ConstantFold.cpp revision 43ad6b3e0d6ada51e9b23aab3e061187f1f5710c
1//===- ConstantFold.cpp - LLVM constant folder ----------------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements folding of constants for LLVM. This implements the 11// (internal) ConstantFold.h interface, which is used by the 12// ConstantExpr::get* methods to automatically fold constants when possible. 13// 14// The current constant folding implementation is implemented in two pieces: the 15// template-based folder for simple primitive constants like ConstantInt, and 16// the special case hackery that we use to symbolically evaluate expressions 17// that use ConstantExprs. 18// 19//===----------------------------------------------------------------------===// 20 21#include "ConstantFold.h" 22#include "llvm/Constants.h" 23#include "llvm/Instructions.h" 24#include "llvm/DerivedTypes.h" 25#include "llvm/Function.h" 26#include "llvm/GlobalAlias.h" 27#include "llvm/ADT/SmallVector.h" 28#include "llvm/Support/Compiler.h" 29#include "llvm/Support/GetElementPtrTypeIterator.h" 30#include "llvm/Support/ManagedStatic.h" 31#include "llvm/Support/MathExtras.h" 32#include <limits> 33using namespace llvm; 34 35//===----------------------------------------------------------------------===// 36// ConstantFold*Instruction Implementations 37//===----------------------------------------------------------------------===// 38 39/// BitCastConstantVector - Convert the specified ConstantVector node to the 40/// specified vector type. At this point, we know that the elements of the 41/// input vector constant are all simple integer or FP values. 42static Constant *BitCastConstantVector(ConstantVector *CV, 43 const VectorType *DstTy) { 44 // If this cast changes element count then we can't handle it here: 45 // doing so requires endianness information. This should be handled by 46 // Analysis/ConstantFolding.cpp 47 unsigned NumElts = DstTy->getNumElements(); 48 if (NumElts != CV->getNumOperands()) 49 return 0; 50 51 // Check to verify that all elements of the input are simple. 52 for (unsigned i = 0; i != NumElts; ++i) { 53 if (!isa<ConstantInt>(CV->getOperand(i)) && 54 !isa<ConstantFP>(CV->getOperand(i))) 55 return 0; 56 } 57 58 // Bitcast each element now. 59 std::vector<Constant*> Result; 60 const Type *DstEltTy = DstTy->getElementType(); 61 for (unsigned i = 0; i != NumElts; ++i) 62 Result.push_back(ConstantExpr::getBitCast(CV->getOperand(i), DstEltTy)); 63 return ConstantVector::get(Result); 64} 65 66/// This function determines which opcode to use to fold two constant cast 67/// expressions together. It uses CastInst::isEliminableCastPair to determine 68/// the opcode. Consequently its just a wrapper around that function. 69/// @brief Determine if it is valid to fold a cast of a cast 70static unsigned 71foldConstantCastPair( 72 unsigned opc, ///< opcode of the second cast constant expression 73 const ConstantExpr*Op, ///< the first cast constant expression 74 const Type *DstTy ///< desintation type of the first cast 75) { 76 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!"); 77 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type"); 78 assert(CastInst::isCast(opc) && "Invalid cast opcode"); 79 80 // The the types and opcodes for the two Cast constant expressions 81 const Type *SrcTy = Op->getOperand(0)->getType(); 82 const Type *MidTy = Op->getType(); 83 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode()); 84 Instruction::CastOps secondOp = Instruction::CastOps(opc); 85 86 // Let CastInst::isEliminableCastPair do the heavy lifting. 87 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy, 88 Type::Int64Ty); 89} 90 91static Constant *FoldBitCast(Constant *V, const Type *DestTy) { 92 const Type *SrcTy = V->getType(); 93 if (SrcTy == DestTy) 94 return V; // no-op cast 95 96 // Check to see if we are casting a pointer to an aggregate to a pointer to 97 // the first element. If so, return the appropriate GEP instruction. 98 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) 99 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) { 100 SmallVector<Value*, 8> IdxList; 101 IdxList.push_back(Constant::getNullValue(Type::Int32Ty)); 102 const Type *ElTy = PTy->getElementType(); 103 while (ElTy != DPTy->getElementType()) { 104 if (const StructType *STy = dyn_cast<StructType>(ElTy)) { 105 if (STy->getNumElements() == 0) break; 106 ElTy = STy->getElementType(0); 107 IdxList.push_back(Constant::getNullValue(Type::Int32Ty)); 108 } else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) { 109 if (isa<PointerType>(ElTy)) break; // Can't index into pointers! 110 ElTy = STy->getElementType(); 111 IdxList.push_back(IdxList[0]); 112 } else { 113 break; 114 } 115 } 116 117 if (ElTy == DPTy->getElementType()) 118 return ConstantExpr::getGetElementPtr(V, &IdxList[0], IdxList.size()); 119 } 120 121 // Handle casts from one vector constant to another. We know that the src 122 // and dest type have the same size (otherwise its an illegal cast). 123 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { 124 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { 125 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && 126 "Not cast between same sized vectors!"); 127 // First, check for null. Undef is already handled. 128 if (isa<ConstantAggregateZero>(V)) 129 return Constant::getNullValue(DestTy); 130 131 if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) 132 return BitCastConstantVector(CV, DestPTy); 133 } 134 } 135 136 // Finally, implement bitcast folding now. The code below doesn't handle 137 // bitcast right. 138 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. 139 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 140 141 // Handle integral constant input. 142 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 143 if (DestTy->isInteger()) 144 // Integral -> Integral. This is a no-op because the bit widths must 145 // be the same. Consequently, we just fold to V. 146 return V; 147 148 if (DestTy->isFloatingPoint()) { 149 assert((DestTy == Type::DoubleTy || DestTy == Type::FloatTy) && 150 "Unknown FP type!"); 151 return ConstantFP::get(DestTy, APFloat(CI->getValue())); 152 } 153 // Otherwise, can't fold this (vector?) 154 return 0; 155 } 156 157 // Handle ConstantFP input. 158 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) { 159 // FP -> Integral. 160 if (DestTy == Type::Int32Ty) { 161 return ConstantInt::get(FP->getValueAPF().convertToAPInt()); 162 } else { 163 assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!"); 164 return ConstantInt::get(FP->getValueAPF().convertToAPInt()); 165 } 166 } 167 return 0; 168} 169 170 171Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V, 172 const Type *DestTy) { 173 const Type *SrcTy = V->getType(); 174 175 if (isa<UndefValue>(V)) { 176 // zext(undef) = 0, because the top bits will be zero. 177 // sext(undef) = 0, because the top bits will all be the same. 178 if (opc == Instruction::ZExt || opc == Instruction::SExt) 179 return Constant::getNullValue(DestTy); 180 return UndefValue::get(DestTy); 181 } 182 // No compile-time operations on this type yet. 183 if (V->getType() == Type::PPC_FP128Ty || DestTy == Type::PPC_FP128Ty) 184 return 0; 185 186 // If the cast operand is a constant expression, there's a few things we can 187 // do to try to simplify it. 188 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 189 if (CE->isCast()) { 190 // Try hard to fold cast of cast because they are often eliminable. 191 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) 192 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); 193 } else if (CE->getOpcode() == Instruction::GetElementPtr) { 194 // If all of the indexes in the GEP are null values, there is no pointer 195 // adjustment going on. We might as well cast the source pointer. 196 bool isAllNull = true; 197 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) 198 if (!CE->getOperand(i)->isNullValue()) { 199 isAllNull = false; 200 break; 201 } 202 if (isAllNull) 203 // This is casting one pointer type to another, always BitCast 204 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); 205 } 206 } 207 208 // We actually have to do a cast now. Perform the cast according to the 209 // opcode specified. 210 switch (opc) { 211 case Instruction::FPTrunc: 212 case Instruction::FPExt: 213 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 214 APFloat Val = FPC->getValueAPF(); 215 Val.convert(DestTy == Type::FloatTy ? APFloat::IEEEsingle : 216 DestTy == Type::DoubleTy ? APFloat::IEEEdouble : 217 DestTy == Type::X86_FP80Ty ? APFloat::x87DoubleExtended : 218 DestTy == Type::FP128Ty ? APFloat::IEEEquad : 219 APFloat::Bogus, 220 APFloat::rmNearestTiesToEven); 221 return ConstantFP::get(DestTy, Val); 222 } 223 return 0; // Can't fold. 224 case Instruction::FPToUI: 225 case Instruction::FPToSI: 226 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 227 const APFloat &V = FPC->getValueAPF(); 228 uint64_t x[2]; 229 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 230 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, 231 APFloat::rmTowardZero); 232 APInt Val(DestBitWidth, 2, x); 233 return ConstantInt::get(Val); 234 } 235 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) { 236 std::vector<Constant*> res; 237 const VectorType *DestVecTy = cast<VectorType>(DestTy); 238 const Type *DstEltTy = DestVecTy->getElementType(); 239 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) 240 res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i), 241 DstEltTy)); 242 return ConstantVector::get(DestVecTy, res); 243 } 244 return 0; // Can't fold. 245 case Instruction::IntToPtr: //always treated as unsigned 246 if (V->isNullValue()) // Is it an integral null value? 247 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 248 return 0; // Other pointer types cannot be casted 249 case Instruction::PtrToInt: // always treated as unsigned 250 if (V->isNullValue()) // is it a null pointer value? 251 return ConstantInt::get(DestTy, 0); 252 return 0; // Other pointer types cannot be casted 253 case Instruction::UIToFP: 254 case Instruction::SIToFP: 255 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 256 APInt api = CI->getValue(); 257 const uint64_t zero[] = {0, 0}; 258 uint32_t BitWidth = cast<IntegerType>(SrcTy)->getBitWidth(); 259 APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(), 260 2, zero)); 261 (void)apf.convertFromZeroExtendedInteger(api.getRawData(), BitWidth, 262 opc==Instruction::SIToFP, 263 APFloat::rmNearestTiesToEven); 264 return ConstantFP::get(DestTy, apf); 265 } 266 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) { 267 std::vector<Constant*> res; 268 const VectorType *DestVecTy = cast<VectorType>(DestTy); 269 const Type *DstEltTy = DestVecTy->getElementType(); 270 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) 271 res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i), 272 DstEltTy)); 273 return ConstantVector::get(DestVecTy, res); 274 } 275 return 0; 276 case Instruction::ZExt: 277 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 278 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 279 APInt Result(CI->getValue()); 280 Result.zext(BitWidth); 281 return ConstantInt::get(Result); 282 } 283 return 0; 284 case Instruction::SExt: 285 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 286 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 287 APInt Result(CI->getValue()); 288 Result.sext(BitWidth); 289 return ConstantInt::get(Result); 290 } 291 return 0; 292 case Instruction::Trunc: 293 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 294 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 295 APInt Result(CI->getValue()); 296 Result.trunc(BitWidth); 297 return ConstantInt::get(Result); 298 } 299 return 0; 300 case Instruction::BitCast: 301 return FoldBitCast(const_cast<Constant*>(V), DestTy); 302 default: 303 assert(!"Invalid CE CastInst opcode"); 304 break; 305 } 306 307 assert(0 && "Failed to cast constant expression"); 308 return 0; 309} 310 311Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond, 312 const Constant *V1, 313 const Constant *V2) { 314 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond)) 315 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2); 316 317 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2); 318 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1); 319 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1); 320 if (V1 == V2) return const_cast<Constant*>(V1); 321 return 0; 322} 323 324Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val, 325 const Constant *Idx) { 326 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef 327 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType()); 328 if (Val->isNullValue()) // ee(zero, x) -> zero 329 return Constant::getNullValue( 330 cast<VectorType>(Val->getType())->getElementType()); 331 332 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { 333 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { 334 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue())); 335 } else if (isa<UndefValue>(Idx)) { 336 // ee({w,x,y,z}, undef) -> w (an arbitrary value). 337 return const_cast<Constant*>(CVal->getOperand(0)); 338 } 339 } 340 return 0; 341} 342 343Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val, 344 const Constant *Elt, 345 const Constant *Idx) { 346 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); 347 if (!CIdx) return 0; 348 APInt idxVal = CIdx->getValue(); 349 if (isa<UndefValue>(Val)) { 350 // Insertion of scalar constant into vector undef 351 // Optimize away insertion of undef 352 if (isa<UndefValue>(Elt)) 353 return const_cast<Constant*>(Val); 354 // Otherwise break the aggregate undef into multiple undefs and do 355 // the insertion 356 unsigned numOps = 357 cast<VectorType>(Val->getType())->getNumElements(); 358 std::vector<Constant*> Ops; 359 Ops.reserve(numOps); 360 for (unsigned i = 0; i < numOps; ++i) { 361 const Constant *Op = 362 (idxVal == i) ? Elt : UndefValue::get(Elt->getType()); 363 Ops.push_back(const_cast<Constant*>(Op)); 364 } 365 return ConstantVector::get(Ops); 366 } 367 if (isa<ConstantAggregateZero>(Val)) { 368 // Insertion of scalar constant into vector aggregate zero 369 // Optimize away insertion of zero 370 if (Elt->isNullValue()) 371 return const_cast<Constant*>(Val); 372 // Otherwise break the aggregate zero into multiple zeros and do 373 // the insertion 374 unsigned numOps = 375 cast<VectorType>(Val->getType())->getNumElements(); 376 std::vector<Constant*> Ops; 377 Ops.reserve(numOps); 378 for (unsigned i = 0; i < numOps; ++i) { 379 const Constant *Op = 380 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType()); 381 Ops.push_back(const_cast<Constant*>(Op)); 382 } 383 return ConstantVector::get(Ops); 384 } 385 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { 386 // Insertion of scalar constant into vector constant 387 std::vector<Constant*> Ops; 388 Ops.reserve(CVal->getNumOperands()); 389 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) { 390 const Constant *Op = 391 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i)); 392 Ops.push_back(const_cast<Constant*>(Op)); 393 } 394 return ConstantVector::get(Ops); 395 } 396 return 0; 397} 398 399/// GetVectorElement - If C is a ConstantVector, ConstantAggregateZero or Undef 400/// return the specified element value. Otherwise return null. 401static Constant *GetVectorElement(const Constant *C, unsigned EltNo) { 402 if (const ConstantVector *CV = dyn_cast<ConstantVector>(C)) 403 return const_cast<Constant*>(CV->getOperand(EltNo)); 404 405 const Type *EltTy = cast<VectorType>(C->getType())->getElementType(); 406 if (isa<ConstantAggregateZero>(C)) 407 return Constant::getNullValue(EltTy); 408 if (isa<UndefValue>(C)) 409 return UndefValue::get(EltTy); 410 return 0; 411} 412 413Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1, 414 const Constant *V2, 415 const Constant *Mask) { 416 // Undefined shuffle mask -> undefined value. 417 if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType()); 418 419 unsigned NumElts = cast<VectorType>(V1->getType())->getNumElements(); 420 const Type *EltTy = cast<VectorType>(V1->getType())->getElementType(); 421 422 // Loop over the shuffle mask, evaluating each element. 423 SmallVector<Constant*, 32> Result; 424 for (unsigned i = 0; i != NumElts; ++i) { 425 Constant *InElt = GetVectorElement(Mask, i); 426 if (InElt == 0) return 0; 427 428 if (isa<UndefValue>(InElt)) 429 InElt = UndefValue::get(EltTy); 430 else if (ConstantInt *CI = dyn_cast<ConstantInt>(InElt)) { 431 unsigned Elt = CI->getZExtValue(); 432 if (Elt >= NumElts*2) 433 InElt = UndefValue::get(EltTy); 434 else if (Elt >= NumElts) 435 InElt = GetVectorElement(V2, Elt-NumElts); 436 else 437 InElt = GetVectorElement(V1, Elt); 438 if (InElt == 0) return 0; 439 } else { 440 // Unknown value. 441 return 0; 442 } 443 Result.push_back(InElt); 444 } 445 446 return ConstantVector::get(&Result[0], Result.size()); 447} 448 449/// EvalVectorOp - Given two vector constants and a function pointer, apply the 450/// function pointer to each element pair, producing a new ConstantVector 451/// constant. Either or both of V1 and V2 may be NULL, meaning a 452/// ConstantAggregateZero operand. 453static Constant *EvalVectorOp(const ConstantVector *V1, 454 const ConstantVector *V2, 455 const VectorType *VTy, 456 Constant *(*FP)(Constant*, Constant*)) { 457 std::vector<Constant*> Res; 458 const Type *EltTy = VTy->getElementType(); 459 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 460 const Constant *C1 = V1 ? V1->getOperand(i) : Constant::getNullValue(EltTy); 461 const Constant *C2 = V2 ? V2->getOperand(i) : Constant::getNullValue(EltTy); 462 Res.push_back(FP(const_cast<Constant*>(C1), 463 const_cast<Constant*>(C2))); 464 } 465 return ConstantVector::get(Res); 466} 467 468Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, 469 const Constant *C1, 470 const Constant *C2) { 471 // No compile-time operations on this type yet. 472 if (C1->getType() == Type::PPC_FP128Ty) 473 return 0; 474 475 // Handle UndefValue up front 476 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 477 switch (Opcode) { 478 case Instruction::Add: 479 case Instruction::Sub: 480 case Instruction::Xor: 481 return UndefValue::get(C1->getType()); 482 case Instruction::Mul: 483 case Instruction::And: 484 return Constant::getNullValue(C1->getType()); 485 case Instruction::UDiv: 486 case Instruction::SDiv: 487 case Instruction::FDiv: 488 case Instruction::URem: 489 case Instruction::SRem: 490 case Instruction::FRem: 491 if (!isa<UndefValue>(C2)) // undef / X -> 0 492 return Constant::getNullValue(C1->getType()); 493 return const_cast<Constant*>(C2); // X / undef -> undef 494 case Instruction::Or: // X | undef -> -1 495 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType())) 496 return ConstantVector::getAllOnesValue(PTy); 497 return ConstantInt::getAllOnesValue(C1->getType()); 498 case Instruction::LShr: 499 if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) 500 return const_cast<Constant*>(C1); // undef lshr undef -> undef 501 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 502 // undef lshr X -> 0 503 case Instruction::AShr: 504 if (!isa<UndefValue>(C2)) 505 return const_cast<Constant*>(C1); // undef ashr X --> undef 506 else if (isa<UndefValue>(C1)) 507 return const_cast<Constant*>(C1); // undef ashr undef -> undef 508 else 509 return const_cast<Constant*>(C1); // X ashr undef --> X 510 case Instruction::Shl: 511 // undef << X -> 0 or X << undef -> 0 512 return Constant::getNullValue(C1->getType()); 513 } 514 } 515 516 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 517 if (isa<ConstantExpr>(C2)) { 518 // There are many possible foldings we could do here. We should probably 519 // at least fold add of a pointer with an integer into the appropriate 520 // getelementptr. This will improve alias analysis a bit. 521 } else { 522 // Just implement a couple of simple identities. 523 switch (Opcode) { 524 case Instruction::Add: 525 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X + 0 == X 526 break; 527 case Instruction::Sub: 528 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X - 0 == X 529 break; 530 case Instruction::Mul: 531 if (C2->isNullValue()) return const_cast<Constant*>(C2); // X * 0 == 0 532 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) 533 if (CI->equalsInt(1)) 534 return const_cast<Constant*>(C1); // X * 1 == X 535 break; 536 case Instruction::UDiv: 537 case Instruction::SDiv: 538 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) 539 if (CI->equalsInt(1)) 540 return const_cast<Constant*>(C1); // X / 1 == X 541 break; 542 case Instruction::URem: 543 case Instruction::SRem: 544 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) 545 if (CI->equalsInt(1)) 546 return Constant::getNullValue(CI->getType()); // X % 1 == 0 547 break; 548 case Instruction::And: 549 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) { 550 if (CI->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0 551 if (CI->isAllOnesValue()) 552 return const_cast<Constant*>(C1); // X & -1 == X 553 554 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) 555 if (CE1->getOpcode() == Instruction::ZExt) { 556 APInt PossiblySetBits 557 = cast<IntegerType>(CE1->getOperand(0)->getType())->getMask(); 558 PossiblySetBits.zext(C1->getType()->getPrimitiveSizeInBits()); 559 if ((PossiblySetBits & CI->getValue()) == PossiblySetBits) 560 return const_cast<Constant*>(C1); 561 } 562 } 563 if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) { 564 GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0)); 565 566 // Functions are at least 4-byte aligned. If and'ing the address of a 567 // function with a constant < 4, fold it to zero. 568 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) 569 if (CI->getValue().ult(APInt(CI->getType()->getBitWidth(),4)) && 570 isa<Function>(CPR)) 571 return Constant::getNullValue(CI->getType()); 572 } 573 break; 574 case Instruction::Or: 575 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X | 0 == X 576 if (const ConstantInt *CI = dyn_cast<ConstantInt>(C2)) 577 if (CI->isAllOnesValue()) 578 return const_cast<Constant*>(C2); // X | -1 == -1 579 break; 580 case Instruction::Xor: 581 if (C2->isNullValue()) return const_cast<Constant*>(C1); // X ^ 0 == X 582 break; 583 case Instruction::AShr: 584 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 585 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. 586 return ConstantExpr::getLShr(const_cast<Constant*>(C1), 587 const_cast<Constant*>(C2)); 588 break; 589 } 590 } 591 } else if (isa<ConstantExpr>(C2)) { 592 // If C2 is a constant expr and C1 isn't, flop them around and fold the 593 // other way if possible. 594 switch (Opcode) { 595 case Instruction::Add: 596 case Instruction::Mul: 597 case Instruction::And: 598 case Instruction::Or: 599 case Instruction::Xor: 600 // No change of opcode required. 601 return ConstantFoldBinaryInstruction(Opcode, C2, C1); 602 603 case Instruction::Shl: 604 case Instruction::LShr: 605 case Instruction::AShr: 606 case Instruction::Sub: 607 case Instruction::SDiv: 608 case Instruction::UDiv: 609 case Instruction::FDiv: 610 case Instruction::URem: 611 case Instruction::SRem: 612 case Instruction::FRem: 613 default: // These instructions cannot be flopped around. 614 return 0; 615 } 616 } 617 618 // At this point we know neither constant is an UndefValue nor a ConstantExpr 619 // so look at directly computing the value. 620 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { 621 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 622 using namespace APIntOps; 623 APInt C1V = CI1->getValue(); 624 APInt C2V = CI2->getValue(); 625 switch (Opcode) { 626 default: 627 break; 628 case Instruction::Add: 629 return ConstantInt::get(C1V + C2V); 630 case Instruction::Sub: 631 return ConstantInt::get(C1V - C2V); 632 case Instruction::Mul: 633 return ConstantInt::get(C1V * C2V); 634 case Instruction::UDiv: 635 if (CI2->isNullValue()) 636 return 0; // X / 0 -> can't fold 637 return ConstantInt::get(C1V.udiv(C2V)); 638 case Instruction::SDiv: 639 if (CI2->isNullValue()) 640 return 0; // X / 0 -> can't fold 641 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 642 return 0; // MIN_INT / -1 -> overflow 643 return ConstantInt::get(C1V.sdiv(C2V)); 644 case Instruction::URem: 645 if (C2->isNullValue()) 646 return 0; // X / 0 -> can't fold 647 return ConstantInt::get(C1V.urem(C2V)); 648 case Instruction::SRem: 649 if (CI2->isNullValue()) 650 return 0; // X % 0 -> can't fold 651 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 652 return 0; // MIN_INT % -1 -> overflow 653 return ConstantInt::get(C1V.srem(C2V)); 654 case Instruction::And: 655 return ConstantInt::get(C1V & C2V); 656 case Instruction::Or: 657 return ConstantInt::get(C1V | C2V); 658 case Instruction::Xor: 659 return ConstantInt::get(C1V ^ C2V); 660 case Instruction::Shl: 661 if (uint32_t shiftAmt = C2V.getZExtValue()) 662 if (shiftAmt < C1V.getBitWidth()) 663 return ConstantInt::get(C1V.shl(shiftAmt)); 664 else 665 return UndefValue::get(C1->getType()); // too big shift is undef 666 return const_cast<ConstantInt*>(CI1); // Zero shift is identity 667 case Instruction::LShr: 668 if (uint32_t shiftAmt = C2V.getZExtValue()) 669 if (shiftAmt < C1V.getBitWidth()) 670 return ConstantInt::get(C1V.lshr(shiftAmt)); 671 else 672 return UndefValue::get(C1->getType()); // too big shift is undef 673 return const_cast<ConstantInt*>(CI1); // Zero shift is identity 674 case Instruction::AShr: 675 if (uint32_t shiftAmt = C2V.getZExtValue()) 676 if (shiftAmt < C1V.getBitWidth()) 677 return ConstantInt::get(C1V.ashr(shiftAmt)); 678 else 679 return UndefValue::get(C1->getType()); // too big shift is undef 680 return const_cast<ConstantInt*>(CI1); // Zero shift is identity 681 } 682 } 683 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { 684 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { 685 APFloat C1V = CFP1->getValueAPF(); 686 APFloat C2V = CFP2->getValueAPF(); 687 APFloat C3V = C1V; // copy for modification 688 bool isDouble = CFP1->getType()==Type::DoubleTy; 689 switch (Opcode) { 690 default: 691 break; 692 case Instruction::Add: 693 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); 694 return ConstantFP::get(CFP1->getType(), C3V); 695 case Instruction::Sub: 696 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); 697 return ConstantFP::get(CFP1->getType(), C3V); 698 case Instruction::Mul: 699 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); 700 return ConstantFP::get(CFP1->getType(), C3V); 701 case Instruction::FDiv: 702 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); 703 return ConstantFP::get(CFP1->getType(), C3V); 704 case Instruction::FRem: 705 if (C2V.isZero()) 706 // IEEE 754, Section 7.1, #5 707 return ConstantFP::get(CFP1->getType(), isDouble ? 708 APFloat(std::numeric_limits<double>::quiet_NaN()) : 709 APFloat(std::numeric_limits<float>::quiet_NaN())); 710 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven); 711 return ConstantFP::get(CFP1->getType(), C3V); 712 } 713 } 714 } else if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { 715 const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1); 716 const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2); 717 if ((CP1 != NULL || isa<ConstantAggregateZero>(C1)) && 718 (CP2 != NULL || isa<ConstantAggregateZero>(C2))) { 719 switch (Opcode) { 720 default: 721 break; 722 case Instruction::Add: 723 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAdd); 724 case Instruction::Sub: 725 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSub); 726 case Instruction::Mul: 727 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getMul); 728 case Instruction::UDiv: 729 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getUDiv); 730 case Instruction::SDiv: 731 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSDiv); 732 case Instruction::FDiv: 733 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFDiv); 734 case Instruction::URem: 735 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getURem); 736 case Instruction::SRem: 737 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSRem); 738 case Instruction::FRem: 739 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFRem); 740 case Instruction::And: 741 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAnd); 742 case Instruction::Or: 743 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getOr); 744 case Instruction::Xor: 745 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getXor); 746 } 747 } 748 } 749 750 // We don't know how to fold this 751 return 0; 752} 753 754/// isZeroSizedType - This type is zero sized if its an array or structure of 755/// zero sized types. The only leaf zero sized type is an empty structure. 756static bool isMaybeZeroSizedType(const Type *Ty) { 757 if (isa<OpaqueType>(Ty)) return true; // Can't say. 758 if (const StructType *STy = dyn_cast<StructType>(Ty)) { 759 760 // If all of elements have zero size, this does too. 761 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) 762 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; 763 return true; 764 765 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 766 return isMaybeZeroSizedType(ATy->getElementType()); 767 } 768 return false; 769} 770 771/// IdxCompare - Compare the two constants as though they were getelementptr 772/// indices. This allows coersion of the types to be the same thing. 773/// 774/// If the two constants are the "same" (after coersion), return 0. If the 775/// first is less than the second, return -1, if the second is less than the 776/// first, return 1. If the constants are not integral, return -2. 777/// 778static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) { 779 if (C1 == C2) return 0; 780 781 // Ok, we found a different index. If they are not ConstantInt, we can't do 782 // anything with them. 783 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) 784 return -2; // don't know! 785 786 // Ok, we have two differing integer indices. Sign extend them to be the same 787 // type. Long is always big enough, so we use it. 788 if (C1->getType() != Type::Int64Ty) 789 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty); 790 791 if (C2->getType() != Type::Int64Ty) 792 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty); 793 794 if (C1 == C2) return 0; // They are equal 795 796 // If the type being indexed over is really just a zero sized type, there is 797 // no pointer difference being made here. 798 if (isMaybeZeroSizedType(ElTy)) 799 return -2; // dunno. 800 801 // If they are really different, now that they are the same type, then we 802 // found a difference! 803 if (cast<ConstantInt>(C1)->getSExtValue() < 804 cast<ConstantInt>(C2)->getSExtValue()) 805 return -1; 806 else 807 return 1; 808} 809 810/// evaluateFCmpRelation - This function determines if there is anything we can 811/// decide about the two constants provided. This doesn't need to handle simple 812/// things like ConstantFP comparisons, but should instead handle ConstantExprs. 813/// If we can determine that the two constants have a particular relation to 814/// each other, we should return the corresponding FCmpInst predicate, 815/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in 816/// ConstantFoldCompareInstruction. 817/// 818/// To simplify this code we canonicalize the relation so that the first 819/// operand is always the most "complex" of the two. We consider ConstantFP 820/// to be the simplest, and ConstantExprs to be the most complex. 821static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1, 822 const Constant *V2) { 823 assert(V1->getType() == V2->getType() && 824 "Cannot compare values of different types!"); 825 826 // No compile-time operations on this type yet. 827 if (V1->getType() == Type::PPC_FP128Ty) 828 return FCmpInst::BAD_FCMP_PREDICATE; 829 830 // Handle degenerate case quickly 831 if (V1 == V2) return FCmpInst::FCMP_OEQ; 832 833 if (!isa<ConstantExpr>(V1)) { 834 if (!isa<ConstantExpr>(V2)) { 835 // We distilled thisUse the standard constant folder for a few cases 836 ConstantInt *R = 0; 837 Constant *C1 = const_cast<Constant*>(V1); 838 Constant *C2 = const_cast<Constant*>(V2); 839 R = dyn_cast<ConstantInt>( 840 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2)); 841 if (R && !R->isZero()) 842 return FCmpInst::FCMP_OEQ; 843 R = dyn_cast<ConstantInt>( 844 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2)); 845 if (R && !R->isZero()) 846 return FCmpInst::FCMP_OLT; 847 R = dyn_cast<ConstantInt>( 848 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2)); 849 if (R && !R->isZero()) 850 return FCmpInst::FCMP_OGT; 851 852 // Nothing more we can do 853 return FCmpInst::BAD_FCMP_PREDICATE; 854 } 855 856 // If the first operand is simple and second is ConstantExpr, swap operands. 857 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); 858 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) 859 return FCmpInst::getSwappedPredicate(SwappedRelation); 860 } else { 861 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 862 // constantexpr or a simple constant. 863 const ConstantExpr *CE1 = cast<ConstantExpr>(V1); 864 switch (CE1->getOpcode()) { 865 case Instruction::FPTrunc: 866 case Instruction::FPExt: 867 case Instruction::UIToFP: 868 case Instruction::SIToFP: 869 // We might be able to do something with these but we don't right now. 870 break; 871 default: 872 break; 873 } 874 } 875 // There are MANY other foldings that we could perform here. They will 876 // probably be added on demand, as they seem needed. 877 return FCmpInst::BAD_FCMP_PREDICATE; 878} 879 880/// evaluateICmpRelation - This function determines if there is anything we can 881/// decide about the two constants provided. This doesn't need to handle simple 882/// things like integer comparisons, but should instead handle ConstantExprs 883/// and GlobalValues. If we can determine that the two constants have a 884/// particular relation to each other, we should return the corresponding ICmp 885/// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. 886/// 887/// To simplify this code we canonicalize the relation so that the first 888/// operand is always the most "complex" of the two. We consider simple 889/// constants (like ConstantInt) to be the simplest, followed by 890/// GlobalValues, followed by ConstantExpr's (the most complex). 891/// 892static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1, 893 const Constant *V2, 894 bool isSigned) { 895 assert(V1->getType() == V2->getType() && 896 "Cannot compare different types of values!"); 897 if (V1 == V2) return ICmpInst::ICMP_EQ; 898 899 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) { 900 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) { 901 // We distilled this down to a simple case, use the standard constant 902 // folder. 903 ConstantInt *R = 0; 904 Constant *C1 = const_cast<Constant*>(V1); 905 Constant *C2 = const_cast<Constant*>(V2); 906 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; 907 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2)); 908 if (R && !R->isZero()) 909 return pred; 910 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 911 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2)); 912 if (R && !R->isZero()) 913 return pred; 914 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 915 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2)); 916 if (R && !R->isZero()) 917 return pred; 918 919 // If we couldn't figure it out, bail. 920 return ICmpInst::BAD_ICMP_PREDICATE; 921 } 922 923 // If the first operand is simple, swap operands. 924 ICmpInst::Predicate SwappedRelation = 925 evaluateICmpRelation(V2, V1, isSigned); 926 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 927 return ICmpInst::getSwappedPredicate(SwappedRelation); 928 929 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) { 930 if (isa<ConstantExpr>(V2)) { // Swap as necessary. 931 ICmpInst::Predicate SwappedRelation = 932 evaluateICmpRelation(V2, V1, isSigned); 933 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 934 return ICmpInst::getSwappedPredicate(SwappedRelation); 935 else 936 return ICmpInst::BAD_ICMP_PREDICATE; 937 } 938 939 // Now we know that the RHS is a GlobalValue or simple constant, 940 // which (since the types must match) means that it's a ConstantPointerNull. 941 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) { 942 // Don't try to decide equality of aliases. 943 if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2)) 944 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage()) 945 return ICmpInst::ICMP_NE; 946 } else { 947 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); 948 // GlobalVals can never be null. Don't try to evaluate aliases. 949 if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1)) 950 return ICmpInst::ICMP_NE; 951 } 952 } else { 953 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 954 // constantexpr, a CPR, or a simple constant. 955 const ConstantExpr *CE1 = cast<ConstantExpr>(V1); 956 const Constant *CE1Op0 = CE1->getOperand(0); 957 958 switch (CE1->getOpcode()) { 959 case Instruction::Trunc: 960 case Instruction::FPTrunc: 961 case Instruction::FPExt: 962 case Instruction::FPToUI: 963 case Instruction::FPToSI: 964 break; // We can't evaluate floating point casts or truncations. 965 966 case Instruction::UIToFP: 967 case Instruction::SIToFP: 968 case Instruction::BitCast: 969 case Instruction::ZExt: 970 case Instruction::SExt: 971 // If the cast is not actually changing bits, and the second operand is a 972 // null pointer, do the comparison with the pre-casted value. 973 if (V2->isNullValue() && 974 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) { 975 bool sgnd = isSigned; 976 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 977 if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 978 return evaluateICmpRelation(CE1Op0, 979 Constant::getNullValue(CE1Op0->getType()), 980 sgnd); 981 } 982 983 // If the dest type is a pointer type, and the RHS is a constantexpr cast 984 // from the same type as the src of the LHS, evaluate the inputs. This is 985 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)", 986 // which happens a lot in compilers with tagged integers. 987 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) 988 if (CE2->isCast() && isa<PointerType>(CE1->getType()) && 989 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() && 990 CE1->getOperand(0)->getType()->isInteger()) { 991 bool sgnd = isSigned; 992 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 993 if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 994 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0), 995 sgnd); 996 } 997 break; 998 999 case Instruction::GetElementPtr: 1000 // Ok, since this is a getelementptr, we know that the constant has a 1001 // pointer type. Check the various cases. 1002 if (isa<ConstantPointerNull>(V2)) { 1003 // If we are comparing a GEP to a null pointer, check to see if the base 1004 // of the GEP equals the null pointer. 1005 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1006 if (GV->hasExternalWeakLinkage()) 1007 // Weak linkage GVals could be zero or not. We're comparing that 1008 // to null pointer so its greater-or-equal 1009 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; 1010 else 1011 // If its not weak linkage, the GVal must have a non-zero address 1012 // so the result is greater-than 1013 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1014 } else if (isa<ConstantPointerNull>(CE1Op0)) { 1015 // If we are indexing from a null pointer, check to see if we have any 1016 // non-zero indices. 1017 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) 1018 if (!CE1->getOperand(i)->isNullValue()) 1019 // Offsetting from null, must not be equal. 1020 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1021 // Only zero indexes from null, must still be zero. 1022 return ICmpInst::ICMP_EQ; 1023 } 1024 // Otherwise, we can't really say if the first operand is null or not. 1025 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) { 1026 if (isa<ConstantPointerNull>(CE1Op0)) { 1027 if (CPR2->hasExternalWeakLinkage()) 1028 // Weak linkage GVals could be zero or not. We're comparing it to 1029 // a null pointer, so its less-or-equal 1030 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; 1031 else 1032 // If its not weak linkage, the GVal must have a non-zero address 1033 // so the result is less-than 1034 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1035 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) { 1036 if (CPR1 == CPR2) { 1037 // If this is a getelementptr of the same global, then it must be 1038 // different. Because the types must match, the getelementptr could 1039 // only have at most one index, and because we fold getelementptr's 1040 // with a single zero index, it must be nonzero. 1041 assert(CE1->getNumOperands() == 2 && 1042 !CE1->getOperand(1)->isNullValue() && 1043 "Suprising getelementptr!"); 1044 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1045 } else { 1046 // If they are different globals, we don't know what the value is, 1047 // but they can't be equal. 1048 return ICmpInst::ICMP_NE; 1049 } 1050 } 1051 } else { 1052 const ConstantExpr *CE2 = cast<ConstantExpr>(V2); 1053 const Constant *CE2Op0 = CE2->getOperand(0); 1054 1055 // There are MANY other foldings that we could perform here. They will 1056 // probably be added on demand, as they seem needed. 1057 switch (CE2->getOpcode()) { 1058 default: break; 1059 case Instruction::GetElementPtr: 1060 // By far the most common case to handle is when the base pointers are 1061 // obviously to the same or different globals. 1062 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { 1063 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal 1064 return ICmpInst::ICMP_NE; 1065 // Ok, we know that both getelementptr instructions are based on the 1066 // same global. From this, we can precisely determine the relative 1067 // ordering of the resultant pointers. 1068 unsigned i = 1; 1069 1070 // Compare all of the operands the GEP's have in common. 1071 gep_type_iterator GTI = gep_type_begin(CE1); 1072 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); 1073 ++i, ++GTI) 1074 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i), 1075 GTI.getIndexedType())) { 1076 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; 1077 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; 1078 case -2: return ICmpInst::BAD_ICMP_PREDICATE; 1079 } 1080 1081 // Ok, we ran out of things they have in common. If any leftovers 1082 // are non-zero then we have a difference, otherwise we are equal. 1083 for (; i < CE1->getNumOperands(); ++i) 1084 if (!CE1->getOperand(i)->isNullValue()) 1085 if (isa<ConstantInt>(CE1->getOperand(i))) 1086 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1087 else 1088 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1089 1090 for (; i < CE2->getNumOperands(); ++i) 1091 if (!CE2->getOperand(i)->isNullValue()) 1092 if (isa<ConstantInt>(CE2->getOperand(i))) 1093 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1094 else 1095 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1096 return ICmpInst::ICMP_EQ; 1097 } 1098 } 1099 } 1100 default: 1101 break; 1102 } 1103 } 1104 1105 return ICmpInst::BAD_ICMP_PREDICATE; 1106} 1107 1108Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred, 1109 const Constant *C1, 1110 const Constant *C2) { 1111 1112 // Handle some degenerate cases first 1113 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) 1114 return UndefValue::get(Type::Int1Ty); 1115 1116 // No compile-time operations on this type yet. 1117 if (C1->getType() == Type::PPC_FP128Ty) 1118 return 0; 1119 1120 // icmp eq/ne(null,GV) -> false/true 1121 if (C1->isNullValue()) { 1122 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) 1123 // Don't try to evaluate aliases. External weak GV can be null. 1124 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) 1125 if (pred == ICmpInst::ICMP_EQ) 1126 return ConstantInt::getFalse(); 1127 else if (pred == ICmpInst::ICMP_NE) 1128 return ConstantInt::getTrue(); 1129 // icmp eq/ne(GV,null) -> false/true 1130 } else if (C2->isNullValue()) { 1131 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) 1132 // Don't try to evaluate aliases. External weak GV can be null. 1133 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) 1134 if (pred == ICmpInst::ICMP_EQ) 1135 return ConstantInt::getFalse(); 1136 else if (pred == ICmpInst::ICMP_NE) 1137 return ConstantInt::getTrue(); 1138 } 1139 1140 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { 1141 APInt V1 = cast<ConstantInt>(C1)->getValue(); 1142 APInt V2 = cast<ConstantInt>(C2)->getValue(); 1143 switch (pred) { 1144 default: assert(0 && "Invalid ICmp Predicate"); return 0; 1145 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2); 1146 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2); 1147 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2)); 1148 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2)); 1149 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2)); 1150 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2)); 1151 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2)); 1152 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2)); 1153 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2)); 1154 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2)); 1155 } 1156 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { 1157 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); 1158 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); 1159 APFloat::cmpResult R = C1V.compare(C2V); 1160 switch (pred) { 1161 default: assert(0 && "Invalid FCmp Predicate"); return 0; 1162 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse(); 1163 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue(); 1164 case FCmpInst::FCMP_UNO: 1165 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered); 1166 case FCmpInst::FCMP_ORD: 1167 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpUnordered); 1168 case FCmpInst::FCMP_UEQ: 1169 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered || 1170 R==APFloat::cmpEqual); 1171 case FCmpInst::FCMP_OEQ: 1172 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpEqual); 1173 case FCmpInst::FCMP_UNE: 1174 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpEqual); 1175 case FCmpInst::FCMP_ONE: 1176 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan || 1177 R==APFloat::cmpGreaterThan); 1178 case FCmpInst::FCMP_ULT: 1179 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered || 1180 R==APFloat::cmpLessThan); 1181 case FCmpInst::FCMP_OLT: 1182 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan); 1183 case FCmpInst::FCMP_UGT: 1184 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered || 1185 R==APFloat::cmpGreaterThan); 1186 case FCmpInst::FCMP_OGT: 1187 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan); 1188 case FCmpInst::FCMP_ULE: 1189 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpGreaterThan); 1190 case FCmpInst::FCMP_OLE: 1191 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan || 1192 R==APFloat::cmpEqual); 1193 case FCmpInst::FCMP_UGE: 1194 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpLessThan); 1195 case FCmpInst::FCMP_OGE: 1196 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan || 1197 R==APFloat::cmpEqual); 1198 } 1199 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) { 1200 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) { 1201 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) { 1202 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) { 1203 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, 1204 const_cast<Constant*>(CP1->getOperand(i)), 1205 const_cast<Constant*>(CP2->getOperand(i))); 1206 if (ConstantInt *CB = dyn_cast<ConstantInt>(C)) 1207 return CB; 1208 } 1209 // Otherwise, could not decide from any element pairs. 1210 return 0; 1211 } else if (pred == ICmpInst::ICMP_EQ) { 1212 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) { 1213 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ, 1214 const_cast<Constant*>(CP1->getOperand(i)), 1215 const_cast<Constant*>(CP2->getOperand(i))); 1216 if (ConstantInt *CB = dyn_cast<ConstantInt>(C)) 1217 return CB; 1218 } 1219 // Otherwise, could not decide from any element pairs. 1220 return 0; 1221 } 1222 } 1223 } 1224 1225 if (C1->getType()->isFloatingPoint()) { 1226 switch (evaluateFCmpRelation(C1, C2)) { 1227 default: assert(0 && "Unknown relation!"); 1228 case FCmpInst::FCMP_UNO: 1229 case FCmpInst::FCMP_ORD: 1230 case FCmpInst::FCMP_UEQ: 1231 case FCmpInst::FCMP_UNE: 1232 case FCmpInst::FCMP_ULT: 1233 case FCmpInst::FCMP_UGT: 1234 case FCmpInst::FCMP_ULE: 1235 case FCmpInst::FCMP_UGE: 1236 case FCmpInst::FCMP_TRUE: 1237 case FCmpInst::FCMP_FALSE: 1238 case FCmpInst::BAD_FCMP_PREDICATE: 1239 break; // Couldn't determine anything about these constants. 1240 case FCmpInst::FCMP_OEQ: // We know that C1 == C2 1241 return ConstantInt::get(Type::Int1Ty, 1242 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || 1243 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || 1244 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1245 case FCmpInst::FCMP_OLT: // We know that C1 < C2 1246 return ConstantInt::get(Type::Int1Ty, 1247 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1248 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || 1249 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); 1250 case FCmpInst::FCMP_OGT: // We know that C1 > C2 1251 return ConstantInt::get(Type::Int1Ty, 1252 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1253 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || 1254 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1255 case FCmpInst::FCMP_OLE: // We know that C1 <= C2 1256 // We can only partially decide this relation. 1257 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1258 return ConstantInt::getFalse(); 1259 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1260 return ConstantInt::getTrue(); 1261 break; 1262 case FCmpInst::FCMP_OGE: // We known that C1 >= C2 1263 // We can only partially decide this relation. 1264 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1265 return ConstantInt::getFalse(); 1266 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1267 return ConstantInt::getTrue(); 1268 break; 1269 case ICmpInst::ICMP_NE: // We know that C1 != C2 1270 // We can only partially decide this relation. 1271 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) 1272 return ConstantInt::getFalse(); 1273 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) 1274 return ConstantInt::getTrue(); 1275 break; 1276 } 1277 } else { 1278 // Evaluate the relation between the two constants, per the predicate. 1279 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) { 1280 default: assert(0 && "Unknown relational!"); 1281 case ICmpInst::BAD_ICMP_PREDICATE: 1282 break; // Couldn't determine anything about these constants. 1283 case ICmpInst::ICMP_EQ: // We know the constants are equal! 1284 // If we know the constants are equal, we can decide the result of this 1285 // computation precisely. 1286 return ConstantInt::get(Type::Int1Ty, 1287 pred == ICmpInst::ICMP_EQ || 1288 pred == ICmpInst::ICMP_ULE || 1289 pred == ICmpInst::ICMP_SLE || 1290 pred == ICmpInst::ICMP_UGE || 1291 pred == ICmpInst::ICMP_SGE); 1292 case ICmpInst::ICMP_ULT: 1293 // If we know that C1 < C2, we can decide the result of this computation 1294 // precisely. 1295 return ConstantInt::get(Type::Int1Ty, 1296 pred == ICmpInst::ICMP_ULT || 1297 pred == ICmpInst::ICMP_NE || 1298 pred == ICmpInst::ICMP_ULE); 1299 case ICmpInst::ICMP_SLT: 1300 // If we know that C1 < C2, we can decide the result of this computation 1301 // precisely. 1302 return ConstantInt::get(Type::Int1Ty, 1303 pred == ICmpInst::ICMP_SLT || 1304 pred == ICmpInst::ICMP_NE || 1305 pred == ICmpInst::ICMP_SLE); 1306 case ICmpInst::ICMP_UGT: 1307 // If we know that C1 > C2, we can decide the result of this computation 1308 // precisely. 1309 return ConstantInt::get(Type::Int1Ty, 1310 pred == ICmpInst::ICMP_UGT || 1311 pred == ICmpInst::ICMP_NE || 1312 pred == ICmpInst::ICMP_UGE); 1313 case ICmpInst::ICMP_SGT: 1314 // If we know that C1 > C2, we can decide the result of this computation 1315 // precisely. 1316 return ConstantInt::get(Type::Int1Ty, 1317 pred == ICmpInst::ICMP_SGT || 1318 pred == ICmpInst::ICMP_NE || 1319 pred == ICmpInst::ICMP_SGE); 1320 case ICmpInst::ICMP_ULE: 1321 // If we know that C1 <= C2, we can only partially decide this relation. 1322 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse(); 1323 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue(); 1324 break; 1325 case ICmpInst::ICMP_SLE: 1326 // If we know that C1 <= C2, we can only partially decide this relation. 1327 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse(); 1328 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue(); 1329 break; 1330 1331 case ICmpInst::ICMP_UGE: 1332 // If we know that C1 >= C2, we can only partially decide this relation. 1333 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse(); 1334 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue(); 1335 break; 1336 case ICmpInst::ICMP_SGE: 1337 // If we know that C1 >= C2, we can only partially decide this relation. 1338 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse(); 1339 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue(); 1340 break; 1341 1342 case ICmpInst::ICMP_NE: 1343 // If we know that C1 != C2, we can only partially decide this relation. 1344 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse(); 1345 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue(); 1346 break; 1347 } 1348 1349 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) { 1350 // If C2 is a constant expr and C1 isn't, flop them around and fold the 1351 // other way if possible. 1352 switch (pred) { 1353 case ICmpInst::ICMP_EQ: 1354 case ICmpInst::ICMP_NE: 1355 // No change of predicate required. 1356 return ConstantFoldCompareInstruction(pred, C2, C1); 1357 1358 case ICmpInst::ICMP_ULT: 1359 case ICmpInst::ICMP_SLT: 1360 case ICmpInst::ICMP_UGT: 1361 case ICmpInst::ICMP_SGT: 1362 case ICmpInst::ICMP_ULE: 1363 case ICmpInst::ICMP_SLE: 1364 case ICmpInst::ICMP_UGE: 1365 case ICmpInst::ICMP_SGE: 1366 // Change the predicate as necessary to swap the operands. 1367 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); 1368 return ConstantFoldCompareInstruction(pred, C2, C1); 1369 1370 default: // These predicates cannot be flopped around. 1371 break; 1372 } 1373 } 1374 } 1375 return 0; 1376} 1377 1378Constant *llvm::ConstantFoldGetElementPtr(const Constant *C, 1379 Constant* const *Idxs, 1380 unsigned NumIdx) { 1381 if (NumIdx == 0 || 1382 (NumIdx == 1 && Idxs[0]->isNullValue())) 1383 return const_cast<Constant*>(C); 1384 1385 if (isa<UndefValue>(C)) { 1386 const PointerType *Ptr = cast<PointerType>(C->getType()); 1387 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr, 1388 (Value **)Idxs, 1389 (Value **)Idxs+NumIdx, 1390 true); 1391 assert(Ty != 0 && "Invalid indices for GEP!"); 1392 return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); 1393 } 1394 1395 Constant *Idx0 = Idxs[0]; 1396 if (C->isNullValue()) { 1397 bool isNull = true; 1398 for (unsigned i = 0, e = NumIdx; i != e; ++i) 1399 if (!Idxs[i]->isNullValue()) { 1400 isNull = false; 1401 break; 1402 } 1403 if (isNull) { 1404 const PointerType *Ptr = cast<PointerType>(C->getType()); 1405 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr, 1406 (Value**)Idxs, 1407 (Value**)Idxs+NumIdx, 1408 true); 1409 assert(Ty != 0 && "Invalid indices for GEP!"); 1410 return 1411 ConstantPointerNull::get(PointerType::get(Ty,Ptr->getAddressSpace())); 1412 } 1413 } 1414 1415 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) { 1416 // Combine Indices - If the source pointer to this getelementptr instruction 1417 // is a getelementptr instruction, combine the indices of the two 1418 // getelementptr instructions into a single instruction. 1419 // 1420 if (CE->getOpcode() == Instruction::GetElementPtr) { 1421 const Type *LastTy = 0; 1422 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); 1423 I != E; ++I) 1424 LastTy = *I; 1425 1426 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) { 1427 SmallVector<Value*, 16> NewIndices; 1428 NewIndices.reserve(NumIdx + CE->getNumOperands()); 1429 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) 1430 NewIndices.push_back(CE->getOperand(i)); 1431 1432 // Add the last index of the source with the first index of the new GEP. 1433 // Make sure to handle the case when they are actually different types. 1434 Constant *Combined = CE->getOperand(CE->getNumOperands()-1); 1435 // Otherwise it must be an array. 1436 if (!Idx0->isNullValue()) { 1437 const Type *IdxTy = Combined->getType(); 1438 if (IdxTy != Idx0->getType()) { 1439 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty); 1440 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, 1441 Type::Int64Ty); 1442 Combined = ConstantExpr::get(Instruction::Add, C1, C2); 1443 } else { 1444 Combined = 1445 ConstantExpr::get(Instruction::Add, Idx0, Combined); 1446 } 1447 } 1448 1449 NewIndices.push_back(Combined); 1450 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx); 1451 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0], 1452 NewIndices.size()); 1453 } 1454 } 1455 1456 // Implement folding of: 1457 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*), 1458 // long 0, long 0) 1459 // To: int* getelementptr ([3 x int]* %X, long 0, long 0) 1460 // 1461 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) { 1462 if (const PointerType *SPT = 1463 dyn_cast<PointerType>(CE->getOperand(0)->getType())) 1464 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType())) 1465 if (const ArrayType *CAT = 1466 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType())) 1467 if (CAT->getElementType() == SAT->getElementType()) 1468 return ConstantExpr::getGetElementPtr( 1469 (Constant*)CE->getOperand(0), Idxs, NumIdx); 1470 } 1471 1472 // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1) 1473 // Into: inttoptr (i64 0 to i8*) 1474 // This happens with pointers to member functions in C++. 1475 if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 && 1476 isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) && 1477 cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) { 1478 Constant *Base = CE->getOperand(0); 1479 Constant *Offset = Idxs[0]; 1480 1481 // Convert the smaller integer to the larger type. 1482 if (Offset->getType()->getPrimitiveSizeInBits() < 1483 Base->getType()->getPrimitiveSizeInBits()) 1484 Offset = ConstantExpr::getSExt(Offset, Base->getType()); 1485 else if (Base->getType()->getPrimitiveSizeInBits() < 1486 Offset->getType()->getPrimitiveSizeInBits()) 1487 Base = ConstantExpr::getZExt(Base, Base->getType()); 1488 1489 Base = ConstantExpr::getAdd(Base, Offset); 1490 return ConstantExpr::getIntToPtr(Base, CE->getType()); 1491 } 1492 } 1493 return 0; 1494} 1495 1496