From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29936 invoked by alias); 16 May 2009 06:38:01 -0000 Received: (qmail 29890 invoked by uid 48); 16 May 2009 06:37:49 -0000 Date: Sat, 16 May 2009 06:38:00 -0000 Message-ID: <20090516063749.29889.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug target/39942] Nonoptimal code - leaveq; xchg %ax,%ax; retq In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "jakub at gcc dot gnu 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: 2009-05/txt/msg01376.txt.bz2 ------- Comment #45 from jakub at gcc dot gnu dot org 2009-05-16 06:37 ------- cmpl $1, %eax does have the modrm byte: 83 f8 01 cmp $0x1,%eax compared to cmpl $0xdeadbeef, $eax which doesn't have it: 3d ef be ad de cmp $0xdeadbeef,%eax So I think what I wrote is more precise. modrm byte is there if the insn has ax_reg_operand destination and immediate source which hasn't been shortened. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39942