From owner-svn-src-head@freebsd.org Sun Sep 16 19:28:27 2018 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id CF79710A8789; Sun, 16 Sep 2018 19:28:27 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 83A417D620; Sun, 16 Sep 2018 19:28:27 +0000 (UTC) (envelope-from mjg@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 7E59826589; Sun, 16 Sep 2018 19:28:27 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w8GJSRZk022097; Sun, 16 Sep 2018 19:28:27 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w8GJSRxn022096; Sun, 16 Sep 2018 19:28:27 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <201809161928.w8GJSRxn022096@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Sun, 16 Sep 2018 19:28:27 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r338700 - head/sys/amd64/amd64 X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/amd64/amd64 X-SVN-Commit-Revision: 338700 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: 2.1.27 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: Sun, 16 Sep 2018 19:28:28 -0000 Author: mjg Date: Sun Sep 16 19:28:27 2018 New Revision: 338700 URL: https://svnweb.freebsd.org/changeset/base/338700 Log: amd64: tidy up kernel memmove There is no need to use %rax for temporary values and avoiding doing so shortens the func. Handle the explicit 'check for tail' depessimisization for backwards copying. This reduces the diff against userspace. Approved by: re (kib) Modified: head/sys/amd64/amd64/support.S Modified: head/sys/amd64/amd64/support.S ============================================================================== --- head/sys/amd64/amd64/support.S Sun Sep 16 18:36:42 2018 (r338699) +++ head/sys/amd64/amd64/support.S Sun Sep 16 19:28:27 2018 (r338700) @@ -108,12 +108,12 @@ END(sse2_pagezero) */ ENTRY(memmove_std) PUSH_FRAME_POINTER - movq %rdi,%r9 + movq %rdi,%rax movq %rdx,%rcx - movq %rdi,%rax - subq %rsi,%rax - cmpq %rcx,%rax /* overlapping && src < dst? */ + movq %rdi,%r8 + subq %rsi,%r8 + cmpq %rcx,%r8 /* overlapping && src < dst? */ jb 1f shrq $3,%rcx /* copy by 64-bit words */ @@ -128,7 +128,6 @@ ENTRY(memmove_std) 2: rep movsb - movq %r9,%rax POP_FRAME_POINTER ret @@ -140,8 +139,10 @@ ENTRY(memmove_std) decq %rsi andq $7,%rcx /* any fractional bytes? */ std + jne 3f rep movsb +3: movq %rdx,%rcx /* copy remainder by 32-bit words */ shrq $3,%rcx subq $7,%rsi @@ -149,24 +150,22 @@ ENTRY(memmove_std) rep movsq cld - movq %r9,%rax POP_FRAME_POINTER ret END(memmove_std) ENTRY(memmove_erms) PUSH_FRAME_POINTER - movq %rdi,%r9 + movq %rdi,%rax movq %rdx,%rcx - movq %rdi,%rax - subq %rsi,%rax - cmpq %rcx,%rax /* overlapping && src < dst? */ + movq %rdi,%r8 + subq %rsi,%r8 + cmpq %rcx,%r8 /* overlapping && src < dst? */ jb 1f rep movsb - movq %r9,%rax POP_FRAME_POINTER ret @@ -179,7 +178,6 @@ ENTRY(memmove_erms) rep movsb cld - movq %r9,%rax POP_FRAME_POINTER ret END(memmove_erms)