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

To: Thiemo Seufer <>
Subject: Re: Q: -mcpu= vs. -march= for VR41xx specific instructions
From: Johannes Stezenbach <>
Date: Thu, 14 Mar 2002 19:34:32 +0100
In-reply-to: <>
Mail-followup-to: Johannes Stezenbach <>, Thiemo Seufer <>,
References: <> <>
User-agent: Mutt/1.3.27i
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.


> 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?


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