Add TYPE_EMPTY_RECORD for C++ empty classhjl/pr60336/x86

Empty record should be returned and passed the same way in C and C++.
This patch overloads a bit, side_effects_flag, in tree_base for C++
empty class.  Middle-end and x86 backend are updated to ignore empty
records for parameter passing and function value return.  Other targets
may need similar changes.

get_ref_base_and_extent is changed to set bitsize to 0 for empty records
so that when ref_maybe_used_by_call_p_1 calls get_ref_base_and_extent to
get 0 as the maximum size on empty record.  Otherwise, find_tail_calls
won't perform tail call optimization for functions with empty record
parameters, as shown in g++.dg/pr60336-1.C and g++.dg/pr60336-2.C.

A new cxx target hook, function_skip_empty_class_p, is added, which
defaults to return false.  This ABI change is enabled only if the ABI
level is at least 10, which is updated in GCC 6, and the target hook
TARGET_CXX_FUNCTION_SKIP_EMPTY_CLASS_P returns true.

gcc/

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* calls.c (initialize_argument_information): Warn empty record
	if they are used in a variable argument list or aren't the last
	arguments.  Replace targetm.calls.function_arg,
	targetm.calls.function_incoming_arg and
	targetm.calls.function_arg_advance with function_arg,
	function_incoming_arg and function_arg_advance.
	(expand_call): Replace targetm.calls.function_arg,
	targetm.calls.function_incoming_arg and
	targetm.calls.function_arg_advance with function_arg,
	function_incoming_arg and function_arg_advance.
	(emit_library_call_value_1): Likewise.
	(store_one_arg): Use 0 for empty record size.  Don't
	push 0 size argument onto stack.
	(must_pass_in_stack_var_size_or_pad): Return false for empty
	record.
	* dse.c (get_call_args): Replace targetm.calls.function_arg
	and targetm.calls.function_arg_advance with function_arg and
	function_arg_advance.
	* explow.c (hard_function_value): Use 0 for empty record size.
	* expr.c (block_move_libcall_safe_for_call_parm): Replace
	targetm.calls.function_arg and targetm.calls.function_arg_advance
	with function_arg and function_arg_advance.
	(copy_blkmode_to_reg): Use 0 for empty record size.
	* function.c (aggregate_value_p): Replace
	targetm.calls.return_in_memory with return_in_memory.
	(assign_parm_data_all): Add warn_empty_record.
	(assign_parms_augmented_arg_list): Set warn_empty_record if
	empty records are used in a variable argument list or aren't
	the last arguments.
	(assign_parm_find_entry_rtl): Warn empty record if
	warn_empty_record is set.  Replace
	targetm.calls.function_incoming_arg with function_incoming_arg.
	(assign_parms): Only warn empty record once.  Replace
	targetm.calls.function_arg_advance with function_arg_advance.
	(gimplify_parameters): Replace targetm.calls.function_arg_advance
	with function_arg_advance.
	(locate_and_pad_parm): Use 0 for empty record size.
	(warn_empty_record): New function.
	(function_arg_advance): New wrapper function.
	(function_arg): Likewise.
	(function_incoming_arg): Likewise.
	(return_in_memory): Likewise.
	* lto-streamer-out.c (hash_tree): Call hstate.add_flag with
	TYPE_EMPTY_RECORD for types.
	* print-tree.c (print_node): Also handle TYPE_EMPTY_RECORD.
	* ubsan.c (ubsan_type_descriptor): Likewise.
	* target.def (cxx): Add function_skip_empty_class_p.
	* target.h (function_arg_advance): New prototype.
	(function_arg): Likewise.
	(function_incoming_arg): Likewise.
	(return_in_memory): Likewise.
	* targhooks.c (std_gimplify_va_arg_expr): Use 0 for empty record
	size.
	* tree-dfa.c (get_ref_base_and_extent): Likewise.
	* tree-core.h (tree_base): Mention TYPE_EMPTY_RECORD in comments
	for side_effects_flag.
	* tree-streamer-in.c (unpack_ts_base_value_fields): Stream in
	TYPE_EMPTY_RECORD for types.
	* tree-streamer-out.c (pack_ts_base_value_fields): Stream out
	TYPE_EMPTY_RECORD for types.
	* tree.h (TYPE_EMPTY_RECORD): New.
	(type_is_empty_record_p): New static inline function.
	* var-tracking.c (prepare_call_arguments): Replace
	targetm.calls.function_arg and targetm.calls.function_arg_advance
	with function_arg and function_arg_advance.
	* config/i386/i386.c (ix86_gimplify_va_arg): Use 0 for empty
	record size.
	(TARGET_CXX_FUNCTION_SKIP_EMPTY_CLASS_P): New hook to return true.
	* doc/tm.texi.in (TARGET_CXX_FUNCTION_SKIP_EMPTY_CLASS_P): New
	hook.
	* doc/tm.texi: Regenerated.

gcc/c

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* c-aux-info.c (gen_type): Add TYPE_EMPTY_RECORD check.

gcc/cp/

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* class.c (is_empty_collection): New function.
	(is_empty_record): Likewise.
	(finish_struct_1): Set TYPE_EMPTY_RECORD with return value from
	is_empty_record () if the ABI level is at least 10.

gcc/lto/

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* lto.c (compare_tree_sccs_1): Call compare_values with
	TYPE_EMPTY_RECORD for types.

gcc/testsuite/

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* g++.dg/abi/empty12.C: New test.
	* g++.dg/abi/empty12.h: Likewise.
	* g++.dg/abi/empty12a.c: Likewise.
	* g++.dg/abi/empty13.C: Likewise.
	* g++.dg/abi/empty13.h: Likewise.
	* g++.dg/abi/empty13a.c: Likewise.
	* g++.dg/abi/empty14.C: Likewise.
	* g++.dg/abi/empty14.h: Likewise.
	* g++.dg/abi/empty14a.c: Likewise.
	* g++.dg/abi/empty15.C: Likewise.
	* g++.dg/abi/empty15.h: Likewise.
	* g++.dg/abi/empty15a.c: Likewise.
	* g++.dg/abi/empty16.C: Likewise.
	* g++.dg/abi/empty16.h: Likewise.
	* g++.dg/abi/empty16a.c: Likewise.
	* g++.dg/abi/empty17.C: Likewise.
	* g++.dg/abi/empty17.h: Likewise.
	* g++.dg/abi/empty17a.c: Likewise.
	* g++.dg/pr60336-1.C: Likewise.
	* g++.dg/pr60336-2.C: Likewise.
	* g++.dg/pr60336-3.C: Likewise.
	* g++.dg/pr60336-4.C: Likewise.
	* g++.dg/pr60336-5.C: Likewise.
	* g++.dg/pr60336-6.C: Likewise.
	* g++.dg/pr60336-7.C: Likewise.
	* g++.dg/pr60336-8.C: Likewise.
	* g++.dg/pr60336-9.C: Likewise.
	* g++.dg/pr60336-10.C: Likewise.
	* g++.dg/pr60336-11.C: Likewise.
	* g++.dg/pr60336-12.C: Likewise.
	* g++.dg/pr68355.C: Likewise.

0 files changed, 0 insertions, 0 deletions