From patchwork Mon Aug 8 08:07:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roger Sayle X-Patchwork-Id: 56594 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 826F8385737C for ; Mon, 8 Aug 2022 08:07:39 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from server.nextmovesoftware.com (server.nextmovesoftware.com [162.254.253.69]) by sourceware.org (Postfix) with ESMTPS id BE0213858287 for ; Mon, 8 Aug 2022 08:07:20 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org BE0213858287 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=nextmovesoftware.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=nextmovesoftware.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=nextmovesoftware.com; s=default; h=Content-Type:MIME-Version:Message-ID: Date:Subject:To:From:Sender:Reply-To:Cc:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=P0IUAOr51V1XS3n5I+uvppmTCbjFxQHmyDQKLmQqgg0=; b=pnmkKzJbOm9ulsgSckT6z7a3Wd eImjZZn/vtof8InKwqZTeZwGjcGIfr+xl3JOhWcEPCR/wUep2KkOcgsiw9ehviC+wkspT2hAM7MSS idOz8tqtykd3oxyP0vr63a8AsWnq8Oxt0kfBbjFU9JQ9c5vzo50cGgKrA9hBHChMKzpsqQ1j1894m DJbqaU9TZP81a5FOXiqWyZoaIu9ry6WYEQRDGZxTAEUGBov4RLI2FPEaCwtMmUlMs/UMF5ODFMcvB hhzQmQvN42qqge5dGyz8BjLjrYRDL7hWUGVSaBeTtkvDGsmfODlndI2AT97axiNLfKV3DcpWnMf74 DD60c0Iw==; Received: from host86-169-41-119.range86-169.btcentralplus.com ([86.169.41.119]:57016 helo=Dell) by server.nextmovesoftware.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oKxnD-0005MN-Lw for gcc-patches@gcc.gnu.org; Mon, 08 Aug 2022 04:07:19 -0400 From: "Roger Sayle" To: Subject: [PATCH] PR tree-optimization/71343: Optimize (X< MIME-Version: 1.0 X-Mailer: Microsoft Outlook 16.0 Thread-Index: Adiq/VoMU7jUXs6WSfS3cL8QJP0Pwg== Content-Language: en-gb X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - server.nextmovesoftware.com X-AntiAbuse: Original Domain - gcc.gnu.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - nextmovesoftware.com X-Get-Message-Sender-Via: server.nextmovesoftware.com: authenticated_id: roger@nextmovesoftware.com X-Authenticated-Sender: server.nextmovesoftware.com: roger@nextmovesoftware.com X-Source: X-Source-Args: X-Source-Dir: X-Spam-Status: No, score=-10.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_BARRACUDACENTRAL, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" This patch resolves PR tree-optimization/71343, a missed-optimization enhancement request where GCC fails to see that (a<<2)+(b<<2) == a*4+b*4. This requires two related (sets of) optimizations to be added to match.pd. The first is that (X< 4*X" will always evaluate to false. This patch has been tested on x86_64-pc-linux-gnu with make bootstrap and make -k check, both with and without --target_board=unix{-m32}, with no new failures. Ok for mainline? 2022-08-08 Roger Sayle gcc/ChangeLog PR tree-optimization/71343 * match.pd (op (lshift @0 @1) (lshift @2 @1)): Optimize the expression (X<>C)^(Y>>C) to (X^Y)>>C for binary logical operators, AND, IOR and XOR. (cmp:c (lshift @0) (mult @1)): Optimize comparisons between shifts by integer constants and multiplications by powers of 2. gcc/testsuite/ChangeLog PR tree-optimization/71343 * gcc.dg/pr71343-1.c: New test case. * gcc.dg/pr71343-2.c: Likewise. Thanks in advance, Roger diff --git a/gcc/match.pd b/gcc/match.pd index f82f94a..d6b9cfb 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -982,6 +982,35 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) && tree_nop_conversion_p (type, TREE_TYPE (@1))) (lshift @0 @2))) +/* Shifts by constants distribute over several binary operations, + hence (X << C) + (Y << C) can be simplified to (X + Y) << C. */ +(for op (plus minus) + (simplify + (op (lshift:s @0 INTEGER_CST@1) (lshift:s @2 INTEGER_CST@1)) + (if (INTEGRAL_TYPE_P (type) + && TYPE_OVERFLOW_WRAPS (type) + && !TYPE_SATURATING (type) + && tree_fits_shwi_p (@1) + && tree_to_shwi (@1) > 0 + && tree_to_shwi (@1) < TYPE_PRECISION (type)) + (lshift (op @0 @2) @1)))) + +(for op (bit_and bit_ior bit_xor) + (simplify + (op (lshift:s @0 INTEGER_CST@1) (lshift:s @2 INTEGER_CST@1)) + (if (INTEGRAL_TYPE_P (type) + && tree_fits_shwi_p (@1) + && tree_to_shwi (@1) > 0 + && tree_to_shwi (@1) < TYPE_PRECISION (type)) + (lshift (op @0 @2) @1))) + (simplify + (op (rshift:s @0 INTEGER_CST@1) (rshift:s @2 INTEGER_CST@1)) + (if (INTEGRAL_TYPE_P (type) + && tree_fits_shwi_p (@1) + && tree_to_shwi (@1) > 0 + && tree_to_shwi (@1) < TYPE_PRECISION (type)) + (rshift (op @0 @2) @1)))) + /* Fold (1 << (C - x)) where C = precision(type) - 1 into ((1 << C) >> x). */ (simplify @@ -2241,6 +2270,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (if (TREE_INT_CST_LOW (@1) & 1) { constant_boolean_node (cmp == NE_EXPR, type); }))) +/* Some tree expressions are intentionally non-canonical. + We handle the comparison of the equivalent forms here. */ +(for cmp (eq le ge) + (simplify + (cmp:c (lshift @0 INTEGER_CST@1) (mult @0 integer_pow2p@2)) + (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && tree_fits_shwi_p (@1) + && tree_to_shwi (@1) > 0 + && tree_to_shwi (@1) < TYPE_PRECISION (TREE_TYPE (@0)) + && wi::to_wide (@1) == wi::exact_log2 (wi::to_wide (@2))) + { constant_boolean_node (true, type); }))) + +(for cmp (ne lt gt) + (simplify + (cmp:c (lshift @0 INTEGER_CST@1) (mult @0 integer_pow2p@2)) + (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && tree_fits_shwi_p (@1) + && tree_to_shwi (@1) > 0 + && tree_to_shwi (@1) < TYPE_PRECISION (TREE_TYPE (@0)) + && wi::to_wide (@1) == wi::exact_log2 (wi::to_wide (@2))) + { constant_boolean_node (false, type); }))) + /* Arguments on which one can call get_nonzero_bits to get the bits possibly set. */ (match with_possible_nonzero_bits diff --git a/gcc/testsuite/gcc.dg/pr71343-1.c b/gcc/testsuite/gcc.dg/pr71343-1.c new file mode 100644 index 0000000..146f5fc --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr71343-1.c @@ -0,0 +1,56 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ + +unsigned int foo_plus(unsigned int a, unsigned int b) +{ + return (a << 2) + (b << 2); +} + +unsigned int foo_and(unsigned int a, unsigned int b) +{ + return (a << 2) & (b << 2); +} + +unsigned int foo_ior(unsigned int a, unsigned int b) +{ + return (a << 2) | (b << 2); +} + +unsigned int foo_xor(unsigned int a, unsigned int b) +{ + return (a << 2) ^ (b << 2); +} + +unsigned int bar_and(unsigned int a, unsigned int b) +{ + return (a >> 2) & (b >> 2); +} + +unsigned int bar_ior(unsigned int a, unsigned int b) +{ + return (a >> 2) | (b >> 2); +} + +unsigned int bar_xor(unsigned int a, unsigned int b) +{ + return (a >> 2) ^ (b >> 2); +} + +int baz_and(int a, int b) +{ + return (a >> 2) & (b >> 2); +} + +int baz_ior(int a, int b) +{ + return (a >> 2) | (b >> 2); +} + +int baz_xor(int a, int b) +{ + return (a >> 2) ^ (b >> 2); +} + +/* { dg-final { scan-tree-dump-times " << " 4 "optimized" } } */ +/* { dg-final { scan-tree-dump-times " >> " 6 "optimized" } } */ + diff --git a/gcc/testsuite/gcc.dg/pr71343-2.c b/gcc/testsuite/gcc.dg/pr71343-2.c new file mode 100644 index 0000000..11800a9 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr71343-2.c @@ -0,0 +1,34 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ + +unsigned int test1(unsigned int a , unsigned int b) +{ + return (a << 2) + (b << 2) == a * 4 + b * 4; +} + +unsigned int test2(unsigned int a , unsigned int b) +{ + return (a << 2) + (b << 2) == (a + b) << 2; +} + +unsigned int test3(unsigned int a , unsigned int b) +{ + return a * 4 + b * 4 == (a + b) * 4; +} + +unsigned int test4(unsigned int a , unsigned int b) +{ + return (a + b) << 2 == (a + b) * 4; +} + +unsigned int test5(unsigned int a , unsigned int b) +{ + return (a << 2) + (b << 2) == (a + b) * 4; +} + +unsigned int test6(unsigned int a , unsigned int b) +{ + return (a + b) << 2 == a * 4 + b * 4; +} + +/* { dg-final { scan-tree-dump-times "return 1" 6 "optimized" } } */