[llvm] [AMDGPU] Defaults for missing dimensions in SYCL required wg size (PR #68872)

[Jakub Chlanda via llvm-commits]

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@@ -317,10 +317,38 @@ static bool processUse(CallInst *CI, bool IsV5OrAbove) {
   return MadeChange;
 }
 
+// SYCL allows required work-group size attribute to be partially specified
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jchlanda wrote:

Agreed, we could use [`MetadataStreamerMsgPackV3::getWorkGroupDimensions`](https://github.com/jchlanda/llvm-project/blob/jakub/amd_rqwgs_sycl/llvm/lib/Target/AMDGPU/AMDGPUHSAMetadataStreamer.cpp#L176) to pad the missing dimensions and keep the metadata intact.

https://github.com/llvm/llvm-project/pull/68872