Auto-FDO/FDO profile comparator

Auto-FDO/FDO profile comparator

the patch I sent from airport only worked if you produced the gcda files with
unpatched compiler.  For some reason auto-profile reading is interwinded into
gcov reading which is not necessary.  Here is cleaner version which also
makes the format bit more convenient.  One can now grep as:

grep "bb.*fdo.*very hot.*cold" *.profile | sort -n -k 5 -r | less

digits_2/30 bb 307 fdo 10273284651 (very hot) afdo 0 (auto FDO) (cold)  scaled 0 diff -10273284651, -100.00%
digits_2/30 bb 201 fdo 2295561442 (very hot) afdo 19074 (auto FDO) (cold)  scaled 1341585 diff -2294219857, -99.94%
digits_2/30 bb 203 fdo 1236123372 (very hot) afdo 9537 (auto FDO) (cold)  scaled 670792 diff -1235452580, -99.95%
digits_2/30 bb 200 fdo 1236123372 (very hot) afdo 9537 (auto FDO) (cold)  scaled 670792 diff -1235452580, -99.95%
digits_2/30 bb 202 fdo 1059438070 (very hot) afdo 9537 (auto FDO) (cold)  scaled 670792 diff -1058767278, -99.94%
new_solver/9 bb 246 fdo 413879041 (very hot) afdo 76594 (guessed) (cold)  scaled 5387299 diff -408491742, -98.70%
new_solver/9 bb 167 fdo 413792205 (very hot) afdo 76594 (guessed) (cold)  scaled 5387299 diff -408404906, -98.70%
new_solver/9 bb 159 fdo 387809230 (very hot) afdo 57182 (guessed) (cold)  scaled 4021940 diff -383787290, -98.96%
new_solver/9 bb 158 fdo 387809230 (very hot) afdo 60510 (guessed) (cold)  scaled 4256018 diff -383553212, -98.90%
new_solver/9 bb 138 fdo 387809230 (very hot) afdo 40917 (guessed) (cold)  scaled 2877929 diff -384931301, -99.26%
new_solver/9 bb 137 fdo 387809230 (very hot) afdo 43298 (guessed) (cold)  scaled 3045398 diff -384763832, -99.21%

This dumps basic blocks that do have large counts by normal profile feedback
but autofdo gives them small count (so they get cold).  These seems to be
indeed mostly basic blocks controlling loops.

gcc/ChangeLog:

	* auto-profile.cc (afdo_hot_bb_threshod): New global
	variable.
	(maybe_hot_afdo_count_p): New function.
	(autofdo_source_profile::read): Do not set up dump file;
	set afdo_hot_bb_threshod.
	(afdo_annotate_cfg): Handle partial training.
	(afdo_callsite_hot_enough_for_early_inline):
	Use maybe_hot_afdo_count_p.
	(auto_profile_offline::execute): Read autofdo file.
	* auto-profile.h (maybe_hot_afdo_count_p): Declare.
	(afdo_hot_bb_threshold): Declare.
	* coverage.cc (read_counts_file): Also set gcov_profile_info.
	(coverage_init): Do not read autofdo file.
	* opts.cc (enable_fdo_optimizations): Add autofdo parameter;
	do not set flag_branch_probabilities and flag_profile_values
	with it.
	(common_handle_option): Update.
	* passes.cc (finish_optimization_passes): Do not end branch
	prob here.
	(pass_manager::dump_profile_report): Also mark change after
	autofdo pass.
	* profile.cc: Include auto-profile.h
	(gcov_profile_info): New global variable.
	(struct afdo_fdo_record): New struture.
	(compute_branch_probabilities): Record afdo profile.
	(end_branch_prob): Dump afdo/fdo profile comparsion.
	* profile.h (gcov_profile_info): Declarre.
	* tree-profile.cc (tree_profiling): Call end_branch_prob
	(pass_ipa_tree_profile::gate): Also enable with autoFDO