From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17058 invoked by alias); 29 Apr 2010 22:58:46 -0000 Received: (qmail 16965 invoked by uid 48); 29 Apr 2010 22:58:35 -0000 Date: Thu, 29 Apr 2010 22:58:00 -0000 Message-ID: <20100429225835.16964.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug rtl-optimization/40838] gcc shouldn't assume that the stack is aligned In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "dirtyepic at gentoo dot org" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2010-04/txt/msg03212.txt.bz2 ------- Comment #75 from dirtyepic at gentoo dot org 2010-04-29 22:58 ------- if some libraries, (zlib and fontconfig i've had personal experience with, i've also heard libgcrypt) are compiled with -ftree-vectorize (ie. -O3) on x86 systems supporting SSE2, it causes segfaults in certain packages, usually mozilla-based or wine, when SSE2 instructions requiring 16bit alignment are used on unaligned data. nothing is being built with -mpreferred-stack-boundary in these cases. this is PR41156, https://bugzilla.redhat.com/489290, https://bugs.gentoo.org/270120. i'm not convinced this is GCC's problem. it usually gets traced back as far as something in the mozilla codebase misaligning the stack at which point everyone seems to give up. i've yet to see an actual testcase, though I've encountered it several times in the wild. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838