From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24248 invoked by alias); 4 Oct 2011 03:44:54 -0000 Received: (qmail 24226 invoked by uid 22791); 4 Oct 2011 03:44:53 -0000 X-SWARE-Spam-Status: No, hits=-2.1 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,TW_JL,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: sourceware.org Received: from mail-wy0-f175.google.com (HELO mail-wy0-f175.google.com) (74.125.82.175) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 04 Oct 2011 03:44:36 +0000 Received: by wyh5 with SMTP id 5so72202wyh.20 for ; Mon, 03 Oct 2011 20:44:35 -0700 (PDT) MIME-Version: 1.0 Received: by 10.216.14.2 with SMTP id c2mr4581895wec.30.1317699875565; Mon, 03 Oct 2011 20:44:35 -0700 (PDT) Received: by 10.216.168.10 with HTTP; Mon, 3 Oct 2011 20:44:35 -0700 (PDT) In-Reply-To: References: <201110031834.35051.vapier@gentoo.org> <201110031903.43037.vapier@gentoo.org> Date: Tue, 04 Oct 2011 03:44:00 -0000 Message-ID: Subject: Re: new triplet for x32 psABI? From: Michael LIAO To: x32-abi@googlegroups.com Cc: Mike Frysinger , autoconf@gnu.org, gcc@gcc.gnu.org, config-patches@gnu.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2011-10/txt/msg00035.txt.bz2 On Mon, Oct 3, 2011 at 5:53 PM, H.J. Lu wrote: > On Mon, Oct 3, 2011 at 4:47 PM, Michael LIAO wr= ote: >> On Mon, Oct 3, 2011 at 4:03 PM, Mike Frysinger wrote: >>> On Monday, October 03, 2011 18:57:28 Michael LIAO wrote: >>> >>> please don't top post >>> >> >> sorry, it's my first post on mailing. >> >>>> Most examples would be related to tools generating code. >>>> >>>> Suppose you have a software package with several hard-coded fully >>>> optimized assembly file for different targets. Your build system need >>>> to know the current target as well as target ABI to select the correct >>>> assembly file to build it. It even desirable if it includes a simple >>>> script to help generate assembly code (like the one in OpenSSL), you'd >>>> better know the target ABI to prepare proper glue code without >>>> breaking ABI. >>> >>> hjlu posted examples to the x32 site as to handle this. =C2=A0the only = difference >>> between x86_64 and x32 is the size of the pointers. >>> >> >> Besides the pointer size, there are other differences like indirect >> branch which need different code sequence on x32 and x64. Indirect >> branch would be used in assembly code (yeah, concrete example would >> valuable here but indirect branch should be used potentially and >> possibly in assembly code.) If the assembly code use indirect branch, >> it needs to know the target ABI and generate/use difference code path. >> > > In assembly codes, most, if not all, of x86-64 indirect branch work fine = for x32 > that may cause the target IP out of the first 4G range if assembly code won't follow x32 abi, e.g. indirect target is stored in a memory location and assembly direct use 64-bit near absolute indirect call with m64 opernad since the branch target is 32 bits in memory but that call will read 64-bit value and result in garbage on high 32 bits of the final IP. > > -- > H.J. >