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Re: condition codes, haifa-sched and virtual-stack-vars
- From: Ulrich Weigand <weigand at immd1 dot informatik dot uni-erlangen dot de>
- To: geoffk at geoffk dot org
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 31 Jan 2002 01:35:40 +0100 (MET)
- Subject: Re: condition codes, haifa-sched and virtual-stack-vars
Following up on myself:
> The reload_inhi pattern tries to allocate the carry register as the
> secondary reload scratch register. Now, in the interesting case
> where the carry register is in fact live at the location where the
> insn is inserted, this would mean that reload would need to spill
> the carry register and later on restore its old value, right?
> (Because there is only a single register in this class ...)
>
> However, I'm not sure how the carry register can be spilled,
> given that there is no mov* insn that touches it, unless I'm
> missing something ...
Hmm, what I was missing was that apparently the carry register
can *never* be live during reload, as all insns that actually
use it (except for just a clobber) are *only* ever emitted from
splitters after reload.
So what I called the 'interesting case' above never happens ...
Bye,
Ulrich
--
Dr. Ulrich Weigand
weigand@informatik.uni-erlangen.de