[llvm] [AMDGPU] Skip register uses in AMDGPUResourceUsageAnalysis (PR #133242)

[Sebastian Neubauer via llvm-commits]

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@@ -4255,10 +4255,9 @@ same *vendor-name*.
                                                                   wavefront for
                                                                   GFX6-GFX9. A register
                                                                   is required if it is
-                                                                  used explicitly, or
+                                                                  written to, or
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Flakebi wrote:

nit: reading from a register should count as well (e.g. a function that reads arguments from high VGPRs, or a shader that reads hw-initialized registers and only writes to lower VGPRs).

https://github.com/llvm/llvm-project/pull/133242