[clang] [llvm] [HLSL] Adding Flatten and Branch if attributes (PR #116331)

[via llvm-commits]

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@@ -53,3 +53,6 @@ LLVM_FIXED_MD_KIND(MD_DIAssignID, "DIAssignID", 38)
 LLVM_FIXED_MD_KIND(MD_coro_outside_frame, "coro.outside.frame", 39)
 LLVM_FIXED_MD_KIND(MD_mmra, "mmra", 40)
 LLVM_FIXED_MD_KIND(MD_noalias_addrspace, "noalias.addrspace", 41)
+// TODO: this will likelly be placed somewhere else,
+// so we don't mix dxil/hlsl/spirv and clang metadata
+LLVM_FIXED_MD_KIND(MD_dxil_controlflow_hints, "dx.controlflow.hints", 42)
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joaosaffran wrote:

@nikic @llvm-beanz removed the changes in IR Builder. Since this metadata is just passing through the backend, I am using `hlsl.controlflow.hint` and `dx.controlflow.hints`, the latter to keep compatibility with DXIL. 

https://github.com/llvm/llvm-project/pull/116331