[llvm] [Matrix] Add tests identifying GVN and DSE opportunities for matrix store / load intrinsics (PR #163573)

[Florian Hahn via llvm-commits]

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+; RUN: opt < %s -aa-pipeline=basic-aa -passes=aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
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fhahn wrote:

```suggestion
; RUN: opt %s -aa-pipeline=basic-aa -passes=aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
```

https://github.com/llvm/llvm-project/pull/163573