IPA ICF pass, part 3/5

IPA ICF pass, part 3/5

	* Makefile.in: New object files included.
	* cgraph.c (cgraph_node::dump): New cgraph_node flag icf_merged
	is printed.
	(verify_edge_corresponds_to_fndecl): More sensitive verification
	of nodes that are merged by IPA ICF.
	* cgraph.h (cgraph_node::num_references): New function.
	* cgraphunit.c (cgraph_node::expand_thunk): White space fixed.
	* common.opt: New options ipa-icf, ipa-icf-functions and
	ipa-icf-variables introduced.
	* doc/invoke.texi: Documentation of new options introduced.
	* ipa-icf-gimple.c: New file.
	* ipa-icf-gimple.h: New file.
	* ipa-icf.c: New file.
	* ipa-icf.h: New file.
	* lto-cgraph.c (lto_output_node): Streaming of icf_merged flag added.
	(input_overwrite_node): Likewise.
	* lto-section-in.c: New icf section added.
	* lto-streamer.h (enum lto_section_type): Likewise.
	* opts.c (common_handle_option): New option added.
	* passes.def: New pass included.
	* timevar.def: Time variable for IPA ICF added.
	* tree-pass.h: New IPA ICF pass entry point added.

Co-Authored-By: Jan Hubicka <hubicka@ucw.cz>
From-SVN: r216305