[EMAIL PROTECTED] (Richard Kenner) wrote on 16/03/2005 17:27:59:
> REG_NOTE (NONNEG)
> REG_NOTE (NO_CONFLICT)
> REG_NOTE (UNUSED)
> mustn't be copied
> describe a fact about other instructions so this
> may change if copied.
>
> Tricky. Often UNUSED means that we're allocating a psuedo for some
temporary
> which we know isn't used.
I suppose this is a function level information - meaning: the rgister is
not used all over the
function- so we can (and should) copy it.
>
> REG_NOTE (CC_SETTER)
> REG_NOTE (CC_USER)
> I suppose that using CC0 is possible only in branch
> instructions (correct
> me if I am wrong)
>
> It can also be used in "scc" insns.
This is interesting, so there could be cases were want to copy CC register
when doing SMS. what happens if we want to move the set of a CC to
another iteration of the loop ? or the use of the CC ?
but usually this is couldn't happen in a simple loop, right? the use of CC
is
eventually used in a branch, or there is something that I am missing ?
