From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-patches-return-333835-listarch-gcc-patches=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 27725 invoked by alias); 9 Dec 2012 13:50:17 -0000
Received: (qmail 27712 invoked by uid 22791); 9 Dec 2012 13:50:15 -0000
X-SWARE-Spam-Status: No, hits=-4.3 required=5.0	tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,KHOP_RCVD_TRUST,RCVD_IN_DNSWL_LOW,RCVD_IN_HOSTKARMA_YE
X-Spam-Check-By: sourceware.org
Received: from mail-ob0-f175.google.com (HELO mail-ob0-f175.google.com) (209.85.214.175)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sun, 09 Dec 2012 13:50:12 +0000
Received: by mail-ob0-f175.google.com with SMTP id vb8so1706707obc.20        for <gcc-patches@gcc.gnu.org>; Sun, 09 Dec 2012 05:50:10 -0800 (PST)
MIME-Version: 1.0
Received: by 10.182.212.2 with SMTP id ng2mr1838967obc.81.1355061010274; Sun, 09 Dec 2012 05:50:10 -0800 (PST)
Received: by 10.182.153.201 with HTTP; Sun, 9 Dec 2012 05:50:10 -0800 (PST)
Date: Sun, 09 Dec 2012 13:50:00 -0000
Message-ID: <CAFULd4Z4hGXfjF-VXdazsnSQpnBszLxQidaVVOsZddZx0ep69w@mail.gmail.com>
Subject: Re: [PATCH i386]: Enable push/pop in pro/epilogue for modern CPUs
From: Uros Bizjak <ubizjak@gmail.com>
To: gcc-patches@gcc.gnu.org
Cc: Xinliang David Li <davidxl@google.com>
Content-Type: text/plain; charset=ISO-8859-1
Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-patches.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
List-Post: <mailto:gcc-patches@gcc.gnu.org>
List-Help: <mailto:gcc-patches-help@gcc.gnu.org>
Sender: gcc-patches-owner@gcc.gnu.org
X-SW-Source: 2012-12/txt/msg00577.txt.bz2

Hello!

> I noticed in prologue/epilogue, GCC prefers to use MOVs followed by a
> SP adjustment instead of a sequence of pushes/pops. The preference to
> the MOVs are good for old CPU micro-architectures (before pentium-4,
> K10), because it breaks the data dependency.  In modern
> micro-architecture, push/pop is implemented using a mechanism called
> stack engine. The data dependency is removed by the hardware, and
> push/pop becomes very cheap (1 uOp, 1 cycle latency), and they are
> smaller. There is no longer the need to avoid using them.   This is
> also what ICC does.

> 2012-12-08  Xinliang David Li  <davidxl@google.com>
>            * config/i386/i386.c: Eanble push/pop in pro/epilogue for moderen CPUs.

s/moderen/modern

OK for mainline SVN.

Thanks,
Uros.