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 /* Give initial reasons why inlining would fail on all calls from
  82    NODE.  Those get either nullified or usually overwritten by more precise
  83    reason later.  */
  84
  85 static void
  86 initialize_inline_failed (struct cgraph_node *node)
  87 {
  88   struct cgraph_edge *e;
  89
  90   for (e = node->callers; e; e = e->next_caller)
  91     {
  92       gcc_assert (!e->callee->global.inlined_to);
  93       gcc_assert (e->inline_failed);
  94       if (node->local.redefined_extern_inline)
  95         e->inline_failed = N_("redefined extern inline functions are not "
  96                            "considered for inlining");
  97       else if (!node->local.inlinable)
  98         e->inline_failed = N_("function not inlinable");
  99       else if (gimple_call_cannot_inline_p (e->call_stmt))
 100         e->inline_failed = N_("mismatched arguments");
 101       else
 102         e->inline_failed = N_("function not considered for inlining");
 103     }
 104 }
 105
 106 /* Computes the frequency of the call statement so that it can be stored in
 107    cgraph_edge.  BB is the basic block of the call statement.  */
 108 int
 109 compute_call_stmt_bb_frequency (basic_block bb)
 110 {
 111   int entry_freq = ENTRY_BLOCK_PTR->frequency;
 112   int freq;
 113
 114   if (!entry_freq)
 115     entry_freq = 1;
 116
 117   freq = (!bb->frequency && !entry_freq ? CGRAPH_FREQ_BASE
 118               : bb->frequency * CGRAPH_FREQ_BASE / entry_freq);
 119   if (freq > CGRAPH_FREQ_MAX)
 120     freq = CGRAPH_FREQ_MAX;
 121
 122   return freq;
 123 }
 124
 125 /* Create cgraph edges for function calls.
 126    Also look for functions and variables having addresses taken.  */
 127
 128 static unsigned int
 129 build_cgraph_edges (void)
 130 {
 131   basic_block bb;
 132   struct cgraph_node *node = cgraph_node (current_function_decl);
 133   struct pointer_set_t *visited_nodes = pointer_set_create ();
 134   gimple_stmt_iterator gsi;
 135   tree step;
 136
 137   /* Create the callgraph edges and record the nodes referenced by the function.
 138      body.  */
 139   FOR_EACH_BB (bb)
 140     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 141       {
 142         gimple stmt = gsi_stmt (gsi);
 143         tree decl;
 144
 145         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 146           {
 147             size_t i;
 148             size_t n = gimple_call_num_args (stmt);
 149             cgraph_create_edge (node, cgraph_node (decl), stmt,
 150                                 bb->count, compute_call_stmt_bb_frequency (bb),
 151                                 bb->loop_depth);
 152             for (i = 0; i < n; i++)
 153               walk_tree (gimple_call_arg_ptr (stmt, i), record_reference,
 154                          node, visited_nodes);
 155             if (gimple_call_lhs (stmt))
 156               walk_tree (gimple_call_lhs_ptr (stmt), record_reference, node,
 157                          visited_nodes);
 158           }
 159         else
 160           {
 161             struct walk_stmt_info wi;
 162             memset (&wi, 0, sizeof (wi));
 163             wi.info = node;
 164             wi.pset = visited_nodes;
 165             walk_gimple_op (stmt, record_reference, &wi);
 166             if (gimple_code (stmt) == GIMPLE_OMP_PARALLEL
 167                 && gimple_omp_parallel_child_fn (stmt))
 168               {
 169                 tree fn = gimple_omp_parallel_child_fn (stmt);
 170                 cgraph_mark_needed_node (cgraph_node (fn));
 171               }
 172             if (gimple_code (stmt) == GIMPLE_OMP_TASK)
 173               {
 174                 tree fn = gimple_omp_task_child_fn (stmt);
 175                 if (fn)
 176                   cgraph_mark_needed_node (cgraph_node (fn));
 177                 fn = gimple_omp_task_copy_fn (stmt);
 178                 if (fn)
 179                   cgraph_mark_needed_node (cgraph_node (fn));
 180               }
 181           }
 182       }
 183
 184   /* Look for initializers of constant variables and private statics.  */
 185   for (step = cfun->local_decls;
 186        step;
 187        step = TREE_CHAIN (step))
 188     {
 189       tree decl = TREE_VALUE (step);
 190       if (TREE_CODE (decl) == VAR_DECL
 191           && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl)))
 192         varpool_finalize_decl (decl);
 193       else if (TREE_CODE (decl) == VAR_DECL && DECL_INITIAL (decl))
 194         walk_tree (&DECL_INITIAL (decl), record_reference, node, visited_nodes);
 195     }
 196
 197   pointer_set_destroy (visited_nodes);
 198   initialize_inline_failed (node);
 199   return 0;
 200 }
 201
 202 struct gimple_opt_pass pass_build_cgraph_edges =
 203 {
 204  {
 205   GIMPLE_PASS,
 206   NULL,                                 /* name */
 207   NULL,                                 /* gate */
 208   build_cgraph_edges,                   /* execute */
 209   NULL,                                 /* sub */
 210   NULL,                                 /* next */
 211   0,                                    /* static_pass_number */
 212   0,                                    /* tv_id */
 213   PROP_cfg,                             /* properties_required */
 214   0,                                    /* properties_provided */
 215   0,                                    /* properties_destroyed */
 216   0,                                    /* todo_flags_start */
 217   0                                     /* todo_flags_finish */
 218  }
 219 };
 220
 221 /* Record references to functions and other variables present in the
 222    initial value of DECL, a variable.  */
 223
 224 void
 225 record_references_in_initializer (tree decl)
 226 {
 227   struct pointer_set_t *visited_nodes = pointer_set_create ();
 228   walk_tree (&DECL_INITIAL (decl), record_reference, NULL, visited_nodes);
 229   pointer_set_destroy (visited_nodes);
 230 }
 231
 232 /* Rebuild cgraph edges for current function node.  This needs to be run after
 233    passes that don't update the cgraph.  */
 234
 235 unsigned int
 236 rebuild_cgraph_edges (void)
 237 {
 238   basic_block bb;
 239   struct cgraph_node *node = cgraph_node (current_function_decl);
 240   gimple_stmt_iterator gsi;
 241
 242   cgraph_node_remove_callees (node);
 243
 244   node->count = ENTRY_BLOCK_PTR->count;
 245
 246   FOR_EACH_BB (bb)
 247     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 248       {
 249         gimple stmt = gsi_stmt (gsi);
 250         tree decl;
 251
 252         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 253           cgraph_create_edge (node, cgraph_node (decl), stmt,
 254                               bb->count, compute_call_stmt_bb_frequency (bb),
 255                               bb->loop_depth);
 256
 257       }
 258   initialize_inline_failed (node);
 259   gcc_assert (!node->global.inlined_to);
 260   return 0;
 261 }
 262
 263 struct gimple_opt_pass pass_rebuild_cgraph_edges =
 264 {
 265  {
 266   GIMPLE_PASS,
 267   NULL,                                 /* name */
 268   NULL,                                 /* gate */
 269   rebuild_cgraph_edges,                 /* execute */
 270   NULL,                                 /* sub */
 271   NULL,                                 /* next */
 272   0,                                    /* static_pass_number */
 273   0,                                    /* tv_id */
 274   PROP_cfg,                             /* properties_required */
 275   0,                                    /* properties_provided */
 276   0,                                    /* properties_destroyed */
 277   0,                                    /* todo_flags_start */
 278   0,                                    /* todo_flags_finish */
 279  }
 280 };