From patchwork Tue Nov 1 15:57:45 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Henderson X-Patchwork-Id: 123087 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 BF480B6F64 for ; Wed, 2 Nov 2011 02:58:12 +1100 (EST) Received: (qmail 32653 invoked by alias); 1 Nov 2011 15:58:05 -0000 Received: (qmail 32627 invoked by uid 22791); 1 Nov 2011 15:58:03 -0000 X-SWARE-Spam-Status: No, hits=-2.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM, RCVD_IN_DNSWL_LOW X-Spam-Check-By: sourceware.org Received: from mail-vw0-f47.google.com (HELO mail-vw0-f47.google.com) (209.85.212.47) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 01 Nov 2011 15:57:48 +0000 Received: by vwe42 with SMTP id 42so323490vwe.20 for ; Tue, 01 Nov 2011 08:57:47 -0700 (PDT) Received: by 10.52.240.145 with SMTP id wa17mr9294393vdc.118.1320163067748; Tue, 01 Nov 2011 08:57:47 -0700 (PDT) Received: from anchor.twiddle.net (c-98-203-235-125.hsd1.wa.comcast.net. [98.203.235.125]) by mx.google.com with ESMTPS id l1sm15115033vdi.0.2011.11.01.08.57.46 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 01 Nov 2011 08:57:47 -0700 (PDT) Message-ID: <4EB016F9.90200@gmail.com> Date: Tue, 01 Nov 2011 08:57:45 -0700 From: Richard Henderson User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0) Gecko/20110927 Thunderbird/7.0 MIME-Version: 1.0 To: GCC Patches , amacleod@redhat.com Subject: [RFC][cxx-mem-model] mem_signal_fence 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 Any comments on the expectation, or implementation of signal-fence below? Should I make the distinction between the memory models here at all? At minimum there's another typo in the ifdef section; we really need to minimize those... r~ diff --git a/gcc/builtins.c b/gcc/builtins.c index 756070f..34922a8 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -5530,16 +5530,18 @@ expand_builtin_atomic_is_lock_free (tree exp) /* This routine will either emit the mem_thread_fence pattern or issue a sync_synchronize to generate a fence for memory model MEMMODEL. */ +#ifndef HAVE_mem_thread_fence +# define HAVE_mem_thread_fence 0 +# define gen_mem_thread_fence(x) (gcc_unreachable (), NULL_RTX) +#endif + void expand_builtin_mem_thread_fence (enum memmodel model) { - if (model == MEMMODEL_RELAXED) - return; -#ifdef HAVE_mem_thread_fence - emit_insn (gen_mem_thread_fence (GEN_INT (model))); -#else - expand_builtin_sync_synchronize (); -#endif + if (HAVE_mem_thread_fence) + emit_insn (gen_mem_thread_fence (GEN_INT (model))); + else if (model != MEMMODEL_RELAXED) + expand_builtin_sync_synchronize (); } /* Expand the __atomic_thread_fence intrinsic: @@ -5558,15 +5560,38 @@ expand_builtin_atomic_thread_fence (tree exp) /* This routine will either emit the mem_signal_fence pattern or issue a sync_synchronize to generate a fence for memory model MEMMODEL. */ +#ifndef HAVE_mem_signal_fence +# define HAVE_mem_signal_fence 0 +# define gen_mem_signal_fence(x) (gcc_unreachable (), NULL_RTX) +#endif + static void expand_builtin_mem_signal_fence (enum memmodel model) { -#ifdef HAVE_mem_signal_fence - emit_insn (gen_mem_signal_fence (memmodel)); -#else - if (model != MEMMODEL_RELAXED) - expand_builtin_sync_synchronize (); -#endif + if (HAVE_mem_signal_fence) + emit_insn (gen_mem_signal_fence (GEN_INT (model))); + else + { + rtx x; + + /* By default I expect that targets are coherent between a thread and + the signal handler running on the same thread. Thus this really + becomes a compiler barrier, in that stores must not be sunk past + (or raised above) a given point. */ + switch (model) + { + case MEMMODEL_RELAXED: + break; + case MEMMODEL_SEQ_CST: + gen_blockage (); + break; + default: + x = gen_rtx_SCRATCH (Pmode); + x = gen_rtx_MEM (BLKmode, x); + emit_insn (gen_rtx_USE (x)); + break; + } + } } /* Expand the __atomic_signal_fence intrinsic: