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[GlobalISel] fix crash in narrowScalarExtract if DstRegs only has one register 

Summary: When narrowing a scalar G_EXTRACT where the destination lines up perfectly with a single result of the emitted G_UNMERGE_VALUES a COPY should be emitted instead of unconditionally trying to emit a G_MERGE_VALUES.

Reviewers: arsenm, dsanders

Reviewed By: arsenm

Subscribers: wdng, rovka, hiraditya, volkan, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75743
This commit is contained in:
Dominik Montada 2020-03-12 09:03:08 +01:00
parent 4327a9b46b
commit 6b96623dcb
2 changed files with 43 additions and 2 deletions
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4
llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
View File

@ -3705,8 +3705,10 @@ LegalizerHelper::narrowScalarExtract(MachineInstr &MI, unsigned TypeIdx,
Register DstReg = MI.getOperand(0).getReg(); Register DstReg = MI.getOperand(0).getReg();
if (MRI.getType(DstReg).isVector()) if (MRI.getType(DstReg).isVector())
MIRBuilder.buildBuildVector(DstReg, DstRegs); MIRBuilder.buildBuildVector(DstReg, DstRegs);
else else if (DstRegs.size() > 1)
MIRBuilder.buildMerge(DstReg, DstRegs); MIRBuilder.buildMerge(DstReg, DstRegs);
else
MIRBuilder.buildCopy(DstReg, DstRegs[0]);
MI.eraseFromParent(); MI.eraseFromParent();
return Legalized; return Legalized;
} }

39
llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp
View File

@ -2302,4 +2302,43 @@ TEST_F(GISelMITest, LibcallFNearbyInt) {
// Check // Check
EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF; EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF;
} }
TEST_F(GISelMITest, NarrowScalarExtract) {
setUp();
if (!TM)
return;
// Declare your legalization info
DefineLegalizerInfo(A, {
getActionDefinitionsBuilder(G_UNMERGE_VALUES).legalFor({{s32, s64}});
getActionDefinitionsBuilder(G_EXTRACT).legalFor({{s16, s32}});
});
LLT S16{LLT::scalar(16)};
LLT S32{LLT::scalar(32)};
auto MIBExtractS32 = B.buildExtract(S32, Copies[1], 32);
auto MIBExtractS16 = B.buildExtract(S16, Copies[1], 0);
AInfo Info(MF->getSubtarget());
DummyGISelObserver Observer;
LegalizerHelper Helper(*MF, Info, Observer, B);
EXPECT_EQ(LegalizerHelper::LegalizeResult::Legalized,
Helper.narrowScalar(*MIBExtractS32, 1, S32));
EXPECT_EQ(LegalizerHelper::LegalizeResult::Legalized,
Helper.narrowScalar(*MIBExtractS16, 1, S32));
const auto *CheckStr = R"(
CHECK: [[UV:%[0-9]+]]:_(s32), [[UV1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES
CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY [[UV1]]
CHECK: [[UV3:%[0-9]+]]:_(s32), [[UV4:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES
CHECK: [[EXTR:%[0-9]+]]:_(s16) = G_EXTRACT [[UV3]]:_(s32), 0
CHECK: [[COPY:%[0-9]+]]:_(s16) = COPY [[EXTR]]
)";
// Check
EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF;
}
} // namespace } // namespace