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[GlobalISel][AArch64] Use getConstantVRegValWithLookThrough for selectArithImmed 

Instead of just stopping to see if we have a G_CONSTANT, instead, look through
G_TRUNCs, G_SEXTs, and G_ZEXTs.

This gives an average ~1.3% code size improvement on CINT2000 at -O3.

Differential Revision: https://reviews.llvm.org/D64108

llvm-svn: 365063
This commit is contained in:
Jessica Paquette 2019-07-03 17:46:23 +00:00
parent 11953acb13
commit a99cfeea44
3 changed files with 55 additions and 16 deletions
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10
llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
View File

@ -3777,13 +3777,11 @@ static Optional<uint64_t> getImmedFromMO(const MachineOperand &Root) {
else if (Root.isCImm())
Immed = Root.getCImm()->getZExtValue();
else if (Root.isReg()) {
MachineInstr *Def = MRI.getVRegDef(Root.getReg());
if (Def->getOpcode() != TargetOpcode::G_CONSTANT)
auto ValAndVReg =
getConstantVRegValWithLookThrough(Root.getReg(), MRI, true);
if (!ValAndVReg)
return None;
MachineOperand &Op1 = Def->getOperand(1);
if (!Op1.isCImm() || Op1.getCImm()->getBitWidth() > 64)
return None;
Immed = Op1.getCImm()->getZExtValue();
Immed = ValAndVReg->Value;
} else
return None;
return Immed;

44
llvm/test/CodeGen/AArch64/GlobalISel/select-cmp.mir
View File

@ -70,3 +70,47 @@ body: |
RET_ReallyLR implicit $w0
...
---
name: cmp_imm_lookthrough
legalized: true
regBankSelected: true
tracksRegLiveness: true
body: |
bb.1:
liveins: $w0
; CHECK-LABEL: name: cmp_imm_lookthrough
; CHECK: liveins: $w0
; CHECK: [[COPY:%[0-9]+]]:gpr32sp = COPY $w0
; CHECK: $wzr = SUBSWri [[COPY]], 42, 0, implicit-def $nzcv
; CHECK: [[CSINCWr:%[0-9]+]]:gpr32 = CSINCWr $wzr, $wzr, 1, implicit $nzcv
; CHECK: $w0 = COPY [[CSINCWr]]
; CHECK: RET_ReallyLR implicit $w0
%0:gpr(s32) = COPY $w0
%1:gpr(s64) = G_CONSTANT i64 42
%2:gpr(s32) = G_TRUNC %1(s64)
%5:gpr(s32) = G_ICMP intpred(eq), %0(s32), %2
$w0 = COPY %5(s32)
RET_ReallyLR implicit $w0
...
---
name: cmp_imm_lookthrough_bad_trunc
legalized: true
regBankSelected: true
tracksRegLiveness: true
body: |
bb.1:
liveins: $w0
; CHECK-LABEL: name: cmp_imm_lookthrough_bad_trunc
; CHECK: liveins: $w0
; CHECK: [[COPY:%[0-9]+]]:gpr32sp = COPY $w0
; CHECK: $wzr = SUBSWri [[COPY]], 0, 0, implicit-def $nzcv
; CHECK: [[CSINCWr:%[0-9]+]]:gpr32 = CSINCWr $wzr, $wzr, 1, implicit $nzcv
; CHECK: $w0 = COPY [[CSINCWr]]
; CHECK: RET_ReallyLR implicit $w0
%0:gpr(s32) = COPY $w0
%1:gpr(s64) = G_CONSTANT i64 68719476736 ; 0x1000000000
%2:gpr(s32) = G_TRUNC %1(s64) ; Value truncates to 0
%5:gpr(s32) = G_ICMP intpred(eq), %0(s32), %2
$w0 = COPY %5(s32)
RET_ReallyLR implicit $w0

17
llvm/test/CodeGen/AArch64/GlobalISel/select-jump-table-brjt.mir
View File

@ -57,19 +57,16 @@ body: |
; CHECK: successors: %bb.4(0x40000000), %bb.1(0x40000000)
; CHECK: liveins: $w0
; CHECK: [[COPY:%[0-9]+]]:gpr32common = COPY $w0
; CHECK: [[MOVi32imm:%[0-9]+]]:gpr32 = MOVi32imm 71
; CHECK: [[MOVi32imm1:%[0-9]+]]:gpr32 = MOVi32imm 0
; CHECK: [[MOVi32imm:%[0-9]+]]:gpr32 = MOVi32imm 0
; CHECK: [[SUBSWri:%[0-9]+]]:gpr32 = SUBSWri [[COPY]], 4, 0, implicit-def $nzcv
; CHECK: [[SUBREG_TO_REG:%[0-9]+]]:gpr64 = SUBREG_TO_REG 0, [[SUBSWri]], %subreg.sub_32
; CHECK: [[UBFMXri:%[0-9]+]]:gpr64 = UBFMXri [[SUBREG_TO_REG]], 0, 31
; CHECK: [[SUBREG_TO_REG1:%[0-9]+]]:gpr64 = SUBREG_TO_REG 0, [[MOVi32imm]], %subreg.sub_32
; CHECK: [[UBFMXri1:%[0-9]+]]:gpr64 = UBFMXri [[SUBREG_TO_REG1]], 0, 31
; CHECK: $xzr = SUBSXrr [[UBFMXri]], [[UBFMXri1]], implicit-def $nzcv
; CHECK: [[UBFMXri:%[0-9]+]]:gpr64common = UBFMXri [[SUBREG_TO_REG]], 0, 31
; CHECK: $xzr = SUBSXri [[UBFMXri]], 71, 0, implicit-def $nzcv
; CHECK: [[CSINCWr:%[0-9]+]]:gpr32 = CSINCWr $wzr, $wzr, 9, implicit $nzcv
; CHECK: TBNZW [[CSINCWr]], 0, %bb.4
; CHECK: bb.1.entry:
; CHECK: successors: %bb.3(0x2aaaaaab), %bb.4(0x2aaaaaab), %bb.2(0x2aaaaaab)
; CHECK: [[MOVi32imm2:%[0-9]+]]:gpr32 = MOVi32imm 0
; CHECK: [[MOVi32imm1:%[0-9]+]]:gpr32 = MOVi32imm 0
; CHECK: [[MOVaddrJT:%[0-9]+]]:gpr64 = MOVaddrJT target-flags(aarch64-page) %jump-table.0, target-flags(aarch64-pageoff, aarch64-nc) %jump-table.0
; CHECK: early-clobber %18:gpr64, early-clobber %19:gpr64sp = JumpTableDest32 [[MOVaddrJT]], [[UBFMXri]], %jump-table.0
; CHECK: BR %18
@ -79,10 +76,10 @@ body: |
; CHECK: B %bb.4
; CHECK: bb.3.sw.bb1:
; CHECK: successors: %bb.4(0x80000000)
; CHECK: [[MOVi32imm3:%[0-9]+]]:gpr32 = MOVi32imm 3
; CHECK: [[MADDWrrr:%[0-9]+]]:gpr32 = MADDWrrr [[COPY]], [[MOVi32imm3]], $wzr
; CHECK: [[MOVi32imm2:%[0-9]+]]:gpr32 = MOVi32imm 3
; CHECK: [[MADDWrrr:%[0-9]+]]:gpr32 = MADDWrrr [[COPY]], [[MOVi32imm2]], $wzr
; CHECK: bb.4.return:
; CHECK: [[PHI:%[0-9]+]]:gpr32 = PHI [[MADDWrrr]], %bb.3, [[ADDWri]], %bb.2, [[MOVi32imm1]], %bb.0, [[MOVi32imm2]], %bb.1
; CHECK: [[PHI:%[0-9]+]]:gpr32 = PHI [[MADDWrrr]], %bb.3, [[ADDWri]], %bb.2, [[MOVi32imm]], %bb.0, [[MOVi32imm1]], %bb.1
; CHECK: $w0 = COPY [[PHI]]
; CHECK: RET_ReallyLR implicit $w0
bb.1.entry: