ipa-profile.c: Add toplevel comment.

ipa-profile.c: Add toplevel comment.

	* ipa-profile.c: Add toplevel comment.
	(ipa_propagate_frequency_1): Be more conservative when profile is read.
	(contains_hot_call_p): New function.
	(ipa_propagate_frequency): Set frequencies based on counts when
	profile is read.
	* predict.c (compute_function_frequency): Use PROFILE_READ gueard for
	profile; do not tamper with profile after inlining if it is read.

From-SVN: r202382