[Bug tree-optimization/63989] tree-ssa-strlen.c doesn't handle constant pointer plus and array refs if constant offset is smaller than known constant string length

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63989

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Jan  8 21:30:56 2015
New Revision: 219362

URL: https://gcc.gnu.org/viewcvs?rev=219362&root=gcc&view=rev
Log:
    PR tree-optimization/63989
    * params.def (PARAM_MAX_TRACKED_STRLENS): Increment default
    from 1000 to 10000.
    * tree-ssa-strlen.c (get_strinfo): Moved earlier.
    (get_stridx): If we don't have a record for certain SSA_NAME,
    but it is POINTER_PLUS_EXPR of some SSA_NAME we do with
    constant offset, call get_stridx_plus_constant.
    (get_stridx_plus_constant): New function.
    (zero_length_string): Don't use get_stridx here.

    * gcc.dg/strlenopt-27.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/strlenopt-27.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/params.def
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-strlen.c