[llvm] [AMDGPU] Add function attribute to disable TBUFFER combine (PR #156454)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> > This is not a robust feature design, it is hacking out a singular transformation. You need to define a semantic meaning, have the default be conservatively correct
> 
> Hi, Matt, I don't know how to define a semantic meaning, could you please give me some suggestions?

Is this the same as relaxed-buffer-oob-mod?

https://github.com/llvm/llvm-project/pull/156454