Re: Does -march=r5000 imply HAVE_64BIT_GPRS?

["H . J . Lu" <hjl at lucon dot org>]

On Fri, Aug 17, 2001 at 08:10:27PM +0200, Thiemo Seufer wrote:
> > 
> > Only for BFD, not for assembler. Besides, when -mips2 is used with
> > -march=r5000, the assembler shouldn't use any instructions which are
> > in r5000, but not in MISP II.
> 
> Well, now I can reiterate my question: Why shouldn't it do so?
> 
> Of course, in the case of r5000 this makes no difference since it
> has no insns which aren't covered by an ISA (WRT binutils). An
> example might be the VR4100: Restrict it to MIPS II but use it's
> "standby" and "suspend" opcodes. With runtime CPU detection it is
> easy to find a scenario where this makes sense.
> 

There are several problems:

1. When -mips2 is passed to as, should anything beyond MIPS II be
generated? My answer is no.
2. Assuming we do allow extra insns beyond MIPS II, what value should
be in EF_MIPS_ARCH? bfd_set_arch_mach is used to set EF_MIPS_ARCH.

In my opinion, if we do allow extra insns beyond MIPS II, we should
add a call to set EF_MIPS_MACH. That should be orthogonal to
EF_MIPS_ARCH. One way to do it to add

bfd_mach_mips1
bfd_mach_mips2
bfd_mach_mips3
bfd_mach_mips4

and we can do

bfd_set_arch_mach (stdoutput, bfd_arch_mips,
		   bfd_mach_mips2 | bfd_mach_mips4100);

We use bfd_mach_mips2 to set EF_MIPS_ARCH and bfd_mach_mips4100 to
set EF_MIPS_ARCH.


H.J.