gcc/cgraphbuild.c

   1 /* Callgraph construction.
   2    Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
   3    Contributed by Jan Hubicka
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "tree-flow.h"
  28 #include "langhooks.h"
  29 #include "pointer-set.h"
  30 #include "cgraph.h"
  31 #include "intl.h"
  32 #include "tree-gimple.h"
  33 #include "tree-pass.h"
  34
  35 /* Walk tree and record all calls and references to functions/variables.
  36    Called via walk_tree: TP is pointer to tree to be examined.  */
  37
  38 static tree
  39 record_reference (tree *tp, int *walk_subtrees, void *data)
  40 {
  41   tree t = *tp;
  42
  43   switch (TREE_CODE (t))
  44     {
  45     case VAR_DECL:
  46       if (TREE_STATIC (t) || DECL_EXTERNAL (t))
  47         {
  48           varpool_mark_needed_node (varpool_node (t));
  49           if (lang_hooks.callgraph.analyze_expr)
  50             return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees,
  51                                                       data);
  52         }
  53       break;
  54
  55     case FDESC_EXPR:
  56     case ADDR_EXPR:
  57       if (flag_unit_at_a_time)
  58         {
  59           /* Record dereferences to the functions.  This makes the
  60              functions reachable unconditionally.  */
  61           tree decl = TREE_OPERAND (*tp, 0);
  62           if (TREE_CODE (decl) == FUNCTION_DECL)
  63             cgraph_mark_needed_node (cgraph_node (decl));
  64         }
  65       break;
  66
  67     default:
  68       /* Save some cycles by not walking types and declaration as we
  69          won't find anything useful there anyway.  */
  70       if (IS_TYPE_OR_DECL_P (*tp))
  71         {
  72           *walk_subtrees = 0;
  73           break;
  74         }
  75
  76       if ((unsigned int) TREE_CODE (t) >= LAST_AND_UNUSED_TREE_CODE)
  77         return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees, data);
  78       break;
  79     }
  80
  81   return NULL_TREE;
  82 }
  83
  84 /* Give initial reasons why inlining would fail on all calls from
  85    NODE.  Those get either nullified or usually overwritten by more precise
  86    reason later.  */
  87
  88 static void
  89 initialize_inline_failed (struct cgraph_node *node)
  90 {
  91   struct cgraph_edge *e;
  92
  93   for (e = node->callers; e; e = e->next_caller)
  94     {
  95       gcc_assert (!e->callee->global.inlined_to);
  96       gcc_assert (e->inline_failed);
  97       if (node->local.redefined_extern_inline)
  98         e->inline_failed = N_("redefined extern inline functions are not "
  99                            "considered for inlining");
 100       else if (!node->local.inlinable)
 101         e->inline_failed = N_("function not inlinable");
 102       else
 103         e->inline_failed = N_("function not considered for inlining");
 104     }
 105 }
 106
 107 /* Create cgraph edges for function calls.
 108    Also look for functions and variables having addresses taken.  */
 109
 110 static unsigned int
 111 build_cgraph_edges (void)
 112 {
 113   basic_block bb;
 114   struct cgraph_node *node = cgraph_node (current_function_decl);
 115   struct pointer_set_t *visited_nodes = pointer_set_create ();
 116   block_stmt_iterator bsi;
 117   tree step;
 118   int entry_freq = ENTRY_BLOCK_PTR->frequency;
 119
 120   if (!entry_freq)
 121     entry_freq = 1;
 122
 123   /* Create the callgraph edges and record the nodes referenced by the function.
 124      body.  */
 125   FOR_EACH_BB (bb)
 126     for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
 127       {
 128         tree stmt = bsi_stmt (bsi);
 129         tree call = get_call_expr_in (stmt);
 130         tree decl;
 131
 132         if (call && (decl = get_callee_fndecl (call)))
 133           {
 134             int freq = (!bb->frequency && !entry_freq ? CGRAPH_FREQ_BASE
 135                         : bb->frequency * CGRAPH_FREQ_BASE / entry_freq);
 136             if (freq > CGRAPH_FREQ_MAX)
 137               freq = CGRAPH_FREQ_MAX;
 138             cgraph_create_edge (node, cgraph_node (decl), stmt,
 139                                 bb->count, freq,
 140                                 bb->loop_depth);
 141             walk_tree (&TREE_OPERAND (call, 1),
 142                        record_reference, node, visited_nodes);
 143             if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
 144               walk_tree (&GIMPLE_STMT_OPERAND (stmt, 0),
 145                          record_reference, node, visited_nodes);
 146           }
 147         else
 148           walk_tree (bsi_stmt_ptr (bsi), record_reference, node, visited_nodes);
 149       }
 150
 151   /* Look for initializers of constant variables and private statics.  */
 152   for (step = cfun->unexpanded_var_list;
 153        step;
 154        step = TREE_CHAIN (step))
 155     {
 156       tree decl = TREE_VALUE (step);
 157       if (TREE_CODE (decl) == VAR_DECL
 158           && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 159           && flag_unit_at_a_time)
 160         varpool_finalize_decl (decl);
 161       else if (TREE_CODE (decl) == VAR_DECL && DECL_INITIAL (decl))
 162         walk_tree (&DECL_INITIAL (decl), record_reference, node, visited_nodes);
 163     }
 164
 165   pointer_set_destroy (visited_nodes);
 166   initialize_inline_failed (node);
 167   return 0;
 168 }
 169
 170 struct tree_opt_pass pass_build_cgraph_edges =
 171 {
 172   NULL,                                 /* name */
 173   NULL,                                 /* gate */
 174   build_cgraph_edges,                   /* execute */
 175   NULL,                                 /* sub */
 176   NULL,                                 /* next */
 177   0,                                    /* static_pass_number */
 178   0,                                    /* tv_id */
 179   PROP_cfg,                             /* properties_required */
 180   0,                                    /* properties_provided */
 181   0,                                    /* properties_destroyed */
 182   0,                                    /* todo_flags_start */
 183   0,                                    /* todo_flags_finish */
 184   0                                     /* letter */
 185 };
 186
 187 /* Record references to functions and other variables present in the
 188    initial value of DECL, a variable.  */
 189
 190 void
 191 record_references_in_initializer (tree decl)
 192 {
 193   struct pointer_set_t *visited_nodes = pointer_set_create ();
 194   walk_tree (&DECL_INITIAL (decl), record_reference, NULL, visited_nodes);
 195   pointer_set_destroy (visited_nodes);
 196 }
 197
 198 /* Rebuild cgraph edges for current function node.  This needs to be run after
 199    passes that don't update the cgraph.  */
 200
 201 static unsigned int
 202 rebuild_cgraph_edges (void)
 203 {
 204   basic_block bb;
 205   struct cgraph_node *node = cgraph_node (current_function_decl);
 206   block_stmt_iterator bsi;
 207   int entry_freq = ENTRY_BLOCK_PTR->frequency;
 208
 209   if (!entry_freq)
 210     entry_freq = 1;
 211
 212   cgraph_node_remove_callees (node);
 213
 214   node->count = ENTRY_BLOCK_PTR->count;
 215
 216   FOR_EACH_BB (bb)
 217     for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
 218       {
 219         tree stmt = bsi_stmt (bsi);
 220         tree call = get_call_expr_in (stmt);
 221         tree decl;
 222
 223         if (call && (decl = get_callee_fndecl (call)))
 224           {
 225             int freq = (!bb->frequency && !entry_freq ? CGRAPH_FREQ_BASE
 226                         : bb->frequency * CGRAPH_FREQ_BASE / entry_freq);
 227             if (freq > CGRAPH_FREQ_MAX)
 228               freq = CGRAPH_FREQ_MAX;
 229             cgraph_create_edge (node, cgraph_node (decl), stmt,
 230                                 bb->count, freq, bb->loop_depth);
 231            }
 232       }
 233   initialize_inline_failed (node);
 234   gcc_assert (!node->global.inlined_to);
 235   return 0;
 236 }
 237
 238 struct tree_opt_pass pass_rebuild_cgraph_edges =
 239 {
 240   NULL,                                 /* name */
 241   NULL,                                 /* gate */
 242   rebuild_cgraph_edges,                 /* execute */
 243   NULL,                                 /* sub */
 244   NULL,                                 /* next */
 245   0,                                    /* static_pass_number */
 246   0,                                    /* tv_id */
 247   PROP_cfg,                             /* properties_required */
 248   0,                                    /* properties_provided */
 249   0,                                    /* properties_destroyed */
 250   0,                                    /* todo_flags_start */
 251   0,                                    /* todo_flags_finish */
 252   0                                     /* letter */
 253 };