tree fde6bef5a8f3ee8b0702d8037d03cf76e36e95f4
parent 4ae315b0d11882f341c22147672e1661bcb3b7d7
author David Turner <david.turner.dev@gmail.com> 1583405225 +0000
committer Commit Bot service account <commit-bot@chromium.org> 1583405225 +0000

Vulkan: Enforce fixed subgroup size for compute shaders.

This CL ensures that, on architectures with a varying subgroup size,
compute shaders are always compiled with a fixed subgroup size to
avoid consistency issues when one shader writes data in a subgroup-size
dependent layout to GPU memory, to be read by another shader in a
future dispatch.

At the moment, only Intel ICDs are known to implement this [1],
and the code uses a heuristics to chose the size of 16, which seems to
be the sweet spot according to Intel engineers.

+ Update the PNextChainBuilder class to deal with the fact that
  VkComputePipelineCreateInfo::pNext is defined as a const void*,
  which created compiler errors in the previous implementation.

[1] https://bugs.freedesktop.org/show_bug.cgi?id=108875

Change-Id: I332faa53b9f854a8abe43a7271f30d8c5deb2142
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/16021
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>