Re: [9fans] partial-Plan9ification question

[Mike Haertel <mike@ducky.net>]

>the plan 9 compilers are strictly caller-saves, for all architectures.  other details vary.
>on some platforms, a few useful constants are reserved in floating-point registers.
>
>gcc varies between architectures, and even from platform to platform,
>but i think even on the x86 with hardly any registers, some registers are callee-saved.

On x86 unix systems, eax, edx, and ecx are callee-saves, and the rest
are caller-saves.  eax and edx are used for return values.

For AMD's forthcoming x86-64, the gcc folks actually had the luxury
of being able to invent their own convention, rather than having
to follow a convention dictated to them by existing tools and
libraries.  They did some studies and ended up choosing about half
and half caller and callee saves.  I think there are slightly more
caller-saves registers.  They also went to some effort to pass a
few arguments in registers.  The down side is their conventions
appear hairy.

Just to keep this from drifting off Plan 9 entirely: any luck on
the 8c sign extension bug?