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FP16 constfolding

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98911 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Anton Korobeynikov 2010-03-19 00:36:35 +00:00
parent f65027842e
commit faa75f6e47
1 changed files with 25 additions and 0 deletions
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25
lib/Analysis/ConstantFolding.cpp
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@ -994,6 +994,8 @@ llvm::canConstantFoldCallTo(const Function *F) {
case Intrinsic::usub_with_overflow:
case Intrinsic::sadd_with_overflow:
case Intrinsic::ssub_with_overflow:
case Intrinsic::convert_from_fp16:
case Intrinsic::convert_to_fp16:
return true;
default:
return false;
@ -1074,6 +1076,15 @@ llvm::ConstantFoldCall(Function *F,
const Type *Ty = F->getReturnType();
if (NumOperands == 1) {
if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
if (Name == "llvm.convert.to.fp16") {
APFloat Val(Op->getValueAPF());
bool lost = false;
Val.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &lost);
return ConstantInt::get(F->getContext(), Val.bitcastToAPInt());
}
if (!Ty->isFloatTy() && !Ty->isDoubleTy())
return 0;
/// Currently APFloat versions of these functions do not exist, so we use
@ -1158,6 +1169,20 @@ llvm::ConstantFoldCall(Function *F,
return ConstantInt::get(Ty, Op->getValue().countTrailingZeros());
else if (Name.startswith("llvm.ctlz"))
return ConstantInt::get(Ty, Op->getValue().countLeadingZeros());
else if (Name == "llvm.convert.from.fp16") {
APFloat Val(Op->getValue());
bool lost = false;
APFloat::opStatus status =
Val.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven, &lost);
// Conversion is always precise.
status = status;
assert(status == APFloat::opOK && !lost &&
"Precision lost during fp16 constfolding");
return ConstantFP::get(F->getContext(), Val);
}
return 0;
}