From owner-svn-src-head@freebsd.org Wed Sep 25 01:39:59 2019 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 691B4F7B6A; Wed, 25 Sep 2019 01:39:59 +0000 (UTC) (envelope-from jhibbits@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46dLMz1kWmz4GBw; Wed, 25 Sep 2019 01:39:59 +0000 (UTC) (envelope-from jhibbits@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 1E7AF854C; Wed, 25 Sep 2019 01:39:59 +0000 (UTC) (envelope-from jhibbits@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x8P1dxiM098432; Wed, 25 Sep 2019 01:39:59 GMT (envelope-from jhibbits@FreeBSD.org) Received: (from jhibbits@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x8P1dw15098431; Wed, 25 Sep 2019 01:39:58 GMT (envelope-from jhibbits@FreeBSD.org) Message-Id: <201909250139.x8P1dw15098431@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: jhibbits set sender to jhibbits@FreeBSD.org using -f From: Justin Hibbits Date: Wed, 25 Sep 2019 01:39:58 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r352667 - head/sys/powerpc/include X-SVN-Group: head X-SVN-Commit-Author: jhibbits X-SVN-Commit-Paths: head/sys/powerpc/include X-SVN-Commit-Revision: 352667 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Sep 2019 01:39:59 -0000 Author: jhibbits Date: Wed Sep 25 01:39:58 2019 New Revision: 352667 URL: https://svnweb.freebsd.org/changeset/base/352667 Log: powerpc/atomic: Follow recommendations on atomic primitive comparisons Both IBM and Freescale programming examples presume the cmpset operands will favor equal, and pessimize the non-equal case instead. Do the same for atomic_cmpset_* and atomic_fcmpset_*. This slightly pessimizes the failure case, in favor of the success case. MFC after: 3 weeks Modified: head/sys/powerpc/include/atomic.h Modified: head/sys/powerpc/include/atomic.h ============================================================================== --- head/sys/powerpc/include/atomic.h Wed Sep 25 01:23:08 2019 (r352666) +++ head/sys/powerpc/include/atomic.h Wed Sep 25 01:39:58 2019 (r352667) @@ -568,7 +568,7 @@ atomic_cmpset_int(volatile u_int* p, u_int cmpval, u_i __asm __volatile ( "1:\tlwarx %0, 0, %2\n\t" /* load old value */ "cmplw %3, %0\n\t" /* compare */ - "bne 2f\n\t" /* exit if not equal */ + "bne- 2f\n\t" /* exit if not equal */ "stwcx. %4, 0, %2\n\t" /* attempt to store */ "bne- 1b\n\t" /* spin if failed */ "li %0, 1\n\t" /* success - retval = 1 */ @@ -592,12 +592,12 @@ atomic_cmpset_long(volatile u_long* p, u_long cmpval, #ifdef __powerpc64__ "1:\tldarx %0, 0, %2\n\t" /* load old value */ "cmpld %3, %0\n\t" /* compare */ - "bne 2f\n\t" /* exit if not equal */ + "bne- 2f\n\t" /* exit if not equal */ "stdcx. %4, 0, %2\n\t" /* attempt to store */ #else "1:\tlwarx %0, 0, %2\n\t" /* load old value */ "cmplw %3, %0\n\t" /* compare */ - "bne 2f\n\t" /* exit if not equal */ + "bne- 2f\n\t" /* exit if not equal */ "stwcx. %4, 0, %2\n\t" /* attempt to store */ #endif "bne- 1b\n\t" /* spin if failed */ @@ -684,7 +684,7 @@ atomic_fcmpset_int(volatile u_int *p, u_int *cmpval, u __asm __volatile ( "lwarx %0, 0, %3\n\t" /* load old value */ "cmplw %4, %0\n\t" /* compare */ - "bne 1f\n\t" /* exit if not equal */ + "bne- 1f\n\t" /* exit if not equal */ "stwcx. %5, 0, %3\n\t" /* attempt to store */ "bne- 1f\n\t" /* exit if failed */ "li %0, 1\n\t" /* success - retval = 1 */ @@ -709,12 +709,12 @@ atomic_fcmpset_long(volatile u_long *p, u_long *cmpval #ifdef __powerpc64__ "ldarx %0, 0, %3\n\t" /* load old value */ "cmpld %4, %0\n\t" /* compare */ - "bne 1f\n\t" /* exit if not equal */ + "bne- 1f\n\t" /* exit if not equal */ "stdcx. %5, 0, %3\n\t" /* attempt to store */ #else "lwarx %0, 0, %3\n\t" /* load old value */ "cmplw %4, %0\n\t" /* compare */ - "bne 1f\n\t" /* exit if not equal */ + "bne- 1f\n\t" /* exit if not equal */ "stwcx. %5, 0, %3\n\t" /* attempt to store */ #endif "bne- 1f\n\t" /* exit if failed */