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Diffstat (limited to 'lib/VMCore/ConstantFold.cpp')
| -rw-r--r-- | lib/VMCore/ConstantFold.cpp | 2066 |
1 files changed, 0 insertions, 2066 deletions
diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp deleted file mode 100644 index fe3edac..0000000 --- a/lib/VMCore/ConstantFold.cpp +++ /dev/null @@ -1,2066 +0,0 @@ -//===- ConstantFold.cpp - LLVM constant folder ----------------------------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This file implements folding of constants for LLVM. This implements the -// (internal) ConstantFold.h interface, which is used by the -// ConstantExpr::get* methods to automatically fold constants when possible. -// -// The current constant folding implementation is implemented in two pieces: the -// pieces that don't need DataLayout, and the pieces that do. This is to avoid -// a dependence in VMCore on Target. -// -//===----------------------------------------------------------------------===// - -#include "ConstantFold.h" -#include "llvm/Constants.h" -#include "llvm/Instructions.h" -#include "llvm/DerivedTypes.h" -#include "llvm/Function.h" -#include "llvm/GlobalAlias.h" -#include "llvm/GlobalVariable.h" -#include "llvm/Operator.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/Support/Compiler.h" -#include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/GetElementPtrTypeIterator.h" -#include "llvm/Support/ManagedStatic.h" -#include "llvm/Support/MathExtras.h" -#include <limits> -using namespace llvm; - -//===----------------------------------------------------------------------===// -// ConstantFold*Instruction Implementations -//===----------------------------------------------------------------------===// - -/// BitCastConstantVector - Convert the specified vector Constant node to the -/// specified vector type. At this point, we know that the elements of the -/// input vector constant are all simple integer or FP values. -static Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) { - - if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy); - if (CV->isNullValue()) return Constant::getNullValue(DstTy); - - // If this cast changes element count then we can't handle it here: - // doing so requires endianness information. This should be handled by - // Analysis/ConstantFolding.cpp - unsigned NumElts = DstTy->getNumElements(); - if (NumElts != CV->getType()->getVectorNumElements()) - return 0; - - Type *DstEltTy = DstTy->getElementType(); - - SmallVector<Constant*, 16> Result; - Type *Ty = IntegerType::get(CV->getContext(), 32); - for (unsigned i = 0; i != NumElts; ++i) { - Constant *C = - ConstantExpr::getExtractElement(CV, ConstantInt::get(Ty, i)); - C = ConstantExpr::getBitCast(C, DstEltTy); - Result.push_back(C); - } - - return ConstantVector::get(Result); -} - -/// This function determines which opcode to use to fold two constant cast -/// expressions together. It uses CastInst::isEliminableCastPair to determine -/// the opcode. Consequently its just a wrapper around that function. -/// @brief Determine if it is valid to fold a cast of a cast -static unsigned -foldConstantCastPair( - unsigned opc, ///< opcode of the second cast constant expression - ConstantExpr *Op, ///< the first cast constant expression - Type *DstTy ///< desintation type of the first cast -) { - assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!"); - assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type"); - assert(CastInst::isCast(opc) && "Invalid cast opcode"); - - // The the types and opcodes for the two Cast constant expressions - Type *SrcTy = Op->getOperand(0)->getType(); - Type *MidTy = Op->getType(); - Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode()); - Instruction::CastOps secondOp = Instruction::CastOps(opc); - - // Assume that pointers are never more than 64 bits wide. - IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext()); - - // Let CastInst::isEliminableCastPair do the heavy lifting. - return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy, - FakeIntPtrTy, FakeIntPtrTy, - FakeIntPtrTy); -} - -static Constant *FoldBitCast(Constant *V, Type *DestTy) { - Type *SrcTy = V->getType(); - if (SrcTy == DestTy) - return V; // no-op cast - - // Check to see if we are casting a pointer to an aggregate to a pointer to - // the first element. If so, return the appropriate GEP instruction. - if (PointerType *PTy = dyn_cast<PointerType>(V->getType())) - if (PointerType *DPTy = dyn_cast<PointerType>(DestTy)) - if (PTy->getAddressSpace() == DPTy->getAddressSpace() - && DPTy->getElementType()->isSized()) { - SmallVector<Value*, 8> IdxList; - Value *Zero = - Constant::getNullValue(Type::getInt32Ty(DPTy->getContext())); - IdxList.push_back(Zero); - Type *ElTy = PTy->getElementType(); - while (ElTy != DPTy->getElementType()) { - if (StructType *STy = dyn_cast<StructType>(ElTy)) { - if (STy->getNumElements() == 0) break; - ElTy = STy->getElementType(0); - IdxList.push_back(Zero); - } else if (SequentialType *STy = - dyn_cast<SequentialType>(ElTy)) { - if (ElTy->isPointerTy()) break; // Can't index into pointers! - ElTy = STy->getElementType(); - IdxList.push_back(Zero); - } else { - break; - } - } - - if (ElTy == DPTy->getElementType()) - // This GEP is inbounds because all indices are zero. - return ConstantExpr::getInBoundsGetElementPtr(V, IdxList); - } - - // Handle casts from one vector constant to another. We know that the src - // and dest type have the same size (otherwise its an illegal cast). - if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { - if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { - assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && - "Not cast between same sized vectors!"); - SrcTy = NULL; - // First, check for null. Undef is already handled. - if (isa<ConstantAggregateZero>(V)) - return Constant::getNullValue(DestTy); - - // Handle ConstantVector and ConstantAggregateVector. - return BitCastConstantVector(V, DestPTy); - } - - // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts - // This allows for other simplifications (although some of them - // can only be handled by Analysis/ConstantFolding.cpp). - if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) - return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy); - } - - // Finally, implement bitcast folding now. The code below doesn't handle - // bitcast right. - if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. - return ConstantPointerNull::get(cast<PointerType>(DestTy)); - - // Handle integral constant input. - if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { - if (DestTy->isIntegerTy()) - // Integral -> Integral. This is a no-op because the bit widths must - // be the same. Consequently, we just fold to V. - return V; - - if (DestTy->isFloatingPointTy()) - return ConstantFP::get(DestTy->getContext(), - APFloat(CI->getValue(), - !DestTy->isPPC_FP128Ty())); - - // Otherwise, can't fold this (vector?) - return 0; - } - - // Handle ConstantFP input: FP -> Integral. - if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) - return ConstantInt::get(FP->getContext(), - FP->getValueAPF().bitcastToAPInt()); - - return 0; -} - - -/// ExtractConstantBytes - V is an integer constant which only has a subset of -/// its bytes used. The bytes used are indicated by ByteStart (which is the -/// first byte used, counting from the least significant byte) and ByteSize, -/// which is the number of bytes used. -/// -/// This function analyzes the specified constant to see if the specified byte -/// range can be returned as a simplified constant. If so, the constant is -/// returned, otherwise null is returned. -/// -static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, - unsigned ByteSize) { - assert(C->getType()->isIntegerTy() && - (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 && - "Non-byte sized integer input"); - unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; - assert(ByteSize && "Must be accessing some piece"); - assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input"); - assert(ByteSize != CSize && "Should not extract everything"); - - // Constant Integers are simple. - if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { - APInt V = CI->getValue(); - if (ByteStart) - V = V.lshr(ByteStart*8); - V = V.trunc(ByteSize*8); - return ConstantInt::get(CI->getContext(), V); - } - - // In the input is a constant expr, we might be able to recursively simplify. - // If not, we definitely can't do anything. - ConstantExpr *CE = dyn_cast<ConstantExpr>(C); - if (CE == 0) return 0; - - switch (CE->getOpcode()) { - default: return 0; - case Instruction::Or: { - Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); - if (RHS == 0) - return 0; - - // X | -1 -> -1. - if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) - if (RHSC->isAllOnesValue()) - return RHSC; - - Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); - if (LHS == 0) - return 0; - return ConstantExpr::getOr(LHS, RHS); - } - case Instruction::And: { - Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); - if (RHS == 0) - return 0; - - // X & 0 -> 0. - if (RHS->isNullValue()) - return RHS; - - Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); - if (LHS == 0) - return 0; - return ConstantExpr::getAnd(LHS, RHS); - } - case Instruction::LShr: { - ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); - if (Amt == 0) - return 0; - unsigned ShAmt = Amt->getZExtValue(); - // Cannot analyze non-byte shifts. - if ((ShAmt & 7) != 0) - return 0; - ShAmt >>= 3; - - // If the extract is known to be all zeros, return zero. - if (ByteStart >= CSize-ShAmt) - return Constant::getNullValue(IntegerType::get(CE->getContext(), - ByteSize*8)); - // If the extract is known to be fully in the input, extract it. - if (ByteStart+ByteSize+ShAmt <= CSize) - return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize); - - // TODO: Handle the 'partially zero' case. - return 0; - } - - case Instruction::Shl: { - ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); - if (Amt == 0) - return 0; - unsigned ShAmt = Amt->getZExtValue(); - // Cannot analyze non-byte shifts. - if ((ShAmt & 7) != 0) - return 0; - ShAmt >>= 3; - - // If the extract is known to be all zeros, return zero. - if (ByteStart+ByteSize <= ShAmt) - return Constant::getNullValue(IntegerType::get(CE->getContext(), - ByteSize*8)); - // If the extract is known to be fully in the input, extract it. - if (ByteStart >= ShAmt) - return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize); - - // TODO: Handle the 'partially zero' case. - return 0; - } - - case Instruction::ZExt: { - unsigned SrcBitSize = - cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth(); - - // If extracting something that is completely zero, return 0. - if (ByteStart*8 >= SrcBitSize) - return Constant::getNullValue(IntegerType::get(CE->getContext(), - ByteSize*8)); - - // If exactly extracting the input, return it. - if (ByteStart == 0 && ByteSize*8 == SrcBitSize) - return CE->getOperand(0); - - // If extracting something completely in the input, if if the input is a - // multiple of 8 bits, recurse. - if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize) - return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize); - - // Otherwise, if extracting a subset of the input, which is not multiple of - // 8 bits, do a shift and trunc to get the bits. - if ((ByteStart+ByteSize)*8 < SrcBitSize) { - assert((SrcBitSize&7) && "Shouldn't get byte sized case here"); - Constant *Res = CE->getOperand(0); - if (ByteStart) - Res = ConstantExpr::getLShr(Res, - ConstantInt::get(Res->getType(), ByteStart*8)); - return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(), - ByteSize*8)); - } - - // TODO: Handle the 'partially zero' case. - return 0; - } - } -} - -/// getFoldedSizeOf - Return a ConstantExpr with type DestTy for sizeof -/// on Ty, with any known factors factored out. If Folded is false, -/// return null if no factoring was possible, to avoid endlessly -/// bouncing an unfoldable expression back into the top-level folder. -/// -static Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, - bool Folded) { - if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { - Constant *N = ConstantInt::get(DestTy, ATy->getNumElements()); - Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); - return ConstantExpr::getNUWMul(E, N); - } - - if (StructType *STy = dyn_cast<StructType>(Ty)) - if (!STy->isPacked()) { - unsigned NumElems = STy->getNumElements(); - // An empty struct has size zero. - if (NumElems == 0) - return ConstantExpr::getNullValue(DestTy); - // Check for a struct with all members having the same size. - Constant *MemberSize = - getFoldedSizeOf(STy->getElementType(0), DestTy, true); - bool AllSame = true; - for (unsigned i = 1; i != NumElems; ++i) - if (MemberSize != - getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { - AllSame = false; - break; - } - if (AllSame) { - Constant *N = ConstantInt::get(DestTy, NumElems); - return ConstantExpr::getNUWMul(MemberSize, N); - } - } - - // Pointer size doesn't depend on the pointee type, so canonicalize them - // to an arbitrary pointee. - if (PointerType *PTy = dyn_cast<PointerType>(Ty)) - if (!PTy->getElementType()->isIntegerTy(1)) - return - getFoldedSizeOf(PointerType::get(IntegerType::get(PTy->getContext(), 1), - PTy->getAddressSpace()), - DestTy, true); - - // If there's no interesting folding happening, bail so that we don't create - // a constant that looks like it needs folding but really doesn't. - if (!Folded) - return 0; - - // Base case: Get a regular sizeof expression. - Constant *C = ConstantExpr::getSizeOf(Ty); - C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, - DestTy, false), - C, DestTy); - return C; -} - -/// getFoldedAlignOf - Return a ConstantExpr with type DestTy for alignof -/// on Ty, with any known factors factored out. If Folded is false, -/// return null if no factoring was possible, to avoid endlessly -/// bouncing an unfoldable expression back into the top-level folder. -/// -static Constant *getFoldedAlignOf(Type *Ty, Type *DestTy, - bool Folded) { - // The alignment of an array is equal to the alignment of the - // array element. Note that this is not always true for vectors. - if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { - Constant *C = ConstantExpr::getAlignOf(ATy->getElementType()); - C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, - DestTy, - false), - C, DestTy); - return C; - } - - if (StructType *STy = dyn_cast<StructType>(Ty)) { - // Packed structs always have an alignment of 1. - if (STy->isPacked()) - return ConstantInt::get(DestTy, 1); - - // Otherwise, struct alignment is the maximum alignment of any member. - // Without target data, we can't compare much, but we can check to see - // if all the members have the same alignment. - unsigned NumElems = STy->getNumElements(); - // An empty struct has minimal alignment. - if (NumElems == 0) - return ConstantInt::get(DestTy, 1); - // Check for a struct with all members having the same alignment. - Constant *MemberAlign = - getFoldedAlignOf(STy->getElementType(0), DestTy, true); - bool AllSame = true; - for (unsigned i = 1; i != NumElems; ++i) - if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) { - AllSame = false; - break; - } - if (AllSame) - return MemberAlign; - } - - // Pointer alignment doesn't depend on the pointee type, so canonicalize them - // to an arbitrary pointee. - if (PointerType *PTy = dyn_cast<PointerType>(Ty)) - if (!PTy->getElementType()->isIntegerTy(1)) - return - getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(), - 1), - PTy->getAddressSpace()), - DestTy, true); - - // If there's no interesting folding happening, bail so that we don't create - // a constant that looks like it needs folding but really doesn't. - if (!Folded) - return 0; - - // Base case: Get a regular alignof expression. - Constant *C = ConstantExpr::getAlignOf(Ty); - C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, - DestTy, false), - C, DestTy); - return C; -} - -/// getFoldedOffsetOf - Return a ConstantExpr with type DestTy for offsetof -/// on Ty and FieldNo, with any known factors factored out. If Folded is false, -/// return null if no factoring was possible, to avoid endlessly -/// bouncing an unfoldable expression back into the top-level folder. -/// -static Constant *getFoldedOffsetOf(Type *Ty, Constant *FieldNo, - Type *DestTy, - bool Folded) { - if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { - Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false, - DestTy, false), - FieldNo, DestTy); - Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); - return ConstantExpr::getNUWMul(E, N); - } - - if (StructType *STy = dyn_cast<StructType>(Ty)) - if (!STy->isPacked()) { - unsigned NumElems = STy->getNumElements(); - // An empty struct has no members. - if (NumElems == 0) - return 0; - // Check for a struct with all members having the same size. - Constant *MemberSize = - getFoldedSizeOf(STy->getElementType(0), DestTy, true); - bool AllSame = true; - for (unsigned i = 1; i != NumElems; ++i) - if (MemberSize != - getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { - AllSame = false; - break; - } - if (AllSame) { - Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, - false, - DestTy, - false), - FieldNo, DestTy); - return ConstantExpr::getNUWMul(MemberSize, N); - } - } - - // If there's no interesting folding happening, bail so that we don't create - // a constant that looks like it needs folding but really doesn't. - if (!Folded) - return 0; - - // Base case: Get a regular offsetof expression. - Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo); - C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, - DestTy, false), - C, DestTy); - return C; -} - -Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, - Type *DestTy) { - if (isa<UndefValue>(V)) { - // zext(undef) = 0, because the top bits will be zero. - // sext(undef) = 0, because the top bits will all be the same. - // [us]itofp(undef) = 0, because the result value is bounded. - if (opc == Instruction::ZExt || opc == Instruction::SExt || - opc == Instruction::UIToFP || opc == Instruction::SIToFP) - return Constant::getNullValue(DestTy); - return UndefValue::get(DestTy); - } - - if (V->isNullValue() && !DestTy->isX86_MMXTy()) - return Constant::getNullValue(DestTy); - - // If the cast operand is a constant expression, there's a few things we can - // do to try to simplify it. - if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { - if (CE->isCast()) { - // Try hard to fold cast of cast because they are often eliminable. - if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) - return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); - } else if (CE->getOpcode() == Instruction::GetElementPtr) { - // If all of the indexes in the GEP are null values, there is no pointer - // adjustment going on. We might as well cast the source pointer. - bool isAllNull = true; - for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) - if (!CE->getOperand(i)->isNullValue()) { - isAllNull = false; - break; - } - if (isAllNull) - // This is casting one pointer type to another, always BitCast - return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); - } - } - - // If the cast operand is a constant vector, perform the cast by - // operating on each element. In the cast of bitcasts, the element - // count may be mismatched; don't attempt to handle that here. - if ((isa<ConstantVector>(V) || isa<ConstantDataVector>(V)) && - DestTy->isVectorTy() && - DestTy->getVectorNumElements() == V->getType()->getVectorNumElements()) { - SmallVector<Constant*, 16> res; - VectorType *DestVecTy = cast<VectorType>(DestTy); - Type *DstEltTy = DestVecTy->getElementType(); - Type *Ty = IntegerType::get(V->getContext(), 32); - for (unsigned i = 0, e = V->getType()->getVectorNumElements(); i != e; ++i) { - Constant *C = - ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i)); - res.push_back(ConstantExpr::getCast(opc, C, DstEltTy)); - } - return ConstantVector::get(res); - } - - // We actually have to do a cast now. Perform the cast according to the - // opcode specified. - switch (opc) { - default: - llvm_unreachable("Failed to cast constant expression"); - case Instruction::FPTrunc: - case Instruction::FPExt: - if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { - bool ignored; - APFloat Val = FPC->getValueAPF(); - Val.convert(DestTy->isHalfTy() ? APFloat::IEEEhalf : - DestTy->isFloatTy() ? APFloat::IEEEsingle : - DestTy->isDoubleTy() ? APFloat::IEEEdouble : - DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended : - DestTy->isFP128Ty() ? APFloat::IEEEquad : - DestTy->isPPC_FP128Ty() ? APFloat::PPCDoubleDouble : - APFloat::Bogus, - APFloat::rmNearestTiesToEven, &ignored); - return ConstantFP::get(V->getContext(), Val); - } - return 0; // Can't fold. - case Instruction::FPToUI: - case Instruction::FPToSI: - if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { - const APFloat &V = FPC->getValueAPF(); - bool ignored; - uint64_t x[2]; - uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); - (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, - APFloat::rmTowardZero, &ignored); - APInt Val(DestBitWidth, x); - return ConstantInt::get(FPC->getContext(), Val); - } - return 0; // Can't fold. - case Instruction::IntToPtr: //always treated as unsigned - if (V->isNullValue()) // Is it an integral null value? - return ConstantPointerNull::get(cast<PointerType>(DestTy)); - return 0; // Other pointer types cannot be casted - case Instruction::PtrToInt: // always treated as unsigned - // Is it a null pointer value? - if (V->isNullValue()) - return ConstantInt::get(DestTy, 0); - // If this is a sizeof-like expression, pull out multiplications by - // known factors to expose them to subsequent folding. If it's an - // alignof-like expression, factor out known factors. - if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) - if (CE->getOpcode() == Instruction::GetElementPtr && - CE->getOperand(0)->isNullValue()) { - Type *Ty = - cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); - if (CE->getNumOperands() == 2) { - // Handle a sizeof-like expression. - Constant *Idx = CE->getOperand(1); - bool isOne = isa<ConstantInt>(Idx) && cast<ConstantInt>(Idx)->isOne(); - if (Constant *C = getFoldedSizeOf(Ty, DestTy, !isOne)) { - Idx = ConstantExpr::getCast(CastInst::getCastOpcode(Idx, true, - DestTy, false), - Idx, DestTy); - return ConstantExpr::getMul(C, Idx); - } - } else if (CE->getNumOperands() == 3 && - CE->getOperand(1)->isNullValue()) { - // Handle an alignof-like expression. - if (StructType *STy = dyn_cast<StructType>(Ty)) - if (!STy->isPacked()) { - ConstantInt *CI = cast<ConstantInt>(CE->getOperand(2)); - if (CI->isOne() && - STy->getNumElements() == 2 && - STy->getElementType(0)->isIntegerTy(1)) { - return getFoldedAlignOf(STy->getElementType(1), DestTy, false); - } - } - // Handle an offsetof-like expression. - if (Ty->isStructTy() || Ty->isArrayTy()) { - if (Constant *C = getFoldedOffsetOf(Ty, CE->getOperand(2), - DestTy, false)) - return C; - } - } - } - // Other pointer types cannot be casted - return 0; - case Instruction::UIToFP: - case Instruction::SIToFP: - if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { - APInt api = CI->getValue(); - APFloat apf(APInt::getNullValue(DestTy->getPrimitiveSizeInBits()), - !DestTy->isPPC_FP128Ty() /* isEEEE */); - (void)apf.convertFromAPInt(api, - opc==Instruction::SIToFP, - APFloat::rmNearestTiesToEven); - return ConstantFP::get(V->getContext(), apf); - } - return 0; - case Instruction::ZExt: - if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { - uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); - return ConstantInt::get(V->getContext(), - CI->getValue().zext(BitWidth)); - } - return 0; - case Instruction::SExt: - if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { - uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); - return ConstantInt::get(V->getContext(), - CI->getValue().sext(BitWidth)); - } - return 0; - case Instruction::Trunc: { - uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); - if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { - return ConstantInt::get(V->getContext(), - CI->getValue().trunc(DestBitWidth)); - } - - // The input must be a constantexpr. See if we can simplify this based on - // the bytes we are demanding. Only do this if the source and dest are an - // even multiple of a byte. - if ((DestBitWidth & 7) == 0 && - (cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0) - if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8)) - return Res; - - return 0; - } - case Instruction::BitCast: - return FoldBitCast(V, DestTy); - } -} - -Constant *llvm::ConstantFoldSelectInstruction(Constant *Cond, - Constant *V1, Constant *V2) { - // Check for i1 and vector true/false conditions. - if (Cond->isNullValue()) return V2; - if (Cond->isAllOnesValue()) return V1; - - // If the condition is a vector constant, fold the result elementwise. - if (ConstantVector *CondV = dyn_cast<ConstantVector>(Cond)) { - SmallVector<Constant*, 16> Result; - Type *Ty = IntegerType::get(CondV->getContext(), 32); - for (unsigned i = 0, e = V1->getType()->getVectorNumElements(); i != e;++i){ - ConstantInt *Cond = dyn_cast<ConstantInt>(CondV->getOperand(i)); - if (Cond == 0) break; - - Constant *V = Cond->isNullValue() ? V2 : V1; - Constant *Res = ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i)); - Result.push_back(Res); - } - - // If we were able to build the vector, return it. - if (Result.size() == V1->getType()->getVectorNumElements()) - return ConstantVector::get(Result); - } - - if (isa<UndefValue>(Cond)) { - if (isa<UndefValue>(V1)) return V1; - return V2; - } - if (isa<UndefValue>(V1)) return V2; - if (isa<UndefValue>(V2)) return V1; - if (V1 == V2) return V1; - - if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) { - if (TrueVal->getOpcode() == Instruction::Select) - if (TrueVal->getOperand(0) == Cond) - return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2); - } - if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) { - if (FalseVal->getOpcode() == Instruction::Select) - if (FalseVal->getOperand(0) == Cond) - return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2)); - } - - return 0; -} - -Constant *llvm::ConstantFoldExtractElementInstruction(Constant *Val, - Constant *Idx) { - if (isa<UndefValue>(Val)) // ee(undef, x) -> undef - return UndefValue::get(Val->getType()->getVectorElementType()); - if (Val->isNullValue()) // ee(zero, x) -> zero - return Constant::getNullValue(Val->getType()->getVectorElementType()); - // ee({w,x,y,z}, undef) -> undef - if (isa<UndefValue>(Idx)) - return UndefValue::get(Val->getType()->getVectorElementType()); - - if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { - uint64_t Index = CIdx->getZExtValue(); - // ee({w,x,y,z}, wrong_value) -> undef - if (Index >= Val->getType()->getVectorNumElements()) - return UndefValue::get(Val->getType()->getVectorElementType()); - return Val->getAggregateElement(Index); - } - return 0; -} - -Constant *llvm::ConstantFoldInsertElementInstruction(Constant *Val, - Constant *Elt, - Constant *Idx) { - ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); - if (!CIdx) return 0; - const APInt &IdxVal = CIdx->getValue(); - - SmallVector<Constant*, 16> Result; - Type *Ty = IntegerType::get(Val->getContext(), 32); - for (unsigned i = 0, e = Val->getType()->getVectorNumElements(); i != e; ++i){ - if (i == IdxVal) { - Result.push_back(Elt); - continue; - } - - Constant *C = - ConstantExpr::getExtractElement(Val, ConstantInt::get(Ty, i)); - Result.push_back(C); - } - - return ConstantVector::get(Result); -} - -Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1, - Constant *V2, - Constant *Mask) { - unsigned MaskNumElts = Mask->getType()->getVectorNumElements(); - Type *EltTy = V1->getType()->getVectorElementType(); - - // Undefined shuffle mask -> undefined value. - if (isa<UndefValue>(Mask)) - return UndefValue::get(VectorType::get(EltTy, MaskNumElts)); - - // Don't break the bitcode reader hack. - if (isa<ConstantExpr>(Mask)) return 0; - - unsigned SrcNumElts = V1->getType()->getVectorNumElements(); - - // Loop over the shuffle mask, evaluating each element. - SmallVector<Constant*, 32> Result; - for (unsigned i = 0; i != MaskNumElts; ++i) { - int Elt = ShuffleVectorInst::getMaskValue(Mask, i); - if (Elt == -1) { - Result.push_back(UndefValue::get(EltTy)); - continue; - } - Constant *InElt; - if (unsigned(Elt) >= SrcNumElts*2) - InElt = UndefValue::get(EltTy); - else if (unsigned(Elt) >= SrcNumElts) { - Type *Ty = IntegerType::get(V2->getContext(), 32); - InElt = - ConstantExpr::getExtractElement(V2, - ConstantInt::get(Ty, Elt - SrcNumElts)); - } else { - Type *Ty = IntegerType::get(V1->getContext(), 32); - InElt = ConstantExpr::getExtractElement(V1, ConstantInt::get(Ty, Elt)); - } - Result.push_back(InElt); - } - - return ConstantVector::get(Result); -} - -Constant *llvm::ConstantFoldExtractValueInstruction(Constant *Agg, - ArrayRef<unsigned> Idxs) { - // Base case: no indices, so return the entire value. - if (Idxs.empty()) - return Agg; - - if (Constant *C = Agg->getAggregateElement(Idxs[0])) - return ConstantFoldExtractValueInstruction(C, Idxs.slice(1)); - - return 0; -} - -Constant *llvm::ConstantFoldInsertValueInstruction(Constant *Agg, - Constant *Val, - ArrayRef<unsigned> Idxs) { - // Base case: no indices, so replace the entire value. - if (Idxs.empty()) - return Val; - - unsigned NumElts; - if (StructType *ST = dyn_cast<StructType>(Agg->getType())) - NumElts = ST->getNumElements(); - else if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) - NumElts = AT->getNumElements(); - else - NumElts = AT->getVectorNumElements(); - - SmallVector<Constant*, 32> Result; - for (unsigned i = 0; i != NumElts; ++i) { - Constant *C = Agg->getAggregateElement(i); - if (C == 0) return 0; - - if (Idxs[0] == i) - C = ConstantFoldInsertValueInstruction(C, Val, Idxs.slice(1)); - - Result.push_back(C); - } - - if (StructType *ST = dyn_cast<StructType>(Agg->getType())) - return ConstantStruct::get(ST, Result); - if (ArrayType *AT = dyn_cast<ArrayType>(Agg->getType())) - return ConstantArray::get(AT, Result); - return ConstantVector::get(Result); -} - - -Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, - Constant *C1, Constant *C2) { - // Handle UndefValue up front. - if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { - switch (Opcode) { - case Instruction::Xor: - if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) - // Handle undef ^ undef -> 0 special case. This is a common - // idiom (misuse). - return Constant::getNullValue(C1->getType()); - // Fallthrough - case Instruction::Add: - case Instruction::Sub: - return UndefValue::get(C1->getType()); - case Instruction::And: - if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef & undef -> undef - return C1; - return Constant::getNullValue(C1->getType()); // undef & X -> 0 - case Instruction::Mul: { - ConstantInt *CI; - // X * undef -> undef if X is odd or undef - if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) || - ((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) || - (isa<UndefValue>(C1) && isa<UndefValue>(C2))) - return UndefValue::get(C1->getType()); - - // X * undef -> 0 otherwise - return Constant::getNullValue(C1->getType()); - } - case Instruction::UDiv: - case Instruction::SDiv: - // undef / 1 -> undef - if (Opcode == Instruction::UDiv || Opcode == Instruction::SDiv) - if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) - if (CI2->isOne()) - return C1; - // FALL THROUGH - case Instruction::URem: - case Instruction::SRem: - if (!isa<UndefValue>(C2)) // undef / X -> 0 - return Constant::getNullValue(C1->getType()); - return C2; // X / undef -> undef - case Instruction::Or: // X | undef -> -1 - if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef - return C1; - return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0 - case Instruction::LShr: - if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) - return C1; // undef lshr undef -> undef - return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 - // undef lshr X -> 0 - case Instruction::AShr: - if (!isa<UndefValue>(C2)) // undef ashr X --> all ones - return Constant::getAllOnesValue(C1->getType()); - else if (isa<UndefValue>(C1)) - return C1; // undef ashr undef -> undef - else - return C1; // X ashr undef --> X - case Instruction::Shl: - if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) - return C1; // undef shl undef -> undef - // undef << X -> 0 or X << undef -> 0 - return Constant::getNullValue(C1->getType()); - } - } - - // Handle simplifications when the RHS is a constant int. - if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { - switch (Opcode) { - case Instruction::Add: - if (CI2->equalsInt(0)) return C1; // X + 0 == X - break; - case Instruction::Sub: - if (CI2->equalsInt(0)) return C1; // X - 0 == X - break; - case Instruction::Mul: - if (CI2->equalsInt(0)) return C2; // X * 0 == 0 - if (CI2->equalsInt(1)) - return C1; // X * 1 == X - break; - case Instruction::UDiv: - case Instruction::SDiv: - if (CI2->equalsInt(1)) - return C1; // X / 1 == X - if (CI2->equalsInt(0)) - return UndefValue::get(CI2->getType()); // X / 0 == undef - break; - case Instruction::URem: - case Instruction::SRem: - if (CI2->equalsInt(1)) - return Constant::getNullValue(CI2->getType()); // X % 1 == 0 - if (CI2->equalsInt(0)) - return UndefValue::get(CI2->getType()); // X % 0 == undef - break; - case Instruction::And: - if (CI2->isZero()) return C2; // X & 0 == 0 - if (CI2->isAllOnesValue()) - return C1; // X & -1 == X - - if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { - // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) - if (CE1->getOpcode() == Instruction::ZExt) { - unsigned DstWidth = CI2->getType()->getBitWidth(); - unsigned SrcWidth = - CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); - APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); - if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) - return C1; - } - - // If and'ing the address of a global with a constant, fold it. - if (CE1->getOpcode() == Instruction::PtrToInt && - isa<GlobalValue>(CE1->getOperand(0))) { - GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0)); - - // Functions are at least 4-byte aligned. - unsigned GVAlign = GV->getAlignment(); - if (isa<Function>(GV)) - GVAlign = std::max(GVAlign, 4U); - - if (GVAlign > 1) { - unsigned DstWidth = CI2->getType()->getBitWidth(); - unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign)); - APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth)); - - // If checking bits we know are clear, return zero. - if ((CI2->getValue() & BitsNotSet) == CI2->getValue()) - return Constant::getNullValue(CI2->getType()); - } - } - } - break; - case Instruction::Or: - if (CI2->equalsInt(0)) return C1; // X | 0 == X - if (CI2->isAllOnesValue()) - return C2; // X | -1 == -1 - break; - case Instruction::Xor: - if (CI2->equalsInt(0)) return C1; // X ^ 0 == X - - if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { - switch (CE1->getOpcode()) { - default: break; - case Instruction::ICmp: - case Instruction::FCmp: - // cmp pred ^ true -> cmp !pred - assert(CI2->equalsInt(1)); - CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate(); - pred = CmpInst::getInversePredicate(pred); - return ConstantExpr::getCompare(pred, CE1->getOperand(0), - CE1->getOperand(1)); - } - } - break; - case Instruction::AShr: - // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 - if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) - if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. - return ConstantExpr::getLShr(C1, C2); - break; - } - } else if (isa<ConstantInt>(C1)) { - // If C1 is a ConstantInt and C2 is not, swap the operands. - if (Instruction::isCommutative(Opcode)) - return ConstantExpr::get(Opcode, C2, C1); - } - - // At this point we know neither constant is an UndefValue. - if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { - if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { - const APInt &C1V = CI1->getValue(); - const APInt &C2V = CI2->getValue(); - switch (Opcode) { - default: - break; - case Instruction::Add: - return ConstantInt::get(CI1->getContext(), C1V + C2V); - case Instruction::Sub: - return ConstantInt::get(CI1->getContext(), C1V - C2V); - case Instruction::Mul: - return ConstantInt::get(CI1->getContext(), C1V * C2V); - case Instruction::UDiv: - assert(!CI2->isNullValue() && "Div by zero handled above"); - return ConstantInt::get(CI1->getContext(), C1V.udiv(C2V)); - case Instruction::SDiv: - assert(!CI2->isNullValue() && "Div by zero handled above"); - if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) - return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef - return ConstantInt::get(CI1->getContext(), C1V.sdiv(C2V)); - case Instruction::URem: - assert(!CI2->isNullValue() && "Div by zero handled above"); - return ConstantInt::get(CI1->getContext(), C1V.urem(C2V)); - case Instruction::SRem: - assert(!CI2->isNullValue() && "Div by zero handled above"); - if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) - return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef - return ConstantInt::get(CI1->getContext(), C1V.srem(C2V)); - case Instruction::And: - return ConstantInt::get(CI1->getContext(), C1V & C2V); - case Instruction::Or: - return ConstantInt::get(CI1->getContext(), C1V | C2V); - case Instruction::Xor: - return ConstantInt::get(CI1->getContext(), C1V ^ C2V); - case Instruction::Shl: { - uint32_t shiftAmt = C2V.getZExtValue(); - if (shiftAmt < C1V.getBitWidth()) - return ConstantInt::get(CI1->getContext(), C1V.shl(shiftAmt)); - else - return UndefValue::get(C1->getType()); // too big shift is undef - } - case Instruction::LShr: { - uint32_t shiftAmt = C2V.getZExtValue(); - if (shiftAmt < C1V.getBitWidth()) - return ConstantInt::get(CI1->getContext(), C1V.lshr(shiftAmt)); - else - return UndefValue::get(C1->getType()); // too big shift is undef - } - case Instruction::AShr: { - uint32_t shiftAmt = C2V.getZExtValue(); - if (shiftAmt < C1V.getBitWidth()) - return ConstantInt::get(CI1->getContext(), C1V.ashr(shiftAmt)); - else - return UndefValue::get(C1->getType()); // too big shift is undef - } - } - } - - switch (Opcode) { - case Instruction::SDiv: - case Instruction::UDiv: - case Instruction::URem: - case Instruction::SRem: - case Instruction::LShr: - case Instruction::AShr: - case Instruction::Shl: - if (CI1->equalsInt(0)) return C1; - break; - default: - break; - } - } else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { - if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { - APFloat C1V = CFP1->getValueAPF(); - APFloat C2V = CFP2->getValueAPF(); - APFloat C3V = C1V; // copy for modification - switch (Opcode) { - default: - break; - case Instruction::FAdd: - (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); - return ConstantFP::get(C1->getContext(), C3V); - case Instruction::FSub: - (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); - return ConstantFP::get(C1->getContext(), C3V); - case Instruction::FMul: - (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); - return ConstantFP::get(C1->getContext(), C3V); - case Instruction::FDiv: - (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); - return ConstantFP::get(C1->getContext(), C3V); - case Instruction::FRem: - (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven); - return ConstantFP::get(C1->getContext(), C3V); - } - } - } else if (VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { - // Perform elementwise folding. - SmallVector<Constant*, 16> Result; - Type *Ty = IntegerType::get(VTy->getContext(), 32); - for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { - Constant *LHS = - ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, i)); - Constant *RHS = - ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, i)); - - Result.push_back(ConstantExpr::get(Opcode, LHS, RHS)); - } - - return ConstantVector::get(Result); - } - - if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { - // There are many possible foldings we could do here. We should probably - // at least fold add of a pointer with an integer into the appropriate - // getelementptr. This will improve alias analysis a bit. - - // Given ((a + b) + c), if (b + c) folds to something interesting, return - // (a + (b + c)). - if (Instruction::isAssociative(Opcode) && CE1->getOpcode() == Opcode) { - Constant *T = ConstantExpr::get(Opcode, CE1->getOperand(1), C2); - if (!isa<ConstantExpr>(T) || cast<ConstantExpr>(T)->getOpcode() != Opcode) - return ConstantExpr::get(Opcode, CE1->getOperand(0), T); - } - } else if (isa<ConstantExpr>(C2)) { - // If C2 is a constant expr and C1 isn't, flop them around and fold the - // other way if possible. - if (Instruction::isCommutative(Opcode)) - return ConstantFoldBinaryInstruction(Opcode, C2, C1); - } - - // i1 can be simplified in many cases. - if (C1->getType()->isIntegerTy(1)) { - switch (Opcode) { - case Instruction::Add: - case Instruction::Sub: - return ConstantExpr::getXor(C1, C2); - case Instruction::Mul: - return ConstantExpr::getAnd(C1, C2); - case Instruction::Shl: - case Instruction::LShr: - case Instruction::AShr: - // We can assume that C2 == 0. If it were one the result would be - // undefined because the shift value is as large as the bitwidth. - return C1; - case Instruction::SDiv: - case Instruction::UDiv: - // We can assume that C2 == 1. If it were zero the result would be - // undefined through division by zero. - return C1; - case Instruction::URem: - case Instruction::SRem: - // We can assume that C2 == 1. If it were zero the result would be - // undefined through division by zero. - return ConstantInt::getFalse(C1->getContext()); - default: - break; - } - } - - // We don't know how to fold this. - return 0; -} - -/// isZeroSizedType - This type is zero sized if its an array or structure of -/// zero sized types. The only leaf zero sized type is an empty structure. -static bool isMaybeZeroSizedType(Type *Ty) { - if (StructType *STy = dyn_cast<StructType>(Ty)) { - if (STy->isOpaque()) return true; // Can't say. - - // If all of elements have zero size, this does too. - for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) - if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; - return true; - - } else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { - return isMaybeZeroSizedType(ATy->getElementType()); - } - return false; -} - -/// IdxCompare - Compare the two constants as though they were getelementptr -/// indices. This allows coersion of the types to be the same thing. -/// -/// If the two constants are the "same" (after coersion), return 0. If the -/// first is less than the second, return -1, if the second is less than the -/// first, return 1. If the constants are not integral, return -2. -/// -static int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) { - if (C1 == C2) return 0; - - // Ok, we found a different index. If they are not ConstantInt, we can't do - // anything with them. - if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) - return -2; // don't know! - - // Ok, we have two differing integer indices. Sign extend them to be the same - // type. Long is always big enough, so we use it. - if (!C1->getType()->isIntegerTy(64)) - C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(C1->getContext())); - - if (!C2->getType()->isIntegerTy(64)) - C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(C1->getContext())); - - if (C1 == C2) return 0; // They are equal - - // If the type being indexed over is really just a zero sized type, there is - // no pointer difference being made here. - if (isMaybeZeroSizedType(ElTy)) - return -2; // dunno. - - // If they are really different, now that they are the same type, then we - // found a difference! - if (cast<ConstantInt>(C1)->getSExtValue() < - cast<ConstantInt>(C2)->getSExtValue()) - return -1; - else - return 1; -} - -/// evaluateFCmpRelation - This function determines if there is anything we can -/// decide about the two constants provided. This doesn't need to handle simple -/// things like ConstantFP comparisons, but should instead handle ConstantExprs. -/// If we can determine that the two constants have a particular relation to -/// each other, we should return the corresponding FCmpInst predicate, -/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in -/// ConstantFoldCompareInstruction. -/// -/// To simplify this code we canonicalize the relation so that the first -/// operand is always the most "complex" of the two. We consider ConstantFP -/// to be the simplest, and ConstantExprs to be the most complex. -static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) { - assert(V1->getType() == V2->getType() && - "Cannot compare values of different types!"); - - // Handle degenerate case quickly - if (V1 == V2) return FCmpInst::FCMP_OEQ; - - if (!isa<ConstantExpr>(V1)) { - if (!isa<ConstantExpr>(V2)) { - // We distilled thisUse the standard constant folder for a few cases - ConstantInt *R = 0; - R = dyn_cast<ConstantInt>( - ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2)); - if (R && !R->isZero()) - return FCmpInst::FCMP_OEQ; - R = dyn_cast<ConstantInt>( - ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2)); - if (R && !R->isZero()) - return FCmpInst::FCMP_OLT; - R = dyn_cast<ConstantInt>( - ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2)); - if (R && !R->isZero()) - return FCmpInst::FCMP_OGT; - - // Nothing more we can do - return FCmpInst::BAD_FCMP_PREDICATE; - } - - // If the first operand is simple and second is ConstantExpr, swap operands. - FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); - if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) - return FCmpInst::getSwappedPredicate(SwappedRelation); - } else { - // Ok, the LHS is known to be a constantexpr. The RHS can be any of a - // constantexpr or a simple constant. - ConstantExpr *CE1 = cast<ConstantExpr>(V1); - switch (CE1->getOpcode()) { - case Instruction::FPTrunc: - case Instruction::FPExt: - case Instruction::UIToFP: - case Instruction::SIToFP: - // We might be able to do something with these but we don't right now. - break; - default: - break; - } - } - // There are MANY other foldings that we could perform here. They will - // probably be added on demand, as they seem needed. - return FCmpInst::BAD_FCMP_PREDICATE; -} - -/// evaluateICmpRelation - This function determines if there is anything we can -/// decide about the two constants provided. This doesn't need to handle simple -/// things like integer comparisons, but should instead handle ConstantExprs -/// and GlobalValues. If we can determine that the two constants have a -/// particular relation to each other, we should return the corresponding ICmp -/// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. -/// -/// To simplify this code we canonicalize the relation so that the first -/// operand is always the most "complex" of the two. We consider simple -/// constants (like ConstantInt) to be the simplest, followed by -/// GlobalValues, followed by ConstantExpr's (the most complex). -/// -static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, - bool isSigned) { - assert(V1->getType() == V2->getType() && - "Cannot compare different types of values!"); - if (V1 == V2) return ICmpInst::ICMP_EQ; - - if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) && - !isa<BlockAddress>(V1)) { - if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) && - !isa<BlockAddress>(V2)) { - // We distilled this down to a simple case, use the standard constant - // folder. - ConstantInt *R = 0; - ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; - R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); - if (R && !R->isZero()) - return pred; - pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; - R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); - if (R && !R->isZero()) - return pred; - pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; - R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); - if (R && !R->isZero()) - return pred; - - // If we couldn't figure it out, bail. - return ICmpInst::BAD_ICMP_PREDICATE; - } - - // If the first operand is simple, swap operands. - ICmpInst::Predicate SwappedRelation = - evaluateICmpRelation(V2, V1, isSigned); - if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) - return ICmpInst::getSwappedPredicate(SwappedRelation); - - } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) { - if (isa<ConstantExpr>(V2)) { // Swap as necessary. - ICmpInst::Predicate SwappedRelation = - evaluateICmpRelation(V2, V1, isSigned); - if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) - return ICmpInst::getSwappedPredicate(SwappedRelation); - return ICmpInst::BAD_ICMP_PREDICATE; - } - - // Now we know that the RHS is a GlobalValue, BlockAddress or simple - // constant (which, since the types must match, means that it's a - // ConstantPointerNull). - if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { - // Don't try to decide equality of aliases. - if (!isa<GlobalAlias>(GV) && !isa<GlobalAlias>(GV2)) - if (!GV->hasExternalWeakLinkage() || !GV2->hasExternalWeakLinkage()) - return ICmpInst::ICMP_NE; - } else if (isa<BlockAddress>(V2)) { - return ICmpInst::ICMP_NE; // Globals never equal labels. - } else { - assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); - // GlobalVals can never be null unless they have external weak linkage. - // We don't try to evaluate aliases here. - if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV)) - return ICmpInst::ICMP_NE; - } - } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) { - if (isa<ConstantExpr>(V2)) { // Swap as necessary. - ICmpInst::Predicate SwappedRelation = - evaluateICmpRelation(V2, V1, isSigned); - if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) - return ICmpInst::getSwappedPredicate(SwappedRelation); - return ICmpInst::BAD_ICMP_PREDICATE; - } - - // Now we know that the RHS is a GlobalValue, BlockAddress or simple - // constant (which, since the types must match, means that it is a - // ConstantPointerNull). - if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) { - // Block address in another function can't equal this one, but block - // addresses in the current function might be the same if blocks are - // empty. - if (BA2->getFunction() != BA->getFunction()) - return ICmpInst::ICMP_NE; - } else { - // Block addresses aren't null, don't equal the address of globals. - assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) && - "Canonicalization guarantee!"); - return ICmpInst::ICMP_NE; - } - } else { - // Ok, the LHS is known to be a constantexpr. The RHS can be any of a - // constantexpr, a global, block address, or a simple constant. - ConstantExpr *CE1 = cast<ConstantExpr>(V1); - Constant *CE1Op0 = CE1->getOperand(0); - - switch (CE1->getOpcode()) { - case Instruction::Trunc: - case Instruction::FPTrunc: - case Instruction::FPExt: - case Instruction::FPToUI: - case Instruction::FPToSI: - break; // We can't evaluate floating point casts or truncations. - - case Instruction::UIToFP: - case Instruction::SIToFP: - case Instruction::BitCast: - case Instruction::ZExt: - case Instruction::SExt: - // If the cast is not actually changing bits, and the second operand is a - // null pointer, do the comparison with the pre-casted value. - if (V2->isNullValue() && - (CE1->getType()->isPointerTy() || CE1->getType()->isIntegerTy())) { - if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; - if (CE1->getOpcode() == Instruction::SExt) isSigned = true; - return evaluateICmpRelation(CE1Op0, - Constant::getNullValue(CE1Op0->getType()), - isSigned); - } - break; - - case Instruction::GetElementPtr: - // Ok, since this is a getelementptr, we know that the constant has a - // pointer type. Check the various cases. - if (isa<ConstantPointerNull>(V2)) { - // If we are comparing a GEP to a null pointer, check to see if the base - // of the GEP equals the null pointer. - if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { - if (GV->hasExternalWeakLinkage()) - // Weak linkage GVals could be zero or not. We're comparing that - // to null pointer so its greater-or-equal - return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; - else - // If its not weak linkage, the GVal must have a non-zero address - // so the result is greater-than - return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; - } else if (isa<ConstantPointerNull>(CE1Op0)) { - // If we are indexing from a null pointer, check to see if we have any - // non-zero indices. - for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) - if (!CE1->getOperand(i)->isNullValue()) - // Offsetting from null, must not be equal. - return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; - // Only zero indexes from null, must still be zero. - return ICmpInst::ICMP_EQ; - } - // Otherwise, we can't really say if the first operand is null or not. - } else if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { - if (isa<ConstantPointerNull>(CE1Op0)) { - if (GV2->hasExternalWeakLinkage()) - // Weak linkage GVals could be zero or not. We're comparing it to - // a null pointer, so its less-or-equal - return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; - else - // If its not weak linkage, the GVal must have a non-zero address - // so the result is less-than - return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; - } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { - if (GV == GV2) { - // If this is a getelementptr of the same global, then it must be - // different. Because the types must match, the getelementptr could - // only have at most one index, and because we fold getelementptr's - // with a single zero index, it must be nonzero. - assert(CE1->getNumOperands() == 2 && - !CE1->getOperand(1)->isNullValue() && - "Surprising getelementptr!"); - return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; - } else { - // If they are different globals, we don't know what the value is, - // but they can't be equal. - return ICmpInst::ICMP_NE; - } - } - } else { - ConstantExpr *CE2 = cast<ConstantExpr>(V2); - Constant *CE2Op0 = CE2->getOperand(0); - - // There are MANY other foldings that we could perform here. They will - // probably be added on demand, as they seem needed. - switch (CE2->getOpcode()) { - default: break; - case Instruction::GetElementPtr: - // By far the most common case to handle is when the base pointers are - // obviously to the same or different globals. - if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { - if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal - return ICmpInst::ICMP_NE; - // Ok, we know that both getelementptr instructions are based on the - // same global. From this, we can precisely determine the relative - // ordering of the resultant pointers. - unsigned i = 1; - - // The logic below assumes that the result of the comparison - // can be determined by finding the first index that differs. - // This doesn't work if there is over-indexing in any - // subsequent indices, so check for that case first. - if (!CE1->isGEPWithNoNotionalOverIndexing() || - !CE2->isGEPWithNoNotionalOverIndexing()) - return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. - - // Compare all of the operands the GEP's have in common. - gep_type_iterator GTI = gep_type_begin(CE1); - for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); - ++i, ++GTI) - switch (IdxCompare(CE1->getOperand(i), - CE2->getOperand(i), GTI.getIndexedType())) { - case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; - case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; - case -2: return ICmpInst::BAD_ICMP_PREDICATE; - } - - // Ok, we ran out of things they have in common. If any leftovers - // are non-zero then we have a difference, otherwise we are equal. - for (; i < CE1->getNumOperands(); ++i) - if (!CE1->getOperand(i)->isNullValue()) { - if (isa<ConstantInt>(CE1->getOperand(i))) - return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; - else - return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. - } - - for (; i < CE2->getNumOperands(); ++i) - if (!CE2->getOperand(i)->isNullValue()) { - if (isa<ConstantInt>(CE2->getOperand(i))) - return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; - else - return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. - } - return ICmpInst::ICMP_EQ; - } - } - } - default: - break; - } - } - - return ICmpInst::BAD_ICMP_PREDICATE; -} - -Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred, - Constant *C1, Constant *C2) { - Type *ResultTy; - if (VectorType *VT = dyn_cast<VectorType>(C1->getType())) - ResultTy = VectorType::get(Type::getInt1Ty(C1->getContext()), - VT->getNumElements()); - else - ResultTy = Type::getInt1Ty(C1->getContext()); - - // Fold FCMP_FALSE/FCMP_TRUE unconditionally. - if (pred == FCmpInst::FCMP_FALSE) - return Constant::getNullValue(ResultTy); - - if (pred == FCmpInst::FCMP_TRUE) - return Constant::getAllOnesValue(ResultTy); - - // Handle some degenerate cases first - if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { - // For EQ and NE, we can always pick a value for the undef to make the - // predicate pass or fail, so we can return undef. - // Also, if both operands are undef, we can return undef. - if (ICmpInst::isEquality(ICmpInst::Predicate(pred)) || - (isa<UndefValue>(C1) && isa<UndefValue>(C2))) - return UndefValue::get(ResultTy); - // Otherwise, pick the same value as the non-undef operand, and fold - // it to true or false. - return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(pred)); - } - - // icmp eq/ne(null,GV) -> false/true - if (C1->isNullValue()) { - if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) - // Don't try to evaluate aliases. External weak GV can be null. - if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { - if (pred == ICmpInst::ICMP_EQ) - return ConstantInt::getFalse(C1->getContext()); - else if (pred == ICmpInst::ICMP_NE) - return ConstantInt::getTrue(C1->getContext()); - } - // icmp eq/ne(GV,null) -> false/true - } else if (C2->isNullValue()) { - if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) - // Don't try to evaluate aliases. External weak GV can be null. - if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { - if (pred == ICmpInst::ICMP_EQ) - return ConstantInt::getFalse(C1->getContext()); - else if (pred == ICmpInst::ICMP_NE) - return ConstantInt::getTrue(C1->getContext()); - } - } - - // If the comparison is a comparison between two i1's, simplify it. - if (C1->getType()->isIntegerTy(1)) { - switch(pred) { - case ICmpInst::ICMP_EQ: - if (isa<ConstantInt>(C2)) - return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2)); - return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2); - case ICmpInst::ICMP_NE: - return ConstantExpr::getXor(C1, C2); - default: - break; - } - } - - if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { - APInt V1 = cast<ConstantInt>(C1)->getValue(); - APInt V2 = cast<ConstantInt>(C2)->getValue(); - switch (pred) { - default: llvm_unreachable("Invalid ICmp Predicate"); - case ICmpInst::ICMP_EQ: return ConstantInt::get(ResultTy, V1 == V2); - case ICmpInst::ICMP_NE: return ConstantInt::get(ResultTy, V1 != V2); - case ICmpInst::ICMP_SLT: return ConstantInt::get(ResultTy, V1.slt(V2)); - case ICmpInst::ICMP_SGT: return ConstantInt::get(ResultTy, V1.sgt(V2)); - case ICmpInst::ICMP_SLE: return ConstantInt::get(ResultTy, V1.sle(V2)); - case ICmpInst::ICMP_SGE: return ConstantInt::get(ResultTy, V1.sge(V2)); - case ICmpInst::ICMP_ULT: return ConstantInt::get(ResultTy, V1.ult(V2)); - case ICmpInst::ICMP_UGT: return ConstantInt::get(ResultTy, V1.ugt(V2)); - case ICmpInst::ICMP_ULE: return ConstantInt::get(ResultTy, V1.ule(V2)); - case ICmpInst::ICMP_UGE: return ConstantInt::get(ResultTy, V1.uge(V2)); - } - } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { - APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); - APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); - APFloat::cmpResult R = C1V.compare(C2V); - switch (pred) { - default: llvm_unreachable("Invalid FCmp Predicate"); - case FCmpInst::FCMP_FALSE: return Constant::getNullValue(ResultTy); - case FCmpInst::FCMP_TRUE: return Constant::getAllOnesValue(ResultTy); - case FCmpInst::FCMP_UNO: - return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered); - case FCmpInst::FCMP_ORD: - return ConstantInt::get(ResultTy, R!=APFloat::cmpUnordered); - case FCmpInst::FCMP_UEQ: - return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || - R==APFloat::cmpEqual); - case FCmpInst::FCMP_OEQ: - return ConstantInt::get(ResultTy, R==APFloat::cmpEqual); - case FCmpInst::FCMP_UNE: - return ConstantInt::get(ResultTy, R!=APFloat::cmpEqual); - case FCmpInst::FCMP_ONE: - return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || - R==APFloat::cmpGreaterThan); - case FCmpInst::FCMP_ULT: - return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || - R==APFloat::cmpLessThan); - case FCmpInst::FCMP_OLT: - return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan); - case FCmpInst::FCMP_UGT: - return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || - R==APFloat::cmpGreaterThan); - case FCmpInst::FCMP_OGT: - return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan); - case FCmpInst::FCMP_ULE: - return ConstantInt::get(ResultTy, R!=APFloat::cmpGreaterThan); - case FCmpInst::FCMP_OLE: - return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || - R==APFloat::cmpEqual); - case FCmpInst::FCMP_UGE: - return ConstantInt::get(ResultTy, R!=APFloat::cmpLessThan); - case FCmpInst::FCMP_OGE: - return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan || - R==APFloat::cmpEqual); - } - } else if (C1->getType()->isVectorTy()) { - // If we can constant fold the comparison of each element, constant fold - // the whole vector comparison. - SmallVector<Constant*, 4> ResElts; - Type *Ty = IntegerType::get(C1->getContext(), 32); - // Compare the elements, producing an i1 result or constant expr. - for (unsigned i = 0, e = C1->getType()->getVectorNumElements(); i != e;++i){ - Constant *C1E = - ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, i)); - Constant *C2E = - ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, i)); - - ResElts.push_back(ConstantExpr::getCompare(pred, C1E, C2E)); - } - - return ConstantVector::get(ResElts); - } - - if (C1->getType()->isFloatingPointTy()) { - int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. - switch (evaluateFCmpRelation(C1, C2)) { - default: llvm_unreachable("Unknown relation!"); - case FCmpInst::FCMP_UNO: - case FCmpInst::FCMP_ORD: - case FCmpInst::FCMP_UEQ: - case FCmpInst::FCMP_UNE: - case FCmpInst::FCMP_ULT: - case FCmpInst::FCMP_UGT: - case FCmpInst::FCMP_ULE: - case FCmpInst::FCMP_UGE: - case FCmpInst::FCMP_TRUE: - case FCmpInst::FCMP_FALSE: - case FCmpInst::BAD_FCMP_PREDICATE: - break; // Couldn't determine anything about these constants. - case FCmpInst::FCMP_OEQ: // We know that C1 == C2 - Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || - pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || - pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); - break; - case FCmpInst::FCMP_OLT: // We know that C1 < C2 - Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || - pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || - pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); - break; - case FCmpInst::FCMP_OGT: // We know that C1 > C2 - Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || - pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || - pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); - break; - case FCmpInst::FCMP_OLE: // We know that C1 <= C2 - // We can only partially decide this relation. - if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) - Result = 0; - else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) - Result = 1; - break; - case FCmpInst::FCMP_OGE: // We known that C1 >= C2 - // We can only partially decide this relation. - if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) - Result = 0; - else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) - Result = 1; - break; - case FCmpInst::FCMP_ONE: // We know that C1 != C2 - // We can only partially decide this relation. - if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) - Result = 0; - else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) - Result = 1; - break; - } - - // If we evaluated the result, return it now. - if (Result != -1) - return ConstantInt::get(ResultTy, Result); - - } else { - // Evaluate the relation between the two constants, per the predicate. - int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. - switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) { - default: llvm_unreachable("Unknown relational!"); - case ICmpInst::BAD_ICMP_PREDICATE: - break; // Couldn't determine anything about these constants. - case ICmpInst::ICMP_EQ: // We know the constants are equal! - // If we know the constants are equal, we can decide the result of this - // computation precisely. - Result = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred); - break; - case ICmpInst::ICMP_ULT: - switch (pred) { - case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE: - Result = 1; break; - case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE: - Result = 0; break; - } - break; - case ICmpInst::ICMP_SLT: - switch (pred) { - case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE: - Result = 1; break; - case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE: - Result = 0; break; - } - break; - case ICmpInst::ICMP_UGT: - switch (pred) { - case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE: - Result = 1; break; - case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE: - Result = 0; break; - } - break; - case ICmpInst::ICMP_SGT: - switch (pred) { - case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE: - Result = 1; break; - case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE: - Result = 0; break; - } - break; - case ICmpInst::ICMP_ULE: - if (pred == ICmpInst::ICMP_UGT) Result = 0; - if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1; - break; - case ICmpInst::ICMP_SLE: - if (pred == ICmpInst::ICMP_SGT) Result = 0; - if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1; - break; - case ICmpInst::ICMP_UGE: - if (pred == ICmpInst::ICMP_ULT) Result = 0; - if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1; - break; - case ICmpInst::ICMP_SGE: - if (pred == ICmpInst::ICMP_SLT) Result = 0; - if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1; - break; - case ICmpInst::ICMP_NE: - if (pred == ICmpInst::ICMP_EQ) Result = 0; - if (pred == ICmpInst::ICMP_NE) Result = 1; - break; - } - - // If we evaluated the result, return it now. - if (Result != -1) - return ConstantInt::get(ResultTy, Result); - - // If the right hand side is a bitcast, try using its inverse to simplify - // it by moving it to the left hand side. We can't do this if it would turn - // a vector compare into a scalar compare or visa versa. - if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) { - Constant *CE2Op0 = CE2->getOperand(0); - if (CE2->getOpcode() == Instruction::BitCast && - CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy()) { - Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType()); - return ConstantExpr::getICmp(pred, Inverse, CE2Op0); - } - } - - // If the left hand side is an extension, try eliminating it. - if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { - if ((CE1->getOpcode() == Instruction::SExt && ICmpInst::isSigned(pred)) || - (CE1->getOpcode() == Instruction::ZExt && !ICmpInst::isSigned(pred))){ - Constant *CE1Op0 = CE1->getOperand(0); - Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType()); - if (CE1Inverse == CE1Op0) { - // Check whether we can safely truncate the right hand side. - Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType()); - if (ConstantExpr::getZExt(C2Inverse, C2->getType()) == C2) { - return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse); - } - } - } - } - - if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) || - (C1->isNullValue() && !C2->isNullValue())) { - // If C2 is a constant expr and C1 isn't, flip them around and fold the - // other way if possible. - // Also, if C1 is null and C2 isn't, flip them around. - pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); - return ConstantExpr::getICmp(pred, C2, C1); - } - } - return 0; -} - -/// isInBoundsIndices - Test whether the given sequence of *normalized* indices -/// is "inbounds". -template<typename IndexTy> -static bool isInBoundsIndices(ArrayRef<IndexTy> Idxs) { - // No indices means nothing that could be out of bounds. - if (Idxs.empty()) return true; - - // If the first index is zero, it's in bounds. - if (cast<Constant>(Idxs[0])->isNullValue()) return true; - - // If the first index is one and all the rest are zero, it's in bounds, - // by the one-past-the-end rule. - if (!cast<ConstantInt>(Idxs[0])->isOne()) - return false; - for (unsigned i = 1, e = Idxs.size(); i != e; ++i) - if (!cast<Constant>(Idxs[i])->isNullValue()) - return false; - return true; -} - -template<typename IndexTy> -static Constant *ConstantFoldGetElementPtrImpl(Constant *C, - bool inBounds, - ArrayRef<IndexTy> Idxs) { - if (Idxs.empty()) return C; - Constant *Idx0 = cast<Constant>(Idxs[0]); - if ((Idxs.size() == 1 && Idx0->isNullValue())) - return C; - - if (isa<UndefValue>(C)) { - PointerType *Ptr = cast<PointerType>(C->getType()); - Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs); - assert(Ty != 0 && "Invalid indices for GEP!"); - return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); - } - - if (C->isNullValue()) { - bool isNull = true; - for (unsigned i = 0, e = Idxs.size(); i != e; ++i) - if (!cast<Constant>(Idxs[i])->isNullValue()) { - isNull = false; - break; - } - if (isNull) { - PointerType *Ptr = cast<PointerType>(C->getType()); - Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs); - assert(Ty != 0 && "Invalid indices for GEP!"); - return ConstantPointerNull::get(PointerType::get(Ty, - Ptr->getAddressSpace())); - } - } - - if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { - // Combine Indices - If the source pointer to this getelementptr instruction - // is a getelementptr instruction, combine the indices of the two - // getelementptr instructions into a single instruction. - // - if (CE->getOpcode() == Instruction::GetElementPtr) { - Type *LastTy = 0; - for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); - I != E; ++I) - LastTy = *I; - - if ((LastTy && isa<SequentialType>(LastTy)) || Idx0->isNullValue()) { - SmallVector<Value*, 16> NewIndices; - NewIndices.reserve(Idxs.size() + CE->getNumOperands()); - for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) - NewIndices.push_back(CE->getOperand(i)); - - // Add the last index of the source with the first index of the new GEP. - // Make sure to handle the case when they are actually different types. - Constant *Combined = CE->getOperand(CE->getNumOperands()-1); - // Otherwise it must be an array. - if (!Idx0->isNullValue()) { - Type *IdxTy = Combined->getType(); - if (IdxTy != Idx0->getType()) { - Type *Int64Ty = Type::getInt64Ty(IdxTy->getContext()); - Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Int64Ty); - Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, Int64Ty); - Combined = ConstantExpr::get(Instruction::Add, C1, C2); - } else { - Combined = - ConstantExpr::get(Instruction::Add, Idx0, Combined); - } - } - - NewIndices.push_back(Combined); - NewIndices.append(Idxs.begin() + 1, Idxs.end()); - return - ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices, - inBounds && - cast<GEPOperator>(CE)->isInBounds()); - } - } - - // Implement folding of: - // i32* getelementptr ([2 x i32]* bitcast ([3 x i32]* %X to [2 x i32]*), - // i64 0, i64 0) - // To: i32* getelementptr ([3 x i32]* %X, i64 0, i64 0) - // - if (CE->isCast() && Idxs.size() > 1 && Idx0->isNullValue()) { - if (PointerType *SPT = - dyn_cast<PointerType>(CE->getOperand(0)->getType())) - if (ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType())) - if (ArrayType *CAT = - dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType())) - if (CAT->getElementType() == SAT->getElementType()) - return - ConstantExpr::getGetElementPtr((Constant*)CE->getOperand(0), - Idxs, inBounds); - } - } - - // Check to see if any array indices are not within the corresponding - // notional array bounds. If so, try to determine if they can be factored - // out into preceding dimensions. - bool Unknown = false; - SmallVector<Constant *, 8> NewIdxs; - Type *Ty = C->getType(); - Type *Prev = 0; - for (unsigned i = 0, e = Idxs.size(); i != e; - Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) { - if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) { - if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) - if (ATy->getNumElements() <= INT64_MAX && - ATy->getNumElements() != 0 && - CI->getSExtValue() >= (int64_t)ATy->getNumElements()) { - if (isa<SequentialType>(Prev)) { - // It's out of range, but we can factor it into the prior - // dimension. - NewIdxs.resize(Idxs.size()); - ConstantInt *Factor = ConstantInt::get(CI->getType(), - ATy->getNumElements()); - NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); - - Constant *PrevIdx = cast<Constant>(Idxs[i-1]); - Constant *Div = ConstantExpr::getSDiv(CI, Factor); - - // Before adding, extend both operands to i64 to avoid - // overflow trouble. - if (!PrevIdx->getType()->isIntegerTy(64)) - PrevIdx = ConstantExpr::getSExt(PrevIdx, - Type::getInt64Ty(Div->getContext())); - if (!Div->getType()->isIntegerTy(64)) - Div = ConstantExpr::getSExt(Div, - Type::getInt64Ty(Div->getContext())); - - NewIdxs[i-1] = ConstantExpr::getAdd(PrevIdx, Div); - } else { - // It's out of range, but the prior dimension is a struct - // so we can't do anything about it. - Unknown = true; - } - } - } else { - // We don't know if it's in range or not. - Unknown = true; - } - } - - // If we did any factoring, start over with the adjusted indices. - if (!NewIdxs.empty()) { - for (unsigned i = 0, e = Idxs.size(); i != e; ++i) - if (!NewIdxs[i]) NewIdxs[i] = cast<Constant>(Idxs[i]); - return ConstantExpr::getGetElementPtr(C, NewIdxs, inBounds); - } - - // If all indices are known integers and normalized, we can do a simple - // check for the "inbounds" property. - if (!Unknown && !inBounds && - isa<GlobalVariable>(C) && isInBoundsIndices(Idxs)) - return ConstantExpr::getInBoundsGetElementPtr(C, Idxs); - - return 0; -} - -Constant *llvm::ConstantFoldGetElementPtr(Constant *C, - bool inBounds, - ArrayRef<Constant *> Idxs) { - return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); -} - -Constant *llvm::ConstantFoldGetElementPtr(Constant *C, - bool inBounds, - ArrayRef<Value *> Idxs) { - return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); -} |
