[llvm] 8591640 - [InstCombine] add DeMorgan folds for logical ops in select form

[Florian Hahn via llvm-commits]

> On Jun 14, 2021, at 17:55, Sanjay Patel via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> 
> Author: Sanjay Patel
> Date: 2021-06-14T12:54:35-04:00
> New Revision: 8591640379ac9175a8a8493126ecf0b44e3bb4af
> 
> URL: https://github.com/llvm/llvm-project/commit/8591640379ac9175a8a8493126ecf0b44e3bb4af
> DIFF: https://github.com/llvm/llvm-project/commit/8591640379ac9175a8a8493126ecf0b44e3bb4af.diff
> 
> LOG: [InstCombine] add DeMorgan folds for logical ops in select form
> 
> We canonicalized to these select patterns (poison-safe logic)
> with D101191, so we need to reduce 'not' ops when possible
> as we would with 'and'/'or' instructions.
> 
> This is shown in a secondary example in:
> https://llvm.org/PR50389
> 
> https://alive2.llvm.org/ce/z/BvsESh
> 

It looks like this is causing an infinite loop in InstCombine: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35399 <https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35399>

Cheers,
Florian

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20210620/ba669ebf/attachment.html>