re PR ipa/68035 (ipa performance issue when no procedures are present)

re PR ipa/68035 (ipa performance issue when no procedures are present)

Fix PR ipa/68035

	PR ipa/68035
	* ipa-icf.c (void sem_item::set_hash): New function.
	(sem_function::get_hash): Use renamed m_hash member variable.
	(sem_item::update_hash_by_addr_refs): Utilize get_hash.
	(sem_item::update_hash_by_local_refs): Likewise.
	(sem_variable::get_hash): Use renamed m_hash member variable.
	(sem_item_optimizer::update_hash_by_addr_refs): Utilize get_hash.
	(sem_item_optimizer::build_hash_based_classes): Utilize set_hash.
	(sem_item_optimizer::build_graph): As the hash value of an item
	is lazy initialized, force the calculation.
	* ipa-icf.h (set_hash): Declare new function and rename hash member
	variable to m_hash.
	* gcc.dg/ipa/pr68035.c: New test.

From-SVN: r230263