[Bug target/59588] New: Odd codes in ix86_option_override_internal

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59588

            Bug ID: 59588
           Summary: Odd codes in ix86_option_override_internal
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
                CC: ubizjak at gmail dot com

ix86_option_override_internal has

      if (opts->x_ix86_arch_string)
        opts->x_ix86_tune_string = opts->x_ix86_arch_string;
      if (!opts->x_ix86_tune_string)
        {
          opts->x_ix86_tune_string = cpu_names[TARGET_CPU_DEFAULT];
          ix86_tune_defaulted = 1;
        }

      /* opts->x_ix86_tune_string is set to opts->x_ix86_arch_string
         or defaulted.  We need to use a sensible tune option.  */
      if (!strcmp (opts->x_ix86_tune_string, "generic")
          || !strcmp (opts->x_ix86_tune_string, "x86-64")
          || !strcmp (opts->x_ix86_tune_string, "i686"))
        {
          opts->x_ix86_tune_string = "generic";
        }

Why is opts->x_ix86_tune_string changed to "generic".  If
opts->x_ix86_tune_string is "generic". there is no need to
change it to "generic".  If an option is valid for -march=,
it should also be valid for -mtune.