Texture compression unaligned

[castano]

Issue: gpuweb/gpuweb#2006

Add tests to support the proposed 'texture-compression-unaligned' feature. gpuweb/gpuweb#6312

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Requirements for PR author:

• All missing test coverage is tracked with "TODO" or .unimplemented().
• New helpers are /** documented */ and new helper files are found in helper_index.txt.
• Test behaves as expected in a WebGPU implementation. (If not passing, explain above.)
• Test have be tested with compatibility mode validation enabled and behave as expected. (If not passing, explain above.)

Requirements for reviewer sign-off:

• Tests are properly located.
• Test descriptions are accurate and complete.
• Tests provide complete coverage (including validation control cases). Missing coverage MUST be covered by TODOs.
• Tests avoid over-parameterization (see case count report).

When landing this PR, be sure to make any necessary issue status updates.

[github-actions]

Results for build job (at 359fd6c):

-webgpu:api,operation,adapter,requestDevice:features,known:* - 24 cases, 24 subcases (~1/case)
+webgpu:api,operation,adapter,requestDevice:features,known:* - 25 cases, 25 subcases (~1/case)
+webgpu:api,operation,command_buffer,copyTextureToTexture:color_textures,compressed,unaligned,non_array:* - 94 cases, 1974 subcases (~21/case)
+webgpu:api,operation,command_buffer,image_copy:compressed_textures,unaligned_mip_level_0:* - 156 cases, 780 subcases (~5/case)
+webgpu:api,validation,capability_checks,features,texture_compression_unaligned:createTexture,unaligned_size:* - 416 cases, 416 subcases (~1/case)
-TOTAL: 283187 cases, 2326095 subcases
+TOTAL: 283854 cases, 2329266 subcases

[Kangz]

I added experimental support for the extension in Chromium that you can try with --enable-unsafe-webgpu. It should appear in a Chromium Canary today or tomorrow (see when releases are listed here)

[castano]

I added experimental support for the extension in Chromium that you can try with --enable-unsafe-webgpu. It should appear in a Chromium Canary today or tomorrow (see when releases are listed here)

Thanks @Kangz! I tried with --enable-unsafe-webgpu on Chrome Canary 152.0.7939.2 and still don't see the feature exposed. Is this only exposed in Chromium? Are there any other flags that I may be missing?

[Kangz]

My bad, I thought the Chromium change trivial so I didn't check and I missed something. With that CL I can see the feature exposed locally (on mac M1) with --enable-unsafe-webgpu. So on Monday it should be in Canary.

[Kangz]

And I can't land that last CL because the existing tests will enable texture-compression-unaligned and fail. We should land this PR and follow up with completing tests afterwards. I checked earlier that the test pass with dawn.node. @kainino0x PTAL!

[Kangz]

Looking at the coverage, I think we should have at least one more test that samples a texture with unaligned mip level 0 and checks that the correct texel value is returned for the border (so the value in the middle of the block and not the border of the block itself).

I'll land the Chromium CL and try to get agreement in the WebGPU WG to land the feature in the spec after testing is done.

[Kangz]

https://chromium-review.git.corp.google.com/c/chromium/src/+/8064574 landed in Chromium so it should soon be possible to test texture-compression-unaligned in Canary. I'm also giving a try at adding it to the GL backend.