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Subject: Re: g++ 3.4 and -fprofile-generate

Author: Frank Phillips

Date: 15:29:53 02/16/05

Go up one level in this thread


On February 16, 2005 at 16:26:50, Robert Hyatt wrote:

>On February 16, 2005 at 15:57:46, Andrew Williams wrote:
>
>>On February 16, 2005 at 15:33:24, Robert Hyatt wrote:
>>
>>>On February 16, 2005 at 14:28:57, Dieter Buerssner wrote:
>>>
>>>>On February 16, 2005 at 13:19:46, Robert Hyatt wrote:
>>>>
>>>>>On February 16, 2005 at 13:09:14, Frank Phillips wrote:
>>>>
>>>>>>I have been using the profile generated optimisation option, but the code it
>>>>>>produces is no faster then with simple -O3.
>>>>
>>>>I have no experience on AMD64. On x86 it works well for me, under Linux and
>>>>Windows.
>>>>
>>>>>ICC (Intel's compiler) works fine and that is what I use
>>>>>myself.
>>>>
>>>>Does profile guided optimizatation with ICC work for you, when you run crafty
>>>>under xboard. It doesn't work for me.
>>>
>>>Never tried.  I do my profile runs via a "Make profile" where I have a target
>>>that compiles for profiling, runs a bunch of test cases, then compiles using the
>>>data gathered to improve the code.  So my profiling is all in "command mode" as
>>>well, which is just as good since the xboard stuff is not in the search of my
>>>program at all anyway.
>>>
>>>
>>>> Console runs work fine. With gcc, I can
>>>>rund a match Yace-Crafty under Xboard. That gave better speedups than
>>>>test-suites. But no luck with ICC here. I get very modest speedups with PGO and
>>>>ICC (more with gcc). However, ICC is fast even without PGO.
>>>
>>>I can't get gcc to compile and run crafty with profiling optimizations.  It will
>>>produce the profile data files fine, but when I go to re-compile with the
>>>options to use the profile data, it complains about one or more of the profile
>>>data files being corrupted.  I've tested this hundreds of times since this was
>>>put into gcc, no luck at all.  I seem to recall I might have gotten it to work
>>>on the opteron last year, but I don't believe there was any speedup if I did,
>>>and I might well be remembering that wrong anyway.
>>>
>>>But gcc won't profile-optimize for me period. although it will profile just fine
>>>and produce output that helps in analyzing performance.
>>>
>>>
>>>
>>
>>I had this phenomenon and I got rid of it by removing an optimization option.
>>I'm afraid I don't remember which one, but I think it was -fomit_frame_pointer;
>>I discovered what the problem was while reading a website, which I can no longer
>>find.
>>
>>Andrew
>
>
>I think I did this.  It seems to me that -fomit-frame-pointer produces errors
>when used with any sort of profiling, but I am not sure...
>
>I'll try again to see...

Try just -fprofile-arcs / -fprofile-brach-probabilities instead of generate/use,
which if I seem to remember did not work in at least one version of gcc3.3
(Mandrake 10.0 IIRC).

Frank



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