From: Nathan Sidwell <nathan@acm.org>
To: "David Edelsohn" <dje.gcc@gmail.com>,
"Martin Liška" <mliska@suse.cz>,
"Jakub Jelinek" <jakub@redhat.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>, Jan Hubicka <jh@suse.cz>,
Andreas Schwab <schwab@suse.de>,
Richard Biener <richard.guenther@gmail.com>
Subject: Re: [PATCH] Detect whether target can use -fprofile-update=atomic
Date: Tue, 06 Sep 2016 12:15:00 -0000 [thread overview]
Message-ID: <c18da517-69c1-1e9c-da40-c97ff0e209a4@acm.org> (raw)
In-Reply-To: <CAGWvnymmbE9_xxBD1xWy+ZPJnr7f-iLfRMc4DHLhCshLJiH3rw@mail.gmail.com>
On 09/06/16 06:57, David Edelsohn wrote:
> What about Jakub's comment in the PR?
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77378#c6
This needs addressing. Can you clarify PPC behaviour, because I may have
misunderstood:
1) PPC currently has 64 bit counters -- but cannot support 64bit atomic ops in
32 bit mode.
2) PPC currently has 32 bit counters anyway.
I had interpreted the comment to be implying #2, but now I'm not so sure.
> The proposed patch seems wrong or at least incomplete. The recent
> change is imposing a 64 bit DImode counter when producing 32 bit code.
> PowerPC does support 64 bit atomic operations in 32 bit mode.
I'm presuming you've missed a 'NOT' in that sentence.
> Was there a design decision that profile counters always should be 64
> bits? Either 32 bit targets won't support multi-threaded profiling or
> 32 bit targets can overflow the counter sooner.
> Which is worse?
> Which is more likely?
My initial thought is that it is probably awkward to support 2 different sized
counter types in the 'same' config. I.e. 64-bit single-threaded counters and
32-bit threaded counters.
nathan
next prev parent reply other threads:[~2016-09-06 12:15 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 8:50 [PATCH 0/4] Various GCOV/PGO improvements marxin
2016-08-01 8:49 ` [PATCH 3/4] Fix typo in gcov.texi marxin
2016-08-01 8:50 ` [PATCH 4/4] Add tests for __gcov_dump and __gcov_reset marxin
2016-08-01 8:50 ` [PATCH 1/4] Cherry-pick fprofile-generate-atomic from google/gcc-4_9 branch marxin
2016-08-01 12:22 ` Nathan Sidwell
2016-08-01 13:29 ` Martin Liška
2016-08-04 14:48 ` Nathan Sidwell
2016-08-04 15:34 ` Martin Liška
2016-08-04 16:43 ` Nathan Sidwell
2016-08-04 17:03 ` Nathan Sidwell
2016-08-05 8:55 ` Martin Liška
2016-08-05 12:38 ` Nathan Sidwell
2016-08-05 12:48 ` Martin Liška
2016-08-05 13:14 ` Nathan Sidwell
2016-08-05 13:43 ` Martin Liška
2016-08-08 13:59 ` [PATCH 5/N] Add new *_atomic counter update function, (-fprofile-update=atomic) Martin Liška
2016-08-08 15:24 ` Nathan Sidwell
2016-08-08 16:51 ` Martin Liška
2016-08-08 17:03 ` Martin Liška
2016-08-09 12:36 ` Nathan Sidwell
2016-08-08 16:56 ` [PATCH] Fix POW2 histogram Martin Liška
2016-08-09 8:41 ` [PATCH 2/N] Fix usage of " Martin Liška
2016-08-09 12:37 ` Nathan Sidwell
2016-08-09 12:34 ` [PATCH] Fix " Nathan Sidwell
2016-08-09 11:24 ` [PATCH] Set -fprofile-update=atomic when -pthread is present Martin Liška
2016-08-09 12:40 ` Nathan Sidwell
2016-08-09 19:04 ` Andi Kleen
2016-08-12 13:31 ` Martin Liška
2016-08-18 3:16 ` Jeff Law
2016-08-18 11:02 ` Nathan Sidwell
2016-08-18 15:51 ` Andi Kleen
2016-08-18 15:53 ` Jeff Law
2016-10-03 12:13 ` Martin Liška
2016-10-03 12:26 ` Nathan Sidwell
2016-10-03 16:46 ` Jeff Law
2016-10-03 17:52 ` Andi Kleen
2016-10-04 12:05 ` Martin Liška
2016-10-05 17:54 ` Jeff Law
2016-10-13 15:34 ` [PATCH] Introduce -fprofile-update=maybe-atomic Martin Liška
2016-10-31 9:13 ` Martin Liška
2016-11-10 13:19 ` Martin Liška
2016-11-10 15:43 ` Nathan Sidwell
2016-11-10 15:55 ` David Edelsohn
2016-11-10 16:18 ` Nathan Sidwell
2016-11-10 15:58 ` Martin Liška
2016-11-10 16:17 ` David Edelsohn
2016-11-10 16:24 ` Martin Liška
2016-11-10 17:31 ` Nathan Sidwell
2016-11-11 10:48 ` Martin Liška
2016-11-11 15:11 ` Nathan Sidwell
2016-11-10 16:14 ` Nathan Sidwell
2016-11-10 16:16 ` David Edelsohn
2016-08-18 15:54 ` [PATCH] Set -fprofile-update=atomic when -pthread is present Jakub Jelinek
2016-08-18 16:06 ` Richard Biener
2016-09-07 11:41 ` Martin Liška
[not found] ` <CAFiYyc0UaSzXhZmyG9QRkHGT4JFowxBfE2yb-NvXE=hR1xafdA@mail.gmail.com>
2016-09-15 10:18 ` [RFC] Speed-up -fprofile-update=atomic Martin Liška
2016-10-04 9:45 ` Richard Biener
2016-10-12 13:53 ` Martin Liška
2016-10-13 9:43 ` Richard Biener
2016-10-17 11:47 ` Martin Liška
[not found] ` <CAFiYyc3eDT4g926PPZuktz5fEW=k-PibAcxhigx4GBcxoXNJFQ@mail.gmail.com>
2016-10-24 12:09 ` Martin Liška
[not found] ` <CAFiYyc1tSdTdqqkHcMp+dgE43+8tHL6kY8E07TCHoZBeUT-ggQ@mail.gmail.com>
2016-10-25 14:32 ` Martin Liška
2016-10-26 9:29 ` Richard Biener
2016-10-26 9:32 ` Richard Biener
2016-08-18 16:04 ` [PATCH] Set -fprofile-update=atomic when -pthread is present Richard Biener
2016-08-10 12:57 ` [PATCH 1/4] Cherry-pick fprofile-generate-atomic from google/gcc-4_9 branch Nathan Sidwell
2016-08-13 12:14 ` [BUILDROBOT] avr broken (was: [PATCH 1/4] Cherry-pick fprofile-generate-atomic from google/gcc-4_9 branch) Jan-Benedict Glaw
[not found] ` <4455937b-eba7-fe66-fe1a-3172567dd1e4@suse.cz>
2016-08-16 13:36 ` [BUILDROBOT] avr broken Nathan Sidwell
[not found] ` <617e8799-b7db-fefd-b3a3-842e9a7decfd@suse.cz>
2016-08-16 14:31 ` Nathan Sidwell
2016-08-16 17:05 ` Jan-Benedict Glaw
2016-08-16 18:26 ` Nathan Sidwell
2016-08-17 7:21 ` Denis Chertykov
2016-08-17 7:22 ` Martin Liška
2016-08-17 8:11 ` Jan-Benedict Glaw
2016-08-16 12:56 ` [PATCH] Detect whether target can use -fprofile-update=atomic Martin Liška
2016-08-16 14:31 ` Nathan Sidwell
2016-09-06 10:57 ` Martin Liška
2016-09-06 11:17 ` David Edelsohn
2016-09-06 12:15 ` Nathan Sidwell [this message]
2016-09-06 12:39 ` Jakub Jelinek
2016-09-06 12:43 ` David Edelsohn
2016-09-06 12:41 ` David Edelsohn
2016-09-06 12:51 ` Martin Liška
2016-09-06 13:13 ` Jakub Jelinek
2016-09-06 13:15 ` Martin Liška
2016-09-06 13:45 ` Jakub Jelinek
2016-09-06 13:50 ` Martin Liška
2016-09-06 14:06 ` Jakub Jelinek
2016-09-07 7:52 ` Christophe Lyon
2016-09-07 9:35 ` Martin Liška
2016-09-07 16:06 ` Christophe Lyon
2016-09-12 20:20 ` Jeff Law
2016-09-29 8:31 ` Rainer Orth
2016-08-01 8:50 ` [PATCH 2/4] Remove __gcov_indirect_call_profiler marxin
2016-08-01 12:11 ` [PATCH 0/4] Various GCOV/PGO improvements Nathan Sidwell
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=c18da517-69c1-1e9c-da40-c97ff0e209a4@acm.org \
--to=nathan@acm.org \
--cc=dje.gcc@gmail.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=jakub@redhat.com \
--cc=jh@suse.cz \
--cc=mliska@suse.cz \
--cc=richard.guenther@gmail.com \
--cc=schwab@suse.de \
/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).