[Bug tree-optimization/100053] tree-fre incorrectly delete a condition

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100053

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 50579
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50579&action=edit
fix for the issue

I am testing this patch - maybe you can test it on the original testcase you
cannot disclose.

Basically the VN iteration logic fails to make sure to re-evaluate predicated
values validity when backwards reachable edges become executable.  Fixing
that would be possible but simply not being optimistic for predicated values
is cheaper, predicated values are a somewhat oddly bolted on feature anyway.