[Bug c/103579] [gcc-10.3.1, gcc-12.0.0] -fno-builtin-memset and -fno-builtin have different effect on optimization

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103579

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WONTFIX
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
That's because of c/c-opt.c:

  /* If -ffreestanding, -fno-hosted or -fno-builtin then disable
     pattern recognition.  */
  if (flag_no_builtin)
    SET_OPTION_IF_UNSET (&global_options, &global_options_set,
                         flag_tree_loop_distribute_patterns, 0);

memset is one of the functions that can always be generated, even without
-fno-builtin[-memset].  Note that -fno-builtin-memset just disables recognizing
'memset', '__builtin_memset' is still available.