Vulkan examples regression: descriptor indexing and oit

[SRSaunders]

I have been working on updating macOS and iOS support and fixing a few defects that I found in Sascha Willems' Vulkan examples repository. See SaschaWillems/Vulkan#1117 and SaschaWillems/Vulkan#1119. During this work I observed two examples that expose what appear to regressions across MoltenVK releases:

• The descriptorindexing example runs well on Vulkan SDK 1.3.250.1/MoltenVK 1.2.4, but fails on any later release with:

[mvk-error] SPIR-V to MSL conversion error: Argument buffer resource base type could not be determined. When padding argument buffer elements, all descriptor set resources must be supplied with a base type by the app.
[mvk-error] VK_ERROR_INVALID_SHADER_NV: Fragment shader function could not be compiled into pipeline. See previous logged error.
Fatal : VkResult is "ERROR_INVALID_SHADER_NV" in /Users/steve/XcodeProjects/Vulkan/examples/descriptorindexing/descriptorindexing.cpp at line 346
Assertion failed: (res == VK_SUCCESS), function preparePipelines, file descriptorindexing.cpp, line 346.

• The oit example runs well up to SDK 1.3.275.0/MoltenVK 1.2.7, but fails on the current release (1.3.280.0/1):

-[MTLTextureDescriptorInternal validateWithDevice:]:1344: failed assertion `Texture Descriptor Validation
MTLTextureUsage has unknown bits 0x20.

The first of these may be a duplicate of #2180, but I just wanted to report them here to make sure the MoltenVK team is aware.

[SRSaunders]

After a bit of debugging, I believe the first one is a SPIRVCross defect. I patched in the old SPIRVCross (from MoltenVK 1.2.4) at commit 12542fc to the most recent head of MoltenVK 1.2.9. I had to comment out a few newer msl options, but this did not seem to affect things for the descriptorindexing example. I now have a working example with this mashup. Note the newest SPRIVCross for SDK 1.3.283/MVK 1.2.9 does not fix it.

I have not done any research on the second issue above (oit example). Using the older SPIRVCross does not fix it.

[SRSaunders]

Issue one (descriptorindexing) reported with additional data at the existing KhronosGroup/SPIRV-Cross#2198

Issue two (oit) still not understood.

[cdavis5e]

The oit example runs well up to SDK 1.3.275.0/MoltenVK 1.2.7, but fails on the current release (1.3.280.0/1):

-[MTLTextureDescriptorInternal validateWithDevice:]:1344: failed assertion `Texture Descriptor Validation
MTLTextureUsage has unknown bits 0x20.

What OS? More specifically, what version?

[SRSaunders]

OS is Ventura 13.6.6 (on x86) with Xcode 15.2. GPU is AMD Radeon 6600 (Metal Tier 2).

[cdavis5e]

OS is Ventura 13.6.6 (on x86) with Xcode 15.2. GPU is AMD Radeon 6600 (Metal Tier 2).

The bit 0x20 is MTLTextureUsageShaderAtomic, which wasn't introduced until Sonoma. We shouldn't be using that bit prior to Sonoma.

[billhollings]

The descriptorindexing example runs well on Vulkan SDK 1.3.250.1/MoltenVK 1.2.4, but fails on any later release... /clip/ ...The first of these may be a duplicate of #2180, but I just wanted to report them here to make sure the MoltenVK team is aware.

Thanks for submitting this as an issue affecting a known sample app! It made it much easier to track down!

PR #2231 fixes this part of this issue.

[billhollings]

OS is Ventura 13.6.6 (on x86) with Xcode 15.2. GPU is AMD Radeon 6600 (Metal Tier 2).

The bit 0x20 is MTLTextureUsageShaderAtomic, which wasn't introduced until Sonoma. We shouldn't be using that bit prior to Sonoma.

@SRSaunders Can you try changing:

MoltenVK/MoltenVK/MoltenVK/GPUObjects/MVKImage.mm

Line 1084 in 1abae61

MTLTextureUsage mtlUsage = pixFmts->getMTLTextureUsage(getCombinedUsage(), mtlPixFmt, _samples, _isLinear || _isLinearForAtomics, needsReinterpretation, _hasExtendedUsage, _shouldSupportAtomics);

to include , _shouldSupportAtomics && getPhysicalDevice()->useNativeTextureAtomics()); (and maybe put a couple of line-returns as needed to make the line not so far off to the right), and then retest, please?

[SRSaunders]

Fantastic! Both issues are solved for me now.

For issue one (arg buffer padding), I checked out KhronosGroup/SPIRV-Cross@e41d79f and rebuilt the External Dependencies project, followed by the MoltenVK project. The descriptorindexing example is now working fine.

For issue two (MTLTextureUsageShaderAtomic), I added your additional code and rebuilt MoltenVK. The oit example is now working again.

Thanks for jumping on these and solving so quickly.

[billhollings]

For issue two (MTLTextureUsageShaderAtomic), I added your additional code and rebuilt MoltenVK. The oit example is now working again.

Wonderful! Thanks for testing.

I'll make that simple change here and run CTS to see if it breaks anything, then I'll issue a PR.

[billhollings]

For issue two (MTLTextureUsageShaderAtomic), I added your additional code and rebuilt MoltenVK. The oit example is now working again.

Wonderful! Thanks for testing.

I'll make that simple change here and run CTS to see if it breaks anything, then I'll issue a PR.

The updated PR #2231 now also fixes this part of this issue.

[SRSaunders]

I have now tested against the new merged PR and the Vulkan examples work well. Thanks again.

Closing issue.