https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68302
--- Comment #4 from Aurelien Jarno <aurelien at aurel32 dot net> ---
The bisection shows that this commit has fixed the issue on trunk:
2015-07-23 Richard Biener <rguent...@suse.de>
PR middle-end/66916
* match.pd: Guard widen and sign-change comparison simplification
with single_use.
That said, it just seems to be a side effect of this commit and not a fix for
the original issue.
