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Implement Transforms/InstCombine/IntPtrCast.ll

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llvm-svn: 15029
This commit is contained in:
Chris Lattner 2004-07-20 05:21:00 +00:00
parent f6d78f81c0
commit f8c20caf25
1 changed files with 16 additions and 11 deletions
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27
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1966,7 +1966,7 @@ static CastType getCastType(const Type *Src, const Type *Dest) {
// instruction.
//
static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
const Type *DstTy) {
const Type *DstTy, TargetData *TD) {
// It is legal to eliminate the instruction if casting A->B->A if the sizes
// are identical and the bits don't get reinterpreted (for example
@ -1974,6 +1974,15 @@ static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
return true;
// If the source and destination types are pointer types, and the intermediate
// is an integer type bigger than a pointer, eliminate the casts.
if (isa<PointerType>(SrcTy) && isa<PointerType>(DstTy)) {
if (isa<PointerType>(MidTy)) return true;
if (MidTy->isInteger() && MidTy->getPrimitiveSize() >= TD->getPointerSize())
return true;
}
// Allow free casting and conversion of sizes as long as the sign doesn't
// change...
if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
@ -2010,18 +2019,14 @@ static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
return true;
}
}
// Otherwise, we cannot succeed. Specifically we do not want to allow things
// like: short -> ushort -> uint, because this can create wrong results if
// the input short is negative!
//
return false;
}
static bool ValueRequiresCast(const Value *V, const Type *Ty) {
static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
if (V->getType() == Ty || isa<Constant>(V)) return false;
if (const CastInst *CI = dyn_cast<CastInst>(V))
if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty))
if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
TD))
return false;
return true;
}
@ -2056,7 +2061,7 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
//
if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
CSrc->getType(), CI.getType())) {
CSrc->getType(), CI.getType(), TD)) {
// This instruction now refers directly to the cast's src operand. This
// has a good chance of making CSrc dead.
CI.setOperand(0, CSrc->getOperand(0));
@ -2153,8 +2158,8 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
// Don't insert two casts if they cannot be eliminated. We allow two
// casts to be inserted if the sizes are the same. This could only be
// converting signedness, which is a noop.
if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy) ||
!ValueRequiresCast(Op0, DestTy)) {
if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
!ValueRequiresCast(Op0, DestTy, TD)) {
Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
return BinaryOperator::create(cast<BinaryOperator>(SrcI)