[clang] [llvm] [HLSL] implement elementwise firstbithigh hlsl builtin (PR #111082)

[Farzon Lotfi via cfe-commits]

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+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-unknown %s -o - -filetype=obj | spirv-val %}
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farzonl wrote:

Do you have spirv-tools installed?

There is an error in DXCs SPIRV backend
`error: firstbithigh is currently limited to 32-bit width components when targetting SPIR-V`

That makes me think there might be a problem with non 32 bit width values that you use in this test. short of running the shader I don't know how to confirm. Maybe someone with more knowledge could weigh in. 

https://github.com/llvm/llvm-project/pull/111082