[llvm] [SPIR-V] Support `nonuniformindex` intrsinsic in SPIRV CodeGen. (PR #162540)

[Steven Perron via llvm-commits]

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s-perron wrote:

You changed this test from a non uniform index into an array of storage images (RWBuffer) into an array of storage buffer (RWStructuredBuffers). Can you look at the full set of tests that we will need? See https://github.com/llvm/llvm-project/pull/122355. 

You cannot generate all of these from HLSL yet. For now add that can be generated from HLSL. Look at the tables in https://github.com/microsoft/DirectXShaderCompiler/blob/main/docs/SPIR-V.rst#textures and https://github.com/microsoft/DirectXShaderCompiler/blob/main/docs/SPIR-V.rst#constanttexturestructuredbyte-buffers to see the links between HLSL type and the Vulkan type.

https://github.com/llvm/llvm-project/pull/162540