Harry Trinta <harrytpc@xxxxxxxxx> writes: > I have some question about "branch probabilities". I think I don't > quite understand how this works. > - What is the purpose of calculating the branch probabilities? The > propose is to use information about past executions (gcda files) to > optimize better the program that is compiling? Yes. > - Â"branch probabilities" is calculated by the compiler even when the > parameters Âprofile-arcs and ftest-coverage were not used? Yes, but in the absence of profiling information they are just informed guesses. > The source coverage.c Âhas a method coverage_init which is called by toplev.c. > The coverage_init calls the read_counts_file (in coverage.c), wich try > to open a file gcda. If this method find the file gcda, load the file > content in a hash (counts_hash) in memory ... Is that right? > If I'm right, what is the purpose of loading the information from a > GCDA in memory at compile time? This information is used by the > compiler only for branch probabilities? I think also for value profiling. Although it's possible that that data is stored somewhere else, I haven't looked. Ian
