gcc/cgraphbuild.c

   1 /* Callgraph construction.
   2    Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008
   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_needed_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 (basic_block bb)
  85 {
  86   int entry_freq = ENTRY_BLOCK_PTR->frequency;
  87   int freq = bb->frequency;
  88
  89   if (!entry_freq)
  90     entry_freq = 1, freq++;
  91
  92   freq = freq * CGRAPH_FREQ_BASE / entry_freq;
  93   if (freq > CGRAPH_FREQ_MAX)
  94     freq = CGRAPH_FREQ_MAX;
  95
  96   return freq;
  97 }
  98
  99 /* Create cgraph edges for function calls.
 100    Also look for functions and variables having addresses taken.  */
 101
 102 static unsigned int
 103 build_cgraph_edges (void)
 104 {
 105   basic_block bb;
 106   struct cgraph_node *node = cgraph_node (current_function_decl);
 107   struct pointer_set_t *visited_nodes = pointer_set_create ();
 108   gimple_stmt_iterator gsi;
 109   tree step;
 110
 111   /* Create the callgraph edges and record the nodes referenced by the function.
 112      body.  */
 113   FOR_EACH_BB (bb)
 114     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 115       {
 116         gimple stmt = gsi_stmt (gsi);
 117         tree decl;
 118
 119         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 120           {
 121             size_t i;
 122             size_t n = gimple_call_num_args (stmt);
 123             cgraph_create_edge (node, cgraph_node (decl), stmt,
 124                                 bb->count, compute_call_stmt_bb_frequency (bb),
 125                                 bb->loop_depth);
 126             for (i = 0; i < n; i++)
 127               walk_tree (gimple_call_arg_ptr (stmt, i), record_reference,
 128                          node, visited_nodes);
 129             if (gimple_call_lhs (stmt))
 130               walk_tree (gimple_call_lhs_ptr (stmt), record_reference, node,
 131                          visited_nodes);
 132           }
 133         else
 134           {
 135             struct walk_stmt_info wi;
 136             memset (&wi, 0, sizeof (wi));
 137             wi.info = node;
 138             wi.pset = visited_nodes;
 139             walk_gimple_op (stmt, record_reference, &wi);
 140             if (gimple_code (stmt) == GIMPLE_OMP_PARALLEL
 141                 && gimple_omp_parallel_child_fn (stmt))
 142               {
 143                 tree fn = gimple_omp_parallel_child_fn (stmt);
 144                 cgraph_mark_needed_node (cgraph_node (fn));
 145               }
 146             if (gimple_code (stmt) == GIMPLE_OMP_TASK)
 147               {
 148                 tree fn = gimple_omp_task_child_fn (stmt);
 149                 if (fn)
 150                   cgraph_mark_needed_node (cgraph_node (fn));
 151                 fn = gimple_omp_task_copy_fn (stmt);
 152                 if (fn)
 153                   cgraph_mark_needed_node (cgraph_node (fn));
 154               }
 155           }
 156       }
 157
 158   /* Look for initializers of constant variables and private statics.  */
 159   for (step = cfun->local_decls;
 160        step;
 161        step = TREE_CHAIN (step))
 162     {
 163       tree decl = TREE_VALUE (step);
 164       if (TREE_CODE (decl) == VAR_DECL
 165           && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl)))
 166         varpool_finalize_decl (decl);
 167       else if (TREE_CODE (decl) == VAR_DECL && DECL_INITIAL (decl))
 168         walk_tree (&DECL_INITIAL (decl), record_reference, node, visited_nodes);
 169     }
 170
 171   pointer_set_destroy (visited_nodes);
 172   return 0;
 173 }
 174
 175 struct gimple_opt_pass pass_build_cgraph_edges =
 176 {
 177  {
 178   GIMPLE_PASS,
 179   NULL,                                 /* name */
 180   NULL,                                 /* gate */
 181   build_cgraph_edges,                   /* execute */
 182   NULL,                                 /* sub */
 183   NULL,                                 /* next */
 184   0,                                    /* static_pass_number */
 185   0,                                    /* tv_id */
 186   PROP_cfg,                             /* properties_required */
 187   0,                                    /* properties_provided */
 188   0,                                    /* properties_destroyed */
 189   0,                                    /* todo_flags_start */
 190   0                                     /* todo_flags_finish */
 191  }
 192 };
 193
 194 /* Record references to functions and other variables present in the
 195    initial value of DECL, a variable.  */
 196
 197 void
 198 record_references_in_initializer (tree decl)
 199 {
 200   struct pointer_set_t *visited_nodes = pointer_set_create ();
 201   walk_tree (&DECL_INITIAL (decl), record_reference, NULL, visited_nodes);
 202   pointer_set_destroy (visited_nodes);
 203 }
 204
 205 /* Rebuild cgraph edges for current function node.  This needs to be run after
 206    passes that don't update the cgraph.  */
 207
 208 unsigned int
 209 rebuild_cgraph_edges (void)
 210 {
 211   basic_block bb;
 212   struct cgraph_node *node = cgraph_node (current_function_decl);
 213   gimple_stmt_iterator gsi;
 214
 215   cgraph_node_remove_callees (node);
 216
 217   node->count = ENTRY_BLOCK_PTR->count;
 218
 219   FOR_EACH_BB (bb)
 220     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 221       {
 222         gimple stmt = gsi_stmt (gsi);
 223         tree decl;
 224
 225         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 226           cgraph_create_edge (node, cgraph_node (decl), stmt,
 227                               bb->count, compute_call_stmt_bb_frequency (bb),
 228                               bb->loop_depth);
 229
 230       }
 231   gcc_assert (!node->global.inlined_to);
 232
 233   return 0;
 234 }
 235
 236 struct gimple_opt_pass pass_rebuild_cgraph_edges =
 237 {
 238  {
 239   GIMPLE_PASS,
 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  }
 253 };