From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 6C8073858416 for ; Mon, 7 Nov 2022 19:59:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 6C8073858416 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667851145; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=mpZhslDQd/JYU27rP1Y0Zre1UkGbTkcp9HL5wZ42wHE=; b=OsFLcmYkCSBQj0aJXBVRSIAFMPMHuHVRyvRFXTTZZk0OF1y1nzjtAGhfev5DzmBNWKFT+9 Kp86geHq/t4Vi4gL7/9hhE554SbTgfws7lc8v671vBaOqT5hKQ5140mxrH8Z7zcmu1BiCp 6rZKWjE/FZxycaFSSf5FmachTZoy1wE= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-627-UqF7SrGTPo6q1ZNoFls94w-1; Mon, 07 Nov 2022 14:59:03 -0500 X-MC-Unique: UqF7SrGTPo6q1ZNoFls94w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 82A5D1C09C86 for ; Mon, 7 Nov 2022 19:59:03 +0000 (UTC) Received: from abulafia.quesejoda.com (unknown [10.39.192.96]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3ADDB1121314; Mon, 7 Nov 2022 19:59:02 +0000 (UTC) Received: from abulafia.quesejoda.com (localhost [127.0.0.1]) by abulafia.quesejoda.com (8.17.1/8.17.1) with ESMTPS id 2A7Jx0e9791457 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 7 Nov 2022 20:59:00 +0100 Received: (from aldyh@localhost) by abulafia.quesejoda.com (8.17.1/8.17.1/Submit) id 2A7Jx09E791451; Mon, 7 Nov 2022 20:59:00 +0100 From: Aldy Hernandez To: GCC patches Cc: Andrew MacLeod , Aldy Hernandez Subject: [COMMITTED] Improve multiplication by powers of 2 in range-ops. Date: Mon, 7 Nov 2022 20:58:56 +0100 Message-Id: <20221107195856.791257-1-aldyh@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-11.8 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: For unsigned numbers, multiplication by X, where X is a power of 2 is [0,0][X,+INF]. This patch causes a regression to g++.dg/pr71488.C where -Wstringop-overflow gets the same IL as before, but better ranges cause it to issue a bogus warning. I will create a PR with some notes. No discernible changes in performance. Tested on x86-64 Linux. PR tree-optimization/55157 gcc/ChangeLog: * range-op.cc (operator_mult::wi_fold): Optimize multiplications by powers of 2. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/pr55157.c: New test. --- gcc/range-op.cc | 16 ++++++++++++++-- gcc/testsuite/gcc.dg/tree-ssa/pr55157.c | 19 +++++++++++++++++++ 2 files changed, 33 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr55157.c diff --git a/gcc/range-op.cc b/gcc/range-op.cc index 25c004d8287..835b43fb747 100644 --- a/gcc/range-op.cc +++ b/gcc/range-op.cc @@ -1910,8 +1910,20 @@ operator_mult::wi_fold (irange &r, tree type, // diff = max - min prod2 = prod3 - prod0; if (wi::geu_p (prod2, sizem1)) - // The range covers all values. - r.set_varying (type); + { + // Multiplying by X, where X is a power of 2 is [0,0][X,+INF]. + if (TYPE_UNSIGNED (type) && rh_lb == rh_ub + && wi::exact_log2 (rh_lb) != -1 && prec > 1) + { + r.set (type, rh_lb, wi::max_value (prec, sign)); + int_range<2> zero; + zero.set_zero (type); + r.union_ (zero); + } + else + // The range covers all values. + r.set_varying (type); + } else { wide_int new_lb = wide_int::from (prod0, prec, sign); diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr55157.c b/gcc/testsuite/gcc.dg/tree-ssa/pr55157.c new file mode 100644 index 00000000000..bbdda45bd64 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr55157.c @@ -0,0 +1,19 @@ +// { dg-do compile } +// { dg-options "-O2 -fdump-tree-evrp" } + +void gg(void); +int f(unsigned t) +{ + unsigned g = t*16; + if (g==0) return 1; + gg(); + gg(); + gg(); + gg(); + gg(); + gg(); + if (g<=4) return 1; + return 0; +} + +// { dg-final { scan-tree-dump-times " if " 1 "evrp" } } -- 2.38.1