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Implement casts.ll:test26: a cast from float -> double -> integer, doesn't 

need the float->double part.

llvm-svn: 25452
This commit is contained in:
Chris Lattner 2006-01-19 07:40:22 +00:00
parent ef25927f4f
commit e154abf9b3
1 changed files with 11 additions and 2 deletions
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13
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -3799,8 +3799,8 @@ static CastType getCastType(const Type *Src, const Type *Dest) {
// isEliminableCastOfCast - Return true if it is valid to eliminate the CI
// instruction.
//
static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
const Type *DstTy, TargetData *TD) {
static bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
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
@ -3856,6 +3856,15 @@ static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
return ResultCast == FirstCast;
}
}
// If this is a cast from 'float -> double -> integer', cast from
// 'float -> integer' directly, as the value isn't changed by the
// float->double conversion.
if (SrcTy->isFloatingPoint() && MidTy->isFloatingPoint() &&
DstTy->isIntegral() &&
SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
return true;
return false;
}