[llvm] [SLP] Make getSameOpcode support interchangeable instructions. (PR #132887)

[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)' 07c82b1622de1c5c4329ffb769bef7fef1b07429 58f09d66f8b22bf52994c8f3e125f99506c96fe8 llvm/test/Transforms/SLPVectorizer/X86/BinOpSameOpcodeHelper.ll llvm/test/Transforms/SLPVectorizer/isOpcodeOrAlt.ll llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp llvm/test/Transforms/SLPVectorizer/AArch64/vec3-base.ll llvm/test/Transforms/SLPVectorizer/RISCV/reversed-strided-node-with-external-ptr.ll llvm/test/Transforms/SLPVectorizer/RISCV/vec3-base.ll llvm/test/Transforms/SLPVectorizer/X86/barriercall.ll llvm/test/Transforms/SLPVectorizer/X86/bottom-to-top-reorder.ll llvm/test/Transforms/SLPVectorizer/X86/buildvector-postpone-for-dependency.ll llvm/test/Transforms/SLPVectorizer/X86/bv-shuffle-mask.ll llvm/test/Transforms/SLPVectorizer/X86/extract-scalar-from-undef.ll llvm/test/Transforms/SLPVectorizer/X86/extractcost.ll llvm/test/Transforms/SLPVectorizer/X86/gathered-delayed-nodes-with-reused-user.ll llvm/test/Transforms/SLPVectorizer/X86/minbitwidth-drop-wrapping-flags.ll llvm/test/Transforms/SLPVectorizer/X86/multi-extracts-bv-combined.ll llvm/test/Transforms/SLPVectorizer/X86/non-scheduled-inst-reused-as-last-inst.ll llvm/test/Transforms/SLPVectorizer/X86/propagate_ir_flags.ll llvm/test/Transforms/SLPVectorizer/X86/reduced-val-vectorized-in-transform.ll llvm/test/Transforms/SLPVectorizer/X86/reorder_diamond_match.ll llvm/test/Transforms/SLPVectorizer/X86/shuffle-mask-emission.ll llvm/test/Transforms/SLPVectorizer/X86/vec3-base.ll llvm/test/Transforms/SLPVectorizer/X86/vect_copyable_in_binops.ll llvm/test/Transforms/SLPVectorizer/alternate-opcode-sindle-bv.ll llvm/test/Transforms/SLPVectorizer/resized-alt-shuffle-after-minbw.ll llvm/test/Transforms/SLPVectorizer/shuffle-mask-resized.ll
``````````

</details>


The following files introduce new uses of undef:
 - llvm/test/Transforms/SLPVectorizer/X86/extract-scalar-from-undef.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/132887