/* Convert language-specific tree expression to rtl instructions,
   for GNU compiler.
   Copyright (C) 1988, 1992, 1993 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#ifndef lint
static char rcsid[] = "$Id: cp-expr.c,v 1.2 1993/08/02 17:31:45 mycroft Exp $";
#endif /* not lint */

#include "config.h"
#include "rtl.h"
#include "tree.h"
#include "flags.h"
#include "expr.h"
#include "cp-tree.h"

#undef NULL
#define NULL 0

/* Hook used by expand_expr to expand language-specific tree codes.  */

rtx
cplus_expand_expr (exp, target, tmode, modifier)
     tree exp;
     rtx target;
     enum machine_mode tmode;
     enum expand_modifier modifier;
{
  tree type = TREE_TYPE (exp);
  register enum machine_mode mode = TYPE_MODE (type);
  register enum tree_code code = TREE_CODE (exp);
  rtx original_target = target;
  int ignore = target == const0_rtx;

  if (ignore) target = 0, original_target = 0;

  /* No sense saving up arithmetic to be done
     if it's all in the wrong mode to form part of an address.
     And force_operand won't know whether to sign-extend or zero-extend.  */

  if (mode != Pmode && modifier == EXPAND_SUM)
    modifier = EXPAND_NORMAL;

  switch (code)
    {
    case NEW_EXPR:
      {
	/* Something needs to be initialized, but we didn't know
	   where that thing was when building the tree.  For example,
	   it could be the return value of a function, or a parameter
	   to a function which lays down in the stack, or a temporary
	   variable which must be passed by reference.

	   Cleanups are handled in a language-specific way: they
	   might be run by the called function (true in GNU C++
	   for parameters with cleanups), or they might be
	   run by the caller, after the call (true in GNU C++
	   for other cleanup needs).  */

	tree func = TREE_OPERAND (exp, 0);
	tree args = TREE_OPERAND (exp, 1);
	tree type = TREE_TYPE (exp), slot;
	tree fn_type = TREE_TYPE (TREE_TYPE (func));
	tree return_type = TREE_TYPE (fn_type);
	rtx call_target, return_target;

	/* The expression `init' wants to initialize what
	   `target' represents.  SLOT holds the slot for TARGET.  */
	slot = TREE_OPERAND (exp, 2);

	if (target == 0)
	  {
	    /* Should always be called with a target in BLKmode case.  */
	    my_friendly_assert (mode != BLKmode, 205);
	    my_friendly_assert (DECL_RTL (slot) != 0, 206);

	    target = gen_reg_rtx (mode);
	  }

	/* The target the initializer will initialize (CALL_TARGET)
	   must now be directed to initialize the target we are
	   supposed to initialize (TARGET).  The semantics for
	   choosing what CALL_TARGET is is language-specific,
	   as is building the call which will perform the
	   initialization.  It is left here to show the choices that
	   exist for C++.  */
	   
	if (TREE_CODE (func) == ADDR_EXPR
	    && TREE_CODE (TREE_OPERAND (func, 0)) == FUNCTION_DECL
	    && DECL_CONSTRUCTOR_P (TREE_OPERAND (func, 0)))
	  {
	    type = TYPE_POINTER_TO (type);
	    /* Don't clobber a value that might be part of a default
	       parameter value.  */
	    if (TREE_PERMANENT (args))
	      args = tree_cons (0, build1 (ADDR_EXPR, type, slot),
				TREE_CHAIN (args));
	    else
	      TREE_VALUE (args) = build1 (ADDR_EXPR, type, slot);
	    call_target = 0;
	  }
	else if (TREE_CODE (return_type) == REFERENCE_TYPE)
	  {
	    type = return_type;
	    call_target = 0;
	  }
	else
	  {
	    call_target = target;
	  }
	if (call_target)
	  preserve_temp_slots (call_target);
	preserve_temp_slots (DECL_RTL (slot));
	return_target = expand_expr (build (CALL_EXPR, type, func, args, 0), call_target, mode, 0);
	free_temp_slots ();
	if (call_target == 0)
	  call_target = return_target;
	else if (call_target != return_target)
	  {
	    if (GET_MODE (return_target) == BLKmode)
	      emit_block_move (call_target, return_target, expr_size (exp),
			       TYPE_ALIGN (type) / BITS_PER_UNIT);
	    else
	      emit_move_insn (call_target, return_target);
	  }

	if (TREE_CODE (return_type) == REFERENCE_TYPE)
	  {
	    tree init;

	    if (GET_CODE (call_target) == REG
		&& REGNO (call_target) < FIRST_PSEUDO_REGISTER)
	      my_friendly_abort (39);

	    type = TREE_TYPE (exp);

	    init = build (RTL_EXPR, return_type, 0, call_target);
	    /* We got back a reference to the type we want.  Now initialize
	       target with that.  */
	    expand_aggr_init (slot, init, 0);
	  }

	if (DECL_RTL (slot) != target)
	  emit_move_insn (DECL_RTL (slot), target);
	return DECL_RTL (slot);
      }

    case OFFSET_REF:
      {
	tree base = build_unary_op (ADDR_EXPR, TREE_OPERAND (exp, 0), 0);
	tree offset = build_unary_op (ADDR_EXPR, TREE_OPERAND (exp, 1), 0);
	return expand_expr (build (PLUS_EXPR, TREE_TYPE (exp), base, offset),
			    target, tmode, EXPAND_NORMAL);
      }

    default:
      break;
    }
  my_friendly_abort (40);
  /* NOTREACHED */
  return NULL;
}

void
init_cplus_expand ()
{
  lang_expand_expr = cplus_expand_expr;
}

/* If DECL had its rtl moved from where callers expect it
   to be, fix it up.  RESULT is the nominal rtl for the RESULT_DECL,
   which may be a pseudo instead of a hard register.  */

void
fixup_result_decl (decl, result)
     tree decl;
     rtx result;
{
  if (REG_P (result))
    {
      if (REGNO (result) >= FIRST_PSEUDO_REGISTER)
	{
	  rtx real_decl_result;

#ifdef FUNCTION_OUTGOING_VALUE
	  real_decl_result
	    = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl), current_function_decl);
#else
	  real_decl_result
	    = FUNCTION_VALUE (TREE_TYPE (decl), current_function_decl);
#endif
	  REG_FUNCTION_VALUE_P (real_decl_result) = 1;
	  result = real_decl_result;
	}
      emit_move_insn (result, DECL_RTL (decl));
      emit_insn (gen_rtx (USE, VOIDmode, result));
    }
}

/* Return nonzero iff DECL is memory-based.  The DECL_RTL of
   certain const variables might be a CONST_INT, or a REG
   in some cases.  We cannot use `memory_operand' as a test
   here because on most RISC machines, a variable's address
   is not, by itself, a legitimate address.  */
int
decl_in_memory_p (decl)
     tree decl;
{
  return DECL_RTL (decl) != 0 && GET_CODE (DECL_RTL (decl)) == MEM;
}