expr.c revision 132718 
1/* Convert language-specific tree expression to rtl instructions,
2   for GNU compiler.
3   Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
4   2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5
6This file is part of GCC.
7
8GCC is free software; you can redistribute it and/or modify
9it under the terms of the GNU General Public License as published by
10the Free Software Foundation; either version 2, or (at your option)
11any later version.
12
13GCC is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16GNU General Public License for more details.
17
18You should have received a copy of the GNU General Public License
19along with GCC; see the file COPYING.  If not, write to
20the Free Software Foundation, 59 Temple Place - Suite 330,
21Boston, MA 02111-1307, USA.  */
22
23
24#include "config.h"
25#include "system.h"
26#include "coretypes.h"
27#include "tm.h"
28#include "rtl.h"
29#include "tree.h"
30#include "flags.h"
31#include "expr.h"
32#include "cp-tree.h"
33#include "toplev.h"
34#include "except.h"
35#include "tm_p.h"
36
37/* Hook used by output_constant to expand language-specific
38   constants.  */
39
40tree
41cplus_expand_constant (tree cst)
42{
43  switch (TREE_CODE (cst))
44    {
45    case PTRMEM_CST:
46      {
47	tree type = TREE_TYPE (cst);
48	tree member;
49
50	/* Find the member.  */
51	member = PTRMEM_CST_MEMBER (cst);
52
53	if (TREE_CODE (member) == FIELD_DECL)
54	  {
55	    /* Find the offset for the field.  */
56	    cst = byte_position (member);
57	    while (!same_type_p (DECL_CONTEXT (member),
58				 TYPE_PTRMEM_CLASS_TYPE (type)))
59	      {
60		/* The MEMBER must have been nestled within an
61		   anonymous aggregate contained in TYPE.  Find the
62		   anonymous aggregate.  */
63		member = lookup_anon_field (TYPE_PTRMEM_CLASS_TYPE (type),
64					    DECL_CONTEXT (member));
65		cst = size_binop (PLUS_EXPR, cst, byte_position (member));
66	      }
67	    cst = fold (build_nop (type, cst));
68	  }
69	else
70	  {
71	    tree delta;
72	    tree pfn;
73
74	    expand_ptrmemfunc_cst (cst, &delta, &pfn);
75	    cst = build_ptrmemfunc1 (type, delta, pfn);
76	  }
77      }
78      break;
79
80    default:
81      /* There's nothing to do.  */
82      break;
83    }
84
85  return cst;
86}
87
88/* Hook used by expand_expr to expand language-specific tree codes.  */
89
90rtx
91cxx_expand_expr (tree exp, rtx target, enum machine_mode tmode, int modifier,
92		 rtx *alt_rtl)
93{
94  tree type = TREE_TYPE (exp);
95  enum machine_mode mode = TYPE_MODE (type);
96  enum tree_code code = TREE_CODE (exp);
97  rtx ret;
98
99  /* No sense saving up arithmetic to be done
100     if it's all in the wrong mode to form part of an address.
101     And force_operand won't know whether to sign-extend or zero-extend.  */
102
103  if (mode != Pmode && modifier == EXPAND_SUM)
104    modifier = EXPAND_NORMAL;
105
106  switch (code)
107    {
108    case PTRMEM_CST:
109      return expand_expr (cplus_expand_constant (exp),
110			  target, tmode, modifier);
111
112    case OFFSET_REF:
113      /* Offset refs should not make it through to here.  */
114      abort ();
115      return const0_rtx;
116
117    case THROW_EXPR:
118      expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
119      return const0_rtx;
120
121    case MUST_NOT_THROW_EXPR:
122      expand_eh_region_start ();
123      ret = expand_expr (TREE_OPERAND (exp, 0), target, tmode, modifier);
124      expand_eh_region_end_must_not_throw (build_call (terminate_node, 0));
125      return ret;
126
127    case EMPTY_CLASS_EXPR:
128      /* We don't need to generate any code for an empty class.  */
129      return const0_rtx;
130
131    case BASELINK:
132      return expand_expr (BASELINK_FUNCTIONS (exp), target, tmode,
133			  modifier);
134
135    default:
136      return c_expand_expr (exp, target, tmode, modifier, alt_rtl);
137    }
138  abort ();
139  /* NOTREACHED */
140  return NULL;
141}
142