Re: [f-cpu] ll/sc

[Yann Guidon <whygee@f-cpu.org>]

hi,

i don't read much the f-cpu mails these days...
but...

> Christophe Avoinne wrote:
> 
> Another possibility :
> 
> loopentry r3
> ...
> lload    r1,[r2] --> r1 = *r2; lock LSU entry
> ...
> lstore   r1,[r2],r3 --> if locked, *r2 = r1, unlock LSU entry.
>                              if not, jump to r3

no <- the jump destination can only be in R2.

> we jump instead of setting false a register when
> we cannot store because the lock is discarded in the LSU entry.
> 
> The only interest to do so, is to reduce instructions since
> we can expect having a conditional jumping after a failed lstore.
> 
> But the counterpart is that you cannot sandwitch some
> instructions between lstore and conditional jump or
> just want to jump when lstore suceeds.

The instruction format problem is much more important and makes
this approach impossible. sorry.

WHYGEE
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