From patchwork Fri Jan 24 10:27:01 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13949236 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4E753C02181 for ; Fri, 24 Jan 2025 10:27:50 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tbGuE-0005pM-4k; Fri, 24 Jan 2025 05:27:18 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tbGuB-0005p7-Df for qemu-devel@nongnu.org; Fri, 24 Jan 2025 05:27:15 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tbGu9-000180-O0 for qemu-devel@nongnu.org; Fri, 24 Jan 2025 05:27:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1737714428; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=L6M9+1mO2prFuonNAkKygGF6aqmKLUzZSktg2cRQ66U=; b=VR/FGnkZAkwGu4plkgfJkmHL6XqNOkelMkmVfolwUQ/Z0Ywm5fjGqK90EOu2TIm55/HngT jf7WWUhHx8bz3rbgOLF1xDmj09MjO1XsJrMOnmk2bB5c/aklj4Nu0BrvOgN7l3WmZ4pjDQ kVr9ILqgIRPe/h4FgK9ovxICojvCiWQ= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-1-LUD-XPW1OjGF2lLfM1HlRg-1; Fri, 24 Jan 2025 05:27:06 -0500 X-MC-Unique: LUD-XPW1OjGF2lLfM1HlRg-1 X-Mimecast-MFC-AGG-ID: LUD-XPW1OjGF2lLfM1HlRg Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-43628594d34so10564105e9.2 for ; Fri, 24 Jan 2025 02:27:06 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1737714424; x=1738319224; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=L6M9+1mO2prFuonNAkKygGF6aqmKLUzZSktg2cRQ66U=; b=tLgbtEaaEeMtsu1v+hOFZp224UXj6kK4FWZM8gXDFzz7NdCBld+vXu/AzBdhDgl639 QXnPJN9G59lSV/ykQNFoT8kq1NXsta12ZBjzx8ex+gFRXkKxaojNh4OnonGP3O+ppB0Y fcmj20d+xpDLJmnXmX+W9XyW0beqsH32eYgtTwtGdkHvbuN9t+BUlyZAWCy6m8XHc7ve syMk33xJ6ZIPtMMb3dad6FBRpikhWue2Syyd1RQymoerD8KaQ6SmzGS1i7JWGEXzUPyU 8pNH7xKnNcIhyOmgEVdu07imBdEYorCcSe+QYuu97/bLwLIQozPMg0OYMy9ohraBegNs i4OQ== X-Gm-Message-State: AOJu0YxMZSJlxR5SSeJ1VcIP8H2+jzNNvZeKnRj+/0eu6E7xn8ElBwYh RzAVf15onp2D6ruqzeyo1G+Q9kFLFt8Tsu8sZ7ecuudXqz3idXBAOYsbJ/nQGkpqrYApSJu8ZIX XdM20OyIUJGGRBqdl5+kXL+qMPJNRJpZxAz5yHykOmYlGDCepExgoew9jeYd6S4DXywHX1Sj07q R7kwn0RALKXDbot0x/tYahBVN0RaSoFpVdx6LeAMg= X-Gm-Gg: ASbGncvHkJwT5uaQ352krTpSbFWPr+2rLZwORy4it9D+DjJ+t7Qt1JRikjJ/NLRTWck 3Kc0iaeDK7FoQjeDxBLa2XSswp+6ptaGc4pbLd2Nuxwrq8QxltbxXti+EOcxwQ5LWqxZB0gLa28 8fYkBaeSkiOBn9o/W/4ytcHj1Gt4c2wF3qdrt3gMji3Bj4MO31rYxk9Wp9n56x4njQMmEIQH4TE xeF5Hr4NIMqB2EX28X/hek4CT1M+Oyb6lGDbldkFPg5iWBjwhE9KulakmKMBrI6x9CyZ/fn X-Received: by 2002:a05:600c:4fc1:b0:437:c3a1:5fe7 with SMTP id 5b1f17b1804b1-438914340a4mr244288075e9.20.1737714424209; Fri, 24 Jan 2025 02:27:04 -0800 (PST) X-Google-Smtp-Source: AGHT+IGPj8DKVCPV4seAiQQDq0hoLYJe2hprURwyWt500BtvcPBO7TATGgpLW2sVdb7yZaVkZnvvRA== X-Received: by 2002:a05:600c:4fc1:b0:437:c3a1:5fe7 with SMTP id 5b1f17b1804b1-438914340a4mr244287795e9.20.1737714423811; Fri, 24 Jan 2025 02:27:03 -0800 (PST) Received: from [192.168.10.3] ([151.95.59.125]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-438bd4fa57csm22147675e9.4.2025.01.24.02.27.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Jan 2025 02:27:03 -0800 (PST) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: richard.henderson@linaro.org Subject: [PATCH v2] tcg/optimize: optimize TSTNE using smask and zmask Date: Fri, 24 Jan 2025 11:27:01 +0100 Message-ID: <20250124102701.225307-1-pbonzini@redhat.com> X-Mailer: git-send-email 2.48.1 MIME-Version: 1.0 Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.996, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Generalize the existing optimization of "TSTNE x,sign" and "TSTNE x,-1". This can be useful for example in the i386 frontend, which will generate tests of zero-extended registers against 0xffffffff. Ironically, on x86 hosts this is a very slight pessimization in the very case it's meant to optimize because brcond_i64 cc_dst,$0xffffffff,tsteq,$L1 (test %ebx, %ebx) is 1 byte smaller than brcond_i64 cc_dst,$0x0,eq,$L1 (test %rbx, %rbx). However, in general it is an improvement, especially if it avoids placing a large immediate in the constant pool. Signed-off-by: Paolo Bonzini --- tcg/optimize.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/tcg/optimize.c b/tcg/optimize.c index c23f0d13929..a509acf53fe 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -112,6 +112,13 @@ static inline bool arg_is_const_val(TCGArg arg, uint64_t val) return ts_is_const_val(arg_temp(arg), val); } +/* Calculate all the copies of the sign bit, both redundant and not. */ +static inline uint64_t all_sign_bit_copies(TCGType type, TempOptInfo *info) +{ + int64_t sign_bit = type == TCG_TYPE_I32 ? (int64_t)INT32_MIN : INT64_MIN; + return (info->s_mask >> 1) | sign_bit; +} + static inline bool ts_is_copy(TCGTemp *ts) { return ts_info(ts)->next_copy != ts; @@ -765,6 +772,7 @@ static int do_constant_folding_cond1(OptContext *ctx, TCGOp *op, TCGArg dest, TCGArg *p1, TCGArg *p2, TCGArg *pcond) { TCGCond cond; + TempOptInfo *i1; bool swap; int r; @@ -782,19 +790,22 @@ static int do_constant_folding_cond1(OptContext *ctx, TCGOp *op, TCGArg dest, return -1; } + i1 = arg_info(*p1); + /* * TSTNE x,x -> NE x,0 - * TSTNE x,-1 -> NE x,0 + * TSTNE x,i -> NE x,0 if i includes all nonzero bits of x */ - if (args_are_copies(*p1, *p2) || arg_is_const_val(*p2, -1)) { + if (args_are_copies(*p1, *p2) || + (arg_is_const(*p2) && (i1->z_mask & ~arg_info(*p2)->val) == 0)) { *p2 = arg_new_constant(ctx, 0); *pcond = tcg_tst_eqne_cond(cond); return -1; } - /* TSTNE x,sign -> LT x,0 */ - if (arg_is_const_val(*p2, (ctx->type == TCG_TYPE_I32 - ? INT32_MIN : INT64_MIN))) { + /* TSTNE x,i -> LT x,0 if i only includes sign bit copies */ + if (arg_is_const(*p2) && + (arg_info(*p2)->val & ~all_sign_bit_copies(ctx->type, i1)) == 0) { *p2 = arg_new_constant(ctx, 0); *pcond = tcg_tst_ltge_cond(cond); return -1;