[llvm] AMDGPU: Drop and upgrade llvm.amdgcn.atomic.csub/cond.sub to atomicrmw (PR #105553)

[Matt Arsenault via llvm-commits]

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@@ -271,6 +271,8 @@ def : GINodeEquiv<G_AMDGPU_TBUFFER_STORE_FORMAT_D16, SItbuffer_store_d16>;
 // FIXME: Check MMO is atomic
 def : GINodeEquiv<G_ATOMICRMW_UINC_WRAP, atomic_load_uinc_wrap_glue>;
 def : GINodeEquiv<G_ATOMICRMW_UDEC_WRAP, atomic_load_udec_wrap_glue>;
+def : GINodeEquiv<G_ATOMICRMW_USUB_COND, atomic_load_usub_cond_glue>;
+def : GINodeEquiv<G_ATOMICRMW_USUB_SAT, atomic_load_usub_sat_glue>;
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arsenm wrote:

Most of these backend changes belong in #141068 

https://github.com/llvm/llvm-project/pull/105553