ConstantFold.cpp revision 8c65f6e71c1d46d823b9a884819992a9255edd54
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// pieces that don't need TargetData, and the pieces that do. This is to avoid 16// a dependence in VMCore on Target. 17// 18//===----------------------------------------------------------------------===// 19 20#include "ConstantFold.h" 21#include "llvm/Constants.h" 22#include "llvm/Instructions.h" 23#include "llvm/DerivedTypes.h" 24#include "llvm/Function.h" 25#include "llvm/GlobalAlias.h" 26#include "llvm/GlobalVariable.h" 27#include "llvm/LLVMContext.h" 28#include "llvm/ADT/SmallVector.h" 29#include "llvm/Support/Compiler.h" 30#include "llvm/Support/ErrorHandling.h" 31#include "llvm/Support/GetElementPtrTypeIterator.h" 32#include "llvm/Support/ManagedStatic.h" 33#include "llvm/Support/MathExtras.h" 34#include <limits> 35using namespace llvm; 36 37//===----------------------------------------------------------------------===// 38// ConstantFold*Instruction Implementations 39//===----------------------------------------------------------------------===// 40 41/// BitCastConstantVector - Convert the specified ConstantVector node to the 42/// specified vector type. At this point, we know that the elements of the 43/// input vector constant are all simple integer or FP values. 44static Constant *BitCastConstantVector(LLVMContext &Context, ConstantVector *CV, 45 const VectorType *DstTy) { 46 // If this cast changes element count then we can't handle it here: 47 // doing so requires endianness information. This should be handled by 48 // Analysis/ConstantFolding.cpp 49 unsigned NumElts = DstTy->getNumElements(); 50 if (NumElts != CV->getNumOperands()) 51 return 0; 52 53 // Check to verify that all elements of the input are simple. 54 for (unsigned i = 0; i != NumElts; ++i) { 55 if (!isa<ConstantInt>(CV->getOperand(i)) && 56 !isa<ConstantFP>(CV->getOperand(i))) 57 return 0; 58 } 59 60 // Bitcast each element now. 61 std::vector<Constant*> Result; 62 const Type *DstEltTy = DstTy->getElementType(); 63 for (unsigned i = 0; i != NumElts; ++i) 64 Result.push_back(ConstantExpr::getBitCast(CV->getOperand(i), 65 DstEltTy)); 66 return ConstantVector::get(Result); 67} 68 69/// This function determines which opcode to use to fold two constant cast 70/// expressions together. It uses CastInst::isEliminableCastPair to determine 71/// the opcode. Consequently its just a wrapper around that function. 72/// @brief Determine if it is valid to fold a cast of a cast 73static unsigned 74foldConstantCastPair( 75 unsigned opc, ///< opcode of the second cast constant expression 76 ConstantExpr *Op, ///< the first cast constant expression 77 const Type *DstTy ///< desintation type of the first cast 78) { 79 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!"); 80 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type"); 81 assert(CastInst::isCast(opc) && "Invalid cast opcode"); 82 83 // The the types and opcodes for the two Cast constant expressions 84 const Type *SrcTy = Op->getOperand(0)->getType(); 85 const Type *MidTy = Op->getType(); 86 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode()); 87 Instruction::CastOps secondOp = Instruction::CastOps(opc); 88 89 // Let CastInst::isEliminableCastPair do the heavy lifting. 90 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy, 91 Type::getInt64Ty(DstTy->getContext())); 92} 93 94static Constant *FoldBitCast(LLVMContext &Context, 95 Constant *V, const Type *DestTy) { 96 const Type *SrcTy = V->getType(); 97 if (SrcTy == DestTy) 98 return V; // no-op cast 99 100 // Check to see if we are casting a pointer to an aggregate to a pointer to 101 // the first element. If so, return the appropriate GEP instruction. 102 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) 103 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) 104 if (PTy->getAddressSpace() == DPTy->getAddressSpace()) { 105 SmallVector<Value*, 8> IdxList; 106 Value *Zero = Constant::getNullValue(Type::getInt32Ty(Context)); 107 IdxList.push_back(Zero); 108 const Type *ElTy = PTy->getElementType(); 109 while (ElTy != DPTy->getElementType()) { 110 if (const StructType *STy = dyn_cast<StructType>(ElTy)) { 111 if (STy->getNumElements() == 0) break; 112 ElTy = STy->getElementType(0); 113 IdxList.push_back(Zero); 114 } else if (const SequentialType *STy = 115 dyn_cast<SequentialType>(ElTy)) { 116 if (isa<PointerType>(ElTy)) break; // Can't index into pointers! 117 ElTy = STy->getElementType(); 118 IdxList.push_back(Zero); 119 } else { 120 break; 121 } 122 } 123 124 if (ElTy == DPTy->getElementType()) 125 // This GEP is inbounds because all indices are zero. 126 return ConstantExpr::getInBoundsGetElementPtr(V, &IdxList[0], 127 IdxList.size()); 128 } 129 130 // Handle casts from one vector constant to another. We know that the src 131 // and dest type have the same size (otherwise its an illegal cast). 132 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { 133 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { 134 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && 135 "Not cast between same sized vectors!"); 136 SrcTy = NULL; 137 // First, check for null. Undef is already handled. 138 if (isa<ConstantAggregateZero>(V)) 139 return Constant::getNullValue(DestTy); 140 141 if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) 142 return BitCastConstantVector(Context, CV, DestPTy); 143 } 144 145 // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts 146 // This allows for other simplifications (although some of them 147 // can only be handled by Analysis/ConstantFolding.cpp). 148 if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) 149 return ConstantExpr::getBitCast( 150 ConstantVector::get(&V, 1), DestPTy); 151 } 152 153 // Finally, implement bitcast folding now. The code below doesn't handle 154 // bitcast right. 155 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. 156 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 157 158 // Handle integral constant input. 159 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 160 if (DestTy->isInteger()) 161 // Integral -> Integral. This is a no-op because the bit widths must 162 // be the same. Consequently, we just fold to V. 163 return V; 164 165 if (DestTy->isFloatingPoint()) 166 return ConstantFP::get(Context, APFloat(CI->getValue(), 167 DestTy != Type::getPPC_FP128Ty(Context))); 168 169 // Otherwise, can't fold this (vector?) 170 return 0; 171 } 172 173 // Handle ConstantFP input. 174 if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) 175 // FP -> Integral. 176 return ConstantInt::get(Context, FP->getValueAPF().bitcastToAPInt()); 177 178 return 0; 179} 180 181 182/// ExtractConstantBytes - V is an integer constant which only has a subset of 183/// its bytes used. The bytes used are indicated by ByteStart (which is the 184/// first byte used, counting from the least significant byte) and ByteSize, 185/// which is the number of bytes used. 186/// 187/// This function analyzes the specified constant to see if the specified byte 188/// range can be returned as a simplified constant. If so, the constant is 189/// returned, otherwise null is returned. 190/// 191static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, 192 unsigned ByteSize) { 193 assert(isa<IntegerType>(C->getType()) && 194 (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 && 195 "Non-byte sized integer input"); 196 unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; 197 assert(ByteSize && "Must be accessing some piece"); 198 assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input"); 199 assert(ByteSize != CSize && "Should not extract everything"); 200 201 // Constant Integers are simple. 202 if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { 203 APInt V = CI->getValue(); 204 if (ByteStart) 205 V = V.lshr(ByteStart*8); 206 V.trunc(ByteSize*8); 207 return ConstantInt::get(CI->getContext(), V); 208 } 209 210 // In the input is a constant expr, we might be able to recursively simplify. 211 // If not, we definitely can't do anything. 212 ConstantExpr *CE = dyn_cast<ConstantExpr>(C); 213 if (CE == 0) return 0; 214 215 switch (CE->getOpcode()) { 216 default: return 0; 217 case Instruction::Or: { 218 Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 219 if (RHS == 0) 220 return 0; 221 222 // X | -1 -> -1. 223 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) 224 if (RHSC->isAllOnesValue()) 225 return RHSC; 226 227 Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 228 if (LHS == 0) 229 return 0; 230 return ConstantExpr::getOr(LHS, RHS); 231 } 232 case Instruction::And: { 233 Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 234 if (RHS == 0) 235 return 0; 236 237 // X & 0 -> 0. 238 if (RHS->isNullValue()) 239 return RHS; 240 241 Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 242 if (LHS == 0) 243 return 0; 244 return ConstantExpr::getAnd(LHS, RHS); 245 } 246 case Instruction::LShr: { 247 ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 248 if (Amt == 0) 249 return 0; 250 unsigned ShAmt = Amt->getZExtValue(); 251 // Cannot analyze non-byte shifts. 252 if ((ShAmt & 7) != 0) 253 return 0; 254 ShAmt >>= 3; 255 256 // If the extract is known to be all zeros, return zero. 257 if (ByteStart >= CSize-ShAmt) 258 return Constant::getNullValue(IntegerType::get(CE->getContext(), 259 ByteSize*8)); 260 // If the extract is known to be fully in the input, extract it. 261 if (ByteStart+ByteSize+ShAmt <= CSize) 262 return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize); 263 264 // TODO: Handle the 'partially zero' case. 265 return 0; 266 } 267 268 case Instruction::Shl: { 269 ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 270 if (Amt == 0) 271 return 0; 272 unsigned ShAmt = Amt->getZExtValue(); 273 // Cannot analyze non-byte shifts. 274 if ((ShAmt & 7) != 0) 275 return 0; 276 ShAmt >>= 3; 277 278 // If the extract is known to be all zeros, return zero. 279 if (ByteStart+ByteSize <= ShAmt) 280 return Constant::getNullValue(IntegerType::get(CE->getContext(), 281 ByteSize*8)); 282 // If the extract is known to be fully in the input, extract it. 283 if (ByteStart >= ShAmt) 284 return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize); 285 286 // TODO: Handle the 'partially zero' case. 287 return 0; 288 } 289 290 case Instruction::ZExt: { 291 unsigned SrcBitSize = 292 cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth(); 293 294 // If extracting something that is completely zero, return 0. 295 if (ByteStart*8 >= SrcBitSize) 296 return Constant::getNullValue(IntegerType::get(CE->getContext(), 297 ByteSize*8)); 298 299 // If exactly extracting the input, return it. 300 if (ByteStart == 0 && ByteSize*8 == SrcBitSize) 301 return CE->getOperand(0); 302 303 // If extracting something completely in the input, if if the input is a 304 // multiple of 8 bits, recurse. 305 if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize) 306 return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize); 307 308 // Otherwise, if extracting a subset of the input, which is not multiple of 309 // 8 bits, do a shift and trunc to get the bits. 310 if ((ByteStart+ByteSize)*8 < SrcBitSize) { 311 assert((SrcBitSize&7) && "Shouldn't get byte sized case here"); 312 Constant *Res = CE->getOperand(0); 313 if (ByteStart) 314 Res = ConstantExpr::getLShr(Res, 315 ConstantInt::get(Res->getType(), ByteStart*8)); 316 return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(), 317 ByteSize*8)); 318 } 319 320 // TODO: Handle the 'partially zero' case. 321 return 0; 322 } 323 } 324} 325 326 327Constant *llvm::ConstantFoldCastInstruction(LLVMContext &Context, 328 unsigned opc, Constant *V, 329 const Type *DestTy) { 330 if (isa<UndefValue>(V)) { 331 // zext(undef) = 0, because the top bits will be zero. 332 // sext(undef) = 0, because the top bits will all be the same. 333 // [us]itofp(undef) = 0, because the result value is bounded. 334 if (opc == Instruction::ZExt || opc == Instruction::SExt || 335 opc == Instruction::UIToFP || opc == Instruction::SIToFP) 336 return Constant::getNullValue(DestTy); 337 return UndefValue::get(DestTy); 338 } 339 // No compile-time operations on this type yet. 340 if (V->getType()->isPPC_FP128Ty() || DestTy->isPPC_FP128Ty()) 341 return 0; 342 343 // If the cast operand is a constant expression, there's a few things we can 344 // do to try to simplify it. 345 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 346 if (CE->isCast()) { 347 // Try hard to fold cast of cast because they are often eliminable. 348 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) 349 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); 350 } else if (CE->getOpcode() == Instruction::GetElementPtr) { 351 // If all of the indexes in the GEP are null values, there is no pointer 352 // adjustment going on. We might as well cast the source pointer. 353 bool isAllNull = true; 354 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) 355 if (!CE->getOperand(i)->isNullValue()) { 356 isAllNull = false; 357 break; 358 } 359 if (isAllNull) 360 // This is casting one pointer type to another, always BitCast 361 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); 362 } 363 } 364 365 // If the cast operand is a constant vector, perform the cast by 366 // operating on each element. In the cast of bitcasts, the element 367 // count may be mismatched; don't attempt to handle that here. 368 if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) 369 if (isa<VectorType>(DestTy) && 370 cast<VectorType>(DestTy)->getNumElements() == 371 CV->getType()->getNumElements()) { 372 std::vector<Constant*> res; 373 const VectorType *DestVecTy = cast<VectorType>(DestTy); 374 const Type *DstEltTy = DestVecTy->getElementType(); 375 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) 376 res.push_back(ConstantExpr::getCast(opc, 377 CV->getOperand(i), DstEltTy)); 378 return ConstantVector::get(DestVecTy, res); 379 } 380 381 // We actually have to do a cast now. Perform the cast according to the 382 // opcode specified. 383 switch (opc) { 384 default: 385 llvm_unreachable("Failed to cast constant expression"); 386 case Instruction::FPTrunc: 387 case Instruction::FPExt: 388 if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 389 bool ignored; 390 APFloat Val = FPC->getValueAPF(); 391 Val.convert(DestTy->isFloatTy() ? APFloat::IEEEsingle : 392 DestTy->isDoubleTy() ? APFloat::IEEEdouble : 393 DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended : 394 DestTy->isFP128Ty() ? APFloat::IEEEquad : 395 APFloat::Bogus, 396 APFloat::rmNearestTiesToEven, &ignored); 397 return ConstantFP::get(Context, Val); 398 } 399 return 0; // Can't fold. 400 case Instruction::FPToUI: 401 case Instruction::FPToSI: 402 if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 403 const APFloat &V = FPC->getValueAPF(); 404 bool ignored; 405 uint64_t x[2]; 406 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 407 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, 408 APFloat::rmTowardZero, &ignored); 409 APInt Val(DestBitWidth, 2, x); 410 return ConstantInt::get(Context, Val); 411 } 412 return 0; // Can't fold. 413 case Instruction::IntToPtr: //always treated as unsigned 414 if (V->isNullValue()) // Is it an integral null value? 415 return ConstantPointerNull::get(cast<PointerType>(DestTy)); 416 return 0; // Other pointer types cannot be casted 417 case Instruction::PtrToInt: // always treated as unsigned 418 if (V->isNullValue()) // is it a null pointer value? 419 return ConstantInt::get(DestTy, 0); 420 return 0; // Other pointer types cannot be casted 421 case Instruction::UIToFP: 422 case Instruction::SIToFP: 423 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 424 APInt api = CI->getValue(); 425 const uint64_t zero[] = {0, 0}; 426 APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(), 427 2, zero)); 428 (void)apf.convertFromAPInt(api, 429 opc==Instruction::SIToFP, 430 APFloat::rmNearestTiesToEven); 431 return ConstantFP::get(Context, apf); 432 } 433 return 0; 434 case Instruction::ZExt: 435 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 436 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 437 APInt Result(CI->getValue()); 438 Result.zext(BitWidth); 439 return ConstantInt::get(Context, Result); 440 } 441 return 0; 442 case Instruction::SExt: 443 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 444 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 445 APInt Result(CI->getValue()); 446 Result.sext(BitWidth); 447 return ConstantInt::get(Context, Result); 448 } 449 return 0; 450 case Instruction::Trunc: { 451 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 452 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 453 APInt Result(CI->getValue()); 454 Result.trunc(DestBitWidth); 455 return ConstantInt::get(Context, Result); 456 } 457 458 // The input must be a constantexpr. See if we can simplify this based on 459 // the bytes we are demanding. Only do this if the source and dest are an 460 // even multiple of a byte. 461 if ((DestBitWidth & 7) == 0 && 462 (cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0) 463 if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8)) 464 return Res; 465 466 return 0; 467 } 468 case Instruction::BitCast: 469 return FoldBitCast(Context, V, DestTy); 470 } 471} 472 473Constant *llvm::ConstantFoldSelectInstruction(LLVMContext&, 474 Constant *Cond, 475 Constant *V1, Constant *V2) { 476 if (ConstantInt *CB = dyn_cast<ConstantInt>(Cond)) 477 return CB->getZExtValue() ? V1 : V2; 478 479 if (isa<UndefValue>(V1)) return V2; 480 if (isa<UndefValue>(V2)) return V1; 481 if (isa<UndefValue>(Cond)) return V1; 482 if (V1 == V2) return V1; 483 return 0; 484} 485 486Constant *llvm::ConstantFoldExtractElementInstruction(LLVMContext &Context, 487 Constant *Val, 488 Constant *Idx) { 489 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef 490 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType()); 491 if (Val->isNullValue()) // ee(zero, x) -> zero 492 return Constant::getNullValue( 493 cast<VectorType>(Val->getType())->getElementType()); 494 495 if (ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { 496 if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { 497 return CVal->getOperand(CIdx->getZExtValue()); 498 } else if (isa<UndefValue>(Idx)) { 499 // ee({w,x,y,z}, undef) -> w (an arbitrary value). 500 return CVal->getOperand(0); 501 } 502 } 503 return 0; 504} 505 506Constant *llvm::ConstantFoldInsertElementInstruction(LLVMContext &Context, 507 Constant *Val, 508 Constant *Elt, 509 Constant *Idx) { 510 ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); 511 if (!CIdx) return 0; 512 APInt idxVal = CIdx->getValue(); 513 if (isa<UndefValue>(Val)) { 514 // Insertion of scalar constant into vector undef 515 // Optimize away insertion of undef 516 if (isa<UndefValue>(Elt)) 517 return Val; 518 // Otherwise break the aggregate undef into multiple undefs and do 519 // the insertion 520 unsigned numOps = 521 cast<VectorType>(Val->getType())->getNumElements(); 522 std::vector<Constant*> Ops; 523 Ops.reserve(numOps); 524 for (unsigned i = 0; i < numOps; ++i) { 525 Constant *Op = 526 (idxVal == i) ? Elt : UndefValue::get(Elt->getType()); 527 Ops.push_back(Op); 528 } 529 return ConstantVector::get(Ops); 530 } 531 if (isa<ConstantAggregateZero>(Val)) { 532 // Insertion of scalar constant into vector aggregate zero 533 // Optimize away insertion of zero 534 if (Elt->isNullValue()) 535 return Val; 536 // Otherwise break the aggregate zero into multiple zeros and do 537 // the insertion 538 unsigned numOps = 539 cast<VectorType>(Val->getType())->getNumElements(); 540 std::vector<Constant*> Ops; 541 Ops.reserve(numOps); 542 for (unsigned i = 0; i < numOps; ++i) { 543 Constant *Op = 544 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType()); 545 Ops.push_back(Op); 546 } 547 return ConstantVector::get(Ops); 548 } 549 if (ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { 550 // Insertion of scalar constant into vector constant 551 std::vector<Constant*> Ops; 552 Ops.reserve(CVal->getNumOperands()); 553 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) { 554 Constant *Op = 555 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i)); 556 Ops.push_back(Op); 557 } 558 return ConstantVector::get(Ops); 559 } 560 561 return 0; 562} 563 564/// GetVectorElement - If C is a ConstantVector, ConstantAggregateZero or Undef 565/// return the specified element value. Otherwise return null. 566static Constant *GetVectorElement(LLVMContext &Context, Constant *C, 567 unsigned EltNo) { 568 if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) 569 return CV->getOperand(EltNo); 570 571 const Type *EltTy = cast<VectorType>(C->getType())->getElementType(); 572 if (isa<ConstantAggregateZero>(C)) 573 return Constant::getNullValue(EltTy); 574 if (isa<UndefValue>(C)) 575 return UndefValue::get(EltTy); 576 return 0; 577} 578 579Constant *llvm::ConstantFoldShuffleVectorInstruction(LLVMContext &Context, 580 Constant *V1, 581 Constant *V2, 582 Constant *Mask) { 583 // Undefined shuffle mask -> undefined value. 584 if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType()); 585 586 unsigned MaskNumElts = cast<VectorType>(Mask->getType())->getNumElements(); 587 unsigned SrcNumElts = cast<VectorType>(V1->getType())->getNumElements(); 588 const Type *EltTy = cast<VectorType>(V1->getType())->getElementType(); 589 590 // Loop over the shuffle mask, evaluating each element. 591 SmallVector<Constant*, 32> Result; 592 for (unsigned i = 0; i != MaskNumElts; ++i) { 593 Constant *InElt = GetVectorElement(Context, Mask, i); 594 if (InElt == 0) return 0; 595 596 if (isa<UndefValue>(InElt)) 597 InElt = UndefValue::get(EltTy); 598 else if (ConstantInt *CI = dyn_cast<ConstantInt>(InElt)) { 599 unsigned Elt = CI->getZExtValue(); 600 if (Elt >= SrcNumElts*2) 601 InElt = UndefValue::get(EltTy); 602 else if (Elt >= SrcNumElts) 603 InElt = GetVectorElement(Context, V2, Elt - SrcNumElts); 604 else 605 InElt = GetVectorElement(Context, V1, Elt); 606 if (InElt == 0) return 0; 607 } else { 608 // Unknown value. 609 return 0; 610 } 611 Result.push_back(InElt); 612 } 613 614 return ConstantVector::get(&Result[0], Result.size()); 615} 616 617Constant *llvm::ConstantFoldExtractValueInstruction(LLVMContext &Context, 618 Constant *Agg, 619 const unsigned *Idxs, 620 unsigned NumIdx) { 621 // Base case: no indices, so return the entire value. 622 if (NumIdx == 0) 623 return Agg; 624 625 if (isa<UndefValue>(Agg)) // ev(undef, x) -> undef 626 return UndefValue::get(ExtractValueInst::getIndexedType(Agg->getType(), 627 Idxs, 628 Idxs + NumIdx)); 629 630 if (isa<ConstantAggregateZero>(Agg)) // ev(0, x) -> 0 631 return 632 Constant::getNullValue(ExtractValueInst::getIndexedType(Agg->getType(), 633 Idxs, 634 Idxs + NumIdx)); 635 636 // Otherwise recurse. 637 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Agg)) 638 return ConstantFoldExtractValueInstruction(Context, CS->getOperand(*Idxs), 639 Idxs+1, NumIdx-1); 640 641 if (ConstantArray *CA = dyn_cast<ConstantArray>(Agg)) 642 return ConstantFoldExtractValueInstruction(Context, CA->getOperand(*Idxs), 643 Idxs+1, NumIdx-1); 644 ConstantVector *CV = cast<ConstantVector>(Agg); 645 return ConstantFoldExtractValueInstruction(Context, CV->getOperand(*Idxs), 646 Idxs+1, NumIdx-1); 647} 648 649Constant *llvm::ConstantFoldInsertValueInstruction(LLVMContext &Context, 650 Constant *Agg, 651 Constant *Val, 652 const unsigned *Idxs, 653 unsigned NumIdx) { 654 // Base case: no indices, so replace the entire value. 655 if (NumIdx == 0) 656 return Val; 657 658 if (isa<UndefValue>(Agg)) { 659 // Insertion of constant into aggregate undef 660 // Optimize away insertion of undef. 661 if (isa<UndefValue>(Val)) 662 return Agg; 663 664 // Otherwise break the aggregate undef into multiple undefs and do 665 // the insertion. 666 const CompositeType *AggTy = cast<CompositeType>(Agg->getType()); 667 unsigned numOps; 668 if (const ArrayType *AR = dyn_cast<ArrayType>(AggTy)) 669 numOps = AR->getNumElements(); 670 else 671 numOps = cast<StructType>(AggTy)->getNumElements(); 672 673 std::vector<Constant*> Ops(numOps); 674 for (unsigned i = 0; i < numOps; ++i) { 675 const Type *MemberTy = AggTy->getTypeAtIndex(i); 676 Constant *Op = 677 (*Idxs == i) ? 678 ConstantFoldInsertValueInstruction(Context, UndefValue::get(MemberTy), 679 Val, Idxs+1, NumIdx-1) : 680 UndefValue::get(MemberTy); 681 Ops[i] = Op; 682 } 683 684 if (const StructType* ST = dyn_cast<StructType>(AggTy)) 685 return ConstantStruct::get(Context, Ops, ST->isPacked()); 686 return ConstantArray::get(cast<ArrayType>(AggTy), Ops); 687 } 688 689 if (isa<ConstantAggregateZero>(Agg)) { 690 // Insertion of constant into aggregate zero 691 // Optimize away insertion of zero. 692 if (Val->isNullValue()) 693 return Agg; 694 695 // Otherwise break the aggregate zero into multiple zeros and do 696 // the insertion. 697 const CompositeType *AggTy = cast<CompositeType>(Agg->getType()); 698 unsigned numOps; 699 if (const ArrayType *AR = dyn_cast<ArrayType>(AggTy)) 700 numOps = AR->getNumElements(); 701 else 702 numOps = cast<StructType>(AggTy)->getNumElements(); 703 704 std::vector<Constant*> Ops(numOps); 705 for (unsigned i = 0; i < numOps; ++i) { 706 const Type *MemberTy = AggTy->getTypeAtIndex(i); 707 Constant *Op = 708 (*Idxs == i) ? 709 ConstantFoldInsertValueInstruction(Context, 710 Constant::getNullValue(MemberTy), 711 Val, Idxs+1, NumIdx-1) : 712 Constant::getNullValue(MemberTy); 713 Ops[i] = Op; 714 } 715 716 if (const StructType* ST = dyn_cast<StructType>(AggTy)) 717 return ConstantStruct::get(Context, Ops, ST->isPacked()); 718 return ConstantArray::get(cast<ArrayType>(AggTy), Ops); 719 } 720 721 if (isa<ConstantStruct>(Agg) || isa<ConstantArray>(Agg)) { 722 // Insertion of constant into aggregate constant. 723 std::vector<Constant*> Ops(Agg->getNumOperands()); 724 for (unsigned i = 0; i < Agg->getNumOperands(); ++i) { 725 Constant *Op = cast<Constant>(Agg->getOperand(i)); 726 if (*Idxs == i) 727 Op = ConstantFoldInsertValueInstruction(Context, Op, 728 Val, Idxs+1, NumIdx-1); 729 Ops[i] = Op; 730 } 731 732 if (const StructType* ST = dyn_cast<StructType>(Agg->getType())) 733 return ConstantStruct::get(Context, Ops, ST->isPacked()); 734 return ConstantArray::get(cast<ArrayType>(Agg->getType()), Ops); 735 } 736 737 return 0; 738} 739 740 741Constant *llvm::ConstantFoldBinaryInstruction(LLVMContext &Context, 742 unsigned Opcode, 743 Constant *C1, Constant *C2) { 744 // No compile-time operations on this type yet. 745 if (C1->getType()->isPPC_FP128Ty()) 746 return 0; 747 748 // Handle UndefValue up front. 749 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 750 switch (Opcode) { 751 case Instruction::Xor: 752 if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) 753 // Handle undef ^ undef -> 0 special case. This is a common 754 // idiom (misuse). 755 return Constant::getNullValue(C1->getType()); 756 // Fallthrough 757 case Instruction::Add: 758 case Instruction::Sub: 759 return UndefValue::get(C1->getType()); 760 case Instruction::Mul: 761 case Instruction::And: 762 return Constant::getNullValue(C1->getType()); 763 case Instruction::UDiv: 764 case Instruction::SDiv: 765 case Instruction::URem: 766 case Instruction::SRem: 767 if (!isa<UndefValue>(C2)) // undef / X -> 0 768 return Constant::getNullValue(C1->getType()); 769 return C2; // X / undef -> undef 770 case Instruction::Or: // X | undef -> -1 771 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType())) 772 return Constant::getAllOnesValue(PTy); 773 return Constant::getAllOnesValue(C1->getType()); 774 case Instruction::LShr: 775 if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) 776 return C1; // undef lshr undef -> undef 777 return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 778 // undef lshr X -> 0 779 case Instruction::AShr: 780 if (!isa<UndefValue>(C2)) 781 return C1; // undef ashr X --> undef 782 else if (isa<UndefValue>(C1)) 783 return C1; // undef ashr undef -> undef 784 else 785 return C1; // X ashr undef --> X 786 case Instruction::Shl: 787 // undef << X -> 0 or X << undef -> 0 788 return Constant::getNullValue(C1->getType()); 789 } 790 } 791 792 // Handle simplifications when the RHS is a constant int. 793 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 794 switch (Opcode) { 795 case Instruction::Add: 796 if (CI2->equalsInt(0)) return C1; // X + 0 == X 797 break; 798 case Instruction::Sub: 799 if (CI2->equalsInt(0)) return C1; // X - 0 == X 800 break; 801 case Instruction::Mul: 802 if (CI2->equalsInt(0)) return C2; // X * 0 == 0 803 if (CI2->equalsInt(1)) 804 return C1; // X * 1 == X 805 break; 806 case Instruction::UDiv: 807 case Instruction::SDiv: 808 if (CI2->equalsInt(1)) 809 return C1; // X / 1 == X 810 if (CI2->equalsInt(0)) 811 return UndefValue::get(CI2->getType()); // X / 0 == undef 812 break; 813 case Instruction::URem: 814 case Instruction::SRem: 815 if (CI2->equalsInt(1)) 816 return Constant::getNullValue(CI2->getType()); // X % 1 == 0 817 if (CI2->equalsInt(0)) 818 return UndefValue::get(CI2->getType()); // X % 0 == undef 819 break; 820 case Instruction::And: 821 if (CI2->isZero()) return C2; // X & 0 == 0 822 if (CI2->isAllOnesValue()) 823 return C1; // X & -1 == X 824 825 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 826 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) 827 if (CE1->getOpcode() == Instruction::ZExt) { 828 unsigned DstWidth = CI2->getType()->getBitWidth(); 829 unsigned SrcWidth = 830 CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); 831 APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); 832 if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) 833 return C1; 834 } 835 836 // If and'ing the address of a global with a constant, fold it. 837 if (CE1->getOpcode() == Instruction::PtrToInt && 838 isa<GlobalValue>(CE1->getOperand(0))) { 839 GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0)); 840 841 // Functions are at least 4-byte aligned. 842 unsigned GVAlign = GV->getAlignment(); 843 if (isa<Function>(GV)) 844 GVAlign = std::max(GVAlign, 4U); 845 846 if (GVAlign > 1) { 847 unsigned DstWidth = CI2->getType()->getBitWidth(); 848 unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign)); 849 APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth)); 850 851 // If checking bits we know are clear, return zero. 852 if ((CI2->getValue() & BitsNotSet) == CI2->getValue()) 853 return Constant::getNullValue(CI2->getType()); 854 } 855 } 856 } 857 break; 858 case Instruction::Or: 859 if (CI2->equalsInt(0)) return C1; // X | 0 == X 860 if (CI2->isAllOnesValue()) 861 return C2; // X | -1 == -1 862 break; 863 case Instruction::Xor: 864 if (CI2->equalsInt(0)) return C1; // X ^ 0 == X 865 866 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 867 switch (CE1->getOpcode()) { 868 default: break; 869 case Instruction::ICmp: 870 case Instruction::FCmp: 871 // cmp pred ^ true -> cmp !pred 872 assert(CI2->equalsInt(1)); 873 CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate(); 874 pred = CmpInst::getInversePredicate(pred); 875 return ConstantExpr::getCompare(pred, CE1->getOperand(0), 876 CE1->getOperand(1)); 877 } 878 } 879 break; 880 case Instruction::AShr: 881 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 882 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) 883 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. 884 return ConstantExpr::getLShr(C1, C2); 885 break; 886 } 887 } 888 889 // At this point we know neither constant is an UndefValue. 890 if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { 891 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 892 using namespace APIntOps; 893 const APInt &C1V = CI1->getValue(); 894 const APInt &C2V = CI2->getValue(); 895 switch (Opcode) { 896 default: 897 break; 898 case Instruction::Add: 899 return ConstantInt::get(Context, C1V + C2V); 900 case Instruction::Sub: 901 return ConstantInt::get(Context, C1V - C2V); 902 case Instruction::Mul: 903 return ConstantInt::get(Context, C1V * C2V); 904 case Instruction::UDiv: 905 assert(!CI2->isNullValue() && "Div by zero handled above"); 906 return ConstantInt::get(Context, C1V.udiv(C2V)); 907 case Instruction::SDiv: 908 assert(!CI2->isNullValue() && "Div by zero handled above"); 909 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 910 return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef 911 return ConstantInt::get(Context, C1V.sdiv(C2V)); 912 case Instruction::URem: 913 assert(!CI2->isNullValue() && "Div by zero handled above"); 914 return ConstantInt::get(Context, C1V.urem(C2V)); 915 case Instruction::SRem: 916 assert(!CI2->isNullValue() && "Div by zero handled above"); 917 if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 918 return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef 919 return ConstantInt::get(Context, C1V.srem(C2V)); 920 case Instruction::And: 921 return ConstantInt::get(Context, C1V & C2V); 922 case Instruction::Or: 923 return ConstantInt::get(Context, C1V | C2V); 924 case Instruction::Xor: 925 return ConstantInt::get(Context, C1V ^ C2V); 926 case Instruction::Shl: { 927 uint32_t shiftAmt = C2V.getZExtValue(); 928 if (shiftAmt < C1V.getBitWidth()) 929 return ConstantInt::get(Context, C1V.shl(shiftAmt)); 930 else 931 return UndefValue::get(C1->getType()); // too big shift is undef 932 } 933 case Instruction::LShr: { 934 uint32_t shiftAmt = C2V.getZExtValue(); 935 if (shiftAmt < C1V.getBitWidth()) 936 return ConstantInt::get(Context, C1V.lshr(shiftAmt)); 937 else 938 return UndefValue::get(C1->getType()); // too big shift is undef 939 } 940 case Instruction::AShr: { 941 uint32_t shiftAmt = C2V.getZExtValue(); 942 if (shiftAmt < C1V.getBitWidth()) 943 return ConstantInt::get(Context, C1V.ashr(shiftAmt)); 944 else 945 return UndefValue::get(C1->getType()); // too big shift is undef 946 } 947 } 948 } 949 950 switch (Opcode) { 951 case Instruction::SDiv: 952 case Instruction::UDiv: 953 case Instruction::URem: 954 case Instruction::SRem: 955 case Instruction::LShr: 956 case Instruction::AShr: 957 case Instruction::Shl: 958 if (CI1->equalsInt(0)) return C1; 959 break; 960 default: 961 break; 962 } 963 } else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { 964 if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { 965 APFloat C1V = CFP1->getValueAPF(); 966 APFloat C2V = CFP2->getValueAPF(); 967 APFloat C3V = C1V; // copy for modification 968 switch (Opcode) { 969 default: 970 break; 971 case Instruction::FAdd: 972 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); 973 return ConstantFP::get(Context, C3V); 974 case Instruction::FSub: 975 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); 976 return ConstantFP::get(Context, C3V); 977 case Instruction::FMul: 978 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); 979 return ConstantFP::get(Context, C3V); 980 case Instruction::FDiv: 981 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); 982 return ConstantFP::get(Context, C3V); 983 case Instruction::FRem: 984 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven); 985 return ConstantFP::get(Context, C3V); 986 } 987 } 988 } else if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { 989 ConstantVector *CP1 = dyn_cast<ConstantVector>(C1); 990 ConstantVector *CP2 = dyn_cast<ConstantVector>(C2); 991 if ((CP1 != NULL || isa<ConstantAggregateZero>(C1)) && 992 (CP2 != NULL || isa<ConstantAggregateZero>(C2))) { 993 std::vector<Constant*> Res; 994 const Type* EltTy = VTy->getElementType(); 995 Constant *C1 = 0; 996 Constant *C2 = 0; 997 switch (Opcode) { 998 default: 999 break; 1000 case Instruction::Add: 1001 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1002 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1003 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1004 Res.push_back(ConstantExpr::getAdd(C1, C2)); 1005 } 1006 return ConstantVector::get(Res); 1007 case Instruction::FAdd: 1008 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1009 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1010 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1011 Res.push_back(ConstantExpr::getFAdd(C1, C2)); 1012 } 1013 return ConstantVector::get(Res); 1014 case Instruction::Sub: 1015 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1016 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1017 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1018 Res.push_back(ConstantExpr::getSub(C1, C2)); 1019 } 1020 return ConstantVector::get(Res); 1021 case Instruction::FSub: 1022 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1023 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1024 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1025 Res.push_back(ConstantExpr::getFSub(C1, C2)); 1026 } 1027 return ConstantVector::get(Res); 1028 case Instruction::Mul: 1029 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1030 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1031 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1032 Res.push_back(ConstantExpr::getMul(C1, C2)); 1033 } 1034 return ConstantVector::get(Res); 1035 case Instruction::FMul: 1036 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1037 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1038 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1039 Res.push_back(ConstantExpr::getFMul(C1, C2)); 1040 } 1041 return ConstantVector::get(Res); 1042 case Instruction::UDiv: 1043 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1044 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1045 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1046 Res.push_back(ConstantExpr::getUDiv(C1, C2)); 1047 } 1048 return ConstantVector::get(Res); 1049 case Instruction::SDiv: 1050 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1051 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1052 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1053 Res.push_back(ConstantExpr::getSDiv(C1, C2)); 1054 } 1055 return ConstantVector::get(Res); 1056 case Instruction::FDiv: 1057 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1058 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1059 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1060 Res.push_back(ConstantExpr::getFDiv(C1, C2)); 1061 } 1062 return ConstantVector::get(Res); 1063 case Instruction::URem: 1064 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1065 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1066 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1067 Res.push_back(ConstantExpr::getURem(C1, C2)); 1068 } 1069 return ConstantVector::get(Res); 1070 case Instruction::SRem: 1071 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1072 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1073 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1074 Res.push_back(ConstantExpr::getSRem(C1, C2)); 1075 } 1076 return ConstantVector::get(Res); 1077 case Instruction::FRem: 1078 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1079 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1080 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1081 Res.push_back(ConstantExpr::getFRem(C1, C2)); 1082 } 1083 return ConstantVector::get(Res); 1084 case Instruction::And: 1085 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1086 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1087 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1088 Res.push_back(ConstantExpr::getAnd(C1, C2)); 1089 } 1090 return ConstantVector::get(Res); 1091 case Instruction::Or: 1092 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1093 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1094 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1095 Res.push_back(ConstantExpr::getOr(C1, C2)); 1096 } 1097 return ConstantVector::get(Res); 1098 case Instruction::Xor: 1099 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1100 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1101 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1102 Res.push_back(ConstantExpr::getXor(C1, C2)); 1103 } 1104 return ConstantVector::get(Res); 1105 case Instruction::LShr: 1106 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1107 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1108 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1109 Res.push_back(ConstantExpr::getLShr(C1, C2)); 1110 } 1111 return ConstantVector::get(Res); 1112 case Instruction::AShr: 1113 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1114 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1115 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1116 Res.push_back(ConstantExpr::getAShr(C1, C2)); 1117 } 1118 return ConstantVector::get(Res); 1119 case Instruction::Shl: 1120 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1121 C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); 1122 C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); 1123 Res.push_back(ConstantExpr::getShl(C1, C2)); 1124 } 1125 return ConstantVector::get(Res); 1126 } 1127 } 1128 } 1129 1130 if (isa<ConstantExpr>(C1)) { 1131 // There are many possible foldings we could do here. We should probably 1132 // at least fold add of a pointer with an integer into the appropriate 1133 // getelementptr. This will improve alias analysis a bit. 1134 } else if (isa<ConstantExpr>(C2)) { 1135 // If C2 is a constant expr and C1 isn't, flop them around and fold the 1136 // other way if possible. 1137 switch (Opcode) { 1138 case Instruction::Add: 1139 case Instruction::FAdd: 1140 case Instruction::Mul: 1141 case Instruction::FMul: 1142 case Instruction::And: 1143 case Instruction::Or: 1144 case Instruction::Xor: 1145 // No change of opcode required. 1146 return ConstantFoldBinaryInstruction(Context, Opcode, C2, C1); 1147 1148 case Instruction::Shl: 1149 case Instruction::LShr: 1150 case Instruction::AShr: 1151 case Instruction::Sub: 1152 case Instruction::FSub: 1153 case Instruction::SDiv: 1154 case Instruction::UDiv: 1155 case Instruction::FDiv: 1156 case Instruction::URem: 1157 case Instruction::SRem: 1158 case Instruction::FRem: 1159 default: // These instructions cannot be flopped around. 1160 break; 1161 } 1162 } 1163 1164 // i1 can be simplified in many cases. 1165 if (C1->getType()->isInteger(1)) { 1166 switch (Opcode) { 1167 case Instruction::Add: 1168 case Instruction::Sub: 1169 return ConstantExpr::getXor(C1, C2); 1170 case Instruction::Mul: 1171 return ConstantExpr::getAnd(C1, C2); 1172 case Instruction::Shl: 1173 case Instruction::LShr: 1174 case Instruction::AShr: 1175 // We can assume that C2 == 0. If it were one the result would be 1176 // undefined because the shift value is as large as the bitwidth. 1177 return C1; 1178 case Instruction::SDiv: 1179 case Instruction::UDiv: 1180 // We can assume that C2 == 1. If it were zero the result would be 1181 // undefined through division by zero. 1182 return C1; 1183 case Instruction::URem: 1184 case Instruction::SRem: 1185 // We can assume that C2 == 1. If it were zero the result would be 1186 // undefined through division by zero. 1187 return ConstantInt::getFalse(Context); 1188 default: 1189 break; 1190 } 1191 } 1192 1193 // We don't know how to fold this. 1194 return 0; 1195} 1196 1197/// isZeroSizedType - This type is zero sized if its an array or structure of 1198/// zero sized types. The only leaf zero sized type is an empty structure. 1199static bool isMaybeZeroSizedType(const Type *Ty) { 1200 if (isa<OpaqueType>(Ty)) return true; // Can't say. 1201 if (const StructType *STy = dyn_cast<StructType>(Ty)) { 1202 1203 // If all of elements have zero size, this does too. 1204 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) 1205 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; 1206 return true; 1207 1208 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 1209 return isMaybeZeroSizedType(ATy->getElementType()); 1210 } 1211 return false; 1212} 1213 1214/// IdxCompare - Compare the two constants as though they were getelementptr 1215/// indices. This allows coersion of the types to be the same thing. 1216/// 1217/// If the two constants are the "same" (after coersion), return 0. If the 1218/// first is less than the second, return -1, if the second is less than the 1219/// first, return 1. If the constants are not integral, return -2. 1220/// 1221static int IdxCompare(LLVMContext &Context, Constant *C1, Constant *C2, 1222 const Type *ElTy) { 1223 if (C1 == C2) return 0; 1224 1225 // Ok, we found a different index. If they are not ConstantInt, we can't do 1226 // anything with them. 1227 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) 1228 return -2; // don't know! 1229 1230 // Ok, we have two differing integer indices. Sign extend them to be the same 1231 // type. Long is always big enough, so we use it. 1232 if (!C1->getType()->isInteger(64)) 1233 C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(Context)); 1234 1235 if (!C2->getType()->isInteger(64)) 1236 C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(Context)); 1237 1238 if (C1 == C2) return 0; // They are equal 1239 1240 // If the type being indexed over is really just a zero sized type, there is 1241 // no pointer difference being made here. 1242 if (isMaybeZeroSizedType(ElTy)) 1243 return -2; // dunno. 1244 1245 // If they are really different, now that they are the same type, then we 1246 // found a difference! 1247 if (cast<ConstantInt>(C1)->getSExtValue() < 1248 cast<ConstantInt>(C2)->getSExtValue()) 1249 return -1; 1250 else 1251 return 1; 1252} 1253 1254/// evaluateFCmpRelation - This function determines if there is anything we can 1255/// decide about the two constants provided. This doesn't need to handle simple 1256/// things like ConstantFP comparisons, but should instead handle ConstantExprs. 1257/// If we can determine that the two constants have a particular relation to 1258/// each other, we should return the corresponding FCmpInst predicate, 1259/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in 1260/// ConstantFoldCompareInstruction. 1261/// 1262/// To simplify this code we canonicalize the relation so that the first 1263/// operand is always the most "complex" of the two. We consider ConstantFP 1264/// to be the simplest, and ConstantExprs to be the most complex. 1265static FCmpInst::Predicate evaluateFCmpRelation(LLVMContext &Context, 1266 Constant *V1, Constant *V2) { 1267 assert(V1->getType() == V2->getType() && 1268 "Cannot compare values of different types!"); 1269 1270 // No compile-time operations on this type yet. 1271 if (V1->getType()->isPPC_FP128Ty()) 1272 return FCmpInst::BAD_FCMP_PREDICATE; 1273 1274 // Handle degenerate case quickly 1275 if (V1 == V2) return FCmpInst::FCMP_OEQ; 1276 1277 if (!isa<ConstantExpr>(V1)) { 1278 if (!isa<ConstantExpr>(V2)) { 1279 // We distilled thisUse the standard constant folder for a few cases 1280 ConstantInt *R = 0; 1281 R = dyn_cast<ConstantInt>( 1282 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2)); 1283 if (R && !R->isZero()) 1284 return FCmpInst::FCMP_OEQ; 1285 R = dyn_cast<ConstantInt>( 1286 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2)); 1287 if (R && !R->isZero()) 1288 return FCmpInst::FCMP_OLT; 1289 R = dyn_cast<ConstantInt>( 1290 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2)); 1291 if (R && !R->isZero()) 1292 return FCmpInst::FCMP_OGT; 1293 1294 // Nothing more we can do 1295 return FCmpInst::BAD_FCMP_PREDICATE; 1296 } 1297 1298 // If the first operand is simple and second is ConstantExpr, swap operands. 1299 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(Context, V2, V1); 1300 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) 1301 return FCmpInst::getSwappedPredicate(SwappedRelation); 1302 } else { 1303 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1304 // constantexpr or a simple constant. 1305 ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1306 switch (CE1->getOpcode()) { 1307 case Instruction::FPTrunc: 1308 case Instruction::FPExt: 1309 case Instruction::UIToFP: 1310 case Instruction::SIToFP: 1311 // We might be able to do something with these but we don't right now. 1312 break; 1313 default: 1314 break; 1315 } 1316 } 1317 // There are MANY other foldings that we could perform here. They will 1318 // probably be added on demand, as they seem needed. 1319 return FCmpInst::BAD_FCMP_PREDICATE; 1320} 1321 1322/// evaluateICmpRelation - This function determines if there is anything we can 1323/// decide about the two constants provided. This doesn't need to handle simple 1324/// things like integer comparisons, but should instead handle ConstantExprs 1325/// and GlobalValues. If we can determine that the two constants have a 1326/// particular relation to each other, we should return the corresponding ICmp 1327/// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. 1328/// 1329/// To simplify this code we canonicalize the relation so that the first 1330/// operand is always the most "complex" of the two. We consider simple 1331/// constants (like ConstantInt) to be the simplest, followed by 1332/// GlobalValues, followed by ConstantExpr's (the most complex). 1333/// 1334static ICmpInst::Predicate evaluateICmpRelation(LLVMContext &Context, 1335 Constant *V1, 1336 Constant *V2, 1337 bool isSigned) { 1338 assert(V1->getType() == V2->getType() && 1339 "Cannot compare different types of values!"); 1340 if (V1 == V2) return ICmpInst::ICMP_EQ; 1341 1342 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) { 1343 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) { 1344 // We distilled this down to a simple case, use the standard constant 1345 // folder. 1346 ConstantInt *R = 0; 1347 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; 1348 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1349 if (R && !R->isZero()) 1350 return pred; 1351 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1352 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1353 if (R && !R->isZero()) 1354 return pred; 1355 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1356 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1357 if (R && !R->isZero()) 1358 return pred; 1359 1360 // If we couldn't figure it out, bail. 1361 return ICmpInst::BAD_ICMP_PREDICATE; 1362 } 1363 1364 // If the first operand is simple, swap operands. 1365 ICmpInst::Predicate SwappedRelation = 1366 evaluateICmpRelation(Context, V2, V1, isSigned); 1367 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1368 return ICmpInst::getSwappedPredicate(SwappedRelation); 1369 1370 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) { 1371 if (isa<ConstantExpr>(V2)) { // Swap as necessary. 1372 ICmpInst::Predicate SwappedRelation = 1373 evaluateICmpRelation(Context, V2, V1, isSigned); 1374 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1375 return ICmpInst::getSwappedPredicate(SwappedRelation); 1376 else 1377 return ICmpInst::BAD_ICMP_PREDICATE; 1378 } 1379 1380 // Now we know that the RHS is a GlobalValue or simple constant, 1381 // which (since the types must match) means that it's a ConstantPointerNull. 1382 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) { 1383 // Don't try to decide equality of aliases. 1384 if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2)) 1385 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage()) 1386 return ICmpInst::ICMP_NE; 1387 } else { 1388 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); 1389 // GlobalVals can never be null. Don't try to evaluate aliases. 1390 if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1)) 1391 return ICmpInst::ICMP_NE; 1392 } 1393 } else { 1394 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1395 // constantexpr, a CPR, or a simple constant. 1396 ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1397 Constant *CE1Op0 = CE1->getOperand(0); 1398 1399 switch (CE1->getOpcode()) { 1400 case Instruction::Trunc: 1401 case Instruction::FPTrunc: 1402 case Instruction::FPExt: 1403 case Instruction::FPToUI: 1404 case Instruction::FPToSI: 1405 break; // We can't evaluate floating point casts or truncations. 1406 1407 case Instruction::UIToFP: 1408 case Instruction::SIToFP: 1409 case Instruction::BitCast: 1410 case Instruction::ZExt: 1411 case Instruction::SExt: 1412 // If the cast is not actually changing bits, and the second operand is a 1413 // null pointer, do the comparison with the pre-casted value. 1414 if (V2->isNullValue() && 1415 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) { 1416 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 1417 if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 1418 return evaluateICmpRelation(Context, CE1Op0, 1419 Constant::getNullValue(CE1Op0->getType()), 1420 isSigned); 1421 } 1422 break; 1423 1424 case Instruction::GetElementPtr: 1425 // Ok, since this is a getelementptr, we know that the constant has a 1426 // pointer type. Check the various cases. 1427 if (isa<ConstantPointerNull>(V2)) { 1428 // If we are comparing a GEP to a null pointer, check to see if the base 1429 // of the GEP equals the null pointer. 1430 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1431 if (GV->hasExternalWeakLinkage()) 1432 // Weak linkage GVals could be zero or not. We're comparing that 1433 // to null pointer so its greater-or-equal 1434 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; 1435 else 1436 // If its not weak linkage, the GVal must have a non-zero address 1437 // so the result is greater-than 1438 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1439 } else if (isa<ConstantPointerNull>(CE1Op0)) { 1440 // If we are indexing from a null pointer, check to see if we have any 1441 // non-zero indices. 1442 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) 1443 if (!CE1->getOperand(i)->isNullValue()) 1444 // Offsetting from null, must not be equal. 1445 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1446 // Only zero indexes from null, must still be zero. 1447 return ICmpInst::ICMP_EQ; 1448 } 1449 // Otherwise, we can't really say if the first operand is null or not. 1450 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) { 1451 if (isa<ConstantPointerNull>(CE1Op0)) { 1452 if (CPR2->hasExternalWeakLinkage()) 1453 // Weak linkage GVals could be zero or not. We're comparing it to 1454 // a null pointer, so its less-or-equal 1455 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; 1456 else 1457 // If its not weak linkage, the GVal must have a non-zero address 1458 // so the result is less-than 1459 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1460 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) { 1461 if (CPR1 == CPR2) { 1462 // If this is a getelementptr of the same global, then it must be 1463 // different. Because the types must match, the getelementptr could 1464 // only have at most one index, and because we fold getelementptr's 1465 // with a single zero index, it must be nonzero. 1466 assert(CE1->getNumOperands() == 2 && 1467 !CE1->getOperand(1)->isNullValue() && 1468 "Suprising getelementptr!"); 1469 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1470 } else { 1471 // If they are different globals, we don't know what the value is, 1472 // but they can't be equal. 1473 return ICmpInst::ICMP_NE; 1474 } 1475 } 1476 } else { 1477 ConstantExpr *CE2 = cast<ConstantExpr>(V2); 1478 Constant *CE2Op0 = CE2->getOperand(0); 1479 1480 // There are MANY other foldings that we could perform here. They will 1481 // probably be added on demand, as they seem needed. 1482 switch (CE2->getOpcode()) { 1483 default: break; 1484 case Instruction::GetElementPtr: 1485 // By far the most common case to handle is when the base pointers are 1486 // obviously to the same or different globals. 1487 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { 1488 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal 1489 return ICmpInst::ICMP_NE; 1490 // Ok, we know that both getelementptr instructions are based on the 1491 // same global. From this, we can precisely determine the relative 1492 // ordering of the resultant pointers. 1493 unsigned i = 1; 1494 1495 // The logic below assumes that the result of the comparison 1496 // can be determined by finding the first index that differs. 1497 // This doesn't work if there is over-indexing in any 1498 // subsequent indices, so check for that case first. 1499 if (!CE1->isGEPWithNoNotionalOverIndexing() || 1500 !CE2->isGEPWithNoNotionalOverIndexing()) 1501 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1502 1503 // Compare all of the operands the GEP's have in common. 1504 gep_type_iterator GTI = gep_type_begin(CE1); 1505 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); 1506 ++i, ++GTI) 1507 switch (IdxCompare(Context, CE1->getOperand(i), 1508 CE2->getOperand(i), GTI.getIndexedType())) { 1509 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; 1510 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; 1511 case -2: return ICmpInst::BAD_ICMP_PREDICATE; 1512 } 1513 1514 // Ok, we ran out of things they have in common. If any leftovers 1515 // are non-zero then we have a difference, otherwise we are equal. 1516 for (; i < CE1->getNumOperands(); ++i) 1517 if (!CE1->getOperand(i)->isNullValue()) { 1518 if (isa<ConstantInt>(CE1->getOperand(i))) 1519 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1520 else 1521 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1522 } 1523 1524 for (; i < CE2->getNumOperands(); ++i) 1525 if (!CE2->getOperand(i)->isNullValue()) { 1526 if (isa<ConstantInt>(CE2->getOperand(i))) 1527 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1528 else 1529 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1530 } 1531 return ICmpInst::ICMP_EQ; 1532 } 1533 } 1534 } 1535 default: 1536 break; 1537 } 1538 } 1539 1540 return ICmpInst::BAD_ICMP_PREDICATE; 1541} 1542 1543Constant *llvm::ConstantFoldCompareInstruction(LLVMContext &Context, 1544 unsigned short pred, 1545 Constant *C1, Constant *C2) { 1546 const Type *ResultTy; 1547 if (const VectorType *VT = dyn_cast<VectorType>(C1->getType())) 1548 ResultTy = VectorType::get(Type::getInt1Ty(Context), VT->getNumElements()); 1549 else 1550 ResultTy = Type::getInt1Ty(Context); 1551 1552 // Fold FCMP_FALSE/FCMP_TRUE unconditionally. 1553 if (pred == FCmpInst::FCMP_FALSE) 1554 return Constant::getNullValue(ResultTy); 1555 1556 if (pred == FCmpInst::FCMP_TRUE) 1557 return Constant::getAllOnesValue(ResultTy); 1558 1559 // Handle some degenerate cases first 1560 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) 1561 return UndefValue::get(ResultTy); 1562 1563 // No compile-time operations on this type yet. 1564 if (C1->getType()->isPPC_FP128Ty()) 1565 return 0; 1566 1567 // icmp eq/ne(null,GV) -> false/true 1568 if (C1->isNullValue()) { 1569 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) 1570 // Don't try to evaluate aliases. External weak GV can be null. 1571 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1572 if (pred == ICmpInst::ICMP_EQ) 1573 return ConstantInt::getFalse(Context); 1574 else if (pred == ICmpInst::ICMP_NE) 1575 return ConstantInt::getTrue(Context); 1576 } 1577 // icmp eq/ne(GV,null) -> false/true 1578 } else if (C2->isNullValue()) { 1579 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) 1580 // Don't try to evaluate aliases. External weak GV can be null. 1581 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1582 if (pred == ICmpInst::ICMP_EQ) 1583 return ConstantInt::getFalse(Context); 1584 else if (pred == ICmpInst::ICMP_NE) 1585 return ConstantInt::getTrue(Context); 1586 } 1587 } 1588 1589 // If the comparison is a comparison between two i1's, simplify it. 1590 if (C1->getType()->isInteger(1)) { 1591 switch(pred) { 1592 case ICmpInst::ICMP_EQ: 1593 if (isa<ConstantInt>(C2)) 1594 return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2)); 1595 return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2); 1596 case ICmpInst::ICMP_NE: 1597 return ConstantExpr::getXor(C1, C2); 1598 default: 1599 break; 1600 } 1601 } 1602 1603 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { 1604 APInt V1 = cast<ConstantInt>(C1)->getValue(); 1605 APInt V2 = cast<ConstantInt>(C2)->getValue(); 1606 switch (pred) { 1607 default: llvm_unreachable("Invalid ICmp Predicate"); return 0; 1608 case ICmpInst::ICMP_EQ: 1609 return ConstantInt::get(Type::getInt1Ty(Context), V1 == V2); 1610 case ICmpInst::ICMP_NE: 1611 return ConstantInt::get(Type::getInt1Ty(Context), V1 != V2); 1612 case ICmpInst::ICMP_SLT: 1613 return ConstantInt::get(Type::getInt1Ty(Context), V1.slt(V2)); 1614 case ICmpInst::ICMP_SGT: 1615 return ConstantInt::get(Type::getInt1Ty(Context), V1.sgt(V2)); 1616 case ICmpInst::ICMP_SLE: 1617 return ConstantInt::get(Type::getInt1Ty(Context), V1.sle(V2)); 1618 case ICmpInst::ICMP_SGE: 1619 return ConstantInt::get(Type::getInt1Ty(Context), V1.sge(V2)); 1620 case ICmpInst::ICMP_ULT: 1621 return ConstantInt::get(Type::getInt1Ty(Context), V1.ult(V2)); 1622 case ICmpInst::ICMP_UGT: 1623 return ConstantInt::get(Type::getInt1Ty(Context), V1.ugt(V2)); 1624 case ICmpInst::ICMP_ULE: 1625 return ConstantInt::get(Type::getInt1Ty(Context), V1.ule(V2)); 1626 case ICmpInst::ICMP_UGE: 1627 return ConstantInt::get(Type::getInt1Ty(Context), V1.uge(V2)); 1628 } 1629 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { 1630 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); 1631 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); 1632 APFloat::cmpResult R = C1V.compare(C2V); 1633 switch (pred) { 1634 default: llvm_unreachable("Invalid FCmp Predicate"); return 0; 1635 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse(Context); 1636 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue(Context); 1637 case FCmpInst::FCMP_UNO: 1638 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpUnordered); 1639 case FCmpInst::FCMP_ORD: 1640 return ConstantInt::get(Type::getInt1Ty(Context), R!=APFloat::cmpUnordered); 1641 case FCmpInst::FCMP_UEQ: 1642 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpUnordered || 1643 R==APFloat::cmpEqual); 1644 case FCmpInst::FCMP_OEQ: 1645 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpEqual); 1646 case FCmpInst::FCMP_UNE: 1647 return ConstantInt::get(Type::getInt1Ty(Context), R!=APFloat::cmpEqual); 1648 case FCmpInst::FCMP_ONE: 1649 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpLessThan || 1650 R==APFloat::cmpGreaterThan); 1651 case FCmpInst::FCMP_ULT: 1652 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpUnordered || 1653 R==APFloat::cmpLessThan); 1654 case FCmpInst::FCMP_OLT: 1655 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpLessThan); 1656 case FCmpInst::FCMP_UGT: 1657 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpUnordered || 1658 R==APFloat::cmpGreaterThan); 1659 case FCmpInst::FCMP_OGT: 1660 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpGreaterThan); 1661 case FCmpInst::FCMP_ULE: 1662 return ConstantInt::get(Type::getInt1Ty(Context), R!=APFloat::cmpGreaterThan); 1663 case FCmpInst::FCMP_OLE: 1664 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpLessThan || 1665 R==APFloat::cmpEqual); 1666 case FCmpInst::FCMP_UGE: 1667 return ConstantInt::get(Type::getInt1Ty(Context), R!=APFloat::cmpLessThan); 1668 case FCmpInst::FCMP_OGE: 1669 return ConstantInt::get(Type::getInt1Ty(Context), R==APFloat::cmpGreaterThan || 1670 R==APFloat::cmpEqual); 1671 } 1672 } else if (isa<VectorType>(C1->getType())) { 1673 SmallVector<Constant*, 16> C1Elts, C2Elts; 1674 C1->getVectorElements(Context, C1Elts); 1675 C2->getVectorElements(Context, C2Elts); 1676 1677 // If we can constant fold the comparison of each element, constant fold 1678 // the whole vector comparison. 1679 SmallVector<Constant*, 4> ResElts; 1680 for (unsigned i = 0, e = C1Elts.size(); i != e; ++i) { 1681 // Compare the elements, producing an i1 result or constant expr. 1682 ResElts.push_back( 1683 ConstantExpr::getCompare(pred, C1Elts[i], C2Elts[i])); 1684 } 1685 return ConstantVector::get(&ResElts[0], ResElts.size()); 1686 } 1687 1688 if (C1->getType()->isFloatingPoint()) { 1689 int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1690 switch (evaluateFCmpRelation(Context, C1, C2)) { 1691 default: llvm_unreachable("Unknown relation!"); 1692 case FCmpInst::FCMP_UNO: 1693 case FCmpInst::FCMP_ORD: 1694 case FCmpInst::FCMP_UEQ: 1695 case FCmpInst::FCMP_UNE: 1696 case FCmpInst::FCMP_ULT: 1697 case FCmpInst::FCMP_UGT: 1698 case FCmpInst::FCMP_ULE: 1699 case FCmpInst::FCMP_UGE: 1700 case FCmpInst::FCMP_TRUE: 1701 case FCmpInst::FCMP_FALSE: 1702 case FCmpInst::BAD_FCMP_PREDICATE: 1703 break; // Couldn't determine anything about these constants. 1704 case FCmpInst::FCMP_OEQ: // We know that C1 == C2 1705 Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || 1706 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || 1707 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1708 break; 1709 case FCmpInst::FCMP_OLT: // We know that C1 < C2 1710 Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1711 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || 1712 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); 1713 break; 1714 case FCmpInst::FCMP_OGT: // We know that C1 > C2 1715 Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1716 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || 1717 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1718 break; 1719 case FCmpInst::FCMP_OLE: // We know that C1 <= C2 1720 // We can only partially decide this relation. 1721 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1722 Result = 0; 1723 else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1724 Result = 1; 1725 break; 1726 case FCmpInst::FCMP_OGE: // We known that C1 >= C2 1727 // We can only partially decide this relation. 1728 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1729 Result = 0; 1730 else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1731 Result = 1; 1732 break; 1733 case ICmpInst::ICMP_NE: // We know that C1 != C2 1734 // We can only partially decide this relation. 1735 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) 1736 Result = 0; 1737 else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) 1738 Result = 1; 1739 break; 1740 } 1741 1742 // If we evaluated the result, return it now. 1743 if (Result != -1) 1744 return ConstantInt::get(Type::getInt1Ty(Context), Result); 1745 1746 } else { 1747 // Evaluate the relation between the two constants, per the predicate. 1748 int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1749 switch (evaluateICmpRelation(Context, C1, C2, CmpInst::isSigned(pred))) { 1750 default: llvm_unreachable("Unknown relational!"); 1751 case ICmpInst::BAD_ICMP_PREDICATE: 1752 break; // Couldn't determine anything about these constants. 1753 case ICmpInst::ICMP_EQ: // We know the constants are equal! 1754 // If we know the constants are equal, we can decide the result of this 1755 // computation precisely. 1756 Result = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred); 1757 break; 1758 case ICmpInst::ICMP_ULT: 1759 switch (pred) { 1760 case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE: 1761 Result = 1; break; 1762 case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE: 1763 Result = 0; break; 1764 } 1765 break; 1766 case ICmpInst::ICMP_SLT: 1767 switch (pred) { 1768 case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE: 1769 Result = 1; break; 1770 case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE: 1771 Result = 0; break; 1772 } 1773 break; 1774 case ICmpInst::ICMP_UGT: 1775 switch (pred) { 1776 case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE: 1777 Result = 1; break; 1778 case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE: 1779 Result = 0; break; 1780 } 1781 break; 1782 case ICmpInst::ICMP_SGT: 1783 switch (pred) { 1784 case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE: 1785 Result = 1; break; 1786 case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE: 1787 Result = 0; break; 1788 } 1789 break; 1790 case ICmpInst::ICMP_ULE: 1791 if (pred == ICmpInst::ICMP_UGT) Result = 0; 1792 if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1; 1793 break; 1794 case ICmpInst::ICMP_SLE: 1795 if (pred == ICmpInst::ICMP_SGT) Result = 0; 1796 if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1; 1797 break; 1798 case ICmpInst::ICMP_UGE: 1799 if (pred == ICmpInst::ICMP_ULT) Result = 0; 1800 if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1; 1801 break; 1802 case ICmpInst::ICMP_SGE: 1803 if (pred == ICmpInst::ICMP_SLT) Result = 0; 1804 if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1; 1805 break; 1806 case ICmpInst::ICMP_NE: 1807 if (pred == ICmpInst::ICMP_EQ) Result = 0; 1808 if (pred == ICmpInst::ICMP_NE) Result = 1; 1809 break; 1810 } 1811 1812 // If we evaluated the result, return it now. 1813 if (Result != -1) 1814 return ConstantInt::get(Type::getInt1Ty(Context), Result); 1815 1816 // If the right hand side is a bitcast, try using its inverse to simplify 1817 // it by moving it to the left hand side. 1818 if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) { 1819 if (CE2->getOpcode() == Instruction::BitCast) { 1820 Constant *CE2Op0 = CE2->getOperand(0); 1821 Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType()); 1822 return ConstantExpr::getICmp(pred, Inverse, CE2Op0); 1823 } 1824 } 1825 1826 // If the left hand side is an extension, try eliminating it. 1827 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1828 if (CE1->getOpcode() == Instruction::SExt || 1829 CE1->getOpcode() == Instruction::ZExt) { 1830 Constant *CE1Op0 = CE1->getOperand(0); 1831 Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType()); 1832 if (CE1Inverse == CE1Op0) { 1833 // Check whether we can safely truncate the right hand side. 1834 Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType()); 1835 if (ConstantExpr::getZExt(C2Inverse, C2->getType()) == C2) { 1836 return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse); 1837 } 1838 } 1839 } 1840 } 1841 1842 if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) || 1843 (C1->isNullValue() && !C2->isNullValue())) { 1844 // If C2 is a constant expr and C1 isn't, flip them around and fold the 1845 // other way if possible. 1846 // Also, if C1 is null and C2 isn't, flip them around. 1847 switch (pred) { 1848 case ICmpInst::ICMP_EQ: 1849 case ICmpInst::ICMP_NE: 1850 // No change of predicate required. 1851 return ConstantExpr::getICmp(pred, C2, C1); 1852 1853 case ICmpInst::ICMP_ULT: 1854 case ICmpInst::ICMP_SLT: 1855 case ICmpInst::ICMP_UGT: 1856 case ICmpInst::ICMP_SGT: 1857 case ICmpInst::ICMP_ULE: 1858 case ICmpInst::ICMP_SLE: 1859 case ICmpInst::ICMP_UGE: 1860 case ICmpInst::ICMP_SGE: 1861 // Change the predicate as necessary to swap the operands. 1862 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); 1863 return ConstantExpr::getICmp(pred, C2, C1); 1864 1865 default: // These predicates cannot be flopped around. 1866 break; 1867 } 1868 } 1869 } 1870 return 0; 1871} 1872 1873/// isInBoundsIndices - Test whether the given sequence of *normalized* indices 1874/// is "inbounds". 1875static bool isInBoundsIndices(Constant *const *Idxs, size_t NumIdx) { 1876 // No indices means nothing that could be out of bounds. 1877 if (NumIdx == 0) return true; 1878 1879 // If the first index is zero, it's in bounds. 1880 if (Idxs[0]->isNullValue()) return true; 1881 1882 // If the first index is one and all the rest are zero, it's in bounds, 1883 // by the one-past-the-end rule. 1884 if (!cast<ConstantInt>(Idxs[0])->isOne()) 1885 return false; 1886 for (unsigned i = 1, e = NumIdx; i != e; ++i) 1887 if (!Idxs[i]->isNullValue()) 1888 return false; 1889 return true; 1890} 1891 1892Constant *llvm::ConstantFoldGetElementPtr(LLVMContext &Context, 1893 Constant *C, 1894 bool inBounds, 1895 Constant* const *Idxs, 1896 unsigned NumIdx) { 1897 if (NumIdx == 0 || 1898 (NumIdx == 1 && Idxs[0]->isNullValue())) 1899 return C; 1900 1901 if (isa<UndefValue>(C)) { 1902 const PointerType *Ptr = cast<PointerType>(C->getType()); 1903 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr, 1904 (Value **)Idxs, 1905 (Value **)Idxs+NumIdx); 1906 assert(Ty != 0 && "Invalid indices for GEP!"); 1907 return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); 1908 } 1909 1910 Constant *Idx0 = Idxs[0]; 1911 if (C->isNullValue()) { 1912 bool isNull = true; 1913 for (unsigned i = 0, e = NumIdx; i != e; ++i) 1914 if (!Idxs[i]->isNullValue()) { 1915 isNull = false; 1916 break; 1917 } 1918 if (isNull) { 1919 const PointerType *Ptr = cast<PointerType>(C->getType()); 1920 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr, 1921 (Value**)Idxs, 1922 (Value**)Idxs+NumIdx); 1923 assert(Ty != 0 && "Invalid indices for GEP!"); 1924 return ConstantPointerNull::get( 1925 PointerType::get(Ty,Ptr->getAddressSpace())); 1926 } 1927 } 1928 1929 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { 1930 // Combine Indices - If the source pointer to this getelementptr instruction 1931 // is a getelementptr instruction, combine the indices of the two 1932 // getelementptr instructions into a single instruction. 1933 // 1934 if (CE->getOpcode() == Instruction::GetElementPtr) { 1935 const Type *LastTy = 0; 1936 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); 1937 I != E; ++I) 1938 LastTy = *I; 1939 1940 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) { 1941 SmallVector<Value*, 16> NewIndices; 1942 NewIndices.reserve(NumIdx + CE->getNumOperands()); 1943 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) 1944 NewIndices.push_back(CE->getOperand(i)); 1945 1946 // Add the last index of the source with the first index of the new GEP. 1947 // Make sure to handle the case when they are actually different types. 1948 Constant *Combined = CE->getOperand(CE->getNumOperands()-1); 1949 // Otherwise it must be an array. 1950 if (!Idx0->isNullValue()) { 1951 const Type *IdxTy = Combined->getType(); 1952 if (IdxTy != Idx0->getType()) { 1953 Constant *C1 = 1954 ConstantExpr::getSExtOrBitCast(Idx0, Type::getInt64Ty(Context)); 1955 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, 1956 Type::getInt64Ty(Context)); 1957 Combined = ConstantExpr::get(Instruction::Add, C1, C2); 1958 } else { 1959 Combined = 1960 ConstantExpr::get(Instruction::Add, Idx0, Combined); 1961 } 1962 } 1963 1964 NewIndices.push_back(Combined); 1965 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx); 1966 return (inBounds && cast<GEPOperator>(CE)->isInBounds()) ? 1967 ConstantExpr::getInBoundsGetElementPtr(CE->getOperand(0), 1968 &NewIndices[0], 1969 NewIndices.size()) : 1970 ConstantExpr::getGetElementPtr(CE->getOperand(0), 1971 &NewIndices[0], 1972 NewIndices.size()); 1973 } 1974 } 1975 1976 // Implement folding of: 1977 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*), 1978 // long 0, long 0) 1979 // To: int* getelementptr ([3 x int]* %X, long 0, long 0) 1980 // 1981 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) { 1982 if (const PointerType *SPT = 1983 dyn_cast<PointerType>(CE->getOperand(0)->getType())) 1984 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType())) 1985 if (const ArrayType *CAT = 1986 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType())) 1987 if (CAT->getElementType() == SAT->getElementType()) 1988 return inBounds ? 1989 ConstantExpr::getInBoundsGetElementPtr( 1990 (Constant*)CE->getOperand(0), Idxs, NumIdx) : 1991 ConstantExpr::getGetElementPtr( 1992 (Constant*)CE->getOperand(0), Idxs, NumIdx); 1993 } 1994 1995 // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1) 1996 // Into: inttoptr (i64 0 to i8*) 1997 // This happens with pointers to member functions in C++. 1998 if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 && 1999 isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) && 2000 cast<PointerType>(CE->getType())->getElementType() == 2001 Type::getInt8Ty(Context)) { 2002 Constant *Base = CE->getOperand(0); 2003 Constant *Offset = Idxs[0]; 2004 2005 // Convert the smaller integer to the larger type. 2006 if (Offset->getType()->getPrimitiveSizeInBits() < 2007 Base->getType()->getPrimitiveSizeInBits()) 2008 Offset = ConstantExpr::getSExt(Offset, Base->getType()); 2009 else if (Base->getType()->getPrimitiveSizeInBits() < 2010 Offset->getType()->getPrimitiveSizeInBits()) 2011 Base = ConstantExpr::getZExt(Base, Offset->getType()); 2012 2013 Base = ConstantExpr::getAdd(Base, Offset); 2014 return ConstantExpr::getIntToPtr(Base, CE->getType()); 2015 } 2016 } 2017 2018 // Check to see if any array indices are not within the corresponding 2019 // notional array bounds. If so, try to determine if they can be factored 2020 // out into preceding dimensions. 2021 bool Unknown = false; 2022 SmallVector<Constant *, 8> NewIdxs; 2023 const Type *Ty = C->getType(); 2024 const Type *Prev = 0; 2025 for (unsigned i = 0; i != NumIdx; 2026 Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) { 2027 if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) { 2028 if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) 2029 if (ATy->getNumElements() <= INT64_MAX && 2030 ATy->getNumElements() != 0 && 2031 CI->getSExtValue() >= (int64_t)ATy->getNumElements()) { 2032 if (isa<SequentialType>(Prev)) { 2033 // It's out of range, but we can factor it into the prior 2034 // dimension. 2035 NewIdxs.resize(NumIdx); 2036 ConstantInt *Factor = ConstantInt::get(CI->getType(), 2037 ATy->getNumElements()); 2038 NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); 2039 2040 Constant *PrevIdx = Idxs[i-1]; 2041 Constant *Div = ConstantExpr::getSDiv(CI, Factor); 2042 2043 // Before adding, extend both operands to i64 to avoid 2044 // overflow trouble. 2045 if (!PrevIdx->getType()->isInteger(64)) 2046 PrevIdx = ConstantExpr::getSExt(PrevIdx, 2047 Type::getInt64Ty(Context)); 2048 if (!Div->getType()->isInteger(64)) 2049 Div = ConstantExpr::getSExt(Div, 2050 Type::getInt64Ty(Context)); 2051 2052 NewIdxs[i-1] = ConstantExpr::getAdd(PrevIdx, Div); 2053 } else { 2054 // It's out of range, but the prior dimension is a struct 2055 // so we can't do anything about it. 2056 Unknown = true; 2057 } 2058 } 2059 } else { 2060 // We don't know if it's in range or not. 2061 Unknown = true; 2062 } 2063 } 2064 2065 // If we did any factoring, start over with the adjusted indices. 2066 if (!NewIdxs.empty()) { 2067 for (unsigned i = 0; i != NumIdx; ++i) 2068 if (!NewIdxs[i]) NewIdxs[i] = Idxs[i]; 2069 return inBounds ? 2070 ConstantExpr::getInBoundsGetElementPtr(C, NewIdxs.data(), 2071 NewIdxs.size()) : 2072 ConstantExpr::getGetElementPtr(C, NewIdxs.data(), NewIdxs.size()); 2073 } 2074 2075 // If all indices are known integers and normalized, we can do a simple 2076 // check for the "inbounds" property. 2077 if (!Unknown && !inBounds && 2078 isa<GlobalVariable>(C) && isInBoundsIndices(Idxs, NumIdx)) 2079 return ConstantExpr::getInBoundsGetElementPtr(C, Idxs, NumIdx); 2080 2081 return 0; 2082} 2083