[AMDGPU][bisected] LLVM commit breaks shader compilation leading to severe performance issues in blender
System information
- OS: Gentoo Linux
- GPU: Radeon Pro WX 9100
- Kernel version: 5.10.4-gentoo
- Mesa version: Mesa 21.1.0-devel (git-68a785e6)
- Xserver version (if applicable): 1.20.99.1
- Desktop manager and compositor: SwayWM (Wayland)
Describe the issue
When opening Blender (tried versions 2.83, 2.9x, and git master) the following is printed to the terminal:
LLVM triggered Diagnostic Handler: Illegal instruction detected: VOP* instruction violates constant bus restriction
renamable $vgpr2 = V_CNDMASK_B32_e32 32768, killed $vgpr2, implicit killed $vcc, implicit $exec
LLVM failed to compile shader
radeonsi: can't compile a main shader partWhich sees like a quite bad error. However it is not yet clear that you are impeded by this until you add a Grease Pencil object to the scene.
- Open Blender
- Delete the default cube from the scene (press the Delete or X key)
- Add a GP object (shift + a -> Grease Pencil -> Monkey)
- Now as long as the added GP object is select the error message I posted before is spammed to the terminal and the performance is totally unusable. The selection outline is not rendered either.
Regression
I've bisected this down the the llvm commit: 0045786f146e78afee49eee053dc29ebc842fee1 ([AMDGPU] Select s_cselect)
Now I know this is not a Mesa issue specifically, but I didn't find where to file AMDGPU llvm issues. So I hope filing it here is fine.