[llvm] [AMDGPU] Add DS loop wait optimization infrastructure (1/4) (PR #171942)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,91 @@
+# REQUIRES: asserts
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx1250 -run-pass=si-insert-waitcnts -amdgpu-waitcnt-loop-ds-opt -debug-only=si-insert-waitcnts -filetype-null %s 2>&1 | FileCheck %s
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arsenm wrote:

```suggestion
# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx1250 -run-pass=si-insert-waitcnts -amdgpu-waitcnt-loop-ds-opt -debug-only=si-insert-waitcnts -filetype=null %s 2>&1 | FileCheck %s
```

https://github.com/llvm/llvm-project/pull/171942