[clang] [llvm] [HLSL][DXIL][SPIRV] QuadReadAcrossX intrinsic support (PR #184360)

[Joshua Batista via cfe-commits]

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@@ -3451,6 +3451,105 @@ __attribute__((convergent)) double3 WavePrefixProduct(double3);
 _HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_prefix_product)
 __attribute__((convergent)) double4 WavePrefixProduct(double4);
 
+//===----------------------------------------------------------------------===//
+// QuadReadAcrossX builtins
+//===----------------------------------------------------------------------===//
+
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.0)
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bob80905 wrote:

Yeah you're right! I'll update the rest in a separate PR, please make that update in your own changes as well. 

https://github.com/llvm/llvm-project/pull/184360