From: Eric Hodel <drbrain@...7.net>
Date: 2006-05-16T04:02:09+09:00
Subject: Re: Compiling Ruby w/ Profile Guided Optimization

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

>> -----Original Message-----
>> From: Greg Buchholz [mailto:sleepingsquirrel@yahoo.com]
>> Subject: Compiling Ruby w/ Profile Guided Optimization
>>
>>     Since gcc-4.1 now has the option to perform profile
>> guided optimization, I thought I'd try compiling a version of
>> 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
>
> <snip>
>
> 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 Hodel - drbrain@segment7.net - http://blog.segment7.net
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