ipa-reorder-for-locality - Introduce C++ template heuristics

ipa-reorder-for-locality - Introduce C++ template heuristics

This patch introduces a new heuristics for reordering functions, to be used
in the absense of profile information.  This approach uses C++ template
instantiation types to group functions together.  Entry functions are sorted
in the beginning, and callees are sorted as part of partition_callchain ().

Bootstrapped and tested on aarch64-none-linux-gnu.

Signed-off-by: Prachi Godbole <pgodbole@nvidia.com>
config/ChangeLog:

	* bootstrap-lto-locality-cpp-template.mk: New file.

gcc/ChangeLog:

	* flag-types.h (enum lto_locality_heuristics): New enum.
	* ipa-locality-cloning.cc (struct templ_info): New struct.
	(struct locality_info): Add templ_info field.
	(templ_hash_map): New hash_map.
	(callee_templ_cmp): Ditto.
	(static_profile_templ_cmp): Ditto.
	(sort_templ_hashes_cmp): Ditto.
	(order_templ_hashes): Ditto.
	(locality_dc_template_p): Ditto.
	(populate_templ_info): Ditto.
	(create_locality_info): Call populate_templ_info.
	(partition_callchain): Call callee_templ_cmp.
	(locality_determine_static_order): Populate and sort templ_hash_map.
	(locality_partition_and_clone): Handle lto_locality_heuristics.
	(lc_execute): Initialize templ_hash_map.
	* params.opt: New param.