# Re: Compiling Ruby w/ Profile Guided Optimization

**URL:** <https://www.ruby-forum.com/t/re-compiling-ruby-w-profile-guided-optimization/94818>\
**Category:** Ruby\
**Created:** [May 15, 2006, 6:23pm UTC](https://www.ruby-forum.com/t/re-compiling-ruby-w-profile-guided-optimization/94818 "2006-05-15T18:23:44Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![BergerS\_Daniel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/bc8723/32.png) [@BergerS\_Daniel](https://www.ruby-forum.com/u/BergerS_Daniel)\
**Post date:** [May 15, 2006, 6:23pm UTC](https://www.ruby-forum.com/t/re-compiling-ruby-w-profile-guided-optimization/94818/1 "2006-05-15T18:23:44Z")

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> Ruby with this feature turned on. For the (somewhat  
> contrived/synthetic) scenario below, it looks like compiling  
> with profile guided optimization turned on, along with -O3,  
> results in about a 9% speed increase vs. -O3 alone.  
> YMMV. I compiled a version of Ruby-1.8.4 using the  
> following config options…
> 
> ```
> configure CFLAGS="-O3 -fprofile-generate" 
> 
> ```
> 
> LDFLAGS=-fprofile-generate

Odd, I thought Ruby died a horrible death if compiled with -O3. Has  
that changed with gcc 4.x?

Thanks,

Dan

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<div class="post-metadata">

**Author:** ![BergerS\_Daniel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/bc8723/32.png) [@BergerS\_Daniel](https://www.ruby-forum.com/u/BergerS_Daniel)\
**Post date:** [May 15, 2006, 9:03pm UTC](https://www.ruby-forum.com/t/re-compiling-ruby-w-profile-guided-optimization/94818/2 "2006-05-15T21:03:46Z")

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On May 15, 2006, at 9:20 AM, Berger, Daniel wrote:

> > YMMV. I compiled a version of Ruby-1.8.4 using the  
> > following config options…
> > 
> > ```
> > configure CFLAGS="-O3 -fprofile-generate"
> > 
> > ```
> > 
> > LDFLAGS=-fprofile-generate
> 
> Odd, I thought Ruby died a horrible death if compiled with -O3. Has  
> that changed with gcc 4.x?

On OS X Ruby can fail when compiled with -fschedule-insns2 which is  
in -O2.

–  
Eric H. - removed\_email\_address@domain.invalid - [http://blog.segment7.net](http://blog.segment7.net)  
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