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[CodeGen] check artificial subregister before propagate copy (#185751)

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In machine copy propagation pass, do not propagate the subregister copy
if the subreg is artificial
This commit is contained in:
Brox Chen 2026-03-12 11:16:36 -04:00 committed by GitHub
parent 94b55794d1
commit 641ab6ef83
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GPG Key ID: B5690EEEBB952194
2 changed files with 37 additions and 1 deletions
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2
llvm/lib/CodeGen/MachineCopyPropagation.cpp
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@ -819,7 +819,7 @@ void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
assert(SubRegIdx &&
"MI source is not a sub-register of Copy destination");
ForwardedReg = TRI->getSubReg(CopySrcReg, SubRegIdx);
if (!ForwardedReg) {
if (!ForwardedReg || TRI->isArtificial(ForwardedReg)) {
LLVM_DEBUG(dbgs() << "MCP: Copy source does not have sub-register "
<< TRI->getSubRegIndexName(SubRegIdx) << '\n');
continue;

36
llvm/test/CodeGen/AMDGPU/machine-cp-propagation.mir Normal file
View File

@ -0,0 +1,36 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 6
# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx1100 -mattr=+real-true16 -run-pass=machine-cp -o - %s | FileCheck -check-prefixes=CHECK %s
# vgpr2_hi16 should not fold into sgpr4_hi16
---
name: test_machine_copy
alignment: 1
tracksRegLiveness: true
machineFunctionInfo:
isEntryFunction: true
body: |
bb.0:
liveins: $vgpr0, $sgpr4_sgpr5
; CHECK-LABEL: name: test_machine_copy
; CHECK: liveins: $vgpr0, $sgpr4_sgpr5
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: $sgpr0_sgpr1_sgpr2_sgpr3 = S_LOAD_DWORDX4_IMM renamable $sgpr4_sgpr5, 0, 0
; CHECK-NEXT: $vgpr0 = V_AND_B32_e64 1023, killed $vgpr0, implicit $exec
; CHECK-NEXT: $vgpr0 = nuw nsw V_LSHLREV_B32_e64 2, killed $vgpr0, implicit $exec
; CHECK-NEXT: $sgpr4 = S_LOAD_DWORD_IMM killed renamable $sgpr4_sgpr5, 16, 0
; CHECK-NEXT: $vgpr1 = GLOBAL_LOAD_DWORD_SADDR renamable $sgpr2_sgpr3, renamable $vgpr0, 0, 0, implicit $exec
; CHECK-NEXT: $vgpr2 = COPY killed renamable $sgpr4
; CHECK-NEXT: $vgpr1_lo16 = COPY killed renamable $vgpr2_hi16
; CHECK-NEXT: GLOBAL_STORE_DWORD_SADDR killed renamable $vgpr0, killed renamable $vgpr1, killed renamable $sgpr0_sgpr1, 0, 0, implicit $exec
; CHECK-NEXT: S_ENDPGM 0
$sgpr0_sgpr1_sgpr2_sgpr3 = S_LOAD_DWORDX4_IMM renamable $sgpr4_sgpr5, 0, 0
$vgpr0 = V_AND_B32_e64 1023, killed $vgpr0, implicit $exec
$vgpr0 = nuw nsw V_LSHLREV_B32_e64 2, killed $vgpr0, implicit $exec
$sgpr4 = S_LOAD_DWORD_IMM killed renamable $sgpr4_sgpr5, 16, 0
$vgpr1 = GLOBAL_LOAD_DWORD_SADDR renamable $sgpr2_sgpr3, renamable $vgpr0, 0, 0, implicit $exec
$vgpr2 = COPY killed renamable $sgpr4
$vgpr1_lo16 = COPY killed renamable $vgpr2_hi16
GLOBAL_STORE_DWORD_SADDR killed renamable $vgpr0, killed renamable $vgpr1, killed renamable $sgpr0_sgpr1, 0, 0, implicit $exec
S_ENDPGM 0
...