Re: Q: -mcpu= vs. -march= for VR41xx specific instructions

[Johannes Stezenbach <js@convergence.de>]

On Thu, Mar 14, 2002 at 07:10:31PM +0100, Thiemo Seufer wrote:
> Johannes Stezenbach wrote:
> >   GCCFLAGS += -Wa,-march=vr4100 -mips2 -Wa,--trap
> > 
> > This works, but I am unshure what the effects of the
> > missing -mcpu switch are wrt the code generated by gcc.
> > AFAICS the kernel still works, but is the generated
> > code slower or subtly incorrect?
> 
> I don't know what the compiler does then. I assume it defaults to
> r3000 scheduling/opcodes.

How bad is that compared to -mcpu=vr4100?

> I would suggest the syntax
> 
> 	.set march=vr4100
> 
> This is in my TODO list for gas, but don't hold your breath.

OK.

> The real fix is to use a newer compiler (gcc >= 3). :-)

Not too long ago people here told me that gcc 3.x is still
not ready for production use. Or is gcc-3.1-pre from CVS
ready for prime time?


Thanks,
Johannes