From patchwork Wed Sep 19 20:00:20 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aurelien Jarno X-Patchwork-Id: 185208 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 8DF092C008D for ; Thu, 20 Sep 2012 06:00:42 +1000 (EST) Received: from localhost ([::1]:50888 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TEQRs-0003bw-Gl for incoming@patchwork.ozlabs.org; Wed, 19 Sep 2012 16:00:40 -0400 Received: from eggs.gnu.org ([208.118.235.92]:42082) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TEQRi-0003bl-Nv for qemu-devel@nongnu.org; Wed, 19 Sep 2012 16:00:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TEQRg-0002C9-R3 for qemu-devel@nongnu.org; Wed, 19 Sep 2012 16:00:30 -0400 Received: from hall.aurel32.net ([88.191.126.93]:52041) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TEQRg-00028u-Iy 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-00052S-0q; Wed, 19 Sep 2012 22:00:27 +0200 Received: from aurel32 by ohm.aurel32.net with local (Exim 4.80) (envelope-from ) id 1TEQRd-0004p1-AV; Wed, 19 Sep 2012 22:00:25 +0200 From: Aurelien Jarno To: qemu-devel@nongnu.org Date: Wed, 19 Sep 2012 22:00:20 +0200 Message-Id: <1348084823-18277-7-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 6/9] tcg/optimize: optimize "op r, a, a => movi r, 0" 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 Now that it's possible to detect copies, we can optimize the case the "op r, a, a => movi r, 0". This helps the computation of overflow flags when one of the two args is 0. Signed-off-by: Aurelien Jarno Reviewed-by: Richard Henderson --- tcg/optimize.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/tcg/optimize.c b/tcg/optimize.c index cfee690..f8423e0 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -519,6 +519,23 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, break; } + /* Simplify expression for "op r, a, a => movi r, 0" cases */ + switch (op) { + CASE_OP_32_64(andc): + CASE_OP_32_64(sub): + CASE_OP_32_64(xor): + if (temps_are_copies(args[1], args[2])) { + gen_opc_buf[op_index] = op_to_movi(op); + tcg_opt_gen_movi(gen_args, args[0], 0); + gen_args += 2; + args += 3; + continue; + } + break; + default: + break; + } + /* Propagate constants through copy operations and do constant folding. Constants will be substituted to arguments by register allocator where needed and possible. Also detect copies. */