[llvm] [InstSimplify] Guard and/or implied-cond folds against poison (PR #211534)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> %a is false and %b is poison (samesign is violated), so the and is a well-defined false.

`and` propagates poison. So the result is poison.

We call it `bitwise and`. The `logical and` is `select i1 %x, i1 %y, i1 false` which doesn't propagate poison. 

I tried all cases from your tests in Alive2 https://alive2.llvm.org/ce/z/UgjRxy https://alive2.llvm.org/ce/z/W23jLr
All the transformations are correct.

Can you please provide an Alive2 link to demonstrate the miscompilation?


https://github.com/llvm/llvm-project/pull/211534