+++ /dev/null
-//===- 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/ADT/SmallVector.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Function.h"
-#include "llvm/GlobalAlias.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/Instructions.h"
-#include "llvm/Operator.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);
-}
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