From: Segher Boessenkool <segher@kernel.crashing.org>
To: Richard Biener <rguenther@suse.de>
Cc: Roman Zhuykov <zhroma@ispras.ru>,
"Kewen.Lin" <linkw@linux.ibm.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
Bill Schmidt <wschmidt@linux.ibm.com>,
"bin.cheng" <bin.cheng@linux.alibaba.com>
Subject: Re: [PATCH 0/4 GCC11] IVOPTs consider step cost for different forms when unrolling
Date: Wed, 12 Feb 2020 10:02:00 -0000 [thread overview]
Message-ID: <20200212100155.GC22482@gate.crashing.org> (raw)
In-Reply-To: <nycvar.YFH.7.76.2002120907460.18835@zhemvz.fhfr.qr>
On Wed, Feb 12, 2020 at 09:12:58AM +0100, Richard Biener wrote:
> On Tue, 11 Feb 2020, Segher Boessenkool wrote:
> > Basic block partitioning has wildly disproportionate fallout in all
> > later passes, both in terms of what those *do* (or don't, if partitioning
> > is enabled), and of impact on the code (not to mention developer time).
> >
> > Maybe the implementation can be improved, but probably we should do this
> > in a different way altogether. The current situation is not good.
>
> I think the expectation that you can go back to CFG layout mode
> and then work with CFG layout tools after we've lowered to CFG RTL
> is simply bogus.
Partitioning is also quite problematic if you do not use cfglayout
mode. For example, in shrink-wrapping. It prevents a lot there.
> Yeah, you can probably do analysis things but
> I wouldn't be surprised if a CFG RTL -> CFG layout -> CFG RTL cycle
> can wreck things. Undoubtedly doing CFG manipulations is not going
> to work since CFG layout does not respect CFG RTL restrictions.
Doing CFG manipulations on CFG RTL mode directly is almost impossible
to do correctly.
For example, bb-reorder. Which is a much more important optimisation
than partitioning, btw.
> Partitioning simply uncovered latent bugs, there's nothing wrong
> with it IMHO.
I don't agree. The whole way EDGE_CROSSING works hinders all other
optimisations a lot.
Segher
next prev parent reply other threads:[~2020-02-12 10:02 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 9:41 Kewen.Lin
2020-01-16 9:43 ` [PATCH 1/4 GCC11] Add middle-end unroll factor estimation Kewen.Lin
2020-01-20 13:12 ` Segher Boessenkool
2020-02-10 6:20 ` [PATCH 1/4 v2 " Kewen.Lin
2020-02-10 23:34 ` Segher Boessenkool
2020-02-11 6:51 ` [PATCH 1/4 v3 " Kewen.Lin
2020-02-11 7:00 ` Segher Boessenkool
2020-02-11 2:15 ` [PATCH 1/4 v2 " Jiufu Guo
2020-02-11 3:04 ` Kewen.Lin
2020-01-16 10:02 ` [PATCH 2/4 GCC11] Add target hook stride_dform_valid_p Kewen.Lin
2020-01-20 10:53 ` Richard Sandiford
2020-01-20 11:47 ` Richard Biener
2020-01-20 13:20 ` Segher Boessenkool
2020-02-25 9:46 ` Kewen.Lin
2020-03-02 11:09 ` Richard Sandiford
2020-03-03 12:26 ` Kewen.Lin
2020-05-13 5:50 ` Kewen.Lin
2020-05-28 2:17 ` Ping^1 [PATCH 2/4 V3] " Kewen.Lin
2020-05-28 10:54 ` Richard Sandiford
2020-01-16 10:06 ` [PATCH 3/4 GCC11] IVOPTs Consider cost_step on different forms during unrolling Kewen.Lin
2020-02-25 9:48 ` [PATCH 3/4 V2 " Kewen.Lin
2020-05-13 5:42 ` [PATCH 3/4 V3 " Kewen.Lin
2020-01-16 10:12 ` [PATCH 4/4 GCC11] rs6000: P9 D-form test cases Kewen.Lin
2020-01-20 13:37 ` Segher Boessenkool
2020-02-10 6:25 ` [PATCH 4/4 v2 " Kewen.Lin
2020-02-10 23:51 ` Segher Boessenkool
2020-01-20 13:03 ` [PATCH 0/4 GCC11] IVOPTs consider step cost for different forms when unrolling Segher Boessenkool
2020-02-10 6:17 ` Kewen.Lin
2020-02-10 21:29 ` Segher Boessenkool
2020-02-11 2:56 ` Kewen.Lin
2020-02-11 7:34 ` Richard Biener
2020-02-11 7:49 ` Segher Boessenkool
2020-02-11 8:01 ` Richard Biener
2020-02-11 12:46 ` Roman Zhuykov
2020-02-11 13:58 ` Richard Biener
2020-02-11 18:00 ` Segher Boessenkool
2020-02-12 8:07 ` Richard Biener
2020-02-12 21:53 ` Segher Boessenkool
2020-02-11 18:12 ` Segher Boessenkool
2020-02-12 8:13 ` Richard Biener
2020-02-12 10:02 ` Segher Boessenkool [this message]
2020-02-12 10:53 ` Richard Biener
2020-02-12 22:05 ` Segher Boessenkool
2020-02-13 7:48 ` Richard Biener
2020-02-13 9:02 ` Segher Boessenkool
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=20200212100155.GC22482@gate.crashing.org \
--to=segher@kernel.crashing.org \
--cc=bin.cheng@linux.alibaba.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=linkw@linux.ibm.com \
--cc=rguenther@suse.de \
--cc=wschmidt@linux.ibm.com \
--cc=zhroma@ispras.ru \
/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).