[llvm] [AMDGPU] Fix handling of setting register classes in MFMA scheduler rewrite stage (PR #181047)

[Tony Linthicum via llvm-commits]

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+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx942 -O1 -amdgpu-disable-rewrite-mfma-form-sched-stage=false -verify-machineinstrs < %s
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tlinthic wrote:

Will do.

https://github.com/llvm/llvm-project/pull/181047