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remove an xform subsumed by EvaluateInDifferentType.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93095 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-01-10 01:35:55 +00:00
parent 5c1735a4df
commit 3f7dc880c4
1 changed files with 0 additions and 27 deletions
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27
lib/Transforms/InstCombine/InstCombineCasts.cpp
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@ -953,33 +953,6 @@ Instruction *InstCombiner::visitSExt(SExtInst &CI) {
return SelectInst::Create(Src,
Constant::getAllOnesValue(CI.getType()),
Constant::getNullValue(CI.getType()));
// See if the value being truncated is already sign extended. If so, just
// eliminate the trunc/sext pair.
if (Operator::getOpcode(Src) == Instruction::Trunc) {
Value *Op = cast<User>(Src)->getOperand(0);
unsigned OpBits = Op->getType()->getScalarSizeInBits();
unsigned MidBits = SrcTy->getScalarSizeInBits();
unsigned DestBits = DestTy->getScalarSizeInBits();
unsigned NumSignBits = ComputeNumSignBits(Op);
if (OpBits == DestBits) {
// Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
// bits, it is already ready.
if (NumSignBits > DestBits-MidBits)
return ReplaceInstUsesWith(CI, Op);
} else if (OpBits < DestBits) {
// Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
// bits, just sext from i32.
if (NumSignBits > OpBits-MidBits)
return new SExtInst(Op, CI.getType(), "tmp");
} else {
// Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
// bits, just truncate to i32.
if (NumSignBits > OpBits-MidBits)
return new TruncInst(Op, CI.getType(), "tmp");
}
}
// Attempt to extend the entire input expression tree to the destination
// type. Only do this if the dest type is a simple type, don't convert the