From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13233 invoked by alias); 23 Apr 2003 20:23:40 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 13215 invoked from network); 23 Apr 2003 20:23:39 -0000 Received: from unknown (HELO d12lmsgate.de.ibm.com) (194.196.100.234) by sources.redhat.com with SMTP; 23 Apr 2003 20:23:39 -0000 Received: from d12relay02.de.ibm.com (d12relay02.de.ibm.com [9.165.215.23]) by d12lmsgate.de.ibm.com (8.12.9/8.12.8) with ESMTP id h3NKNVu9037346; Wed, 23 Apr 2003 22:23:32 +0200 Received: from d12ml028.de.ibm.com (d12ml028_cs0 [9.165.223.24]) by d12relay02.de.ibm.com (8.12.8/NCO/VER6.5) with ESMTP id h3NKNVO1237270; Wed, 23 Apr 2003 22:23:31 +0200 Importance: Normal Sensitivity: Subject: Re: Profiling on S390 To: Richard Henderson Cc: Jan Hubicka , gcc@gcc.gnu.org, aj@suse.de Message-ID: From: "Ulrich Weigand" Date: Wed, 23 Apr 2003 21:50:00 -0000 MIME-Version: 1.0 Content-type: text/plain; charset=us-ascii X-SW-Source: 2003-04/txt/msg01188.txt.bz2 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