PR lto/78211
	* ipa-icf.h (sem_item_optimizer): Add m_classes_vec member.
	* ipa-icf.c (sem_item_optimizer::sem_item_optimizer): Initialize
	it.
	(sem_item_optimizer::~sem_item_optimizer): Traverse m_classes_vec
	vector instead of traversing m_classes hash table.  Release
	m_classes_vec.
	(sem_item_optimizer::read_section, sem_item_optimizer::add_class):
	Formatting fixes.
	(sem_item_optimizer::get_group_by_hash): When inserting a new group,
	add it also to m_classes_vec vector.
	(sem_item_optimizer::remove_symtab_node,
	sem_item_optimizer::build_hash_based_classes,
	sem_item_optimizer::parse_nonsingleton_classes): Formatting fixes.
	(sem_item_optimizer::subdivide_classes_by_equality,
	sem_item_optimizer::subdivide_classes_by_sensitive_refs,
	sem_item_optimizer::verify_classes): Traverse m_classes_vec vector
	instead of traversing m_classes hash table.  Formatting fixes.
	(sem_item_optimizer::traverse_congruence_split,
	sem_item_optimizer::do_congruence_step_for_index,
	sem_item_optimizer::do_congruence_step): Formatting fixes.
	(sem_item_optimizer::process_cong_reduction): Traverse m_classes_vec
	vector instead of traversing m_classes hash table.
	(sem_item_optimizer::dump_cong_classes): Likewise.  Formatting fixes.
	(sem_item_optimizer::merge_classes): Traverse m_classes_vec vector
	instead of traversing m_classes hash table.

	* g++.dg/ipa/pr78211.C: New test.

From-SVN: r242910