What information does GCC Profile Guided Optimization (PGO) collect and which optimizations use it?

c++ gcc pgo lto
JohnTortugo picture JohnTortugo · Dec 14, 2012 · Viewed 24.2k times · Source

Which information does GCC collect when I enable -fprofile-generate and which optimization does in fact uses the collected information (when setting the -fprofile-use flag) ?

I need citations here. I've searched for a while but didn't found anything documented.

Information regarding link-time optimization (LTO) would be a plus! =D

Answer

chill picture chill · Dec 14, 2012

-fprofile-generate enables -fprofile-arcs, -fprofile-values and -fvpt.

-fprofile-use enables -fbranch-probabilities, -fvpt, -funroll-loops, -fpeel-loops and -ftracer

Source: http://gcc.gnu.org/onlinedocs/gcc-4.7.2/gcc/Optimize-Options.html#Optimize-Options

PS. Information about LTO also on that page.

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