Re: Why Plan 9 C compilers don't have asm("")

[Rick Hohensee <humbubba@smarty.smart.net>]

>Victor Yodaiken <yodaiken@fsmlabs.com>
>
>I think anywhere that you have inner loop or often used operations
>that are short assembler sequences, inline asm is a win - it's easy to
>show for example, that the Linux asm x86  macro semaphore down
>is three times as fast as
>a called version. I wish, however
>that GCC did not use a horrible overly complex lisplike syntax and
>that there was a way to inline functions written in .S files.

If you can loop faster in asm, and you surely can on x86/Gcc in many
cases, that's a win, and probably quite a worthwhile one, but that's
independant of inline in terms of "not a C call". I think that distinction
may be prone to being overlooked. The longer your average loop, the less
asm("") matters, i.e. the less of a proportional hit a C stack ceremony
is. You can loop in asm and still not need asm(""), if you pay for the
stack frame. Plan 9 has about 4 string functions that are hand-coded, but
they are C-called, from what I can tell, and have been told.

Rick Hohensee
		www.clienux.com