[PATCH] D151934: InstCombine: Recognize fneg when performed as bitcasted integer

Thu Aug 31 15:57:20 PDT 2023

arsenm added a comment.

In D151934#4632790 <https://reviews.llvm.org/D151934#4632790>, @goldstein.w.n wrote:

> Depends which context you are talking about. If its with other float instructions sure. If its with integer instructions I'm not so sure.
> Thats why I think it should be `(bitcast (xor (bitcast))` not just `(xor (bitcast))`.
>
> Edit: Although it could go either way, so no real strong opposition.

Canonical form tends to push things into sources, not the other direction. If the integer operation was useful downstream it should have folded before reaching here

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  https://reviews.llvm.org/D151934/new/

https://reviews.llvm.org/D151934