[llvm] [CodeGen] Port AtomicExpand to new Pass Manager (PR #71220)

[via llvm-commits]

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@@ -429,6 +429,7 @@ FUNCTION_PASS("strip-gc-relocates", StripGCRelocates())
 FUNCTION_PASS("structurizecfg", StructurizeCFGPass())
 FUNCTION_PASS("tailcallelim", TailCallElimPass())
 FUNCTION_PASS("typepromotion", TypePromotionPass(TM))
+FUNCTION_PASS("atomicexpand", AtomicExpandPass(TM))
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paperchalice wrote:

Would `expand-atomic` be a better name? We already have `expand-large-div-rem`, `expand-large-fp-convert` and `expand-memcmp`:
https://github.com/llvm/llvm-project/blob/7dd4d28e4196fad83ed78ea342d65e7eaec4a6f1/llvm/lib/Passes/PassRegistry.def#L315-L317

https://github.com/llvm/llvm-project/pull/71220