From patchwork Fri Apr 22 15:21:57 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chung-Lin Tang X-Patchwork-Id: 92545 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) by ozlabs.org (Postfix) with SMTP id 085F01007DC for ; Sat, 23 Apr 2011 01:22:17 +1000 (EST) Received: (qmail 29479 invoked by alias); 22 Apr 2011 15:22:16 -0000 Received: (qmail 29470 invoked by uid 22791); 22 Apr 2011 15:22:15 -0000 X-SWARE-Spam-Status: No, hits=-1.8 required=5.0 tests=AWL, BAYES_00, T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mail.codesourcery.com (HELO mail.codesourcery.com) (38.113.113.100) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 22 Apr 2011 15:22:01 +0000 Received: (qmail 30441 invoked from network); 22 Apr 2011 15:22:00 -0000 Received: from unknown (HELO ?192.168.1.13?) (cltang@127.0.0.2) by mail.codesourcery.com with ESMTPA; 22 Apr 2011 15:22:00 -0000 Message-ID: <4DB19D15.9020509@codesourcery.com> Date: Fri, 22 Apr 2011 23:21:57 +0800 From: Chung-Lin Tang User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 MIME-Version: 1.0 To: gcc-patches CC: Richard Earnshaw Subject: [PATCH] Canonicalize compares in combine [3/3] ARM backend part X-IsSubscribed: yes Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org Hi Richard, this part's for you. The ARM backend changes needed are very little after the prior patches, basically just a case in arm_canonicalize_comparison() to detect (zero_extend:SI (subreg:QI (reg:SI ...) 0)), and swap it into (and:SI (reg:SI) #255). Had we not tried the combine modifications, this testcase probably could have also be solved by implementing another version of the corresponding *andsi3_compare0/_scratch patterns, with ZERO_EXTEND in the body, and "ands" in the output assembly. Maybe that's an acceptable solution too... About the (ab)use of CANONICALIZE_COMPARISON, if it really should be another macro/hook, then this ARM patch will need updating, but the code should be similar. Thanks, Chung-Lin Index: config/arm/arm.c =================================================================== --- config/arm/arm.c (revision 172860) +++ config/arm/arm.c (working copy) @@ -3276,6 +3276,19 @@ return code; } + /* If *op0 is (zero_extend:SI (subreg:QI (reg:SI) 0)) and comparing + with const0_rtx, change it to (and:SI (reg:SI) (const_int 255)), + to facilitate possible combining with a cmp into 'ands'. */ + if (mode == SImode + && GET_CODE (*op0) == ZERO_EXTEND + && GET_CODE (XEXP (*op0, 0)) == SUBREG + && GET_MODE (XEXP (*op0, 0)) == QImode + && GET_MODE (SUBREG_REG (XEXP (*op0, 0))) == SImode + && SUBREG_BYTE (XEXP (*op0, 0)) == 0 + && *op1 == const0_rtx) + *op0 = gen_rtx_AND (SImode, SUBREG_REG (XEXP (*op0, 0)), + GEN_INT (255)); + /* Comparisons smaller than DImode. Only adjust comparisons against an out-of-range constant. */ if (GET_CODE (*op1) != CONST_INT Index: testsuite/gcc.target/arm/combine-movs.c =================================================================== --- testsuite/gcc.target/arm/combine-movs.c (revision 0) +++ testsuite/gcc.target/arm/combine-movs.c (revision 0) @@ -0,0 +1,10 @@ +/* { dg-options "-O" } */ + +void foo (unsigned long r[], unsigned int d) +{ + int i, n = d / 32; + for (i = 0; i < n; ++i) + r[i] = 0; +} + +/* { dg-final { scan-assembler "movs\tr\[0-9\]" } } */ Index: testsuite/gcc.target/arm/unsigned-extend-2.c =================================================================== --- testsuite/gcc.target/arm/unsigned-extend-2.c (revision 0) +++ testsuite/gcc.target/arm/unsigned-extend-2.c (revision 0) @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O -march=armv6" } */ + +unsigned short foo (unsigned short x) +{ + unsigned char i = 0; + for (i = 0; i < 8; i++) + { + x >>= 1; + x &= 0x7fff; + } + return x; +} + +/* { dg-final { scan-assembler "ands" } } */ +/* { dg-final { scan-assembler-not "uxtb" } } */ +/* { dg-final { scan-assembler-not "cmp" } } */