[llvm] [polly] [InstSimplify] Fix incorrect poison propagation when folding phi (PR #96631)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> On a somewhat tangential note, I'm also wondering whether it would be worthwhile to add some flags on freeze so you can have freeze %x (freezes undef and poison -- used e.g. for despeculation), freeze undef %x (freezes undef only -- used for multi-use) and freeze poison %x (freezes poison only -- used e.g. for the select fold).

As we will finally get rid of undef, I don't think the (potential) benefit is worth the maintenance burden.


https://github.com/llvm/llvm-project/pull/96631