[llvm] [AMDGPU] Add baseline tests for RewriteMFMAFormSchedStage (PR #193429)

[via llvm-commits]

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@@ -0,0 +1,400 @@
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx950 \
+; RUN:     -amdgpu-disable-rewrite-mfma-form-sched-stage=false \
+; RUN:     < %s | FileCheck %s
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx950 \
+; RUN:     -amdgpu-disable-rewrite-mfma-form-sched-stage=false \
+; RUN:     -stop-before=machine-scheduler \
+; RUN:     < %s | FileCheck %s --check-prefix=BEFORE
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xgxanq wrote:

> Same as the other one, don't see the point of the extra runs

There's really no great need for stop-before. But the first run CHECK is actually used for comparison with the Fix PR 
version.https://github.com/llvm/llvm-project/pull/194887. Because the fix version results in fewer v_accvgpr_read_b32 instructions.

https://github.com/llvm/llvm-project/pull/193429