[llvm] [AMDGPU] Enable constant offset promotion to immediate FLAT (PR #93884)

[Matt Arsenault via llvm-commits]

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@@ -2055,10 +2055,16 @@ bool SILoadStoreOptimizer::promoteConstantOffsetToImm(
   if (!(MI.mayLoad() ^ MI.mayStore()))
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arsenm wrote:

Atomics have identical addressing modes, they should be handled the same way 

https://github.com/llvm/llvm-project/pull/93884