[Bug middle-end/77357] strlen of constant strings not folded

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77357

--- Comment #6 from Martin Sebor <msebor at gcc dot gnu.org> ---
Author: msebor
Date: Mon Jul  9 20:33:48 2018
New Revision: 262522

URL: https://gcc.gnu.org/viewcvs?rev=262522&root=gcc&view=rev
Log:
PR middle-end/77357 - strlen of constant strings not folded

gcc/ChangeLog:

        PR middle-end/77357
        PR middle-end/86428
        * builtins.c (c_strlen): Avoid out-of-bounds warnings when
        accessing implicitly initialized array elements.
        * expr.c (string_constant): Handle string initializers of
        character arrays within aggregates.
        * gimple-fold.c (fold_array_ctor_reference): Add argument.
        Store element offset.  As a special case, handle zero size.
        (fold_nonarray_ctor_reference): Same.
        (fold_ctor_reference): Add argument.  Store subobject offset.
        * gimple-fold.h (fold_ctor_reference): Add argument.

gcc/testsuite/ChangeLog:

        PR middle-end/77357
        * gcc.dg/strlenopt-49.c: New test.
        * gcc.dg/strlenopt-50.c: New test.
        * gcc.dg/strlenopt-51.c: New test.
        * gcc.dg/strlenopt-52.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/strlenopt-49.c
    trunk/gcc/testsuite/gcc.dg/strlenopt-50.c
    trunk/gcc/testsuite/gcc.dg/strlenopt-51.c
    trunk/gcc/testsuite/gcc.dg/strlenopt-52.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/builtins.c
    trunk/gcc/expr.c
    trunk/gcc/fold-const.c
    trunk/gcc/fold-const.h
    trunk/gcc/gimple-fold.c
    trunk/gcc/gimple-fold.h
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.c-torture/execute/builtins/strlen-3.c