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GlobalISel: Restrict narrow scalar for fptoui/fptosi results 

This practically only works for the f16 case AMDGPU uses, not wider
types.

Fixes bug 49710 by failing legalization.
This commit is contained in:
Matt Arsenault 2021-03-26 17:29:36 -04:00
parent 8fbe04f46b
commit 83a25a1010
3 changed files with 57 additions and 16 deletions
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1
llvm/include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
View File

@ -330,6 +330,7 @@ public:
LegalizeResult narrowScalarAddSub(MachineInstr &MI, unsigned TypeIdx,
LLT NarrowTy);
LegalizeResult narrowScalarMul(MachineInstr &MI, LLT Ty);
LegalizeResult narrowScalarFPTOI(MachineInstr &MI, unsigned TypeIdx, LLT Ty);
LegalizeResult narrowScalarExtract(MachineInstr &MI, unsigned TypeIdx, LLT Ty);
LegalizeResult narrowScalarInsert(MachineInstr &MI, unsigned TypeIdx, LLT Ty);

44
llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
View File

@ -1216,22 +1216,9 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
Observer.changedInstr(MI);
return Legalized;
}
case TargetOpcode::G_FPTOUI: {
if (TypeIdx != 0)
return UnableToLegalize;
Observer.changingInstr(MI);
narrowScalarDst(MI, NarrowTy, 0, TargetOpcode::G_ZEXT);
Observer.changedInstr(MI);
return Legalized;
}
case TargetOpcode::G_FPTOSI: {
if (TypeIdx != 0)
return UnableToLegalize;
Observer.changingInstr(MI);
narrowScalarDst(MI, NarrowTy, 0, TargetOpcode::G_SEXT);
Observer.changedInstr(MI);
return Legalized;
}
case TargetOpcode::G_FPTOUI:
case TargetOpcode::G_FPTOSI:
return narrowScalarFPTOI(MI, TypeIdx, NarrowTy);
case TargetOpcode::G_FPEXT:
if (TypeIdx != 0)
return UnableToLegalize;
@ -4846,6 +4833,31 @@ LegalizerHelper::narrowScalarMul(MachineInstr &MI, LLT NarrowTy) {
return Legalized;
}
LegalizerHelper::LegalizeResult
LegalizerHelper::narrowScalarFPTOI(MachineInstr &MI, unsigned TypeIdx,
LLT NarrowTy) {
if (TypeIdx != 0)
return UnableToLegalize;
bool IsSigned = MI.getOpcode() == TargetOpcode::G_FPTOSI;
Register Src = MI.getOperand(1).getReg();
LLT SrcTy = MRI.getType(Src);
// If all finite floats fit into the narrowed integer type, we can just swap
// out the result type. This is practically only useful for conversions from
// half to at least 16-bits, so just handle the one case.
if (SrcTy.getScalarType() != LLT::scalar(16) ||
NarrowTy.getScalarSizeInBits() < (IsSigned ? 17 : 16))
return UnableToLegalize;
Observer.changingInstr(MI);
narrowScalarDst(MI, NarrowTy, 0,
IsSigned ? TargetOpcode::G_SEXT : TargetOpcode::G_ZEXT);
Observer.changedInstr(MI);
return Legalized;
}
LegalizerHelper::LegalizeResult
LegalizerHelper::narrowScalarExtract(MachineInstr &MI, unsigned TypeIdx,
LLT NarrowTy) {

28
llvm/test/CodeGen/AArch64/GlobalISel/legalize-fptoi.mir
View File

@ -238,3 +238,31 @@ body: |
%1:_(<4 x s32>) = G_FPTOSI %0
$q0 = COPY %1
...
---
name: test_fptoui_s128_s32
body: |
bb.0:
liveins: $w0
; CHECK-LABEL: name: test_fptoui_s128_s32
; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $w0
; CHECK: [[FPTOUI:%[0-9]+]]:_(s128) = G_FPTOUI [[COPY]](s32)
; CHECK: $q0 = COPY [[FPTOUI]](s128)
%0:_(s32) = COPY $w0
%1:_(s128) = G_FPTOUI %0
$q0 = COPY %1
...
---
name: test_fptosi_s128_s32
body: |
bb.0:
liveins: $w0
; CHECK-LABEL: name: test_fptosi_s128_s32
; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $w0
; CHECK: [[FPTOSI:%[0-9]+]]:_(s128) = G_FPTOSI [[COPY]](s32)
; CHECK: $q0 = COPY [[FPTOSI]](s128)
%0:_(s32) = COPY $w0
%1:_(s128) = G_FPTOSI %0
$q0 = COPY %1
...