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Re: SuperH: -m4-nofpu flag
- To: Alexandre Oliva <aoliva at redhat dot com>
- Subject: Re: SuperH: -m4-nofpu flag
- From: Philipp Rumpf <prumpf at mandrakesoft dot mandrakesoft dot com>
- Date: Thu, 15 Feb 2001 03:57:25 -0600 (CST)
- cc: NIIBE Yutaka <gniibe at m17n dot org>, gcc at gcc dot gnu dot org
On 15 Feb 2001, Alexandre Oliva wrote:
> On Feb 15, 2001, NIIBE Yutaka <gniibe@m17n.org> wrote:
>
> > In sh-elf, when -m4-nofpu is specified, __sh3__ (and __SH4_NOFPU__)
> > are defined. It looks weird for me to define __sh3__ for SH-4.
>
> > Is there any reason why __sh3__ is defined with -m4-nofpu in sh-elf?
>
> Well, the ISA of a FPU-less SH4 is pretty much the same as that of
> SH3.
The way Linux on SuperH uses this flag right now, it doesn't mean we're on
an FPU-less SH4; it means we're on a standard SH4 but don't want gcc to
generate FPU instructions (we do generate FPU instructions in inline
assembly though). There are, of course, many kernel-visible ISA
differences between SH4 and SH3 even if you don't take FPU insns into
account.
Wouldn't it make more sense to add something like -mdisable-fpregs and use
-m4 ?
Philipp Rumpf