1249259Sdim//===- ConstantFold.cpp - LLVM constant folder ----------------------------===// 2249259Sdim// 3249259Sdim// The LLVM Compiler Infrastructure 4249259Sdim// 5249259Sdim// This file is distributed under the University of Illinois Open Source 6249259Sdim// License. See LICENSE.TXT for details. 7249259Sdim// 8249259Sdim//===----------------------------------------------------------------------===// 9249259Sdim// 10249259Sdim// This file implements folding of constants for LLVM. This implements the 11249259Sdim// (internal) ConstantFold.h interface, which is used by the 12249259Sdim// ConstantExpr::get* methods to automatically fold constants when possible. 13249259Sdim// 14249259Sdim// The current constant folding implementation is implemented in two pieces: the 15249259Sdim// pieces that don't need DataLayout, and the pieces that do. This is to avoid 16249259Sdim// a dependence in IR on Target. 17249259Sdim// 18249259Sdim//===----------------------------------------------------------------------===// 19249259Sdim 20249259Sdim#include "ConstantFold.h" 21249259Sdim#include "llvm/ADT/SmallVector.h" 22249259Sdim#include "llvm/IR/Constants.h" 23249259Sdim#include "llvm/IR/DerivedTypes.h" 24249259Sdim#include "llvm/IR/Function.h" 25249259Sdim#include "llvm/IR/GlobalAlias.h" 26249259Sdim#include "llvm/IR/GlobalVariable.h" 27249259Sdim#include "llvm/IR/Instructions.h" 28249259Sdim#include "llvm/IR/Operator.h" 29249259Sdim#include "llvm/Support/Compiler.h" 30249259Sdim#include "llvm/Support/ErrorHandling.h" 31249259Sdim#include "llvm/Support/GetElementPtrTypeIterator.h" 32249259Sdim#include "llvm/Support/ManagedStatic.h" 33249259Sdim#include "llvm/Support/MathExtras.h" 34249259Sdim#include <limits> 35249259Sdimusing namespace llvm; 36249259Sdim 37249259Sdim//===----------------------------------------------------------------------===// 38249259Sdim// ConstantFold*Instruction Implementations 39249259Sdim//===----------------------------------------------------------------------===// 40249259Sdim 41249259Sdim/// BitCastConstantVector - Convert the specified vector Constant node to the 42249259Sdim/// specified vector type. At this point, we know that the elements of the 43249259Sdim/// input vector constant are all simple integer or FP values. 44249259Sdimstatic Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) { 45249259Sdim 46249259Sdim if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy); 47249259Sdim if (CV->isNullValue()) return Constant::getNullValue(DstTy); 48249259Sdim 49249259Sdim // If this cast changes element count then we can't handle it here: 50249259Sdim // doing so requires endianness information. This should be handled by 51249259Sdim // Analysis/ConstantFolding.cpp 52249259Sdim unsigned NumElts = DstTy->getNumElements(); 53249259Sdim if (NumElts != CV->getType()->getVectorNumElements()) 54249259Sdim return 0; 55249259Sdim 56249259Sdim Type *DstEltTy = DstTy->getElementType(); 57249259Sdim 58249259Sdim SmallVector<Constant*, 16> Result; 59249259Sdim Type *Ty = IntegerType::get(CV->getContext(), 32); 60249259Sdim for (unsigned i = 0; i != NumElts; ++i) { 61249259Sdim Constant *C = 62249259Sdim ConstantExpr::getExtractElement(CV, ConstantInt::get(Ty, i)); 63249259Sdim C = ConstantExpr::getBitCast(C, DstEltTy); 64249259Sdim Result.push_back(C); 65249259Sdim } 66249259Sdim 67249259Sdim return ConstantVector::get(Result); 68249259Sdim} 69249259Sdim 70249259Sdim/// This function determines which opcode to use to fold two constant cast 71249259Sdim/// expressions together. It uses CastInst::isEliminableCastPair to determine 72249259Sdim/// the opcode. Consequently its just a wrapper around that function. 73249259Sdim/// @brief Determine if it is valid to fold a cast of a cast 74249259Sdimstatic unsigned 75249259SdimfoldConstantCastPair( 76249259Sdim unsigned opc, ///< opcode of the second cast constant expression 77249259Sdim ConstantExpr *Op, ///< the first cast constant expression 78263508Sdim Type *DstTy ///< destination type of the first cast 79249259Sdim) { 80249259Sdim assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!"); 81249259Sdim assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type"); 82249259Sdim assert(CastInst::isCast(opc) && "Invalid cast opcode"); 83249259Sdim 84249259Sdim // The the types and opcodes for the two Cast constant expressions 85249259Sdim Type *SrcTy = Op->getOperand(0)->getType(); 86249259Sdim Type *MidTy = Op->getType(); 87249259Sdim Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode()); 88249259Sdim Instruction::CastOps secondOp = Instruction::CastOps(opc); 89249259Sdim 90263508Sdim // Assume that pointers are never more than 64 bits wide, and only use this 91263508Sdim // for the middle type. Otherwise we could end up folding away illegal 92263508Sdim // bitcasts between address spaces with different sizes. 93249259Sdim IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext()); 94249259Sdim 95249259Sdim // Let CastInst::isEliminableCastPair do the heavy lifting. 96249259Sdim return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy, 97263508Sdim 0, FakeIntPtrTy, 0); 98249259Sdim} 99249259Sdim 100249259Sdimstatic Constant *FoldBitCast(Constant *V, Type *DestTy) { 101249259Sdim Type *SrcTy = V->getType(); 102249259Sdim if (SrcTy == DestTy) 103249259Sdim return V; // no-op cast 104249259Sdim 105249259Sdim // Check to see if we are casting a pointer to an aggregate to a pointer to 106249259Sdim // the first element. If so, return the appropriate GEP instruction. 107249259Sdim if (PointerType *PTy = dyn_cast<PointerType>(V->getType())) 108249259Sdim if (PointerType *DPTy = dyn_cast<PointerType>(DestTy)) 109249259Sdim if (PTy->getAddressSpace() == DPTy->getAddressSpace() 110249259Sdim && DPTy->getElementType()->isSized()) { 111249259Sdim SmallVector<Value*, 8> IdxList; 112249259Sdim Value *Zero = 113249259Sdim Constant::getNullValue(Type::getInt32Ty(DPTy->getContext())); 114249259Sdim IdxList.push_back(Zero); 115249259Sdim Type *ElTy = PTy->getElementType(); 116249259Sdim while (ElTy != DPTy->getElementType()) { 117249259Sdim if (StructType *STy = dyn_cast<StructType>(ElTy)) { 118249259Sdim if (STy->getNumElements() == 0) break; 119249259Sdim ElTy = STy->getElementType(0); 120249259Sdim IdxList.push_back(Zero); 121249259Sdim } else if (SequentialType *STy = 122249259Sdim dyn_cast<SequentialType>(ElTy)) { 123249259Sdim if (ElTy->isPointerTy()) break; // Can't index into pointers! 124249259Sdim ElTy = STy->getElementType(); 125249259Sdim IdxList.push_back(Zero); 126249259Sdim } else { 127249259Sdim break; 128249259Sdim } 129249259Sdim } 130249259Sdim 131249259Sdim if (ElTy == DPTy->getElementType()) 132249259Sdim // This GEP is inbounds because all indices are zero. 133249259Sdim return ConstantExpr::getInBoundsGetElementPtr(V, IdxList); 134249259Sdim } 135249259Sdim 136249259Sdim // Handle casts from one vector constant to another. We know that the src 137249259Sdim // and dest type have the same size (otherwise its an illegal cast). 138249259Sdim if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { 139249259Sdim if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { 140249259Sdim assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && 141249259Sdim "Not cast between same sized vectors!"); 142249259Sdim SrcTy = NULL; 143249259Sdim // First, check for null. Undef is already handled. 144249259Sdim if (isa<ConstantAggregateZero>(V)) 145249259Sdim return Constant::getNullValue(DestTy); 146249259Sdim 147249259Sdim // Handle ConstantVector and ConstantAggregateVector. 148249259Sdim return BitCastConstantVector(V, DestPTy); 149249259Sdim } 150249259Sdim 151249259Sdim // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts 152249259Sdim // This allows for other simplifications (although some of them 153249259Sdim // can only be handled by Analysis/ConstantFolding.cpp). 154249259Sdim if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) 155249259Sdim return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy); 156249259Sdim } 157249259Sdim 158249259Sdim // Finally, implement bitcast folding now. The code below doesn't handle 159249259Sdim // bitcast right. 160249259Sdim if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. 161249259Sdim return ConstantPointerNull::get(cast<PointerType>(DestTy)); 162249259Sdim 163249259Sdim // Handle integral constant input. 164249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 165249259Sdim if (DestTy->isIntegerTy()) 166249259Sdim // Integral -> Integral. This is a no-op because the bit widths must 167249259Sdim // be the same. Consequently, we just fold to V. 168249259Sdim return V; 169249259Sdim 170249259Sdim if (DestTy->isFloatingPointTy()) 171249259Sdim return ConstantFP::get(DestTy->getContext(), 172249259Sdim APFloat(DestTy->getFltSemantics(), 173249259Sdim CI->getValue())); 174249259Sdim 175249259Sdim // Otherwise, can't fold this (vector?) 176249259Sdim return 0; 177249259Sdim } 178249259Sdim 179249259Sdim // Handle ConstantFP input: FP -> Integral. 180249259Sdim if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) 181249259Sdim return ConstantInt::get(FP->getContext(), 182249259Sdim FP->getValueAPF().bitcastToAPInt()); 183249259Sdim 184249259Sdim return 0; 185249259Sdim} 186249259Sdim 187249259Sdim 188249259Sdim/// ExtractConstantBytes - V is an integer constant which only has a subset of 189249259Sdim/// its bytes used. The bytes used are indicated by ByteStart (which is the 190249259Sdim/// first byte used, counting from the least significant byte) and ByteSize, 191249259Sdim/// which is the number of bytes used. 192249259Sdim/// 193249259Sdim/// This function analyzes the specified constant to see if the specified byte 194249259Sdim/// range can be returned as a simplified constant. If so, the constant is 195249259Sdim/// returned, otherwise null is returned. 196249259Sdim/// 197249259Sdimstatic Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, 198249259Sdim unsigned ByteSize) { 199249259Sdim assert(C->getType()->isIntegerTy() && 200249259Sdim (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 && 201249259Sdim "Non-byte sized integer input"); 202249259Sdim unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; 203249259Sdim assert(ByteSize && "Must be accessing some piece"); 204249259Sdim assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input"); 205249259Sdim assert(ByteSize != CSize && "Should not extract everything"); 206249259Sdim 207249259Sdim // Constant Integers are simple. 208249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { 209249259Sdim APInt V = CI->getValue(); 210249259Sdim if (ByteStart) 211249259Sdim V = V.lshr(ByteStart*8); 212249259Sdim V = V.trunc(ByteSize*8); 213249259Sdim return ConstantInt::get(CI->getContext(), V); 214249259Sdim } 215249259Sdim 216249259Sdim // In the input is a constant expr, we might be able to recursively simplify. 217249259Sdim // If not, we definitely can't do anything. 218249259Sdim ConstantExpr *CE = dyn_cast<ConstantExpr>(C); 219249259Sdim if (CE == 0) return 0; 220249259Sdim 221249259Sdim switch (CE->getOpcode()) { 222249259Sdim default: return 0; 223249259Sdim case Instruction::Or: { 224249259Sdim Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 225249259Sdim if (RHS == 0) 226249259Sdim return 0; 227249259Sdim 228249259Sdim // X | -1 -> -1. 229249259Sdim if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) 230249259Sdim if (RHSC->isAllOnesValue()) 231249259Sdim return RHSC; 232249259Sdim 233249259Sdim Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 234249259Sdim if (LHS == 0) 235249259Sdim return 0; 236249259Sdim return ConstantExpr::getOr(LHS, RHS); 237249259Sdim } 238249259Sdim case Instruction::And: { 239249259Sdim Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 240249259Sdim if (RHS == 0) 241249259Sdim return 0; 242249259Sdim 243249259Sdim // X & 0 -> 0. 244249259Sdim if (RHS->isNullValue()) 245249259Sdim return RHS; 246249259Sdim 247249259Sdim Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 248249259Sdim if (LHS == 0) 249249259Sdim return 0; 250249259Sdim return ConstantExpr::getAnd(LHS, RHS); 251249259Sdim } 252249259Sdim case Instruction::LShr: { 253249259Sdim ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 254249259Sdim if (Amt == 0) 255249259Sdim return 0; 256249259Sdim unsigned ShAmt = Amt->getZExtValue(); 257249259Sdim // Cannot analyze non-byte shifts. 258249259Sdim if ((ShAmt & 7) != 0) 259249259Sdim return 0; 260249259Sdim ShAmt >>= 3; 261249259Sdim 262249259Sdim // If the extract is known to be all zeros, return zero. 263249259Sdim if (ByteStart >= CSize-ShAmt) 264249259Sdim return Constant::getNullValue(IntegerType::get(CE->getContext(), 265249259Sdim ByteSize*8)); 266249259Sdim // If the extract is known to be fully in the input, extract it. 267249259Sdim if (ByteStart+ByteSize+ShAmt <= CSize) 268249259Sdim return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize); 269249259Sdim 270249259Sdim // TODO: Handle the 'partially zero' case. 271249259Sdim return 0; 272249259Sdim } 273249259Sdim 274249259Sdim case Instruction::Shl: { 275249259Sdim ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 276249259Sdim if (Amt == 0) 277249259Sdim return 0; 278249259Sdim unsigned ShAmt = Amt->getZExtValue(); 279249259Sdim // Cannot analyze non-byte shifts. 280249259Sdim if ((ShAmt & 7) != 0) 281249259Sdim return 0; 282249259Sdim ShAmt >>= 3; 283249259Sdim 284249259Sdim // If the extract is known to be all zeros, return zero. 285249259Sdim if (ByteStart+ByteSize <= ShAmt) 286249259Sdim return Constant::getNullValue(IntegerType::get(CE->getContext(), 287249259Sdim ByteSize*8)); 288249259Sdim // If the extract is known to be fully in the input, extract it. 289249259Sdim if (ByteStart >= ShAmt) 290249259Sdim return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize); 291249259Sdim 292249259Sdim // TODO: Handle the 'partially zero' case. 293249259Sdim return 0; 294249259Sdim } 295249259Sdim 296249259Sdim case Instruction::ZExt: { 297249259Sdim unsigned SrcBitSize = 298249259Sdim cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth(); 299249259Sdim 300249259Sdim // If extracting something that is completely zero, return 0. 301249259Sdim if (ByteStart*8 >= SrcBitSize) 302249259Sdim return Constant::getNullValue(IntegerType::get(CE->getContext(), 303249259Sdim ByteSize*8)); 304249259Sdim 305249259Sdim // If exactly extracting the input, return it. 306249259Sdim if (ByteStart == 0 && ByteSize*8 == SrcBitSize) 307249259Sdim return CE->getOperand(0); 308249259Sdim 309249259Sdim // If extracting something completely in the input, if if the input is a 310249259Sdim // multiple of 8 bits, recurse. 311249259Sdim if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize) 312249259Sdim return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize); 313249259Sdim 314249259Sdim // Otherwise, if extracting a subset of the input, which is not multiple of 315249259Sdim // 8 bits, do a shift and trunc to get the bits. 316249259Sdim if ((ByteStart+ByteSize)*8 < SrcBitSize) { 317249259Sdim assert((SrcBitSize&7) && "Shouldn't get byte sized case here"); 318249259Sdim Constant *Res = CE->getOperand(0); 319249259Sdim if (ByteStart) 320249259Sdim Res = ConstantExpr::getLShr(Res, 321249259Sdim ConstantInt::get(Res->getType(), ByteStart*8)); 322249259Sdim return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(), 323249259Sdim ByteSize*8)); 324249259Sdim } 325249259Sdim 326249259Sdim // TODO: Handle the 'partially zero' case. 327249259Sdim return 0; 328249259Sdim } 329249259Sdim } 330249259Sdim} 331249259Sdim 332249259Sdim/// getFoldedSizeOf - Return a ConstantExpr with type DestTy for sizeof 333249259Sdim/// on Ty, with any known factors factored out. If Folded is false, 334249259Sdim/// return null if no factoring was possible, to avoid endlessly 335249259Sdim/// bouncing an unfoldable expression back into the top-level folder. 336249259Sdim/// 337249259Sdimstatic Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, 338249259Sdim bool Folded) { 339249259Sdim if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 340249259Sdim Constant *N = ConstantInt::get(DestTy, ATy->getNumElements()); 341249259Sdim Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); 342249259Sdim return ConstantExpr::getNUWMul(E, N); 343249259Sdim } 344249259Sdim 345249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) 346249259Sdim if (!STy->isPacked()) { 347249259Sdim unsigned NumElems = STy->getNumElements(); 348249259Sdim // An empty struct has size zero. 349249259Sdim if (NumElems == 0) 350249259Sdim return ConstantExpr::getNullValue(DestTy); 351249259Sdim // Check for a struct with all members having the same size. 352249259Sdim Constant *MemberSize = 353249259Sdim getFoldedSizeOf(STy->getElementType(0), DestTy, true); 354249259Sdim bool AllSame = true; 355249259Sdim for (unsigned i = 1; i != NumElems; ++i) 356249259Sdim if (MemberSize != 357249259Sdim getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { 358249259Sdim AllSame = false; 359249259Sdim break; 360249259Sdim } 361249259Sdim if (AllSame) { 362249259Sdim Constant *N = ConstantInt::get(DestTy, NumElems); 363249259Sdim return ConstantExpr::getNUWMul(MemberSize, N); 364249259Sdim } 365249259Sdim } 366249259Sdim 367249259Sdim // Pointer size doesn't depend on the pointee type, so canonicalize them 368249259Sdim // to an arbitrary pointee. 369249259Sdim if (PointerType *PTy = dyn_cast<PointerType>(Ty)) 370249259Sdim if (!PTy->getElementType()->isIntegerTy(1)) 371249259Sdim return 372249259Sdim getFoldedSizeOf(PointerType::get(IntegerType::get(PTy->getContext(), 1), 373249259Sdim PTy->getAddressSpace()), 374249259Sdim DestTy, true); 375249259Sdim 376249259Sdim // If there's no interesting folding happening, bail so that we don't create 377249259Sdim // a constant that looks like it needs folding but really doesn't. 378249259Sdim if (!Folded) 379249259Sdim return 0; 380249259Sdim 381249259Sdim // Base case: Get a regular sizeof expression. 382249259Sdim Constant *C = ConstantExpr::getSizeOf(Ty); 383249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 384249259Sdim DestTy, false), 385249259Sdim C, DestTy); 386249259Sdim return C; 387249259Sdim} 388249259Sdim 389249259Sdim/// getFoldedAlignOf - Return a ConstantExpr with type DestTy for alignof 390249259Sdim/// on Ty, with any known factors factored out. If Folded is false, 391249259Sdim/// return null if no factoring was possible, to avoid endlessly 392249259Sdim/// bouncing an unfoldable expression back into the top-level folder. 393249259Sdim/// 394249259Sdimstatic Constant *getFoldedAlignOf(Type *Ty, Type *DestTy, 395249259Sdim bool Folded) { 396249259Sdim // The alignment of an array is equal to the alignment of the 397249259Sdim // array element. Note that this is not always true for vectors. 398249259Sdim if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 399249259Sdim Constant *C = ConstantExpr::getAlignOf(ATy->getElementType()); 400249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 401249259Sdim DestTy, 402249259Sdim false), 403249259Sdim C, DestTy); 404249259Sdim return C; 405249259Sdim } 406249259Sdim 407249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) { 408249259Sdim // Packed structs always have an alignment of 1. 409249259Sdim if (STy->isPacked()) 410249259Sdim return ConstantInt::get(DestTy, 1); 411249259Sdim 412249259Sdim // Otherwise, struct alignment is the maximum alignment of any member. 413249259Sdim // Without target data, we can't compare much, but we can check to see 414249259Sdim // if all the members have the same alignment. 415249259Sdim unsigned NumElems = STy->getNumElements(); 416249259Sdim // An empty struct has minimal alignment. 417249259Sdim if (NumElems == 0) 418249259Sdim return ConstantInt::get(DestTy, 1); 419249259Sdim // Check for a struct with all members having the same alignment. 420249259Sdim Constant *MemberAlign = 421249259Sdim getFoldedAlignOf(STy->getElementType(0), DestTy, true); 422249259Sdim bool AllSame = true; 423249259Sdim for (unsigned i = 1; i != NumElems; ++i) 424249259Sdim if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) { 425249259Sdim AllSame = false; 426249259Sdim break; 427249259Sdim } 428249259Sdim if (AllSame) 429249259Sdim return MemberAlign; 430249259Sdim } 431249259Sdim 432249259Sdim // Pointer alignment doesn't depend on the pointee type, so canonicalize them 433249259Sdim // to an arbitrary pointee. 434249259Sdim if (PointerType *PTy = dyn_cast<PointerType>(Ty)) 435249259Sdim if (!PTy->getElementType()->isIntegerTy(1)) 436249259Sdim return 437249259Sdim getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(), 438249259Sdim 1), 439249259Sdim PTy->getAddressSpace()), 440249259Sdim DestTy, true); 441249259Sdim 442249259Sdim // If there's no interesting folding happening, bail so that we don't create 443249259Sdim // a constant that looks like it needs folding but really doesn't. 444249259Sdim if (!Folded) 445249259Sdim return 0; 446249259Sdim 447249259Sdim // Base case: Get a regular alignof expression. 448249259Sdim Constant *C = ConstantExpr::getAlignOf(Ty); 449249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 450249259Sdim DestTy, false), 451249259Sdim C, DestTy); 452249259Sdim return C; 453249259Sdim} 454249259Sdim 455249259Sdim/// getFoldedOffsetOf - Return a ConstantExpr with type DestTy for offsetof 456249259Sdim/// on Ty and FieldNo, with any known factors factored out. If Folded is false, 457249259Sdim/// return null if no factoring was possible, to avoid endlessly 458249259Sdim/// bouncing an unfoldable expression back into the top-level folder. 459249259Sdim/// 460249259Sdimstatic Constant *getFoldedOffsetOf(Type *Ty, Constant *FieldNo, 461249259Sdim Type *DestTy, 462249259Sdim bool Folded) { 463249259Sdim if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 464249259Sdim Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false, 465249259Sdim DestTy, false), 466249259Sdim FieldNo, DestTy); 467249259Sdim Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); 468249259Sdim return ConstantExpr::getNUWMul(E, N); 469249259Sdim } 470249259Sdim 471249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) 472249259Sdim if (!STy->isPacked()) { 473249259Sdim unsigned NumElems = STy->getNumElements(); 474249259Sdim // An empty struct has no members. 475249259Sdim if (NumElems == 0) 476249259Sdim return 0; 477249259Sdim // Check for a struct with all members having the same size. 478249259Sdim Constant *MemberSize = 479249259Sdim getFoldedSizeOf(STy->getElementType(0), DestTy, true); 480249259Sdim bool AllSame = true; 481249259Sdim for (unsigned i = 1; i != NumElems; ++i) 482249259Sdim if (MemberSize != 483249259Sdim getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { 484249259Sdim AllSame = false; 485249259Sdim break; 486249259Sdim } 487249259Sdim if (AllSame) { 488249259Sdim Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, 489249259Sdim false, 490249259Sdim DestTy, 491249259Sdim false), 492249259Sdim FieldNo, DestTy); 493249259Sdim return ConstantExpr::getNUWMul(MemberSize, N); 494249259Sdim } 495249259Sdim } 496249259Sdim 497249259Sdim // If there's no interesting folding happening, bail so that we don't create 498249259Sdim // a constant that looks like it needs folding but really doesn't. 499249259Sdim if (!Folded) 500249259Sdim return 0; 501249259Sdim 502249259Sdim // Base case: Get a regular offsetof expression. 503249259Sdim Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo); 504249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 505249259Sdim DestTy, false), 506249259Sdim C, DestTy); 507249259Sdim return C; 508249259Sdim} 509249259Sdim 510249259SdimConstant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, 511249259Sdim Type *DestTy) { 512249259Sdim if (isa<UndefValue>(V)) { 513249259Sdim // zext(undef) = 0, because the top bits will be zero. 514249259Sdim // sext(undef) = 0, because the top bits will all be the same. 515249259Sdim // [us]itofp(undef) = 0, because the result value is bounded. 516249259Sdim if (opc == Instruction::ZExt || opc == Instruction::SExt || 517249259Sdim opc == Instruction::UIToFP || opc == Instruction::SIToFP) 518249259Sdim return Constant::getNullValue(DestTy); 519249259Sdim return UndefValue::get(DestTy); 520249259Sdim } 521249259Sdim 522249259Sdim if (V->isNullValue() && !DestTy->isX86_MMXTy()) 523249259Sdim return Constant::getNullValue(DestTy); 524249259Sdim 525249259Sdim // If the cast operand is a constant expression, there's a few things we can 526249259Sdim // do to try to simplify it. 527249259Sdim if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 528249259Sdim if (CE->isCast()) { 529249259Sdim // Try hard to fold cast of cast because they are often eliminable. 530249259Sdim if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) 531249259Sdim return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); 532249259Sdim } else if (CE->getOpcode() == Instruction::GetElementPtr) { 533249259Sdim // If all of the indexes in the GEP are null values, there is no pointer 534249259Sdim // adjustment going on. We might as well cast the source pointer. 535249259Sdim bool isAllNull = true; 536249259Sdim for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) 537249259Sdim if (!CE->getOperand(i)->isNullValue()) { 538249259Sdim isAllNull = false; 539249259Sdim break; 540249259Sdim } 541249259Sdim if (isAllNull) 542249259Sdim // This is casting one pointer type to another, always BitCast 543249259Sdim return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); 544249259Sdim } 545249259Sdim } 546249259Sdim 547249259Sdim // If the cast operand is a constant vector, perform the cast by 548249259Sdim // operating on each element. In the cast of bitcasts, the element 549249259Sdim // count may be mismatched; don't attempt to handle that here. 550249259Sdim if ((isa<ConstantVector>(V) || isa<ConstantDataVector>(V)) && 551249259Sdim DestTy->isVectorTy() && 552249259Sdim DestTy->getVectorNumElements() == V->getType()->getVectorNumElements()) { 553249259Sdim SmallVector<Constant*, 16> res; 554249259Sdim VectorType *DestVecTy = cast<VectorType>(DestTy); 555249259Sdim Type *DstEltTy = DestVecTy->getElementType(); 556249259Sdim Type *Ty = IntegerType::get(V->getContext(), 32); 557249259Sdim for (unsigned i = 0, e = V->getType()->getVectorNumElements(); i != e; ++i) { 558249259Sdim Constant *C = 559249259Sdim ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i)); 560249259Sdim res.push_back(ConstantExpr::getCast(opc, C, DstEltTy)); 561249259Sdim } 562249259Sdim return ConstantVector::get(res); 563249259Sdim } 564249259Sdim 565249259Sdim // We actually have to do a cast now. Perform the cast according to the 566249259Sdim // opcode specified. 567249259Sdim switch (opc) { 568249259Sdim default: 569249259Sdim llvm_unreachable("Failed to cast constant expression"); 570249259Sdim case Instruction::FPTrunc: 571249259Sdim case Instruction::FPExt: 572249259Sdim if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 573249259Sdim bool ignored; 574249259Sdim APFloat Val = FPC->getValueAPF(); 575249259Sdim Val.convert(DestTy->isHalfTy() ? APFloat::IEEEhalf : 576249259Sdim DestTy->isFloatTy() ? APFloat::IEEEsingle : 577249259Sdim DestTy->isDoubleTy() ? APFloat::IEEEdouble : 578249259Sdim DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended : 579249259Sdim DestTy->isFP128Ty() ? APFloat::IEEEquad : 580249259Sdim DestTy->isPPC_FP128Ty() ? APFloat::PPCDoubleDouble : 581249259Sdim APFloat::Bogus, 582249259Sdim APFloat::rmNearestTiesToEven, &ignored); 583249259Sdim return ConstantFP::get(V->getContext(), Val); 584249259Sdim } 585249259Sdim return 0; // Can't fold. 586249259Sdim case Instruction::FPToUI: 587249259Sdim case Instruction::FPToSI: 588249259Sdim if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 589249259Sdim const APFloat &V = FPC->getValueAPF(); 590249259Sdim bool ignored; 591249259Sdim uint64_t x[2]; 592249259Sdim uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 593249259Sdim (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, 594249259Sdim APFloat::rmTowardZero, &ignored); 595249259Sdim APInt Val(DestBitWidth, x); 596249259Sdim return ConstantInt::get(FPC->getContext(), Val); 597249259Sdim } 598249259Sdim return 0; // Can't fold. 599249259Sdim case Instruction::IntToPtr: //always treated as unsigned 600249259Sdim if (V->isNullValue()) // Is it an integral null value? 601249259Sdim return ConstantPointerNull::get(cast<PointerType>(DestTy)); 602249259Sdim return 0; // Other pointer types cannot be casted 603249259Sdim case Instruction::PtrToInt: // always treated as unsigned 604249259Sdim // Is it a null pointer value? 605249259Sdim if (V->isNullValue()) 606249259Sdim return ConstantInt::get(DestTy, 0); 607249259Sdim // If this is a sizeof-like expression, pull out multiplications by 608249259Sdim // known factors to expose them to subsequent folding. If it's an 609249259Sdim // alignof-like expression, factor out known factors. 610249259Sdim if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 611249259Sdim if (CE->getOpcode() == Instruction::GetElementPtr && 612249259Sdim CE->getOperand(0)->isNullValue()) { 613249259Sdim Type *Ty = 614249259Sdim cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); 615249259Sdim if (CE->getNumOperands() == 2) { 616249259Sdim // Handle a sizeof-like expression. 617249259Sdim Constant *Idx = CE->getOperand(1); 618249259Sdim bool isOne = isa<ConstantInt>(Idx) && cast<ConstantInt>(Idx)->isOne(); 619249259Sdim if (Constant *C = getFoldedSizeOf(Ty, DestTy, !isOne)) { 620249259Sdim Idx = ConstantExpr::getCast(CastInst::getCastOpcode(Idx, true, 621249259Sdim DestTy, false), 622249259Sdim Idx, DestTy); 623249259Sdim return ConstantExpr::getMul(C, Idx); 624249259Sdim } 625249259Sdim } else if (CE->getNumOperands() == 3 && 626249259Sdim CE->getOperand(1)->isNullValue()) { 627249259Sdim // Handle an alignof-like expression. 628249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) 629249259Sdim if (!STy->isPacked()) { 630249259Sdim ConstantInt *CI = cast<ConstantInt>(CE->getOperand(2)); 631249259Sdim if (CI->isOne() && 632249259Sdim STy->getNumElements() == 2 && 633249259Sdim STy->getElementType(0)->isIntegerTy(1)) { 634249259Sdim return getFoldedAlignOf(STy->getElementType(1), DestTy, false); 635249259Sdim } 636249259Sdim } 637249259Sdim // Handle an offsetof-like expression. 638249259Sdim if (Ty->isStructTy() || Ty->isArrayTy()) { 639249259Sdim if (Constant *C = getFoldedOffsetOf(Ty, CE->getOperand(2), 640249259Sdim DestTy, false)) 641249259Sdim return C; 642249259Sdim } 643249259Sdim } 644249259Sdim } 645249259Sdim // Other pointer types cannot be casted 646249259Sdim return 0; 647249259Sdim case Instruction::UIToFP: 648249259Sdim case Instruction::SIToFP: 649249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 650249259Sdim APInt api = CI->getValue(); 651249259Sdim APFloat apf(DestTy->getFltSemantics(), 652249259Sdim APInt::getNullValue(DestTy->getPrimitiveSizeInBits())); 653249259Sdim (void)apf.convertFromAPInt(api, 654249259Sdim opc==Instruction::SIToFP, 655249259Sdim APFloat::rmNearestTiesToEven); 656249259Sdim return ConstantFP::get(V->getContext(), apf); 657249259Sdim } 658249259Sdim return 0; 659249259Sdim case Instruction::ZExt: 660249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 661249259Sdim uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 662249259Sdim return ConstantInt::get(V->getContext(), 663249259Sdim CI->getValue().zext(BitWidth)); 664249259Sdim } 665249259Sdim return 0; 666249259Sdim case Instruction::SExt: 667249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 668249259Sdim uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 669249259Sdim return ConstantInt::get(V->getContext(), 670249259Sdim CI->getValue().sext(BitWidth)); 671249259Sdim } 672249259Sdim return 0; 673249259Sdim case Instruction::Trunc: { 674249259Sdim uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 675249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 676249259Sdim return ConstantInt::get(V->getContext(), 677249259Sdim CI->getValue().trunc(DestBitWidth)); 678249259Sdim } 679249259Sdim 680249259Sdim // The input must be a constantexpr. See if we can simplify this based on 681249259Sdim // the bytes we are demanding. Only do this if the source and dest are an 682249259Sdim // even multiple of a byte. 683249259Sdim if ((DestBitWidth & 7) == 0 && 684249259Sdim (cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0) 685249259Sdim if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8)) 686249259Sdim return Res; 687249259Sdim 688249259Sdim return 0; 689249259Sdim } 690249259Sdim case Instruction::BitCast: 691249259Sdim return FoldBitCast(V, DestTy); 692263508Sdim case Instruction::AddrSpaceCast: 693263508Sdim return 0; 694249259Sdim } 695249259Sdim} 696249259Sdim 697249259SdimConstant *llvm::ConstantFoldSelectInstruction(Constant *Cond, 698249259Sdim Constant *V1, Constant *V2) { 699249259Sdim // Check for i1 and vector true/false conditions. 700249259Sdim if (Cond->isNullValue()) return V2; 701249259Sdim if (Cond->isAllOnesValue()) return V1; 702249259Sdim 703249259Sdim // If the condition is a vector constant, fold the result elementwise. 704249259Sdim if (ConstantVector *CondV = dyn_cast<ConstantVector>(Cond)) { 705249259Sdim SmallVector<Constant*, 16> Result; 706249259Sdim Type *Ty = IntegerType::get(CondV->getContext(), 32); 707249259Sdim for (unsigned i = 0, e = V1->getType()->getVectorNumElements(); i != e;++i){ 708249259Sdim ConstantInt *Cond = dyn_cast<ConstantInt>(CondV->getOperand(i)); 709249259Sdim if (Cond == 0) break; 710249259Sdim 711249259Sdim Constant *V = Cond->isNullValue() ? V2 : V1; 712249259Sdim Constant *Res = ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i)); 713249259Sdim Result.push_back(Res); 714249259Sdim } 715249259Sdim 716249259Sdim // If we were able to build the vector, return it. 717249259Sdim if (Result.size() == V1->getType()->getVectorNumElements()) 718249259Sdim return ConstantVector::get(Result); 719249259Sdim } 720249259Sdim 721249259Sdim if (isa<UndefValue>(Cond)) { 722249259Sdim if (isa<UndefValue>(V1)) return V1; 723249259Sdim return V2; 724249259Sdim } 725249259Sdim if (isa<UndefValue>(V1)) return V2; 726249259Sdim if (isa<UndefValue>(V2)) return V1; 727249259Sdim if (V1 == V2) return V1; 728249259Sdim 729249259Sdim if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) { 730249259Sdim if (TrueVal->getOpcode() == Instruction::Select) 731249259Sdim if (TrueVal->getOperand(0) == Cond) 732249259Sdim return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2); 733249259Sdim } 734249259Sdim if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) { 735249259Sdim if (FalseVal->getOpcode() == Instruction::Select) 736249259Sdim if (FalseVal->getOperand(0) == Cond) 737249259Sdim return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2)); 738249259Sdim } 739249259Sdim 740249259Sdim return 0; 741249259Sdim} 742249259Sdim 743249259SdimConstant *llvm::ConstantFoldExtractElementInstruction(Constant *Val, 744249259Sdim Constant *Idx) { 745249259Sdim if (isa<UndefValue>(Val)) // ee(undef, x) -> undef 746249259Sdim return UndefValue::get(Val->getType()->getVectorElementType()); 747249259Sdim if (Val->isNullValue()) // ee(zero, x) -> zero 748249259Sdim return Constant::getNullValue(Val->getType()->getVectorElementType()); 749249259Sdim // ee({w,x,y,z}, undef) -> undef 750249259Sdim if (isa<UndefValue>(Idx)) 751249259Sdim return UndefValue::get(Val->getType()->getVectorElementType()); 752249259Sdim 753249259Sdim if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { 754249259Sdim uint64_t Index = CIdx->getZExtValue(); 755249259Sdim // ee({w,x,y,z}, wrong_value) -> undef 756249259Sdim if (Index >= Val->getType()->getVectorNumElements()) 757249259Sdim return UndefValue::get(Val->getType()->getVectorElementType()); 758249259Sdim return Val->getAggregateElement(Index); 759249259Sdim } 760249259Sdim return 0; 761249259Sdim} 762249259Sdim 763249259SdimConstant *llvm::ConstantFoldInsertElementInstruction(Constant *Val, 764249259Sdim Constant *Elt, 765249259Sdim Constant *Idx) { 766249259Sdim ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); 767249259Sdim if (!CIdx) return 0; 768249259Sdim const APInt &IdxVal = CIdx->getValue(); 769249259Sdim 770249259Sdim SmallVector<Constant*, 16> Result; 771249259Sdim Type *Ty = IntegerType::get(Val->getContext(), 32); 772249259Sdim for (unsigned i = 0, e = Val->getType()->getVectorNumElements(); i != e; ++i){ 773249259Sdim if (i == IdxVal) { 774249259Sdim Result.push_back(Elt); 775249259Sdim continue; 776249259Sdim } 777249259Sdim 778249259Sdim Constant *C = 779249259Sdim ConstantExpr::getExtractElement(Val, ConstantInt::get(Ty, i)); 780249259Sdim Result.push_back(C); 781249259Sdim } 782249259Sdim 783249259Sdim return ConstantVector::get(Result); 784249259Sdim} 785249259Sdim 786249259SdimConstant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1, 787249259Sdim Constant *V2, 788249259Sdim Constant *Mask) { 789249259Sdim unsigned MaskNumElts = Mask->getType()->getVectorNumElements(); 790249259Sdim Type *EltTy = V1->getType()->getVectorElementType(); 791249259Sdim 792249259Sdim // Undefined shuffle mask -> undefined value. 793249259Sdim if (isa<UndefValue>(Mask)) 794249259Sdim return UndefValue::get(VectorType::get(EltTy, MaskNumElts)); 795249259Sdim 796249259Sdim // Don't break the bitcode reader hack. 797249259Sdim if (isa<ConstantExpr>(Mask)) return 0; 798249259Sdim 799249259Sdim unsigned SrcNumElts = V1->getType()->getVectorNumElements(); 800249259Sdim 801249259Sdim // Loop over the shuffle mask, evaluating each element. 802249259Sdim SmallVector<Constant*, 32> Result; 803249259Sdim for (unsigned i = 0; i != MaskNumElts; ++i) { 804249259Sdim int Elt = ShuffleVectorInst::getMaskValue(Mask, i); 805249259Sdim if (Elt == -1) { 806249259Sdim Result.push_back(UndefValue::get(EltTy)); 807249259Sdim continue; 808249259Sdim } 809249259Sdim Constant *InElt; 810249259Sdim if (unsigned(Elt) >= SrcNumElts*2) 811249259Sdim InElt = UndefValue::get(EltTy); 812249259Sdim else if (unsigned(Elt) >= SrcNumElts) { 813249259Sdim Type *Ty = IntegerType::get(V2->getContext(), 32); 814249259Sdim InElt = 815249259Sdim ConstantExpr::getExtractElement(V2, 816249259Sdim ConstantInt::get(Ty, Elt - SrcNumElts)); 817249259Sdim } else { 818249259Sdim Type *Ty = IntegerType::get(V1->getContext(), 32); 819249259Sdim InElt = ConstantExpr::getExtractElement(V1, ConstantInt::get(Ty, Elt)); 820249259Sdim } 821249259Sdim Result.push_back(InElt); 822249259Sdim } 823249259Sdim 824249259Sdim return ConstantVector::get(Result); 825249259Sdim} 826249259Sdim 827249259SdimConstant *llvm::ConstantFoldExtractValueInstruction(Constant *Agg, 828249259Sdim ArrayRef<unsigned> Idxs) { 829249259Sdim // Base case: no indices, so return the entire value. 830249259Sdim if (Idxs.empty()) 831249259Sdim return Agg; 832249259Sdim 833249259Sdim if (Constant *C = Agg->getAggregateElement(Idxs[0])) 834249259Sdim return ConstantFoldExtractValueInstruction(C, Idxs.slice(1)); 835249259Sdim 836249259Sdim return 0; 837249259Sdim} 838249259Sdim 839249259SdimConstant *llvm::ConstantFoldInsertValueInstruction(Constant *Agg, 840249259Sdim Constant *Val, 841249259Sdim ArrayRef<unsigned> Idxs) { 842249259Sdim // Base case: no indices, so replace the entire value. 843249259Sdim if (Idxs.empty()) 844249259Sdim return Val; 845249259Sdim 846249259Sdim unsigned NumElts; 847249259Sdim if (StructType *ST = dyn_cast<StructType>(Agg->getType())) 848249259Sdim NumElts = ST->getNumElements(); 849249259Sdim else if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) 850249259Sdim NumElts = AT->getNumElements(); 851249259Sdim else 852249259Sdim NumElts = Agg->getType()->getVectorNumElements(); 853249259Sdim 854249259Sdim SmallVector<Constant*, 32> Result; 855249259Sdim for (unsigned i = 0; i != NumElts; ++i) { 856249259Sdim Constant *C = Agg->getAggregateElement(i); 857249259Sdim if (C == 0) return 0; 858249259Sdim 859249259Sdim if (Idxs[0] == i) 860249259Sdim C = ConstantFoldInsertValueInstruction(C, Val, Idxs.slice(1)); 861249259Sdim 862249259Sdim Result.push_back(C); 863249259Sdim } 864249259Sdim 865249259Sdim if (StructType *ST = dyn_cast<StructType>(Agg->getType())) 866249259Sdim return ConstantStruct::get(ST, Result); 867249259Sdim if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) 868249259Sdim return ConstantArray::get(AT, Result); 869249259Sdim return ConstantVector::get(Result); 870249259Sdim} 871249259Sdim 872249259Sdim 873249259SdimConstant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, 874249259Sdim Constant *C1, Constant *C2) { 875249259Sdim // Handle UndefValue up front. 876249259Sdim if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 877249259Sdim switch (Opcode) { 878249259Sdim case Instruction::Xor: 879249259Sdim if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) 880249259Sdim // Handle undef ^ undef -> 0 special case. This is a common 881249259Sdim // idiom (misuse). 882249259Sdim return Constant::getNullValue(C1->getType()); 883249259Sdim // Fallthrough 884249259Sdim case Instruction::Add: 885249259Sdim case Instruction::Sub: 886249259Sdim return UndefValue::get(C1->getType()); 887249259Sdim case Instruction::And: 888249259Sdim if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef & undef -> undef 889249259Sdim return C1; 890249259Sdim return Constant::getNullValue(C1->getType()); // undef & X -> 0 891249259Sdim case Instruction::Mul: { 892249259Sdim ConstantInt *CI; 893249259Sdim // X * undef -> undef if X is odd or undef 894249259Sdim if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) || 895249259Sdim ((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) || 896249259Sdim (isa<UndefValue>(C1) && isa<UndefValue>(C2))) 897249259Sdim return UndefValue::get(C1->getType()); 898249259Sdim 899249259Sdim // X * undef -> 0 otherwise 900249259Sdim return Constant::getNullValue(C1->getType()); 901249259Sdim } 902249259Sdim case Instruction::UDiv: 903249259Sdim case Instruction::SDiv: 904249259Sdim // undef / 1 -> undef 905249259Sdim if (Opcode == Instruction::UDiv || Opcode == Instruction::SDiv) 906249259Sdim if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) 907249259Sdim if (CI2->isOne()) 908249259Sdim return C1; 909249259Sdim // FALL THROUGH 910249259Sdim case Instruction::URem: 911249259Sdim case Instruction::SRem: 912249259Sdim if (!isa<UndefValue>(C2)) // undef / X -> 0 913249259Sdim return Constant::getNullValue(C1->getType()); 914249259Sdim return C2; // X / undef -> undef 915249259Sdim case Instruction::Or: // X | undef -> -1 916249259Sdim if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef 917249259Sdim return C1; 918249259Sdim return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0 919249259Sdim case Instruction::LShr: 920249259Sdim if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) 921249259Sdim return C1; // undef lshr undef -> undef 922249259Sdim return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 923249259Sdim // undef lshr X -> 0 924249259Sdim case Instruction::AShr: 925249259Sdim if (!isa<UndefValue>(C2)) // undef ashr X --> all ones 926249259Sdim return Constant::getAllOnesValue(C1->getType()); 927249259Sdim else if (isa<UndefValue>(C1)) 928249259Sdim return C1; // undef ashr undef -> undef 929249259Sdim else 930249259Sdim return C1; // X ashr undef --> X 931249259Sdim case Instruction::Shl: 932249259Sdim if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) 933249259Sdim return C1; // undef shl undef -> undef 934249259Sdim // undef << X -> 0 or X << undef -> 0 935249259Sdim return Constant::getNullValue(C1->getType()); 936249259Sdim } 937249259Sdim } 938249259Sdim 939249259Sdim // Handle simplifications when the RHS is a constant int. 940249259Sdim if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 941249259Sdim switch (Opcode) { 942249259Sdim case Instruction::Add: 943249259Sdim if (CI2->equalsInt(0)) return C1; // X + 0 == X 944249259Sdim break; 945249259Sdim case Instruction::Sub: 946249259Sdim if (CI2->equalsInt(0)) return C1; // X - 0 == X 947249259Sdim break; 948249259Sdim case Instruction::Mul: 949249259Sdim if (CI2->equalsInt(0)) return C2; // X * 0 == 0 950249259Sdim if (CI2->equalsInt(1)) 951249259Sdim return C1; // X * 1 == X 952249259Sdim break; 953249259Sdim case Instruction::UDiv: 954249259Sdim case Instruction::SDiv: 955249259Sdim if (CI2->equalsInt(1)) 956249259Sdim return C1; // X / 1 == X 957249259Sdim if (CI2->equalsInt(0)) 958249259Sdim return UndefValue::get(CI2->getType()); // X / 0 == undef 959249259Sdim break; 960249259Sdim case Instruction::URem: 961249259Sdim case Instruction::SRem: 962249259Sdim if (CI2->equalsInt(1)) 963249259Sdim return Constant::getNullValue(CI2->getType()); // X % 1 == 0 964249259Sdim if (CI2->equalsInt(0)) 965249259Sdim return UndefValue::get(CI2->getType()); // X % 0 == undef 966249259Sdim break; 967249259Sdim case Instruction::And: 968249259Sdim if (CI2->isZero()) return C2; // X & 0 == 0 969249259Sdim if (CI2->isAllOnesValue()) 970249259Sdim return C1; // X & -1 == X 971249259Sdim 972249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 973249259Sdim // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) 974249259Sdim if (CE1->getOpcode() == Instruction::ZExt) { 975249259Sdim unsigned DstWidth = CI2->getType()->getBitWidth(); 976249259Sdim unsigned SrcWidth = 977249259Sdim CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); 978249259Sdim APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); 979249259Sdim if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) 980249259Sdim return C1; 981249259Sdim } 982249259Sdim 983249259Sdim // If and'ing the address of a global with a constant, fold it. 984249259Sdim if (CE1->getOpcode() == Instruction::PtrToInt && 985249259Sdim isa<GlobalValue>(CE1->getOperand(0))) { 986249259Sdim GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0)); 987249259Sdim 988249259Sdim // Functions are at least 4-byte aligned. 989249259Sdim unsigned GVAlign = GV->getAlignment(); 990249259Sdim if (isa<Function>(GV)) 991249259Sdim GVAlign = std::max(GVAlign, 4U); 992249259Sdim 993249259Sdim if (GVAlign > 1) { 994249259Sdim unsigned DstWidth = CI2->getType()->getBitWidth(); 995249259Sdim unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign)); 996249259Sdim APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth)); 997249259Sdim 998249259Sdim // If checking bits we know are clear, return zero. 999249259Sdim if ((CI2->getValue() & BitsNotSet) == CI2->getValue()) 1000249259Sdim return Constant::getNullValue(CI2->getType()); 1001249259Sdim } 1002249259Sdim } 1003249259Sdim } 1004249259Sdim break; 1005249259Sdim case Instruction::Or: 1006249259Sdim if (CI2->equalsInt(0)) return C1; // X | 0 == X 1007249259Sdim if (CI2->isAllOnesValue()) 1008249259Sdim return C2; // X | -1 == -1 1009249259Sdim break; 1010249259Sdim case Instruction::Xor: 1011249259Sdim if (CI2->equalsInt(0)) return C1; // X ^ 0 == X 1012249259Sdim 1013249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1014249259Sdim switch (CE1->getOpcode()) { 1015249259Sdim default: break; 1016249259Sdim case Instruction::ICmp: 1017249259Sdim case Instruction::FCmp: 1018249259Sdim // cmp pred ^ true -> cmp !pred 1019249259Sdim assert(CI2->equalsInt(1)); 1020249259Sdim CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate(); 1021249259Sdim pred = CmpInst::getInversePredicate(pred); 1022249259Sdim return ConstantExpr::getCompare(pred, CE1->getOperand(0), 1023249259Sdim CE1->getOperand(1)); 1024249259Sdim } 1025249259Sdim } 1026249259Sdim break; 1027249259Sdim case Instruction::AShr: 1028249259Sdim // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 1029249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) 1030249259Sdim if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. 1031249259Sdim return ConstantExpr::getLShr(C1, C2); 1032249259Sdim break; 1033249259Sdim } 1034249259Sdim } else if (isa<ConstantInt>(C1)) { 1035249259Sdim // If C1 is a ConstantInt and C2 is not, swap the operands. 1036249259Sdim if (Instruction::isCommutative(Opcode)) 1037249259Sdim return ConstantExpr::get(Opcode, C2, C1); 1038249259Sdim } 1039249259Sdim 1040249259Sdim // At this point we know neither constant is an UndefValue. 1041249259Sdim if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { 1042249259Sdim if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 1043249259Sdim const APInt &C1V = CI1->getValue(); 1044249259Sdim const APInt &C2V = CI2->getValue(); 1045249259Sdim switch (Opcode) { 1046249259Sdim default: 1047249259Sdim break; 1048249259Sdim case Instruction::Add: 1049249259Sdim return ConstantInt::get(CI1->getContext(), C1V + C2V); 1050249259Sdim case Instruction::Sub: 1051249259Sdim return ConstantInt::get(CI1->getContext(), C1V - C2V); 1052249259Sdim case Instruction::Mul: 1053249259Sdim return ConstantInt::get(CI1->getContext(), C1V * C2V); 1054249259Sdim case Instruction::UDiv: 1055249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1056249259Sdim return ConstantInt::get(CI1->getContext(), C1V.udiv(C2V)); 1057249259Sdim case Instruction::SDiv: 1058249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1059249259Sdim if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 1060249259Sdim return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef 1061249259Sdim return ConstantInt::get(CI1->getContext(), C1V.sdiv(C2V)); 1062249259Sdim case Instruction::URem: 1063249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1064249259Sdim return ConstantInt::get(CI1->getContext(), C1V.urem(C2V)); 1065249259Sdim case Instruction::SRem: 1066249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1067249259Sdim if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 1068249259Sdim return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef 1069249259Sdim return ConstantInt::get(CI1->getContext(), C1V.srem(C2V)); 1070249259Sdim case Instruction::And: 1071249259Sdim return ConstantInt::get(CI1->getContext(), C1V & C2V); 1072249259Sdim case Instruction::Or: 1073249259Sdim return ConstantInt::get(CI1->getContext(), C1V | C2V); 1074249259Sdim case Instruction::Xor: 1075249259Sdim return ConstantInt::get(CI1->getContext(), C1V ^ C2V); 1076249259Sdim case Instruction::Shl: { 1077249259Sdim uint32_t shiftAmt = C2V.getZExtValue(); 1078249259Sdim if (shiftAmt < C1V.getBitWidth()) 1079249259Sdim return ConstantInt::get(CI1->getContext(), C1V.shl(shiftAmt)); 1080249259Sdim else 1081249259Sdim return UndefValue::get(C1->getType()); // too big shift is undef 1082249259Sdim } 1083249259Sdim case Instruction::LShr: { 1084249259Sdim uint32_t shiftAmt = C2V.getZExtValue(); 1085249259Sdim if (shiftAmt < C1V.getBitWidth()) 1086249259Sdim return ConstantInt::get(CI1->getContext(), C1V.lshr(shiftAmt)); 1087249259Sdim else 1088249259Sdim return UndefValue::get(C1->getType()); // too big shift is undef 1089249259Sdim } 1090249259Sdim case Instruction::AShr: { 1091249259Sdim uint32_t shiftAmt = C2V.getZExtValue(); 1092249259Sdim if (shiftAmt < C1V.getBitWidth()) 1093249259Sdim return ConstantInt::get(CI1->getContext(), C1V.ashr(shiftAmt)); 1094249259Sdim else 1095249259Sdim return UndefValue::get(C1->getType()); // too big shift is undef 1096249259Sdim } 1097249259Sdim } 1098249259Sdim } 1099249259Sdim 1100249259Sdim switch (Opcode) { 1101249259Sdim case Instruction::SDiv: 1102249259Sdim case Instruction::UDiv: 1103249259Sdim case Instruction::URem: 1104249259Sdim case Instruction::SRem: 1105249259Sdim case Instruction::LShr: 1106249259Sdim case Instruction::AShr: 1107249259Sdim case Instruction::Shl: 1108249259Sdim if (CI1->equalsInt(0)) return C1; 1109249259Sdim break; 1110249259Sdim default: 1111249259Sdim break; 1112249259Sdim } 1113249259Sdim } else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { 1114249259Sdim if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { 1115249259Sdim APFloat C1V = CFP1->getValueAPF(); 1116249259Sdim APFloat C2V = CFP2->getValueAPF(); 1117249259Sdim APFloat C3V = C1V; // copy for modification 1118249259Sdim switch (Opcode) { 1119249259Sdim default: 1120249259Sdim break; 1121249259Sdim case Instruction::FAdd: 1122249259Sdim (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); 1123249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1124249259Sdim case Instruction::FSub: 1125249259Sdim (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); 1126249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1127249259Sdim case Instruction::FMul: 1128249259Sdim (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); 1129249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1130249259Sdim case Instruction::FDiv: 1131249259Sdim (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); 1132249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1133249259Sdim case Instruction::FRem: 1134249259Sdim (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven); 1135249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1136249259Sdim } 1137249259Sdim } 1138249259Sdim } else if (VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { 1139249259Sdim // Perform elementwise folding. 1140249259Sdim SmallVector<Constant*, 16> Result; 1141249259Sdim Type *Ty = IntegerType::get(VTy->getContext(), 32); 1142249259Sdim for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1143249259Sdim Constant *LHS = 1144249259Sdim ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, i)); 1145249259Sdim Constant *RHS = 1146249259Sdim ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, i)); 1147249259Sdim 1148249259Sdim Result.push_back(ConstantExpr::get(Opcode, LHS, RHS)); 1149249259Sdim } 1150249259Sdim 1151249259Sdim return ConstantVector::get(Result); 1152249259Sdim } 1153249259Sdim 1154249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1155249259Sdim // There are many possible foldings we could do here. We should probably 1156249259Sdim // at least fold add of a pointer with an integer into the appropriate 1157249259Sdim // getelementptr. This will improve alias analysis a bit. 1158249259Sdim 1159249259Sdim // Given ((a + b) + c), if (b + c) folds to something interesting, return 1160249259Sdim // (a + (b + c)). 1161249259Sdim if (Instruction::isAssociative(Opcode) && CE1->getOpcode() == Opcode) { 1162249259Sdim Constant *T = ConstantExpr::get(Opcode, CE1->getOperand(1), C2); 1163249259Sdim if (!isa<ConstantExpr>(T) || cast<ConstantExpr>(T)->getOpcode() != Opcode) 1164249259Sdim return ConstantExpr::get(Opcode, CE1->getOperand(0), T); 1165249259Sdim } 1166249259Sdim } else if (isa<ConstantExpr>(C2)) { 1167249259Sdim // If C2 is a constant expr and C1 isn't, flop them around and fold the 1168249259Sdim // other way if possible. 1169249259Sdim if (Instruction::isCommutative(Opcode)) 1170249259Sdim return ConstantFoldBinaryInstruction(Opcode, C2, C1); 1171249259Sdim } 1172249259Sdim 1173249259Sdim // i1 can be simplified in many cases. 1174249259Sdim if (C1->getType()->isIntegerTy(1)) { 1175249259Sdim switch (Opcode) { 1176249259Sdim case Instruction::Add: 1177249259Sdim case Instruction::Sub: 1178249259Sdim return ConstantExpr::getXor(C1, C2); 1179249259Sdim case Instruction::Mul: 1180249259Sdim return ConstantExpr::getAnd(C1, C2); 1181249259Sdim case Instruction::Shl: 1182249259Sdim case Instruction::LShr: 1183249259Sdim case Instruction::AShr: 1184249259Sdim // We can assume that C2 == 0. If it were one the result would be 1185249259Sdim // undefined because the shift value is as large as the bitwidth. 1186249259Sdim return C1; 1187249259Sdim case Instruction::SDiv: 1188249259Sdim case Instruction::UDiv: 1189249259Sdim // We can assume that C2 == 1. If it were zero the result would be 1190249259Sdim // undefined through division by zero. 1191249259Sdim return C1; 1192249259Sdim case Instruction::URem: 1193249259Sdim case Instruction::SRem: 1194249259Sdim // We can assume that C2 == 1. If it were zero the result would be 1195249259Sdim // undefined through division by zero. 1196249259Sdim return ConstantInt::getFalse(C1->getContext()); 1197249259Sdim default: 1198249259Sdim break; 1199249259Sdim } 1200249259Sdim } 1201249259Sdim 1202249259Sdim // We don't know how to fold this. 1203249259Sdim return 0; 1204249259Sdim} 1205249259Sdim 1206249259Sdim/// isZeroSizedType - This type is zero sized if its an array or structure of 1207249259Sdim/// zero sized types. The only leaf zero sized type is an empty structure. 1208249259Sdimstatic bool isMaybeZeroSizedType(Type *Ty) { 1209249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) { 1210249259Sdim if (STy->isOpaque()) return true; // Can't say. 1211249259Sdim 1212249259Sdim // If all of elements have zero size, this does too. 1213249259Sdim for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) 1214249259Sdim if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; 1215249259Sdim return true; 1216249259Sdim 1217249259Sdim } else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 1218249259Sdim return isMaybeZeroSizedType(ATy->getElementType()); 1219249259Sdim } 1220249259Sdim return false; 1221249259Sdim} 1222249259Sdim 1223249259Sdim/// IdxCompare - Compare the two constants as though they were getelementptr 1224249259Sdim/// indices. This allows coersion of the types to be the same thing. 1225249259Sdim/// 1226249259Sdim/// If the two constants are the "same" (after coersion), return 0. If the 1227249259Sdim/// first is less than the second, return -1, if the second is less than the 1228249259Sdim/// first, return 1. If the constants are not integral, return -2. 1229249259Sdim/// 1230249259Sdimstatic int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) { 1231249259Sdim if (C1 == C2) return 0; 1232249259Sdim 1233249259Sdim // Ok, we found a different index. If they are not ConstantInt, we can't do 1234249259Sdim // anything with them. 1235249259Sdim if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) 1236249259Sdim return -2; // don't know! 1237249259Sdim 1238249259Sdim // Ok, we have two differing integer indices. Sign extend them to be the same 1239249259Sdim // type. Long is always big enough, so we use it. 1240249259Sdim if (!C1->getType()->isIntegerTy(64)) 1241249259Sdim C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(C1->getContext())); 1242249259Sdim 1243249259Sdim if (!C2->getType()->isIntegerTy(64)) 1244249259Sdim C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(C1->getContext())); 1245249259Sdim 1246249259Sdim if (C1 == C2) return 0; // They are equal 1247249259Sdim 1248249259Sdim // If the type being indexed over is really just a zero sized type, there is 1249249259Sdim // no pointer difference being made here. 1250249259Sdim if (isMaybeZeroSizedType(ElTy)) 1251249259Sdim return -2; // dunno. 1252249259Sdim 1253249259Sdim // If they are really different, now that they are the same type, then we 1254249259Sdim // found a difference! 1255249259Sdim if (cast<ConstantInt>(C1)->getSExtValue() < 1256249259Sdim cast<ConstantInt>(C2)->getSExtValue()) 1257249259Sdim return -1; 1258249259Sdim else 1259249259Sdim return 1; 1260249259Sdim} 1261249259Sdim 1262249259Sdim/// evaluateFCmpRelation - This function determines if there is anything we can 1263249259Sdim/// decide about the two constants provided. This doesn't need to handle simple 1264249259Sdim/// things like ConstantFP comparisons, but should instead handle ConstantExprs. 1265249259Sdim/// If we can determine that the two constants have a particular relation to 1266249259Sdim/// each other, we should return the corresponding FCmpInst predicate, 1267249259Sdim/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in 1268249259Sdim/// ConstantFoldCompareInstruction. 1269249259Sdim/// 1270249259Sdim/// To simplify this code we canonicalize the relation so that the first 1271249259Sdim/// operand is always the most "complex" of the two. We consider ConstantFP 1272249259Sdim/// to be the simplest, and ConstantExprs to be the most complex. 1273249259Sdimstatic FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) { 1274249259Sdim assert(V1->getType() == V2->getType() && 1275249259Sdim "Cannot compare values of different types!"); 1276249259Sdim 1277249259Sdim // Handle degenerate case quickly 1278249259Sdim if (V1 == V2) return FCmpInst::FCMP_OEQ; 1279249259Sdim 1280249259Sdim if (!isa<ConstantExpr>(V1)) { 1281249259Sdim if (!isa<ConstantExpr>(V2)) { 1282249259Sdim // We distilled thisUse the standard constant folder for a few cases 1283249259Sdim ConstantInt *R = 0; 1284249259Sdim R = dyn_cast<ConstantInt>( 1285249259Sdim ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2)); 1286249259Sdim if (R && !R->isZero()) 1287249259Sdim return FCmpInst::FCMP_OEQ; 1288249259Sdim R = dyn_cast<ConstantInt>( 1289249259Sdim ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2)); 1290249259Sdim if (R && !R->isZero()) 1291249259Sdim return FCmpInst::FCMP_OLT; 1292249259Sdim R = dyn_cast<ConstantInt>( 1293249259Sdim ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2)); 1294249259Sdim if (R && !R->isZero()) 1295249259Sdim return FCmpInst::FCMP_OGT; 1296249259Sdim 1297249259Sdim // Nothing more we can do 1298249259Sdim return FCmpInst::BAD_FCMP_PREDICATE; 1299249259Sdim } 1300249259Sdim 1301249259Sdim // If the first operand is simple and second is ConstantExpr, swap operands. 1302249259Sdim FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); 1303249259Sdim if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) 1304249259Sdim return FCmpInst::getSwappedPredicate(SwappedRelation); 1305249259Sdim } else { 1306249259Sdim // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1307249259Sdim // constantexpr or a simple constant. 1308249259Sdim ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1309249259Sdim switch (CE1->getOpcode()) { 1310249259Sdim case Instruction::FPTrunc: 1311249259Sdim case Instruction::FPExt: 1312249259Sdim case Instruction::UIToFP: 1313249259Sdim case Instruction::SIToFP: 1314249259Sdim // We might be able to do something with these but we don't right now. 1315249259Sdim break; 1316249259Sdim default: 1317249259Sdim break; 1318249259Sdim } 1319249259Sdim } 1320249259Sdim // There are MANY other foldings that we could perform here. They will 1321249259Sdim // probably be added on demand, as they seem needed. 1322249259Sdim return FCmpInst::BAD_FCMP_PREDICATE; 1323249259Sdim} 1324249259Sdim 1325249259Sdim/// evaluateICmpRelation - This function determines if there is anything we can 1326249259Sdim/// decide about the two constants provided. This doesn't need to handle simple 1327249259Sdim/// things like integer comparisons, but should instead handle ConstantExprs 1328249259Sdim/// and GlobalValues. If we can determine that the two constants have a 1329249259Sdim/// particular relation to each other, we should return the corresponding ICmp 1330249259Sdim/// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. 1331249259Sdim/// 1332249259Sdim/// To simplify this code we canonicalize the relation so that the first 1333249259Sdim/// operand is always the most "complex" of the two. We consider simple 1334249259Sdim/// constants (like ConstantInt) to be the simplest, followed by 1335249259Sdim/// GlobalValues, followed by ConstantExpr's (the most complex). 1336249259Sdim/// 1337249259Sdimstatic ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, 1338249259Sdim bool isSigned) { 1339249259Sdim assert(V1->getType() == V2->getType() && 1340249259Sdim "Cannot compare different types of values!"); 1341249259Sdim if (V1 == V2) return ICmpInst::ICMP_EQ; 1342249259Sdim 1343249259Sdim if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) && 1344249259Sdim !isa<BlockAddress>(V1)) { 1345249259Sdim if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) && 1346249259Sdim !isa<BlockAddress>(V2)) { 1347249259Sdim // We distilled this down to a simple case, use the standard constant 1348249259Sdim // folder. 1349249259Sdim ConstantInt *R = 0; 1350249259Sdim ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; 1351249259Sdim R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1352249259Sdim if (R && !R->isZero()) 1353249259Sdim return pred; 1354249259Sdim pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1355249259Sdim R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1356249259Sdim if (R && !R->isZero()) 1357249259Sdim return pred; 1358249259Sdim pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1359249259Sdim R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1360249259Sdim if (R && !R->isZero()) 1361249259Sdim return pred; 1362249259Sdim 1363249259Sdim // If we couldn't figure it out, bail. 1364249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1365249259Sdim } 1366249259Sdim 1367249259Sdim // If the first operand is simple, swap operands. 1368249259Sdim ICmpInst::Predicate SwappedRelation = 1369249259Sdim evaluateICmpRelation(V2, V1, isSigned); 1370249259Sdim if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1371249259Sdim return ICmpInst::getSwappedPredicate(SwappedRelation); 1372249259Sdim 1373249259Sdim } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) { 1374249259Sdim if (isa<ConstantExpr>(V2)) { // Swap as necessary. 1375249259Sdim ICmpInst::Predicate SwappedRelation = 1376249259Sdim evaluateICmpRelation(V2, V1, isSigned); 1377249259Sdim if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1378249259Sdim return ICmpInst::getSwappedPredicate(SwappedRelation); 1379249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1380249259Sdim } 1381249259Sdim 1382249259Sdim // Now we know that the RHS is a GlobalValue, BlockAddress or simple 1383249259Sdim // constant (which, since the types must match, means that it's a 1384249259Sdim // ConstantPointerNull). 1385249259Sdim if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { 1386249259Sdim // Don't try to decide equality of aliases. 1387249259Sdim if (!isa<GlobalAlias>(GV) && !isa<GlobalAlias>(GV2)) 1388249259Sdim if (!GV->hasExternalWeakLinkage() || !GV2->hasExternalWeakLinkage()) 1389249259Sdim return ICmpInst::ICMP_NE; 1390249259Sdim } else if (isa<BlockAddress>(V2)) { 1391249259Sdim return ICmpInst::ICMP_NE; // Globals never equal labels. 1392249259Sdim } else { 1393249259Sdim assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); 1394249259Sdim // GlobalVals can never be null unless they have external weak linkage. 1395249259Sdim // We don't try to evaluate aliases here. 1396249259Sdim if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV)) 1397249259Sdim return ICmpInst::ICMP_NE; 1398249259Sdim } 1399249259Sdim } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) { 1400249259Sdim if (isa<ConstantExpr>(V2)) { // Swap as necessary. 1401249259Sdim ICmpInst::Predicate SwappedRelation = 1402249259Sdim evaluateICmpRelation(V2, V1, isSigned); 1403249259Sdim if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1404249259Sdim return ICmpInst::getSwappedPredicate(SwappedRelation); 1405249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1406249259Sdim } 1407249259Sdim 1408249259Sdim // Now we know that the RHS is a GlobalValue, BlockAddress or simple 1409249259Sdim // constant (which, since the types must match, means that it is a 1410249259Sdim // ConstantPointerNull). 1411249259Sdim if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) { 1412249259Sdim // Block address in another function can't equal this one, but block 1413249259Sdim // addresses in the current function might be the same if blocks are 1414249259Sdim // empty. 1415249259Sdim if (BA2->getFunction() != BA->getFunction()) 1416249259Sdim return ICmpInst::ICMP_NE; 1417249259Sdim } else { 1418249259Sdim // Block addresses aren't null, don't equal the address of globals. 1419249259Sdim assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) && 1420249259Sdim "Canonicalization guarantee!"); 1421249259Sdim return ICmpInst::ICMP_NE; 1422249259Sdim } 1423249259Sdim } else { 1424249259Sdim // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1425249259Sdim // constantexpr, a global, block address, or a simple constant. 1426249259Sdim ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1427249259Sdim Constant *CE1Op0 = CE1->getOperand(0); 1428249259Sdim 1429249259Sdim switch (CE1->getOpcode()) { 1430249259Sdim case Instruction::Trunc: 1431249259Sdim case Instruction::FPTrunc: 1432249259Sdim case Instruction::FPExt: 1433249259Sdim case Instruction::FPToUI: 1434249259Sdim case Instruction::FPToSI: 1435249259Sdim break; // We can't evaluate floating point casts or truncations. 1436249259Sdim 1437249259Sdim case Instruction::UIToFP: 1438249259Sdim case Instruction::SIToFP: 1439249259Sdim case Instruction::BitCast: 1440249259Sdim case Instruction::ZExt: 1441249259Sdim case Instruction::SExt: 1442249259Sdim // If the cast is not actually changing bits, and the second operand is a 1443249259Sdim // null pointer, do the comparison with the pre-casted value. 1444249259Sdim if (V2->isNullValue() && 1445249259Sdim (CE1->getType()->isPointerTy() || CE1->getType()->isIntegerTy())) { 1446249259Sdim if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 1447249259Sdim if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 1448249259Sdim return evaluateICmpRelation(CE1Op0, 1449249259Sdim Constant::getNullValue(CE1Op0->getType()), 1450249259Sdim isSigned); 1451249259Sdim } 1452249259Sdim break; 1453249259Sdim 1454249259Sdim case Instruction::GetElementPtr: 1455249259Sdim // Ok, since this is a getelementptr, we know that the constant has a 1456249259Sdim // pointer type. Check the various cases. 1457249259Sdim if (isa<ConstantPointerNull>(V2)) { 1458249259Sdim // If we are comparing a GEP to a null pointer, check to see if the base 1459249259Sdim // of the GEP equals the null pointer. 1460249259Sdim if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1461249259Sdim if (GV->hasExternalWeakLinkage()) 1462249259Sdim // Weak linkage GVals could be zero or not. We're comparing that 1463249259Sdim // to null pointer so its greater-or-equal 1464249259Sdim return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; 1465249259Sdim else 1466249259Sdim // If its not weak linkage, the GVal must have a non-zero address 1467249259Sdim // so the result is greater-than 1468249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1469249259Sdim } else if (isa<ConstantPointerNull>(CE1Op0)) { 1470249259Sdim // If we are indexing from a null pointer, check to see if we have any 1471249259Sdim // non-zero indices. 1472249259Sdim for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) 1473249259Sdim if (!CE1->getOperand(i)->isNullValue()) 1474249259Sdim // Offsetting from null, must not be equal. 1475249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1476249259Sdim // Only zero indexes from null, must still be zero. 1477249259Sdim return ICmpInst::ICMP_EQ; 1478249259Sdim } 1479249259Sdim // Otherwise, we can't really say if the first operand is null or not. 1480249259Sdim } else if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { 1481249259Sdim if (isa<ConstantPointerNull>(CE1Op0)) { 1482249259Sdim if (GV2->hasExternalWeakLinkage()) 1483249259Sdim // Weak linkage GVals could be zero or not. We're comparing it to 1484249259Sdim // a null pointer, so its less-or-equal 1485249259Sdim return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; 1486249259Sdim else 1487249259Sdim // If its not weak linkage, the GVal must have a non-zero address 1488249259Sdim // so the result is less-than 1489249259Sdim return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1490249259Sdim } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1491249259Sdim if (GV == GV2) { 1492249259Sdim // If this is a getelementptr of the same global, then it must be 1493249259Sdim // different. Because the types must match, the getelementptr could 1494249259Sdim // only have at most one index, and because we fold getelementptr's 1495249259Sdim // with a single zero index, it must be nonzero. 1496249259Sdim assert(CE1->getNumOperands() == 2 && 1497249259Sdim !CE1->getOperand(1)->isNullValue() && 1498249259Sdim "Surprising getelementptr!"); 1499249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1500249259Sdim } else { 1501249259Sdim // If they are different globals, we don't know what the value is. 1502249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1503249259Sdim } 1504249259Sdim } 1505249259Sdim } else { 1506249259Sdim ConstantExpr *CE2 = cast<ConstantExpr>(V2); 1507249259Sdim Constant *CE2Op0 = CE2->getOperand(0); 1508249259Sdim 1509249259Sdim // There are MANY other foldings that we could perform here. They will 1510249259Sdim // probably be added on demand, as they seem needed. 1511249259Sdim switch (CE2->getOpcode()) { 1512249259Sdim default: break; 1513249259Sdim case Instruction::GetElementPtr: 1514249259Sdim // By far the most common case to handle is when the base pointers are 1515249259Sdim // obviously to the same global. 1516249259Sdim if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { 1517249259Sdim if (CE1Op0 != CE2Op0) // Don't know relative ordering. 1518249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1519249259Sdim // Ok, we know that both getelementptr instructions are based on the 1520249259Sdim // same global. From this, we can precisely determine the relative 1521249259Sdim // ordering of the resultant pointers. 1522249259Sdim unsigned i = 1; 1523249259Sdim 1524249259Sdim // The logic below assumes that the result of the comparison 1525249259Sdim // can be determined by finding the first index that differs. 1526249259Sdim // This doesn't work if there is over-indexing in any 1527249259Sdim // subsequent indices, so check for that case first. 1528249259Sdim if (!CE1->isGEPWithNoNotionalOverIndexing() || 1529249259Sdim !CE2->isGEPWithNoNotionalOverIndexing()) 1530249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1531249259Sdim 1532249259Sdim // Compare all of the operands the GEP's have in common. 1533249259Sdim gep_type_iterator GTI = gep_type_begin(CE1); 1534249259Sdim for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); 1535249259Sdim ++i, ++GTI) 1536249259Sdim switch (IdxCompare(CE1->getOperand(i), 1537249259Sdim CE2->getOperand(i), GTI.getIndexedType())) { 1538249259Sdim case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; 1539249259Sdim case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; 1540249259Sdim case -2: return ICmpInst::BAD_ICMP_PREDICATE; 1541249259Sdim } 1542249259Sdim 1543249259Sdim // Ok, we ran out of things they have in common. If any leftovers 1544249259Sdim // are non-zero then we have a difference, otherwise we are equal. 1545249259Sdim for (; i < CE1->getNumOperands(); ++i) 1546249259Sdim if (!CE1->getOperand(i)->isNullValue()) { 1547249259Sdim if (isa<ConstantInt>(CE1->getOperand(i))) 1548249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1549249259Sdim else 1550249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1551249259Sdim } 1552249259Sdim 1553249259Sdim for (; i < CE2->getNumOperands(); ++i) 1554249259Sdim if (!CE2->getOperand(i)->isNullValue()) { 1555249259Sdim if (isa<ConstantInt>(CE2->getOperand(i))) 1556249259Sdim return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1557249259Sdim else 1558249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1559249259Sdim } 1560249259Sdim return ICmpInst::ICMP_EQ; 1561249259Sdim } 1562249259Sdim } 1563249259Sdim } 1564249259Sdim default: 1565249259Sdim break; 1566249259Sdim } 1567249259Sdim } 1568249259Sdim 1569249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1570249259Sdim} 1571249259Sdim 1572249259SdimConstant *llvm::ConstantFoldCompareInstruction(unsigned short pred, 1573249259Sdim Constant *C1, Constant *C2) { 1574249259Sdim Type *ResultTy; 1575249259Sdim if (VectorType *VT = dyn_cast<VectorType>(C1->getType())) 1576249259Sdim ResultTy = VectorType::get(Type::getInt1Ty(C1->getContext()), 1577249259Sdim VT->getNumElements()); 1578249259Sdim else 1579249259Sdim ResultTy = Type::getInt1Ty(C1->getContext()); 1580249259Sdim 1581249259Sdim // Fold FCMP_FALSE/FCMP_TRUE unconditionally. 1582249259Sdim if (pred == FCmpInst::FCMP_FALSE) 1583249259Sdim return Constant::getNullValue(ResultTy); 1584249259Sdim 1585249259Sdim if (pred == FCmpInst::FCMP_TRUE) 1586249259Sdim return Constant::getAllOnesValue(ResultTy); 1587249259Sdim 1588249259Sdim // Handle some degenerate cases first 1589249259Sdim if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 1590249259Sdim // For EQ and NE, we can always pick a value for the undef to make the 1591249259Sdim // predicate pass or fail, so we can return undef. 1592249259Sdim // Also, if both operands are undef, we can return undef. 1593249259Sdim if (ICmpInst::isEquality(ICmpInst::Predicate(pred)) || 1594249259Sdim (isa<UndefValue>(C1) && isa<UndefValue>(C2))) 1595249259Sdim return UndefValue::get(ResultTy); 1596249259Sdim // Otherwise, pick the same value as the non-undef operand, and fold 1597249259Sdim // it to true or false. 1598249259Sdim return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(pred)); 1599249259Sdim } 1600249259Sdim 1601249259Sdim // icmp eq/ne(null,GV) -> false/true 1602249259Sdim if (C1->isNullValue()) { 1603249259Sdim if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) 1604249259Sdim // Don't try to evaluate aliases. External weak GV can be null. 1605249259Sdim if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1606249259Sdim if (pred == ICmpInst::ICMP_EQ) 1607249259Sdim return ConstantInt::getFalse(C1->getContext()); 1608249259Sdim else if (pred == ICmpInst::ICMP_NE) 1609249259Sdim return ConstantInt::getTrue(C1->getContext()); 1610249259Sdim } 1611249259Sdim // icmp eq/ne(GV,null) -> false/true 1612249259Sdim } else if (C2->isNullValue()) { 1613249259Sdim if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) 1614249259Sdim // Don't try to evaluate aliases. External weak GV can be null. 1615249259Sdim if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1616249259Sdim if (pred == ICmpInst::ICMP_EQ) 1617249259Sdim return ConstantInt::getFalse(C1->getContext()); 1618249259Sdim else if (pred == ICmpInst::ICMP_NE) 1619249259Sdim return ConstantInt::getTrue(C1->getContext()); 1620249259Sdim } 1621249259Sdim } 1622249259Sdim 1623249259Sdim // If the comparison is a comparison between two i1's, simplify it. 1624249259Sdim if (C1->getType()->isIntegerTy(1)) { 1625249259Sdim switch(pred) { 1626249259Sdim case ICmpInst::ICMP_EQ: 1627249259Sdim if (isa<ConstantInt>(C2)) 1628249259Sdim return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2)); 1629249259Sdim return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2); 1630249259Sdim case ICmpInst::ICMP_NE: 1631249259Sdim return ConstantExpr::getXor(C1, C2); 1632249259Sdim default: 1633249259Sdim break; 1634249259Sdim } 1635249259Sdim } 1636249259Sdim 1637249259Sdim if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { 1638249259Sdim APInt V1 = cast<ConstantInt>(C1)->getValue(); 1639249259Sdim APInt V2 = cast<ConstantInt>(C2)->getValue(); 1640249259Sdim switch (pred) { 1641249259Sdim default: llvm_unreachable("Invalid ICmp Predicate"); 1642249259Sdim case ICmpInst::ICMP_EQ: return ConstantInt::get(ResultTy, V1 == V2); 1643249259Sdim case ICmpInst::ICMP_NE: return ConstantInt::get(ResultTy, V1 != V2); 1644249259Sdim case ICmpInst::ICMP_SLT: return ConstantInt::get(ResultTy, V1.slt(V2)); 1645249259Sdim case ICmpInst::ICMP_SGT: return ConstantInt::get(ResultTy, V1.sgt(V2)); 1646249259Sdim case ICmpInst::ICMP_SLE: return ConstantInt::get(ResultTy, V1.sle(V2)); 1647249259Sdim case ICmpInst::ICMP_SGE: return ConstantInt::get(ResultTy, V1.sge(V2)); 1648249259Sdim case ICmpInst::ICMP_ULT: return ConstantInt::get(ResultTy, V1.ult(V2)); 1649249259Sdim case ICmpInst::ICMP_UGT: return ConstantInt::get(ResultTy, V1.ugt(V2)); 1650249259Sdim case ICmpInst::ICMP_ULE: return ConstantInt::get(ResultTy, V1.ule(V2)); 1651249259Sdim case ICmpInst::ICMP_UGE: return ConstantInt::get(ResultTy, V1.uge(V2)); 1652249259Sdim } 1653249259Sdim } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { 1654249259Sdim APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); 1655249259Sdim APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); 1656249259Sdim APFloat::cmpResult R = C1V.compare(C2V); 1657249259Sdim switch (pred) { 1658249259Sdim default: llvm_unreachable("Invalid FCmp Predicate"); 1659249259Sdim case FCmpInst::FCMP_FALSE: return Constant::getNullValue(ResultTy); 1660249259Sdim case FCmpInst::FCMP_TRUE: return Constant::getAllOnesValue(ResultTy); 1661249259Sdim case FCmpInst::FCMP_UNO: 1662249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered); 1663249259Sdim case FCmpInst::FCMP_ORD: 1664249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpUnordered); 1665249259Sdim case FCmpInst::FCMP_UEQ: 1666249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1667249259Sdim R==APFloat::cmpEqual); 1668249259Sdim case FCmpInst::FCMP_OEQ: 1669249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpEqual); 1670249259Sdim case FCmpInst::FCMP_UNE: 1671249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpEqual); 1672249259Sdim case FCmpInst::FCMP_ONE: 1673249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || 1674249259Sdim R==APFloat::cmpGreaterThan); 1675249259Sdim case FCmpInst::FCMP_ULT: 1676249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1677249259Sdim R==APFloat::cmpLessThan); 1678249259Sdim case FCmpInst::FCMP_OLT: 1679249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan); 1680249259Sdim case FCmpInst::FCMP_UGT: 1681249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1682249259Sdim R==APFloat::cmpGreaterThan); 1683249259Sdim case FCmpInst::FCMP_OGT: 1684249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan); 1685249259Sdim case FCmpInst::FCMP_ULE: 1686249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpGreaterThan); 1687249259Sdim case FCmpInst::FCMP_OLE: 1688249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || 1689249259Sdim R==APFloat::cmpEqual); 1690249259Sdim case FCmpInst::FCMP_UGE: 1691249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpLessThan); 1692249259Sdim case FCmpInst::FCMP_OGE: 1693249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan || 1694249259Sdim R==APFloat::cmpEqual); 1695249259Sdim } 1696249259Sdim } else if (C1->getType()->isVectorTy()) { 1697249259Sdim // If we can constant fold the comparison of each element, constant fold 1698249259Sdim // the whole vector comparison. 1699249259Sdim SmallVector<Constant*, 4> ResElts; 1700249259Sdim Type *Ty = IntegerType::get(C1->getContext(), 32); 1701249259Sdim // Compare the elements, producing an i1 result or constant expr. 1702249259Sdim for (unsigned i = 0, e = C1->getType()->getVectorNumElements(); i != e;++i){ 1703249259Sdim Constant *C1E = 1704249259Sdim ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, i)); 1705249259Sdim Constant *C2E = 1706249259Sdim ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, i)); 1707249259Sdim 1708249259Sdim ResElts.push_back(ConstantExpr::getCompare(pred, C1E, C2E)); 1709249259Sdim } 1710249259Sdim 1711249259Sdim return ConstantVector::get(ResElts); 1712249259Sdim } 1713249259Sdim 1714249259Sdim if (C1->getType()->isFloatingPointTy()) { 1715249259Sdim int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1716249259Sdim switch (evaluateFCmpRelation(C1, C2)) { 1717249259Sdim default: llvm_unreachable("Unknown relation!"); 1718249259Sdim case FCmpInst::FCMP_UNO: 1719249259Sdim case FCmpInst::FCMP_ORD: 1720249259Sdim case FCmpInst::FCMP_UEQ: 1721249259Sdim case FCmpInst::FCMP_UNE: 1722249259Sdim case FCmpInst::FCMP_ULT: 1723249259Sdim case FCmpInst::FCMP_UGT: 1724249259Sdim case FCmpInst::FCMP_ULE: 1725249259Sdim case FCmpInst::FCMP_UGE: 1726249259Sdim case FCmpInst::FCMP_TRUE: 1727249259Sdim case FCmpInst::FCMP_FALSE: 1728249259Sdim case FCmpInst::BAD_FCMP_PREDICATE: 1729249259Sdim break; // Couldn't determine anything about these constants. 1730249259Sdim case FCmpInst::FCMP_OEQ: // We know that C1 == C2 1731249259Sdim Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || 1732249259Sdim pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || 1733249259Sdim pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1734249259Sdim break; 1735249259Sdim case FCmpInst::FCMP_OLT: // We know that C1 < C2 1736249259Sdim Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1737249259Sdim pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || 1738249259Sdim pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); 1739249259Sdim break; 1740249259Sdim case FCmpInst::FCMP_OGT: // We know that C1 > C2 1741249259Sdim Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1742249259Sdim pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || 1743249259Sdim pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1744249259Sdim break; 1745249259Sdim case FCmpInst::FCMP_OLE: // We know that C1 <= C2 1746249259Sdim // We can only partially decide this relation. 1747249259Sdim if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1748249259Sdim Result = 0; 1749249259Sdim else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1750249259Sdim Result = 1; 1751249259Sdim break; 1752249259Sdim case FCmpInst::FCMP_OGE: // We known that C1 >= C2 1753249259Sdim // We can only partially decide this relation. 1754249259Sdim if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1755249259Sdim Result = 0; 1756249259Sdim else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1757249259Sdim Result = 1; 1758249259Sdim break; 1759249259Sdim case FCmpInst::FCMP_ONE: // We know that C1 != C2 1760249259Sdim // We can only partially decide this relation. 1761249259Sdim if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) 1762249259Sdim Result = 0; 1763249259Sdim else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) 1764249259Sdim Result = 1; 1765249259Sdim break; 1766249259Sdim } 1767249259Sdim 1768249259Sdim // If we evaluated the result, return it now. 1769249259Sdim if (Result != -1) 1770249259Sdim return ConstantInt::get(ResultTy, Result); 1771249259Sdim 1772249259Sdim } else { 1773249259Sdim // Evaluate the relation between the two constants, per the predicate. 1774249259Sdim int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1775249259Sdim switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) { 1776249259Sdim default: llvm_unreachable("Unknown relational!"); 1777249259Sdim case ICmpInst::BAD_ICMP_PREDICATE: 1778249259Sdim break; // Couldn't determine anything about these constants. 1779249259Sdim case ICmpInst::ICMP_EQ: // We know the constants are equal! 1780249259Sdim // If we know the constants are equal, we can decide the result of this 1781249259Sdim // computation precisely. 1782249259Sdim Result = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred); 1783249259Sdim break; 1784249259Sdim case ICmpInst::ICMP_ULT: 1785249259Sdim switch (pred) { 1786249259Sdim case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE: 1787249259Sdim Result = 1; break; 1788249259Sdim case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE: 1789249259Sdim Result = 0; break; 1790249259Sdim } 1791249259Sdim break; 1792249259Sdim case ICmpInst::ICMP_SLT: 1793249259Sdim switch (pred) { 1794249259Sdim case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE: 1795249259Sdim Result = 1; break; 1796249259Sdim case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE: 1797249259Sdim Result = 0; break; 1798249259Sdim } 1799249259Sdim break; 1800249259Sdim case ICmpInst::ICMP_UGT: 1801249259Sdim switch (pred) { 1802249259Sdim case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE: 1803249259Sdim Result = 1; break; 1804249259Sdim case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE: 1805249259Sdim Result = 0; break; 1806249259Sdim } 1807249259Sdim break; 1808249259Sdim case ICmpInst::ICMP_SGT: 1809249259Sdim switch (pred) { 1810249259Sdim case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE: 1811249259Sdim Result = 1; break; 1812249259Sdim case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE: 1813249259Sdim Result = 0; break; 1814249259Sdim } 1815249259Sdim break; 1816249259Sdim case ICmpInst::ICMP_ULE: 1817249259Sdim if (pred == ICmpInst::ICMP_UGT) Result = 0; 1818249259Sdim if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1; 1819249259Sdim break; 1820249259Sdim case ICmpInst::ICMP_SLE: 1821249259Sdim if (pred == ICmpInst::ICMP_SGT) Result = 0; 1822249259Sdim if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1; 1823249259Sdim break; 1824249259Sdim case ICmpInst::ICMP_UGE: 1825249259Sdim if (pred == ICmpInst::ICMP_ULT) Result = 0; 1826249259Sdim if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1; 1827249259Sdim break; 1828249259Sdim case ICmpInst::ICMP_SGE: 1829249259Sdim if (pred == ICmpInst::ICMP_SLT) Result = 0; 1830249259Sdim if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1; 1831249259Sdim break; 1832249259Sdim case ICmpInst::ICMP_NE: 1833249259Sdim if (pred == ICmpInst::ICMP_EQ) Result = 0; 1834249259Sdim if (pred == ICmpInst::ICMP_NE) Result = 1; 1835249259Sdim break; 1836249259Sdim } 1837249259Sdim 1838249259Sdim // If we evaluated the result, return it now. 1839249259Sdim if (Result != -1) 1840249259Sdim return ConstantInt::get(ResultTy, Result); 1841249259Sdim 1842249259Sdim // If the right hand side is a bitcast, try using its inverse to simplify 1843249259Sdim // it by moving it to the left hand side. We can't do this if it would turn 1844249259Sdim // a vector compare into a scalar compare or visa versa. 1845249259Sdim if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) { 1846249259Sdim Constant *CE2Op0 = CE2->getOperand(0); 1847249259Sdim if (CE2->getOpcode() == Instruction::BitCast && 1848249259Sdim CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy()) { 1849249259Sdim Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType()); 1850249259Sdim return ConstantExpr::getICmp(pred, Inverse, CE2Op0); 1851249259Sdim } 1852249259Sdim } 1853249259Sdim 1854249259Sdim // If the left hand side is an extension, try eliminating it. 1855249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1856249259Sdim if ((CE1->getOpcode() == Instruction::SExt && ICmpInst::isSigned(pred)) || 1857249259Sdim (CE1->getOpcode() == Instruction::ZExt && !ICmpInst::isSigned(pred))){ 1858249259Sdim Constant *CE1Op0 = CE1->getOperand(0); 1859249259Sdim Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType()); 1860249259Sdim if (CE1Inverse == CE1Op0) { 1861249259Sdim // Check whether we can safely truncate the right hand side. 1862249259Sdim Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType()); 1863263508Sdim if (ConstantExpr::getCast(CE1->getOpcode(), C2Inverse, 1864263508Sdim C2->getType()) == C2) 1865249259Sdim return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse); 1866249259Sdim } 1867249259Sdim } 1868249259Sdim } 1869249259Sdim 1870249259Sdim if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) || 1871249259Sdim (C1->isNullValue() && !C2->isNullValue())) { 1872249259Sdim // If C2 is a constant expr and C1 isn't, flip them around and fold the 1873249259Sdim // other way if possible. 1874249259Sdim // Also, if C1 is null and C2 isn't, flip them around. 1875249259Sdim pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); 1876249259Sdim return ConstantExpr::getICmp(pred, C2, C1); 1877249259Sdim } 1878249259Sdim } 1879249259Sdim return 0; 1880249259Sdim} 1881249259Sdim 1882249259Sdim/// isInBoundsIndices - Test whether the given sequence of *normalized* indices 1883249259Sdim/// is "inbounds". 1884249259Sdimtemplate<typename IndexTy> 1885249259Sdimstatic bool isInBoundsIndices(ArrayRef<IndexTy> Idxs) { 1886249259Sdim // No indices means nothing that could be out of bounds. 1887249259Sdim if (Idxs.empty()) return true; 1888249259Sdim 1889249259Sdim // If the first index is zero, it's in bounds. 1890249259Sdim if (cast<Constant>(Idxs[0])->isNullValue()) return true; 1891249259Sdim 1892249259Sdim // If the first index is one and all the rest are zero, it's in bounds, 1893249259Sdim // by the one-past-the-end rule. 1894249259Sdim if (!cast<ConstantInt>(Idxs[0])->isOne()) 1895249259Sdim return false; 1896249259Sdim for (unsigned i = 1, e = Idxs.size(); i != e; ++i) 1897249259Sdim if (!cast<Constant>(Idxs[i])->isNullValue()) 1898249259Sdim return false; 1899249259Sdim return true; 1900249259Sdim} 1901249259Sdim 1902263508Sdim/// \brief Test whether a given ConstantInt is in-range for a SequentialType. 1903263508Sdimstatic bool isIndexInRangeOfSequentialType(const SequentialType *STy, 1904263508Sdim const ConstantInt *CI) { 1905263508Sdim if (const PointerType *PTy = dyn_cast<PointerType>(STy)) 1906263508Sdim // Only handle pointers to sized types, not pointers to functions. 1907263508Sdim return PTy->getElementType()->isSized(); 1908263508Sdim 1909263508Sdim uint64_t NumElements = 0; 1910263508Sdim // Determine the number of elements in our sequential type. 1911263508Sdim if (const ArrayType *ATy = dyn_cast<ArrayType>(STy)) 1912263508Sdim NumElements = ATy->getNumElements(); 1913263508Sdim else if (const VectorType *VTy = dyn_cast<VectorType>(STy)) 1914263508Sdim NumElements = VTy->getNumElements(); 1915263508Sdim 1916263508Sdim assert((isa<ArrayType>(STy) || NumElements > 0) && 1917263508Sdim "didn't expect non-array type to have zero elements!"); 1918263508Sdim 1919263508Sdim // We cannot bounds check the index if it doesn't fit in an int64_t. 1920263508Sdim if (CI->getValue().getActiveBits() > 64) 1921263508Sdim return false; 1922263508Sdim 1923263508Sdim // A negative index or an index past the end of our sequential type is 1924263508Sdim // considered out-of-range. 1925263508Sdim int64_t IndexVal = CI->getSExtValue(); 1926263508Sdim if (IndexVal < 0 || (NumElements > 0 && (uint64_t)IndexVal >= NumElements)) 1927263508Sdim return false; 1928263508Sdim 1929263508Sdim // Otherwise, it is in-range. 1930263508Sdim return true; 1931263508Sdim} 1932263508Sdim 1933249259Sdimtemplate<typename IndexTy> 1934249259Sdimstatic Constant *ConstantFoldGetElementPtrImpl(Constant *C, 1935249259Sdim bool inBounds, 1936249259Sdim ArrayRef<IndexTy> Idxs) { 1937249259Sdim if (Idxs.empty()) return C; 1938249259Sdim Constant *Idx0 = cast<Constant>(Idxs[0]); 1939249259Sdim if ((Idxs.size() == 1 && Idx0->isNullValue())) 1940249259Sdim return C; 1941249259Sdim 1942249259Sdim if (isa<UndefValue>(C)) { 1943249259Sdim PointerType *Ptr = cast<PointerType>(C->getType()); 1944249259Sdim Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs); 1945249259Sdim assert(Ty != 0 && "Invalid indices for GEP!"); 1946249259Sdim return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); 1947249259Sdim } 1948249259Sdim 1949249259Sdim if (C->isNullValue()) { 1950249259Sdim bool isNull = true; 1951249259Sdim for (unsigned i = 0, e = Idxs.size(); i != e; ++i) 1952249259Sdim if (!cast<Constant>(Idxs[i])->isNullValue()) { 1953249259Sdim isNull = false; 1954249259Sdim break; 1955249259Sdim } 1956249259Sdim if (isNull) { 1957249259Sdim PointerType *Ptr = cast<PointerType>(C->getType()); 1958249259Sdim Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs); 1959249259Sdim assert(Ty != 0 && "Invalid indices for GEP!"); 1960249259Sdim return ConstantPointerNull::get(PointerType::get(Ty, 1961249259Sdim Ptr->getAddressSpace())); 1962249259Sdim } 1963249259Sdim } 1964249259Sdim 1965249259Sdim if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { 1966249259Sdim // Combine Indices - If the source pointer to this getelementptr instruction 1967249259Sdim // is a getelementptr instruction, combine the indices of the two 1968249259Sdim // getelementptr instructions into a single instruction. 1969249259Sdim // 1970249259Sdim if (CE->getOpcode() == Instruction::GetElementPtr) { 1971249259Sdim Type *LastTy = 0; 1972249259Sdim for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); 1973249259Sdim I != E; ++I) 1974249259Sdim LastTy = *I; 1975249259Sdim 1976263508Sdim // We cannot combine indices if doing so would take us outside of an 1977263508Sdim // array or vector. Doing otherwise could trick us if we evaluated such a 1978263508Sdim // GEP as part of a load. 1979263508Sdim // 1980263508Sdim // e.g. Consider if the original GEP was: 1981263508Sdim // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c, 1982263508Sdim // i32 0, i32 0, i64 0) 1983263508Sdim // 1984263508Sdim // If we then tried to offset it by '8' to get to the third element, 1985263508Sdim // an i8, we should *not* get: 1986263508Sdim // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c, 1987263508Sdim // i32 0, i32 0, i64 8) 1988263508Sdim // 1989263508Sdim // This GEP tries to index array element '8 which runs out-of-bounds. 1990263508Sdim // Subsequent evaluation would get confused and produce erroneous results. 1991263508Sdim // 1992263508Sdim // The following prohibits such a GEP from being formed by checking to see 1993263508Sdim // if the index is in-range with respect to an array or vector. 1994263508Sdim bool PerformFold = false; 1995263508Sdim if (Idx0->isNullValue()) 1996263508Sdim PerformFold = true; 1997263508Sdim else if (SequentialType *STy = dyn_cast_or_null<SequentialType>(LastTy)) 1998263508Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx0)) 1999263508Sdim PerformFold = isIndexInRangeOfSequentialType(STy, CI); 2000263508Sdim 2001263508Sdim if (PerformFold) { 2002249259Sdim SmallVector<Value*, 16> NewIndices; 2003249259Sdim NewIndices.reserve(Idxs.size() + CE->getNumOperands()); 2004249259Sdim for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) 2005249259Sdim NewIndices.push_back(CE->getOperand(i)); 2006249259Sdim 2007249259Sdim // Add the last index of the source with the first index of the new GEP. 2008249259Sdim // Make sure to handle the case when they are actually different types. 2009249259Sdim Constant *Combined = CE->getOperand(CE->getNumOperands()-1); 2010249259Sdim // Otherwise it must be an array. 2011249259Sdim if (!Idx0->isNullValue()) { 2012249259Sdim Type *IdxTy = Combined->getType(); 2013249259Sdim if (IdxTy != Idx0->getType()) { 2014249259Sdim Type *Int64Ty = Type::getInt64Ty(IdxTy->getContext()); 2015249259Sdim Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Int64Ty); 2016249259Sdim Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, Int64Ty); 2017249259Sdim Combined = ConstantExpr::get(Instruction::Add, C1, C2); 2018249259Sdim } else { 2019249259Sdim Combined = 2020249259Sdim ConstantExpr::get(Instruction::Add, Idx0, Combined); 2021249259Sdim } 2022249259Sdim } 2023249259Sdim 2024249259Sdim NewIndices.push_back(Combined); 2025249259Sdim NewIndices.append(Idxs.begin() + 1, Idxs.end()); 2026249259Sdim return 2027249259Sdim ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices, 2028249259Sdim inBounds && 2029249259Sdim cast<GEPOperator>(CE)->isInBounds()); 2030249259Sdim } 2031249259Sdim } 2032249259Sdim 2033249259Sdim // Attempt to fold casts to the same type away. For example, folding: 2034249259Sdim // 2035249259Sdim // i32* getelementptr ([2 x i32]* bitcast ([3 x i32]* %X to [2 x i32]*), 2036249259Sdim // i64 0, i64 0) 2037249259Sdim // into: 2038249259Sdim // 2039249259Sdim // i32* getelementptr ([3 x i32]* %X, i64 0, i64 0) 2040249259Sdim // 2041249259Sdim // Don't fold if the cast is changing address spaces. 2042249259Sdim if (CE->isCast() && Idxs.size() > 1 && Idx0->isNullValue()) { 2043249259Sdim PointerType *SrcPtrTy = 2044249259Sdim dyn_cast<PointerType>(CE->getOperand(0)->getType()); 2045249259Sdim PointerType *DstPtrTy = dyn_cast<PointerType>(CE->getType()); 2046249259Sdim if (SrcPtrTy && DstPtrTy) { 2047249259Sdim ArrayType *SrcArrayTy = 2048249259Sdim dyn_cast<ArrayType>(SrcPtrTy->getElementType()); 2049249259Sdim ArrayType *DstArrayTy = 2050249259Sdim dyn_cast<ArrayType>(DstPtrTy->getElementType()); 2051249259Sdim if (SrcArrayTy && DstArrayTy 2052249259Sdim && SrcArrayTy->getElementType() == DstArrayTy->getElementType() 2053249259Sdim && SrcPtrTy->getAddressSpace() == DstPtrTy->getAddressSpace()) 2054249259Sdim return ConstantExpr::getGetElementPtr((Constant*)CE->getOperand(0), 2055249259Sdim Idxs, inBounds); 2056249259Sdim } 2057249259Sdim } 2058249259Sdim } 2059249259Sdim 2060249259Sdim // Check to see if any array indices are not within the corresponding 2061263508Sdim // notional array or vector bounds. If so, try to determine if they can be 2062263508Sdim // factored out into preceding dimensions. 2063249259Sdim bool Unknown = false; 2064249259Sdim SmallVector<Constant *, 8> NewIdxs; 2065249259Sdim Type *Ty = C->getType(); 2066249259Sdim Type *Prev = 0; 2067249259Sdim for (unsigned i = 0, e = Idxs.size(); i != e; 2068249259Sdim Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) { 2069249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) { 2070263508Sdim if (isa<ArrayType>(Ty) || isa<VectorType>(Ty)) 2071263508Sdim if (CI->getSExtValue() > 0 && 2072263508Sdim !isIndexInRangeOfSequentialType(cast<SequentialType>(Ty), CI)) { 2073249259Sdim if (isa<SequentialType>(Prev)) { 2074249259Sdim // It's out of range, but we can factor it into the prior 2075249259Sdim // dimension. 2076249259Sdim NewIdxs.resize(Idxs.size()); 2077263508Sdim uint64_t NumElements = 0; 2078263508Sdim if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) 2079263508Sdim NumElements = ATy->getNumElements(); 2080263508Sdim else 2081263508Sdim NumElements = cast<VectorType>(Ty)->getNumElements(); 2082263508Sdim 2083263508Sdim ConstantInt *Factor = ConstantInt::get(CI->getType(), NumElements); 2084249259Sdim NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); 2085249259Sdim 2086249259Sdim Constant *PrevIdx = cast<Constant>(Idxs[i-1]); 2087249259Sdim Constant *Div = ConstantExpr::getSDiv(CI, Factor); 2088249259Sdim 2089249259Sdim // Before adding, extend both operands to i64 to avoid 2090249259Sdim // overflow trouble. 2091249259Sdim if (!PrevIdx->getType()->isIntegerTy(64)) 2092249259Sdim PrevIdx = ConstantExpr::getSExt(PrevIdx, 2093249259Sdim Type::getInt64Ty(Div->getContext())); 2094249259Sdim if (!Div->getType()->isIntegerTy(64)) 2095249259Sdim Div = ConstantExpr::getSExt(Div, 2096249259Sdim Type::getInt64Ty(Div->getContext())); 2097249259Sdim 2098249259Sdim NewIdxs[i-1] = ConstantExpr::getAdd(PrevIdx, Div); 2099249259Sdim } else { 2100249259Sdim // It's out of range, but the prior dimension is a struct 2101249259Sdim // so we can't do anything about it. 2102249259Sdim Unknown = true; 2103249259Sdim } 2104249259Sdim } 2105249259Sdim } else { 2106249259Sdim // We don't know if it's in range or not. 2107249259Sdim Unknown = true; 2108249259Sdim } 2109249259Sdim } 2110249259Sdim 2111249259Sdim // If we did any factoring, start over with the adjusted indices. 2112249259Sdim if (!NewIdxs.empty()) { 2113249259Sdim for (unsigned i = 0, e = Idxs.size(); i != e; ++i) 2114249259Sdim if (!NewIdxs[i]) NewIdxs[i] = cast<Constant>(Idxs[i]); 2115249259Sdim return ConstantExpr::getGetElementPtr(C, NewIdxs, inBounds); 2116249259Sdim } 2117249259Sdim 2118249259Sdim // If all indices are known integers and normalized, we can do a simple 2119249259Sdim // check for the "inbounds" property. 2120249259Sdim if (!Unknown && !inBounds && 2121249259Sdim isa<GlobalVariable>(C) && isInBoundsIndices(Idxs)) 2122249259Sdim return ConstantExpr::getInBoundsGetElementPtr(C, Idxs); 2123249259Sdim 2124249259Sdim return 0; 2125249259Sdim} 2126249259Sdim 2127249259SdimConstant *llvm::ConstantFoldGetElementPtr(Constant *C, 2128249259Sdim bool inBounds, 2129249259Sdim ArrayRef<Constant *> Idxs) { 2130249259Sdim return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); 2131249259Sdim} 2132249259Sdim 2133249259SdimConstant *llvm::ConstantFoldGetElementPtr(Constant *C, 2134249259Sdim bool inBounds, 2135249259Sdim ArrayRef<Value *> Idxs) { 2136249259Sdim return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); 2137249259Sdim} 2138