From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24601 invoked by alias); 28 Oct 2005 21:29:28 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 24526 invoked by alias); 28 Oct 2005 21:29:19 -0000 Date: Fri, 28 Oct 2005 21:29:00 -0000 Message-ID: <20051028212919.24525.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug gcov/profile/24487] [3.4/4.0/4.1 Regression] Basic block frequencies inaccurate In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "hubicka at ucw dot cz" X-SW-Source: 2005-10/txt/msg03707.txt.bz2 List-Id: ------- Comment #4 from hubicka at ucw dot cz 2005-10-28 21:29 ------- Subject: Re: [Bug gcov/profile/24487] [3.4/4.0/4.1 Regression] Basic block frequencies inaccurate > > > ------- Comment #3 from dje at gcc dot gnu dot org 2005-10-28 17:30 ------- > The misprediction causes (or at least contributes to) compute_alignments in > final.c not aligning the critical loop in longest_match. The recent changes to > bb-reorder.c moved the start of the loop from an ideal alignment to the worst > alignment, causing a 8-10% performance drop due to instruction fetch problems. > Without the explicit alignment directives omitted because of misprediction, the > alignment of the loop is random. I see, Athlon is less sensitive to alignment that might explain it. I will try to fix my SPEC testing setup on PPC after SVN revamp and benchmark it there too... Honza > > > -- > > dje at gcc dot gnu dot org changed: > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |dberlin at gcc dot gnu dot > | |org > > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24487 > > ------- You are receiving this mail because: ------- > You are on the CC list for the bug, or are watching someone who is. > You are the assignee for the bug, or are watching the assignee. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24487