* Revisit patch for Bug#11935?
@ 2016-12-05 0:07 Ravi Desai
2016-12-05 2:21 ` Paul Eggert
0 siblings, 1 reply; 9+ messages in thread
From: Ravi Desai @ 2016-12-05 0:07 UTC (permalink / raw)
To: emacs-devel
Hello all,
Lines 294-297 of src/lisp.h on master refer to Bug#11935, which
discusses including changes submitted for that bug-report once Debian
stable has a GCC >= 4.8
https://packages.debian.org/stable/devel/ says GCC is at 4.9.2-2.
Is this now a good time to revisit the original patch submitted for
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=11935 ?
Thanks
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 0:07 Revisit patch for Bug#11935? Ravi Desai
@ 2016-12-05 2:21 ` Paul Eggert
2016-12-05 8:12 ` Colin Baxter
` (2 more replies)
0 siblings, 3 replies; 9+ messages in thread
From: Paul Eggert @ 2016-12-05 2:21 UTC (permalink / raw)
To: Ravi Desai, emacs-devel
[-- Attachment #1: Type: text/plain, Size: 371 bytes --]
On 12/04/2016 04:07 PM, Ravi Desai wrote:
> Is this now a good time to revisit the original patch submitted for
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=11935 ?
I would guess not. As I recall, Eli is still using GCC 3, and I suspect
some other developers are still using pre-4.8 GCC. Let's kick this can
down the road a while more. I installed the attached.
[-- Attachment #2: 0001-src-lisp.h-Update-comment-to-kick-Og-down-the-road.patch --]
[-- Type: text/x-patch, Size: 909 bytes --]
From 02055b6de9df82a68d24ee38e7d19e93191938c2 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 4 Dec 2016 18:19:01 -0800
Subject: [PATCH] * src/lisp.h: Update comment to kick -Og down the road.
---
src/lisp.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/src/lisp.h b/src/lisp.h
index 94f1152..7dd9145 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -292,9 +292,8 @@ error !;
used elsewhere.
FIXME: Remove the lisp_h_OP macros, and define just the inline OP
- functions, once most developers have access to GCC 4.8 or later and
- can use "gcc -Og" to debug. Maybe in the year 2016. See
- Bug#11935.
+ functions, once "gcc -Og" (new to GCC 4.8) works well enough for
+ Emacs developers. Maybe in the year 2020. See Bug#11935.
Commentary for these macros can be found near their corresponding
functions, below. */
--
2.7.4
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 2:21 ` Paul Eggert
@ 2016-12-05 8:12 ` Colin Baxter
2016-12-05 13:57 ` Ravi Desai
2016-12-05 15:47 ` Eli Zaretskii
2 siblings, 0 replies; 9+ messages in thread
From: Colin Baxter @ 2016-12-05 8:12 UTC (permalink / raw)
To: Paul Eggert; +Cc: Ravi Desai, emacs-devel
On Sun, Dec 04 2016, Paul Eggert wrote:
> On 12/04/2016 04:07 PM, Ravi Desai wrote:
>> Is this now a good time to revisit the original patch submitted for
>> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=11935 ?
>
> I would guess not. As I recall, Eli is still using GCC 3, and I
> suspect some other developers are still using pre-4.8 GCC. Let's kick
> this can down the road a while more. I installed the attached.
For what it's worth, Debian is only on gcc 4.9 for Jessie. Wheezy has
4.7 or 4.6.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 2:21 ` Paul Eggert
2016-12-05 8:12 ` Colin Baxter
@ 2016-12-05 13:57 ` Ravi Desai
2016-12-05 15:47 ` Eli Zaretskii
2 siblings, 0 replies; 9+ messages in thread
From: Ravi Desai @ 2016-12-05 13:57 UTC (permalink / raw)
To: Paul Eggert; +Cc: emacs-devel
On 2016-12-04 09:21 PM, Paul Eggert wrote:
> On 12/04/2016 04:07 PM, Ravi Desai wrote:
>> Is this now a good time to revisit the original patch submitted for
>> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=11935 ?
>
> I would guess not. As I recall, Eli is still using GCC 3, and I
> suspect some other developers are still using pre-4.8 GCC. Let's kick
> this can down the road a while more. I installed the attached.
>
Sounds good. Thanks for the update.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 2:21 ` Paul Eggert
2016-12-05 8:12 ` Colin Baxter
2016-12-05 13:57 ` Ravi Desai
@ 2016-12-05 15:47 ` Eli Zaretskii
2016-12-05 16:26 ` martin rudalics
2016-12-05 17:08 ` Paul Eggert
2 siblings, 2 replies; 9+ messages in thread
From: Eli Zaretskii @ 2016-12-05 15:47 UTC (permalink / raw)
To: Paul Eggert; +Cc: ravi, emacs-devel
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sun, 4 Dec 2016 18:21:31 -0800
>
> On 12/04/2016 04:07 PM, Ravi Desai wrote:
> > Is this now a good time to revisit the original patch submitted for
> > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=11935 ?
>
> I would guess not. As I recall, Eli is still using GCC 3
No, those days are long gone. 5.3.0 is what I have here now.
> and I suspect some other developers are still using pre-4.8
> GCC. Let's kick this can down the road a while more. I installed the
> attached.
Thanks.
I think this is related not only to the GCC version, but also to
whether developers use -Og when building development versions of
Emacs. I'm still using -O0, and only switch to -Og when I build
pretests (and switch to -O2 when building the released tarballs).
That's because I've found that -Og still makes debugging more
difficult compared to -O0. For example, many values appear as
"optimized out" in the backtraces, which sometimes requires me to go
up the stack very far to find the value. (-Og is actually -O1 with a
couple of more aggressive optimizations disabled, so what I see is not
surprising.)
So the question is how many people who customary debug on the C level
build with -O0, regardless of their compiler version. Could people
who read this please tell what they use?
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 15:47 ` Eli Zaretskii
@ 2016-12-05 16:26 ` martin rudalics
2016-12-05 17:08 ` Paul Eggert
1 sibling, 0 replies; 9+ messages in thread
From: martin rudalics @ 2016-12-05 16:26 UTC (permalink / raw)
To: Eli Zaretskii, Paul Eggert; +Cc: ravi, emacs-devel
> So the question is how many people who customary debug on the C level
> build with -O0, regardless of their compiler version. Could people
> who read this please tell what they use?
On GNU/Linux I have an -O0 version for every toolkit which means more
than 20 (GTK, Lucid, Motif, no-toolkit, no-X, Cairo, GNUStep, GTK with
Lucid scroll bars times three for release, master, and master with my
modifications) builds. Add three -O0 builds on Windows. None of all
these builds can be used for editing purposes, so I also have three -O3
builds - two for GTK and one on Windows for doing normal work.
martin
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 15:47 ` Eli Zaretskii
2016-12-05 16:26 ` martin rudalics
@ 2016-12-05 17:08 ` Paul Eggert
2016-12-05 17:44 ` Stefan Monnier
1 sibling, 1 reply; 9+ messages in thread
From: Paul Eggert @ 2016-12-05 17:08 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: ravi, emacs-devel
On 12/05/2016 07:47 AM, Eli Zaretskii wrote:
> -Og still makes debugging more
> difficult compared to -O0. For example, many values appear as
> "optimized out" in the backtraces, which sometimes requires me to go
> up the stack very far to find the value.
If those "optimized out"s are an obstacle we should report them to the
GCC developers. I debugged Emacs with -Og, found an instance of
"optimized out", turned it into a small test case, and filed a bug
report with the GCC developers here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78685
Please feel free to add to it, or to report more bugs in this area.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 17:08 ` Paul Eggert
@ 2016-12-05 17:44 ` Stefan Monnier
2016-12-05 18:46 ` Eli Zaretskii
0 siblings, 1 reply; 9+ messages in thread
From: Stefan Monnier @ 2016-12-05 17:44 UTC (permalink / raw)
To: emacs-devel
> If those "optimized out"s are an obstacle we should report them to the GCC
> developers.
Really? Last I tried -Og they were so pervasive that it seemed very
clearly like a conscious decision on the part of the GCC maintainers.
Stefan "using -O0 with most/all checks enabled, all the time"
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Revisit patch for Bug#11935?
2016-12-05 17:44 ` Stefan Monnier
@ 2016-12-05 18:46 ` Eli Zaretskii
0 siblings, 0 replies; 9+ messages in thread
From: Eli Zaretskii @ 2016-12-05 18:46 UTC (permalink / raw)
To: Stefan Monnier; +Cc: emacs-devel
> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Mon, 05 Dec 2016 12:44:23 -0500
>
> > If those "optimized out"s are an obstacle we should report them to the GCC
> > developers.
>
> Really? Last I tried -Og they were so pervasive that it seemed very
> clearly like a conscious decision on the part of the GCC maintainers.
Same here. Let's see how the GCC developers respond to Paul's bug
report.
> Stefan "using -O0 with most/all checks enabled, all the time"
Right.
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2016-12-05 18:46 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
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2016-12-05 0:07 Revisit patch for Bug#11935? Ravi Desai
2016-12-05 2:21 ` Paul Eggert
2016-12-05 8:12 ` Colin Baxter
2016-12-05 13:57 ` Ravi Desai
2016-12-05 15:47 ` Eli Zaretskii
2016-12-05 16:26 ` martin rudalics
2016-12-05 17:08 ` Paul Eggert
2016-12-05 17:44 ` Stefan Monnier
2016-12-05 18:46 ` Eli Zaretskii
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