Fix PR debug/41065

gcc/ChangeLog:
	PR debug/41065
	* function.h (types_used_by_vars_hash): Declare new hash table.
	(types_used_by_vars_eq, types_used_by_var_decl_insert): Declare
	equality and hash function for the hash table.
	(types_used_by_cur_var_decl): Declare a new global chained list.
	(types_used_by_var_decl_insert): Declare new function.
	* function.c (types_used_by_vars_hash): Define the hashtable ...
	(types_used_by_vars_eq, types_used_by_vars_do_hash): ... as well as
	its equality and hash functions.
	(hash_types_used_by_vars_entry): New hash helper.
	(types_used_by_cur_var_decl): Define the global chained list.
	(used_types_insert): Update the list of types used by the global
	variable being parsed.
	(types_used_by_var_decl_insert): Define new function.
	* c-common.h (record_types_used_by_current_var_decl): Declare ...
	* c-common.c (record_types_used_by_current_var_decl): ... new
	function.
	* c-decl.c (finish_decl): Record the types used by the global
	variable declaration we've just parsed.
	* dwarf2out.c (premark_used_types): Insert a new line between
	comment and function.
	(premark_used_types_helper): Fix comment.
	(premark_types_used_by_global_vars_helper,
	premark_types_used_by_global_vars): New functions.
	(prune_unused_types): Do not prune types used by global variables.

gcc/cp/ChangeLog:
	PR debug/41065
	* decl.c (cp_finish_decl): Record the types used by the global
	variable declaration we've just parsed.

gcc/testsuite/ChangeLog:
	PR debug/41065
	* gcc.dg/debug/dwarf2/global-used-types.c: New test.

From-SVN: r152085