From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4465 invoked by alias); 1 Oct 2014 13:21:21 -0000 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 Received: (qmail 4453 invoked by uid 89); 1 Oct 2014 13:21:20 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.2 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-qc0-f173.google.com Received: from mail-qc0-f173.google.com (HELO mail-qc0-f173.google.com) (209.85.216.173) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Wed, 01 Oct 2014 13:21:18 +0000 Received: by mail-qc0-f173.google.com with SMTP id x13so260319qcv.18 for ; Wed, 01 Oct 2014 06:21:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=qe4R7eQ0u1DQNwzvV7nBCYwDH5BoD7BCVvxlhgY73nI=; b=XRKuXgGeVNI0jVAcbQrb8Sztgu8ibG7XLR8R4B3PXtKFZuHJNrCb4AO3xB/uJlWWhq MzlFE8AnpkZ2HijMNXylCmzEVyQoyp3AvUlutozDRIMX9HfInfm33DoCnbmPFisbndQ6 MCmVTKV1xIWpKXDGztNokm6w0HVaCjnIRM4AnnQwyHHmGRcRP8/Mki7Wewa/6q/T+s2K tSMjZF6lPhMp+DvnyaVEPbMePAqu/ROa+oRIdWDQXajjnq/yWn6ny+pAlZlXvRIANncD NaqsU4lS5Jf4bPy+Dv2mUTuoTcUJ5ADnCXRp/PgAjDtRJipi9uqnJWgKuvMqmWtXjCxW OYWQ== X-Gm-Message-State: ALoCoQn/JEtJhrXpUGIO7P7PvQt03pEX51nVT8Z3aP0uRoKbo/OcoQdAx4ibhSXT9v/eZ5al1Gf4 MIME-Version: 1.0 X-Received: by 10.140.92.199 with SMTP id b65mr37894579qge.86.1412169634348; Wed, 01 Oct 2014 06:20:34 -0700 (PDT) Received: by 10.229.148.1 with HTTP; Wed, 1 Oct 2014 06:20:34 -0700 (PDT) In-Reply-To: References: <53CF1DFD.7080805@redhat.com> <542A32AB.1040708@redhat.com> Date: Wed, 01 Oct 2014 13:21:00 -0000 Message-ID: Subject: Re: [PATCH] Redesign jump threading profile updates From: Teresa Johnson To: Christophe Lyon Cc: Jeff Law , "gcc-patches@gcc.gnu.org" , Jan Hubicka , David Li Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2014-10/txt/msg00050.txt.bz2 Sorry, yes, will try to reproduce. Teresa On Wed, Oct 1, 2014 at 12:03 AM, Christophe Lyon wrote: > On 30 September 2014 20:20, Teresa Johnson wrote: >> On Mon, Sep 29, 2014 at 9:33 PM, Jeff Law wrote: >>> On 09/29/14 08:19, Teresa Johnson wrote: >>>>> >>>>> >>>>> Just an update - I found some good test cases by compiling the >>>>> c-torture tests with profile feedback with and without my patch. But >>>>> in the cases I pulled out I saw that there were still a couple profile >>>>> or probability insanities introduced by jump threading (albeit far >>>>> less than before), so I wanted to investigate before I commit. I ran >>>>> out of time this week and will not get to this until I get back from >>>>> vacation the week after next. >>>> >>>> >>>> Hi Jeff, >>>> >>>> I finally had a chance to get back to this and look at the remaining >>>> insanities in the new test cases I created. It turns out that there >>>> were still a few issues in the case where there were guessed >>>> frequencies and no profile counts. The two test cases I created do use >>>> FDO, and the insanities in the routines with profile counts went away >>>> with my patch. But the outlined copies of routines that were also >>>> inlined into the main routine still had estimated frequencies, and >>>> these still had a few issues. >>>> >>>> The problem is that the profile updates are done incrementally as we >>>> walk and update the paths in ssa_fix_duplicate_block_edges, including >>>> the block and edge counts, the block frequencies and the >>>> probabilities. This is very difficult to do when only operating on >>>> frequencies since the edge frequencies are derived from the source >>>> block frequency and the probability. Therefore, once the source block >>>> frequency is updated, the edge frequency is also affected, and it is >>>> really difficult to figure out what the update to the edge frequency >>>> (essentially the probability) is using the same incremental update >>>> approach. I was attempting to handle this with the routine >>>> deduce_freq, for example, but this turned out to have issues for >>>> certain types of paths. I tried a few other approaches, but they start >>>> looking really ugly and I didn't want to add a parallel but different >>>> algorithm in the case of no profile counts. >>>> >>>> So by far the simplest approach was simply to take a snapshot of the >>>> existing block and edge frequencies along the path before we start the >>>> updates in ssa_fix_duplicate_block_edges, by copying them into the >>>> profile count fields of those blocks and edges. Then the existing >>>> algorithm operates the same as when we do have counts, and can >>>> essentially operate incrementally on the edge frequencies since they >>>> live in the count field of the edge and are no longer affected anytime >>>> the source block is updated. Since the algorithm does update block >>>> frequencies and probabilities as well (based on the count updates >>>> performed), we can simply clear out these fake count fields at the end >>>> of ssa_fix_duplicate_block_edges. This takes care of the remaining >>>> insanities introduced by jump threading from these test cases. During >>>> testing I also added in some checking to ensure that the count fields >>>> for the whole routine were cleared properly to make sure the new >>>> clear_counts_path was not missing anything (checking is a little too >>>> heavyweight to add in normally). >>>> >>>> New patch below (also attached since my mailer sometimes eats spaces). >>>> The differences between the old patch and the new one: >>>> - removed deduce_freq (which was my least favorite part of the patch >>>> anyway!), and its call from recompute_probabilities, since it is no >>>> longer necessary. >>>> - two new routines freqs_to_counts_path and clear_counts_path, invoked >>>> from ssa_fix_duplicate_block_edges. >>>> - two new tests >>>> >>>> Bootstrapped and tested on x86_64-unknown-linux-gnu, ok for trunk? >>>> >>>> Thanks, >>>> Teresa >>>> >>>> gcc: >>>> >>>> 2014-09-29 Teresa Johnson >>>> >>>> * tree-ssa-threadupdate.c (struct ssa_local_info_t): New >>>> duplicate_blocks bitmap. >>>> (remove_ctrl_stmt_and_useless_edges): Ditto. >>>> (create_block_for_threading): Ditto. >>>> (compute_path_counts): New function. >>>> (update_profile): Ditto. >>>> (recompute_probabilities): Ditto. >>>> (update_joiner_offpath_counts): Ditto. >>>> (freqs_to_counts_path): Ditto. >>>> (clear_counts_path): Ditto. >>>> (ssa_fix_duplicate_block_edges): Update profile info. >>>> (ssa_create_duplicates): Pass new parameter. >>>> (ssa_redirect_edges): Remove old profile update. >>>> (thread_block_1): New duplicate_blocks bitmap, >>>> remove old profile update. >>>> (thread_single_edge): Pass new parameter. >>>> >>>> gcc/testsuite: >>>> >>>> 2014-09-29 Teresa Johnson >>>> >>>> * testsuite/gcc.dg/tree-prof/20050826-2.c: New test. >>>> * testsuite/gcc.dg/tree-prof/cmpsf-1.c: Ditto. >>> >>> Given I'd already been through this pretty thoroughly, I just gave this a >>> cursory review. >>> >>> clear_counts_path needs a function comment. It's pretty obvious what it's >>> doing, but for completeness let's go ahead and get the obvious comment in >>> there. >> >> Done and committed as r215739. >> > > Since this commit, I can see all my builds for arm*linux* and > aarch64*linux* fail while building glibc: > > /tmp/3496222_18.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/tools/bin/aarch64-none-linux-gnu-gcc > iso-2022-cn.c -c -std=gnu99 -fgnu89-inline -O2 -Wall -Win > line -Wundef -Wwrite-strings -fmerge-all-constants -frounding-math -g > -Wstrict-prototypes -fPIC -I../include > -I/tmp/3496222_18.tmpdir/aci-gcc-f > sf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/glibc-1/iconvdata > -I/tmp/3496222_18.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux > -gnu/glibc-1 -I../sysdeps/unix/sysv/linux/aarch64/nptl > -I../sysdeps/unix/sysv/linux/aarch64 > -I../sysdeps/unix/sysv/linux/generic -I../sysdeps/unix/s > ysv/linux/wordsize-64 -I../nptl/sysdeps/unix/sysv/linux > -I../nptl/sysdeps/pthread -I../sysdeps/pthread > -I../sysdeps/unix/sysv/linux -I../sysdeps/gn > u -I../sysdeps/unix/inet -I../nptl/sysdeps/unix/sysv > -I../sysdeps/unix/sysv -I../nptl/sysdeps/unix -I../sysdeps/unix > -I../sysdeps/posix -I../sysd > eps/aarch64/fpu -I../sysdeps/aarch64/nptl -I../sysdeps/aarch64 > -I../sysdeps/wordsize-64 -I../sysdeps/ieee754/ldbl-128 > -I../sysdeps/ieee754/dbl-64/w > ordsize-64 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 > -I../sysdeps/aarch64/soft-fp -I../sysdeps/ieee754 > -I../sysdeps/generic -I../npt > l -I.. -I../libio -I. -nostdinc -isystem > /tmp/3496222_18.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/tools/lib/gcc/aarch64-none-linux-gnu/5.0.0/include > -i > system /tmp/3496222_18.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/tools/lib/gcc/aarch64-none-linux-gnu/5.0.0/include-fixed > -isystem /tmp/3496222_18.tmpdir > /aci-gcc-fsf/builds/gcc-fsf-gccsrc/sysroot-aarch64-none-linux-gnu/usr/include > -D_LIBC_REENTRANT -include ../include/libc-symbols.h -DPIC -DSHARED > -DNOT_IN_libc -o > /tmp/3496222_18.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/glibc-1/iconvdata/iso-2022-cn.os > -MD -MP -MF /tmp/3 > 496222_18.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/glibc-1/iconvdata/iso-2022-cn.os.dt > -MT /tmp/3496222_18.tmpdir/aci-gcc-fsf > /builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/glibc-1/iconvdata/iso-2022-cn.os > > In file included from iso-2022-cn.c:407:0: > ../iconv/skeleton.c: In function 'gconv': > ../iconv/skeleton.c:800:1: internal compiler error: in > check_probability, at basic-block.h:959 > 0xe4e2fb find_many_sub_basic_blocks(simple_bitmap_def*) > /tmp/3496222_18.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/basic-block.h:959 > 0x6623f0 execute > /tmp/3496222_18.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/cfgexpand.c:5916 > Please submit a full bug report, > with preprocessed source if appropriate. > Please include the complete backtrace with any bug report. > See for instructions. > > Can you have a look? > > Thanks, > > Christophe. > >> Thanks, >> Teresa >> >>> >>> With that fix, approved for the trunk. Thanks for taking the time to sort >>> out all these issues. >>> >>> jeff >>> >>> >> >> >> >> -- >> Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413 -- Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413