ConstantFold.cpp revision 3e5d1d8d0839e98ee203aa3e3c4fe84ef71eba2c
1//===- ConstantFold.cpp - LLVM constant folder ----------------------------===// 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 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 if (PTy->getAddressSpace() == DPTy->getAddressSpace()) { 101 SmallVector<Value*, 8> IdxList; 102 IdxList.push_back(Constant::getNullValue(Type::Int32Ty)); 103 const Type *ElTy = PTy->getElementType(); 104 while (ElTy != DPTy->getElementType()) { 105 if (const StructType *STy = dyn_cast<StructType>(ElTy)) { 106 if (STy->getNumElements() == 0) break; 107 ElTy = STy->getElementType(0); 108 IdxList.push_back(Constant::getNullValue(Type::Int32Ty)); 109 } else if (const SequentialType *STy = 110 dyn_cast<SequentialType>(ElTy)) { 111 if (isa<PointerType>(ElTy)) break; // Can't index into pointers! 112 ElTy = STy->getElementType(); 113 IdxList.push_back(IdxList[0]); 114 } else { 115 break; 116 } 117 } 118 119 if (ElTy == DPTy->getElementType()) 120 return ConstantExpr::getGetElementPtr(V, &IdxList[0], IdxList.size()); 121 } 122 123 // Handle casts from one vector constant to another. We know that the src 124 // and dest type have the same size (otherwise its an illegal cast). 125 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { 126 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { 127 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && 128 "Not cast between same sized vectors!"); 129 // First, check for null. Undef is already handled. 130 if (isa<ConstantAggregateZero>(V)) 131 return Constant::getNullValue(DestTy); 132 133 if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) 134 return BitCastConstantVector(CV, DestPTy); 135 } 136 } 137 138 // Finally, implement bitcast folding now. The code below doesn't handle 139 // bitcast right. 140 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. 141 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 142 143 // Handle integral constant input. 144 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 145 if (DestTy->isInteger()) 146 // Integral -> Integral. This is a no-op because the bit widths must 147 // be the same. Consequently, we just fold to V. 148 return V; 149 150 if (DestTy->isFloatingPoint()) { 151 assert((DestTy == Type::DoubleTy || DestTy == Type::FloatTy) && 152 "Unknown FP type!"); 153 return ConstantFP::get(APFloat(CI->getValue())); 154 } 155 // Otherwise, can't fold this (vector?) 156 return 0; 157 } 158 159 // Handle ConstantFP input. 160 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) { 161 // FP -> Integral. 162 if (DestTy == Type::Int32Ty) { 163 return ConstantInt::get(FP->getValueAPF().convertToAPInt()); 164 } else { 165 assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!"); 166 return ConstantInt::get(FP->getValueAPF().convertToAPInt()); 167 } 168 } 169 return 0; 170} 171 172 173Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V, 174 const Type *DestTy) { 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 // [us]itofp(undef) = 0, because the result value is bounded. 179 if (opc == Instruction::ZExt || opc == Instruction::SExt || 180 opc == Instruction::UIToFP || opc == Instruction::SIToFP) 181 return Constant::getNullValue(DestTy); 182 return UndefValue::get(DestTy); 183 } 184 // No compile-time operations on this type yet. 185 if (V->getType() == Type::PPC_FP128Ty || DestTy == Type::PPC_FP128Ty) 186 return 0; 187 188 // If the cast operand is a constant expression, there's a few things we can 189 // do to try to simplify it. 190 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 191 if (CE->isCast()) { 192 // Try hard to fold cast of cast because they are often eliminable. 193 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) 194 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); 195 } else if (CE->getOpcode() == Instruction::GetElementPtr) { 196 // If all of the indexes in the GEP are null values, there is no pointer 197 // adjustment going on. We might as well cast the source pointer. 198 bool isAllNull = true; 199 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) 200 if (!CE->getOperand(i)->isNullValue()) { 201 isAllNull = false; 202 break; 203 } 204 if (isAllNull) 205 // This is casting one pointer type to another, always BitCast 206 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); 207 } 208 } 209 210 // We actually have to do a cast now. Perform the cast according to the 211 // opcode specified. 212 switch (opc) { 213 case Instruction::FPTrunc: 214 case Instruction::FPExt: 215 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 216 APFloat Val = FPC->getValueAPF(); 217 Val.convert(DestTy == Type::FloatTy ? APFloat::IEEEsingle : 218 DestTy == Type::DoubleTy ? APFloat::IEEEdouble : 219 DestTy == Type::X86_FP80Ty ? APFloat::x87DoubleExtended : 220 DestTy == Type::FP128Ty ? APFloat::IEEEquad : 221 APFloat::Bogus, 222 APFloat::rmNearestTiesToEven); 223 return ConstantFP::get(Val); 224 } 225 return 0; // Can't fold. 226 case Instruction::FPToUI: 227 case Instruction::FPToSI: 228 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 229 const APFloat &V = FPC->getValueAPF(); 230 uint64_t x[2]; 231 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 232 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, 233 APFloat::rmTowardZero); 234 APInt Val(DestBitWidth, 2, x); 235 return ConstantInt::get(Val); 236 } 237 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) { 238 std::vector<Constant*> res; 239 const VectorType *DestVecTy = cast<VectorType>(DestTy); 240 const Type *DstEltTy = DestVecTy->getElementType(); 241 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) 242 res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i), 243 DstEltTy)); 244 return ConstantVector::get(DestVecTy, res); 245 } 246 return 0; // Can't fold. 247 case Instruction::IntToPtr: //always treated as unsigned 248 if (V->isNullValue()) // Is it an integral null value? 249 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 250 return 0; // Other pointer types cannot be casted 251 case Instruction::PtrToInt: // always treated as unsigned 252 if (V->isNullValue()) // is it a null pointer value? 253 return ConstantInt::get(DestTy, 0); 254 return 0; // Other pointer types cannot be casted 255 case Instruction::UIToFP: 256 case Instruction::SIToFP: 257 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 258 APInt api = CI->getValue(); 259 const uint64_t zero[] = {0, 0}; 260 APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(), 261 2, zero)); 262 (void)apf.convertFromAPInt(api, 263 opc==Instruction::SIToFP, 264 APFloat::rmNearestTiesToEven); 265 return ConstantFP::get(apf); 266 } 267 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) { 268 std::vector<Constant*> res; 269 const VectorType *DestVecTy = cast<VectorType>(DestTy); 270 const Type *DstEltTy = DestVecTy->getElementType(); 271 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) 272 res.push_back(ConstantFoldCastInstruction(opc, V->getOperand(i), 273 DstEltTy)); 274 return ConstantVector::get(DestVecTy, res); 275 } 276 return 0; 277 case Instruction::ZExt: 278 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 279 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 280 APInt Result(CI->getValue()); 281 Result.zext(BitWidth); 282 return ConstantInt::get(Result); 283 } 284 return 0; 285 case Instruction::SExt: 286 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 287 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 288 APInt Result(CI->getValue()); 289 Result.sext(BitWidth); 290 return ConstantInt::get(Result); 291 } 292 return 0; 293 case Instruction::Trunc: 294 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 295 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 296 APInt Result(CI->getValue()); 297 Result.trunc(BitWidth); 298 return ConstantInt::get(Result); 299 } 300 return 0; 301 case Instruction::BitCast: 302 return FoldBitCast(const_cast<Constant*>(V), DestTy); 303 default: 304 assert(!"Invalid CE CastInst opcode"); 305 break; 306 } 307 308 assert(0 && "Failed to cast constant expression"); 309 return 0; 310} 311 312Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond, 313 const Constant *V1, 314 const Constant *V2) { 315 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond)) 316 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2); 317 318 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2); 319 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1); 320 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1); 321 if (V1 == V2) return const_cast<Constant*>(V1); 322 return 0; 323} 324 325Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val, 326 const Constant *Idx) { 327 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef 328 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType()); 329 if (Val->isNullValue()) // ee(zero, x) -> zero 330 return Constant::getNullValue( 331 cast<VectorType>(Val->getType())->getElementType()); 332 333 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { 334 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { 335 return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue())); 336 } else if (isa<UndefValue>(Idx)) { 337 // ee({w,x,y,z}, undef) -> w (an arbitrary value). 338 return const_cast<Constant*>(CVal->getOperand(0)); 339 } 340 } 341 return 0; 342} 343 344Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val, 345 const Constant *Elt, 346 const Constant *Idx) { 347 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); 348 if (!CIdx) return 0; 349 APInt idxVal = CIdx->getValue(); 350 if (isa<UndefValue>(Val)) { 351 // Insertion of scalar constant into vector undef 352 // Optimize away insertion of undef 353 if (isa<UndefValue>(Elt)) 354 return const_cast<Constant*>(Val); 355 // Otherwise break the aggregate undef into multiple undefs and do 356 // the insertion 357 unsigned numOps = 358 cast<VectorType>(Val->getType())->getNumElements(); 359 std::vector<Constant*> Ops; 360 Ops.reserve(numOps); 361 for (unsigned i = 0; i < numOps; ++i) { 362 const Constant *Op = 363 (idxVal == i) ? Elt : UndefValue::get(Elt->getType()); 364 Ops.push_back(const_cast<Constant*>(Op)); 365 } 366 return ConstantVector::get(Ops); 367 } 368 if (isa<ConstantAggregateZero>(Val)) { 369 // Insertion of scalar constant into vector aggregate zero 370 // Optimize away insertion of zero 371 if (Elt->isNullValue()) 372 return const_cast<Constant*>(Val); 373 // Otherwise break the aggregate zero into multiple zeros and do 374 // the insertion 375 unsigned numOps = 376 cast<VectorType>(Val->getType())->getNumElements(); 377 std::vector<Constant*> Ops; 378 Ops.reserve(numOps); 379 for (unsigned i = 0; i < numOps; ++i) { 380 const Constant *Op = 381 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType()); 382 Ops.push_back(const_cast<Constant*>(Op)); 383 } 384 return ConstantVector::get(Ops); 385 } 386 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { 387 // Insertion of scalar constant into vector constant 388 std::vector<Constant*> Ops; 389 Ops.reserve(CVal->getNumOperands()); 390 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) { 391 const Constant *Op = 392 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i)); 393 Ops.push_back(const_cast<Constant*>(Op)); 394 } 395 return ConstantVector::get(Ops); 396 } 397 return 0; 398} 399 400/// GetVectorElement - If C is a ConstantVector, ConstantAggregateZero or Undef 401/// return the specified element value. Otherwise return null. 402static Constant *GetVectorElement(const Constant *C, unsigned EltNo) { 403 if (const ConstantVector *CV = dyn_cast<ConstantVector>(C)) 404 return const_cast<Constant*>(CV->getOperand(EltNo)); 405 406 const Type *EltTy = cast<VectorType>(C->getType())->getElementType(); 407 if (isa<ConstantAggregateZero>(C)) 408 return Constant::getNullValue(EltTy); 409 if (isa<UndefValue>(C)) 410 return UndefValue::get(EltTy); 411 return 0; 412} 413 414Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1, 415 const Constant *V2, 416 const Constant *Mask) { 417 // Undefined shuffle mask -> undefined value. 418 if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType()); 419 420 unsigned NumElts = cast<VectorType>(V1->getType())->getNumElements(); 421 const Type *EltTy = cast<VectorType>(V1->getType())->getElementType(); 422 423 // Loop over the shuffle mask, evaluating each element. 424 SmallVector<Constant*, 32> Result; 425 for (unsigned i = 0; i != NumElts; ++i) { 426 Constant *InElt = GetVectorElement(Mask, i); 427 if (InElt == 0) return 0; 428 429 if (isa<UndefValue>(InElt)) 430 InElt = UndefValue::get(EltTy); 431 else if (ConstantInt *CI = dyn_cast<ConstantInt>(InElt)) { 432 unsigned Elt = CI->getZExtValue(); 433 if (Elt >= NumElts*2) 434 InElt = UndefValue::get(EltTy); 435 else if (Elt >= NumElts) 436 InElt = GetVectorElement(V2, Elt-NumElts); 437 else 438 InElt = GetVectorElement(V1, Elt); 439 if (InElt == 0) return 0; 440 } else { 441 // Unknown value. 442 return 0; 443 } 444 Result.push_back(InElt); 445 } 446 447 return ConstantVector::get(&Result[0], Result.size()); 448} 449 450/// EvalVectorOp - Given two vector constants and a function pointer, apply the 451/// function pointer to each element pair, producing a new ConstantVector 452/// constant. Either or both of V1 and V2 may be NULL, meaning a 453/// ConstantAggregateZero operand. 454static Constant *EvalVectorOp(const ConstantVector *V1, 455 const ConstantVector *V2, 456 const VectorType *VTy, 457 Constant *(*FP)(Constant*, Constant*)) { 458 std::vector<Constant*> Res; 459 const Type *EltTy = VTy->getElementType(); 460 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 461 const Constant *C1 = V1 ? V1->getOperand(i) : Constant::getNullValue(EltTy); 462 const Constant *C2 = V2 ? V2->getOperand(i) : Constant::getNullValue(EltTy); 463 Res.push_back(FP(const_cast<Constant*>(C1), 464 const_cast<Constant*>(C2))); 465 } 466 return ConstantVector::get(Res); 467} 468 469Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, 470 const Constant *C1, 471 const Constant *C2) { 472 // No compile-time operations on this type yet. 473 if (C1->getType() == Type::PPC_FP128Ty) 474 return 0; 475 476 // Handle UndefValue up front 477 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 478 switch (Opcode) { 479 case Instruction::Xor: 480 if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) 481 // Handle undef ^ undef -> 0 special case. This is a common 482 // idiom (misuse). 483 return Constant::getNullValue(C1->getType()); 484 // Fallthrough 485 case Instruction::Add: 486 case Instruction::Sub: 487 return UndefValue::get(C1->getType()); 488 case Instruction::Mul: 489 case Instruction::And: 490 return Constant::getNullValue(C1->getType()); 491 case Instruction::UDiv: 492 case Instruction::SDiv: 493 case Instruction::FDiv: 494 case Instruction::URem: 495 case Instruction::SRem: 496 case Instruction::FRem: 497 if (!isa<UndefValue>(C2)) // undef / X -> 0 498 return Constant::getNullValue(C1->getType()); 499 return const_cast<Constant*>(C2); // X / undef -> undef 500 case Instruction::Or: // X | undef -> -1 501 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType())) 502 return ConstantVector::getAllOnesValue(PTy); 503 return ConstantInt::getAllOnesValue(C1->getType()); 504 case Instruction::LShr: 505 if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) 506 return const_cast<Constant*>(C1); // undef lshr undef -> undef 507 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 508 // undef lshr X -> 0 509 case Instruction::AShr: 510 if (!isa<UndefValue>(C2)) 511 return const_cast<Constant*>(C1); // undef ashr X --> undef 512 else if (isa<UndefValue>(C1)) 513 return const_cast<Constant*>(C1); // undef ashr undef -> undef 514 else 515 return const_cast<Constant*>(C1); // X ashr undef --> X 516 case Instruction::Shl: 517 // undef << X -> 0 or X << undef -> 0 518 return Constant::getNullValue(C1->getType()); 519 } 520 } 521 522 // Handle simplifications of the RHS when a constant int. 523 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 524 switch (Opcode) { 525 case Instruction::Add: 526 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X + 0 == X 527 break; 528 case Instruction::Sub: 529 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X - 0 == X 530 break; 531 case Instruction::Mul: 532 if (CI2->equalsInt(0)) return const_cast<Constant*>(C2); // X * 0 == 0 533 if (CI2->equalsInt(1)) 534 return const_cast<Constant*>(C1); // X * 1 == X 535 break; 536 case Instruction::UDiv: 537 case Instruction::SDiv: 538 if (CI2->equalsInt(1)) 539 return const_cast<Constant*>(C1); // X / 1 == X 540 break; 541 case Instruction::URem: 542 case Instruction::SRem: 543 if (CI2->equalsInt(1)) 544 return Constant::getNullValue(CI2->getType()); // X % 1 == 0 545 break; 546 case Instruction::And: 547 if (CI2->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0 548 if (CI2->isAllOnesValue()) 549 return const_cast<Constant*>(C1); // X & -1 == X 550 551 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 552 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) 553 if (CE1->getOpcode() == Instruction::ZExt) { 554 unsigned DstWidth = CI2->getType()->getBitWidth(); 555 unsigned SrcWidth = 556 CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); 557 APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); 558 if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) 559 return const_cast<Constant*>(C1); 560 } 561 562 // If and'ing the address of a global with a constant, fold it. 563 if (CE1->getOpcode() == Instruction::PtrToInt && 564 isa<GlobalValue>(CE1->getOperand(0))) { 565 GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0)); 566 567 // Functions are at least 4-byte aligned. 568 unsigned GVAlign = GV->getAlignment(); 569 if (isa<Function>(GV)) 570 GVAlign = std::max(GVAlign, 4U); 571 572 if (GVAlign > 1) { 573 unsigned DstWidth = CI2->getType()->getBitWidth(); 574 unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign)); 575 APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth)); 576 577 // If checking bits we know are clear, return zero. 578 if ((CI2->getValue() & BitsNotSet) == CI2->getValue()) 579 return Constant::getNullValue(CI2->getType()); 580 } 581 } 582 } 583 break; 584 case Instruction::Or: 585 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X | 0 == X 586 if (CI2->isAllOnesValue()) 587 return const_cast<Constant*>(C2); // X | -1 == -1 588 break; 589 case Instruction::Xor: 590 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X ^ 0 == X 591 break; 592 case Instruction::AShr: 593 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 594 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) 595 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. 596 return ConstantExpr::getLShr(const_cast<Constant*>(C1), 597 const_cast<Constant*>(C2)); 598 break; 599 } 600 } 601 602 // At this point we know neither constant is an UndefValue. 603 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { 604 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 605 using namespace APIntOps; 606 const APInt &C1V = CI1->getValue(); 607 const APInt &C2V = CI2->getValue(); 608 switch (Opcode) { 609 default: 610 break; 611 case Instruction::Add: 612 return ConstantInt::get(C1V + C2V); 613 case Instruction::Sub: 614 return ConstantInt::get(C1V - C2V); 615 case Instruction::Mul: 616 return ConstantInt::get(C1V * C2V); 617 case Instruction::UDiv: 618 if (CI2->isNullValue()) 619 return 0; // X / 0 -> can't fold 620 return ConstantInt::get(C1V.udiv(C2V)); 621 case Instruction::SDiv: 622 if (CI2->isNullValue()) 623 return 0; // X / 0 -> can't fold 624 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 625 return 0; // MIN_INT / -1 -> overflow 626 return ConstantInt::get(C1V.sdiv(C2V)); 627 case Instruction::URem: 628 if (C2->isNullValue()) 629 return 0; // X / 0 -> can't fold 630 return ConstantInt::get(C1V.urem(C2V)); 631 case Instruction::SRem: 632 if (CI2->isNullValue()) 633 return 0; // X % 0 -> can't fold 634 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 635 return 0; // MIN_INT % -1 -> overflow 636 return ConstantInt::get(C1V.srem(C2V)); 637 case Instruction::And: 638 return ConstantInt::get(C1V & C2V); 639 case Instruction::Or: 640 return ConstantInt::get(C1V | C2V); 641 case Instruction::Xor: 642 return ConstantInt::get(C1V ^ C2V); 643 case Instruction::Shl: { 644 uint32_t shiftAmt = C2V.getZExtValue(); 645 if (shiftAmt < C1V.getBitWidth()) 646 return ConstantInt::get(C1V.shl(shiftAmt)); 647 else 648 return UndefValue::get(C1->getType()); // too big shift is undef 649 } 650 case Instruction::LShr: { 651 uint32_t shiftAmt = C2V.getZExtValue(); 652 if (shiftAmt < C1V.getBitWidth()) 653 return ConstantInt::get(C1V.lshr(shiftAmt)); 654 else 655 return UndefValue::get(C1->getType()); // too big shift is undef 656 } 657 case Instruction::AShr: { 658 uint32_t shiftAmt = C2V.getZExtValue(); 659 if (shiftAmt < C1V.getBitWidth()) 660 return ConstantInt::get(C1V.ashr(shiftAmt)); 661 else 662 return UndefValue::get(C1->getType()); // too big shift is undef 663 } 664 } 665 } 666 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { 667 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { 668 APFloat C1V = CFP1->getValueAPF(); 669 APFloat C2V = CFP2->getValueAPF(); 670 APFloat C3V = C1V; // copy for modification 671 switch (Opcode) { 672 default: 673 break; 674 case Instruction::Add: 675 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); 676 return ConstantFP::get(C3V); 677 case Instruction::Sub: 678 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); 679 return ConstantFP::get(C3V); 680 case Instruction::Mul: 681 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); 682 return ConstantFP::get(C3V); 683 case Instruction::FDiv: 684 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); 685 return ConstantFP::get(C3V); 686 case Instruction::FRem: 687 if (C2V.isZero()) { 688 // IEEE 754, Section 7.1, #5 689 if (CFP1->getType() == Type::DoubleTy) 690 return ConstantFP::get(APFloat(std::numeric_limits<double>:: 691 quiet_NaN())); 692 if (CFP1->getType() == Type::FloatTy) 693 return ConstantFP::get(APFloat(std::numeric_limits<float>:: 694 quiet_NaN())); 695 break; 696 } 697 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven); 698 return ConstantFP::get(C3V); 699 } 700 } 701 } else if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { 702 const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1); 703 const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2); 704 if ((CP1 != NULL || isa<ConstantAggregateZero>(C1)) && 705 (CP2 != NULL || isa<ConstantAggregateZero>(C2))) { 706 switch (Opcode) { 707 default: 708 break; 709 case Instruction::Add: 710 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAdd); 711 case Instruction::Sub: 712 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSub); 713 case Instruction::Mul: 714 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getMul); 715 case Instruction::UDiv: 716 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getUDiv); 717 case Instruction::SDiv: 718 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSDiv); 719 case Instruction::FDiv: 720 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFDiv); 721 case Instruction::URem: 722 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getURem); 723 case Instruction::SRem: 724 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSRem); 725 case Instruction::FRem: 726 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFRem); 727 case Instruction::And: 728 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAnd); 729 case Instruction::Or: 730 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getOr); 731 case Instruction::Xor: 732 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getXor); 733 } 734 } 735 } 736 737 if (isa<ConstantExpr>(C1)) { 738 // There are many possible foldings we could do here. We should probably 739 // at least fold add of a pointer with an integer into the appropriate 740 // getelementptr. This will improve alias analysis a bit. 741 } else if (isa<ConstantExpr>(C2)) { 742 // If C2 is a constant expr and C1 isn't, flop them around and fold the 743 // other way if possible. 744 switch (Opcode) { 745 case Instruction::Add: 746 case Instruction::Mul: 747 case Instruction::And: 748 case Instruction::Or: 749 case Instruction::Xor: 750 // No change of opcode required. 751 return ConstantFoldBinaryInstruction(Opcode, C2, C1); 752 753 case Instruction::Shl: 754 case Instruction::LShr: 755 case Instruction::AShr: 756 case Instruction::Sub: 757 case Instruction::SDiv: 758 case Instruction::UDiv: 759 case Instruction::FDiv: 760 case Instruction::URem: 761 case Instruction::SRem: 762 case Instruction::FRem: 763 default: // These instructions cannot be flopped around. 764 break; 765 } 766 } 767 768 // We don't know how to fold this. 769 return 0; 770} 771 772/// isZeroSizedType - This type is zero sized if its an array or structure of 773/// zero sized types. The only leaf zero sized type is an empty structure. 774static bool isMaybeZeroSizedType(const Type *Ty) { 775 if (isa<OpaqueType>(Ty)) return true; // Can't say. 776 if (const StructType *STy = dyn_cast<StructType>(Ty)) { 777 778 // If all of elements have zero size, this does too. 779 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) 780 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; 781 return true; 782 783 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 784 return isMaybeZeroSizedType(ATy->getElementType()); 785 } 786 return false; 787} 788 789/// IdxCompare - Compare the two constants as though they were getelementptr 790/// indices. This allows coersion of the types to be the same thing. 791/// 792/// If the two constants are the "same" (after coersion), return 0. If the 793/// first is less than the second, return -1, if the second is less than the 794/// first, return 1. If the constants are not integral, return -2. 795/// 796static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) { 797 if (C1 == C2) return 0; 798 799 // Ok, we found a different index. If they are not ConstantInt, we can't do 800 // anything with them. 801 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) 802 return -2; // don't know! 803 804 // Ok, we have two differing integer indices. Sign extend them to be the same 805 // type. Long is always big enough, so we use it. 806 if (C1->getType() != Type::Int64Ty) 807 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty); 808 809 if (C2->getType() != Type::Int64Ty) 810 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty); 811 812 if (C1 == C2) return 0; // They are equal 813 814 // If the type being indexed over is really just a zero sized type, there is 815 // no pointer difference being made here. 816 if (isMaybeZeroSizedType(ElTy)) 817 return -2; // dunno. 818 819 // If they are really different, now that they are the same type, then we 820 // found a difference! 821 if (cast<ConstantInt>(C1)->getSExtValue() < 822 cast<ConstantInt>(C2)->getSExtValue()) 823 return -1; 824 else 825 return 1; 826} 827 828/// evaluateFCmpRelation - This function determines if there is anything we can 829/// decide about the two constants provided. This doesn't need to handle simple 830/// things like ConstantFP comparisons, but should instead handle ConstantExprs. 831/// If we can determine that the two constants have a particular relation to 832/// each other, we should return the corresponding FCmpInst predicate, 833/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in 834/// ConstantFoldCompareInstruction. 835/// 836/// To simplify this code we canonicalize the relation so that the first 837/// operand is always the most "complex" of the two. We consider ConstantFP 838/// to be the simplest, and ConstantExprs to be the most complex. 839static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1, 840 const Constant *V2) { 841 assert(V1->getType() == V2->getType() && 842 "Cannot compare values of different types!"); 843 844 // No compile-time operations on this type yet. 845 if (V1->getType() == Type::PPC_FP128Ty) 846 return FCmpInst::BAD_FCMP_PREDICATE; 847 848 // Handle degenerate case quickly 849 if (V1 == V2) return FCmpInst::FCMP_OEQ; 850 851 if (!isa<ConstantExpr>(V1)) { 852 if (!isa<ConstantExpr>(V2)) { 853 // We distilled thisUse the standard constant folder for a few cases 854 ConstantInt *R = 0; 855 Constant *C1 = const_cast<Constant*>(V1); 856 Constant *C2 = const_cast<Constant*>(V2); 857 R = dyn_cast<ConstantInt>( 858 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2)); 859 if (R && !R->isZero()) 860 return FCmpInst::FCMP_OEQ; 861 R = dyn_cast<ConstantInt>( 862 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2)); 863 if (R && !R->isZero()) 864 return FCmpInst::FCMP_OLT; 865 R = dyn_cast<ConstantInt>( 866 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2)); 867 if (R && !R->isZero()) 868 return FCmpInst::FCMP_OGT; 869 870 // Nothing more we can do 871 return FCmpInst::BAD_FCMP_PREDICATE; 872 } 873 874 // If the first operand is simple and second is ConstantExpr, swap operands. 875 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); 876 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) 877 return FCmpInst::getSwappedPredicate(SwappedRelation); 878 } else { 879 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 880 // constantexpr or a simple constant. 881 const ConstantExpr *CE1 = cast<ConstantExpr>(V1); 882 switch (CE1->getOpcode()) { 883 case Instruction::FPTrunc: 884 case Instruction::FPExt: 885 case Instruction::UIToFP: 886 case Instruction::SIToFP: 887 // We might be able to do something with these but we don't right now. 888 break; 889 default: 890 break; 891 } 892 } 893 // There are MANY other foldings that we could perform here. They will 894 // probably be added on demand, as they seem needed. 895 return FCmpInst::BAD_FCMP_PREDICATE; 896} 897 898/// evaluateICmpRelation - This function determines if there is anything we can 899/// decide about the two constants provided. This doesn't need to handle simple 900/// things like integer comparisons, but should instead handle ConstantExprs 901/// and GlobalValues. If we can determine that the two constants have a 902/// particular relation to each other, we should return the corresponding ICmp 903/// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. 904/// 905/// To simplify this code we canonicalize the relation so that the first 906/// operand is always the most "complex" of the two. We consider simple 907/// constants (like ConstantInt) to be the simplest, followed by 908/// GlobalValues, followed by ConstantExpr's (the most complex). 909/// 910static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1, 911 const Constant *V2, 912 bool isSigned) { 913 assert(V1->getType() == V2->getType() && 914 "Cannot compare different types of values!"); 915 if (V1 == V2) return ICmpInst::ICMP_EQ; 916 917 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) { 918 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) { 919 // We distilled this down to a simple case, use the standard constant 920 // folder. 921 ConstantInt *R = 0; 922 Constant *C1 = const_cast<Constant*>(V1); 923 Constant *C2 = const_cast<Constant*>(V2); 924 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; 925 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2)); 926 if (R && !R->isZero()) 927 return pred; 928 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 929 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2)); 930 if (R && !R->isZero()) 931 return pred; 932 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 933 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2)); 934 if (R && !R->isZero()) 935 return pred; 936 937 // If we couldn't figure it out, bail. 938 return ICmpInst::BAD_ICMP_PREDICATE; 939 } 940 941 // If the first operand is simple, swap operands. 942 ICmpInst::Predicate SwappedRelation = 943 evaluateICmpRelation(V2, V1, isSigned); 944 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 945 return ICmpInst::getSwappedPredicate(SwappedRelation); 946 947 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) { 948 if (isa<ConstantExpr>(V2)) { // Swap as necessary. 949 ICmpInst::Predicate SwappedRelation = 950 evaluateICmpRelation(V2, V1, isSigned); 951 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 952 return ICmpInst::getSwappedPredicate(SwappedRelation); 953 else 954 return ICmpInst::BAD_ICMP_PREDICATE; 955 } 956 957 // Now we know that the RHS is a GlobalValue or simple constant, 958 // which (since the types must match) means that it's a ConstantPointerNull. 959 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) { 960 // Don't try to decide equality of aliases. 961 if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2)) 962 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage()) 963 return ICmpInst::ICMP_NE; 964 } else { 965 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); 966 // GlobalVals can never be null. Don't try to evaluate aliases. 967 if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1)) 968 return ICmpInst::ICMP_NE; 969 } 970 } else { 971 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 972 // constantexpr, a CPR, or a simple constant. 973 const ConstantExpr *CE1 = cast<ConstantExpr>(V1); 974 const Constant *CE1Op0 = CE1->getOperand(0); 975 976 switch (CE1->getOpcode()) { 977 case Instruction::Trunc: 978 case Instruction::FPTrunc: 979 case Instruction::FPExt: 980 case Instruction::FPToUI: 981 case Instruction::FPToSI: 982 break; // We can't evaluate floating point casts or truncations. 983 984 case Instruction::UIToFP: 985 case Instruction::SIToFP: 986 case Instruction::BitCast: 987 case Instruction::ZExt: 988 case Instruction::SExt: 989 // If the cast is not actually changing bits, and the second operand is a 990 // null pointer, do the comparison with the pre-casted value. 991 if (V2->isNullValue() && 992 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) { 993 bool sgnd = isSigned; 994 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 995 if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 996 return evaluateICmpRelation(CE1Op0, 997 Constant::getNullValue(CE1Op0->getType()), 998 sgnd); 999 } 1000 1001 // If the dest type is a pointer type, and the RHS is a constantexpr cast 1002 // from the same type as the src of the LHS, evaluate the inputs. This is 1003 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)", 1004 // which happens a lot in compilers with tagged integers. 1005 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) 1006 if (CE2->isCast() && isa<PointerType>(CE1->getType()) && 1007 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() && 1008 CE1->getOperand(0)->getType()->isInteger()) { 1009 bool sgnd = isSigned; 1010 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 1011 if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 1012 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0), 1013 sgnd); 1014 } 1015 break; 1016 1017 case Instruction::GetElementPtr: 1018 // Ok, since this is a getelementptr, we know that the constant has a 1019 // pointer type. Check the various cases. 1020 if (isa<ConstantPointerNull>(V2)) { 1021 // If we are comparing a GEP to a null pointer, check to see if the base 1022 // of the GEP equals the null pointer. 1023 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1024 if (GV->hasExternalWeakLinkage()) 1025 // Weak linkage GVals could be zero or not. We're comparing that 1026 // to null pointer so its greater-or-equal 1027 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; 1028 else 1029 // If its not weak linkage, the GVal must have a non-zero address 1030 // so the result is greater-than 1031 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1032 } else if (isa<ConstantPointerNull>(CE1Op0)) { 1033 // If we are indexing from a null pointer, check to see if we have any 1034 // non-zero indices. 1035 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) 1036 if (!CE1->getOperand(i)->isNullValue()) 1037 // Offsetting from null, must not be equal. 1038 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1039 // Only zero indexes from null, must still be zero. 1040 return ICmpInst::ICMP_EQ; 1041 } 1042 // Otherwise, we can't really say if the first operand is null or not. 1043 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) { 1044 if (isa<ConstantPointerNull>(CE1Op0)) { 1045 if (CPR2->hasExternalWeakLinkage()) 1046 // Weak linkage GVals could be zero or not. We're comparing it to 1047 // a null pointer, so its less-or-equal 1048 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; 1049 else 1050 // If its not weak linkage, the GVal must have a non-zero address 1051 // so the result is less-than 1052 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1053 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) { 1054 if (CPR1 == CPR2) { 1055 // If this is a getelementptr of the same global, then it must be 1056 // different. Because the types must match, the getelementptr could 1057 // only have at most one index, and because we fold getelementptr's 1058 // with a single zero index, it must be nonzero. 1059 assert(CE1->getNumOperands() == 2 && 1060 !CE1->getOperand(1)->isNullValue() && 1061 "Suprising getelementptr!"); 1062 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1063 } else { 1064 // If they are different globals, we don't know what the value is, 1065 // but they can't be equal. 1066 return ICmpInst::ICMP_NE; 1067 } 1068 } 1069 } else { 1070 const ConstantExpr *CE2 = cast<ConstantExpr>(V2); 1071 const Constant *CE2Op0 = CE2->getOperand(0); 1072 1073 // There are MANY other foldings that we could perform here. They will 1074 // probably be added on demand, as they seem needed. 1075 switch (CE2->getOpcode()) { 1076 default: break; 1077 case Instruction::GetElementPtr: 1078 // By far the most common case to handle is when the base pointers are 1079 // obviously to the same or different globals. 1080 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { 1081 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal 1082 return ICmpInst::ICMP_NE; 1083 // Ok, we know that both getelementptr instructions are based on the 1084 // same global. From this, we can precisely determine the relative 1085 // ordering of the resultant pointers. 1086 unsigned i = 1; 1087 1088 // Compare all of the operands the GEP's have in common. 1089 gep_type_iterator GTI = gep_type_begin(CE1); 1090 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); 1091 ++i, ++GTI) 1092 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i), 1093 GTI.getIndexedType())) { 1094 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; 1095 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; 1096 case -2: return ICmpInst::BAD_ICMP_PREDICATE; 1097 } 1098 1099 // Ok, we ran out of things they have in common. If any leftovers 1100 // are non-zero then we have a difference, otherwise we are equal. 1101 for (; i < CE1->getNumOperands(); ++i) 1102 if (!CE1->getOperand(i)->isNullValue()) { 1103 if (isa<ConstantInt>(CE1->getOperand(i))) 1104 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1105 else 1106 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1107 } 1108 1109 for (; i < CE2->getNumOperands(); ++i) 1110 if (!CE2->getOperand(i)->isNullValue()) { 1111 if (isa<ConstantInt>(CE2->getOperand(i))) 1112 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1113 else 1114 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1115 } 1116 return ICmpInst::ICMP_EQ; 1117 } 1118 } 1119 } 1120 default: 1121 break; 1122 } 1123 } 1124 1125 return ICmpInst::BAD_ICMP_PREDICATE; 1126} 1127 1128Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred, 1129 const Constant *C1, 1130 const Constant *C2) { 1131 1132 // Handle some degenerate cases first 1133 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) 1134 return UndefValue::get(Type::Int1Ty); 1135 1136 // No compile-time operations on this type yet. 1137 if (C1->getType() == Type::PPC_FP128Ty) 1138 return 0; 1139 1140 // icmp eq/ne(null,GV) -> false/true 1141 if (C1->isNullValue()) { 1142 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) 1143 // Don't try to evaluate aliases. External weak GV can be null. 1144 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1145 if (pred == ICmpInst::ICMP_EQ) 1146 return ConstantInt::getFalse(); 1147 else if (pred == ICmpInst::ICMP_NE) 1148 return ConstantInt::getTrue(); 1149 } 1150 // icmp eq/ne(GV,null) -> false/true 1151 } else if (C2->isNullValue()) { 1152 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) 1153 // Don't try to evaluate aliases. External weak GV can be null. 1154 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1155 if (pred == ICmpInst::ICMP_EQ) 1156 return ConstantInt::getFalse(); 1157 else if (pred == ICmpInst::ICMP_NE) 1158 return ConstantInt::getTrue(); 1159 } 1160 } 1161 1162 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { 1163 APInt V1 = cast<ConstantInt>(C1)->getValue(); 1164 APInt V2 = cast<ConstantInt>(C2)->getValue(); 1165 switch (pred) { 1166 default: assert(0 && "Invalid ICmp Predicate"); return 0; 1167 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2); 1168 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2); 1169 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2)); 1170 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2)); 1171 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2)); 1172 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2)); 1173 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2)); 1174 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2)); 1175 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2)); 1176 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2)); 1177 } 1178 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { 1179 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); 1180 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); 1181 APFloat::cmpResult R = C1V.compare(C2V); 1182 switch (pred) { 1183 default: assert(0 && "Invalid FCmp Predicate"); return 0; 1184 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse(); 1185 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue(); 1186 case FCmpInst::FCMP_UNO: 1187 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered); 1188 case FCmpInst::FCMP_ORD: 1189 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpUnordered); 1190 case FCmpInst::FCMP_UEQ: 1191 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered || 1192 R==APFloat::cmpEqual); 1193 case FCmpInst::FCMP_OEQ: 1194 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpEqual); 1195 case FCmpInst::FCMP_UNE: 1196 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpEqual); 1197 case FCmpInst::FCMP_ONE: 1198 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan || 1199 R==APFloat::cmpGreaterThan); 1200 case FCmpInst::FCMP_ULT: 1201 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered || 1202 R==APFloat::cmpLessThan); 1203 case FCmpInst::FCMP_OLT: 1204 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan); 1205 case FCmpInst::FCMP_UGT: 1206 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered || 1207 R==APFloat::cmpGreaterThan); 1208 case FCmpInst::FCMP_OGT: 1209 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan); 1210 case FCmpInst::FCMP_ULE: 1211 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpGreaterThan); 1212 case FCmpInst::FCMP_OLE: 1213 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan || 1214 R==APFloat::cmpEqual); 1215 case FCmpInst::FCMP_UGE: 1216 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpLessThan); 1217 case FCmpInst::FCMP_OGE: 1218 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan || 1219 R==APFloat::cmpEqual); 1220 } 1221 } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) { 1222 if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) { 1223 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) { 1224 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) { 1225 Constant *C= ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, 1226 const_cast<Constant*>(CP1->getOperand(i)), 1227 const_cast<Constant*>(CP2->getOperand(i))); 1228 if (ConstantInt *CB = dyn_cast<ConstantInt>(C)) 1229 return CB; 1230 } 1231 // Otherwise, could not decide from any element pairs. 1232 return 0; 1233 } else if (pred == ICmpInst::ICMP_EQ) { 1234 for (unsigned i = 0, e = CP1->getNumOperands(); i != e; ++i) { 1235 Constant *C = ConstantExpr::getICmp(ICmpInst::ICMP_EQ, 1236 const_cast<Constant*>(CP1->getOperand(i)), 1237 const_cast<Constant*>(CP2->getOperand(i))); 1238 if (ConstantInt *CB = dyn_cast<ConstantInt>(C)) 1239 return CB; 1240 } 1241 // Otherwise, could not decide from any element pairs. 1242 return 0; 1243 } 1244 } 1245 } 1246 1247 if (C1->getType()->isFloatingPoint()) { 1248 switch (evaluateFCmpRelation(C1, C2)) { 1249 default: assert(0 && "Unknown relation!"); 1250 case FCmpInst::FCMP_UNO: 1251 case FCmpInst::FCMP_ORD: 1252 case FCmpInst::FCMP_UEQ: 1253 case FCmpInst::FCMP_UNE: 1254 case FCmpInst::FCMP_ULT: 1255 case FCmpInst::FCMP_UGT: 1256 case FCmpInst::FCMP_ULE: 1257 case FCmpInst::FCMP_UGE: 1258 case FCmpInst::FCMP_TRUE: 1259 case FCmpInst::FCMP_FALSE: 1260 case FCmpInst::BAD_FCMP_PREDICATE: 1261 break; // Couldn't determine anything about these constants. 1262 case FCmpInst::FCMP_OEQ: // We know that C1 == C2 1263 return ConstantInt::get(Type::Int1Ty, 1264 pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || 1265 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || 1266 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1267 case FCmpInst::FCMP_OLT: // We know that C1 < C2 1268 return ConstantInt::get(Type::Int1Ty, 1269 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1270 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || 1271 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); 1272 case FCmpInst::FCMP_OGT: // We know that C1 > C2 1273 return ConstantInt::get(Type::Int1Ty, 1274 pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1275 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || 1276 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1277 case FCmpInst::FCMP_OLE: // We know that C1 <= C2 1278 // We can only partially decide this relation. 1279 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1280 return ConstantInt::getFalse(); 1281 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1282 return ConstantInt::getTrue(); 1283 break; 1284 case FCmpInst::FCMP_OGE: // We known that C1 >= C2 1285 // We can only partially decide this relation. 1286 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1287 return ConstantInt::getFalse(); 1288 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1289 return ConstantInt::getTrue(); 1290 break; 1291 case ICmpInst::ICMP_NE: // We know that C1 != C2 1292 // We can only partially decide this relation. 1293 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) 1294 return ConstantInt::getFalse(); 1295 if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) 1296 return ConstantInt::getTrue(); 1297 break; 1298 } 1299 } else { 1300 // Evaluate the relation between the two constants, per the predicate. 1301 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) { 1302 default: assert(0 && "Unknown relational!"); 1303 case ICmpInst::BAD_ICMP_PREDICATE: 1304 break; // Couldn't determine anything about these constants. 1305 case ICmpInst::ICMP_EQ: // We know the constants are equal! 1306 // If we know the constants are equal, we can decide the result of this 1307 // computation precisely. 1308 return ConstantInt::get(Type::Int1Ty, 1309 pred == ICmpInst::ICMP_EQ || 1310 pred == ICmpInst::ICMP_ULE || 1311 pred == ICmpInst::ICMP_SLE || 1312 pred == ICmpInst::ICMP_UGE || 1313 pred == ICmpInst::ICMP_SGE); 1314 case ICmpInst::ICMP_ULT: 1315 // If we know that C1 < C2, we can decide the result of this computation 1316 // precisely. 1317 return ConstantInt::get(Type::Int1Ty, 1318 pred == ICmpInst::ICMP_ULT || 1319 pred == ICmpInst::ICMP_NE || 1320 pred == ICmpInst::ICMP_ULE); 1321 case ICmpInst::ICMP_SLT: 1322 // If we know that C1 < C2, we can decide the result of this computation 1323 // precisely. 1324 return ConstantInt::get(Type::Int1Ty, 1325 pred == ICmpInst::ICMP_SLT || 1326 pred == ICmpInst::ICMP_NE || 1327 pred == ICmpInst::ICMP_SLE); 1328 case ICmpInst::ICMP_UGT: 1329 // If we know that C1 > C2, we can decide the result of this computation 1330 // precisely. 1331 return ConstantInt::get(Type::Int1Ty, 1332 pred == ICmpInst::ICMP_UGT || 1333 pred == ICmpInst::ICMP_NE || 1334 pred == ICmpInst::ICMP_UGE); 1335 case ICmpInst::ICMP_SGT: 1336 // If we know that C1 > C2, we can decide the result of this computation 1337 // precisely. 1338 return ConstantInt::get(Type::Int1Ty, 1339 pred == ICmpInst::ICMP_SGT || 1340 pred == ICmpInst::ICMP_NE || 1341 pred == ICmpInst::ICMP_SGE); 1342 case ICmpInst::ICMP_ULE: 1343 // If we know that C1 <= C2, we can only partially decide this relation. 1344 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getFalse(); 1345 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getTrue(); 1346 break; 1347 case ICmpInst::ICMP_SLE: 1348 // If we know that C1 <= C2, we can only partially decide this relation. 1349 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getFalse(); 1350 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getTrue(); 1351 break; 1352 1353 case ICmpInst::ICMP_UGE: 1354 // If we know that C1 >= C2, we can only partially decide this relation. 1355 if (pred == ICmpInst::ICMP_ULT) return ConstantInt::getFalse(); 1356 if (pred == ICmpInst::ICMP_UGT) return ConstantInt::getTrue(); 1357 break; 1358 case ICmpInst::ICMP_SGE: 1359 // If we know that C1 >= C2, we can only partially decide this relation. 1360 if (pred == ICmpInst::ICMP_SLT) return ConstantInt::getFalse(); 1361 if (pred == ICmpInst::ICMP_SGT) return ConstantInt::getTrue(); 1362 break; 1363 1364 case ICmpInst::ICMP_NE: 1365 // If we know that C1 != C2, we can only partially decide this relation. 1366 if (pred == ICmpInst::ICMP_EQ) return ConstantInt::getFalse(); 1367 if (pred == ICmpInst::ICMP_NE) return ConstantInt::getTrue(); 1368 break; 1369 } 1370 1371 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) { 1372 // If C2 is a constant expr and C1 isn't, flop them around and fold the 1373 // other way if possible. 1374 switch (pred) { 1375 case ICmpInst::ICMP_EQ: 1376 case ICmpInst::ICMP_NE: 1377 // No change of predicate required. 1378 return ConstantFoldCompareInstruction(pred, C2, C1); 1379 1380 case ICmpInst::ICMP_ULT: 1381 case ICmpInst::ICMP_SLT: 1382 case ICmpInst::ICMP_UGT: 1383 case ICmpInst::ICMP_SGT: 1384 case ICmpInst::ICMP_ULE: 1385 case ICmpInst::ICMP_SLE: 1386 case ICmpInst::ICMP_UGE: 1387 case ICmpInst::ICMP_SGE: 1388 // Change the predicate as necessary to swap the operands. 1389 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); 1390 return ConstantFoldCompareInstruction(pred, C2, C1); 1391 1392 default: // These predicates cannot be flopped around. 1393 break; 1394 } 1395 } 1396 } 1397 return 0; 1398} 1399 1400Constant *llvm::ConstantFoldGetElementPtr(const Constant *C, 1401 Constant* const *Idxs, 1402 unsigned NumIdx) { 1403 if (NumIdx == 0 || 1404 (NumIdx == 1 && Idxs[0]->isNullValue())) 1405 return const_cast<Constant*>(C); 1406 1407 if (isa<UndefValue>(C)) { 1408 const PointerType *Ptr = cast<PointerType>(C->getType()); 1409 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr, 1410 (Value **)Idxs, 1411 (Value **)Idxs+NumIdx, 1412 true); 1413 assert(Ty != 0 && "Invalid indices for GEP!"); 1414 return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); 1415 } 1416 1417 Constant *Idx0 = Idxs[0]; 1418 if (C->isNullValue()) { 1419 bool isNull = true; 1420 for (unsigned i = 0, e = NumIdx; i != e; ++i) 1421 if (!Idxs[i]->isNullValue()) { 1422 isNull = false; 1423 break; 1424 } 1425 if (isNull) { 1426 const PointerType *Ptr = cast<PointerType>(C->getType()); 1427 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr, 1428 (Value**)Idxs, 1429 (Value**)Idxs+NumIdx, 1430 true); 1431 assert(Ty != 0 && "Invalid indices for GEP!"); 1432 return 1433 ConstantPointerNull::get(PointerType::get(Ty,Ptr->getAddressSpace())); 1434 } 1435 } 1436 1437 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) { 1438 // Combine Indices - If the source pointer to this getelementptr instruction 1439 // is a getelementptr instruction, combine the indices of the two 1440 // getelementptr instructions into a single instruction. 1441 // 1442 if (CE->getOpcode() == Instruction::GetElementPtr) { 1443 const Type *LastTy = 0; 1444 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); 1445 I != E; ++I) 1446 LastTy = *I; 1447 1448 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) { 1449 SmallVector<Value*, 16> NewIndices; 1450 NewIndices.reserve(NumIdx + CE->getNumOperands()); 1451 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) 1452 NewIndices.push_back(CE->getOperand(i)); 1453 1454 // Add the last index of the source with the first index of the new GEP. 1455 // Make sure to handle the case when they are actually different types. 1456 Constant *Combined = CE->getOperand(CE->getNumOperands()-1); 1457 // Otherwise it must be an array. 1458 if (!Idx0->isNullValue()) { 1459 const Type *IdxTy = Combined->getType(); 1460 if (IdxTy != Idx0->getType()) { 1461 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty); 1462 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, 1463 Type::Int64Ty); 1464 Combined = ConstantExpr::get(Instruction::Add, C1, C2); 1465 } else { 1466 Combined = 1467 ConstantExpr::get(Instruction::Add, Idx0, Combined); 1468 } 1469 } 1470 1471 NewIndices.push_back(Combined); 1472 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx); 1473 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0], 1474 NewIndices.size()); 1475 } 1476 } 1477 1478 // Implement folding of: 1479 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*), 1480 // long 0, long 0) 1481 // To: int* getelementptr ([3 x int]* %X, long 0, long 0) 1482 // 1483 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) { 1484 if (const PointerType *SPT = 1485 dyn_cast<PointerType>(CE->getOperand(0)->getType())) 1486 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType())) 1487 if (const ArrayType *CAT = 1488 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType())) 1489 if (CAT->getElementType() == SAT->getElementType()) 1490 return ConstantExpr::getGetElementPtr( 1491 (Constant*)CE->getOperand(0), Idxs, NumIdx); 1492 } 1493 1494 // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1) 1495 // Into: inttoptr (i64 0 to i8*) 1496 // This happens with pointers to member functions in C++. 1497 if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 && 1498 isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) && 1499 cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) { 1500 Constant *Base = CE->getOperand(0); 1501 Constant *Offset = Idxs[0]; 1502 1503 // Convert the smaller integer to the larger type. 1504 if (Offset->getType()->getPrimitiveSizeInBits() < 1505 Base->getType()->getPrimitiveSizeInBits()) 1506 Offset = ConstantExpr::getSExt(Offset, Base->getType()); 1507 else if (Base->getType()->getPrimitiveSizeInBits() < 1508 Offset->getType()->getPrimitiveSizeInBits()) 1509 Base = ConstantExpr::getZExt(Base, Base->getType()); 1510 1511 Base = ConstantExpr::getAdd(Base, Offset); 1512 return ConstantExpr::getIntToPtr(Base, CE->getType()); 1513 } 1514 } 1515 return 0; 1516} 1517 1518