[gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[waltdnes]

  I put it into CFLAGS/CCFLAGS years ago, and left it there.  During a
discussion on the Pale Moon forum about build options, the opinion seems
to be that "-fomit-frame-pointer" is now the default.  Is that correct?
I'd like to simplify my CFLAGS/CCFLAGS both in Gentoo and the Pale Moon
build process.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[Michael Cook]

On 07/11/2016 04:27 PM, waltdnes@waltdnes.org wrote:
>   I put it into CFLAGS/CCFLAGS years ago, and left it there.  During a
> discussion on the Pale Moon forum about build options, the opinion seems
> to be that "-fomit-frame-pointer" is now the default.  Is that correct?
> I'd like to simplify my CFLAGS/CCFLAGS both in Gentoo and the Pale Moon
> build process.
>
It depends on the CPU. Most modern (x86 at least) stuff most likely are.

Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[J. García]

El lun, 11-07-2016 a las 16:27 -0400, waltdnes@waltdnes.org escribió:
>   I put it into CFLAGS/CCFLAGS years ago, and left it there.  During
> a
> discussion on the Pale Moon forum about build options, the opinion
> seems
> to be that "-fomit-frame-pointer" is now the default.  Is that
> correct?
> I'd like to simplify my CFLAGS/CCFLAGS both in Gentoo and the Pale
> Moon
> build process.
> 
I think it is, at least here it is a default, you can find out by
running:
gcc -c -Q --help=optimizers

It gets activated with -O, and -O2 is the default in Gentoo, so it
should be.
From the gcc manual:
"-O also turns on -fomit-frame-pointer on machines where doing so does
not interfere with debugging."

Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[Volker Armin Hemmann]

Am 11.07.2016 um 22:51 schrieb J. García:
> El lun, 11-07-2016 a las 16:27 -0400, waltdnes@waltdnes.org escribió:
>>   I put it into CFLAGS/CCFLAGS years ago, and left it there.  During
>> a
>> discussion on the Pale Moon forum about build options, the opinion
>> seems
>> to be that "-fomit-frame-pointer" is now the default.  Is that
>> correct?
>> I'd like to simplify my CFLAGS/CCFLAGS both in Gentoo and the Pale
>> Moon
>> build process.
>>
> I think it is, at least here it is a default, you can find out by
> running:
> gcc -c -Q --help=optimizers
>
> It gets activated with -O, and -O2 is the default in Gentoo, so it
> should be.
> >From the gcc manual:
> "-O also turns on -fomit-frame-pointer on machines where doing so does
> not interfere with debugging."
>
>
so it is not turned on on x86. Not sure about amd64. IIRC it is default
on amd64, but I am not sure and too lazy to google. Just like the thread
starter.

Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[waltdnes]

On Tue, Jul 12, 2016 at 01:48:37AM +0200, Volker Armin Hemmann wrote

> so it is not turned on on x86. Not sure about amd64. IIRC it is default
> on amd64, but I am not sure and too lazy to google. Just like the thread
> starter.

  Actually, I did Google.  So did another particpant in the Pale Moon
forum.  We got different answers, and various other people chimed in.
That's why I posted here.  BTW, "gcc -O2 -Q --help=optimizers" returns

  -fomit-frame-pointer                  [disabled]

...in both my real 64-bit Gentoo install and my 32-bit VM Gentoo.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[J. García]

El lun, 11-07-2016 a las 20:47 -0400, waltdnes@waltdnes.org escribió:
> On Tue, Jul 12, 2016 at 01:48:37AM +0200, Volker Armin Hemmann wrote
> 
> > so it is not turned on on x86. Not sure about amd64. IIRC it is
> > default
> > on amd64, but I am not sure and too lazy to google. Just like the
> > thread
> > starter.
> 
>   Actually, I did Google.  So did another particpant in the Pale Moon
> forum.  We got different answers, and various other people chimed in.
> That's why I posted here.  BTW, "gcc -O2 -Q --help=optimizers"
> returns
> 
>   -fomit-frame-pointer                  [disabled]
> 
> ...in both my real 64-bit Gentoo install and my 32-bit VM Gentoo.
> 
I made a mistake, I didn't ran the 'gcc -Q .." command correctly, a
typo, so I didn't really checked just got the list of optimizers, but
checking again I also have it disabled by default:

$ gcc -c   -march=core2 -O2 -Q --help=optimizers  |\
		grep fomit-frame-pointer
  -fomit-frame-pointer        		[disabled]

[gentoo-user] Re: Is "-fomit-frame-pointer" a gcc default?

[Holger Hoffstätte]

On Mon, 11 Jul 2016 19:23:24 -0600, "J." García wrote:

> El lun, 11-07-2016 a las 20:47 -0400, waltdnes@waltdnes.org escribió:
>> On Tue, Jul 12, 2016 at 01:48:37AM +0200, Volker Armin Hemmann wrote
>> 
>> > so it is not turned on on x86. Not sure about amd64. IIRC it is
>> > default
>> > on amd64, but I am not sure and too lazy to google. Just like the
>> > thread
>> > starter.
>> 
>>   Actually, I did Google.  So did another particpant in the Pale Moon
>> forum.  We got different answers, and various other people chimed in.
>> That's why I posted here.  BTW, "gcc -O2 -Q --help=optimizers"
>> returns
>> 
>>   -fomit-frame-pointer                  [disabled]
>> 
>> ...in both my real 64-bit Gentoo install and my 32-bit VM Gentoo.
>> 
> I made a mistake, I didn't ran the 'gcc -Q .." command correctly, a
> typo, so I didn't really checked just got the list of optimizers, but
> checking again I also have it disabled by default:
> 
> $ gcc -c   -march=core2 -O2 -Q --help=optimizers  |\
> 		grep fomit-frame-pointer
>   -fomit-frame-pointer        		[disabled]

No, gcc is just lying. See this reddit comment thread for details:
https://www.reddit.com/r/Cprog/comments/2iv09b/frame_pointer_omission_fpo_optimization_and/

Running the 'gcc -v' snippet shows that -fomit-frame-pointer is indeed
enabled by default on amd64.

-h

Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[Fernando Rodriguez]

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Hash: SHA256

On 07/11/2016 04:51 PM, J. García wrote:
> El lun, 11-07-2016 a las 16:27 -0400, waltdnes@waltdnes.org escribió:
>>   I put it into CFLAGS/CCFLAGS years ago, and left it there.  During
>> a
>> discussion on the Pale Moon forum about build options, the opinion
>> seems
>> to be that "-fomit-frame-pointer" is now the default.  Is that
>> correct?
>> I'd like to simplify my CFLAGS/CCFLAGS both in Gentoo and the Pale
>> Moon
>> build process.
>>
> I think it is, at least here it is a default, you can find out by
> running:
> gcc -c -Q --help=optimizers
> 
> It gets activated with -O, and -O2 is the default in Gentoo, so it
> should be.

No. At least for me it is -O0. I tested by compiling a small program with different
options and diffing the binaries. You can get a definitive answer for any gcc option
defaults like that. As long as your test program is complex enough to use those features.
You can also diff the output of the -f and -fno flags and if they don't differ then
either the test program is not complex enough or the feature has not effect on your arch
or platform.

> From the gcc manual:
> "-O also turns on -fomit-frame-pointer on machines where doing so does
> not interfere with debugging."
> 

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Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[Andrew Savchenko]

[-- Attachment #1: Type: text/plain, Size: 1519 bytes --]

Hi,

On Mon, 11 Jul 2016 16:27:42 -0400 waltdnes@waltdnes.org wrote:
>   I put it into CFLAGS/CCFLAGS years ago, and left it there.  During a
> discussion on the Pale Moon forum about build options, the opinion seems
> to be that "-fomit-frame-pointer" is now the default.  Is that o?
> I'd like to simplify my CFLAGS/CCFLAGS both in Gentoo and the Pale Moon
> build process.

gcc-5.3.0 manual says:
  The default setting (when not optimizing for size) for 32-bit
  GNU/Linux x86 and 32-bit Darwin x86 targets is
  -fomit-frame-pointer. You can configure GCC with the
  --enable-frame-pointer configure option to change the default.

So it depends not only on the arch, but also on how gcc was
compiled. Strange, but here Gentoo x86 I have -fomit-frame-pointer
disabled by default, so either gcc manpage is wrong or Gentoo
disables frame pointer during gcc configuration (I can't confirm the
latter after digging into toolchain eclass).

This flag is yummy on amd64 and very important on x86, since x86
has only 8 "general purpose" CPU registers, 4 of which have special
use, so only 4 are available for general computations and 1 of them
is wasted on frame-pointer, not nice. The cost of extra register is
that profiling is no longer possible and debugging may be mangled a
bit.

Looks like -fpic disables -fomit-frame-pointer at least for some
pieces of the code: hand-written 4-registers assembly makes -fpic
fail in some cases on x86 (e.g. ffmpeg).

Best regards,
Andrew Savchenko

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Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[konsolebox]

On Tue, Jul 12, 2016 at 6:07 PM, Andrew Savchenko <bircoph@gentoo.org> wrote:
> Hi,
>
> On Mon, 11 Jul 2016 16:27:42 -0400 waltdnes@waltdnes.org wrote:
>>   I put it into CFLAGS/CCFLAGS years ago, and left it there.  During a
>> discussion on the Pale Moon forum about build options, the opinion seems
>> to be that "-fomit-frame-pointer" is now the default.  Is that o?
>> I'd like to simplify my CFLAGS/CCFLAGS both in Gentoo and the Pale Moon
>> build process.
>
> gcc-5.3.0 manual says:
>   The default setting (when not optimizing for size) for 32-bit
>   GNU/Linux x86 and 32-bit Darwin x86 targets is
>   -fomit-frame-pointer. You can configure GCC with the
>   --enable-frame-pointer configure option to change the default.

And this was first mentioned in 4.6.0's changelog, but I don't see
anything about x86_64.

-- 
konsolebox

Re: [gentoo-user] Is "-fomit-frame-pointer" a gcc default?

[R0b0t1]

Pale Moon is routinely behind Firefox on security fixes (actual fixes,
not wanking-in-a-corner fixes).

[gentoo-user] Re: Is "-fomit-frame-pointer" a gcc default?

[»Q«]

On Tue, 12 Jul 2016 12:14:57 -0500
R0b0t1 <r030t1@gmail.com> wrote:

> Pale Moon is routinely behind Firefox on security fixes (actual fixes,
> not wanking-in-a-corner fixes).

Is anyone other than the Pale Moon team itself trying to track its
vulnerabilities?  I could only find one CVE for it, from 2013.

Re: [gentoo-user] Re: Is "-fomit-frame-pointer" a gcc default?

[waltdnes]

On Tue, Jul 12, 2016 at 05:09:28PM -0500, »Q« wrote
> On Tue, 12 Jul 2016 12:14:57 -0500
> R0b0t1 <r030t1@gmail.com> wrote:
> 
> > Pale Moon is routinely behind Firefox on security fixes (actual fixes,
> > not wanking-in-a-corner fixes).
> 
> Is anyone other than the Pale Moon team itself trying to track its
> vulnerabilities?  I could only find one CVE for it, from 2013.

  See http://www.palemoon.org/releasenotes.shtml with several mentions
of CVEs and other security fixes.  Given the amount of Firefox code
still present "under the hood", many Firefox security fixes will also
apply to Pale Moon.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

[gentoo-user] Re: Is "-fomit-frame-pointer" a gcc default?

[»Q«]

On Wed, 13 Jul 2016 16:53:40 -0400
waltdnes@waltdnes.org wrote:

> On Tue, Jul 12, 2016 at 05:09:28PM -0500, »Q« wrote
> > On Tue, 12 Jul 2016 12:14:57 -0500
> > R0b0t1 <r030t1@gmail.com> wrote:
> >   
> > > Pale Moon is routinely behind Firefox on security fixes (actual
> > > fixes, not wanking-in-a-corner fixes).  
> > 
> > Is anyone other than the Pale Moon team itself trying to track its
> > vulnerabilities?  I could only find one CVE for it, from 2013.  
> 
>   See http://www.palemoon.org/releasenotes.shtml with several mentions
> of CVEs and other security fixes.  Given the amount of Firefox code
> still present "under the hood", many Firefox security fixes will also
> apply to Pale Moon.

Checking just a few, the Pale Moon team takes anywhere from a few weeks
to a few months to fix security vulnerabilities which have been
published and fixed by Mozilla.  And other Firefox CVEs aren't
listed by Pale Moon, so it's tough to tell whether or not Pale
Moon is/was affected.  Maybe their fork of Gecko has diverged too much
to easily port Mozilla's fixes, I dunno. But not to worry, they have a
FAQ.

  Is Pale Moon safe to use?

  Absolutely! Pale Moon is based on the Mozilla release source code
  that has a large community of developers and security-aware people,
  next to having seen over a decade of development by now. [...]

OTOH, when it suits him, Moonchild stresses how very different his
codebase is now from Mozilla's.  

AFAICS, no one but the Pale Moon team is tracking Pale Moon
vulnerabilities.  I dunno what to make of their claims that it's safe
to use.