Add LANG_HOOKS_EMPTY_RECORD_P for C++ empty classhjl/pr60336/hook

Empty record should be returned and passed the same way in C and C++.
This patch adds LANG_HOOKS_EMPTY_RECORD_P for C++ empty class, which
defaults to return false.  For C++, LANG_HOOKS_EMPTY_RECORD_P is defined
to is_really_empty_class, which returns true for C++ empty classes.  For
LTO, we stream out a bit to indicate if a record is empty and we store
it in TYPE_LANG_FLAG_0 when streaming in.  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.

gcc/

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* calls.c (initialize_argument_information): 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): Likewise.
	(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.
	* expr.c (block_move_libcall_safe_for_call_parm): Likewise.
	* function.c (aggregate_value_p): Replace
	targetm.calls.return_in_memory with return_in_memory.
	(assign_parm_find_entry_rtl): Replace
	targetm.calls.function_incoming_arg with function_incoming_arg.
	(assign_parms): 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.
	(function_arg_advance): New wrapper function.
	(function_arg): Likewise.
	(function_incoming_arg): Likewise.
	(return_in_memory): Likewise.
	* langhooks-def.h (LANG_HOOKS_EMPTY_RECORD_P): New.
	(LANG_HOOKS_DECLS): Add LANG_HOOKS_EMPTY_RECORD_P.
	* langhooks.h (lang_hooks_for_decls): Add empty_record_p.
	* lto-streamer.h (LTO_major_version): Increase by 1 to 6.
	* target.h (function_arg_advance): New prototype.
	(function_arg): Likewise.
	(function_incoming_arg): Likewise.
	(return_in_memory): Likewise.
	* targhooks.c: Include "langhooks.h".
	(std_gimplify_va_arg_expr): Use 0 for empty record size.
	* tree-dfa.c (get_ref_base_and_extent): Likewise.
	* tree-streamer-in.c (unpack_ts_base_value_fields): Stream in
	TYPE_LANG_FLAG_0.
	* tree-streamer-out.c: Include "langhooks.h".
	(pack_ts_base_value_fields): Stream out a bit to indicate if a
	record is empty.
	* 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.

gcc/cp/

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* class.c (is_empty_class): Changed to return bool and take
	const_tree.
	(is_really_empty_class): Changed to take const_tree.  Check
	if TYPE_BINFO is zero.
	* cp-tree.h (is_empty_class): Updated.
	(is_really_empty_class): Likewise.
	* cp-lang.c (LANG_HOOKS_EMPTY_RECORD_P): New.

gcc/lto/

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* lto-lang.c (lto_empty_record_p): New.
	(LANG_HOOKS_EMPTY_RECORD_P): Likewise.

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/pr60336-1.C: Likewise.
	* g++.dg/pr60336-2.C: Likewise.
	* g++.dg/pr68355.C: Likewise.

24 files changed, 284 insertions, 72 deletions

diff --git a/gcc/calls.c b/gcc/calls.c
index b56556a9d0a..ae1a62f9018 100644
--- a/gcc/calls.c
+++ b/gcc/calls.c
@@ -1391,8 +1391,8 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED,
       args[i].unsignedp = unsignedp;
       args[i].mode = mode;
 
-      args[i].reg = targetm.calls.function_arg (args_so_far, mode, type,
-						argpos < n_named_args);
+      args[i].reg = function_arg (args_so_far, mode, type,
+				  argpos < n_named_args);
 
       if (args[i].reg && CONST_INT_P (args[i].reg))
 	{
@@ -1405,8 +1405,8 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED,
 	 arguments have to go into the incoming registers.  */
       if (targetm.calls.function_incoming_arg != targetm.calls.function_arg)
 	args[i].tail_call_reg
-	  = targetm.calls.function_incoming_arg (args_so_far, mode, type,
-						 argpos < n_named_args);
+	  = function_incoming_arg (args_so_far, mode, type,
+				   argpos < n_named_args);
       else
 	args[i].tail_call_reg = args[i].reg;
 
@@ -1467,8 +1467,8 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED,
       /* Increment ARGS_SO_FAR, which has info about which arg-registers
 	 have been used, etc.  */
 
-      targetm.calls.function_arg_advance (args_so_far, TYPE_MODE (type),
-					  type, argpos < n_named_args);
+      function_arg_advance (args_so_far, TYPE_MODE (type), type,
+			    argpos < n_named_args);
     }
 }
 
@@ -3320,14 +3320,11 @@ expand_call (tree exp, rtx target, int ignore)
       /* Set up next argument register.  For sibling calls on machines
 	 with register windows this should be the incoming register.  */
       if (pass == 0)
-	next_arg_reg = targetm.calls.function_incoming_arg (args_so_far,
-							    VOIDmode,
-							    void_type_node,
-							    true);
+	next_arg_reg = function_incoming_arg (args_so_far, VOIDmode,
+					      void_type_node, true);
       else
-	next_arg_reg = targetm.calls.function_arg (args_so_far,
-						   VOIDmode, void_type_node,
-						   true);
+	next_arg_reg = function_arg (args_so_far, VOIDmode,
+				     void_type_node, true);
 
       if (pass == 1 && (return_flags & ERF_RETURNS_ARG))
 	{
@@ -3939,8 +3936,8 @@ emit_library_call_value_1 (int retval, rtx orgfun, rtx value,
       argvec[count].mode = Pmode;
       argvec[count].partial = 0;
 
-      argvec[count].reg = targetm.calls.function_arg (args_so_far,
-						      Pmode, NULL_TREE, true);
+      argvec[count].reg = function_arg (args_so_far, Pmode, NULL_TREE,
+					true);
       gcc_assert (targetm.calls.arg_partial_bytes (args_so_far, Pmode,
 						   NULL_TREE, 1) == 0);
 
@@ -3957,7 +3954,7 @@ emit_library_call_value_1 (int retval, rtx orgfun, rtx value,
 	  || reg_parm_stack_space > 0)
 	args_size.constant += argvec[count].locate.size.constant;
 
-      targetm.calls.function_arg_advance (args_so_far, Pmode, (tree) 0, true);
+      function_arg_advance (args_so_far, Pmode, (tree) 0, true);
 
       count++;
     }
@@ -4022,7 +4019,7 @@ emit_library_call_value_1 (int retval, rtx orgfun, rtx value,
       mode = promote_function_mode (NULL_TREE, mode, &unsigned_p, NULL_TREE, 0);
       argvec[count].mode = mode;
       argvec[count].value = convert_modes (mode, GET_MODE (val), val, unsigned_p);
-      argvec[count].reg = targetm.calls.function_arg (args_so_far, mode,
+      argvec[count].reg = function_arg (args_so_far, mode,
 						      NULL_TREE, true);
 
       argvec[count].partial
@@ -4052,7 +4049,7 @@ emit_library_call_value_1 (int retval, rtx orgfun, rtx value,
 			     GET_MODE_SIZE (mode) <= UNITS_PER_WORD);
 #endif
 
-      targetm.calls.function_arg_advance (args_so_far, mode, (tree) 0, true);
+      function_arg_advance (args_so_far, mode, (tree) 0, true);
     }
 
   /* If this machine requires an external definition for library
@@ -4399,8 +4396,7 @@ emit_library_call_value_1 (int retval, rtx orgfun, rtx value,
 	       build_function_type (tfom, NULL_TREE),
 	       original_args_size.constant, args_size.constant,
 	       struct_value_size,
-	       targetm.calls.function_arg (args_so_far,
-					   VOIDmode, void_type_node, true),
+	       function_arg (args_so_far, VOIDmode, void_type_node, true),
 	       valreg,
 	       old_inhibit_defer_pop + 1, call_fusage, flags, args_so_far);
 
@@ -4835,7 +4831,10 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 	 Note that in C the default argument promotions
 	 will prevent such mismatches.  */
 
-      size = GET_MODE_SIZE (arg->mode);
+      if (lang_hooks.decls.empty_record_p (TREE_TYPE (pval)))
+	size = 0;
+      else
+	size = GET_MODE_SIZE (arg->mode);
       /* Compute how much space the push instruction will push.
 	 On many machines, pushing a byte will advance the stack
 	 pointer by a halfword.  */
@@ -4865,10 +4864,14 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 
       /* This isn't already where we want it on the stack, so put it there.
 	 This can either be done with push or copy insns.  */
-      if (!emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval), NULL_RTX,
-		      parm_align, partial, reg, used - size, argblock,
-		      ARGS_SIZE_RTX (arg->locate.offset), reg_parm_stack_space,
-		      ARGS_SIZE_RTX (arg->locate.alignment_pad), true))
+      if (used
+	  && !emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval),
+			      NULL_RTX, parm_align, partial, reg,
+			      used - size, argblock,
+			      ARGS_SIZE_RTX (arg->locate.offset),
+			      reg_parm_stack_space,
+			      ARGS_SIZE_RTX (arg->locate.alignment_pad),
+			      true))
 	sibcall_failure = 1;
 
       /* Unless this is a partially-in-register argument, the argument is now
@@ -4900,10 +4903,16 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 	{
 	  /* PUSH_ROUNDING has no effect on us, because emit_push_insn
 	     for BLKmode is careful to avoid it.  */
+	  bool empty_record
+	    = lang_hooks.decls.empty_record_p (TREE_TYPE (pval));
 	  excess = (arg->locate.size.constant
-		    - int_size_in_bytes (TREE_TYPE (pval))
+		    - (empty_record
+		       ? 0
+		       : int_size_in_bytes (TREE_TYPE (pval)))
 		    + partial);
-	  size_rtx = expand_expr (size_in_bytes (TREE_TYPE (pval)),
+	  size_rtx = expand_expr ((empty_record
+				   ? size_zero_node
+				   : size_in_bytes (TREE_TYPE (pval))),
 				  NULL_RTX, TYPE_MODE (sizetype),
 				  EXPAND_NORMAL);
 	}
@@ -4971,10 +4980,13 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 	    }
 	}
 
-      emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval), size_rtx,
-		      parm_align, partial, reg, excess, argblock,
-		      ARGS_SIZE_RTX (arg->locate.offset), reg_parm_stack_space,
-		      ARGS_SIZE_RTX (arg->locate.alignment_pad), false);
+      if (!CONST_INT_P (size_rtx) || INTVAL (size_rtx) != 0)
+	emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval),
+			size_rtx, parm_align, partial, reg, excess,
+			argblock, ARGS_SIZE_RTX (arg->locate.offset),
+			reg_parm_stack_space,
+			ARGS_SIZE_RTX (arg->locate.alignment_pad),
+			false);
 
       /* Unless this is a partially-in-register argument, the argument is now
 	 in the stack.
@@ -5052,6 +5064,9 @@ must_pass_in_stack_var_size_or_pad (machine_mode mode, const_tree type)
   if (TREE_ADDRESSABLE (type))
     return true;
 
+  if (lang_hooks.decls.empty_record_p (type))
+    return false;
+
   /* If the padding and mode of the type is such that a copy into
      a register would put it into the wrong part of the register.  */
   if (mode == BLKmode
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 83749d59f3e..4520979a3f0 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -10277,7 +10277,8 @@ ix86_gimplify_va_arg (tree valist, tree type, gimple_seq *pre_p,
   indirect_p = pass_by_reference (NULL, TYPE_MODE (type), type, false);
   if (indirect_p)
     type = build_pointer_type (type);
-  size = int_size_in_bytes (type);
+  bool empty_record = type && lang_hooks.decls.empty_record_p (type);
+  size = empty_record ? 0 : int_size_in_bytes (type);
   rsize = CEIL (size, UNITS_PER_WORD);
 
   nat_mode = type_natural_mode (type, NULL, false);
diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 216a30141d4..c3807346112 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -8068,8 +8068,8 @@ build_self_reference (void)
 
 /* Returns 1 if TYPE contains only padding bytes.  */
 
-int
-is_empty_class (tree type)
+bool
+is_empty_class (const_tree type)
 {
   if (type == error_mark_node)
     return 0;
@@ -8084,7 +8084,7 @@ is_empty_class (tree type)
    possible combinations of empty classes and possibly a vptr.  */
 
 bool
-is_really_empty_class (tree type)
+is_really_empty_class (const_tree type)
 {
   if (CLASS_TYPE_P (type))
     {
@@ -8098,10 +8098,13 @@ is_really_empty_class (tree type)
       if (COMPLETE_TYPE_P (type) && is_empty_class (type))
 	return true;
 
-      for (binfo = TYPE_BINFO (type), i = 0;
-	   BINFO_BASE_ITERATE (binfo, i, base_binfo); ++i)
-	if (!is_really_empty_class (BINFO_TYPE (base_binfo)))
-	  return false;
+      /* TYPE_BINFO may be zeron when is_really_empty_class is called
+	 from LANG_HOOKS_EMPTY_RECORD_P.  */
+      binfo = TYPE_BINFO (type);
+      if (binfo)
+	for (i = 0; BINFO_BASE_ITERATE (binfo, i, base_binfo); ++i)
+	  if (!is_really_empty_class (BINFO_TYPE (base_binfo)))
+	    return false;
       for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
 	if (TREE_CODE (field) == FIELD_DECL
 	    && !DECL_ARTIFICIAL (field)
diff --git a/gcc/cp/cp-lang.c b/gcc/cp/cp-lang.c
index 048108d4f02..80174cb4d2c 100644
--- a/gcc/cp/cp-lang.c
+++ b/gcc/cp/cp-lang.c
@@ -78,6 +78,8 @@ static tree cxx_enum_underlying_base_type (const_tree);
 #define LANG_HOOKS_EH_RUNTIME_TYPE build_eh_type_type
 #undef LANG_HOOKS_ENUM_UNDERLYING_BASE_TYPE
 #define LANG_HOOKS_ENUM_UNDERLYING_BASE_TYPE cxx_enum_underlying_base_type
+#undef LANG_HOOKS_EMPTY_RECORD_P
+#define LANG_HOOKS_EMPTY_RECORD_P is_really_empty_class
 
 /* Each front end provides its own lang hook initializer.  */
 struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 1672291f9b6..e6165f83469 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -5583,8 +5583,8 @@ extern tree finish_struct			(tree, tree);
 extern void finish_struct_1			(tree);
 extern int resolves_to_fixed_type_p		(tree, int *);
 extern void init_class_processing		(void);
-extern int is_empty_class			(tree);
-extern bool is_really_empty_class		(tree);
+extern bool is_empty_class			(const_tree);
+extern bool is_really_empty_class		(const_tree);
 extern void pushclass				(tree);
 extern void popclass				(void);
 extern void push_nested_class			(tree);
diff --git a/gcc/dse.c b/gcc/dse.c
index 35eef719ec3..594106f7c16 100644
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -2366,7 +2366,7 @@ get_call_args (rtx call_insn, tree fn, rtx *args, int nargs)
     {
       machine_mode mode = TYPE_MODE (TREE_VALUE (arg));
       rtx reg, link, tmp;
-      reg = targetm.calls.function_arg (args_so_far, mode, NULL_TREE, true);
+      reg = function_arg (args_so_far, mode, NULL_TREE, true);
       if (!reg || !REG_P (reg) || GET_MODE (reg) != mode
 	  || GET_MODE_CLASS (mode) != MODE_INT)
 	return false;
@@ -2400,7 +2400,7 @@ get_call_args (rtx call_insn, tree fn, rtx *args, int nargs)
       if (tmp)
 	args[idx] = tmp;
 
-      targetm.calls.function_arg_advance (args_so_far, mode, NULL_TREE, true);
+      function_arg_advance (args_so_far, mode, NULL_TREE, true);
     }
   if (arg != void_list_node || idx != nargs)
     return false;
diff --git a/gcc/expr.c b/gcc/expr.c
index bd43dc4f3fd..384581a7b08 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -1198,13 +1198,12 @@ block_move_libcall_safe_for_call_parm (void)
     for ( ; arg != void_list_node ; arg = TREE_CHAIN (arg))
       {
 	machine_mode mode = TYPE_MODE (TREE_VALUE (arg));
-	rtx tmp = targetm.calls.function_arg (args_so_far, mode,
-					      NULL_TREE, true);
+	rtx tmp = function_arg (args_so_far, mode, NULL_TREE, true);
 	if (!tmp || !REG_P (tmp))
 	  return false;
 	if (targetm.calls.arg_partial_bytes (args_so_far, mode, NULL, 1))
 	  return false;
-	targetm.calls.function_arg_advance (args_so_far, mode,
+	function_arg_advance (args_so_far, mode,
 					    NULL_TREE, true);
       }
   }
diff --git a/gcc/function.c b/gcc/function.c
index afc2c87dbcc..f567f4867a5 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -2073,7 +2073,7 @@ aggregate_value_p (const_tree exp, const_tree fntype)
   if (flag_pcc_struct_return && AGGREGATE_TYPE_P (type))
     return 1;
 
-  if (targetm.calls.return_in_memory (type, fntype))
+  if (return_in_memory (type, fntype))
     return 1;
 
   /* Make sure we have suitable call-clobbered regs to return
@@ -2523,10 +2523,10 @@ assign_parm_find_entry_rtl (struct assign_parm_data_all *all,
       return;
     }
 
-  entry_parm = targetm.calls.function_incoming_arg (all->args_so_far,
-						    data->promoted_mode,
-						    data->passed_type,
-						    data->named_arg);
+  entry_parm = function_incoming_arg (all->args_so_far,
+				      data->promoted_mode,
+				      data->passed_type,
+				      data->named_arg);
 
   if (entry_parm == 0)
     data->promoted_mode = data->passed_mode;
@@ -2550,9 +2550,9 @@ assign_parm_find_entry_rtl (struct assign_parm_data_all *all,
       if (targetm.calls.pretend_outgoing_varargs_named (all->args_so_far))
 	{
 	  rtx tem;
-	  tem = targetm.calls.function_incoming_arg (all->args_so_far,
-						     data->promoted_mode,
-						     data->passed_type, true);
+	  tem = function_incoming_arg (all->args_so_far,
+				       data->promoted_mode,
+				       data->passed_type, true);
 	  in_regs = tem != NULL;
 	}
     }
@@ -3752,8 +3752,8 @@ assign_parms (tree fndecl)
 	}
 
       /* Update info on where next arg arrives in registers.  */
-      targetm.calls.function_arg_advance (all.args_so_far, data.promoted_mode,
-					  data.passed_type, data.named_arg);
+      function_arg_advance (all.args_so_far, data.promoted_mode,
+			    data.passed_type, data.named_arg);
 
       if (POINTER_BOUNDS_TYPE_P (data.passed_type))
 	bound_no++;
@@ -3949,8 +3949,8 @@ gimplify_parameters (void)
 	continue;
 
       /* Update info on where next arg arrives in registers.  */
-      targetm.calls.function_arg_advance (all.args_so_far, data.promoted_mode,
-					  data.passed_type, data.named_arg);
+      function_arg_advance (all.args_so_far, data.promoted_mode,
+			    data.passed_type, data.named_arg);
 
       /* ??? Once upon a time variable_size stuffed parameter list
 	 SAVE_EXPRs (amongst others) onto a pending sizes list.  This
@@ -4093,8 +4093,11 @@ locate_and_pad_parm (machine_mode passed_mode, tree type, int in_regs,
 
   part_size_in_regs = (reg_parm_stack_space == 0 ? partial : 0);
 
-  sizetree
-    = type ? size_in_bytes (type) : size_int (GET_MODE_SIZE (passed_mode));
+  if (type)
+    sizetree = (lang_hooks.decls.empty_record_p (type)
+		? size_zero_node : size_in_bytes (type));
+  else
+    sizetree = size_int (GET_MODE_SIZE (passed_mode));
   where_pad = FUNCTION_ARG_PADDING (passed_mode, type);
   boundary = targetm.calls.function_arg_boundary (passed_mode, type);
   round_boundary = targetm.calls.function_arg_round_boundary (passed_mode,
@@ -6821,5 +6824,52 @@ make_pass_match_asm_constraints (gcc::context *ctxt)
   return new pass_match_asm_constraints (ctxt);
 }
 
+/* Wrapper for targetm.calls.function_arg_advance.  */
+
+void
+function_arg_advance (cumulative_args_t ca, machine_mode mode,
+		      const_tree type, bool named)
+{
+  if (type && lang_hooks.decls.empty_record_p (type))
+    return;
+
+  targetm.calls.function_arg_advance (ca, mode, type, named);
+}
+
+/* Wrapper for targetm.calls.function_arg.  */
+
+rtx
+function_arg (cumulative_args_t ca, machine_mode mode, const_tree type,
+	      bool named)
+{
+  if (type && lang_hooks.decls.empty_record_p (type))
+    return NULL;
+
+  return targetm.calls.function_arg (ca, mode, type, named);
+}
+
+/* Wrapper for targetm.calls.function_incoming_arg.  */
+
+rtx
+function_incoming_arg (cumulative_args_t ca, machine_mode mode,
+		       const_tree type, bool named)
+{
+  if (type && lang_hooks.decls.empty_record_p (type))
+    return NULL;
+
+  return targetm.calls.function_incoming_arg (ca, mode, type, named);
+}
+
+/* Wrapper for targetm.calls.return_in_memory.  */
+
+bool
+return_in_memory (const_tree type, const_tree fntype)
+{
+  if (type && lang_hooks.decls.empty_record_p (type))
+    return false;
+
+  return targetm.calls.return_in_memory (type, fntype);
+}
+
 
 #include "gt-function.h"
diff --git a/gcc/langhooks-def.h b/gcc/langhooks-def.h
index 18ac84d9df3..df4cbf821a4 100644
--- a/gcc/langhooks-def.h
+++ b/gcc/langhooks-def.h
@@ -163,6 +163,7 @@ extern tree lhd_make_node (enum tree_code);
 #define LANG_HOOKS_GENERIC_GENERIC_PARAMETER_DECL_P hook_bool_const_tree_false
 #define LANG_HOOKS_FUNCTION_PARM_EXPANDED_FROM_PACK_P \
 					hook_bool_tree_tree_false
+#define LANG_HOOKS_EMPTY_RECORD_P	hook_bool_const_tree_false
 #define LANG_HOOKS_GET_GENERIC_FUNCTION_DECL hook_tree_const_tree_null
 #define LANG_HOOKS_TYPE_PROMOTES_TO lhd_type_promotes_to
 #define LANG_HOOKS_REGISTER_BUILTIN_TYPE lhd_register_builtin_type
@@ -228,6 +229,7 @@ extern tree lhd_make_node (enum tree_code);
   LANG_HOOKS_FUNCTION_DECL_DELETED_P, \
   LANG_HOOKS_GENERIC_GENERIC_PARAMETER_DECL_P, \
   LANG_HOOKS_FUNCTION_PARM_EXPANDED_FROM_PACK_P, \
+  LANG_HOOKS_EMPTY_RECORD_P, \
   LANG_HOOKS_GET_GENERIC_FUNCTION_DECL, \
   LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL, \
   LANG_HOOKS_POST_COMPILATION_PARSING_CLEANUPS, \
diff --git a/gcc/langhooks.h b/gcc/langhooks.h
index d8d01fa3b87..450bdee968d 100644
--- a/gcc/langhooks.h
+++ b/gcc/langhooks.h
@@ -177,6 +177,9 @@ struct lang_hooks_for_decls
      function parameter pack.  */
   bool (*function_parm_expanded_from_pack_p) (tree, tree);
 
+  /* Determine if a type is an empty record.  */
+  bool (*empty_record_p) (const_tree type);
+
   /* Returns the generic declaration of a generic function instantiations.  */
   tree (*get_generic_function_decl) (const_tree);
 
diff --git a/gcc/lto-streamer.h b/gcc/lto-streamer.h
index 5aae9e9bfa7..cc4cede8a4f 100644
--- a/gcc/lto-streamer.h
+++ b/gcc/lto-streamer.h
@@ -128,7 +128,7 @@ along with GCC; see the file COPYING3.  If not see
      String are represented in the table as pairs, a length in ULEB128
      form followed by the data for the string.  */
 
-#define LTO_major_version 5
+#define LTO_major_version 6
 #define LTO_minor_version 0
 
 typedef unsigned char	lto_decl_flags_t;
diff --git a/gcc/lto/lto-lang.c b/gcc/lto/lto-lang.c
index 53dd8f6df55..dc849a4f354 100644
--- a/gcc/lto/lto-lang.c
+++ b/gcc/lto/lto-lang.c
@@ -1306,6 +1306,16 @@ static void lto_init_ts (void)
   tree_contains_struct[NAMESPACE_DECL][TS_DECL_MINIMAL] = 1;
 }
 
+/* Return true if TYPE contains no actual data, just various possible
+   combinations of empty records.  */
+
+static bool
+lto_empty_record_p (const_tree type)
+{
+  /* Set if a record is empty.  */
+  return TYPE_LANG_FLAG_0 (type);
+}
+
 #undef LANG_HOOKS_NAME
 #define LANG_HOOKS_NAME "GNU GIMPLE"
 #undef LANG_HOOKS_OPTION_LANG_MASK
@@ -1363,6 +1373,9 @@ static void lto_init_ts (void)
 #undef LANG_HOOKS_INIT_TS
 #define LANG_HOOKS_INIT_TS lto_init_ts
 
+#undef LANG_HOOKS_EMPTY_RECORD_P
+#define LANG_HOOKS_EMPTY_RECORD_P lto_empty_record_p
+
 struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
 
 /* Language hooks that are not part of lang_hooks.  */
diff --git a/gcc/target.h b/gcc/target.h
index ffc4d6aef54..eb01a76352f 100644
--- a/gcc/target.h
+++ b/gcc/target.h
@@ -104,6 +104,14 @@ extern bool target_default_pointer_address_modes_p (void);
    behaviour.  */
 extern unsigned int get_move_ratio (bool);
 
+extern void function_arg_advance (cumulative_args_t, machine_mode,
+				  const_tree, bool);
+extern rtx function_arg (cumulative_args_t, machine_mode, const_tree,
+			 bool);
+extern rtx function_incoming_arg (cumulative_args_t, machine_mode,
+				  const_tree, bool);
+extern bool return_in_memory (const_tree, const_tree);
+
 struct stdarg_info;
 struct spec_info_def;
 struct hard_reg_set_container;
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index 01d3686299b..94869d20c6c 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -74,6 +74,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "intl.h"
 #include "opts.h"
 #include "gimplify.h"
+#include "langhooks.h"
 
 
 bool
@@ -1829,9 +1830,12 @@ std_gimplify_va_arg_expr (tree valist, tree type, gimple_seq *pre_p,
   /* Hoist the valist value into a temporary for the moment.  */
   valist_tmp = get_initialized_tmp_var (valist, pre_p, NULL);
 
+  bool empty_record = lang_hooks.decls.empty_record_p (type);
+
   /* va_list pointer is aligned to PARM_BOUNDARY.  If argument actually
      requires greater alignment, we must perform dynamic alignment.  */
   if (boundary > align
+      && !empty_record
       && !integer_zerop (TYPE_SIZE (type)))
     {
       t = build2 (MODIFY_EXPR, TREE_TYPE (valist), valist_tmp,
@@ -1858,7 +1862,7 @@ std_gimplify_va_arg_expr (tree valist, tree type, gimple_seq *pre_p,
     }
 
   /* Compute the rounded size of the type.  */
-  type_size = size_in_bytes (type);
+  type_size = empty_record ? size_zero_node : size_in_bytes (type);
   rounded_size = round_up (type_size, align);
 
   /* Reduce rounded_size so it's sharable with the postqueue.  */
diff --git a/gcc/testsuite/g++.dg/abi/empty12.C b/gcc/testsuite/g++.dg/abi/empty12.C
new file mode 100644
index 00000000000..430d57dbfce
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/empty12.C
@@ -0,0 +1,17 @@
+// PR c++/60336
+// { dg-do run }
+// { dg-options "-x c" }
+// { dg-additional-sources "empty12a.c" }
+// { dg-prune-output "command line option" }
+
+#include "empty12.h"
+extern "C" void fun(struct dummy, struct foo);
+
+int main()
+{
+  struct dummy d;
+  struct foo f = { -1, -2, -3, -4, -5 };
+
+  fun(d, f);
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/abi/empty12.h b/gcc/testsuite/g++.dg/abi/empty12.h
new file mode 100644
index 00000000000..c61afcda0fb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/empty12.h
@@ -0,0 +1,9 @@
+struct dummy { };
+struct foo
+{
+  int i1;
+  int i2;
+  int i3;
+  int i4;
+  int i5;
+};
diff --git a/gcc/testsuite/g++.dg/abi/empty12a.c b/gcc/testsuite/g++.dg/abi/empty12a.c
new file mode 100644
index 00000000000..34a25bad75d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/empty12a.c
@@ -0,0 +1,6 @@
+#include "empty12.h"
+void fun(struct dummy d, struct foo f)
+{
+  if (f.i1 != -1)
+    __builtin_abort();
+}
diff --git a/gcc/testsuite/g++.dg/pr60336-1.C b/gcc/testsuite/g++.dg/pr60336-1.C
new file mode 100644
index 00000000000..af0863887a0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr60336-1.C
@@ -0,0 +1,17 @@
+// { dg-do compile }
+// { dg-options "-O2 -std=c++11 -fno-pic" }
+// { dg-require-effective-target fpic }
+
+struct dummy { };
+struct true_type { struct dummy i; };
+
+extern true_type y;
+extern void xxx (true_type c);
+
+void
+yyy (void)
+{
+  xxx (y);
+}
+
+// { dg-final { scan-assembler "jmp\[\t \]+\[^\$\]*?_Z3xxx9true_type" { target i?86-*-* x86_64-*-* } } }
diff --git a/gcc/testsuite/g++.dg/pr60336-2.C b/gcc/testsuite/g++.dg/pr60336-2.C
new file mode 100644
index 00000000000..7b902e8e894
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr60336-2.C
@@ -0,0 +1,28 @@
+// { dg-do run }
+// { dg-options "-O2" }
+
+#include <stdarg.h>
+
+struct dummy { struct{}__attribute__((aligned (4))) a[7]; };
+
+void
+test (struct dummy a, ...)
+{
+  va_list va_arglist;
+  int i;
+
+  va_start (va_arglist, a);
+  i = va_arg (va_arglist, int);
+  if (i != 0x10)
+    __builtin_abort ();
+  va_end (va_arglist);
+}
+
+struct dummy a0;
+
+int
+main ()
+{
+  test (a0, 0x10);
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/pr68355.C b/gcc/testsuite/g++.dg/pr68355.C
new file mode 100644
index 00000000000..1354fc497b5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr68355.C
@@ -0,0 +1,24 @@
+// { dg-do compile }
+// { dg-options "-O2 -std=c++11 -fno-pic" }
+// { dg-require-effective-target fpic }
+
+template<typename _Tp, _Tp __v>
+struct integral_constant
+{
+  static constexpr _Tp value = __v;
+  typedef _Tp value_type;
+  typedef integral_constant<_Tp, __v> type;
+  constexpr operator value_type() const { return value; }
+};
+
+typedef integral_constant<bool, true> true_type;
+extern void xxx (true_type c);
+
+void
+yyy (void)
+{
+  true_type y;
+  xxx (y);
+}
+
+// { dg-final { scan-assembler "jmp\[\t \]+\[^\$\]*?_Z3xxx17integral_constantIbLb1EE" { target i?86-*-* x86_64-*-* } } }
diff --git a/gcc/tree-dfa.c b/gcc/tree-dfa.c
index bb5cd496126..6b1e25d744f 100644
--- a/gcc/tree-dfa.c
+++ b/gcc/tree-dfa.c
@@ -394,6 +394,8 @@ get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
       machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
       if (mode == BLKmode)
 	size_tree = TYPE_SIZE (TREE_TYPE (exp));
+      else if (lang_hooks.decls.empty_record_p (TREE_TYPE (exp)))
+	bitsize = 0;
       else
 	bitsize = int (GET_MODE_PRECISION (mode));
     }
diff --git a/gcc/tree-streamer-in.c b/gcc/tree-streamer-in.c
index 65a1ce3bef4..672acde2b21 100644
--- a/gcc/tree-streamer-in.c
+++ b/gcc/tree-streamer-in.c
@@ -154,6 +154,11 @@ unpack_ts_base_value_fields (struct bitpack_d *bp, tree expr)
     }
   else
     bp_unpack_value (bp, 9);
+  if (TYPE_P (expr))
+    /* Set if a record is empty.  */
+    TYPE_LANG_FLAG_0 (expr) = (unsigned) bp_unpack_value (bp, 1);
+  else
+    bp_unpack_value (bp, 1);
 }
 
 
diff --git a/gcc/tree-streamer-out.c b/gcc/tree-streamer-out.c
index d0b7f6db171..a1bf96223bf 100644
--- a/gcc/tree-streamer-out.c
+++ b/gcc/tree-streamer-out.c
@@ -31,6 +31,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "alias.h"
 #include "stor-layout.h"
 #include "gomp-constants.h"
+#include "langhooks.h"
 
 
 /* Output the STRING constant to the string
@@ -128,6 +129,11 @@ pack_ts_base_value_fields (struct bitpack_d *bp, tree expr)
     }
   else
     bp_pack_value (bp, 0, 9);
+  if (TYPE_P (expr))
+    /* Stream out a bit to indicate if a record is empty.  */
+    bp_pack_value (bp, lang_hooks.decls.empty_record_p (expr), 1);
+  else
+    bp_pack_value (bp, 0, 1);
 }
 
 
diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index 9185bfd39cf..e9fdbe9ce5f 100644
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -6140,10 +6140,10 @@ prepare_call_arguments (basic_block bb, rtx_insn *insn)
 		  rtx reg;
 		  INIT_CUMULATIVE_ARGS (args_so_far_v, type, NULL_RTX, fndecl,
 					nargs + 1);
-		  reg = targetm.calls.function_arg (args_so_far, mode,
-						    struct_addr, true);
-		  targetm.calls.function_arg_advance (args_so_far, mode,
-						      struct_addr, true);
+		  reg = function_arg (args_so_far, mode, struct_addr,
+				      true);
+		  function_arg_advance (args_so_far, mode, struct_addr,
+					true);
 		  if (reg == NULL_RTX)
 		    {
 		      for (; link; link = XEXP (link, 1))
@@ -6164,8 +6164,8 @@ prepare_call_arguments (basic_block bb, rtx_insn *insn)
 		  machine_mode mode;
 		  t = TYPE_ARG_TYPES (type);
 		  mode = TYPE_MODE (TREE_VALUE (t));
-		  this_arg = targetm.calls.function_arg (args_so_far, mode,
-							 TREE_VALUE (t), true);
+		  this_arg = function_arg (args_so_far, mode,
+					   TREE_VALUE (t), true);
 		  if (this_arg && !REG_P (this_arg))
 		    this_arg = NULL_RTX;
 		  else if (this_arg == NULL_RTX)
@@ -6280,8 +6280,7 @@ prepare_call_arguments (basic_block bb, rtx_insn *insn)
 		argtype = build_pointer_type (argtype);
 		mode = TYPE_MODE (argtype);
 	      }
-	    reg = targetm.calls.function_arg (args_so_far, mode,
-					      argtype, true);
+	    reg = function_arg (args_so_far, mode, argtype, true);
 	    if (TREE_CODE (argtype) == REFERENCE_TYPE
 		&& INTEGRAL_TYPE_P (TREE_TYPE (argtype))
 		&& reg
@@ -6335,8 +6334,7 @@ prepare_call_arguments (basic_block bb, rtx_insn *insn)
 			}
 		  }
 	      }
-	    targetm.calls.function_arg_advance (args_so_far, mode,
-						argtype, true);
+	    function_arg_advance (args_so_far, mode, argtype, true);
 	    t = TREE_CHAIN (t);
 	  }
       }