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implement cast.ll:test35. With this, we recognize:

Browse Source 
unsigned short swp(unsigned short a) {
       return ((a & 0xff00) >> 8 | (a & 0x00ff) << 8);
}

as an idiom for bswap.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32011 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-11-29 07:18:39 +00:00
parent 6478b2fcd1
commit 46b96055cf
1 changed files with 16 additions and 0 deletions
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16
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -5624,6 +5624,14 @@ static bool CanEvaluateInDifferentType(Value *V, const Type *Ty,
// These operators can all arbitrarily be extended or truncated.
return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved) &&
CanEvaluateInDifferentType(I->getOperand(1), Ty, NumCastsRemoved);
case Instruction::AShr:
case Instruction::LShr:
case Instruction::Shl:
// If this is just a bitcast changing the sign of the operation, we can
// convert if the operand can be converted.
if (V->getType()->getPrimitiveSizeInBits() == Ty->getPrimitiveSizeInBits())
return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved);
break;
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
@ -5669,6 +5677,14 @@ Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty) {
LHS, RHS, I->getName());
break;
}
case Instruction::AShr:
case Instruction::LShr:
case Instruction::Shl: {
Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty);
Res = new ShiftInst((Instruction::OtherOps)I->getOpcode(), LHS,
I->getOperand(1), I->getName());
break;
}
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt: