Patch for md.texi: Fix i386 constraints
Richard Henderson
rth@redhat.com
Mon Apr 23 14:18:00 GMT 2001
On Sun, Apr 22, 2001 at 02:04:17PM +0200, Andreas Jaeger wrote:
> > GCC may use any register pair to hold 64bit values on 32bit system
[...]
> Are you sure? In glibc we often do:
> __asm__ __volatile__ ("rdtsc" : "=A" (Var))
> and rdtsc puts the value in ax:dx. The current description is misleading.
Yes, but your replacement is just as misleading.
> -@samp{a}, or @code{d} register (for 64-bit ints)
> +@samp{a} and @samp{d} register used together to store 64-bit ints. The
> +@samp{a} register will store the most significand 32-bits, the @samp{d}
> +register the least significand 32-bits.
How about
Specifies the @samp{a} or @samp{d} registers. This is primarily useful
for 64-bit integer values (when in 32-bit mode) intended to be returned
with @code{EDX} holding the most significant bits and @code{EAX} holding
the least significant bits.
r~
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