| Issue |
144518
|
| Summary |
[AMDGPU] Avoid or clean unused IMPLICIT_DEF generated from SIFixSGPRCopies pass with REG_SEQUENCE instructions
|
| Labels |
|
| Assignees |
|
| Reporter |
JanekvO
|
An example can be found in `llvm/test/CodeGen/AMDGPU/legalize-amdgcn.raw.ptr.buffer.store.format.f32.ll`:
```
....
[[DEF:%[0-9]+]]:sgpr_32 = IMPLICIT_DEF
[[DEF1:%[0-9]+]]:sgpr_32 = IMPLICIT_DEF
[[REG_SEQUENCE:%[0-9]+]]:vreg_64 = REG_SEQUENCE [[COPY4]], %subreg.sub0, [[COPY3]], %subreg.sub1
....
```
Where the implicit_defs remain unused
Seems to be caused by some juggling of sgpr/vgpr with reg_sequence in SIFixSGPRCopies.
```
sgpr = reg_sequence vgpr, ...., vgpr, ....
```
to
```
sgpr = copy vgpr
sgpr = copy vgpr
sgpr = reg_sequence sgpr, ...., sgpr, ....
```
to
```
sgpr = implicit_def
sgpr = implicit_def
vgpr= reg_sequence vgpr, ...., vgpr, ....
<uses changes to vgpr>
```
I assume it's a non-issue, but I'd like to see it not emit implicit_def. Not sure if it's best to avoid the implicit_def altogether or have a clean up stage.
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