[llvm] [AMDGPU] Add dynamic threshold for DPP atomic optimizer on integer LDS atomics (PR #186762)

[Matt Arsenault via llvm-commits]

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arsenm wrote:

Probably shouldn't be an attribute. Definitely shouldn't have the cl::opt if there's an attribute. If there is an attribute it needs documentation 

https://github.com/llvm/llvm-project/pull/186762