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
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index c76a52a..48eb86c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -2650,12 +2650,15 @@
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;
}