Hi,
> > I want:
> >
> > 1. use the code which I posted as an inline, but I don't know how to inline
> > it correctly
>
> There is a complete worked example just here, that Ian posted, with almost
> exactly the same arguments. Can't you use it as a model?
Could you please modify it for me? I tryed myself, but I do something wrong.
I can benchmark the code on the real 68060 (GCC inline vs code posted by me)
with FFmpeg, so this will be a real life test.
> > 2. if the code is faster already with FFmpeg as an external link object, it
> > will be even faster when inlined, so maybe default GCC code should be repleaced with code I
> > posted?
>
> Sure, but first we need to know why the code you posted is faster. I can't
> immediately see why it should be.
>
> Maybe it's something to do with sign extension. It's possible that gcc doesn't
> use the umul_ppmm inline that Ian posted because you sign extend both args
> before multiplying.
>
> This can easily be worked around, but we need to see the code gcc generates.
#include <stdint.h>
inline int MULH(int a, int b){
return ((int64_t)(a) * (int64_t)(b))>>32;
}
Here is asm output (GCC 4.4.0):
#NO_APP
.text
.even
.globl _MULH
_MULH:
move.l d3,-(sp)
move.l d2,-(sp)
move.l 12(sp),d1
smi d0
extb.l d0
move.l 16(sp),d3
smi d2
extb.l d2
move.l d2,a0
move.l d3,a1
move.l a1,-(sp)
move.l a0,-(sp)
move.l d1,-(sp)
move.l d0,-(sp)
jsr ___muldi3
lea (16,sp),sp
move.l d0,d1
smi d0
extb.l d0
move.l d1,d0
move.l (sp)+,d2
move.l (sp)+,d3
rts
Regards
