[clang] [llvm] Add WaveReadLaneFirst HLSL function (PR #220373)

[Farzon Lotfi via cfe-commits]

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@@ -0,0 +1,98 @@
+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv1.5-vulkan-unknown %s -o - | FileCheck %s
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farzonl wrote:

Are you sure this target triple is correct? I have not seen use use 1.5 in many tests. also I think the unknown here might be messing with the validator. why not target a compute shader?

https://github.com/llvm/llvm-project/pull/220373