Add a pass_by_reference flag to function_arg_info

This patch adds a flag that tells targets whether an argument
has been converted to pass-by-reference form.  This replaces
assign_parm_data_one::passed_pointer in function.c.

The flag is set automatically for places that call
apply_pass_by_reference_rules.  Places that apply
pass-by-reference manually need to set it themselves.

(After previous changes, no targets apply pass-by-reference
manually.  They all go through apply_pass_by_reference_rules.)

2019-08-20  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* calls.h (function_arg_info): Add a pass_by_reference field,
	defaulting to false.
	* calls.c (apply_pass_by_reference_rules): Set pass_by_reference
	when applying pass-by-reference semantics.
	(initialize_argument_information): Likewise.
	(emit_library_call_value_1): Likewise.
	* function.c (assign_parm_data_one): Remove passed_pointer field.
	(assign_parm_find_data_types): Don't set it.
	(assign_parm_find_stack_rtl, assign_parm_adjust_stack_rtl)
	(assign_parm_setup_reg, assign_parms, gimplify_parameters): Use
	arg.pass_by_reference instead of passed_pointer.

From-SVN: r274707

gcc/ChangeLog

 2019-08-20  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* calls.h (function_arg_info): Add a pass_by_reference field,
+	defaulting to false.
+	* calls.c (apply_pass_by_reference_rules): Set pass_by_reference
+	when applying pass-by-reference semantics.
+	(initialize_argument_information): Likewise.
+	(emit_library_call_value_1): Likewise.
+	* function.c (assign_parm_data_one): Remove passed_pointer field.
+	(assign_parm_find_data_types): Don't set it.
+	(assign_parm_find_stack_rtl, assign_parm_adjust_stack_rtl)
+	(assign_parm_setup_reg, assign_parms, gimplify_parameters): Use
+	arg.pass_by_reference instead of passed_pointer.
+
+2019-08-20  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* calls.c (emit_library_call_value_1): Merge arg and orig_arg
 	into a single function_arg_info, updating its fields when we
 	apply pass-by-reference and promotion semantics.  Use the

gcc/calls.c

@@ -946,6 +946,7 @@ apply_pass_by_reference_rules (CUMULATIVE_ARGS *ca, function_arg_info &arg)
     {
       arg.type = build_pointer_type (arg.type);
       arg.mode = TYPE_MODE (arg.type);
+      arg.pass_by_reference = true;
       return true;
     }
   return false;
@@ -2125,6 +2126,7 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED,
 					      "argument must be passed"
 					      " by copying");
 	    }
+	  arg.pass_by_reference = true;
 	}
 
       unsignedp = TYPE_UNSIGNED (type);
@@ -4957,6 +4959,7 @@ emit_library_call_value_1 (int retval, rtx orgfun, rtx value,
 					     call_fusage);
 
 	  arg.mode = Pmode;
+	  arg.pass_by_reference = true;
 	  val = force_operand (XEXP (slot, 0), NULL_RTX);
 	}
 

gcc/calls.h

@@ -34,21 +34,25 @@ along with GCC; see the file COPYING3.  If not see
 class function_arg_info
 {
 public:
-  function_arg_info () : type (NULL_TREE), mode (VOIDmode), named (false) {}
+  function_arg_info ()
+    : type (NULL_TREE), mode (VOIDmode), named (false),
+      pass_by_reference (false)
+  {}
 
   /* Initialize an argument of mode MODE, either before or after promotion.  */
   function_arg_info (machine_mode mode, bool named)
-    : type (NULL_TREE), mode (mode), named (named)
+    : type (NULL_TREE), mode (mode), named (named), pass_by_reference (false)
   {}
 
   /* Initialize an unpromoted argument of type TYPE.  */
   function_arg_info (tree type, bool named)
-    : type (type), mode (TYPE_MODE (type)), named (named)
+    : type (type), mode (TYPE_MODE (type)), named (named),
+      pass_by_reference (false)
   {}
 
   /* Initialize an argument with explicit properties.  */
   function_arg_info (tree type, machine_mode mode, bool named)
-    : type (type), mode (mode), named (named)
+    : type (type), mode (mode), named (named), pass_by_reference (false)
   {}
 
   /* Return true if the gimple-level type is an aggregate.  */
@@ -100,6 +104,10 @@ public:
      treated as an unnamed variadic argument (i.e. one passed through
      "...").  See also TARGET_STRICT_ARGUMENT_NAMING.  */
   unsigned int named : 1;
+
+  /* True if we have decided to pass the argument by reference, in which case
+     the function_arg_info describes a pointer to the original argument.  */
+  unsigned int pass_by_reference : 1;
 };
 
 extern int flags_from_decl_or_type (const_tree);

gcc/function.c

@@ -2271,7 +2271,6 @@ struct assign_parm_data_one
   machine_mode passed_mode;
   struct locate_and_pad_arg_data locate;
   int partial;
-  BOOL_BITFIELD passed_pointer : 1;
 };
 
 /* A subroutine of assign_parms.  Initialize ALL.  */
@@ -2453,7 +2452,6 @@ assign_parm_find_data_types (struct assign_parm_data_all *all, tree parm,
   if (apply_pass_by_reference_rules (&all->args_so_far_v, data->arg))
     {
       data->nominal_type = data->arg.type;
-      data->passed_pointer = true;
       data->passed_mode = data->nominal_mode = data->arg.mode;
     }
 
@@ -2653,7 +2651,7 @@ assign_parm_find_stack_rtl (tree parm, struct assign_parm_data_one *data)
     stack_parm = gen_rtx_PLUS (Pmode, stack_parm, offset_rtx);
   stack_parm = gen_rtx_MEM (data->arg.mode, stack_parm);
 
-  if (!data->passed_pointer)
+  if (!data->arg.pass_by_reference)
     {
       set_mem_attributes (stack_parm, parm, 1);
       /* set_mem_attributes could set MEM_SIZE to the passed mode's size,
@@ -2827,7 +2825,7 @@ assign_parm_adjust_stack_rtl (struct assign_parm_data_one *data)
      pointers in their passed stack slots.  */
   else if (crtl->stack_protect_guard
 	   && (flag_stack_protect == 2
-	       || data->passed_pointer
+	       || data->arg.pass_by_reference
 	       || POINTER_TYPE_P (data->nominal_type)))
     stack_parm = NULL;
 
@@ -3140,7 +3138,7 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
 
   /* If this was an item that we received a pointer to,
      set rtl appropriately.  */
-  if (data->passed_pointer)
+  if (data->arg.pass_by_reference)
     {
       rtl = gen_rtx_MEM (TYPE_MODE (TREE_TYPE (data->arg.type)), parmreg);
       set_mem_attributes (rtl, parm, 1);
@@ -3310,7 +3308,7 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
 
   /* If we were passed a pointer but the actual value can safely live
      in a register, retrieve it and use it directly.  */
-  if (data->passed_pointer && TYPE_MODE (TREE_TYPE (parm)) != BLKmode)
+  if (data->arg.pass_by_reference && TYPE_MODE (TREE_TYPE (parm)) != BLKmode)
     {
       /* We can't use nominal_mode, because it will have been set to
 	 Pmode above.  We must use the actual mode of the parm.  */
@@ -3630,7 +3628,7 @@ assign_parms (tree fndecl)
 	  assign_parm_adjust_entry_rtl (&data);
 	}
       /* Record permanently how this parm was passed.  */
-      if (data.passed_pointer)
+      if (data.arg.pass_by_reference)
 	{
 	  rtx incoming_rtl
 	    = gen_rtx_MEM (TYPE_MODE (TREE_TYPE (data.arg.type)),
@@ -3644,7 +3642,7 @@ assign_parms (tree fndecl)
 
       if (assign_parm_setup_block_p (&data))
 	assign_parm_setup_block (&all, parm, &data);
-      else if (data.passed_pointer || use_register_for_decl (parm))
+      else if (data.arg.pass_by_reference || use_register_for_decl (parm))
 	assign_parm_setup_reg (&all, parm, &data);
       else
 	assign_parm_setup_stack (&all, parm, &data);
@@ -3855,7 +3853,7 @@ gimplify_parameters (gimple_seq *cleanup)
 	  gimplify_one_sizepos (&DECL_SIZE_UNIT (parm), &stmts);
 	}
 
-      if (data.passed_pointer)
+      if (data.arg.pass_by_reference)
 	{
 	  tree type = TREE_TYPE (data.arg.type);
 	  function_arg_info orig_arg (type, data.arg.named);