From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19908 invoked by alias); 3 Jan 2013 01:29:51 -0000 Received: (qmail 19899 invoked by uid 22791); 3 Jan 2013 01:29:50 -0000 X-SWARE-Spam-Status: No, hits=-5.2 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,KHOP_RCVD_TRUST,KHOP_THREADED,RCVD_IN_DNSWL_LOW,RCVD_IN_HOSTKARMA_YE,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mail-qa0-f48.google.com (HELO mail-qa0-f48.google.com) (209.85.216.48) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 03 Jan 2013 01:29:45 +0000 Received: by mail-qa0-f48.google.com with SMTP id l8so9404721qaq.0 for ; Wed, 02 Jan 2013 17:29:44 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:x-gm-message-state; bh=JcjwObaV3cFuizqVNatGjkHNxoH9BEvSCfb/Yh76raA=; b=MmtkFxHGww/SA9yVKGZO9/HC9DUgoHEGZxxbms438obSwFKz0waoRXzb3XtXvFJIMy OJy76cLMBH4RuhiFQmb+6hrvByKLzPV/JByNmfqUEgfv1EJbn4/xkXZ6/pUJr9vWCUM7 0pmjzOnTwoFSxR/tqdlx/e2BUdoVQGeMUZg4789YAODaCn2W7LM63ZGtxzPqgUM6pR0F QOeTxNm7f0C9Z6axWegIRtAP5SUItf5b+4jNBPuSp8bIZDThbrI0lZwW+Uo++O2/QCao RdKPU9CWgedcQN/hYEaLykocg7lJKPVsiiTui2Kgbfq78cXCY95HjHQ3XJ46pAmsqr44 e+sA== MIME-Version: 1.0 Received: by 10.49.61.102 with SMTP id o6mr30564529qer.41.1357176584168; Wed, 02 Jan 2013 17:29:44 -0800 (PST) Received: by 10.229.146.13 with HTTP; Wed, 2 Jan 2013 17:29:44 -0800 (PST) In-Reply-To: References: <20121221064539.0E1A7100704@rong.mtv.corp.google.com> <20121221092532.GA7055@kam.mff.cuni.cz> Date: Thu, 03 Jan 2013 01:29:00 -0000 Message-ID: Subject: Re: atomic update of profile counters (issue7000044) From: Rong Xu To: Andrew Pinski Cc: Xinliang David Li , Jan Hubicka , GCC Patches , reply@codereview.appspotmail.com Content-Type: text/plain; charset=ISO-8859-1 X-Gm-Message-State: ALoCoQkbraCP8XSe9cEzr3xHo4OVp4RV7QSSxF2aLopRnQvOtqpOMye7b7nPhS3kHUzPUxlQXNBQQ+gxDQ28GHm7Maj2yL46vfTw92vdJXe2pMPWrxQJw11lps8HyEyqDl8Wu2+aUm8VgjO88/75FcpXdYk9xd5sJ0vkcIq/j/c6eZHNbYebP26BI4Z+pu8zQnmff/aBTQ83 X-IsSubscribed: yes Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org X-SW-Source: 2013-01/txt/msg00074.txt.bz2 Does libatomic support all targets? I think it's a good idea to change the driver to link in this library if the option is specified. But still, we need to make the builtin weak. Thanks, -Rong On Wed, Jan 2, 2013 at 5:25 PM, Andrew Pinski wrote: > On Wed, Jan 2, 2013 at 5:15 PM, Rong Xu wrote: >> Hi, >> >> Here is a new patch. The only difference is to declare >> __atomic_fetch_add as weak. This is >> needed for targets without sync/atomic builtin support. The patch >> contains a call to the builtin regardless of the new options >> -fprofile-gen-atomic. This results in a unsat in these targets even >> for regular profile-gen built. >> >> With this new patch, if the user uses -fprofile-gen-atomic in these >> target, the generated code will seg fault. >> >> We think a better solution is to emit the builtin call only in these >> targets with the support, and give warning for non-supported target. >> But I did not find any target hook for this. Does anyone know how to >> do this? > > Why not use libatomic for those targets? > > Thanks, > Andrew Pinski > > > >> >> Thanks, >> >> -Rong >> >> >> On Fri, Dec 28, 2012 at 11:35 AM, Xinliang David Li wrote: >>> It would be great if this can make into gcc4.8. The patch has close to >>> 0 impact on code stability. >>> >>> David >>> >>> On Fri, Dec 28, 2012 at 11:32 AM, Rong Xu wrote: >>>> Hi Honza, >>>> >>>> In the other thread of discussion (similar patch in google-4_7 >>>> branch), you said you were thinking if to let this patch into trunk in >>>> stage 3. Can you give some update? >>>> >>>> Thanks, >>>> >>>> -Rong >>>> >>>> On Fri, Dec 21, 2012 at 10:37 AM, Rong Xu wrote: >>>>> On Fri, Dec 21, 2012 at 1:25 AM, Jan Hubicka wrote: >>>>>>> Hi, >>>>>>> >>>>>>> This patch adds support of atomic update of profiles counters. The goal is to improve >>>>>>> the poor counter values for highly thread programs. >>>>>>> >>>>>>> The atomic update is under a new option -fprofile-gen-atomic= >>>>>>> N=0: default, no atomic update >>>>>>> N=1: atomic update edge counters. >>>>>>> N=2: atomic update some of value profile counters (currently indirect-call and one value profile). >>>>>>> N=3: both edge counter and the above value profile counters. >>>>>>> Other value: fall back to the default. >>>>>>> >>>>>>> This patch is a simple porting of the version in google-4_7 branch. It uses __atomic_fetch_add >>>>>>> based on Andrew Pinski's suggestion. Note I did not apply to all the value profiles as >>>>>>> the indirect-call profile is the most relevant one here. >>>>>>> >>>>>>> Test with bootstrap. >>>>>>> >>>>>>> Comments and suggestions are welcomed. >>>>>>> >>>>>>> Thanks, >>>>>>> >>>>>>> -Rong >>>>>>> >>>>>>> >>>>>>> 2012-12-20 Rong Xu >>>>>>> >>>>>>> * libgcc/libgcov.c (__gcov_one_value_profiler_body_atomic): New >>>>>>> function. Atomic update profile counters. >>>>>>> (__gcov_one_value_profiler_atomic): Ditto. >>>>>>> (__gcov_indirect_call_profiler_atomic): Ditto. >>>>>>> * gcc/gcov-io.h: Macros for atomic update. >>>>>>> * gcc/common.opt: New option. >>>>>>> * gcc/tree-profile.c (gimple_init_edge_profiler): Atomic >>>>>>> update profile counters. >>>>>>> (gimple_gen_edge_profiler): Ditto. >>>>>> >>>>>> The patch looks resonable. Eventually we probably should provide rest of the value counters >>>>>> in thread safe manner. What happens on targets not having atomic operations? >>>>> >>>>> From http://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html#_005f_005fsync-Builtins, >>>>> it says: >>>>> "If a particular operation cannot be implemented on the target >>>>> processor, a warning is generated and a call an external function is >>>>> generated. " >>>>> >>>>> So I think there will be a warning and eventually a link error of unsat. >>>>> >>>>> Thanks, >>>>> >>>>> -Rong >>>>> >>>>> >>>>>> >>>>>> Honza