public inbox for gcc@gcc.gnu.org
 help / color / mirror / Atom feed
From: "Bin.Cheng" <amker.cheng@gmail.com>
To: Steve Ellcey <sellcey@marvell.com>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>, Jun Ma <majun4950646@gmail.com>
Subject: Re: GCC missing -flto optimizations? SPEC lbm benchmark
Date: Fri, 15 Feb 2019 09:12:00 -0000	[thread overview]
Message-ID: <CAHFci2_tSRtnA38KJjG+kWDDh387NGvY2owyUrmfZjS03def0Q@mail.gmail.com> (raw)
In-Reply-To: <92bfe075168981ee45e525875ac6a15f5e318034.camel@marvell.com>

On Fri, Feb 15, 2019 at 3:30 AM Steve Ellcey <sellcey@marvell.com> wrote:
>
> I have a question about SPEC CPU 2017 and what GCC can and cannot do
> with -flto.  As part of some SPEC analysis I am doing I found that with
> -Ofast, ICC and GCC were not that far apart (especially spec int rate,
> spec fp rate was a slightly larger difference).
>
> But when I added -ipo to the ICC command and -flto to the GCC command,
> the difference got larger.  In particular the 519.lbm_r was more than
> twice as fast with ICC and -ipo, but -flto did not help GCC at all.
>
> There are other tests that also show this type of improvement with -ipo
> like 538.imagick_r, 544.nab_r, 525.x264_r, 531.deepsjeng_r, and
> 548.exchange2_r, but none are as dramatic as 519.lbm_r.  Anyone have
> any idea on what ICC is doing that GCC is missing?  Is GCC just not
> agressive enough with its inlining?

IIRC Jun did some investigation before? CCing.

Thanks,
bin
>
> Steve Ellcey
> sellcey@marvell.com

  reply	other threads:[~2019-02-15  9:12 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-14 19:30 Steve Ellcey
2019-02-15  9:12 ` Bin.Cheng [this message]
2019-02-15  9:48   ` Jun Ma
2019-02-15 12:45     ` Hi-Angel
2019-02-15 13:12       ` Richard Biener
2019-02-15 13:15         ` Jakub Jelinek
2019-02-15 13:34           ` Ramana Radhakrishnan
2019-02-15 15:01       ` Ian Lance Taylor
2019-02-15 18:10         ` Joel Sherrill
2019-02-15 18:28           ` Richard Kenner
2019-02-15 20:52           ` Eric Botcazou
2019-02-15 17:53     ` [EXT] " Steve Ellcey
2019-02-16 14:36       ` Jun Ma

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAHFci2_tSRtnA38KJjG+kWDDh387NGvY2owyUrmfZjS03def0Q@mail.gmail.com \
    --to=amker.cheng@gmail.com \
    --cc=gcc@gcc.gnu.org \
    --cc=majun4950646@gmail.com \
    --cc=sellcey@marvell.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).