From: Jamie Prescott <jpresss@yahoo.com>
To: Paolo Bonzini <bonzini@gnu.org>
Cc: gcc@gcc.gnu.org
Subject: Re: Code generation problem with optimizations enabled
Date: Tue, 12 May 2009 16:39:00 -0000 [thread overview]
Message-ID: <409399.95849.qm@web111610.mail.gq1.yahoo.com> (raw)
In-Reply-To: <4A0933F9.6080006@gnu.org>
Thank you Paolo, I'll take a look at it.
Is there a reason why the fcmp insn was dropped with such implementation?
- Jamie
----- Original Message ----
> From: Paolo Bonzini <bonzini@gnu.org>
> To: Jamie Prescott <jpresss@yahoo.com>
> Cc: gcc@gcc.gnu.org
> Sent: Tuesday, May 12, 2009 1:31:53 AM
> Subject: Re: Code generation problem with optimizations enabled
>
> > What I noticed is that if I CC_STATUS_INIT (in xxx_notice_update_cc()) even
> for insn that
> > do not require it (that are almost all of them - being only cmp/fcmp/test that
> modify cc0),
> > cmpdf gets emitted regularly.
>
> If so, you should not be using cc0, but a CCmode register instead.
>
> See for example how the fr30 port implements compare-and-jump. I'm
> currently committing a merge that changes a bit how the
> compare-and-jumps are realized; if you wait a few hours, you'll get a
> more up-to-date example.
>
> Paolo
next prev parent reply other threads:[~2009-05-12 15:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-12 8:09 Jamie Prescott
2009-05-12 8:31 ` Jamie Prescott
2009-05-12 9:28 ` Paolo Bonzini
2009-05-12 16:39 ` Jamie Prescott [this message]
2009-05-14 3:54 ` Jim Wilson
2009-05-14 11:14 ` Jamie Prescott
2009-05-12 17:54 ` Jamie Prescott
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