| Issue |
164779
|
| Summary |
[AMDGPU] CodeGen regressions after #154336
|
| Labels |
backend:AMDGPU
|
| Assignees |
|
| Reporter |
jayfoad
|
#154336 causes performance regressions in a few of our graphics benchmarks. From staring at some large before-and-after shader dumps it seems that the slower shaders simply have more computational instructions in them (v_mul_f32, v_fme_f32 and similar). I tried automatically reducing a test case and came up with: [r.txt](https://github.com/user-attachments/files/23094138/r.txt)
```
$ opt -S -p=instcombine,scalarizer,instcombine < r.txt
```
Before #154336, all the math is removed and the function just returns `poison`. After #154336, none of the math is removed.
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