x udiv y <=u x. 2085 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) { 2086 // icmp pred (X /u Y), X 2087 if (Pred == ICmpInst::ICMP_UGT) 2088 return getFalse(ITy); 2089 if (Pred == ICmpInst::ICMP_ULE) 2090 return getTrue(ITy); 2091 } 2092 2093 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() && 2094 LBO->getOperand(1) == RBO->getOperand(1)) { 2095 switch (LBO->getOpcode()) { 2096 default: break; 2097 case Instruction::UDiv: 2098 case Instruction::LShr: 2099 if (ICmpInst::isSigned(Pred)) 2100 break; 2101 // fall-through 2102 case Instruction::SDiv: 2103 case Instruction::AShr: 2104 if (!LBO->isExact() || !RBO->isExact()) 2105 break; 2106 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 2107 RBO->getOperand(0), Q, MaxRecurse-1)) 2108 return V; 2109 break; 2110 case Instruction::Shl: { 2111 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap(); 2112 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap(); 2113 if (!NUW && !NSW) 2114 break; 2115 if (!NSW && ICmpInst::isSigned(Pred)) 2116 break; 2117 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 2118 RBO->getOperand(0), Q, MaxRecurse-1)) 2119 return V; 2120 break; 2121 } 2122 } 2123 } 2124 2125 // Simplify comparisons involving max/min. 2126 Value *A, *B; 2127 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 2128 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 2129 2130 // Signed variants on "max(a,b)>=a -> true". 2131 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 2132 if (A != RHS) std::swap(A, B); // smax(A, B) pred A. 2133 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 2134 // We analyze this as smax(A, B) pred A. 2135 P = Pred; 2136 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 2137 (A == LHS || B == LHS)) { 2138 if (A != LHS) std::swap(A, B); // A pred smax(A, B). 2139 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 2140 // We analyze this as smax(A, B) swapped-pred A. 2141 P = CmpInst::getSwappedPredicate(Pred); 2142 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 2143 (A == RHS || B == RHS)) { 2144 if (A != RHS) std::swap(A, B); // smin(A, B) pred A. 2145 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 2146 // We analyze this as smax(-A, -B) swapped-pred -A. 2147 // Note that we do not need to actually form -A or -B thanks to EqP. 2148 P = CmpInst::getSwappedPredicate(Pred); 2149 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 2150 (A == LHS || B == LHS)) { 2151 if (A != LHS) std::swap(A, B); // A pred smin(A, B). 2152 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 2153 // We analyze this as smax(-A, -B) pred -A. 2154 // Note that we do not need to actually form -A or -B thanks to EqP. 2155 P = Pred; 2156 } 2157 if (P != CmpInst::BAD_ICMP_PREDICATE) { 2158 // Cases correspond to "max(A, B) p A". 2159 switch (P) { 2160 default: 2161 break; 2162 case CmpInst::ICMP_EQ: 2163 case CmpInst::ICMP_SLE: 2164 // Equivalent to "A EqP B". This may be the same as the condition tested 2165 // in the max/min; if so, we can just return that. 2166 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 2167 return V; 2168 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 2169 return V; 2170 // Otherwise, see if "A EqP B" simplifies. 2171 if (MaxRecurse) 2172 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1)) 2173 return V; 2174 break; 2175 case CmpInst::ICMP_NE: 2176 case CmpInst::ICMP_SGT: { 2177 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 2178 // Equivalent to "A InvEqP B". This may be the same as the condition 2179 // tested in the max/min; if so, we can just return that. 2180 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 2181 return V; 2182 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 2183 return V; 2184 // Otherwise, see if "A InvEqP B" simplifies. 2185 if (MaxRecurse) 2186 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1)) 2187 return V; 2188 break; 2189 } 2190 case CmpInst::ICMP_SGE: 2191 // Always true. 2192 return getTrue(ITy); 2193 case CmpInst::ICMP_SLT: 2194 // Always false. 2195 return getFalse(ITy); 2196 } 2197 } 2198 2199 // Unsigned variants on "max(a,b)>=a -> true". 2200 P = CmpInst::BAD_ICMP_PREDICATE; 2201 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 2202 if (A != RHS) std::swap(A, B); // umax(A, B) pred A. 2203 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 2204 // We analyze this as umax(A, B) pred A. 2205 P = Pred; 2206 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 2207 (A == LHS || B == LHS)) { 2208 if (A != LHS) std::swap(A, B); // A pred umax(A, B). 2209 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 2210 // We analyze this as umax(A, B) swapped-pred A. 2211 P = CmpInst::getSwappedPredicate(Pred); 2212 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 2213 (A == RHS || B == RHS)) { 2214 if (A != RHS) std::swap(A, B); // umin(A, B) pred A. 2215 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 2216 // We analyze this as umax(-A, -B) swapped-pred -A. 2217 // Note that we do not need to actually form -A or -B thanks to EqP. 2218 P = CmpInst::getSwappedPredicate(Pred); 2219 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 2220 (A == LHS || B == LHS)) { 2221 if (A != LHS) std::swap(A, B); // A pred umin(A, B). 2222 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 2223 // We analyze this as umax(-A, -B) pred -A. 2224 // Note that we do not need to actually form -A or -B thanks to EqP. 2225 P = Pred; 2226 } 2227 if (P != CmpInst::BAD_ICMP_PREDICATE) { 2228 // Cases correspond to "max(A, B) p A". 2229 switch (P) { 2230 default: 2231 break; 2232 case CmpInst::ICMP_EQ: 2233 case CmpInst::ICMP_ULE: 2234 // Equivalent to "A EqP B". This may be the same as the condition tested 2235 // in the max/min; if so, we can just return that. 2236 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 2237 return V; 2238 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 2239 return V; 2240 // Otherwise, see if "A EqP B" simplifies. 2241 if (MaxRecurse) 2242 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1)) 2243 return V; 2244 break; 2245 case CmpInst::ICMP_NE: 2246 case CmpInst::ICMP_UGT: { 2247 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 2248 // Equivalent to "A InvEqP B". This may be the same as the condition 2249 // tested in the max/min; if so, we can just return that. 2250 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 2251 return V; 2252 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 2253 return V; 2254 // Otherwise, see if "A InvEqP B" simplifies. 2255 if (MaxRecurse) 2256 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1)) 2257 return V; 2258 break; 2259 } 2260 case CmpInst::ICMP_UGE: 2261 // Always true. 2262 return getTrue(ITy); 2263 case CmpInst::ICMP_ULT: 2264 // Always false. 2265 return getFalse(ITy); 2266 } 2267 } 2268 2269 // Variants on "max(x,y) >= min(x,z)". 2270 Value *C, *D; 2271 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 2272 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 2273 (A == C || A == D || B == C || B == D)) { 2274 // max(x, ?) pred min(x, ?). 2275 if (Pred == CmpInst::ICMP_SGE) 2276 // Always true. 2277 return getTrue(ITy); 2278 if (Pred == CmpInst::ICMP_SLT) 2279 // Always false. 2280 return getFalse(ITy); 2281 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 2282 match(RHS, m_SMax(m_Value(C), m_Value(D))) && 2283 (A == C || A == D || B == C || B == D)) { 2284 // min(x, ?) pred max(x, ?). 2285 if (Pred == CmpInst::ICMP_SLE) 2286 // Always true. 2287 return getTrue(ITy); 2288 if (Pred == CmpInst::ICMP_SGT) 2289 // Always false. 2290 return getFalse(ITy); 2291 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 2292 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 2293 (A == C || A == D || B == C || B == D)) { 2294 // max(x, ?) pred min(x, ?). 2295 if (Pred == CmpInst::ICMP_UGE) 2296 // Always true. 2297 return getTrue(ITy); 2298 if (Pred == CmpInst::ICMP_ULT) 2299 // Always false. 2300 return getFalse(ITy); 2301 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 2302 match(RHS, m_UMax(m_Value(C), m_Value(D))) && 2303 (A == C || A == D || B == C || B == D)) { 2304 // min(x, ?) pred max(x, ?). 2305 if (Pred == CmpInst::ICMP_ULE) 2306 // Always true. 2307 return getTrue(ITy); 2308 if (Pred == CmpInst::ICMP_UGT) 2309 // Always false. 2310 return getFalse(ITy); 2311 } 2312 2313 // Simplify comparisons of GEPs. 2314 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) { 2315 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) { 2316 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() && 2317 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() && 2318 (ICmpInst::isEquality(Pred) || 2319 (GLHS->isInBounds() && GRHS->isInBounds() && 2320 Pred == ICmpInst::getSignedPredicate(Pred)))) { 2321 // The bases are equal and the indices are constant. Build a constant 2322 // expression GEP with the same indices and a null base pointer to see 2323 // what constant folding can make out of it. 2324 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType()); 2325 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end()); 2326 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS); 2327 2328 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end()); 2329 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS); 2330 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS); 2331 } 2332 } 2333 } 2334 2335 // If the comparison is with the result of a select instruction, check whether 2336 // comparing with either branch of the select always yields the same value. 2337 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2338 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 2339 return V; 2340 2341 // If the comparison is with the result of a phi instruction, check whether 2342 // doing the compare with each incoming phi value yields a common result. 2343 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2344 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 2345 return V; 2346 2347 return 0; 2348} 2349 2350Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2351 const TargetData *TD, 2352 const TargetLibraryInfo *TLI, 2353 const DominatorTree *DT) { 2354 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), 2355 RecursionLimit); 2356} 2357 2358/// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can 2359/// fold the result. If not, this returns null. 2360static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2361 const Query &Q, unsigned MaxRecurse) { 2362 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 2363 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 2364 2365 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 2366 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 2367 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI); 2368 2369 // If we have a constant, make sure it is on the RHS. 2370 std::swap(LHS, RHS); 2371 Pred = CmpInst::getSwappedPredicate(Pred); 2372 } 2373 2374 // Fold trivial predicates. 2375 if (Pred == FCmpInst::FCMP_FALSE) 2376 return ConstantInt::get(GetCompareTy(LHS), 0); 2377 if (Pred == FCmpInst::FCMP_TRUE) 2378 return ConstantInt::get(GetCompareTy(LHS), 1); 2379 2380 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef 2381 return UndefValue::get(GetCompareTy(LHS)); 2382 2383 // fcmp x,x -> true/false. Not all compares are foldable. 2384 if (LHS == RHS) { 2385 if (CmpInst::isTrueWhenEqual(Pred)) 2386 return ConstantInt::get(GetCompareTy(LHS), 1); 2387 if (CmpInst::isFalseWhenEqual(Pred)) 2388 return ConstantInt::get(GetCompareTy(LHS), 0); 2389 } 2390 2391 // Handle fcmp with constant RHS 2392 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 2393 // If the constant is a nan, see if we can fold the comparison based on it. 2394 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { 2395 if (CFP->getValueAPF().isNaN()) { 2396 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo" 2397 return ConstantInt::getFalse(CFP->getContext()); 2398 assert(FCmpInst::isUnordered(Pred) && 2399 "Comparison must be either ordered or unordered!"); 2400 // True if unordered. 2401 return ConstantInt::getTrue(CFP->getContext()); 2402 } 2403 // Check whether the constant is an infinity. 2404 if (CFP->getValueAPF().isInfinity()) { 2405 if (CFP->getValueAPF().isNegative()) { 2406 switch (Pred) { 2407 case FCmpInst::FCMP_OLT: 2408 // No value is ordered and less than negative infinity. 2409 return ConstantInt::getFalse(CFP->getContext()); 2410 case FCmpInst::FCMP_UGE: 2411 // All values are unordered with or at least negative infinity. 2412 return ConstantInt::getTrue(CFP->getContext()); 2413 default: 2414 break; 2415 } 2416 } else { 2417 switch (Pred) { 2418 case FCmpInst::FCMP_OGT: 2419 // No value is ordered and greater than infinity. 2420 return ConstantInt::getFalse(CFP->getContext()); 2421 case FCmpInst::FCMP_ULE: 2422 // All values are unordered with and at most infinity. 2423 return ConstantInt::getTrue(CFP->getContext()); 2424 default: 2425 break; 2426 } 2427 } 2428 } 2429 } 2430 } 2431 2432 // If the comparison is with the result of a select instruction, check whether 2433 // comparing with either branch of the select always yields the same value. 2434 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2435 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 2436 return V; 2437 2438 // If the comparison is with the result of a phi instruction, check whether 2439 // doing the compare with each incoming phi value yields a common result. 2440 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2441 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 2442 return V; 2443 2444 return 0; 2445} 2446 2447Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2448 const TargetData *TD, 2449 const TargetLibraryInfo *TLI, 2450 const DominatorTree *DT) { 2451 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), 2452 RecursionLimit); 2453} 2454 2455/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold 2456/// the result. If not, this returns null. 2457static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal, 2458 Value *FalseVal, const Query &Q, 2459 unsigned MaxRecurse) { 2460 // select true, X, Y -> X 2461 // select false, X, Y -> Y 2462 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal)) 2463 return CB->getZExtValue() ? TrueVal : FalseVal; 2464 2465 // select C, X, X -> X 2466 if (TrueVal == FalseVal) 2467 return TrueVal; 2468 2469 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y 2470 if (isa<Constant>(TrueVal)) 2471 return TrueVal; 2472 return FalseVal; 2473 } 2474 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X 2475 return FalseVal; 2476 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X 2477 return TrueVal; 2478 2479 return 0; 2480} 2481 2482Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 2483 const TargetData *TD, 2484 const TargetLibraryInfo *TLI, 2485 const DominatorTree *DT) { 2486 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT), 2487 RecursionLimit); 2488} 2489 2490/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can 2491/// fold the result. If not, this returns null. 2492static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) { 2493 // The type of the GEP pointer operand. 2494 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType()); 2495 // The GEP pointer operand is not a pointer, it's a vector of pointers. 2496 if (!PtrTy) 2497 return 0; 2498 2499 // getelementptr P -> P. 2500 if (Ops.size() == 1) 2501 return Ops[0]; 2502 2503 if (isa<UndefValue>(Ops[0])) { 2504 // Compute the (pointer) type returned by the GEP instruction. 2505 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1)); 2506 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace()); 2507 return UndefValue::get(GEPTy); 2508 } 2509 2510 if (Ops.size() == 2) { 2511 // getelementptr P, 0 -> P. 2512 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1])) 2513 if (C->isZero()) 2514 return Ops[0]; 2515 // getelementptr P, N -> P if P points to a type of zero size. 2516 if (Q.TD) { 2517 Type *Ty = PtrTy->getElementType(); 2518 if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0) 2519 return Ops[0]; 2520 } 2521 } 2522 2523 // Check to see if this is constant foldable. 2524 for (unsigned i = 0, e = Ops.size(); i != e; ++i) 2525 if (!isa<Constant>(Ops[i])) 2526 return 0; 2527 2528 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1)); 2529} 2530 2531Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const TargetData *TD, 2532 const TargetLibraryInfo *TLI, 2533 const DominatorTree *DT) { 2534 return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit); 2535} 2536 2537/// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we 2538/// can fold the result. If not, this returns null. 2539static Value *SimplifyInsertValueInst(Value *Agg, Value *Val, 2540 ArrayRef<unsigned> Idxs, const Query &Q, 2541 unsigned) { 2542 if (Constant *CAgg = dyn_cast<Constant>(Agg)) 2543 if (Constant *CVal = dyn_cast<Constant>(Val)) 2544 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); 2545 2546 // insertvalue x, undef, n -> x 2547 if (match(Val, m_Undef())) 2548 return Agg; 2549 2550 // insertvalue x, (extractvalue y, n), n 2551 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) 2552 if (EV->getAggregateOperand()->getType() == Agg->getType() && 2553 EV->getIndices() == Idxs) { 2554 // insertvalue undef, (extractvalue y, n), n -> y 2555 if (match(Agg, m_Undef())) 2556 return EV->getAggregateOperand(); 2557 2558 // insertvalue y, (extractvalue y, n), n -> y 2559 if (Agg == EV->getAggregateOperand()) 2560 return Agg; 2561 } 2562 2563 return 0; 2564} 2565 2566Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val, 2567 ArrayRef<unsigned> Idxs, 2568 const TargetData *TD, 2569 const TargetLibraryInfo *TLI, 2570 const DominatorTree *DT) { 2571 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT), 2572 RecursionLimit); 2573} 2574 2575/// SimplifyPHINode - See if we can fold the given phi. If not, returns null. 2576static Value *SimplifyPHINode(PHINode *PN, const Query &Q) { 2577 // If all of the PHI's incoming values are the same then replace the PHI node 2578 // with the common value. 2579 Value *CommonValue = 0; 2580 bool HasUndefInput = false; 2581 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 2582 Value *Incoming = PN->getIncomingValue(i); 2583 // If the incoming value is the phi node itself, it can safely be skipped. 2584 if (Incoming == PN) continue; 2585 if (isa<UndefValue>(Incoming)) { 2586 // Remember that we saw an undef value, but otherwise ignore them. 2587 HasUndefInput = true; 2588 continue; 2589 } 2590 if (CommonValue && Incoming != CommonValue) 2591 return 0; // Not the same, bail out. 2592 CommonValue = Incoming; 2593 } 2594 2595 // If CommonValue is null then all of the incoming values were either undef or 2596 // equal to the phi node itself. 2597 if (!CommonValue) 2598 return UndefValue::get(PN->getType()); 2599 2600 // If we have a PHI node like phi(X, undef, X), where X is defined by some 2601 // instruction, we cannot return X as the result of the PHI node unless it 2602 // dominates the PHI block. 2603 if (HasUndefInput) 2604 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : 0; 2605 2606 return CommonValue; 2607} 2608 2609static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) { 2610 if (Constant *C = dyn_cast<Constant>(Op)) 2611 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.TD, Q.TLI); 2612 2613 return 0; 2614} 2615 2616Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const TargetData *TD, 2617 const TargetLibraryInfo *TLI, 2618 const DominatorTree *DT) { 2619 return ::SimplifyTruncInst(Op, Ty, Query (TD, TLI, DT), RecursionLimit); 2620} 2621 2622//=== Helper functions for higher up the class hierarchy. 2623 2624/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can 2625/// fold the result. If not, this returns null. 2626static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 2627 const Query &Q, unsigned MaxRecurse) { 2628 switch (Opcode) { 2629 case Instruction::Add: 2630 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2631 Q, MaxRecurse); 2632 case Instruction::Sub: 2633 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2634 Q, MaxRecurse); 2635 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse); 2636 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse); 2637 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse); 2638 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse); 2639 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse); 2640 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse); 2641 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse); 2642 case Instruction::Shl: 2643 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2644 Q, MaxRecurse); 2645 case Instruction::LShr: 2646 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse); 2647 case Instruction::AShr: 2648 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse); 2649 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse); 2650 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse); 2651 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse); 2652 default: 2653 if (Constant *CLHS = dyn_cast<Constant>(LHS)) 2654 if (Constant *CRHS = dyn_cast<Constant>(RHS)) { 2655 Constant *COps[] = {CLHS, CRHS}; 2656 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.TD, 2657 Q.TLI); 2658 } 2659 2660 // If the operation is associative, try some generic simplifications. 2661 if (Instruction::isAssociative(Opcode)) 2662 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse)) 2663 return V; 2664 2665 // If the operation is with the result of a select instruction check whether 2666 // operating on either branch of the select always yields the same value. 2667 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2668 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse)) 2669 return V; 2670 2671 // If the operation is with the result of a phi instruction, check whether 2672 // operating on all incoming values of the phi always yields the same value. 2673 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2674 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse)) 2675 return V; 2676 2677 return 0; 2678 } 2679} 2680 2681Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 2682 const TargetData *TD, const TargetLibraryInfo *TLI, 2683 const DominatorTree *DT) { 2684 return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, DT), RecursionLimit); 2685} 2686 2687/// SimplifyCmpInst - Given operands for a CmpInst, see if we can 2688/// fold the result. 2689static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2690 const Query &Q, unsigned MaxRecurse) { 2691 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 2692 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 2693 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 2694} 2695 2696Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2697 const TargetData *TD, const TargetLibraryInfo *TLI, 2698 const DominatorTree *DT) { 2699 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), 2700 RecursionLimit); 2701} 2702 2703static Value *SimplifyCallInst(CallInst *CI, const Query &) { 2704 // call undef -> undef 2705 if (isa<UndefValue>(CI->getCalledValue())) 2706 return UndefValue::get(CI->getType()); 2707 2708 return 0; 2709} 2710 2711/// SimplifyInstruction - See if we can compute a simplified version of this 2712/// instruction. If not, this returns null. 2713Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD, 2714 const TargetLibraryInfo *TLI, 2715 const DominatorTree *DT) { 2716 Value *Result; 2717 2718 switch (I->getOpcode()) { 2719 default: 2720 Result = ConstantFoldInstruction(I, TD, TLI); 2721 break; 2722 case Instruction::Add: 2723 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1), 2724 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2725 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2726 TD, TLI, DT); 2727 break; 2728 case Instruction::Sub: 2729 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1), 2730 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2731 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2732 TD, TLI, DT); 2733 break; 2734 case Instruction::Mul: 2735 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2736 break; 2737 case Instruction::SDiv: 2738 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2739 break; 2740 case Instruction::UDiv: 2741 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2742 break; 2743 case Instruction::FDiv: 2744 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2745 break; 2746 case Instruction::SRem: 2747 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2748 break; 2749 case Instruction::URem: 2750 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2751 break; 2752 case Instruction::FRem: 2753 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2754 break; 2755 case Instruction::Shl: 2756 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), 2757 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2758 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2759 TD, TLI, DT); 2760 break; 2761 case Instruction::LShr: 2762 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), 2763 cast<BinaryOperator>(I)->isExact(), 2764 TD, TLI, DT); 2765 break; 2766 case Instruction::AShr: 2767 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), 2768 cast<BinaryOperator>(I)->isExact(), 2769 TD, TLI, DT); 2770 break; 2771 case Instruction::And: 2772 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2773 break; 2774 case Instruction::Or: 2775 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2776 break; 2777 case Instruction::Xor: 2778 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2779 break; 2780 case Instruction::ICmp: 2781 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), 2782 I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2783 break; 2784 case Instruction::FCmp: 2785 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), 2786 I->getOperand(0), I->getOperand(1), TD, TLI, DT); 2787 break; 2788 case Instruction::Select: 2789 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), 2790 I->getOperand(2), TD, TLI, DT); 2791 break; 2792 case Instruction::GetElementPtr: { 2793 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end()); 2794 Result = SimplifyGEPInst(Ops, TD, TLI, DT); 2795 break; 2796 } 2797 case Instruction::InsertValue: { 2798 InsertValueInst *IV = cast<InsertValueInst>(I); 2799 Result = SimplifyInsertValueInst(IV->getAggregateOperand(), 2800 IV->getInsertedValueOperand(), 2801 IV->getIndices(), TD, TLI, DT); 2802 break; 2803 } 2804 case Instruction::PHI: 2805 Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT)); 2806 break; 2807 case Instruction::Call: 2808 Result = SimplifyCallInst(cast<CallInst>(I), Query (TD, TLI, DT)); 2809 break; 2810 case Instruction::Trunc: 2811 Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, DT); 2812 break; 2813 } 2814 2815 /// If called on unreachable code, the above logic may report that the 2816 /// instruction simplified to itself. Make life easier for users by 2817 /// detecting that case here, returning a safe value instead. 2818 return Result == I ? UndefValue::get(I->getType()) : Result; 2819} 2820 2821/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then 2822/// delete the From instruction. In addition to a basic RAUW, this does a 2823/// recursive simplification of the newly formed instructions. This catches 2824/// things where one simplification exposes other opportunities. This only 2825/// simplifies and deletes scalar operations, it does not change the CFG. 2826/// 2827void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To, 2828 const TargetData *TD, 2829 const TargetLibraryInfo *TLI, 2830 const DominatorTree *DT) { 2831 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!"); 2832 2833 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that 2834 // we can know if it gets deleted out from under us or replaced in a 2835 // recursive simplification. 2836 WeakVH FromHandle(From); 2837 WeakVH ToHandle(To); 2838 2839 while (!From->use_empty()) { 2840 // Update the instruction to use the new value. 2841 Use &TheUse = From->use_begin().getUse(); 2842 Instruction *User = cast<Instruction>(TheUse.getUser()); 2843 TheUse = To; 2844 2845 // Check to see if the instruction can be folded due to the operand 2846 // replacement. For example changing (or X, Y) into (or X, -1) can replace 2847 // the 'or' with -1. 2848 Value *SimplifiedVal; 2849 { 2850 // Sanity check to make sure 'User' doesn't dangle across 2851 // SimplifyInstruction. 2852 AssertingVH<> UserHandle(User); 2853 2854 SimplifiedVal = SimplifyInstruction(User, TD, TLI, DT); 2855 if (SimplifiedVal == 0) continue; 2856 } 2857 2858 // Recursively simplify this user to the new value. 2859 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, TLI, DT); 2860 From = dyn_cast_or_null<Instruction>((Value*)FromHandle); 2861 To = ToHandle; 2862 2863 assert(ToHandle && "To value deleted by recursive simplification?"); 2864 2865 // If the recursive simplification ended up revisiting and deleting 2866 // 'From' then we're done. 2867 if (From == 0) 2868 return; 2869 } 2870 2871 // If 'From' has value handles referring to it, do a real RAUW to update them. 2872 From->replaceAllUsesWith(To); 2873 2874 From->eraseFromParent(); 2875} 2876