gcc/cp/optimize.c

   1 /* Perform optimizations on tree structure.
   2    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2005, 2007, 2008, 2009
   3    Free Software Foundation, Inc.
   4    Written by Mark Michell (mark@codesourcery.com).
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it
   9 under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "cp-tree.h"
  28 #include "rtl.h"
  29 #include "insn-config.h"
  30 #include "input.h"
  31 #include "integrate.h"
  32 #include "toplev.h"
  33 #include "varray.h"
  34 #include "params.h"
  35 #include "hashtab.h"
  36 #include "target.h"
  37 #include "debug.h"
  38 #include "tree-inline.h"
  39 #include "flags.h"
  40 #include "langhooks.h"
  41 #include "diagnostic.h"
  42 #include "tree-dump.h"
  43 #include "gimple.h"
  44 #include "tree-iterator.h"
  45
  46 /* Prototypes.  */
  47
  48 static void update_cloned_parm (tree, tree, bool);
  49
  50 /* CLONED_PARM is a copy of CLONE, generated for a cloned constructor
  51    or destructor.  Update it to ensure that the source-position for
  52    the cloned parameter matches that for the original, and that the
  53    debugging generation code will be able to find the original PARM.  */
  54
  55 static void
  56 update_cloned_parm (tree parm, tree cloned_parm, bool first)
  57 {
  58   DECL_ABSTRACT_ORIGIN (cloned_parm) = parm;
  59
  60   /* We may have taken its address.  */
  61   TREE_ADDRESSABLE (cloned_parm) = TREE_ADDRESSABLE (parm);
  62
  63   /* The definition might have different constness.  */
  64   TREE_READONLY (cloned_parm) = TREE_READONLY (parm);
  65
  66   TREE_USED (cloned_parm) = !first || TREE_USED (parm);
  67
  68   /* The name may have changed from the declaration.  */
  69   DECL_NAME (cloned_parm) = DECL_NAME (parm);
  70   DECL_SOURCE_LOCATION (cloned_parm) = DECL_SOURCE_LOCATION (parm);
  71   TREE_TYPE (cloned_parm) = TREE_TYPE (parm);
  72
  73   DECL_GIMPLE_REG_P (cloned_parm) = DECL_GIMPLE_REG_P (parm);
  74 }
  75
  76
  77 /* FN is a function in High GIMPLE form that has a complete body and no
  78    CFG.  CLONE is a function whose body is to be set to a copy of FN,
  79    mapping argument declarations according to the ARG_MAP splay_tree.  */
  80
  81 static void
  82 clone_body (tree clone, tree fn, void *arg_map)
  83 {
  84   copy_body_data id;
  85   tree stmts;
  86
  87   /* Clone the body, as if we were making an inline call.  But, remap
  88      the parameters in the callee to the parameters of caller.  */
  89   memset (&id, 0, sizeof (id));
  90   id.src_fn = fn;
  91   id.dst_fn = clone;
  92   id.src_cfun = DECL_STRUCT_FUNCTION (fn);
  93   id.decl_map = (struct pointer_map_t *) arg_map;
  94
  95   id.copy_decl = copy_decl_no_change;
  96   id.transform_call_graph_edges = CB_CGE_DUPLICATE;
  97   id.transform_new_cfg = true;
  98   id.transform_return_to_modify = false;
  99   id.transform_lang_insert_block = NULL;
 100
 101   /* We're not inside any EH region.  */
 102   id.eh_region = -1;
 103
 104   stmts = DECL_SAVED_TREE (fn);
 105   walk_tree (&stmts, copy_tree_body_r, &id, NULL);
 106   append_to_statement_list_force (stmts, &DECL_SAVED_TREE (clone));
 107 }
 108
 109 /* DELETE_DTOR is a delete destructor whose body will be built.
 110    COMPLETE_DTOR is the corresponding complete destructor.  */
 111
 112 static void
 113 build_delete_destructor_body (tree delete_dtor, tree complete_dtor)
 114 {
 115   tree call_dtor, call_delete;
 116   tree parm = DECL_ARGUMENTS (delete_dtor);
 117   tree virtual_size = cxx_sizeof (current_class_type);
 118
 119   /* Call the corresponding complete destructor.  */
 120   gcc_assert (complete_dtor);
 121   call_dtor = build_cxx_call (complete_dtor, 1, &parm);
 122   add_stmt (call_dtor);
 123
 124   add_stmt (build_stmt (0, LABEL_EXPR, cdtor_label));
 125
 126   /* Call the delete function.  */
 127   call_delete = build_op_delete_call (DELETE_EXPR, current_class_ptr,
 128                                       virtual_size,
 129                                       /*global_p=*/false,
 130                                       /*placement=*/NULL_TREE,
 131                                       /*alloc_fn=*/NULL_TREE);
 132   add_stmt (call_delete);
 133
 134   /* Return the address of the object.  */
 135   if (targetm.cxx.cdtor_returns_this ())
 136     {
 137       tree val = DECL_ARGUMENTS (delete_dtor);
 138       val = build2 (MODIFY_EXPR, TREE_TYPE (val),
 139                     DECL_RESULT (delete_dtor), val);
 140       add_stmt (build_stmt (0, RETURN_EXPR, val));
 141     }
 142 }
 143
 144 /* FN is a function that has a complete body.  Clone the body as
 145    necessary.  Returns nonzero if there's no longer any need to
 146    process the main body.  */
 147
 148 bool
 149 maybe_clone_body (tree fn)
 150 {
 151   tree clone;
 152   tree complete_dtor = NULL_TREE;
 153   bool first = true;
 154
 155   /* We only clone constructors and destructors.  */
 156   if (!DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (fn)
 157       && !DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (fn))
 158     return 0;
 159
 160   /* Emit the DWARF1 abstract instance.  */
 161   (*debug_hooks->deferred_inline_function) (fn);
 162
 163   /* Look for the complete destructor which may be used to build the
 164      delete destructor.  */
 165   FOR_EACH_CLONE (clone, fn)
 166     if (DECL_NAME (clone) == complete_dtor_identifier)
 167       {
 168         complete_dtor = clone;
 169         break;
 170       }
 171
 172   /* We know that any clones immediately follow FN in the TYPE_METHODS
 173      list.  */
 174   push_to_top_level ();
 175   FOR_EACH_CLONE (clone, fn)
 176     {
 177       tree parm;
 178       tree clone_parm;
 179       int parmno;
 180       struct pointer_map_t *decl_map;
 181
 182       /* Update CLONE's source position information to match FN's.  */
 183       DECL_SOURCE_LOCATION (clone) = DECL_SOURCE_LOCATION (fn);
 184       DECL_DECLARED_INLINE_P (clone) = DECL_DECLARED_INLINE_P (fn);
 185       DECL_COMDAT (clone) = DECL_COMDAT (fn);
 186       DECL_WEAK (clone) = DECL_WEAK (fn);
 187
 188       /* We don't copy the comdat group from fn to clone because the assembler
 189          name of fn was corrupted by write_mangled_name by adding *INTERNAL*
 190          to it. By doing so, it also corrupted the comdat group. */
 191       if (DECL_ONE_ONLY (fn))
 192         DECL_COMDAT_GROUP (clone) = cxx_comdat_group (clone);
 193       DECL_SECTION_NAME (clone) = DECL_SECTION_NAME (fn);
 194       DECL_USE_TEMPLATE (clone) = DECL_USE_TEMPLATE (fn);
 195       DECL_EXTERNAL (clone) = DECL_EXTERNAL (fn);
 196       DECL_INTERFACE_KNOWN (clone) = DECL_INTERFACE_KNOWN (fn);
 197       DECL_NOT_REALLY_EXTERN (clone) = DECL_NOT_REALLY_EXTERN (fn);
 198       TREE_PUBLIC (clone) = TREE_PUBLIC (fn);
 199       DECL_VISIBILITY (clone) = DECL_VISIBILITY (fn);
 200       DECL_VISIBILITY_SPECIFIED (clone) = DECL_VISIBILITY_SPECIFIED (fn);
 201       DECL_DLLIMPORT_P (clone) = DECL_DLLIMPORT_P (fn);
 202
 203       /* Adjust the parameter names and locations.  */
 204       parm = DECL_ARGUMENTS (fn);
 205       clone_parm = DECL_ARGUMENTS (clone);
 206       /* Update the `this' parameter, which is always first.  */
 207       update_cloned_parm (parm, clone_parm, first);
 208       parm = TREE_CHAIN (parm);
 209       clone_parm = TREE_CHAIN (clone_parm);
 210       if (DECL_HAS_IN_CHARGE_PARM_P (fn))
 211         parm = TREE_CHAIN (parm);
 212       if (DECL_HAS_VTT_PARM_P (fn))
 213         parm = TREE_CHAIN (parm);
 214       if (DECL_HAS_VTT_PARM_P (clone))
 215         clone_parm = TREE_CHAIN (clone_parm);
 216       for (; parm;
 217            parm = TREE_CHAIN (parm), clone_parm = TREE_CHAIN (clone_parm))
 218         /* Update this parameter.  */
 219         update_cloned_parm (parm, clone_parm, first);
 220
 221       /* Start processing the function.  */
 222       start_preparsed_function (clone, NULL_TREE, SF_PRE_PARSED);
 223
 224       /* Build the delete destructor by calling complete destructor
 225          and delete function.  */
 226       if (DECL_NAME (clone) == deleting_dtor_identifier)
 227         build_delete_destructor_body (clone, complete_dtor);
 228       else
 229         {
 230           /* Remap the parameters.  */
 231           decl_map = pointer_map_create ();
 232           for (parmno = 0,
 233                 parm = DECL_ARGUMENTS (fn),
 234                 clone_parm = DECL_ARGUMENTS (clone);
 235               parm;
 236               ++parmno,
 237                 parm = TREE_CHAIN (parm))
 238             {
 239               /* Map the in-charge parameter to an appropriate constant.  */
 240               if (DECL_HAS_IN_CHARGE_PARM_P (fn) && parmno == 1)
 241                 {
 242                   tree in_charge;
 243                   in_charge = in_charge_arg_for_name (DECL_NAME (clone));
 244                   *pointer_map_insert (decl_map, parm) = in_charge;
 245                 }
 246               else if (DECL_ARTIFICIAL (parm)
 247                        && DECL_NAME (parm) == vtt_parm_identifier)
 248                 {
 249                   /* For a subobject constructor or destructor, the next
 250                      argument is the VTT parameter.  Remap the VTT_PARM
 251                      from the CLONE to this parameter.  */
 252                   if (DECL_HAS_VTT_PARM_P (clone))
 253                     {
 254                       DECL_ABSTRACT_ORIGIN (clone_parm) = parm;
 255                       *pointer_map_insert (decl_map, parm) = clone_parm;
 256                       clone_parm = TREE_CHAIN (clone_parm);
 257                     }
 258                   /* Otherwise, map the VTT parameter to `NULL'.  */
 259                   else
 260                     *pointer_map_insert (decl_map, parm)
 261                        = fold_convert (TREE_TYPE (parm), null_pointer_node);
 262                 }
 263               /* Map other parameters to their equivalents in the cloned
 264                  function.  */
 265               else
 266                 {
 267                   *pointer_map_insert (decl_map, parm) = clone_parm;
 268                   clone_parm = TREE_CHAIN (clone_parm);
 269                 }
 270             }
 271
 272           if (targetm.cxx.cdtor_returns_this ())
 273             {
 274               parm = DECL_RESULT (fn);
 275               clone_parm = DECL_RESULT (clone);
 276               *pointer_map_insert (decl_map, parm) = clone_parm;
 277             }
 278
 279           /* Clone the body.  */
 280           clone_body (clone, fn, decl_map);
 281
 282           /* Clean up.  */
 283           pointer_map_destroy (decl_map);
 284         }
 285
 286       /* The clone can throw iff the original function can throw.  */
 287       cp_function_chain->can_throw = !TREE_NOTHROW (fn);
 288
 289       /* Now, expand this function into RTL, if appropriate.  */
 290       finish_function (0);
 291       BLOCK_ABSTRACT_ORIGIN (DECL_INITIAL (clone)) = DECL_INITIAL (fn);
 292       expand_or_defer_fn (clone);
 293       first = false;
 294     }
 295   pop_from_top_level ();
 296
 297   /* We don't need to process the original function any further.  */
 298   return 1;
 299 }