re PR c++/60336 (empty struct value is passed differently in C and C++)

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* c-decl.c (grokdeclarator): Set DECL_PADDING_P on unnamed bit-fields.

	* class.c (layout_class_type): Set DECL_PADDING_P on padding.
	* decl.c (cxx_init_decl_processing): Set TRANSLATION_UNIT_WARN_EMPTY_P.
	(grokdeclarator): Set DECL_PADDING_P on unnamed bit-fields.

	* lto.c (compare_tree_sccs_1): Compare TYPE_EMPTY_P and DECL_PADDING_P.

	* calls.c (initialize_argument_information): Call
	warn_parameter_passing_abi target hook.
	(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 types.
	* common.opt: Update -fabi-version description.
	* config/i386/i386.c (init_cumulative_args): Set cum->warn_empty.
	(ix86_gimplify_va_arg): Call arg_int_size_in_bytes instead of
	int_size_in_bytes.
	(ix86_is_empty_record): New function.
	(ix86_warn_parameter_passing_abi): New function.
	(TARGET_EMPTY_RECORD_P): Redefine.
	(TARGET_WARN_PARAMETER_PASSING_ABI): Redefine.
	* config/i386/i386.h (CUMULATIVE_ARGS): Add warn_empty.
	* doc/tm.texi: Regenerated.
	* doc/tm.texi.in (TARGET_EMPTY_RECORD_P,
	TARGET_WARN_PARAMETER_PASSING_ABI): Add.
	* dwarf2out.c (get_ultimate_context): Move to tree.c.
	* explow.c (hard_function_value): Call arg_int_size_in_bytes
	instead of int_size_in_bytes.
	* expr.c (copy_blkmode_to_reg): Likewise.
	* function.c (aggregate_value_p): Return 0 for empty types.
	(assign_parm_find_entry_rtl): Call warn_parameter_passing_abi target hook.
	(locate_and_pad_parm): Call arg size_in_bytes instead
	size_in_bytes.
	* lto-streamer-out.c (hash_tree): Hash TYPE_EMPTY_P and DECL_PADDING_P.
	* stor-layout.c (finalize_type_size): Set TYPE_EMPTY_P.
	* target.def (empty_record_p, warn_parameter_passing_abi): New target
	hooks.
	* targhooks.c (hook_void_CUMULATIVE_ARGS_tree): New hook.
	(std_gimplify_va_arg_expr): Skip empty records.  Call
	arg_size_in_bytes instead size_in_bytes.
	* targhooks.h (hook_void_CUMULATIVE_ARGS_tree): Declare.
	* tree-core.h (tree_type_common): Add empty_flag.
	(tree_decl_common): Update comments.
	* tree-streamer-in.c (unpack_ts_decl_common_value_fields): Stream
	DECL_PADDING_P.
	(unpack_ts_type_common_value_fields): Stream TYPE_EMPTY_P.
	* tree-streamer-out.c (pack_ts_decl_common_value_fields): Stream
	DECL_PADDING_P.
	(pack_ts_type_common_value_fields): Stream TYPE_EMPTY_P.
	* tree.c (default_is_empty_type): New function.
	(default_is_empty_record): New function.
	(arg_int_size_in_bytes): New function.
	(arg_size_in_bytes): New function.
	(get_ultimate_context): New function.
	* tree.h: Define TYPE_EMPTY_P, DECL_PADDING_P and
	TRANSLATION_UNIT_WARN_EMPTY_P.
	(default_is_empty_record, arg_int_size_in_bytes,
	arg_size_in_bytes, get_ultimate_context): Declare.

	* g++.dg/abi/empty12.C: New test.
	* g++.dg/abi/empty12.h: New test.
	* g++.dg/abi/empty12a.c: New test.
	* g++.dg/abi/empty13.C: New test.
	* g++.dg/abi/empty13.h: New test.
	* g++.dg/abi/empty13a.c: New test.
	* g++.dg/abi/empty14.C: New test.
	* g++.dg/abi/empty14.h: New test.
	* g++.dg/abi/empty14a.c: New test.
	* g++.dg/abi/empty15.C: New test.
	* g++.dg/abi/empty15.h: New test.
	* g++.dg/abi/empty15a.c: New test.
	* g++.dg/abi/empty16.C: New test.
	* g++.dg/abi/empty16.h: New test.
	* g++.dg/abi/empty16a.c: New test.
	* g++.dg/abi/empty17.C: New test.
	* g++.dg/abi/empty17.h: New test.
	* g++.dg/abi/empty17a.c: New test.
	* g++.dg/abi/empty18.C: New test.
	* g++.dg/abi/empty18.h: New test.
	* g++.dg/abi/empty18a.c: New test.
	* g++.dg/abi/empty19.C: New test.
	* g++.dg/abi/empty19.h: New test.
	* g++.dg/abi/empty19a.c: New test.
	* g++.dg/abi/empty20.C: New test.
	* g++.dg/abi/empty21.C: New test.
	* g++.dg/abi/empty22.C: New test.
	* g++.dg/abi/empty22.h: New test.
	* g++.dg/abi/empty22a.c: New test.
	* g++.dg/abi/empty23.C: New test.
	* g++.dg/abi/empty24.C: New test.
	* g++.dg/abi/empty25.C: New test.
	* g++.dg/abi/empty25.h: New test.
	* g++.dg/abi/empty25a.c: New test.
	* g++.dg/abi/empty26.C: New test.
	* g++.dg/abi/empty26.h: New test.
	* g++.dg/abi/empty26a.c: New test.
	* g++.dg/abi/empty27.C: New test.
	* g++.dg/abi/empty28.C: New test.
	* g++.dg/abi/pr60336-1.C: New test.
	* g++.dg/abi/pr60336-10.C: New test.
	* g++.dg/abi/pr60336-11.C: New test.
	* g++.dg/abi/pr60336-12.C: New test.
	* g++.dg/abi/pr60336-2.C: New test.
	* g++.dg/abi/pr60336-3.C: New test.
	* g++.dg/abi/pr60336-4.C: New test.
	* g++.dg/abi/pr60336-5.C: New test.
	* g++.dg/abi/pr60336-6.C: New test.
	* g++.dg/abi/pr60336-7.C: New test.
	* g++.dg/abi/pr60336-8.C: New test.
	* g++.dg/abi/pr60336-9.C: New test.
	* g++.dg/abi/pr68355.C: New test.
	* g++.dg/lto/pr60336_0.C: New test.

Co-Authored-By: H.J. Lu <hongjiu.lu@intel.com>
Co-Authored-By: Jason Merrill <jason@redhat.com>

From-SVN: r255066

1 files changed, 71 insertions, 0 deletions

diff --git a/gcc/tree.c b/gcc/tree.c
index 72da683..7efd644 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -8712,6 +8712,21 @@ get_containing_scope (const_tree t)
   return (TYPE_P (t) ? TYPE_CONTEXT (t) : DECL_CONTEXT (t));
 }
 
+/* Returns the ultimate TRANSLATION_UNIT_DECL context of DECL or NULL.  */
+
+const_tree
+get_ultimate_context (const_tree decl)
+{
+  while (decl && TREE_CODE (decl) != TRANSLATION_UNIT_DECL)
+    {
+      if (TREE_CODE (decl) == BLOCK)
+	decl = BLOCK_SUPERCONTEXT (decl);
+      else
+	decl = get_containing_scope (decl);
+    }
+  return decl;
+}
+
 /* Return the innermost context enclosing DECL that is
    a FUNCTION_DECL, or zero if none.  */
 
@@ -13822,6 +13837,62 @@ get_nonnull_args (const_tree fntype)
   return argmap;
 }
 
+/* Returns true if TYPE is a type where it and all of its subobjects
+   (recursively) are of structure, union, or array type.  */
+
+static bool
+default_is_empty_type (tree type)
+{
+  if (RECORD_OR_UNION_TYPE_P (type))
+    {
+      for (tree field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
+	if (TREE_CODE (field) == FIELD_DECL
+	    && !DECL_PADDING_P (field)
+	    && !default_is_empty_type (TREE_TYPE (field)))
+	  return false;
+      return true;
+    }
+  else if (TREE_CODE (type) == ARRAY_TYPE)
+    return (integer_minus_onep (array_type_nelts (type))
+	    || TYPE_DOMAIN (type) == NULL_TREE
+	    || default_is_empty_type (TREE_TYPE (type)));
+  return false;
+}
+
+/* Implement TARGET_EMPTY_RECORD_P.  Return true if TYPE is an empty type
+   that shouldn't be passed via stack.  */
+
+bool
+default_is_empty_record (const_tree type)
+{
+  if (!abi_version_at_least (12))
+    return false;
+
+  if (type == error_mark_node)
+    return false;
+
+  if (TREE_ADDRESSABLE (type))
+    return false;
+
+  return default_is_empty_type (TYPE_MAIN_VARIANT (type));
+}
+
+/* Like int_size_in_bytes, but handle empty records specially.  */
+
+HOST_WIDE_INT
+arg_int_size_in_bytes (const_tree type)
+{
+  return TYPE_EMPTY_P (type) ? 0 : int_size_in_bytes (type);
+}
+
+/* Like size_in_bytes, but handle empty records specially.  */
+
+tree
+arg_size_in_bytes (const_tree type)
+{
+  return TYPE_EMPTY_P (type) ? size_zero_node : size_in_bytes (type);
+}
+
 /* List of pointer types used to declare builtins before we have seen their
    real declaration.