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andyleiserson opened this issue Apr 14, 2025 · 2 comments · May be fixed by #7554
Open

"Instructions after return" is reported incorrectly #7536

andyleiserson opened this issue Apr 14, 2025 · 2 comments · May be fixed by #7554
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@andyleiserson
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area: correctness We're behaving incorrectly area: naga processing Passes over IR in the middle lang: WGSL WebGPU Shading Language type: bug Something isn't working

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@andyleiserson
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This failure appears in https://shi-yan.github.io/webgpuunleashed/code/code.html#5_04_mega_texture, via https://bugzilla.mozilla.org/show_bug.cgi?id=1911496.

The shader fails with:

Shader validation error: Entry point fs_main at Fragment is invalid
   ┌─ :54:12
   │
54 │     return vec4(1.0,0.0,0.0,1.0);
   │            ^^^^^^^^^^^^^^^^^^^^^ instructions after return
   │
   = There are instructions after `return`/`break`/`continue`
@andyleiserson andyleiserson added type: bug Something isn't working area: correctness We're behaving incorrectly lang: WGSL WebGPU Shading Language area: naga processing Passes over IR in the middle labels Apr 14, 2025
@andyleiserson
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This shader has a discard followed by the return shown in the error message. I think the real issue here is that we treat There are instructions after `return`/`break`/`continue` as an error. Unreachable code may be poor style, but it's allowed by the spec.

@cwfitzgerald
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It used to be disallowed, which is where the rule came from

@andyleiserson andyleiserson self-assigned this Apr 15, 2025
andyleiserson added a commit to andyleiserson/wgpu that referenced this issue Apr 16, 2025
@andyleiserson
[naga] Warn, rather than error, on unreachable statements
bbc1389 
Fixes gfx-rs#7536
@andyleiserson andyleiserson linked a pull request Apr 16, 2025 that will close this issue
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@andyleiserson andyleiserson moved this from Todo to In Progress in WebGPU for Firefox Apr 16, 2025
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@andyleiserson andyleiserson

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area: correctness We're behaving incorrectly area: naga processing Passes over IR in the middle lang: WGSL WebGPU Shading Language type: bug Something isn't working
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WebGPU for Firefox
Status: In Progress
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[naga] Warn, rather than error, on unreachable statements andyleiserson/wgpu
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@cwfitzgerald @andyleiserson