Re: default CPU target ix86 based ports

[Matthias Klose <doko@cs.tu-berlin.de>]

Nathanael Nerode writes:
> Matthias Klose wrote:
> >so make -mcpu=i586 -mtune=i686 the default? anything else as the 
> >default?
> 
> Just to clarify, that would be the default for *hurd* only, right?

yes

> There's no good reason to drop 486 support under Linux. So for Linux, 
> it would be -mcpu=i486 -mtune-i686 as the default, correct?

yes, except gcc-3.3 doesn't have -mtune. So this should be -mcpu=i686
-march=486. Looking at config.gcc the TARGET_CPU_DEFAULT is
overwritten by the target_alias. Looking at i386.c:1038 the cpu string
(tuning) is set to the TARGET_DEFAULT, but the arch string remains at
i386. the correct way to tune for i686 and use insn for i486 seems to
be this one. do you agree?

--- gcc/config/i386/i386.c~     2003-07-09 07:45:00.000000000 +0200
+++ gcc/config/i386/i386.c      2003-08-09 12:58:33.000000000 +0200
@@ -1038,9 +1038,9 @@
   if (!ix86_cpu_string && ix86_arch_string)
     ix86_cpu_string = ix86_arch_string;
   if (!ix86_cpu_string)
-    ix86_cpu_string = cpu_names [TARGET_CPU_DEFAULT];
+    ix86_cpu_string = cpu_names [TARGET_CPU_DEFAULT_pentiumpro];
   if (!ix86_arch_string)
-    ix86_arch_string = TARGET_64BIT ? "athlon-4" : "i386";
+    ix86_arch_string = TARGET_64BIT ? "athlon-4" : "i486";
 
   if (ix86_cmodel_string != 0)
     {