-fomit-frame-pointer - Is this needed? [SOLVED]

DislexiK · Last edited by DislexiK on Mon Oct 18, 2004 1:12 pm; edited 1 time in total

I am currently bootstrapping, I have configured my CFLAGS in make.conf to the following:

CFLAGS="-march=athlon-xp -pipe -O3"

Now I have been browsing the Internet and all the time I see: -fomit-frame-pointer added as an option, should I have added this myself, I read what it does and understand it to be a pointer which helps increase compiling speed, however it can actually make debugging a lot harder, but then I read somewhere that it can be needed by debugging software?

Should I have added it, after bootstrapping would it cause any problems me adding it now if I need it, or should I do the bootstrap again, if I have to do the bootstrap again can I just initiate the bootstrap script again or should I format and start the process all over again...?

DislexiK
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DislexiK · Posted: Mon Oct 18, 2004 12:31 pm Post subject:

Ok please delete this thread, I have just read that -O3 actually turns on -fomit-frame-pointer where ever it needs to be used upon compiling.

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Maedhros · Posted: Mon Oct 18, 2004 12:50 pm Post subject:

For the future, you can remove your own posts as long as no-one's replied to them...

Edit: In fact, if you remove yours, then I can remove mine, and we can pretend the whole thing never happened! :lol:

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barry · Apprentice Joined: 01 May 2002 Posts: 170 Location: UK

-fomit-frame-pointer is never enabled using an -O option on the x86 (or AMD64) platform - assuming you're using one of those.

DislexiK · Posted: Wed Oct 20, 2004 6:22 am Post subject:

I have -march=athlon-xp

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barry · Apprentice Joined: 01 May 2002 Posts: 170 Location: UK

DislexiK · Posted: Wed Oct 20, 2004 3:34 pm Post subject:

Ok, few questions:

What does it do

If I add it now, will it screw anything up regarding compilations?

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barry · Apprentice Joined: 01 May 2002 Posts: 170 Location: UK

It improves the speed of the code but it's not suitable if you want to debug the programs (which sounds unlikely). It hardly ever causes a problem, and on those packages it's automatically filtered from your CFLAGS anyway.

DislexiK · Posted: Wed Oct 20, 2004 8:01 pm Post subject:

Ok, do you mean it improves the speed of the code of the application or the compilation speed?

If I start adding it now, will it affect anything I have already done?

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CaT · n00b Joined: 18 Oct 2004 Posts: 30

hi if you enable -fomit-frame-pointer then the frame pointers of functions, that will not be used. will not be kept in the register.

barry · Apprentice Joined: 01 May 2002 Posts: 170 Location: UK

It speeds up the execution of the produced code. Have a look in GCC's info page on optimisation - it's all detailed in there.