https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80548
--- Comment #10 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
(In reply to Jeffrey A. Law from comment #9)
> These warnings are certainly sensitive to all kinds of things, so it's
> possible it's just gone latent. The only way to be sure would be to bisect
> all the work between gcc-12 and the trunk and pour over the dumps with a
> fine tooth comb. I would hazard a guess it was Aldy's backwards threader
> work, particularly around not bailing out too early for subpaths based on
> comments in the BZ, but one would have to bisect to be 100% sure.
The commit that made the warning disappear is actually the one fixing PR106754.
commit 0a4a2667dc115ca73b552fcabf8570620dfbe55f
Author: Richard Biener <rguent...@suse.de>
Date: 2022-09-06 13:46:00 +0200
tree-optimization/106754 - fix compute_control_dep_chain defect
The following handles the situation of a loop exit along the
control path to the PHI def or from there to the use in a different
way, aoviding premature abort of the walks as noticed in the two
cases where the exit is outermost (gcc.dg/uninit-pred-11.c) or
wrapped in a condition that is on the path (gcc.dg/uninit-pred-12.c).
Instead of handling such exits during recursion we now pick them
up in the parent when walking post-dominators. That requires an
additional post-dominator walk at the outermost level which is
facilitated by splitting out the walk to a helper function and
the existing wrapper added earlier.
The patch also removes the bogus early exit from
uninit_analysis::init_use_preds, fixing a simplified version
of the PR106155 testcase.
