From patchwork Wed Sep 19 20:00:22 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aurelien Jarno X-Patchwork-Id: 185214 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 916512C0085 for ; Thu, 20 Sep 2012 06:02:04 +1000 (EST) Received: from localhost ([::1]:58264 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TEQTC-0007Xe-Jt for incoming@patchwork.ozlabs.org; Wed, 19 Sep 2012 16:02:02 -0400 Received: from eggs.gnu.org ([208.118.235.92]:42160) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TEQRq-0003rE-US for qemu-devel@nongnu.org; Wed, 19 Sep 2012 16:00:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TEQRg-0002CE-R9 for qemu-devel@nongnu.org; Wed, 19 Sep 2012 16:00:38 -0400 Received: from hall.aurel32.net ([88.191.126.93]:52045) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TEQRg-0002AG-LD for qemu-devel@nongnu.org; Wed, 19 Sep 2012 16:00:28 -0400 Received: from [2001:470:d4ed:1:2db:dfff:fe14:52d] (helo=ohm.aurel32.net) by hall.aurel32.net with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.72) (envelope-from ) id 1TEQRf-00052U-Fw; Wed, 19 Sep 2012 22:00:27 +0200 Received: from aurel32 by ohm.aurel32.net with local (Exim 4.80) (envelope-from ) id 1TEQRd-0004pC-Dz; Wed, 19 Sep 2012 22:00:25 +0200 From: Aurelien Jarno To: qemu-devel@nongnu.org Date: Wed, 19 Sep 2012 22:00:22 +0200 Message-Id: <1348084823-18277-9-git-send-email-aurelien@aurel32.net> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1348084823-18277-1-git-send-email-aurelien@aurel32.net> References: <1348084823-18277-1-git-send-email-aurelien@aurel32.net> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 88.191.126.93 Cc: Aurelien Jarno Subject: [Qemu-devel] [PATCH 8/9] tcg/optimize: prefer the "op a, a, b" form for commutative ops X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org The "op a, a, b" form is better handled on non-RISC host than the "op a, b, a" form, so swap the arguments to this form when possible, and when b is not a constant. This reduces the number of generated instructions by a tiny bit. Signed-off-by: Aurelien Jarno Reviewed-by: Richard Henderson --- tcg/optimize.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tcg/optimize.c b/tcg/optimize.c index 6e2a37d..3495b7a 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -432,7 +432,10 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, CASE_OP_32_64(eqv): CASE_OP_32_64(nand): CASE_OP_32_64(nor): - if (temps[args[1]].state == TCG_TEMP_CONST) { + /* Prefer the constant in second argument, and then the form + op a, a, b, which is better handled on non-RISC hosts. */ + if (temps[args[1]].state == TCG_TEMP_CONST || (args[0] == args[2] + && temps[args[2]].state != TCG_TEMP_CONST)) { tmp = args[1]; args[1] = args[2]; args[2] = tmp;