[Bug tree-optimization/86043] strlen after memcpy partially overwriting a string not optimized

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86043

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
Author: msebor
Date: Thu Jul 26 16:45:43 2018
New Revision: 263018

URL: https://gcc.gnu.org/viewcvs?rev=263018&root=gcc&view=rev
Log:
PR tree-optimization/86043 - strlen after memcpy partially overwriting a string
not optimized
PR tree-optimization/86042 - missing strlen optimization after second strcpy

gcc/ChangeLog:

        PR tree-optimization/86043
        PR tree-optimization/86042
        * tree-ssa-strlen.c (handle_builtin_memcpy): Handle strict overlaps.
        (get_string_cst_length): Rename...
        (get_min_string_length): ...to this.  Add argument.
        (handle_char_store): Extend to handle multi-character stores by
        MEM_REF.
        * tree.c (initializer_zerop): Use new argument.  Handle MEM_REF.
        * tree.h (initializer_zerop): Add argument.

gcc/testsuite/ChangeLog:

        PR tree-optimization/86043
        PR tree-optimization/86042
        * gcc/testsuite/gcc.dg/attr-nonstring-2.c: Xfail test cases due to
        pr86688.
        * gcc.dg/strlenopt-44.c: New test.


Added:
    trunk/gcc/testsuite/gcc.dg/strlenopt-54.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/attr-nonstring-2.c
    trunk/gcc/tree-ssa-strlen.c
    trunk/gcc/tree.c
    trunk/gcc/tree.h