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LegalizeDAG: make sure cast is unsigned before using FP_TO_UINT. 

It's valid to use FP_TO_SINT when asking for a smaller type (e.g. all
"unsigned int16" values fit into a "signed int32"), but the reverse
isn't true.

Unfortunately, I'm not actually aware of any architecture with
asymmetric FP_TO_SINT and FP_TO_UINT handling and the logic happens to
work in the symmetric case, so I can't actually write a test for this.

llvm-svn: 210986
This commit is contained in:
Tim Northover 2014-06-15 09:27:20 +00:00
parent dbecc3b3fc
commit 65277a2bc0
1 changed files with 4 additions and 1 deletions
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5
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -2650,12 +2650,15 @@ SDValue SelectionDAGLegalize::PromoteLegalFP_TO_INT(SDValue LegalOp,
NewOutTy = (MVT::SimpleValueType)(NewOutTy.getSimpleVT().SimpleTy+1);
assert(NewOutTy.isInteger() && "Ran out of possibilities!");
// A larger signed type can hold all unsigned values of the requested type,
// so using FP_TO_SINT is valid
if (TLI.isOperationLegalOrCustom(ISD::FP_TO_SINT, NewOutTy)) {
OpToUse = ISD::FP_TO_SINT;
break;
}
if (TLI.isOperationLegalOrCustom(ISD::FP_TO_UINT, NewOutTy)) {
// However, if the value may be < 0.0, we *must* use some FP_TO_SINT.
if (!isSigned && TLI.isOperationLegalOrCustom(ISD::FP_TO_UINT, NewOutTy)) {
OpToUse = ISD::FP_TO_UINT;
break;
}