[llvm] [AMDGPU] Improve StructurizeCFG pass performance by using SSAUpdaterBulk. (PR #130611)

[via llvm-commits]

github-actions[bot] wrote:

<!--LLVM CODE FORMAT COMMENT: {undef deprecator}-->


:warning: undef deprecator found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

``````````bash
git diff -U0 --pickaxe-regex -S '([^a-zA-Z0-9#_-]undef[^a-zA-Z0-9_-]|UndefValue::get)' e0442bdfa5a5cd02431955cb18b67194d2b82faf 05da60e8fd685b3076edd6b318e61c19047ed056 llvm/lib/Transforms/Scalar/StructurizeCFG.cpp llvm/test/CodeGen/AMDGPU/branch-folding-implicit-def-subreg.ll llvm/test/CodeGen/AMDGPU/memcpy-crash-issue63986.ll llvm/test/CodeGen/AMDGPU/nested-loop-conditions.ll llvm/test/CodeGen/AMDGPU/si-unify-exit-multiple-unreachables.ll llvm/test/CodeGen/AMDGPU/unstructured-cfg-def-use-issue.ll llvm/test/Transforms/StructurizeCFG/AMDGPU/loop-subregion-misordered.ll llvm/test/Transforms/StructurizeCFG/bug36015.ll llvm/test/Transforms/StructurizeCFG/interleaved-loop-order.ll llvm/test/Transforms/StructurizeCFG/nested-loop-order.ll llvm/test/Transforms/StructurizeCFG/nested-loop-subregion.ll llvm/test/Transforms/StructurizeCFG/workarounds/needs-fix-reducible.ll
``````````

</details>


The following files introduce new uses of undef:
 - llvm/test/Transforms/StructurizeCFG/bug36015.ll
 - llvm/test/Transforms/StructurizeCFG/nested-loop-order.ll

[Undef](https://llvm.org/docs/LangRef.html#undefined-values) is now deprecated and should only be used in the rare cases where no replacement is possible. For example, a load of uninitialized memory yields `undef`. You should use `poison` values for placeholders instead.

In tests, avoid using `undef` and having tests that trigger undefined behavior. If you need an operand with some unimportant value, you can add a new argument to the function and use that instead.

For example, this is considered a bad practice:
```llvm
define void @fn() {
  ...
  br i1 undef, ...
}
```

Please use the following instead:
```llvm
define void @fn(i1 %cond) {
  ...
  br i1 %cond, ...
}
```

Please refer to the [Undefined Behavior Manual](https://llvm.org/docs/UndefinedBehavior.html) for more information.



https://github.com/llvm/llvm-project/pull/130611