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Re: [rx] add register-specific constraints
- From: DJ Delorie <dj at redhat dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 1 Nov 2010 14:13:08 -0400
- Subject: Re: [rx] add register-specific constraints
- References: <201010290558.o9T5whGR027913@greed.delorie.com> <4CCCB96D.6070201@redhat.com>
> Source-level asms can use registers. E.g.
>
> register int r1 __asm__("r1");
> asm ("" : "=r"(r1));
>
> That's guaranteed to not replace the hard register in the asm.
> Glibc and the linux kernel relies on this for a number of ports,
> so it's unlikely to ever break.
>
> Is there any other reason to add these?
Does that work for register pairs?