Re: [B2-devel] [ANN] Basilisk II JIT snapshot 2004/11/09

[Gwenole B. <gb...@di...>]

mercredi 10 novembre 2004, =E0 09:37  am, Bob Deblier a =E9crit :

> The lines in question are:
> #APP
>         push %eax; popf; bsf %esi,%esi; pushf; pop %eax
> #NO_APP

Oh, I see. I hadn't merged this bit from the very old prototype system.=20=

;-)

> Splitting the assembler over multiple lines shows that it's the push %
> eax and pop %eax; tried fixing it with pushl and popl but that didn't=20=

> do
> the trick. Can 64-bit mode only push 64-bit quantities onto the stack?

Yes.

Besides, 64-bit mode doesn't handle sahf/lahf, thus yielding a typical=20=

15% performance decrease when you have to use the pushf/pop variants to=20=

get native flags (noticed on a Pentium 4). Fortunately, upcoming AMD64=20=

processors will now bring sahf/lahf back to 64-bit mode too. But it=20
seems Intel doesn't plan to implement them. i.e. there will be another=20=

bit in some cpuid level to report this support.=