From: iverson AT cisco DOT com (Tim Iverson) Subject: Re: alignment of common blocks 8 Aug 1997 23:59:09 -0700 Approved: cygnus DOT gnu-win32 AT cygnus DOT com Distribution: cygnus Message-ID: <199708090556.WAA11664.cygnus.gnu-win32@stars.cisco.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Original-To: lfm AT pgroup DOT com (Larry Meadows) Original-Cc: gnu-win32 AT cygnus DOT com In-Reply-To: <199708090054.RAA24261@pacific.pgroup.com> from "Larry Meadows" at Aug 8, 97 05:54:36 pm X-Mailer: ELM [version 2.4 PL25] Original-Sender: owner-gnu-win32 AT cygnus DOT com You can align an entire section using various ldscript options. Also, -malign-double can be used to set the default alignment to 8 bytes for double, long double, and long long. I don't know whether Cygnus compiled this option into the default release. The stack pointer is almost always kept aligned on a 4 byte boundary unless someone makes a mistake (3,2,&1 do work, but slow the system). I don't know what effect, if any, -malign-double has on automatic doubles. If you do recompile from scratch, changing default alignments for the various blocks is just a header change. Don't remember which one off the top, though ... somewhere in gcc/config. Hope this helps, - Tim Iverson iverson AT cisco DOT com +---------------- | Subject: alignment of common blocks | To: gnu-win32 AT cygnus DOT com | Date: Fri, 8 Aug 1997 17:54:36 -0700 (PDT) | From: Larry Meadows | | For performance reasons, we would like to be able to control the | alignment of common blocks (.comm name,size). We'd probably like to | be able to control the alignment of local common blocks (.lcomm name,size) .... | Finally, another question -- what is the default alignment of the stack? | | This is all important to get good performance on double precision stuff | on pentium, pentium pro, and later, as well as to allow users control | based on cache line size. | | Regards, | | Larry Meadows | lfm AT pgroup DOT com - For help on using this list (especially unsubscribing), send a message to "gnu-win32-request AT cygnus DOT com" with one line of text: "help".