[Open64-devel] IPA and Profiling Feedback

[Christophe L. <chr...@st...>]

Hi all,

I am studying the differences between pro64-0.13 and ORC-2.1 concerning 
IPA and profiling feedback.

I have read the examples given on http://ipf-orc.sourceforge.net/ORC-faq.htm

but when I read the sources in ipa/common/ipc_compile.cxx, I can see 
that IPA always desactivate CG:enable_feedback, so I don't understand 
how the whole process works?

The example given in the link above basically instructs to do:
1.  "-O3 -ipa -fb_create fb.mid -fb_type=1 -fb_phase=0 "
2.  "-O3 -ipa -fb_opt fb.mid -fb_create fb.mid -fb_type=10 -fb_phase=4"
3.  "-O3 -ipa -fb_opt fb.mid"

So, if -ipa disables CG_enable_feedback, how does the 3rd phase benefit 
from the previous one?


Thanks,

Christophe.