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 3, 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 COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "tree.h"
  26 #include "tree-flow.h"
  27 #include "langhooks.h"
  28 #include "pointer-set.h"
  29 #include "cgraph.h"
  30 #include "intl.h"
  31 #include "tree-gimple.h"
  32 #include "tree-pass.h"
  33
  34 /* Walk tree and record all calls and references to functions/variables.
  35    Called via walk_tree: TP is pointer to tree to be examined.  */
  36
  37 static tree
  38 record_reference (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
  39 {
  40   tree t = *tp;
  41
  42   switch (TREE_CODE (t))
  43     {
  44     case VAR_DECL:
  45       if (TREE_STATIC (t) || DECL_EXTERNAL (t))
  46         {
  47           varpool_mark_needed_node (varpool_node (t));
  48           if (lang_hooks.callgraph.analyze_expr)
  49             return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees);
  50         }
  51       break;
  52
  53     case FDESC_EXPR:
  54     case ADDR_EXPR:
  55       if (flag_unit_at_a_time)
  56         {
  57           /* Record dereferences to the functions.  This makes the
  58              functions reachable unconditionally.  */
  59           tree decl = TREE_OPERAND (*tp, 0);
  60           if (TREE_CODE (decl) == FUNCTION_DECL)
  61             cgraph_mark_needed_node (cgraph_node (decl));
  62         }
  63       break;
  64
  65     case OMP_PARALLEL:
  66       if (flag_unit_at_a_time)
  67         {
  68           if (OMP_PARALLEL_FN (*tp))
  69             cgraph_mark_needed_node (cgraph_node (OMP_PARALLEL_FN (*tp)));
  70         }
  71       break;
  72
  73     case OMP_TASK:
  74       if (flag_unit_at_a_time)
  75         {
  76           if (OMP_TASK_FN (*tp))
  77             cgraph_mark_needed_node (cgraph_node (OMP_TASK_FN (*tp)));
  78           if (OMP_TASK_COPYFN (*tp))
  79             cgraph_mark_needed_node (cgraph_node (OMP_TASK_COPYFN (*tp)));
  80         }
  81       break;
  82
  83     default:
  84       /* Save some cycles by not walking types and declaration as we
  85          won't find anything useful there anyway.  */
  86       if (IS_TYPE_OR_DECL_P (*tp))
  87         {
  88           *walk_subtrees = 0;
  89           break;
  90         }
  91
  92       if ((unsigned int) TREE_CODE (t) >= LAST_AND_UNUSED_TREE_CODE)
  93         return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees);
  94       break;
  95     }
  96
  97   return NULL_TREE;
  98 }
  99
 100 /* Give initial reasons why inlining would fail on all calls from
 101    NODE.  Those get either nullified or usually overwritten by more precise
 102    reason later.  */
 103
 104 static void
 105 initialize_inline_failed (struct cgraph_node *node)
 106 {
 107   struct cgraph_edge *e;
 108
 109   for (e = node->callers; e; e = e->next_caller)
 110     {
 111       gcc_assert (!e->callee->global.inlined_to);
 112       gcc_assert (e->inline_failed);
 113       if (node->local.redefined_extern_inline)
 114         e->inline_failed = N_("redefined extern inline functions are not "
 115                            "considered for inlining");
 116       else if (!node->local.inlinable)
 117         e->inline_failed = N_("function not inlinable");
 118       else if (CALL_STMT_CANNOT_INLINE_P (e->call_stmt))
 119         e->inline_failed = N_("mismatched arguments");
 120       else
 121         e->inline_failed = N_("function not considered for inlining");
 122     }
 123 }
 124
 125 /* Computes the frequency of the call statement so that it can be stored in
 126    cgraph_edge.  BB is the basic block of the call statement.  */
 127 int
 128 compute_call_stmt_bb_frequency (basic_block bb)
 129 {
 130   int entry_freq = ENTRY_BLOCK_PTR->frequency;
 131   int freq;
 132
 133   if (!entry_freq)
 134     entry_freq = 1;
 135
 136   freq = (!bb->frequency && !entry_freq ? CGRAPH_FREQ_BASE
 137               : bb->frequency * CGRAPH_FREQ_BASE / entry_freq);
 138   if (freq > CGRAPH_FREQ_MAX)
 139     freq = CGRAPH_FREQ_MAX;
 140
 141   return freq;
 142 }
 143
 144 /* Create cgraph edges for function calls.
 145    Also look for functions and variables having addresses taken.  */
 146
 147 static unsigned int
 148 build_cgraph_edges (void)
 149 {
 150   basic_block bb;
 151   struct cgraph_node *node = cgraph_node (current_function_decl);
 152   struct pointer_set_t *visited_nodes = pointer_set_create ();
 153   block_stmt_iterator bsi;
 154   tree step;
 155
 156   /* Create the callgraph edges and record the nodes referenced by the function.
 157      body.  */
 158   FOR_EACH_BB (bb)
 159     for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
 160       {
 161         tree stmt = bsi_stmt (bsi);
 162         tree call = get_call_expr_in (stmt);
 163         tree decl;
 164
 165         if (call && (decl = get_callee_fndecl (call)))
 166           {
 167             int i;
 168             int n = call_expr_nargs (call);
 169             cgraph_create_edge (node, cgraph_node (decl), stmt,
 170                                 bb->count, compute_call_stmt_bb_frequency (bb),
 171                                 bb->loop_depth);
 172             for (i = 0; i < n; i++)
 173               walk_tree (&CALL_EXPR_ARG (call, i),
 174                          record_reference, node, visited_nodes);
 175             if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
 176               walk_tree (&GIMPLE_STMT_OPERAND (stmt, 0),
 177                          record_reference, node, visited_nodes);
 178           }
 179         else
 180           walk_tree (bsi_stmt_ptr (bsi), record_reference, node, visited_nodes);
 181       }
 182
 183   /* Look for initializers of constant variables and private statics.  */
 184   for (step = cfun->local_decls;
 185        step;
 186        step = TREE_CHAIN (step))
 187     {
 188       tree decl = TREE_VALUE (step);
 189       if (TREE_CODE (decl) == VAR_DECL
 190           && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 191           && flag_unit_at_a_time)
 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   block_stmt_iterator bsi;
 241
 242   cgraph_node_remove_callees (node);
 243
 244   node->count = ENTRY_BLOCK_PTR->count;
 245
 246   FOR_EACH_BB (bb)
 247     for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
 248       {
 249         tree stmt = bsi_stmt (bsi);
 250         tree call = get_call_expr_in (stmt);
 251         tree decl;
 252
 253         if (call && (decl = get_callee_fndecl (call)))
 254           cgraph_create_edge (node, cgraph_node (decl), stmt,
 255                               bb->count, compute_call_stmt_bb_frequency (bb),
 256                               bb->loop_depth);
 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 };