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[GlobalISel][Legalizer] Convert the FP constants to the right APFloat type for G_FCONSTANT.

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We weren't converting the immediate ConstantFP during legalization, which caused
the wrong bit patterns to be emitted for half type FP constants.

Fixes PR36106.

llvm-svn: 323582
This commit is contained in:
Amara Emerson 2018-01-27 07:07:20 +00:00
parent a33bd832ed
commit 8d65a6ec7e
2 changed files with 19 additions and 2 deletions
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19
lib/CodeGen/GlobalISel/LegalizerHelper.cpp
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@ -715,7 +715,24 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
}
case TargetOpcode::G_FCONSTANT: {
unsigned DstExt = MRI.createGenericVirtualRegister(WideTy);
MIRBuilder.buildFConstant(DstExt, *MI.getOperand(1).getFPImm());
const ConstantFP *CFP = MI.getOperand(1).getFPImm();
APFloat Val = CFP->getValueAPF();
LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
auto LLT2Sem = [](LLT Ty) {
switch (Ty.getSizeInBits()) {
case 32:
return &APFloat::IEEEsingle();
break;
case 64:
return &APFloat::IEEEdouble();
break;
default:
llvm_unreachable("Unhandled fp widen type");
}
};
bool LosesInfo;
Val.convert(*LLT2Sem(WideTy), APFloat::rmTowardZero, &LosesInfo);
MIRBuilder.buildFConstant(DstExt, *ConstantFP::get(Ctx, Val));
MIRBuilder.buildFPTrunc(MI.getOperand(0).getReg(), DstExt);
MI.eraseFromParent();
return Legalized;

2
test/CodeGen/AArch64/GlobalISel/legalize-constant.mir
View File

@ -75,7 +75,7 @@ body: |
; CHECK: %w0 = COPY [[C]](s32)
; CHECK: [[C1:%[0-9]+]]:_(s64) = G_FCONSTANT double 2.000000e+00
; CHECK: %x0 = COPY [[C1]](s64)
; CHECK: [[C2:%[0-9]+]]:_(s32) = G_FCONSTANT half 0xH0000
; CHECK: [[C2:%[0-9]+]]:_(s32) = G_FCONSTANT float 0.000000e+00
; CHECK: [[FPTRUNC:%[0-9]+]]:_(s16) = G_FPTRUNC [[C2]](s32)
; CHECK: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[FPTRUNC]](s16)
; CHECK: %w0 = COPY [[ANYEXT]](s32)