gcc/cgraphbuild.c

   1 /* Callgraph construction.
   2    Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009
   3    Free Software Foundation, Inc.
   4    Contributed by Jan Hubicka
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 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 "tree-flow.h"
  28 #include "langhooks.h"
  29 #include "pointer-set.h"
  30 #include "cgraph.h"
  31 #include "intl.h"
  32 #include "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 ATTRIBUTE_UNUSED)
  40 {
  41   tree t = *tp;
  42   tree decl;
  43
  44   switch (TREE_CODE (t))
  45     {
  46     case VAR_DECL:
  47       if (TREE_STATIC (t) || DECL_EXTERNAL (t))
  48         {
  49           varpool_mark_needed_node (varpool_node (t));
  50           if (lang_hooks.callgraph.analyze_expr)
  51             return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees);
  52         }
  53       break;
  54
  55     case FDESC_EXPR:
  56     case ADDR_EXPR:
  57       /* Record dereferences to the functions.  This makes the
  58          functions reachable unconditionally.  */
  59       decl = TREE_OPERAND (*tp, 0);
  60       if (TREE_CODE (decl) == FUNCTION_DECL)
  61         cgraph_mark_address_taken_node (cgraph_node (decl));
  62       break;
  63
  64     default:
  65       /* Save some cycles by not walking types and declaration as we
  66          won't find anything useful there anyway.  */
  67       if (IS_TYPE_OR_DECL_P (*tp))
  68         {
  69           *walk_subtrees = 0;
  70           break;
  71         }
  72
  73       if ((unsigned int) TREE_CODE (t) >= LAST_AND_UNUSED_TREE_CODE)
  74         return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees);
  75       break;
  76     }
  77
  78   return NULL_TREE;
  79 }
  80
  81 /* Computes the frequency of the call statement so that it can be stored in
  82    cgraph_edge.  BB is the basic block of the call statement.  */
  83 int
  84 compute_call_stmt_bb_frequency (tree decl, basic_block bb)
  85 {
  86   int entry_freq = ENTRY_BLOCK_PTR->frequency;
  87   int freq = bb->frequency;
  88
  89   if (profile_status_for_function (DECL_STRUCT_FUNCTION (decl)) == PROFILE_ABSENT)
  90     return CGRAPH_FREQ_BASE;
  91
  92   if (!entry_freq)
  93     entry_freq = 1, freq++;
  94
  95   freq = freq * CGRAPH_FREQ_BASE / entry_freq;
  96   if (freq > CGRAPH_FREQ_MAX)
  97     freq = CGRAPH_FREQ_MAX;
  98
  99   return freq;
 100 }
 101
 102 /* Create cgraph edges for function calls.
 103    Also look for functions and variables having addresses taken.  */
 104
 105 static unsigned int
 106 build_cgraph_edges (void)
 107 {
 108   basic_block bb;
 109   struct cgraph_node *node = cgraph_node (current_function_decl);
 110   struct pointer_set_t *visited_nodes = pointer_set_create ();
 111   gimple_stmt_iterator gsi;
 112   tree step;
 113
 114   /* Create the callgraph edges and record the nodes referenced by the function.
 115      body.  */
 116   FOR_EACH_BB (bb)
 117     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 118       {
 119         gimple stmt = gsi_stmt (gsi);
 120         tree decl;
 121
 122         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 123           {
 124             size_t i;
 125             size_t n = gimple_call_num_args (stmt);
 126             cgraph_create_edge (node, cgraph_node (decl), stmt,
 127                                 bb->count, compute_call_stmt_bb_frequency (current_function_decl, bb),
 128                                 bb->loop_depth);
 129             for (i = 0; i < n; i++)
 130               walk_tree (gimple_call_arg_ptr (stmt, i), record_reference,
 131                          node, visited_nodes);
 132             if (gimple_call_lhs (stmt))
 133               walk_tree (gimple_call_lhs_ptr (stmt), record_reference, node,
 134                          visited_nodes);
 135           }
 136         else
 137           {
 138             struct walk_stmt_info wi;
 139             memset (&wi, 0, sizeof (wi));
 140             wi.info = node;
 141             wi.pset = visited_nodes;
 142             walk_gimple_op (stmt, record_reference, &wi);
 143             if (gimple_code (stmt) == GIMPLE_OMP_PARALLEL
 144                 && gimple_omp_parallel_child_fn (stmt))
 145               {
 146                 tree fn = gimple_omp_parallel_child_fn (stmt);
 147                 cgraph_mark_needed_node (cgraph_node (fn));
 148               }
 149             if (gimple_code (stmt) == GIMPLE_OMP_TASK)
 150               {
 151                 tree fn = gimple_omp_task_child_fn (stmt);
 152                 if (fn)
 153                   cgraph_mark_needed_node (cgraph_node (fn));
 154                 fn = gimple_omp_task_copy_fn (stmt);
 155                 if (fn)
 156                   cgraph_mark_needed_node (cgraph_node (fn));
 157               }
 158           }
 159       }
 160
 161   /* Look for initializers of constant variables and private statics.  */
 162   for (step = cfun->local_decls;
 163        step;
 164        step = TREE_CHAIN (step))
 165     {
 166       tree decl = TREE_VALUE (step);
 167       if (TREE_CODE (decl) == VAR_DECL
 168           && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl)))
 169         varpool_finalize_decl (decl);
 170       else if (TREE_CODE (decl) == VAR_DECL && DECL_INITIAL (decl))
 171         walk_tree (&DECL_INITIAL (decl), record_reference, node, visited_nodes);
 172     }
 173
 174   pointer_set_destroy (visited_nodes);
 175   return 0;
 176 }
 177
 178 struct gimple_opt_pass pass_build_cgraph_edges =
 179 {
 180  {
 181   GIMPLE_PASS,
 182   NULL,                                 /* name */
 183   NULL,                                 /* gate */
 184   build_cgraph_edges,                   /* execute */
 185   NULL,                                 /* sub */
 186   NULL,                                 /* next */
 187   0,                                    /* static_pass_number */
 188   TV_NONE,                              /* tv_id */
 189   PROP_cfg,                             /* properties_required */
 190   0,                                    /* properties_provided */
 191   0,                                    /* properties_destroyed */
 192   0,                                    /* todo_flags_start */
 193   0                                     /* todo_flags_finish */
 194  }
 195 };
 196
 197 /* Record references to functions and other variables present in the
 198    initial value of DECL, a variable.  */
 199
 200 void
 201 record_references_in_initializer (tree decl)
 202 {
 203   struct pointer_set_t *visited_nodes = pointer_set_create ();
 204   walk_tree (&DECL_INITIAL (decl), record_reference, NULL, visited_nodes);
 205   pointer_set_destroy (visited_nodes);
 206 }
 207
 208 /* Rebuild cgraph edges for current function node.  This needs to be run after
 209    passes that don't update the cgraph.  */
 210
 211 unsigned int
 212 rebuild_cgraph_edges (void)
 213 {
 214   basic_block bb;
 215   struct cgraph_node *node = cgraph_node (current_function_decl);
 216   gimple_stmt_iterator gsi;
 217
 218   cgraph_node_remove_callees (node);
 219
 220   node->count = ENTRY_BLOCK_PTR->count;
 221
 222   FOR_EACH_BB (bb)
 223     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 224       {
 225         gimple stmt = gsi_stmt (gsi);
 226         tree decl;
 227
 228         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 229           cgraph_create_edge (node, cgraph_node (decl), stmt,
 230                               bb->count,
 231                               compute_call_stmt_bb_frequency
 232                                 (current_function_decl, bb),
 233                               bb->loop_depth);
 234
 235       }
 236   gcc_assert (!node->global.inlined_to);
 237
 238   return 0;
 239 }
 240
 241 struct gimple_opt_pass pass_rebuild_cgraph_edges =
 242 {
 243  {
 244   GIMPLE_PASS,
 245   NULL,                                 /* name */
 246   NULL,                                 /* gate */
 247   rebuild_cgraph_edges,                 /* execute */
 248   NULL,                                 /* sub */
 249   NULL,                                 /* next */
 250   0,                                    /* static_pass_number */
 251   TV_NONE,                              /* tv_id */
 252   PROP_cfg,                             /* properties_required */
 253   0,                                    /* properties_provided */
 254   0,                                    /* properties_destroyed */
 255   0,                                    /* todo_flags_start */
 256   0,                                    /* todo_flags_finish */
 257  }
 258 };
 259
 260
 261 static unsigned int
 262 remove_cgraph_callee_edges (void)
 263 {
 264   cgraph_node_remove_callees (cgraph_node (current_function_decl));
 265   return 0;
 266 }
 267
 268 struct gimple_opt_pass pass_remove_cgraph_callee_edges =
 269 {
 270  {
 271   GIMPLE_PASS,
 272   NULL,                                 /* name */
 273   NULL,                                 /* gate */
 274   remove_cgraph_callee_edges,           /* execute */
 275   NULL,                                 /* sub */
 276   NULL,                                 /* next */
 277   0,                                    /* static_pass_number */
 278   TV_NONE,                              /* tv_id */
 279   0,                                    /* properties_required */
 280   0,                                    /* properties_provided */
 281   0,                                    /* properties_destroyed */
 282   0,                                    /* todo_flags_start */
 283   0,                                    /* todo_flags_finish */
 284  }
 285 };