calls.c

早期freebsd实现

	  end_sequence ();

	  /* PARTIAL referred only to the first register, so clear it for the
	     next time.  */
	  partial = 0;
	}
    }

  /* Perform postincrements before actually calling the function.  */
  emit_queue ();

  /* All arguments and registers used for the call must be set up by now!  */

  funexp = prepare_call_address (funexp, fndecl, &use_insns);

  /* Generate the actual call instruction.  */
  emit_call_1 (funexp, funtype, args_size.constant, struct_value_size,
	       FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1),
	       valreg, old_inhibit_defer_pop, use_insns, is_const);

  /* If call is cse'able, make appropriate pair of reg-notes around it.
     Test valreg so we don't crash; may safely ignore `const'
     if return type is void.  */
  if (is_const && valreg != 0)
    {
      rtx note = 0;
      rtx temp = gen_reg_rtx (GET_MODE (valreg));
      rtx insns;

      /* Construct an "equal form" for the value which mentions all the
	 arguments in order as well as the function name.  */
#ifdef PUSH_ARGS_REVERSED
      for (i = 0; i < num_actuals; i++)
	note = gen_rtx (EXPR_LIST, VOIDmode, args[i].initial_value, note);
#else
      for (i = num_actuals - 1; i >= 0; i--)
	note = gen_rtx (EXPR_LIST, VOIDmode, args[i].initial_value, note);
#endif
      note = gen_rtx (EXPR_LIST, VOIDmode, funexp, note);

      insns = get_insns ();
      end_sequence ();

      emit_libcall_block (insns, temp, valreg, note);

      valreg = temp;
    }

  /* For calls to `setjmp', etc., inform flow.c it should complain
     if nonvolatile values are live.  */

  if (returns_twice)
    {
      emit_note (name, NOTE_INSN_SETJMP);
      current_function_calls_setjmp = 1;
    }

  if (is_longjmp)
    current_function_calls_longjmp = 1;

  /* Notice functions that cannot return.
     If optimizing, insns emitted below will be dead.
     If not optimizing, they will exist, which is useful
     if the user uses the `return' command in the debugger.  */

  if (is_volatile || is_longjmp)
    emit_barrier ();

  /* If value type not void, return an rtx for the value.  */

  /* If there are cleanups to be called, don't use a hard reg as target.  */
  if (cleanups_this_call != old_cleanups
      && target && REG_P (target)
      && REGNO (target) < FIRST_PSEUDO_REGISTER)
    target = 0;

  if (TYPE_MODE (TREE_TYPE (exp)) == VOIDmode
      || ignore)
    {
      target = const0_rtx;
    }
  else if (structure_value_addr)
    {
      if (target == 0 || GET_CODE (target) != MEM)
	{
	  target = gen_rtx (MEM, TYPE_MODE (TREE_TYPE (exp)),
			    memory_address (TYPE_MODE (TREE_TYPE (exp)),
					    structure_value_addr));
	  MEM_IN_STRUCT_P (target)
	    = (TREE_CODE (TREE_TYPE (exp)) == ARRAY_TYPE
	       || TREE_CODE (TREE_TYPE (exp)) == RECORD_TYPE
	       || TREE_CODE (TREE_TYPE (exp)) == UNION_TYPE);
	}
    }
  else if (pcc_struct_value)
    {
      if (target == 0)
	{
	  target = gen_rtx (MEM, TYPE_MODE (TREE_TYPE (exp)),
			    copy_to_reg (valreg));
	  MEM_IN_STRUCT_P (target)
	    = (TREE_CODE (TREE_TYPE (exp)) == ARRAY_TYPE
	       || TREE_CODE (TREE_TYPE (exp)) == RECORD_TYPE
	       || TREE_CODE (TREE_TYPE (exp)) == UNION_TYPE);
	}
      else if (TYPE_MODE (TREE_TYPE (exp)) != BLKmode)
	emit_move_insn (target, gen_rtx (MEM, TYPE_MODE (TREE_TYPE (exp)),
					 copy_to_reg (valreg)));
      else
	emit_block_move (target, gen_rtx (MEM, BLKmode, copy_to_reg (valreg)),
			 expr_size (exp),
			 TYPE_ALIGN (TREE_TYPE (exp)) / BITS_PER_UNIT);
    }
  else if (target && GET_MODE (target) == TYPE_MODE (TREE_TYPE (exp))
	   && GET_MODE (target) == GET_MODE (valreg))
    /* TARGET and VALREG cannot be equal at this point because the latter
       would not have REG_FUNCTION_VALUE_P true, while the former would if
       it were referring to the same register.

       If they refer to the same register, this move will be a no-op, except
       when function inlining is being done.  */
    emit_move_insn (target, valreg);
  else
    target = copy_to_reg (valreg);

#ifdef PROMOTE_FUNCTION_RETURN
  /* If we promoted this return value, make the proper SUBREG.  */
  if (GET_MODE (target) != TYPE_MODE (TREE_TYPE (exp)))
    {
      enum machine_mode mode = GET_MODE (target);
      int unsignedp = TREE_UNSIGNED (TREE_TYPE (exp));

      if (TREE_CODE (TREE_TYPE (exp)) == INTEGER_TYPE
	  || TREE_CODE (TREE_TYPE (exp)) == ENUMERAL_TYPE
	  || TREE_CODE (TREE_TYPE (exp)) == BOOLEAN_TYPE
	  || TREE_CODE (TREE_TYPE (exp)) == CHAR_TYPE
	  || TREE_CODE (TREE_TYPE (exp)) == REAL_TYPE
	  || TREE_CODE (TREE_TYPE (exp)) == POINTER_TYPE
	  || TREE_CODE (TREE_TYPE (exp)) == OFFSET_TYPE)
	{
	  PROMOTE_MODE (mode, unsignedp, TREE_TYPE (exp));
	}

      target = gen_rtx (SUBREG, TYPE_MODE (TREE_TYPE (exp)), target, 0);
      SUBREG_PROMOTED_VAR_P (target) = 1;
      SUBREG_PROMOTED_UNSIGNED_P (target) = unsignedp;
    }
#endif

  /* Perform all cleanups needed for the arguments of this call
     (i.e. destructors in C++).  */
  expand_cleanups_to (old_cleanups);

  /* If size of args is variable or this was a constructor call for a stack
     argument, restore saved stack-pointer value.  */

  if (old_stack_level)
    {
      emit_stack_restore (SAVE_BLOCK, old_stack_level, NULL_RTX);
      pending_stack_adjust = old_pending_adj;
#ifdef ACCUMULATE_OUTGOING_ARGS
      stack_arg_under_construction = old_stack_arg_under_construction;
      highest_outgoing_arg_in_use = initial_highest_arg_in_use;
      stack_usage_map = initial_stack_usage_map;
#endif
    }
#ifdef ACCUMULATE_OUTGOING_ARGS
  else
    {
#ifdef REG_PARM_STACK_SPACE
      if (save_area)
	{
	  enum machine_mode save_mode = GET_MODE (save_area);
	  rtx stack_area
	    = gen_rtx (MEM, save_mode,
		       memory_address (save_mode,
#ifdef ARGS_GROW_DOWNWARD
				       plus_constant (argblock, - high_to_save)
#else
				       plus_constant (argblock, low_to_save)
#endif
				       ));

	  if (save_mode != BLKmode)
	    emit_move_insn (stack_area, save_area);
	  else
	    emit_block_move (stack_area, validize_mem (save_area),
			     GEN_INT (high_to_save - low_to_save + 1),
			     PARM_BOUNDARY / BITS_PER_UNIT);
	}
#endif
	  
      /* If we saved any argument areas, restore them.  */
      for (i = 0; i < num_actuals; i++)
	if (args[i].save_area)
	  {
	    enum machine_mode save_mode = GET_MODE (args[i].save_area);
	    rtx stack_area
	      = gen_rtx (MEM, save_mode,
			 memory_address (save_mode,
					 XEXP (args[i].stack_slot, 0)));

	    if (save_mode != BLKmode)
	      emit_move_insn (stack_area, args[i].save_area);
	    else
	      emit_block_move (stack_area, validize_mem (args[i].save_area),
			       GEN_INT (args[i].size.constant),
			       PARM_BOUNDARY / BITS_PER_UNIT);
	  }

      highest_outgoing_arg_in_use = initial_highest_arg_in_use;
      stack_usage_map = initial_stack_usage_map;
    }
#endif

  /* If this was alloca, record the new stack level for nonlocal gotos.  
     Check for the handler slots since we might not have a save area
     for non-local gotos. */

  if (may_be_alloca && nonlocal_goto_handler_slot != 0)
    emit_stack_save (SAVE_NONLOCAL, &nonlocal_goto_stack_level, NULL_RTX);

  pop_temp_slots ();

  return target;
}

#if 0
/* Return an rtx which represents a suitable home on the stack
   given TYPE, the type of the argument looking for a home.
   This is called only for BLKmode arguments.

   SIZE is the size needed for this target.
   ARGS_ADDR is the address of the bottom of the argument block for this call.
   OFFSET describes this parameter's offset into ARGS_ADDR.  It is meaningless
   if this machine uses push insns.  */

static rtx
target_for_arg (type, size, args_addr, offset)
     tree type;
     rtx size;
     rtx args_addr;
     struct args_size offset;
{
  rtx target;
  rtx offset_rtx = ARGS_SIZE_RTX (offset);

  /* We do not call memory_address if possible,
     because we want to address as close to the stack
     as possible.  For non-variable sized arguments,
     this will be stack-pointer relative addressing.  */
  if (GET_CODE (offset_rtx) == CONST_INT)
    target = plus_constant (args_addr, INTVAL (offset_rtx));
  else
    {
      /* I have no idea how to guarantee that this
	 will work in the presence of register parameters.  */
      target = gen_rtx (PLUS, Pmode, args_addr, offset_rtx);
      target = memory_address (QImode, target);
    }

  return gen_rtx (MEM, BLKmode, target);
}
#endif

/* Store a single argument for a function call
   into the register or memory area where it must be passed.
   *ARG describes the argument value and where to pass it.

   ARGBLOCK is the address of the stack-block for all the arguments,
   or 0 on a machine where arguments are pushed individually.

   MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
   so must be careful about how the stack is used. 

   VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
   argument stack.  This is used if ACCUMULATE_OUTGOING_ARGS to indicate
   that we need not worry about saving and restoring the stack.

   FNDECL is the declaration of the function we are calling.  */

static void
store_one_arg (arg, argblock, may_be_alloca, variable_size, fndecl,
	       reg_parm_stack_space)
     struct arg_data *arg;
     rtx argblock;
     int may_be_alloca;
     int variable_size;
     tree fndecl;
     int reg_parm_stack_space;
{
  register tree pval = arg->tree_value;
  rtx reg = 0;
  int partial = 0;
  int used = 0;
  int i, lower_bound, upper_bound;

  if (TREE_CODE (pval) == ERROR_MARK)
    return;

#ifdef ACCUMULATE_OUTGOING_ARGS
  /* If this is being stored into a pre-allocated, fixed-size, stack area,
     save any previous data at that location.  */
  if (argblock && ! variable_size && arg->stack)
    {
#ifdef ARGS_GROW_DOWNWARD
      /* stack_slot is negative, but we want to index stack_usage_map */
      /* with positive values. */
      if (GET_CODE (XEXP (arg->stack_slot, 0)) == PLUS)
	upper_bound = -INTVAL (XEXP (XEXP (arg->stack_slot, 0), 1)) + 1;
      else
	abort ();

      lower_bound = upper_bound - arg->size.constant;
#else
      if (GET_CODE (XEXP (arg->stack_slot, 0)) == PLUS)
	lower_bound = INTVAL (XEXP (XEXP (arg->stack_slot, 0), 1));
      else
	lower_bound = 0;

      upper_bound = lower_bound + arg->size.constant;
#endif

      for (i = lower_bound; i < upper_bound; i++)
	if (stack_usage_map[i]
#ifdef REG_PARM_STACK_SPACE
	    /* Don't store things in the fixed argument area at this point;
	       it has already been saved.  */
	    && i > reg_parm_stack_space
#endif
	    )
	  break;

      if (i != upper_bound)
	{
	  /* We need to make a save area.  See what mode we can make it.  */
	  enum machine_mode save_mode
	    = mode_for_size (arg->size.constant * BITS_PER_UNIT, MODE_INT, 1);
	  rtx stack_area
	    = gen_rtx (MEM, save_mode,
		       memory_address (save_mode, XEXP (arg->stack_slot, 0)));

	  if (save_mode == BLKmode)
	    {
	      arg->save_area = assign_stack_temp (BLKmode,
						  arg->size.constant, 1);
	      emit_block_move (validize_mem (arg->save_area), stack_area,
			       GEN_INT (arg->size.constant),
			       PARM_BOUNDARY / BITS_PER_UNIT);
	    }
	  else
	    {
	      arg->save_area = gen_reg_rtx (save_mode);
	      emit_move_insn (arg->save_area, stack_area);
	    }
	}
    }
#endif

  /* If this isn't going to be placed on both the stack and in registers,
     set up the register and number of words.  */
  if (! arg->pass_on_stack)
    reg = arg->reg, partial = arg->partial;

  if (reg != 0 && partial == 0)
    /* Being passed entirely in a register.  We shouldn't be called in
       this case.   */
    abort ();

  /* If this is being partially passed in a register, but multiple locations
     are specified, we assume that the one partially used is the one that is
     listed first.  */
  if (reg && GET_CODE (reg) == EXPR_LIST)
    reg = XEXP (reg, 0);

  /* If this is being passes partially in a register, we can't evaluate
     it directly into its stack slot.  Otherwise, we can.  */
  if (arg->value == 0)
    {
#ifdef ACCUMULATE_OUTGOING_ARGS
      /* stack_arg_under_construction is nonzero if a function argument is
	 being evaluated directly into the outgoing argument list and
	 expand_call must take special action to preserve the argument list
	 if it is called recursively.

	 For scalar function arguments stack_usage_map is sufficient to
	 determine which stack slots must be saved and restored.  Scalar
	 arguments in general have pass_on_stack == 0.

	 If this argument is initialized by a function which takes the
	 address of the argument (a C++ constructor or a C function
	 returning a BLKmode structure), then stack_usage_map is
	 insufficient and expand_call must push the stack around the
	 function call.  Such arguments have pass_on_stack == 1.

	 Note that it is always sa