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Re: asm, 'r' constraint, floating point registers?
- To: Zack Weinberg <zack at codesourcery dot com>
- Subject: Re: asm, 'r' constraint, floating point registers?
- From: Richard Henderson <rth at redhat dot com>
- Date: Thu, 11 Oct 2001 09:38:26 -0700
- Cc: gcc at gcc dot gnu dot org
- References: <20011011084357.B9432@codesourcery.com>
On Thu, Oct 11, 2001 at 08:43:57AM -0700, Zack Weinberg wrote:
> I've been talking off list with a user about his asm() problems and
> discovered something odd.
>
> If you write
>
> int n;
> asm ("frob %0" : "+r" (n));
>
> one would generally expect n not to be put into a floating point
> register. The user insists this is what happens. Is this
> (a) a bug in his port, (b) a bug in the machine-independent code, or
> (c) expected behavior which must be avoided somehow? I must confess I
> don't know where to begin looking.
"In his port"? So this isn't x86 or something? If so,
it's probably a bug in the definition of the register
classes.
r~