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AMDGPU: Don't delete instructions if S_ENDPGM has implicit uses 

This can leave behind the uses with the defs removed.
Since this should only really happen in tests, it's not worth the
effort of trying to handle this.

llvm-svn: 340866
This commit is contained in:
Matt Arsenault 2018-08-28 18:55:55 +00:00
parent 6b4d343e13
commit 755f41f3a2
2 changed files with 25 additions and 1 deletions
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9
llvm/lib/Target/AMDGPU/SIOptimizeExecMaskingPreRA.cpp
View File

@ -119,7 +119,14 @@ bool SIOptimizeExecMaskingPreRA::runOnMachineFunction(MachineFunction &MF) {
// Try to remove unneeded instructions before s_endpgm.
if (MBB.succ_empty()) {
if (MBB.empty() || MBB.back().getOpcode() != AMDGPU::S_ENDPGM)
if (MBB.empty())
continue;
// Skip this if the endpgm has any implicit uses, otherwise we would need
// to be careful to update / remove them.
MachineInstr &Term = MBB.back();
if (Term.getOpcode() != AMDGPU::S_ENDPGM ||
Term.getNumOperands() != 0)
continue;
SmallVector<MachineBasicBlock*, 4> Blocks({&MBB});

17
llvm/test/CodeGen/AMDGPU/endpgm-dce.mir
View File

@ -295,3 +295,20 @@ body: |
bb.2:
S_ENDPGM
...
# GCN-LABEL: name: implicit_use_on_s_endpgm
# GCN: V_ADD_I32
# GCN: COPY
# GCN: V_ADDC_U32
# GCN: S_ENDPGM implicit %3
name: implicit_use_on_s_endpgm
tracksRegLiveness: true
body: |
bb.0:
dead %0:vgpr_32 = V_ADD_I32_e32 12345, undef %1:vgpr_32, implicit-def $vcc, implicit $exec
%2:sreg_64_xexec = COPY $vcc
%3:vgpr_32, dead %4:sreg_64_xexec = V_ADDC_U32_e64 undef %5:vgpr_32, undef %6:vgpr_32, %2, implicit $exec
S_ENDPGM implicit %3
...