[Bug tree-optimization/92155] strlen(a) not folded after memset(a, 0, sizeof a)

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92155

--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
Author: msebor
Date: Fri Oct 18 22:26:39 2019
New Revision: 277194

URL: https://gcc.gnu.org/viewcvs?rev=277194&root=gcc&view=rev
Log:
PR tree-optimization/92157 - incorrect strcmp() == 0 result for unknown strings

gcc/testsuite/ChangeLog:

        PR tree-optimization/92157
        * gcc.dg/strlenopt-69.c: Disable test failing due to PR 92155.
        * gcc.dg/strlenopt-87.c: New test.

gcc/ChangeLog:

        PR tree-optimization/92157
        * tree-ssa-strlen.c (handle_builtin_string_cmp): Be prepared for
        compute_string_length to return a negative result.

Added:
    trunk/gcc/testsuite/gcc.dg/strlenopt-87.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/strlenopt-69.c
    trunk/gcc/tree-ssa-strlen.c