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" 25276479Sdim#include "llvm/IR/GetElementPtrTypeIterator.h" 26249259Sdim#include "llvm/IR/GlobalAlias.h" 27249259Sdim#include "llvm/IR/GlobalVariable.h" 28249259Sdim#include "llvm/IR/Instructions.h" 29249259Sdim#include "llvm/IR/Operator.h" 30280031Sdim#include "llvm/IR/PatternMatch.h" 31249259Sdim#include "llvm/Support/Compiler.h" 32249259Sdim#include "llvm/Support/ErrorHandling.h" 33249259Sdim#include "llvm/Support/ManagedStatic.h" 34249259Sdim#include "llvm/Support/MathExtras.h" 35249259Sdim#include <limits> 36249259Sdimusing namespace llvm; 37280031Sdimusing namespace llvm::PatternMatch; 38249259Sdim 39249259Sdim//===----------------------------------------------------------------------===// 40249259Sdim// ConstantFold*Instruction Implementations 41249259Sdim//===----------------------------------------------------------------------===// 42249259Sdim 43249259Sdim/// BitCastConstantVector - Convert the specified vector Constant node to the 44249259Sdim/// specified vector type. At this point, we know that the elements of the 45249259Sdim/// input vector constant are all simple integer or FP values. 46249259Sdimstatic Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) { 47249259Sdim 48249259Sdim if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy); 49249259Sdim if (CV->isNullValue()) return Constant::getNullValue(DstTy); 50249259Sdim 51249259Sdim // If this cast changes element count then we can't handle it here: 52249259Sdim // doing so requires endianness information. This should be handled by 53249259Sdim // Analysis/ConstantFolding.cpp 54249259Sdim unsigned NumElts = DstTy->getNumElements(); 55249259Sdim if (NumElts != CV->getType()->getVectorNumElements()) 56276479Sdim return nullptr; 57249259Sdim 58249259Sdim Type *DstEltTy = DstTy->getElementType(); 59249259Sdim 60249259Sdim SmallVector<Constant*, 16> Result; 61249259Sdim Type *Ty = IntegerType::get(CV->getContext(), 32); 62249259Sdim for (unsigned i = 0; i != NumElts; ++i) { 63249259Sdim Constant *C = 64249259Sdim ConstantExpr::getExtractElement(CV, ConstantInt::get(Ty, i)); 65249259Sdim C = ConstantExpr::getBitCast(C, DstEltTy); 66249259Sdim Result.push_back(C); 67249259Sdim } 68249259Sdim 69249259Sdim return ConstantVector::get(Result); 70249259Sdim} 71249259Sdim 72249259Sdim/// This function determines which opcode to use to fold two constant cast 73249259Sdim/// expressions together. It uses CastInst::isEliminableCastPair to determine 74249259Sdim/// the opcode. Consequently its just a wrapper around that function. 75249259Sdim/// @brief Determine if it is valid to fold a cast of a cast 76249259Sdimstatic unsigned 77249259SdimfoldConstantCastPair( 78249259Sdim unsigned opc, ///< opcode of the second cast constant expression 79249259Sdim ConstantExpr *Op, ///< the first cast constant expression 80261991Sdim Type *DstTy ///< destination type of the first cast 81249259Sdim) { 82249259Sdim assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!"); 83249259Sdim assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type"); 84249259Sdim assert(CastInst::isCast(opc) && "Invalid cast opcode"); 85249259Sdim 86296417Sdim // The types and opcodes for the two Cast constant expressions 87249259Sdim Type *SrcTy = Op->getOperand(0)->getType(); 88249259Sdim Type *MidTy = Op->getType(); 89249259Sdim Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode()); 90249259Sdim Instruction::CastOps secondOp = Instruction::CastOps(opc); 91249259Sdim 92261991Sdim // Assume that pointers are never more than 64 bits wide, and only use this 93261991Sdim // for the middle type. Otherwise we could end up folding away illegal 94261991Sdim // bitcasts between address spaces with different sizes. 95249259Sdim IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext()); 96249259Sdim 97249259Sdim // Let CastInst::isEliminableCastPair do the heavy lifting. 98249259Sdim return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy, 99276479Sdim nullptr, FakeIntPtrTy, nullptr); 100249259Sdim} 101249259Sdim 102249259Sdimstatic Constant *FoldBitCast(Constant *V, Type *DestTy) { 103249259Sdim Type *SrcTy = V->getType(); 104249259Sdim if (SrcTy == DestTy) 105249259Sdim return V; // no-op cast 106249259Sdim 107249259Sdim // Check to see if we are casting a pointer to an aggregate to a pointer to 108249259Sdim // the first element. If so, return the appropriate GEP instruction. 109249259Sdim if (PointerType *PTy = dyn_cast<PointerType>(V->getType())) 110249259Sdim if (PointerType *DPTy = dyn_cast<PointerType>(DestTy)) 111249259Sdim if (PTy->getAddressSpace() == DPTy->getAddressSpace() 112296417Sdim && PTy->getElementType()->isSized()) { 113249259Sdim SmallVector<Value*, 8> IdxList; 114249259Sdim Value *Zero = 115249259Sdim Constant::getNullValue(Type::getInt32Ty(DPTy->getContext())); 116249259Sdim IdxList.push_back(Zero); 117249259Sdim Type *ElTy = PTy->getElementType(); 118249259Sdim while (ElTy != DPTy->getElementType()) { 119249259Sdim if (StructType *STy = dyn_cast<StructType>(ElTy)) { 120249259Sdim if (STy->getNumElements() == 0) break; 121249259Sdim ElTy = STy->getElementType(0); 122249259Sdim IdxList.push_back(Zero); 123249259Sdim } else if (SequentialType *STy = 124249259Sdim dyn_cast<SequentialType>(ElTy)) { 125249259Sdim if (ElTy->isPointerTy()) break; // Can't index into pointers! 126249259Sdim ElTy = STy->getElementType(); 127249259Sdim IdxList.push_back(Zero); 128249259Sdim } else { 129249259Sdim break; 130249259Sdim } 131249259Sdim } 132249259Sdim 133249259Sdim if (ElTy == DPTy->getElementType()) 134249259Sdim // This GEP is inbounds because all indices are zero. 135288943Sdim return ConstantExpr::getInBoundsGetElementPtr(PTy->getElementType(), 136288943Sdim V, IdxList); 137249259Sdim } 138249259Sdim 139249259Sdim // Handle casts from one vector constant to another. We know that the src 140249259Sdim // and dest type have the same size (otherwise its an illegal cast). 141249259Sdim if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { 142249259Sdim if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { 143249259Sdim assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && 144249259Sdim "Not cast between same sized vectors!"); 145276479Sdim SrcTy = nullptr; 146249259Sdim // First, check for null. Undef is already handled. 147249259Sdim if (isa<ConstantAggregateZero>(V)) 148249259Sdim return Constant::getNullValue(DestTy); 149249259Sdim 150249259Sdim // Handle ConstantVector and ConstantAggregateVector. 151249259Sdim return BitCastConstantVector(V, DestPTy); 152249259Sdim } 153249259Sdim 154249259Sdim // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts 155249259Sdim // This allows for other simplifications (although some of them 156249259Sdim // can only be handled by Analysis/ConstantFolding.cpp). 157249259Sdim if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) 158249259Sdim return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy); 159249259Sdim } 160249259Sdim 161249259Sdim // Finally, implement bitcast folding now. The code below doesn't handle 162249259Sdim // bitcast right. 163249259Sdim if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. 164249259Sdim return ConstantPointerNull::get(cast<PointerType>(DestTy)); 165249259Sdim 166249259Sdim // Handle integral constant input. 167249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 168249259Sdim if (DestTy->isIntegerTy()) 169249259Sdim // Integral -> Integral. This is a no-op because the bit widths must 170249259Sdim // be the same. Consequently, we just fold to V. 171249259Sdim return V; 172249259Sdim 173288943Sdim // See note below regarding the PPC_FP128 restriction. 174288943Sdim if (DestTy->isFloatingPointTy() && !DestTy->isPPC_FP128Ty()) 175249259Sdim return ConstantFP::get(DestTy->getContext(), 176249259Sdim APFloat(DestTy->getFltSemantics(), 177249259Sdim CI->getValue())); 178249259Sdim 179249259Sdim // Otherwise, can't fold this (vector?) 180276479Sdim return nullptr; 181249259Sdim } 182249259Sdim 183249259Sdim // Handle ConstantFP input: FP -> Integral. 184288943Sdim if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) { 185288943Sdim // PPC_FP128 is really the sum of two consecutive doubles, where the first 186288943Sdim // double is always stored first in memory, regardless of the target 187288943Sdim // endianness. The memory layout of i128, however, depends on the target 188288943Sdim // endianness, and so we can't fold this without target endianness 189288943Sdim // information. This should instead be handled by 190288943Sdim // Analysis/ConstantFolding.cpp 191288943Sdim if (FP->getType()->isPPC_FP128Ty()) 192288943Sdim return nullptr; 193288943Sdim 194249259Sdim return ConstantInt::get(FP->getContext(), 195249259Sdim FP->getValueAPF().bitcastToAPInt()); 196288943Sdim } 197249259Sdim 198276479Sdim return nullptr; 199249259Sdim} 200249259Sdim 201249259Sdim 202249259Sdim/// ExtractConstantBytes - V is an integer constant which only has a subset of 203249259Sdim/// its bytes used. The bytes used are indicated by ByteStart (which is the 204249259Sdim/// first byte used, counting from the least significant byte) and ByteSize, 205249259Sdim/// which is the number of bytes used. 206249259Sdim/// 207249259Sdim/// This function analyzes the specified constant to see if the specified byte 208249259Sdim/// range can be returned as a simplified constant. If so, the constant is 209249259Sdim/// returned, otherwise null is returned. 210249259Sdim/// 211249259Sdimstatic Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, 212249259Sdim unsigned ByteSize) { 213249259Sdim assert(C->getType()->isIntegerTy() && 214249259Sdim (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 && 215249259Sdim "Non-byte sized integer input"); 216249259Sdim unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; 217249259Sdim assert(ByteSize && "Must be accessing some piece"); 218249259Sdim assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input"); 219249259Sdim assert(ByteSize != CSize && "Should not extract everything"); 220249259Sdim 221249259Sdim // Constant Integers are simple. 222249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { 223249259Sdim APInt V = CI->getValue(); 224249259Sdim if (ByteStart) 225249259Sdim V = V.lshr(ByteStart*8); 226249259Sdim V = V.trunc(ByteSize*8); 227249259Sdim return ConstantInt::get(CI->getContext(), V); 228249259Sdim } 229249259Sdim 230249259Sdim // In the input is a constant expr, we might be able to recursively simplify. 231249259Sdim // If not, we definitely can't do anything. 232249259Sdim ConstantExpr *CE = dyn_cast<ConstantExpr>(C); 233276479Sdim if (!CE) return nullptr; 234276479Sdim 235249259Sdim switch (CE->getOpcode()) { 236276479Sdim default: return nullptr; 237249259Sdim case Instruction::Or: { 238249259Sdim Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 239276479Sdim if (!RHS) 240276479Sdim return nullptr; 241249259Sdim 242249259Sdim // X | -1 -> -1. 243249259Sdim if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) 244249259Sdim if (RHSC->isAllOnesValue()) 245249259Sdim return RHSC; 246249259Sdim 247249259Sdim Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 248276479Sdim if (!LHS) 249276479Sdim return nullptr; 250249259Sdim return ConstantExpr::getOr(LHS, RHS); 251249259Sdim } 252249259Sdim case Instruction::And: { 253249259Sdim Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); 254276479Sdim if (!RHS) 255276479Sdim return nullptr; 256249259Sdim 257249259Sdim // X & 0 -> 0. 258249259Sdim if (RHS->isNullValue()) 259249259Sdim return RHS; 260249259Sdim 261249259Sdim Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); 262276479Sdim if (!LHS) 263276479Sdim return nullptr; 264249259Sdim return ConstantExpr::getAnd(LHS, RHS); 265249259Sdim } 266249259Sdim case Instruction::LShr: { 267249259Sdim ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 268276479Sdim if (!Amt) 269276479Sdim return nullptr; 270249259Sdim unsigned ShAmt = Amt->getZExtValue(); 271249259Sdim // Cannot analyze non-byte shifts. 272249259Sdim if ((ShAmt & 7) != 0) 273276479Sdim return nullptr; 274249259Sdim ShAmt >>= 3; 275249259Sdim 276249259Sdim // If the extract is known to be all zeros, return zero. 277249259Sdim if (ByteStart >= CSize-ShAmt) 278249259Sdim return Constant::getNullValue(IntegerType::get(CE->getContext(), 279249259Sdim ByteSize*8)); 280249259Sdim // If the extract is known to be fully in the input, extract it. 281249259Sdim if (ByteStart+ByteSize+ShAmt <= CSize) 282249259Sdim return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize); 283249259Sdim 284249259Sdim // TODO: Handle the 'partially zero' case. 285276479Sdim return nullptr; 286249259Sdim } 287249259Sdim 288249259Sdim case Instruction::Shl: { 289249259Sdim ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); 290276479Sdim if (!Amt) 291276479Sdim return nullptr; 292249259Sdim unsigned ShAmt = Amt->getZExtValue(); 293249259Sdim // Cannot analyze non-byte shifts. 294249259Sdim if ((ShAmt & 7) != 0) 295276479Sdim return nullptr; 296249259Sdim ShAmt >>= 3; 297249259Sdim 298249259Sdim // If the extract is known to be all zeros, return zero. 299249259Sdim if (ByteStart+ByteSize <= ShAmt) 300249259Sdim return Constant::getNullValue(IntegerType::get(CE->getContext(), 301249259Sdim ByteSize*8)); 302249259Sdim // If the extract is known to be fully in the input, extract it. 303249259Sdim if (ByteStart >= ShAmt) 304249259Sdim return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize); 305249259Sdim 306249259Sdim // TODO: Handle the 'partially zero' case. 307276479Sdim return nullptr; 308249259Sdim } 309249259Sdim 310249259Sdim case Instruction::ZExt: { 311249259Sdim unsigned SrcBitSize = 312249259Sdim cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth(); 313249259Sdim 314249259Sdim // If extracting something that is completely zero, return 0. 315249259Sdim if (ByteStart*8 >= SrcBitSize) 316249259Sdim return Constant::getNullValue(IntegerType::get(CE->getContext(), 317249259Sdim ByteSize*8)); 318249259Sdim 319249259Sdim // If exactly extracting the input, return it. 320249259Sdim if (ByteStart == 0 && ByteSize*8 == SrcBitSize) 321249259Sdim return CE->getOperand(0); 322249259Sdim 323249259Sdim // If extracting something completely in the input, if if the input is a 324249259Sdim // multiple of 8 bits, recurse. 325249259Sdim if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize) 326249259Sdim return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize); 327249259Sdim 328249259Sdim // Otherwise, if extracting a subset of the input, which is not multiple of 329249259Sdim // 8 bits, do a shift and trunc to get the bits. 330249259Sdim if ((ByteStart+ByteSize)*8 < SrcBitSize) { 331249259Sdim assert((SrcBitSize&7) && "Shouldn't get byte sized case here"); 332249259Sdim Constant *Res = CE->getOperand(0); 333249259Sdim if (ByteStart) 334249259Sdim Res = ConstantExpr::getLShr(Res, 335249259Sdim ConstantInt::get(Res->getType(), ByteStart*8)); 336249259Sdim return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(), 337249259Sdim ByteSize*8)); 338249259Sdim } 339249259Sdim 340249259Sdim // TODO: Handle the 'partially zero' case. 341276479Sdim return nullptr; 342249259Sdim } 343249259Sdim } 344249259Sdim} 345249259Sdim 346249259Sdim/// getFoldedSizeOf - Return a ConstantExpr with type DestTy for sizeof 347249259Sdim/// on Ty, with any known factors factored out. If Folded is false, 348249259Sdim/// return null if no factoring was possible, to avoid endlessly 349249259Sdim/// bouncing an unfoldable expression back into the top-level folder. 350249259Sdim/// 351249259Sdimstatic Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, 352249259Sdim bool Folded) { 353249259Sdim if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 354249259Sdim Constant *N = ConstantInt::get(DestTy, ATy->getNumElements()); 355249259Sdim Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); 356249259Sdim return ConstantExpr::getNUWMul(E, N); 357249259Sdim } 358249259Sdim 359249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) 360249259Sdim if (!STy->isPacked()) { 361249259Sdim unsigned NumElems = STy->getNumElements(); 362249259Sdim // An empty struct has size zero. 363249259Sdim if (NumElems == 0) 364249259Sdim return ConstantExpr::getNullValue(DestTy); 365249259Sdim // Check for a struct with all members having the same size. 366249259Sdim Constant *MemberSize = 367249259Sdim getFoldedSizeOf(STy->getElementType(0), DestTy, true); 368249259Sdim bool AllSame = true; 369249259Sdim for (unsigned i = 1; i != NumElems; ++i) 370249259Sdim if (MemberSize != 371249259Sdim getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { 372249259Sdim AllSame = false; 373249259Sdim break; 374249259Sdim } 375249259Sdim if (AllSame) { 376249259Sdim Constant *N = ConstantInt::get(DestTy, NumElems); 377249259Sdim return ConstantExpr::getNUWMul(MemberSize, N); 378249259Sdim } 379249259Sdim } 380249259Sdim 381249259Sdim // Pointer size doesn't depend on the pointee type, so canonicalize them 382249259Sdim // to an arbitrary pointee. 383249259Sdim if (PointerType *PTy = dyn_cast<PointerType>(Ty)) 384249259Sdim if (!PTy->getElementType()->isIntegerTy(1)) 385249259Sdim return 386249259Sdim getFoldedSizeOf(PointerType::get(IntegerType::get(PTy->getContext(), 1), 387249259Sdim PTy->getAddressSpace()), 388249259Sdim DestTy, true); 389249259Sdim 390249259Sdim // If there's no interesting folding happening, bail so that we don't create 391249259Sdim // a constant that looks like it needs folding but really doesn't. 392249259Sdim if (!Folded) 393276479Sdim return nullptr; 394249259Sdim 395249259Sdim // Base case: Get a regular sizeof expression. 396249259Sdim Constant *C = ConstantExpr::getSizeOf(Ty); 397249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 398249259Sdim DestTy, false), 399249259Sdim C, DestTy); 400249259Sdim return C; 401249259Sdim} 402249259Sdim 403249259Sdim/// getFoldedAlignOf - Return a ConstantExpr with type DestTy for alignof 404249259Sdim/// on Ty, with any known factors factored out. If Folded is false, 405249259Sdim/// return null if no factoring was possible, to avoid endlessly 406249259Sdim/// bouncing an unfoldable expression back into the top-level folder. 407249259Sdim/// 408249259Sdimstatic Constant *getFoldedAlignOf(Type *Ty, Type *DestTy, 409249259Sdim bool Folded) { 410249259Sdim // The alignment of an array is equal to the alignment of the 411249259Sdim // array element. Note that this is not always true for vectors. 412249259Sdim if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 413249259Sdim Constant *C = ConstantExpr::getAlignOf(ATy->getElementType()); 414249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 415249259Sdim DestTy, 416249259Sdim false), 417249259Sdim C, DestTy); 418249259Sdim return C; 419249259Sdim } 420249259Sdim 421249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) { 422249259Sdim // Packed structs always have an alignment of 1. 423249259Sdim if (STy->isPacked()) 424249259Sdim return ConstantInt::get(DestTy, 1); 425249259Sdim 426249259Sdim // Otherwise, struct alignment is the maximum alignment of any member. 427249259Sdim // Without target data, we can't compare much, but we can check to see 428249259Sdim // if all the members have the same alignment. 429249259Sdim unsigned NumElems = STy->getNumElements(); 430249259Sdim // An empty struct has minimal alignment. 431249259Sdim if (NumElems == 0) 432249259Sdim return ConstantInt::get(DestTy, 1); 433249259Sdim // Check for a struct with all members having the same alignment. 434249259Sdim Constant *MemberAlign = 435249259Sdim getFoldedAlignOf(STy->getElementType(0), DestTy, true); 436249259Sdim bool AllSame = true; 437249259Sdim for (unsigned i = 1; i != NumElems; ++i) 438249259Sdim if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) { 439249259Sdim AllSame = false; 440249259Sdim break; 441249259Sdim } 442249259Sdim if (AllSame) 443249259Sdim return MemberAlign; 444249259Sdim } 445249259Sdim 446249259Sdim // Pointer alignment doesn't depend on the pointee type, so canonicalize them 447249259Sdim // to an arbitrary pointee. 448249259Sdim if (PointerType *PTy = dyn_cast<PointerType>(Ty)) 449249259Sdim if (!PTy->getElementType()->isIntegerTy(1)) 450249259Sdim return 451249259Sdim getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(), 452249259Sdim 1), 453249259Sdim PTy->getAddressSpace()), 454249259Sdim DestTy, true); 455249259Sdim 456249259Sdim // If there's no interesting folding happening, bail so that we don't create 457249259Sdim // a constant that looks like it needs folding but really doesn't. 458249259Sdim if (!Folded) 459276479Sdim return nullptr; 460249259Sdim 461249259Sdim // Base case: Get a regular alignof expression. 462249259Sdim Constant *C = ConstantExpr::getAlignOf(Ty); 463249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 464249259Sdim DestTy, false), 465249259Sdim C, DestTy); 466249259Sdim return C; 467249259Sdim} 468249259Sdim 469249259Sdim/// getFoldedOffsetOf - Return a ConstantExpr with type DestTy for offsetof 470249259Sdim/// on Ty and FieldNo, with any known factors factored out. If Folded is false, 471249259Sdim/// return null if no factoring was possible, to avoid endlessly 472249259Sdim/// bouncing an unfoldable expression back into the top-level folder. 473249259Sdim/// 474249259Sdimstatic Constant *getFoldedOffsetOf(Type *Ty, Constant *FieldNo, 475249259Sdim Type *DestTy, 476249259Sdim bool Folded) { 477249259Sdim if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 478249259Sdim Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false, 479249259Sdim DestTy, false), 480249259Sdim FieldNo, DestTy); 481249259Sdim Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); 482249259Sdim return ConstantExpr::getNUWMul(E, N); 483249259Sdim } 484249259Sdim 485249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) 486249259Sdim if (!STy->isPacked()) { 487249259Sdim unsigned NumElems = STy->getNumElements(); 488249259Sdim // An empty struct has no members. 489249259Sdim if (NumElems == 0) 490276479Sdim return nullptr; 491249259Sdim // Check for a struct with all members having the same size. 492249259Sdim Constant *MemberSize = 493249259Sdim getFoldedSizeOf(STy->getElementType(0), DestTy, true); 494249259Sdim bool AllSame = true; 495249259Sdim for (unsigned i = 1; i != NumElems; ++i) 496249259Sdim if (MemberSize != 497249259Sdim getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { 498249259Sdim AllSame = false; 499249259Sdim break; 500249259Sdim } 501249259Sdim if (AllSame) { 502249259Sdim Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, 503249259Sdim false, 504249259Sdim DestTy, 505249259Sdim false), 506249259Sdim FieldNo, DestTy); 507249259Sdim return ConstantExpr::getNUWMul(MemberSize, N); 508249259Sdim } 509249259Sdim } 510249259Sdim 511249259Sdim // If there's no interesting folding happening, bail so that we don't create 512249259Sdim // a constant that looks like it needs folding but really doesn't. 513249259Sdim if (!Folded) 514276479Sdim return nullptr; 515249259Sdim 516249259Sdim // Base case: Get a regular offsetof expression. 517249259Sdim Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo); 518249259Sdim C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, 519249259Sdim DestTy, false), 520249259Sdim C, DestTy); 521249259Sdim return C; 522249259Sdim} 523249259Sdim 524249259SdimConstant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, 525249259Sdim Type *DestTy) { 526249259Sdim if (isa<UndefValue>(V)) { 527249259Sdim // zext(undef) = 0, because the top bits will be zero. 528249259Sdim // sext(undef) = 0, because the top bits will all be the same. 529249259Sdim // [us]itofp(undef) = 0, because the result value is bounded. 530249259Sdim if (opc == Instruction::ZExt || opc == Instruction::SExt || 531249259Sdim opc == Instruction::UIToFP || opc == Instruction::SIToFP) 532249259Sdim return Constant::getNullValue(DestTy); 533249259Sdim return UndefValue::get(DestTy); 534249259Sdim } 535249259Sdim 536249259Sdim if (V->isNullValue() && !DestTy->isX86_MMXTy()) 537249259Sdim return Constant::getNullValue(DestTy); 538249259Sdim 539249259Sdim // If the cast operand is a constant expression, there's a few things we can 540249259Sdim // do to try to simplify it. 541249259Sdim if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 542249259Sdim if (CE->isCast()) { 543249259Sdim // Try hard to fold cast of cast because they are often eliminable. 544249259Sdim if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) 545249259Sdim return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); 546276479Sdim } else if (CE->getOpcode() == Instruction::GetElementPtr && 547276479Sdim // Do not fold addrspacecast (gep 0, .., 0). It might make the 548276479Sdim // addrspacecast uncanonicalized. 549276479Sdim opc != Instruction::AddrSpaceCast) { 550249259Sdim // If all of the indexes in the GEP are null values, there is no pointer 551249259Sdim // adjustment going on. We might as well cast the source pointer. 552249259Sdim bool isAllNull = true; 553249259Sdim for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) 554249259Sdim if (!CE->getOperand(i)->isNullValue()) { 555249259Sdim isAllNull = false; 556249259Sdim break; 557249259Sdim } 558249259Sdim if (isAllNull) 559249259Sdim // This is casting one pointer type to another, always BitCast 560249259Sdim return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); 561249259Sdim } 562249259Sdim } 563249259Sdim 564249259Sdim // If the cast operand is a constant vector, perform the cast by 565249259Sdim // operating on each element. In the cast of bitcasts, the element 566249259Sdim // count may be mismatched; don't attempt to handle that here. 567249259Sdim if ((isa<ConstantVector>(V) || isa<ConstantDataVector>(V)) && 568249259Sdim DestTy->isVectorTy() && 569249259Sdim DestTy->getVectorNumElements() == V->getType()->getVectorNumElements()) { 570249259Sdim SmallVector<Constant*, 16> res; 571249259Sdim VectorType *DestVecTy = cast<VectorType>(DestTy); 572249259Sdim Type *DstEltTy = DestVecTy->getElementType(); 573249259Sdim Type *Ty = IntegerType::get(V->getContext(), 32); 574249259Sdim for (unsigned i = 0, e = V->getType()->getVectorNumElements(); i != e; ++i) { 575249259Sdim Constant *C = 576249259Sdim ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i)); 577249259Sdim res.push_back(ConstantExpr::getCast(opc, C, DstEltTy)); 578249259Sdim } 579249259Sdim return ConstantVector::get(res); 580249259Sdim } 581249259Sdim 582249259Sdim // We actually have to do a cast now. Perform the cast according to the 583249259Sdim // opcode specified. 584249259Sdim switch (opc) { 585249259Sdim default: 586249259Sdim llvm_unreachable("Failed to cast constant expression"); 587249259Sdim case Instruction::FPTrunc: 588249259Sdim case Instruction::FPExt: 589249259Sdim if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 590249259Sdim bool ignored; 591249259Sdim APFloat Val = FPC->getValueAPF(); 592249259Sdim Val.convert(DestTy->isHalfTy() ? APFloat::IEEEhalf : 593249259Sdim DestTy->isFloatTy() ? APFloat::IEEEsingle : 594249259Sdim DestTy->isDoubleTy() ? APFloat::IEEEdouble : 595249259Sdim DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended : 596249259Sdim DestTy->isFP128Ty() ? APFloat::IEEEquad : 597249259Sdim DestTy->isPPC_FP128Ty() ? APFloat::PPCDoubleDouble : 598249259Sdim APFloat::Bogus, 599249259Sdim APFloat::rmNearestTiesToEven, &ignored); 600249259Sdim return ConstantFP::get(V->getContext(), Val); 601249259Sdim } 602276479Sdim return nullptr; // Can't fold. 603249259Sdim case Instruction::FPToUI: 604249259Sdim case Instruction::FPToSI: 605249259Sdim if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { 606249259Sdim const APFloat &V = FPC->getValueAPF(); 607249259Sdim bool ignored; 608249259Sdim uint64_t x[2]; 609249259Sdim uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 610280031Sdim if (APFloat::opInvalidOp == 611280031Sdim V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, 612280031Sdim APFloat::rmTowardZero, &ignored)) { 613280031Sdim // Undefined behavior invoked - the destination type can't represent 614280031Sdim // the input constant. 615280031Sdim return UndefValue::get(DestTy); 616280031Sdim } 617249259Sdim APInt Val(DestBitWidth, x); 618249259Sdim return ConstantInt::get(FPC->getContext(), Val); 619249259Sdim } 620276479Sdim return nullptr; // Can't fold. 621249259Sdim case Instruction::IntToPtr: //always treated as unsigned 622249259Sdim if (V->isNullValue()) // Is it an integral null value? 623249259Sdim return ConstantPointerNull::get(cast<PointerType>(DestTy)); 624276479Sdim return nullptr; // Other pointer types cannot be casted 625249259Sdim case Instruction::PtrToInt: // always treated as unsigned 626249259Sdim // Is it a null pointer value? 627249259Sdim if (V->isNullValue()) 628249259Sdim return ConstantInt::get(DestTy, 0); 629249259Sdim // If this is a sizeof-like expression, pull out multiplications by 630249259Sdim // known factors to expose them to subsequent folding. If it's an 631249259Sdim // alignof-like expression, factor out known factors. 632249259Sdim if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 633249259Sdim if (CE->getOpcode() == Instruction::GetElementPtr && 634249259Sdim CE->getOperand(0)->isNullValue()) { 635288943Sdim GEPOperator *GEPO = cast<GEPOperator>(CE); 636288943Sdim Type *Ty = GEPO->getSourceElementType(); 637249259Sdim if (CE->getNumOperands() == 2) { 638249259Sdim // Handle a sizeof-like expression. 639249259Sdim Constant *Idx = CE->getOperand(1); 640249259Sdim bool isOne = isa<ConstantInt>(Idx) && cast<ConstantInt>(Idx)->isOne(); 641249259Sdim if (Constant *C = getFoldedSizeOf(Ty, DestTy, !isOne)) { 642249259Sdim Idx = ConstantExpr::getCast(CastInst::getCastOpcode(Idx, true, 643249259Sdim DestTy, false), 644249259Sdim Idx, DestTy); 645249259Sdim return ConstantExpr::getMul(C, Idx); 646249259Sdim } 647249259Sdim } else if (CE->getNumOperands() == 3 && 648249259Sdim CE->getOperand(1)->isNullValue()) { 649249259Sdim // Handle an alignof-like expression. 650249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) 651249259Sdim if (!STy->isPacked()) { 652249259Sdim ConstantInt *CI = cast<ConstantInt>(CE->getOperand(2)); 653249259Sdim if (CI->isOne() && 654249259Sdim STy->getNumElements() == 2 && 655249259Sdim STy->getElementType(0)->isIntegerTy(1)) { 656249259Sdim return getFoldedAlignOf(STy->getElementType(1), DestTy, false); 657249259Sdim } 658249259Sdim } 659249259Sdim // Handle an offsetof-like expression. 660249259Sdim if (Ty->isStructTy() || Ty->isArrayTy()) { 661249259Sdim if (Constant *C = getFoldedOffsetOf(Ty, CE->getOperand(2), 662249259Sdim DestTy, false)) 663249259Sdim return C; 664249259Sdim } 665249259Sdim } 666249259Sdim } 667249259Sdim // Other pointer types cannot be casted 668276479Sdim return nullptr; 669249259Sdim case Instruction::UIToFP: 670249259Sdim case Instruction::SIToFP: 671249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 672249259Sdim APInt api = CI->getValue(); 673249259Sdim APFloat apf(DestTy->getFltSemantics(), 674249259Sdim APInt::getNullValue(DestTy->getPrimitiveSizeInBits())); 675280031Sdim if (APFloat::opOverflow & 676280031Sdim apf.convertFromAPInt(api, opc==Instruction::SIToFP, 677280031Sdim APFloat::rmNearestTiesToEven)) { 678280031Sdim // Undefined behavior invoked - the destination type can't represent 679280031Sdim // the input constant. 680280031Sdim return UndefValue::get(DestTy); 681280031Sdim } 682249259Sdim return ConstantFP::get(V->getContext(), apf); 683249259Sdim } 684276479Sdim return nullptr; 685249259Sdim case Instruction::ZExt: 686249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 687249259Sdim uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 688249259Sdim return ConstantInt::get(V->getContext(), 689249259Sdim CI->getValue().zext(BitWidth)); 690249259Sdim } 691276479Sdim return nullptr; 692249259Sdim case Instruction::SExt: 693249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 694249259Sdim uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 695249259Sdim return ConstantInt::get(V->getContext(), 696249259Sdim CI->getValue().sext(BitWidth)); 697249259Sdim } 698276479Sdim return nullptr; 699249259Sdim case Instruction::Trunc: { 700280031Sdim if (V->getType()->isVectorTy()) 701280031Sdim return nullptr; 702280031Sdim 703249259Sdim uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); 704249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 705249259Sdim return ConstantInt::get(V->getContext(), 706249259Sdim CI->getValue().trunc(DestBitWidth)); 707249259Sdim } 708249259Sdim 709249259Sdim // The input must be a constantexpr. See if we can simplify this based on 710249259Sdim // the bytes we are demanding. Only do this if the source and dest are an 711249259Sdim // even multiple of a byte. 712249259Sdim if ((DestBitWidth & 7) == 0 && 713249259Sdim (cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0) 714249259Sdim if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8)) 715249259Sdim return Res; 716249259Sdim 717276479Sdim return nullptr; 718249259Sdim } 719249259Sdim case Instruction::BitCast: 720249259Sdim return FoldBitCast(V, DestTy); 721261991Sdim case Instruction::AddrSpaceCast: 722276479Sdim return nullptr; 723249259Sdim } 724249259Sdim} 725249259Sdim 726249259SdimConstant *llvm::ConstantFoldSelectInstruction(Constant *Cond, 727249259Sdim Constant *V1, Constant *V2) { 728249259Sdim // Check for i1 and vector true/false conditions. 729249259Sdim if (Cond->isNullValue()) return V2; 730249259Sdim if (Cond->isAllOnesValue()) return V1; 731249259Sdim 732249259Sdim // If the condition is a vector constant, fold the result elementwise. 733249259Sdim if (ConstantVector *CondV = dyn_cast<ConstantVector>(Cond)) { 734249259Sdim SmallVector<Constant*, 16> Result; 735249259Sdim Type *Ty = IntegerType::get(CondV->getContext(), 32); 736249259Sdim for (unsigned i = 0, e = V1->getType()->getVectorNumElements(); i != e;++i){ 737276479Sdim Constant *V; 738276479Sdim Constant *V1Element = ConstantExpr::getExtractElement(V1, 739276479Sdim ConstantInt::get(Ty, i)); 740276479Sdim Constant *V2Element = ConstantExpr::getExtractElement(V2, 741276479Sdim ConstantInt::get(Ty, i)); 742276479Sdim Constant *Cond = dyn_cast<Constant>(CondV->getOperand(i)); 743276479Sdim if (V1Element == V2Element) { 744276479Sdim V = V1Element; 745276479Sdim } else if (isa<UndefValue>(Cond)) { 746276479Sdim V = isa<UndefValue>(V1Element) ? V1Element : V2Element; 747276479Sdim } else { 748276479Sdim if (!isa<ConstantInt>(Cond)) break; 749276479Sdim V = Cond->isNullValue() ? V2Element : V1Element; 750276479Sdim } 751276479Sdim Result.push_back(V); 752249259Sdim } 753249259Sdim 754249259Sdim // If we were able to build the vector, return it. 755249259Sdim if (Result.size() == V1->getType()->getVectorNumElements()) 756249259Sdim return ConstantVector::get(Result); 757249259Sdim } 758249259Sdim 759249259Sdim if (isa<UndefValue>(Cond)) { 760249259Sdim if (isa<UndefValue>(V1)) return V1; 761249259Sdim return V2; 762249259Sdim } 763249259Sdim if (isa<UndefValue>(V1)) return V2; 764249259Sdim if (isa<UndefValue>(V2)) return V1; 765249259Sdim if (V1 == V2) return V1; 766249259Sdim 767249259Sdim if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) { 768249259Sdim if (TrueVal->getOpcode() == Instruction::Select) 769249259Sdim if (TrueVal->getOperand(0) == Cond) 770249259Sdim return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2); 771249259Sdim } 772249259Sdim if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) { 773249259Sdim if (FalseVal->getOpcode() == Instruction::Select) 774249259Sdim if (FalseVal->getOperand(0) == Cond) 775249259Sdim return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2)); 776249259Sdim } 777249259Sdim 778276479Sdim return nullptr; 779249259Sdim} 780249259Sdim 781249259SdimConstant *llvm::ConstantFoldExtractElementInstruction(Constant *Val, 782249259Sdim Constant *Idx) { 783249259Sdim if (isa<UndefValue>(Val)) // ee(undef, x) -> undef 784249259Sdim return UndefValue::get(Val->getType()->getVectorElementType()); 785249259Sdim if (Val->isNullValue()) // ee(zero, x) -> zero 786249259Sdim return Constant::getNullValue(Val->getType()->getVectorElementType()); 787249259Sdim // ee({w,x,y,z}, undef) -> undef 788249259Sdim if (isa<UndefValue>(Idx)) 789249259Sdim return UndefValue::get(Val->getType()->getVectorElementType()); 790249259Sdim 791249259Sdim if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { 792249259Sdim // ee({w,x,y,z}, wrong_value) -> undef 793288943Sdim if (CIdx->uge(Val->getType()->getVectorNumElements())) 794249259Sdim return UndefValue::get(Val->getType()->getVectorElementType()); 795288943Sdim return Val->getAggregateElement(CIdx->getZExtValue()); 796249259Sdim } 797276479Sdim return nullptr; 798249259Sdim} 799249259Sdim 800249259SdimConstant *llvm::ConstantFoldInsertElementInstruction(Constant *Val, 801249259Sdim Constant *Elt, 802249259Sdim Constant *Idx) { 803288943Sdim if (isa<UndefValue>(Idx)) 804288943Sdim return UndefValue::get(Val->getType()); 805288943Sdim 806249259Sdim ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); 807276479Sdim if (!CIdx) return nullptr; 808288943Sdim 809288943Sdim unsigned NumElts = Val->getType()->getVectorNumElements(); 810288943Sdim if (CIdx->uge(NumElts)) 811288943Sdim return UndefValue::get(Val->getType()); 812288943Sdim 813249259Sdim SmallVector<Constant*, 16> Result; 814288943Sdim Result.reserve(NumElts); 815288943Sdim auto *Ty = Type::getInt32Ty(Val->getContext()); 816288943Sdim uint64_t IdxVal = CIdx->getZExtValue(); 817288943Sdim for (unsigned i = 0; i != NumElts; ++i) { 818249259Sdim if (i == IdxVal) { 819249259Sdim Result.push_back(Elt); 820249259Sdim continue; 821249259Sdim } 822249259Sdim 823288943Sdim Constant *C = ConstantExpr::getExtractElement(Val, ConstantInt::get(Ty, i)); 824249259Sdim Result.push_back(C); 825249259Sdim } 826288943Sdim 827249259Sdim return ConstantVector::get(Result); 828249259Sdim} 829249259Sdim 830249259SdimConstant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1, 831249259Sdim Constant *V2, 832249259Sdim Constant *Mask) { 833249259Sdim unsigned MaskNumElts = Mask->getType()->getVectorNumElements(); 834249259Sdim Type *EltTy = V1->getType()->getVectorElementType(); 835249259Sdim 836249259Sdim // Undefined shuffle mask -> undefined value. 837249259Sdim if (isa<UndefValue>(Mask)) 838249259Sdim return UndefValue::get(VectorType::get(EltTy, MaskNumElts)); 839249259Sdim 840249259Sdim // Don't break the bitcode reader hack. 841276479Sdim if (isa<ConstantExpr>(Mask)) return nullptr; 842249259Sdim 843249259Sdim unsigned SrcNumElts = V1->getType()->getVectorNumElements(); 844249259Sdim 845249259Sdim // Loop over the shuffle mask, evaluating each element. 846249259Sdim SmallVector<Constant*, 32> Result; 847249259Sdim for (unsigned i = 0; i != MaskNumElts; ++i) { 848249259Sdim int Elt = ShuffleVectorInst::getMaskValue(Mask, i); 849249259Sdim if (Elt == -1) { 850249259Sdim Result.push_back(UndefValue::get(EltTy)); 851249259Sdim continue; 852249259Sdim } 853249259Sdim Constant *InElt; 854249259Sdim if (unsigned(Elt) >= SrcNumElts*2) 855249259Sdim InElt = UndefValue::get(EltTy); 856249259Sdim else if (unsigned(Elt) >= SrcNumElts) { 857249259Sdim Type *Ty = IntegerType::get(V2->getContext(), 32); 858249259Sdim InElt = 859249259Sdim ConstantExpr::getExtractElement(V2, 860249259Sdim ConstantInt::get(Ty, Elt - SrcNumElts)); 861249259Sdim } else { 862249259Sdim Type *Ty = IntegerType::get(V1->getContext(), 32); 863249259Sdim InElt = ConstantExpr::getExtractElement(V1, ConstantInt::get(Ty, Elt)); 864249259Sdim } 865249259Sdim Result.push_back(InElt); 866249259Sdim } 867249259Sdim 868249259Sdim return ConstantVector::get(Result); 869249259Sdim} 870249259Sdim 871249259SdimConstant *llvm::ConstantFoldExtractValueInstruction(Constant *Agg, 872249259Sdim ArrayRef<unsigned> Idxs) { 873249259Sdim // Base case: no indices, so return the entire value. 874249259Sdim if (Idxs.empty()) 875249259Sdim return Agg; 876249259Sdim 877249259Sdim if (Constant *C = Agg->getAggregateElement(Idxs[0])) 878249259Sdim return ConstantFoldExtractValueInstruction(C, Idxs.slice(1)); 879249259Sdim 880276479Sdim return nullptr; 881249259Sdim} 882249259Sdim 883249259SdimConstant *llvm::ConstantFoldInsertValueInstruction(Constant *Agg, 884249259Sdim Constant *Val, 885249259Sdim ArrayRef<unsigned> Idxs) { 886249259Sdim // Base case: no indices, so replace the entire value. 887249259Sdim if (Idxs.empty()) 888249259Sdim return Val; 889249259Sdim 890249259Sdim unsigned NumElts; 891249259Sdim if (StructType *ST = dyn_cast<StructType>(Agg->getType())) 892249259Sdim NumElts = ST->getNumElements(); 893249259Sdim else if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) 894249259Sdim NumElts = AT->getNumElements(); 895249259Sdim else 896249259Sdim NumElts = Agg->getType()->getVectorNumElements(); 897249259Sdim 898249259Sdim SmallVector<Constant*, 32> Result; 899249259Sdim for (unsigned i = 0; i != NumElts; ++i) { 900249259Sdim Constant *C = Agg->getAggregateElement(i); 901276479Sdim if (!C) return nullptr; 902276479Sdim 903249259Sdim if (Idxs[0] == i) 904249259Sdim C = ConstantFoldInsertValueInstruction(C, Val, Idxs.slice(1)); 905249259Sdim 906249259Sdim Result.push_back(C); 907249259Sdim } 908249259Sdim 909249259Sdim if (StructType *ST = dyn_cast<StructType>(Agg->getType())) 910249259Sdim return ConstantStruct::get(ST, Result); 911249259Sdim if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) 912249259Sdim return ConstantArray::get(AT, Result); 913249259Sdim return ConstantVector::get(Result); 914249259Sdim} 915249259Sdim 916249259Sdim 917249259SdimConstant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, 918249259Sdim Constant *C1, Constant *C2) { 919249259Sdim // Handle UndefValue up front. 920249259Sdim if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 921249259Sdim switch (Opcode) { 922249259Sdim case Instruction::Xor: 923249259Sdim if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) 924249259Sdim // Handle undef ^ undef -> 0 special case. This is a common 925249259Sdim // idiom (misuse). 926249259Sdim return Constant::getNullValue(C1->getType()); 927249259Sdim // Fallthrough 928249259Sdim case Instruction::Add: 929249259Sdim case Instruction::Sub: 930249259Sdim return UndefValue::get(C1->getType()); 931249259Sdim case Instruction::And: 932249259Sdim if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef & undef -> undef 933249259Sdim return C1; 934249259Sdim return Constant::getNullValue(C1->getType()); // undef & X -> 0 935249259Sdim case Instruction::Mul: { 936280031Sdim // undef * undef -> undef 937280031Sdim if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) 938280031Sdim return C1; 939280031Sdim const APInt *CV; 940280031Sdim // X * undef -> undef if X is odd 941280031Sdim if (match(C1, m_APInt(CV)) || match(C2, m_APInt(CV))) 942280031Sdim if ((*CV)[0]) 943280031Sdim return UndefValue::get(C1->getType()); 944249259Sdim 945249259Sdim // X * undef -> 0 otherwise 946249259Sdim return Constant::getNullValue(C1->getType()); 947249259Sdim } 948280031Sdim case Instruction::SDiv: 949249259Sdim case Instruction::UDiv: 950280031Sdim // X / undef -> undef 951280031Sdim if (match(C1, m_Zero())) 952280031Sdim return C2; 953280031Sdim // undef / 0 -> undef 954249259Sdim // undef / 1 -> undef 955280031Sdim if (match(C2, m_Zero()) || match(C2, m_One())) 956280031Sdim return C1; 957280031Sdim // undef / X -> 0 otherwise 958280031Sdim return Constant::getNullValue(C1->getType()); 959249259Sdim case Instruction::URem: 960249259Sdim case Instruction::SRem: 961280031Sdim // X % undef -> undef 962280031Sdim if (match(C2, m_Undef())) 963280031Sdim return C2; 964280031Sdim // undef % 0 -> undef 965280031Sdim if (match(C2, m_Zero())) 966280031Sdim return C1; 967280031Sdim // undef % X -> 0 otherwise 968280031Sdim return Constant::getNullValue(C1->getType()); 969249259Sdim case Instruction::Or: // X | undef -> -1 970249259Sdim if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef 971249259Sdim return C1; 972249259Sdim return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0 973249259Sdim case Instruction::LShr: 974280031Sdim // X >>l undef -> undef 975280031Sdim if (isa<UndefValue>(C2)) 976280031Sdim return C2; 977280031Sdim // undef >>l 0 -> undef 978280031Sdim if (match(C2, m_Zero())) 979280031Sdim return C1; 980280031Sdim // undef >>l X -> 0 981280031Sdim return Constant::getNullValue(C1->getType()); 982249259Sdim case Instruction::AShr: 983280031Sdim // X >>a undef -> undef 984280031Sdim if (isa<UndefValue>(C2)) 985280031Sdim return C2; 986280031Sdim // undef >>a 0 -> undef 987280031Sdim if (match(C2, m_Zero())) 988280031Sdim return C1; 989280031Sdim // TODO: undef >>a X -> undef if the shift is exact 990280031Sdim // undef >>a X -> 0 991280031Sdim return Constant::getNullValue(C1->getType()); 992249259Sdim case Instruction::Shl: 993280031Sdim // X << undef -> undef 994280031Sdim if (isa<UndefValue>(C2)) 995280031Sdim return C2; 996280031Sdim // undef << 0 -> undef 997280031Sdim if (match(C2, m_Zero())) 998280031Sdim return C1; 999280031Sdim // undef << X -> 0 1000249259Sdim return Constant::getNullValue(C1->getType()); 1001249259Sdim } 1002249259Sdim } 1003249259Sdim 1004249259Sdim // Handle simplifications when the RHS is a constant int. 1005249259Sdim if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 1006249259Sdim switch (Opcode) { 1007249259Sdim case Instruction::Add: 1008249259Sdim if (CI2->equalsInt(0)) return C1; // X + 0 == X 1009249259Sdim break; 1010249259Sdim case Instruction::Sub: 1011249259Sdim if (CI2->equalsInt(0)) return C1; // X - 0 == X 1012249259Sdim break; 1013249259Sdim case Instruction::Mul: 1014249259Sdim if (CI2->equalsInt(0)) return C2; // X * 0 == 0 1015249259Sdim if (CI2->equalsInt(1)) 1016249259Sdim return C1; // X * 1 == X 1017249259Sdim break; 1018249259Sdim case Instruction::UDiv: 1019249259Sdim case Instruction::SDiv: 1020249259Sdim if (CI2->equalsInt(1)) 1021249259Sdim return C1; // X / 1 == X 1022249259Sdim if (CI2->equalsInt(0)) 1023249259Sdim return UndefValue::get(CI2->getType()); // X / 0 == undef 1024249259Sdim break; 1025249259Sdim case Instruction::URem: 1026249259Sdim case Instruction::SRem: 1027249259Sdim if (CI2->equalsInt(1)) 1028249259Sdim return Constant::getNullValue(CI2->getType()); // X % 1 == 0 1029249259Sdim if (CI2->equalsInt(0)) 1030249259Sdim return UndefValue::get(CI2->getType()); // X % 0 == undef 1031249259Sdim break; 1032249259Sdim case Instruction::And: 1033249259Sdim if (CI2->isZero()) return C2; // X & 0 == 0 1034249259Sdim if (CI2->isAllOnesValue()) 1035249259Sdim return C1; // X & -1 == X 1036249259Sdim 1037249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1038249259Sdim // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) 1039249259Sdim if (CE1->getOpcode() == Instruction::ZExt) { 1040249259Sdim unsigned DstWidth = CI2->getType()->getBitWidth(); 1041249259Sdim unsigned SrcWidth = 1042249259Sdim CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); 1043249259Sdim APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); 1044249259Sdim if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) 1045249259Sdim return C1; 1046249259Sdim } 1047249259Sdim 1048249259Sdim // If and'ing the address of a global with a constant, fold it. 1049249259Sdim if (CE1->getOpcode() == Instruction::PtrToInt && 1050249259Sdim isa<GlobalValue>(CE1->getOperand(0))) { 1051249259Sdim GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0)); 1052249259Sdim 1053249259Sdim // Functions are at least 4-byte aligned. 1054249259Sdim unsigned GVAlign = GV->getAlignment(); 1055249259Sdim if (isa<Function>(GV)) 1056249259Sdim GVAlign = std::max(GVAlign, 4U); 1057249259Sdim 1058249259Sdim if (GVAlign > 1) { 1059249259Sdim unsigned DstWidth = CI2->getType()->getBitWidth(); 1060249259Sdim unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign)); 1061249259Sdim APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth)); 1062249259Sdim 1063249259Sdim // If checking bits we know are clear, return zero. 1064249259Sdim if ((CI2->getValue() & BitsNotSet) == CI2->getValue()) 1065249259Sdim return Constant::getNullValue(CI2->getType()); 1066249259Sdim } 1067249259Sdim } 1068249259Sdim } 1069249259Sdim break; 1070249259Sdim case Instruction::Or: 1071249259Sdim if (CI2->equalsInt(0)) return C1; // X | 0 == X 1072249259Sdim if (CI2->isAllOnesValue()) 1073249259Sdim return C2; // X | -1 == -1 1074249259Sdim break; 1075249259Sdim case Instruction::Xor: 1076249259Sdim if (CI2->equalsInt(0)) return C1; // X ^ 0 == X 1077249259Sdim 1078249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1079249259Sdim switch (CE1->getOpcode()) { 1080249259Sdim default: break; 1081249259Sdim case Instruction::ICmp: 1082249259Sdim case Instruction::FCmp: 1083249259Sdim // cmp pred ^ true -> cmp !pred 1084249259Sdim assert(CI2->equalsInt(1)); 1085249259Sdim CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate(); 1086249259Sdim pred = CmpInst::getInversePredicate(pred); 1087249259Sdim return ConstantExpr::getCompare(pred, CE1->getOperand(0), 1088249259Sdim CE1->getOperand(1)); 1089249259Sdim } 1090249259Sdim } 1091249259Sdim break; 1092249259Sdim case Instruction::AShr: 1093249259Sdim // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 1094249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) 1095249259Sdim if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. 1096249259Sdim return ConstantExpr::getLShr(C1, C2); 1097249259Sdim break; 1098249259Sdim } 1099249259Sdim } else if (isa<ConstantInt>(C1)) { 1100249259Sdim // If C1 is a ConstantInt and C2 is not, swap the operands. 1101249259Sdim if (Instruction::isCommutative(Opcode)) 1102249259Sdim return ConstantExpr::get(Opcode, C2, C1); 1103249259Sdim } 1104249259Sdim 1105249259Sdim // At this point we know neither constant is an UndefValue. 1106249259Sdim if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { 1107249259Sdim if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { 1108249259Sdim const APInt &C1V = CI1->getValue(); 1109249259Sdim const APInt &C2V = CI2->getValue(); 1110249259Sdim switch (Opcode) { 1111249259Sdim default: 1112249259Sdim break; 1113249259Sdim case Instruction::Add: 1114249259Sdim return ConstantInt::get(CI1->getContext(), C1V + C2V); 1115249259Sdim case Instruction::Sub: 1116249259Sdim return ConstantInt::get(CI1->getContext(), C1V - C2V); 1117249259Sdim case Instruction::Mul: 1118249259Sdim return ConstantInt::get(CI1->getContext(), C1V * C2V); 1119249259Sdim case Instruction::UDiv: 1120249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1121249259Sdim return ConstantInt::get(CI1->getContext(), C1V.udiv(C2V)); 1122249259Sdim case Instruction::SDiv: 1123249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1124249259Sdim if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 1125249259Sdim return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef 1126249259Sdim return ConstantInt::get(CI1->getContext(), C1V.sdiv(C2V)); 1127249259Sdim case Instruction::URem: 1128249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1129249259Sdim return ConstantInt::get(CI1->getContext(), C1V.urem(C2V)); 1130249259Sdim case Instruction::SRem: 1131249259Sdim assert(!CI2->isNullValue() && "Div by zero handled above"); 1132249259Sdim if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) 1133249259Sdim return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef 1134249259Sdim return ConstantInt::get(CI1->getContext(), C1V.srem(C2V)); 1135249259Sdim case Instruction::And: 1136249259Sdim return ConstantInt::get(CI1->getContext(), C1V & C2V); 1137249259Sdim case Instruction::Or: 1138249259Sdim return ConstantInt::get(CI1->getContext(), C1V | C2V); 1139249259Sdim case Instruction::Xor: 1140249259Sdim return ConstantInt::get(CI1->getContext(), C1V ^ C2V); 1141283526Sdim case Instruction::Shl: 1142283526Sdim if (C2V.ult(C1V.getBitWidth())) 1143283526Sdim return ConstantInt::get(CI1->getContext(), C1V.shl(C2V)); 1144283526Sdim return UndefValue::get(C1->getType()); // too big shift is undef 1145283526Sdim case Instruction::LShr: 1146283526Sdim if (C2V.ult(C1V.getBitWidth())) 1147283526Sdim return ConstantInt::get(CI1->getContext(), C1V.lshr(C2V)); 1148283526Sdim return UndefValue::get(C1->getType()); // too big shift is undef 1149283526Sdim case Instruction::AShr: 1150283526Sdim if (C2V.ult(C1V.getBitWidth())) 1151283526Sdim return ConstantInt::get(CI1->getContext(), C1V.ashr(C2V)); 1152283526Sdim return UndefValue::get(C1->getType()); // too big shift is undef 1153249259Sdim } 1154249259Sdim } 1155249259Sdim 1156249259Sdim switch (Opcode) { 1157249259Sdim case Instruction::SDiv: 1158249259Sdim case Instruction::UDiv: 1159249259Sdim case Instruction::URem: 1160249259Sdim case Instruction::SRem: 1161249259Sdim case Instruction::LShr: 1162249259Sdim case Instruction::AShr: 1163249259Sdim case Instruction::Shl: 1164249259Sdim if (CI1->equalsInt(0)) return C1; 1165249259Sdim break; 1166249259Sdim default: 1167249259Sdim break; 1168249259Sdim } 1169249259Sdim } else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { 1170249259Sdim if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { 1171249259Sdim APFloat C1V = CFP1->getValueAPF(); 1172249259Sdim APFloat C2V = CFP2->getValueAPF(); 1173249259Sdim APFloat C3V = C1V; // copy for modification 1174249259Sdim switch (Opcode) { 1175249259Sdim default: 1176249259Sdim break; 1177249259Sdim case Instruction::FAdd: 1178249259Sdim (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); 1179249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1180249259Sdim case Instruction::FSub: 1181249259Sdim (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); 1182249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1183249259Sdim case Instruction::FMul: 1184249259Sdim (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); 1185249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1186249259Sdim case Instruction::FDiv: 1187249259Sdim (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); 1188249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1189249259Sdim case Instruction::FRem: 1190296417Sdim (void)C3V.mod(C2V); 1191249259Sdim return ConstantFP::get(C1->getContext(), C3V); 1192249259Sdim } 1193249259Sdim } 1194249259Sdim } else if (VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { 1195249259Sdim // Perform elementwise folding. 1196249259Sdim SmallVector<Constant*, 16> Result; 1197249259Sdim Type *Ty = IntegerType::get(VTy->getContext(), 32); 1198249259Sdim for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 1199249259Sdim Constant *LHS = 1200249259Sdim ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, i)); 1201249259Sdim Constant *RHS = 1202249259Sdim ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, i)); 1203249259Sdim 1204249259Sdim Result.push_back(ConstantExpr::get(Opcode, LHS, RHS)); 1205249259Sdim } 1206249259Sdim 1207249259Sdim return ConstantVector::get(Result); 1208249259Sdim } 1209249259Sdim 1210249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1211249259Sdim // There are many possible foldings we could do here. We should probably 1212249259Sdim // at least fold add of a pointer with an integer into the appropriate 1213249259Sdim // getelementptr. This will improve alias analysis a bit. 1214249259Sdim 1215249259Sdim // Given ((a + b) + c), if (b + c) folds to something interesting, return 1216249259Sdim // (a + (b + c)). 1217249259Sdim if (Instruction::isAssociative(Opcode) && CE1->getOpcode() == Opcode) { 1218249259Sdim Constant *T = ConstantExpr::get(Opcode, CE1->getOperand(1), C2); 1219249259Sdim if (!isa<ConstantExpr>(T) || cast<ConstantExpr>(T)->getOpcode() != Opcode) 1220249259Sdim return ConstantExpr::get(Opcode, CE1->getOperand(0), T); 1221249259Sdim } 1222249259Sdim } else if (isa<ConstantExpr>(C2)) { 1223249259Sdim // If C2 is a constant expr and C1 isn't, flop them around and fold the 1224249259Sdim // other way if possible. 1225249259Sdim if (Instruction::isCommutative(Opcode)) 1226249259Sdim return ConstantFoldBinaryInstruction(Opcode, C2, C1); 1227249259Sdim } 1228249259Sdim 1229249259Sdim // i1 can be simplified in many cases. 1230249259Sdim if (C1->getType()->isIntegerTy(1)) { 1231249259Sdim switch (Opcode) { 1232249259Sdim case Instruction::Add: 1233249259Sdim case Instruction::Sub: 1234249259Sdim return ConstantExpr::getXor(C1, C2); 1235249259Sdim case Instruction::Mul: 1236249259Sdim return ConstantExpr::getAnd(C1, C2); 1237249259Sdim case Instruction::Shl: 1238249259Sdim case Instruction::LShr: 1239249259Sdim case Instruction::AShr: 1240249259Sdim // We can assume that C2 == 0. If it were one the result would be 1241249259Sdim // undefined because the shift value is as large as the bitwidth. 1242249259Sdim return C1; 1243249259Sdim case Instruction::SDiv: 1244249259Sdim case Instruction::UDiv: 1245249259Sdim // We can assume that C2 == 1. If it were zero the result would be 1246249259Sdim // undefined through division by zero. 1247249259Sdim return C1; 1248249259Sdim case Instruction::URem: 1249249259Sdim case Instruction::SRem: 1250249259Sdim // We can assume that C2 == 1. If it were zero the result would be 1251249259Sdim // undefined through division by zero. 1252249259Sdim return ConstantInt::getFalse(C1->getContext()); 1253249259Sdim default: 1254249259Sdim break; 1255249259Sdim } 1256249259Sdim } 1257249259Sdim 1258249259Sdim // We don't know how to fold this. 1259276479Sdim return nullptr; 1260249259Sdim} 1261249259Sdim 1262249259Sdim/// isZeroSizedType - This type is zero sized if its an array or structure of 1263249259Sdim/// zero sized types. The only leaf zero sized type is an empty structure. 1264249259Sdimstatic bool isMaybeZeroSizedType(Type *Ty) { 1265249259Sdim if (StructType *STy = dyn_cast<StructType>(Ty)) { 1266249259Sdim if (STy->isOpaque()) return true; // Can't say. 1267249259Sdim 1268249259Sdim // If all of elements have zero size, this does too. 1269249259Sdim for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) 1270249259Sdim if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; 1271249259Sdim return true; 1272249259Sdim 1273249259Sdim } else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { 1274249259Sdim return isMaybeZeroSizedType(ATy->getElementType()); 1275249259Sdim } 1276249259Sdim return false; 1277249259Sdim} 1278249259Sdim 1279249259Sdim/// IdxCompare - Compare the two constants as though they were getelementptr 1280296417Sdim/// indices. This allows coercion of the types to be the same thing. 1281249259Sdim/// 1282296417Sdim/// If the two constants are the "same" (after coercion), return 0. If the 1283249259Sdim/// first is less than the second, return -1, if the second is less than the 1284249259Sdim/// first, return 1. If the constants are not integral, return -2. 1285249259Sdim/// 1286249259Sdimstatic int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) { 1287249259Sdim if (C1 == C2) return 0; 1288249259Sdim 1289249259Sdim // Ok, we found a different index. If they are not ConstantInt, we can't do 1290249259Sdim // anything with them. 1291249259Sdim if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) 1292249259Sdim return -2; // don't know! 1293249259Sdim 1294288943Sdim // We cannot compare the indices if they don't fit in an int64_t. 1295288943Sdim if (cast<ConstantInt>(C1)->getValue().getActiveBits() > 64 || 1296288943Sdim cast<ConstantInt>(C2)->getValue().getActiveBits() > 64) 1297288943Sdim return -2; // don't know! 1298288943Sdim 1299249259Sdim // Ok, we have two differing integer indices. Sign extend them to be the same 1300288943Sdim // type. 1301288943Sdim int64_t C1Val = cast<ConstantInt>(C1)->getSExtValue(); 1302288943Sdim int64_t C2Val = cast<ConstantInt>(C2)->getSExtValue(); 1303249259Sdim 1304288943Sdim if (C1Val == C2Val) return 0; // They are equal 1305249259Sdim 1306249259Sdim // If the type being indexed over is really just a zero sized type, there is 1307249259Sdim // no pointer difference being made here. 1308249259Sdim if (isMaybeZeroSizedType(ElTy)) 1309249259Sdim return -2; // dunno. 1310249259Sdim 1311249259Sdim // If they are really different, now that they are the same type, then we 1312249259Sdim // found a difference! 1313288943Sdim if (C1Val < C2Val) 1314249259Sdim return -1; 1315249259Sdim else 1316249259Sdim return 1; 1317249259Sdim} 1318249259Sdim 1319249259Sdim/// evaluateFCmpRelation - This function determines if there is anything we can 1320249259Sdim/// decide about the two constants provided. This doesn't need to handle simple 1321249259Sdim/// things like ConstantFP comparisons, but should instead handle ConstantExprs. 1322249259Sdim/// If we can determine that the two constants have a particular relation to 1323249259Sdim/// each other, we should return the corresponding FCmpInst predicate, 1324249259Sdim/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in 1325249259Sdim/// ConstantFoldCompareInstruction. 1326249259Sdim/// 1327249259Sdim/// To simplify this code we canonicalize the relation so that the first 1328249259Sdim/// operand is always the most "complex" of the two. We consider ConstantFP 1329249259Sdim/// to be the simplest, and ConstantExprs to be the most complex. 1330249259Sdimstatic FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) { 1331249259Sdim assert(V1->getType() == V2->getType() && 1332249259Sdim "Cannot compare values of different types!"); 1333249259Sdim 1334249259Sdim // Handle degenerate case quickly 1335249259Sdim if (V1 == V2) return FCmpInst::FCMP_OEQ; 1336249259Sdim 1337249259Sdim if (!isa<ConstantExpr>(V1)) { 1338249259Sdim if (!isa<ConstantExpr>(V2)) { 1339288943Sdim // Simple case, use the standard constant folder. 1340276479Sdim ConstantInt *R = nullptr; 1341249259Sdim R = dyn_cast<ConstantInt>( 1342249259Sdim ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2)); 1343249259Sdim if (R && !R->isZero()) 1344249259Sdim return FCmpInst::FCMP_OEQ; 1345249259Sdim R = dyn_cast<ConstantInt>( 1346249259Sdim ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2)); 1347249259Sdim if (R && !R->isZero()) 1348249259Sdim return FCmpInst::FCMP_OLT; 1349249259Sdim R = dyn_cast<ConstantInt>( 1350249259Sdim ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2)); 1351249259Sdim if (R && !R->isZero()) 1352249259Sdim return FCmpInst::FCMP_OGT; 1353249259Sdim 1354249259Sdim // Nothing more we can do 1355249259Sdim return FCmpInst::BAD_FCMP_PREDICATE; 1356249259Sdim } 1357249259Sdim 1358249259Sdim // If the first operand is simple and second is ConstantExpr, swap operands. 1359249259Sdim FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); 1360249259Sdim if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) 1361249259Sdim return FCmpInst::getSwappedPredicate(SwappedRelation); 1362249259Sdim } else { 1363249259Sdim // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1364249259Sdim // constantexpr or a simple constant. 1365249259Sdim ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1366249259Sdim switch (CE1->getOpcode()) { 1367249259Sdim case Instruction::FPTrunc: 1368249259Sdim case Instruction::FPExt: 1369249259Sdim case Instruction::UIToFP: 1370249259Sdim case Instruction::SIToFP: 1371249259Sdim // We might be able to do something with these but we don't right now. 1372249259Sdim break; 1373249259Sdim default: 1374249259Sdim break; 1375249259Sdim } 1376249259Sdim } 1377249259Sdim // There are MANY other foldings that we could perform here. They will 1378249259Sdim // probably be added on demand, as they seem needed. 1379249259Sdim return FCmpInst::BAD_FCMP_PREDICATE; 1380249259Sdim} 1381249259Sdim 1382276479Sdimstatic ICmpInst::Predicate areGlobalsPotentiallyEqual(const GlobalValue *GV1, 1383276479Sdim const GlobalValue *GV2) { 1384280031Sdim auto isGlobalUnsafeForEquality = [](const GlobalValue *GV) { 1385280031Sdim if (GV->hasExternalWeakLinkage() || GV->hasWeakAnyLinkage()) 1386280031Sdim return true; 1387280031Sdim if (const auto *GVar = dyn_cast<GlobalVariable>(GV)) { 1388288943Sdim Type *Ty = GVar->getValueType(); 1389280031Sdim // A global with opaque type might end up being zero sized. 1390280031Sdim if (!Ty->isSized()) 1391280031Sdim return true; 1392280031Sdim // A global with an empty type might lie at the address of any other 1393280031Sdim // global. 1394280031Sdim if (Ty->isEmptyTy()) 1395280031Sdim return true; 1396280031Sdim } 1397280031Sdim return false; 1398280031Sdim }; 1399276479Sdim // Don't try to decide equality of aliases. 1400276479Sdim if (!isa<GlobalAlias>(GV1) && !isa<GlobalAlias>(GV2)) 1401280031Sdim if (!isGlobalUnsafeForEquality(GV1) && !isGlobalUnsafeForEquality(GV2)) 1402276479Sdim return ICmpInst::ICMP_NE; 1403276479Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1404276479Sdim} 1405276479Sdim 1406249259Sdim/// evaluateICmpRelation - This function determines if there is anything we can 1407249259Sdim/// decide about the two constants provided. This doesn't need to handle simple 1408249259Sdim/// things like integer comparisons, but should instead handle ConstantExprs 1409249259Sdim/// and GlobalValues. If we can determine that the two constants have a 1410249259Sdim/// particular relation to each other, we should return the corresponding ICmp 1411249259Sdim/// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. 1412249259Sdim/// 1413249259Sdim/// To simplify this code we canonicalize the relation so that the first 1414249259Sdim/// operand is always the most "complex" of the two. We consider simple 1415249259Sdim/// constants (like ConstantInt) to be the simplest, followed by 1416249259Sdim/// GlobalValues, followed by ConstantExpr's (the most complex). 1417249259Sdim/// 1418249259Sdimstatic ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, 1419249259Sdim bool isSigned) { 1420249259Sdim assert(V1->getType() == V2->getType() && 1421249259Sdim "Cannot compare different types of values!"); 1422249259Sdim if (V1 == V2) return ICmpInst::ICMP_EQ; 1423249259Sdim 1424249259Sdim if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) && 1425249259Sdim !isa<BlockAddress>(V1)) { 1426249259Sdim if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) && 1427249259Sdim !isa<BlockAddress>(V2)) { 1428249259Sdim // We distilled this down to a simple case, use the standard constant 1429249259Sdim // folder. 1430276479Sdim ConstantInt *R = nullptr; 1431249259Sdim ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; 1432249259Sdim R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1433249259Sdim if (R && !R->isZero()) 1434249259Sdim return pred; 1435249259Sdim pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1436249259Sdim R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1437249259Sdim if (R && !R->isZero()) 1438249259Sdim return pred; 1439249259Sdim pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1440249259Sdim R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); 1441249259Sdim if (R && !R->isZero()) 1442249259Sdim return pred; 1443249259Sdim 1444249259Sdim // If we couldn't figure it out, bail. 1445249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1446249259Sdim } 1447249259Sdim 1448249259Sdim // If the first operand is simple, swap operands. 1449249259Sdim ICmpInst::Predicate SwappedRelation = 1450249259Sdim evaluateICmpRelation(V2, V1, isSigned); 1451249259Sdim if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1452249259Sdim return ICmpInst::getSwappedPredicate(SwappedRelation); 1453249259Sdim 1454249259Sdim } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) { 1455249259Sdim if (isa<ConstantExpr>(V2)) { // Swap as necessary. 1456249259Sdim ICmpInst::Predicate SwappedRelation = 1457249259Sdim evaluateICmpRelation(V2, V1, isSigned); 1458249259Sdim if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1459249259Sdim return ICmpInst::getSwappedPredicate(SwappedRelation); 1460249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1461249259Sdim } 1462249259Sdim 1463249259Sdim // Now we know that the RHS is a GlobalValue, BlockAddress or simple 1464249259Sdim // constant (which, since the types must match, means that it's a 1465249259Sdim // ConstantPointerNull). 1466249259Sdim if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { 1467276479Sdim return areGlobalsPotentiallyEqual(GV, GV2); 1468249259Sdim } else if (isa<BlockAddress>(V2)) { 1469249259Sdim return ICmpInst::ICMP_NE; // Globals never equal labels. 1470249259Sdim } else { 1471249259Sdim assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); 1472249259Sdim // GlobalVals can never be null unless they have external weak linkage. 1473249259Sdim // We don't try to evaluate aliases here. 1474249259Sdim if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV)) 1475249259Sdim return ICmpInst::ICMP_NE; 1476249259Sdim } 1477249259Sdim } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) { 1478249259Sdim if (isa<ConstantExpr>(V2)) { // Swap as necessary. 1479249259Sdim ICmpInst::Predicate SwappedRelation = 1480249259Sdim evaluateICmpRelation(V2, V1, isSigned); 1481249259Sdim if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) 1482249259Sdim return ICmpInst::getSwappedPredicate(SwappedRelation); 1483249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1484249259Sdim } 1485249259Sdim 1486249259Sdim // Now we know that the RHS is a GlobalValue, BlockAddress or simple 1487249259Sdim // constant (which, since the types must match, means that it is a 1488249259Sdim // ConstantPointerNull). 1489249259Sdim if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) { 1490249259Sdim // Block address in another function can't equal this one, but block 1491249259Sdim // addresses in the current function might be the same if blocks are 1492249259Sdim // empty. 1493249259Sdim if (BA2->getFunction() != BA->getFunction()) 1494249259Sdim return ICmpInst::ICMP_NE; 1495249259Sdim } else { 1496249259Sdim // Block addresses aren't null, don't equal the address of globals. 1497249259Sdim assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) && 1498249259Sdim "Canonicalization guarantee!"); 1499249259Sdim return ICmpInst::ICMP_NE; 1500249259Sdim } 1501249259Sdim } else { 1502249259Sdim // Ok, the LHS is known to be a constantexpr. The RHS can be any of a 1503249259Sdim // constantexpr, a global, block address, or a simple constant. 1504249259Sdim ConstantExpr *CE1 = cast<ConstantExpr>(V1); 1505249259Sdim Constant *CE1Op0 = CE1->getOperand(0); 1506249259Sdim 1507249259Sdim switch (CE1->getOpcode()) { 1508249259Sdim case Instruction::Trunc: 1509249259Sdim case Instruction::FPTrunc: 1510249259Sdim case Instruction::FPExt: 1511249259Sdim case Instruction::FPToUI: 1512249259Sdim case Instruction::FPToSI: 1513249259Sdim break; // We can't evaluate floating point casts or truncations. 1514249259Sdim 1515249259Sdim case Instruction::UIToFP: 1516249259Sdim case Instruction::SIToFP: 1517249259Sdim case Instruction::BitCast: 1518249259Sdim case Instruction::ZExt: 1519249259Sdim case Instruction::SExt: 1520249259Sdim // If the cast is not actually changing bits, and the second operand is a 1521249259Sdim // null pointer, do the comparison with the pre-casted value. 1522249259Sdim if (V2->isNullValue() && 1523249259Sdim (CE1->getType()->isPointerTy() || CE1->getType()->isIntegerTy())) { 1524249259Sdim if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; 1525249259Sdim if (CE1->getOpcode() == Instruction::SExt) isSigned = true; 1526249259Sdim return evaluateICmpRelation(CE1Op0, 1527249259Sdim Constant::getNullValue(CE1Op0->getType()), 1528249259Sdim isSigned); 1529249259Sdim } 1530249259Sdim break; 1531249259Sdim 1532276479Sdim case Instruction::GetElementPtr: { 1533276479Sdim GEPOperator *CE1GEP = cast<GEPOperator>(CE1); 1534249259Sdim // Ok, since this is a getelementptr, we know that the constant has a 1535249259Sdim // pointer type. Check the various cases. 1536249259Sdim if (isa<ConstantPointerNull>(V2)) { 1537249259Sdim // If we are comparing a GEP to a null pointer, check to see if the base 1538249259Sdim // of the GEP equals the null pointer. 1539249259Sdim if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1540249259Sdim if (GV->hasExternalWeakLinkage()) 1541249259Sdim // Weak linkage GVals could be zero or not. We're comparing that 1542249259Sdim // to null pointer so its greater-or-equal 1543249259Sdim return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; 1544249259Sdim else 1545249259Sdim // If its not weak linkage, the GVal must have a non-zero address 1546249259Sdim // so the result is greater-than 1547249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1548249259Sdim } else if (isa<ConstantPointerNull>(CE1Op0)) { 1549249259Sdim // If we are indexing from a null pointer, check to see if we have any 1550249259Sdim // non-zero indices. 1551249259Sdim for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) 1552249259Sdim if (!CE1->getOperand(i)->isNullValue()) 1553249259Sdim // Offsetting from null, must not be equal. 1554249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1555249259Sdim // Only zero indexes from null, must still be zero. 1556249259Sdim return ICmpInst::ICMP_EQ; 1557249259Sdim } 1558249259Sdim // Otherwise, we can't really say if the first operand is null or not. 1559249259Sdim } else if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { 1560249259Sdim if (isa<ConstantPointerNull>(CE1Op0)) { 1561249259Sdim if (GV2->hasExternalWeakLinkage()) 1562249259Sdim // Weak linkage GVals could be zero or not. We're comparing it to 1563249259Sdim // a null pointer, so its less-or-equal 1564249259Sdim return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; 1565249259Sdim else 1566249259Sdim // If its not weak linkage, the GVal must have a non-zero address 1567249259Sdim // so the result is less-than 1568249259Sdim return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1569249259Sdim } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { 1570249259Sdim if (GV == GV2) { 1571249259Sdim // If this is a getelementptr of the same global, then it must be 1572249259Sdim // different. Because the types must match, the getelementptr could 1573249259Sdim // only have at most one index, and because we fold getelementptr's 1574249259Sdim // with a single zero index, it must be nonzero. 1575249259Sdim assert(CE1->getNumOperands() == 2 && 1576249259Sdim !CE1->getOperand(1)->isNullValue() && 1577249259Sdim "Surprising getelementptr!"); 1578249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1579249259Sdim } else { 1580276479Sdim if (CE1GEP->hasAllZeroIndices()) 1581276479Sdim return areGlobalsPotentiallyEqual(GV, GV2); 1582249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1583249259Sdim } 1584249259Sdim } 1585249259Sdim } else { 1586249259Sdim ConstantExpr *CE2 = cast<ConstantExpr>(V2); 1587249259Sdim Constant *CE2Op0 = CE2->getOperand(0); 1588249259Sdim 1589249259Sdim // There are MANY other foldings that we could perform here. They will 1590249259Sdim // probably be added on demand, as they seem needed. 1591249259Sdim switch (CE2->getOpcode()) { 1592249259Sdim default: break; 1593249259Sdim case Instruction::GetElementPtr: 1594249259Sdim // By far the most common case to handle is when the base pointers are 1595249259Sdim // obviously to the same global. 1596249259Sdim if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { 1597276479Sdim // Don't know relative ordering, but check for inequality. 1598276479Sdim if (CE1Op0 != CE2Op0) { 1599276479Sdim GEPOperator *CE2GEP = cast<GEPOperator>(CE2); 1600276479Sdim if (CE1GEP->hasAllZeroIndices() && CE2GEP->hasAllZeroIndices()) 1601276479Sdim return areGlobalsPotentiallyEqual(cast<GlobalValue>(CE1Op0), 1602276479Sdim cast<GlobalValue>(CE2Op0)); 1603249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1604276479Sdim } 1605249259Sdim // Ok, we know that both getelementptr instructions are based on the 1606249259Sdim // same global. From this, we can precisely determine the relative 1607249259Sdim // ordering of the resultant pointers. 1608249259Sdim unsigned i = 1; 1609249259Sdim 1610249259Sdim // The logic below assumes that the result of the comparison 1611249259Sdim // can be determined by finding the first index that differs. 1612249259Sdim // This doesn't work if there is over-indexing in any 1613249259Sdim // subsequent indices, so check for that case first. 1614249259Sdim if (!CE1->isGEPWithNoNotionalOverIndexing() || 1615249259Sdim !CE2->isGEPWithNoNotionalOverIndexing()) 1616249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1617249259Sdim 1618249259Sdim // Compare all of the operands the GEP's have in common. 1619249259Sdim gep_type_iterator GTI = gep_type_begin(CE1); 1620249259Sdim for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); 1621249259Sdim ++i, ++GTI) 1622249259Sdim switch (IdxCompare(CE1->getOperand(i), 1623249259Sdim CE2->getOperand(i), GTI.getIndexedType())) { 1624249259Sdim case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; 1625249259Sdim case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; 1626249259Sdim case -2: return ICmpInst::BAD_ICMP_PREDICATE; 1627249259Sdim } 1628249259Sdim 1629249259Sdim // Ok, we ran out of things they have in common. If any leftovers 1630249259Sdim // are non-zero then we have a difference, otherwise we are equal. 1631249259Sdim for (; i < CE1->getNumOperands(); ++i) 1632249259Sdim if (!CE1->getOperand(i)->isNullValue()) { 1633249259Sdim if (isa<ConstantInt>(CE1->getOperand(i))) 1634249259Sdim return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; 1635249259Sdim else 1636249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1637249259Sdim } 1638249259Sdim 1639249259Sdim for (; i < CE2->getNumOperands(); ++i) 1640249259Sdim if (!CE2->getOperand(i)->isNullValue()) { 1641249259Sdim if (isa<ConstantInt>(CE2->getOperand(i))) 1642249259Sdim return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; 1643249259Sdim else 1644249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. 1645249259Sdim } 1646249259Sdim return ICmpInst::ICMP_EQ; 1647249259Sdim } 1648249259Sdim } 1649249259Sdim } 1650276479Sdim } 1651249259Sdim default: 1652249259Sdim break; 1653249259Sdim } 1654249259Sdim } 1655249259Sdim 1656249259Sdim return ICmpInst::BAD_ICMP_PREDICATE; 1657249259Sdim} 1658249259Sdim 1659249259SdimConstant *llvm::ConstantFoldCompareInstruction(unsigned short pred, 1660249259Sdim Constant *C1, Constant *C2) { 1661249259Sdim Type *ResultTy; 1662249259Sdim if (VectorType *VT = dyn_cast<VectorType>(C1->getType())) 1663249259Sdim ResultTy = VectorType::get(Type::getInt1Ty(C1->getContext()), 1664249259Sdim VT->getNumElements()); 1665249259Sdim else 1666249259Sdim ResultTy = Type::getInt1Ty(C1->getContext()); 1667249259Sdim 1668249259Sdim // Fold FCMP_FALSE/FCMP_TRUE unconditionally. 1669249259Sdim if (pred == FCmpInst::FCMP_FALSE) 1670249259Sdim return Constant::getNullValue(ResultTy); 1671249259Sdim 1672249259Sdim if (pred == FCmpInst::FCMP_TRUE) 1673249259Sdim return Constant::getAllOnesValue(ResultTy); 1674249259Sdim 1675249259Sdim // Handle some degenerate cases first 1676249259Sdim if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { 1677288943Sdim CmpInst::Predicate Predicate = CmpInst::Predicate(pred); 1678288943Sdim bool isIntegerPredicate = ICmpInst::isIntPredicate(Predicate); 1679249259Sdim // For EQ and NE, we can always pick a value for the undef to make the 1680249259Sdim // predicate pass or fail, so we can return undef. 1681288943Sdim // Also, if both operands are undef, we can return undef for int comparison. 1682288943Sdim if (ICmpInst::isEquality(Predicate) || (isIntegerPredicate && C1 == C2)) 1683249259Sdim return UndefValue::get(ResultTy); 1684288943Sdim 1685288943Sdim // Otherwise, for integer compare, pick the same value as the non-undef 1686288943Sdim // operand, and fold it to true or false. 1687288943Sdim if (isIntegerPredicate) 1688296417Sdim return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(Predicate)); 1689288943Sdim 1690288943Sdim // Choosing NaN for the undef will always make unordered comparison succeed 1691288943Sdim // and ordered comparison fails. 1692288943Sdim return ConstantInt::get(ResultTy, CmpInst::isUnordered(Predicate)); 1693249259Sdim } 1694249259Sdim 1695249259Sdim // icmp eq/ne(null,GV) -> false/true 1696249259Sdim if (C1->isNullValue()) { 1697249259Sdim if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) 1698249259Sdim // Don't try to evaluate aliases. External weak GV can be null. 1699249259Sdim if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1700249259Sdim if (pred == ICmpInst::ICMP_EQ) 1701249259Sdim return ConstantInt::getFalse(C1->getContext()); 1702249259Sdim else if (pred == ICmpInst::ICMP_NE) 1703249259Sdim return ConstantInt::getTrue(C1->getContext()); 1704249259Sdim } 1705249259Sdim // icmp eq/ne(GV,null) -> false/true 1706249259Sdim } else if (C2->isNullValue()) { 1707249259Sdim if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) 1708249259Sdim // Don't try to evaluate aliases. External weak GV can be null. 1709249259Sdim if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { 1710249259Sdim if (pred == ICmpInst::ICMP_EQ) 1711249259Sdim return ConstantInt::getFalse(C1->getContext()); 1712249259Sdim else if (pred == ICmpInst::ICMP_NE) 1713249259Sdim return ConstantInt::getTrue(C1->getContext()); 1714249259Sdim } 1715249259Sdim } 1716249259Sdim 1717249259Sdim // If the comparison is a comparison between two i1's, simplify it. 1718249259Sdim if (C1->getType()->isIntegerTy(1)) { 1719249259Sdim switch(pred) { 1720249259Sdim case ICmpInst::ICMP_EQ: 1721249259Sdim if (isa<ConstantInt>(C2)) 1722249259Sdim return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2)); 1723249259Sdim return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2); 1724249259Sdim case ICmpInst::ICMP_NE: 1725249259Sdim return ConstantExpr::getXor(C1, C2); 1726249259Sdim default: 1727249259Sdim break; 1728249259Sdim } 1729249259Sdim } 1730249259Sdim 1731249259Sdim if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { 1732249259Sdim APInt V1 = cast<ConstantInt>(C1)->getValue(); 1733249259Sdim APInt V2 = cast<ConstantInt>(C2)->getValue(); 1734249259Sdim switch (pred) { 1735249259Sdim default: llvm_unreachable("Invalid ICmp Predicate"); 1736249259Sdim case ICmpInst::ICMP_EQ: return ConstantInt::get(ResultTy, V1 == V2); 1737249259Sdim case ICmpInst::ICMP_NE: return ConstantInt::get(ResultTy, V1 != V2); 1738249259Sdim case ICmpInst::ICMP_SLT: return ConstantInt::get(ResultTy, V1.slt(V2)); 1739249259Sdim case ICmpInst::ICMP_SGT: return ConstantInt::get(ResultTy, V1.sgt(V2)); 1740249259Sdim case ICmpInst::ICMP_SLE: return ConstantInt::get(ResultTy, V1.sle(V2)); 1741249259Sdim case ICmpInst::ICMP_SGE: return ConstantInt::get(ResultTy, V1.sge(V2)); 1742249259Sdim case ICmpInst::ICMP_ULT: return ConstantInt::get(ResultTy, V1.ult(V2)); 1743249259Sdim case ICmpInst::ICMP_UGT: return ConstantInt::get(ResultTy, V1.ugt(V2)); 1744249259Sdim case ICmpInst::ICMP_ULE: return ConstantInt::get(ResultTy, V1.ule(V2)); 1745249259Sdim case ICmpInst::ICMP_UGE: return ConstantInt::get(ResultTy, V1.uge(V2)); 1746249259Sdim } 1747249259Sdim } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { 1748249259Sdim APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); 1749249259Sdim APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); 1750249259Sdim APFloat::cmpResult R = C1V.compare(C2V); 1751249259Sdim switch (pred) { 1752249259Sdim default: llvm_unreachable("Invalid FCmp Predicate"); 1753249259Sdim case FCmpInst::FCMP_FALSE: return Constant::getNullValue(ResultTy); 1754249259Sdim case FCmpInst::FCMP_TRUE: return Constant::getAllOnesValue(ResultTy); 1755249259Sdim case FCmpInst::FCMP_UNO: 1756249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered); 1757249259Sdim case FCmpInst::FCMP_ORD: 1758249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpUnordered); 1759249259Sdim case FCmpInst::FCMP_UEQ: 1760249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1761249259Sdim R==APFloat::cmpEqual); 1762249259Sdim case FCmpInst::FCMP_OEQ: 1763249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpEqual); 1764249259Sdim case FCmpInst::FCMP_UNE: 1765249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpEqual); 1766249259Sdim case FCmpInst::FCMP_ONE: 1767249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || 1768249259Sdim R==APFloat::cmpGreaterThan); 1769249259Sdim case FCmpInst::FCMP_ULT: 1770249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1771249259Sdim R==APFloat::cmpLessThan); 1772249259Sdim case FCmpInst::FCMP_OLT: 1773249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan); 1774249259Sdim case FCmpInst::FCMP_UGT: 1775249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || 1776249259Sdim R==APFloat::cmpGreaterThan); 1777249259Sdim case FCmpInst::FCMP_OGT: 1778249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan); 1779249259Sdim case FCmpInst::FCMP_ULE: 1780249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpGreaterThan); 1781249259Sdim case FCmpInst::FCMP_OLE: 1782249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || 1783249259Sdim R==APFloat::cmpEqual); 1784249259Sdim case FCmpInst::FCMP_UGE: 1785249259Sdim return ConstantInt::get(ResultTy, R!=APFloat::cmpLessThan); 1786249259Sdim case FCmpInst::FCMP_OGE: 1787249259Sdim return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan || 1788249259Sdim R==APFloat::cmpEqual); 1789249259Sdim } 1790249259Sdim } else if (C1->getType()->isVectorTy()) { 1791249259Sdim // If we can constant fold the comparison of each element, constant fold 1792249259Sdim // the whole vector comparison. 1793249259Sdim SmallVector<Constant*, 4> ResElts; 1794249259Sdim Type *Ty = IntegerType::get(C1->getContext(), 32); 1795249259Sdim // Compare the elements, producing an i1 result or constant expr. 1796249259Sdim for (unsigned i = 0, e = C1->getType()->getVectorNumElements(); i != e;++i){ 1797249259Sdim Constant *C1E = 1798249259Sdim ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, i)); 1799249259Sdim Constant *C2E = 1800249259Sdim ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, i)); 1801249259Sdim 1802249259Sdim ResElts.push_back(ConstantExpr::getCompare(pred, C1E, C2E)); 1803249259Sdim } 1804249259Sdim 1805249259Sdim return ConstantVector::get(ResElts); 1806249259Sdim } 1807249259Sdim 1808288943Sdim if (C1->getType()->isFloatingPointTy() && 1809288943Sdim // Only call evaluateFCmpRelation if we have a constant expr to avoid 1810288943Sdim // infinite recursive loop 1811288943Sdim (isa<ConstantExpr>(C1) || isa<ConstantExpr>(C2))) { 1812249259Sdim int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1813249259Sdim switch (evaluateFCmpRelation(C1, C2)) { 1814249259Sdim default: llvm_unreachable("Unknown relation!"); 1815249259Sdim case FCmpInst::FCMP_UNO: 1816249259Sdim case FCmpInst::FCMP_ORD: 1817249259Sdim case FCmpInst::FCMP_UEQ: 1818249259Sdim case FCmpInst::FCMP_UNE: 1819249259Sdim case FCmpInst::FCMP_ULT: 1820249259Sdim case FCmpInst::FCMP_UGT: 1821249259Sdim case FCmpInst::FCMP_ULE: 1822249259Sdim case FCmpInst::FCMP_UGE: 1823249259Sdim case FCmpInst::FCMP_TRUE: 1824249259Sdim case FCmpInst::FCMP_FALSE: 1825249259Sdim case FCmpInst::BAD_FCMP_PREDICATE: 1826249259Sdim break; // Couldn't determine anything about these constants. 1827249259Sdim case FCmpInst::FCMP_OEQ: // We know that C1 == C2 1828249259Sdim Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || 1829249259Sdim pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || 1830249259Sdim pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1831249259Sdim break; 1832249259Sdim case FCmpInst::FCMP_OLT: // We know that C1 < C2 1833249259Sdim Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1834249259Sdim pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || 1835249259Sdim pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); 1836249259Sdim break; 1837249259Sdim case FCmpInst::FCMP_OGT: // We know that C1 > C2 1838249259Sdim Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || 1839249259Sdim pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || 1840249259Sdim pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); 1841249259Sdim break; 1842249259Sdim case FCmpInst::FCMP_OLE: // We know that C1 <= C2 1843249259Sdim // We can only partially decide this relation. 1844249259Sdim if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1845249259Sdim Result = 0; 1846249259Sdim else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1847249259Sdim Result = 1; 1848249259Sdim break; 1849249259Sdim case FCmpInst::FCMP_OGE: // We known that C1 >= C2 1850249259Sdim // We can only partially decide this relation. 1851249259Sdim if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) 1852249259Sdim Result = 0; 1853249259Sdim else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) 1854249259Sdim Result = 1; 1855249259Sdim break; 1856249259Sdim case FCmpInst::FCMP_ONE: // We know that C1 != C2 1857249259Sdim // We can only partially decide this relation. 1858249259Sdim if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) 1859249259Sdim Result = 0; 1860249259Sdim else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) 1861249259Sdim Result = 1; 1862249259Sdim break; 1863249259Sdim } 1864249259Sdim 1865249259Sdim // If we evaluated the result, return it now. 1866249259Sdim if (Result != -1) 1867249259Sdim return ConstantInt::get(ResultTy, Result); 1868249259Sdim 1869249259Sdim } else { 1870249259Sdim // Evaluate the relation between the two constants, per the predicate. 1871249259Sdim int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. 1872296417Sdim switch (evaluateICmpRelation(C1, C2, 1873296417Sdim CmpInst::isSigned((CmpInst::Predicate)pred))) { 1874249259Sdim default: llvm_unreachable("Unknown relational!"); 1875249259Sdim case ICmpInst::BAD_ICMP_PREDICATE: 1876249259Sdim break; // Couldn't determine anything about these constants. 1877249259Sdim case ICmpInst::ICMP_EQ: // We know the constants are equal! 1878249259Sdim // If we know the constants are equal, we can decide the result of this 1879249259Sdim // computation precisely. 1880249259Sdim Result = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred); 1881249259Sdim break; 1882249259Sdim case ICmpInst::ICMP_ULT: 1883249259Sdim switch (pred) { 1884249259Sdim case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE: 1885249259Sdim Result = 1; break; 1886249259Sdim case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE: 1887249259Sdim Result = 0; break; 1888249259Sdim } 1889249259Sdim break; 1890249259Sdim case ICmpInst::ICMP_SLT: 1891249259Sdim switch (pred) { 1892249259Sdim case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE: 1893249259Sdim Result = 1; break; 1894249259Sdim case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE: 1895249259Sdim Result = 0; break; 1896249259Sdim } 1897249259Sdim break; 1898249259Sdim case ICmpInst::ICMP_UGT: 1899249259Sdim switch (pred) { 1900249259Sdim case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE: 1901249259Sdim Result = 1; break; 1902249259Sdim case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE: 1903249259Sdim Result = 0; break; 1904249259Sdim } 1905249259Sdim break; 1906249259Sdim case ICmpInst::ICMP_SGT: 1907249259Sdim switch (pred) { 1908249259Sdim case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE: 1909249259Sdim Result = 1; break; 1910249259Sdim case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE: 1911249259Sdim Result = 0; break; 1912249259Sdim } 1913249259Sdim break; 1914249259Sdim case ICmpInst::ICMP_ULE: 1915249259Sdim if (pred == ICmpInst::ICMP_UGT) Result = 0; 1916249259Sdim if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1; 1917249259Sdim break; 1918249259Sdim case ICmpInst::ICMP_SLE: 1919249259Sdim if (pred == ICmpInst::ICMP_SGT) Result = 0; 1920249259Sdim if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1; 1921249259Sdim break; 1922249259Sdim case ICmpInst::ICMP_UGE: 1923249259Sdim if (pred == ICmpInst::ICMP_ULT) Result = 0; 1924249259Sdim if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1; 1925249259Sdim break; 1926249259Sdim case ICmpInst::ICMP_SGE: 1927249259Sdim if (pred == ICmpInst::ICMP_SLT) Result = 0; 1928249259Sdim if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1; 1929249259Sdim break; 1930249259Sdim case ICmpInst::ICMP_NE: 1931249259Sdim if (pred == ICmpInst::ICMP_EQ) Result = 0; 1932249259Sdim if (pred == ICmpInst::ICMP_NE) Result = 1; 1933249259Sdim break; 1934249259Sdim } 1935249259Sdim 1936249259Sdim // If we evaluated the result, return it now. 1937249259Sdim if (Result != -1) 1938249259Sdim return ConstantInt::get(ResultTy, Result); 1939249259Sdim 1940249259Sdim // If the right hand side is a bitcast, try using its inverse to simplify 1941249259Sdim // it by moving it to the left hand side. We can't do this if it would turn 1942249259Sdim // a vector compare into a scalar compare or visa versa. 1943249259Sdim if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) { 1944249259Sdim Constant *CE2Op0 = CE2->getOperand(0); 1945249259Sdim if (CE2->getOpcode() == Instruction::BitCast && 1946249259Sdim CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy()) { 1947249259Sdim Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType()); 1948249259Sdim return ConstantExpr::getICmp(pred, Inverse, CE2Op0); 1949249259Sdim } 1950249259Sdim } 1951249259Sdim 1952249259Sdim // If the left hand side is an extension, try eliminating it. 1953249259Sdim if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { 1954296417Sdim if ((CE1->getOpcode() == Instruction::SExt && 1955296417Sdim ICmpInst::isSigned((ICmpInst::Predicate)pred)) || 1956296417Sdim (CE1->getOpcode() == Instruction::ZExt && 1957296417Sdim !ICmpInst::isSigned((ICmpInst::Predicate)pred))){ 1958249259Sdim Constant *CE1Op0 = CE1->getOperand(0); 1959249259Sdim Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType()); 1960249259Sdim if (CE1Inverse == CE1Op0) { 1961249259Sdim // Check whether we can safely truncate the right hand side. 1962249259Sdim Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType()); 1963261991Sdim if (ConstantExpr::getCast(CE1->getOpcode(), C2Inverse, 1964261991Sdim C2->getType()) == C2) 1965249259Sdim return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse); 1966249259Sdim } 1967249259Sdim } 1968249259Sdim } 1969249259Sdim 1970249259Sdim if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) || 1971249259Sdim (C1->isNullValue() && !C2->isNullValue())) { 1972249259Sdim // If C2 is a constant expr and C1 isn't, flip them around and fold the 1973249259Sdim // other way if possible. 1974249259Sdim // Also, if C1 is null and C2 isn't, flip them around. 1975249259Sdim pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); 1976249259Sdim return ConstantExpr::getICmp(pred, C2, C1); 1977249259Sdim } 1978249259Sdim } 1979276479Sdim return nullptr; 1980249259Sdim} 1981249259Sdim 1982249259Sdim/// isInBoundsIndices - Test whether the given sequence of *normalized* indices 1983249259Sdim/// is "inbounds". 1984249259Sdimtemplate<typename IndexTy> 1985249259Sdimstatic bool isInBoundsIndices(ArrayRef<IndexTy> Idxs) { 1986249259Sdim // No indices means nothing that could be out of bounds. 1987249259Sdim if (Idxs.empty()) return true; 1988249259Sdim 1989249259Sdim // If the first index is zero, it's in bounds. 1990249259Sdim if (cast<Constant>(Idxs[0])->isNullValue()) return true; 1991249259Sdim 1992249259Sdim // If the first index is one and all the rest are zero, it's in bounds, 1993249259Sdim // by the one-past-the-end rule. 1994249259Sdim if (!cast<ConstantInt>(Idxs[0])->isOne()) 1995249259Sdim return false; 1996249259Sdim for (unsigned i = 1, e = Idxs.size(); i != e; ++i) 1997249259Sdim if (!cast<Constant>(Idxs[i])->isNullValue()) 1998249259Sdim return false; 1999249259Sdim return true; 2000249259Sdim} 2001249259Sdim 2002261991Sdim/// \brief Test whether a given ConstantInt is in-range for a SequentialType. 2003296417Sdimstatic bool isIndexInRangeOfSequentialType(SequentialType *STy, 2004261991Sdim const ConstantInt *CI) { 2005296417Sdim // And indices are valid when indexing along a pointer 2006296417Sdim if (isa<PointerType>(STy)) 2007296417Sdim return true; 2008261991Sdim 2009261991Sdim uint64_t NumElements = 0; 2010261991Sdim // Determine the number of elements in our sequential type. 2011296417Sdim if (auto *ATy = dyn_cast<ArrayType>(STy)) 2012261991Sdim NumElements = ATy->getNumElements(); 2013296417Sdim else if (auto *VTy = dyn_cast<VectorType>(STy)) 2014261991Sdim NumElements = VTy->getNumElements(); 2015261991Sdim 2016261991Sdim assert((isa<ArrayType>(STy) || NumElements > 0) && 2017261991Sdim "didn't expect non-array type to have zero elements!"); 2018261991Sdim 2019261991Sdim // We cannot bounds check the index if it doesn't fit in an int64_t. 2020261991Sdim if (CI->getValue().getActiveBits() > 64) 2021261991Sdim return false; 2022261991Sdim 2023261991Sdim // A negative index or an index past the end of our sequential type is 2024261991Sdim // considered out-of-range. 2025261991Sdim int64_t IndexVal = CI->getSExtValue(); 2026261991Sdim if (IndexVal < 0 || (NumElements > 0 && (uint64_t)IndexVal >= NumElements)) 2027261991Sdim return false; 2028261991Sdim 2029261991Sdim // Otherwise, it is in-range. 2030261991Sdim return true; 2031261991Sdim} 2032261991Sdim 2033249259Sdimtemplate<typename IndexTy> 2034288943Sdimstatic Constant *ConstantFoldGetElementPtrImpl(Type *PointeeTy, Constant *C, 2035249259Sdim bool inBounds, 2036249259Sdim ArrayRef<IndexTy> Idxs) { 2037249259Sdim if (Idxs.empty()) return C; 2038249259Sdim Constant *Idx0 = cast<Constant>(Idxs[0]); 2039249259Sdim if ((Idxs.size() == 1 && Idx0->isNullValue())) 2040249259Sdim return C; 2041249259Sdim 2042249259Sdim if (isa<UndefValue>(C)) { 2043249259Sdim PointerType *Ptr = cast<PointerType>(C->getType()); 2044288943Sdim Type *Ty = GetElementPtrInst::getIndexedType( 2045288943Sdim cast<PointerType>(Ptr->getScalarType())->getElementType(), Idxs); 2046276479Sdim assert(Ty && "Invalid indices for GEP!"); 2047249259Sdim return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); 2048249259Sdim } 2049249259Sdim 2050249259Sdim if (C->isNullValue()) { 2051249259Sdim bool isNull = true; 2052249259Sdim for (unsigned i = 0, e = Idxs.size(); i != e; ++i) 2053249259Sdim if (!cast<Constant>(Idxs[i])->isNullValue()) { 2054249259Sdim isNull = false; 2055249259Sdim break; 2056249259Sdim } 2057249259Sdim if (isNull) { 2058249259Sdim PointerType *Ptr = cast<PointerType>(C->getType()); 2059288943Sdim Type *Ty = GetElementPtrInst::getIndexedType( 2060288943Sdim cast<PointerType>(Ptr->getScalarType())->getElementType(), Idxs); 2061276479Sdim assert(Ty && "Invalid indices for GEP!"); 2062249259Sdim return ConstantPointerNull::get(PointerType::get(Ty, 2063249259Sdim Ptr->getAddressSpace())); 2064249259Sdim } 2065249259Sdim } 2066249259Sdim 2067249259Sdim if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { 2068249259Sdim // Combine Indices - If the source pointer to this getelementptr instruction 2069249259Sdim // is a getelementptr instruction, combine the indices of the two 2070249259Sdim // getelementptr instructions into a single instruction. 2071249259Sdim // 2072249259Sdim if (CE->getOpcode() == Instruction::GetElementPtr) { 2073276479Sdim Type *LastTy = nullptr; 2074249259Sdim for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); 2075249259Sdim I != E; ++I) 2076249259Sdim LastTy = *I; 2077249259Sdim 2078261991Sdim // We cannot combine indices if doing so would take us outside of an 2079261991Sdim // array or vector. Doing otherwise could trick us if we evaluated such a 2080261991Sdim // GEP as part of a load. 2081261991Sdim // 2082261991Sdim // e.g. Consider if the original GEP was: 2083261991Sdim // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c, 2084261991Sdim // i32 0, i32 0, i64 0) 2085261991Sdim // 2086261991Sdim // If we then tried to offset it by '8' to get to the third element, 2087261991Sdim // an i8, we should *not* get: 2088261991Sdim // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c, 2089261991Sdim // i32 0, i32 0, i64 8) 2090261991Sdim // 2091261991Sdim // This GEP tries to index array element '8 which runs out-of-bounds. 2092261991Sdim // Subsequent evaluation would get confused and produce erroneous results. 2093261991Sdim // 2094261991Sdim // The following prohibits such a GEP from being formed by checking to see 2095261991Sdim // if the index is in-range with respect to an array or vector. 2096261991Sdim bool PerformFold = false; 2097261991Sdim if (Idx0->isNullValue()) 2098261991Sdim PerformFold = true; 2099261991Sdim else if (SequentialType *STy = dyn_cast_or_null<SequentialType>(LastTy)) 2100261991Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx0)) 2101261991Sdim PerformFold = isIndexInRangeOfSequentialType(STy, CI); 2102261991Sdim 2103261991Sdim if (PerformFold) { 2104249259Sdim SmallVector<Value*, 16> NewIndices; 2105249259Sdim NewIndices.reserve(Idxs.size() + CE->getNumOperands()); 2106288943Sdim NewIndices.append(CE->op_begin() + 1, CE->op_end() - 1); 2107249259Sdim 2108249259Sdim // Add the last index of the source with the first index of the new GEP. 2109249259Sdim // Make sure to handle the case when they are actually different types. 2110249259Sdim Constant *Combined = CE->getOperand(CE->getNumOperands()-1); 2111249259Sdim // Otherwise it must be an array. 2112249259Sdim if (!Idx0->isNullValue()) { 2113249259Sdim Type *IdxTy = Combined->getType(); 2114249259Sdim if (IdxTy != Idx0->getType()) { 2115288943Sdim unsigned CommonExtendedWidth = 2116288943Sdim std::max(IdxTy->getIntegerBitWidth(), 2117288943Sdim Idx0->getType()->getIntegerBitWidth()); 2118288943Sdim CommonExtendedWidth = std::max(CommonExtendedWidth, 64U); 2119288943Sdim 2120288943Sdim Type *CommonTy = 2121288943Sdim Type::getIntNTy(IdxTy->getContext(), CommonExtendedWidth); 2122288943Sdim Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, CommonTy); 2123288943Sdim Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, CommonTy); 2124249259Sdim Combined = ConstantExpr::get(Instruction::Add, C1, C2); 2125249259Sdim } else { 2126249259Sdim Combined = 2127249259Sdim ConstantExpr::get(Instruction::Add, Idx0, Combined); 2128249259Sdim } 2129249259Sdim } 2130249259Sdim 2131249259Sdim NewIndices.push_back(Combined); 2132249259Sdim NewIndices.append(Idxs.begin() + 1, Idxs.end()); 2133288943Sdim return ConstantExpr::getGetElementPtr( 2134288943Sdim cast<GEPOperator>(CE)->getSourceElementType(), CE->getOperand(0), 2135288943Sdim NewIndices, inBounds && cast<GEPOperator>(CE)->isInBounds()); 2136249259Sdim } 2137249259Sdim } 2138249259Sdim 2139249259Sdim // Attempt to fold casts to the same type away. For example, folding: 2140249259Sdim // 2141249259Sdim // i32* getelementptr ([2 x i32]* bitcast ([3 x i32]* %X to [2 x i32]*), 2142249259Sdim // i64 0, i64 0) 2143249259Sdim // into: 2144249259Sdim // 2145249259Sdim // i32* getelementptr ([3 x i32]* %X, i64 0, i64 0) 2146249259Sdim // 2147249259Sdim // Don't fold if the cast is changing address spaces. 2148249259Sdim if (CE->isCast() && Idxs.size() > 1 && Idx0->isNullValue()) { 2149249259Sdim PointerType *SrcPtrTy = 2150249259Sdim dyn_cast<PointerType>(CE->getOperand(0)->getType()); 2151249259Sdim PointerType *DstPtrTy = dyn_cast<PointerType>(CE->getType()); 2152249259Sdim if (SrcPtrTy && DstPtrTy) { 2153249259Sdim ArrayType *SrcArrayTy = 2154249259Sdim dyn_cast<ArrayType>(SrcPtrTy->getElementType()); 2155249259Sdim ArrayType *DstArrayTy = 2156249259Sdim dyn_cast<ArrayType>(DstPtrTy->getElementType()); 2157249259Sdim if (SrcArrayTy && DstArrayTy 2158249259Sdim && SrcArrayTy->getElementType() == DstArrayTy->getElementType() 2159249259Sdim && SrcPtrTy->getAddressSpace() == DstPtrTy->getAddressSpace()) 2160288943Sdim return ConstantExpr::getGetElementPtr( 2161288943Sdim SrcArrayTy, (Constant *)CE->getOperand(0), Idxs, inBounds); 2162249259Sdim } 2163249259Sdim } 2164249259Sdim } 2165249259Sdim 2166249259Sdim // Check to see if any array indices are not within the corresponding 2167261991Sdim // notional array or vector bounds. If so, try to determine if they can be 2168261991Sdim // factored out into preceding dimensions. 2169249259Sdim SmallVector<Constant *, 8> NewIdxs; 2170288943Sdim Type *Ty = PointeeTy; 2171288943Sdim Type *Prev = C->getType(); 2172288943Sdim bool Unknown = !isa<ConstantInt>(Idxs[0]); 2173288943Sdim for (unsigned i = 1, e = Idxs.size(); i != e; 2174249259Sdim Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) { 2175249259Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) { 2176261991Sdim if (isa<ArrayType>(Ty) || isa<VectorType>(Ty)) 2177261991Sdim if (CI->getSExtValue() > 0 && 2178261991Sdim !isIndexInRangeOfSequentialType(cast<SequentialType>(Ty), CI)) { 2179249259Sdim if (isa<SequentialType>(Prev)) { 2180249259Sdim // It's out of range, but we can factor it into the prior 2181249259Sdim // dimension. 2182249259Sdim NewIdxs.resize(Idxs.size()); 2183261991Sdim uint64_t NumElements = 0; 2184296417Sdim if (auto *ATy = dyn_cast<ArrayType>(Ty)) 2185261991Sdim NumElements = ATy->getNumElements(); 2186261991Sdim else 2187261991Sdim NumElements = cast<VectorType>(Ty)->getNumElements(); 2188261991Sdim 2189261991Sdim ConstantInt *Factor = ConstantInt::get(CI->getType(), NumElements); 2190249259Sdim NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); 2191249259Sdim 2192249259Sdim Constant *PrevIdx = cast<Constant>(Idxs[i-1]); 2193249259Sdim Constant *Div = ConstantExpr::getSDiv(CI, Factor); 2194249259Sdim 2195288943Sdim unsigned CommonExtendedWidth = 2196288943Sdim std::max(PrevIdx->getType()->getIntegerBitWidth(), 2197288943Sdim Div->getType()->getIntegerBitWidth()); 2198288943Sdim CommonExtendedWidth = std::max(CommonExtendedWidth, 64U); 2199288943Sdim 2200249259Sdim // Before adding, extend both operands to i64 to avoid 2201249259Sdim // overflow trouble. 2202288943Sdim if (!PrevIdx->getType()->isIntegerTy(CommonExtendedWidth)) 2203288943Sdim PrevIdx = ConstantExpr::getSExt( 2204288943Sdim PrevIdx, 2205288943Sdim Type::getIntNTy(Div->getContext(), CommonExtendedWidth)); 2206288943Sdim if (!Div->getType()->isIntegerTy(CommonExtendedWidth)) 2207288943Sdim Div = ConstantExpr::getSExt( 2208288943Sdim Div, Type::getIntNTy(Div->getContext(), CommonExtendedWidth)); 2209249259Sdim 2210249259Sdim NewIdxs[i-1] = ConstantExpr::getAdd(PrevIdx, Div); 2211249259Sdim } else { 2212249259Sdim // It's out of range, but the prior dimension is a struct 2213249259Sdim // so we can't do anything about it. 2214249259Sdim Unknown = true; 2215249259Sdim } 2216249259Sdim } 2217249259Sdim } else { 2218249259Sdim // We don't know if it's in range or not. 2219249259Sdim Unknown = true; 2220249259Sdim } 2221249259Sdim } 2222249259Sdim 2223249259Sdim // If we did any factoring, start over with the adjusted indices. 2224249259Sdim if (!NewIdxs.empty()) { 2225249259Sdim for (unsigned i = 0, e = Idxs.size(); i != e; ++i) 2226249259Sdim if (!NewIdxs[i]) NewIdxs[i] = cast<Constant>(Idxs[i]); 2227288943Sdim return ConstantExpr::getGetElementPtr(PointeeTy, C, NewIdxs, inBounds); 2228249259Sdim } 2229249259Sdim 2230249259Sdim // If all indices are known integers and normalized, we can do a simple 2231249259Sdim // check for the "inbounds" property. 2232280031Sdim if (!Unknown && !inBounds) 2233280031Sdim if (auto *GV = dyn_cast<GlobalVariable>(C)) 2234280031Sdim if (!GV->hasExternalWeakLinkage() && isInBoundsIndices(Idxs)) 2235288943Sdim return ConstantExpr::getInBoundsGetElementPtr(PointeeTy, C, Idxs); 2236249259Sdim 2237276479Sdim return nullptr; 2238249259Sdim} 2239249259Sdim 2240249259SdimConstant *llvm::ConstantFoldGetElementPtr(Constant *C, 2241249259Sdim bool inBounds, 2242249259Sdim ArrayRef<Constant *> Idxs) { 2243288943Sdim return ConstantFoldGetElementPtrImpl( 2244288943Sdim cast<PointerType>(C->getType()->getScalarType())->getElementType(), C, 2245288943Sdim inBounds, Idxs); 2246249259Sdim} 2247249259Sdim 2248249259SdimConstant *llvm::ConstantFoldGetElementPtr(Constant *C, 2249249259Sdim bool inBounds, 2250249259Sdim ArrayRef<Value *> Idxs) { 2251288943Sdim return ConstantFoldGetElementPtrImpl( 2252288943Sdim cast<PointerType>(C->getType()->getScalarType())->getElementType(), C, 2253288943Sdim inBounds, Idxs); 2254249259Sdim} 2255288943Sdim 2256288943SdimConstant *llvm::ConstantFoldGetElementPtr(Type *Ty, Constant *C, 2257288943Sdim bool inBounds, 2258288943Sdim ArrayRef<Constant *> Idxs) { 2259288943Sdim return ConstantFoldGetElementPtrImpl(Ty, C, inBounds, Idxs); 2260288943Sdim} 2261288943Sdim 2262288943SdimConstant *llvm::ConstantFoldGetElementPtr(Type *Ty, Constant *C, 2263288943Sdim bool inBounds, 2264288943Sdim ArrayRef<Value *> Idxs) { 2265288943Sdim return ConstantFoldGetElementPtrImpl(Ty, C, inBounds, Idxs); 2266288943Sdim} 2267