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GlobalISel: Handle more cases for widenScalar of G_MERGE_VALUES

Use an anyext to the requested type for the leftover operand to
produce a slightly wider type, and then truncate the final merge.

I have another implementation almost ready which handles arbitrary
widens, but I think it produces worse code in this example (which I
think is 90% due to not folding redundant copies or folding out
implicit_def users), so I wanted to add this as a baseline first.

llvm-svn: 366366
This commit is contained in:
Matt Arsenault 2019-07-17 20:22:38 +00:00
parent 26f466be75
commit 5d75c7a2b6
3 changed files with 118 additions and 4 deletions

View File

@ -875,10 +875,14 @@ LegalizerHelper::widenScalarMergeValues(MachineInstr &MI, unsigned TypeIdx,
// Try to turn this into a merge of merges if we can use the requested type as
// the source.
// TODO: Pad with undef if DstTy > WideTy
if (NumMerge > 1 && WideTy.getSizeInBits() % SrcTy.getSizeInBits() == 0) {
if (NumMerge > 1) {
int PartsPerMerge = WideTy.getSizeInBits() / SrcTy.getSizeInBits();
if (WideTy.getSizeInBits() % SrcTy.getSizeInBits() != 0)
return UnableToLegalize;
int RemainderBits = DstTy.getSizeInBits() % WideTy.getSizeInBits();
int RemainderParts = RemainderBits / SrcTy.getSizeInBits();
SmallVector<Register, 4> Parts;
SmallVector<Register, 4> SubMerges;
@ -891,11 +895,26 @@ LegalizerHelper::widenScalarMergeValues(MachineInstr &MI, unsigned TypeIdx,
Parts.clear();
}
if (RemainderParts == 0) {
MIRBuilder.buildMerge(DstReg, SubMerges);
MI.eraseFromParent();
return Legalized;
}
assert(RemainderParts == 1);
auto AnyExt = MIRBuilder.buildAnyExt(
WideTy, MI.getOperand(MI.getNumOperands() - 1).getReg());
SubMerges.push_back(AnyExt.getReg(0));
LLT WiderDstTy = LLT::scalar(SubMerges.size() * WideTy.getSizeInBits());
auto Merge = MIRBuilder.buildMerge(WiderDstTy, SubMerges);
MIRBuilder.buildTrunc(DstReg, Merge);
MI.eraseFromParent();
return Legalized;
}
unsigned NumOps = MI.getNumOperands();
unsigned NumSrc = MI.getNumOperands() - 1;
unsigned PartSize = DstTy.getSizeInBits() / NumSrc;

View File

@ -535,3 +535,64 @@ body: |
%8:_(s96) = G_MERGE_VALUES %0, %1, %2, %3, %4, %5
$vgpr0_vgpr1_vgpr2 = COPY %8
...
---
name: test_merge_s56_s8_s8_s8_s8_s8_s8_s8
body: |
bb.0:
; CHECK-LABEL: name: test_merge_s56_s8_s8_s8_s8_s8_s8_s8
; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
; CHECK: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 1
; CHECK: [[C2:%[0-9]+]]:_(s32) = G_CONSTANT i32 2
; CHECK: [[C3:%[0-9]+]]:_(s32) = G_CONSTANT i32 3
; CHECK: [[C4:%[0-9]+]]:_(s32) = G_CONSTANT i32 4
; CHECK: [[C5:%[0-9]+]]:_(s32) = G_CONSTANT i32 5
; CHECK: [[C6:%[0-9]+]]:_(s32) = G_CONSTANT i32 6
; CHECK: [[C7:%[0-9]+]]:_(s32) = G_CONSTANT i32 255
; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[C7]](s32)
; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[C]](s32)
; CHECK: [[AND:%[0-9]+]]:_(s16) = G_AND [[TRUNC1]], [[TRUNC]]
; CHECK: [[C8:%[0-9]+]]:_(s32) = G_CONSTANT i32 8
; CHECK: [[C9:%[0-9]+]]:_(s32) = G_CONSTANT i32 65535
; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY [[C8]](s32)
; CHECK: [[AND1:%[0-9]+]]:_(s32) = G_AND [[COPY]], [[C9]]
; CHECK: [[C10:%[0-9]+]]:_(s32) = G_CONSTANT i32 255
; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[C1]](s32)
; CHECK: [[AND2:%[0-9]+]]:_(s32) = G_AND [[COPY1]], [[C10]]
; CHECK: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[AND2]], [[AND1]](s32)
; CHECK: [[TRUNC2:%[0-9]+]]:_(s16) = G_TRUNC [[SHL]](s32)
; CHECK: [[OR:%[0-9]+]]:_(s16) = G_OR [[AND]], [[TRUNC2]]
; CHECK: [[TRUNC3:%[0-9]+]]:_(s16) = G_TRUNC [[C2]](s32)
; CHECK: [[AND3:%[0-9]+]]:_(s16) = G_AND [[TRUNC3]], [[TRUNC]]
; CHECK: [[C11:%[0-9]+]]:_(s32) = G_CONSTANT i32 8
; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY [[C11]](s32)
; CHECK: [[AND4:%[0-9]+]]:_(s32) = G_AND [[COPY2]], [[C9]]
; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY [[C3]](s32)
; CHECK: [[AND5:%[0-9]+]]:_(s32) = G_AND [[COPY3]], [[C10]]
; CHECK: [[SHL1:%[0-9]+]]:_(s32) = G_SHL [[AND5]], [[AND4]](s32)
; CHECK: [[TRUNC4:%[0-9]+]]:_(s16) = G_TRUNC [[SHL1]](s32)
; CHECK: [[OR1:%[0-9]+]]:_(s16) = G_OR [[AND3]], [[TRUNC4]]
; CHECK: [[TRUNC5:%[0-9]+]]:_(s16) = G_TRUNC [[C4]](s32)
; CHECK: [[AND6:%[0-9]+]]:_(s16) = G_AND [[TRUNC5]], [[TRUNC]]
; CHECK: [[C12:%[0-9]+]]:_(s32) = G_CONSTANT i32 8
; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY [[C12]](s32)
; CHECK: [[AND7:%[0-9]+]]:_(s32) = G_AND [[COPY4]], [[C9]]
; CHECK: [[COPY5:%[0-9]+]]:_(s32) = COPY [[C5]](s32)
; CHECK: [[AND8:%[0-9]+]]:_(s32) = G_AND [[COPY5]], [[C10]]
; CHECK: [[SHL2:%[0-9]+]]:_(s32) = G_SHL [[AND8]], [[AND7]](s32)
; CHECK: [[TRUNC6:%[0-9]+]]:_(s16) = G_TRUNC [[SHL2]](s32)
; CHECK: [[OR2:%[0-9]+]]:_(s16) = G_OR [[AND6]], [[TRUNC6]]
; CHECK: [[TRUNC7:%[0-9]+]]:_(s16) = G_TRUNC [[C6]](s32)
; CHECK: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[OR]](s16), [[OR1]](s16), [[OR2]](s16), [[TRUNC7]](s16)
; CHECK: [[TRUNC8:%[0-9]+]]:_(s56) = G_TRUNC [[MV]](s64)
; CHECK: S_NOP 0, implicit [[TRUNC8]](s56)
%0:_(s8) = G_CONSTANT i8 0
%1:_(s8) = G_CONSTANT i8 1
%2:_(s8) = G_CONSTANT i8 2
%3:_(s8) = G_CONSTANT i8 3
%4:_(s8) = G_CONSTANT i8 4
%5:_(s8) = G_CONSTANT i8 5
%6:_(s8) = G_CONSTANT i8 6
%7:_(s56) = G_MERGE_VALUES %0, %1, %2, %3, %4, %5, %6
S_NOP 0, implicit %7
...

View File

@ -9,6 +9,10 @@
#include "GISelMITest.h"
using namespace LegalizeActions;
using namespace LegalizeMutations;
using namespace LegalityPredicates;
namespace {
class DummyGISelObserver : public GISelChangeObserver {
@ -900,4 +904,34 @@ TEST_F(GISelMITest, WidenScalarBuildVector) {
EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF;
}
TEST_F(GISelMITest, LowerMergeValues) {
if (!TM)
return;
const LLT S24 = LLT::scalar(24);
const LLT S9 = LLT::scalar(9);
const LLT S3 = LLT::scalar(3);
DefineLegalizerInfo(A, {
getActionDefinitionsBuilder(G_UNMERGE_VALUES)
.widenScalarIf(typeIs(1, LLT::scalar(3)), changeTo(1, LLT::scalar(9)));
});
AInfo Info(MF->getSubtarget());
DummyGISelObserver Observer;
LegalizerHelper Helper(*MF, Info, Observer, B);
B.setInsertPt(*EntryMBB, EntryMBB->end());
// 24 = 3 3 3 3 3 3 3 3
// => 9
//
// This can do 2 merges for the first parts, but has 2 leftover operands.
SmallVector<Register, 7> MergeOps;
for (int I = 0; I != 8; ++I)
MergeOps.push_back(B.buildConstant(S3, I).getReg(0));
auto Merge = B.buildMerge(S24, MergeOps);
EXPECT_EQ(LegalizerHelper::LegalizeResult::UnableToLegalize,
Helper.lower(*Merge, 1, S9));
}
} // namespace