[llvm] [AMDGPU] Set SGPR spill stack IDs when creating spill slots (PR #197628)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,62 @@
+; RUN: llc -O1 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx90a -verify-machineinstrs -o - %s > /dev/null
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arsenm wrote:

```suggestion
; RUN: llc -O1 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx90a < %s | FileCheck %s
```

Should generate checks. Also drop -O1 if possible 

https://github.com/llvm/llvm-project/pull/197628