[Bug tree-optimization/90989] incorrrect strlen result after second strcpy into the same destination

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90989

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
      Known to work|                            |8.3.0
           Keywords|                            |wrong-code
   Last reconfirmed|                            |2019-06-24
           Assignee|unassigned at gcc dot gnu.org      |msebor at gcc dot gnu.org
             Blocks|                            |83819
     Ever confirmed|0                           |1
      Known to fail|                            |10.0, 9.1.0

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The bug was introduced by my r263018:   

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.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83819
[Bug 83819] [meta-bug] missing strlen optimizations