From: "Ulrich Weigand" <Ulrich.Weigand@de.ibm.com>
To: Richard Henderson <rth@redhat.com>
Cc: Jan Hubicka <jh@suse.cz>, gcc@gcc.gnu.org, aj@suse.de
Subject: Re: Profiling on S390
Date: Wed, 23 Apr 2003 21:50:00 -0000 [thread overview]
Message-ID: <OF0AE7CC2A.662B03BB-ONC1256D11.006F098A@de.ibm.com> (raw)
Richard Henderson wrote:
>Document that AVOID_CCMODE_COPIES implies that the flags register
>cannot be live across basic blocks.
Why? I'd probably *want* to define AVOID_CCMODE_COPIES on s390,
because while we can save/restore the condition code to/from a
general purpose register, we really have just the single CC that
is actually usable for conditional branches, so it usually wouldn't
make sense for the optimizer to copy CCmode values around.
However, in the case of the profiler where saving/restoring CC
is vital for *correctness*, shouldn't the fact that CCmode copies
are *possible* (i.e. movcc works) be enough?
(B.t.w. we currently don't accept CCmode values in GPRs at all.
If I were to introduce that capability, does the common code make
any assumptions on just how those values are represented by integers?
Does (subreg:SI (reg:CC ...) 0) or vice versa work?)
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
--
Dr. Ulrich Weigand
Linux for S/390 Design & Development
IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
Phone: +49-7031/16-3727 --- Email: Ulrich.Weigand@de.ibm.com
next reply other threads:[~2003-04-23 20:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-23 21:50 Ulrich Weigand [this message]
2003-04-23 22:08 ` Richard Henderson
-- strict thread matches above, loose matches on Subject: below --
2003-04-23 18:18 Ulrich Weigand
2003-04-23 12:19 Ulrich Weigand
2003-04-22 22:34 Ulrich Weigand
2003-04-22 23:13 ` Richard Henderson
2003-04-23 10:59 ` Jan Hubicka
2003-04-23 18:26 ` Richard Henderson
2003-04-23 19:18 ` Jan Hubicka
2003-04-23 19:56 ` Richard Henderson
2003-04-23 21:29 ` Jan Hubicka
2003-04-23 22:33 ` Richard Henderson
2003-04-25 17:01 ` Jan Hubicka
2003-04-18 12:11 Jan Hubicka
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=OF0AE7CC2A.662B03BB-ONC1256D11.006F098A@de.ibm.com \
--to=ulrich.weigand@de.ibm.com \
--cc=aj@suse.de \
--cc=gcc@gcc.gnu.org \
--cc=jh@suse.cz \
--cc=rth@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).