[Bug middle-end/67662] -fsanitize=undefined cries wolf for X - 1 + X when X is 2**30

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67662

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Wed Sep 23 14:09:48 2015
New Revision: 228051

URL: https://gcc.gnu.org/viewcvs?rev=228051&root=gcc&view=rev
Log:
2015-09-23   Richard Biener  <rguent...@suse.de>

        PR middle-end/67662
        * fold-const.c (fold_binary_loc): Do not reassociate two vars with
        undefined overflow unless they will cancel out.

        * gcc.dg/ubsan/pr67662.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/ubsan/pr67662.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c
    trunk/gcc/testsuite/ChangeLog