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Re: basic-block and profile-based optimizing (was Re: New attribute "infrequent"?)
- To: Andreas Jaeger <aj at suse dot de>
- Subject: Re: basic-block and profile-based optimizing (was Re: New attribute "infrequent"?)
- From: David Edelsohn <dje at watson dot ibm dot com>
- Date: Fri, 31 Aug 2001 12:17:15 -0400
- cc: Scott A Crosby <crosby at qwes dot math dot cmu dot edu>, Jan Hubicka <jh at suse dot cz>, gcc at gcc dot gnu dot org, pfk at fuchs dot offl dot uni-jena dot de
>>>>> Andreas Jaeger writes:
Andreas> Profile driven optimizations won't help directly in the case of
Andreas> libraries where you can't profile. That's AFAIR why Jan suggested
Andreas> this attribute.
While one cannot profile and tune a system-wide library for each
application's use, one can profile and optimize the library with
representative *real* applications. Most library functions are used in
standard ways, so profile-directed feedback tuning of the system libraries
can be useful. The exceptional cases and error recovery paths are
consistent. One needs to accept that the library is optimized only once
for all potential applications, but that generic optimization can be
effective for the system.