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wgsl: Propose subgroup-size-control extension#5546

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kainino0x merged 4 commits intogpuweb:mainfrom
Jiawei-Shao:subgroup-size-control
Feb 2, 2026
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wgsl: Propose subgroup-size-control extension#5546
kainino0x merged 4 commits intogpuweb:mainfrom
Jiawei-Shao:subgroup-size-control

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@Jiawei-Shao Jiawei-Shao commented Jan 28, 2026

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github-actions bot commented Jan 28, 2026 •
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Previews, as seen when this build job started (387681f):
WebGPU webgpu.idl | Explainer | Correspondence Reference
WGSL grammar.js | wgsl.lalr.txt

alan-baker
alan-baker reviewed Jan 28, 2026
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jrprice
jrprice reviewed Jan 28, 2026
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jimblandy commented Jan 29, 2026

RESOLVED: accept as proposal

minutes from API/WGSL committee meeting 2026-1-28
  • Rendered:
  • https://github.com/Jiawei-Shao/gpuweb/blob/subgroup-size-control/proposals/subgroup-size-control.md
  • JB: Late addition, committee members haven't had a chance to review. But we have time so let's go over it.
  • JB: PR just adds a proposal, generally lean toward just accepting draft proposal docs. Jiawei can give some introduction/background.
  • JS: Proposal to add a new WGSL attribute to control the subgroup size of WGSL shaders. D3D12 SM6.6 and Vulkan extension. Useful for GPUs that support multiple subgroup sizes. Without this, can only know the subgroup size at runtime inside the shader, so need to have code paths for all possible subgroup sizes on the current hardware. With this attribute we can specialize the shader code for a specific subgroup size. Helps choose workgroup memory size, write optimized shaders, etc.
  • AB: This is a feature we've gotten a lot of requests for. It didn't come with subgroups because it's not implementable on all hardware that have subgroups. It would be interesting to explore whether this can be exposed on Apple - to be able to say it's supported on all three platforms. But we should have it either way. Lot of benefits to be able to specialize your shader.
  • JB: Mike do you know offhand whether this could be implemented on Metal?
  • MW: Don't know offhand.
  • RESOLVED: accept as proposal

@jimblandy jimblandy moved this to Waiting for proposal in WGSL Jan 29, 2026
@jimblandy jimblandy added this to WGSL Jan 29, 2026
Kangz
Kangz approved these changes Feb 2, 2026
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LGTM to land as proposal as the group agreed to.

@kainino0x kainino0x merged commit f76d957 into gpuweb:main Feb 2, 2026
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@github-project-automation github-project-automation bot moved this from Waiting for proposal to Done in WGSL Feb 2, 2026
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@Kangz Kangz Kangz approved these changes

@jrprice jrprice jrprice approved these changes

@alan-baker alan-baker Awaiting requested review from alan-baker

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@Jiawei-Shao @jimblandy @Kangz @jrprice @alan-baker @kainino0x