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thammaknot
Beginner
44 Views

-prof_gen and -fast

Hi,

Is there a problem with doing both ipo and profiling at the same time? because I tried to compile my c files using the command:

icc -fast -O3 -xKWN -prof_genx filename

and it gave me

icc: warning: PGOPTI instrumentation disables multifile optimizations

IPO: WARNING: no IR for object file /temp/iccBk6QDy.o; was the source file complied with -ipo?

Isn't there a way to include both?

thanks
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1 Reply
44 Views

Hi,
The profile generation stage and ipo do not mix. Now, the profile use (-prof_use) stage and ipo should work together to bring maximum performance to your application.
The fact that -prof_gen and -ipo do not mix should not be considered a major problem. To get accurate profile information, we need to tone down the optimization level so that when it comes to using the information, we can optimize in the correct places. Remember, you would not ship your production code compiled with -prof_gen. In this sense it's similar to using debug - Using -g or -Zi tones down some optimizations while you're developing. For shipping, you'd probably not use debug.
Max