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 = bb->frequency;
 113
 114   if (!entry_freq)
 115     entry_freq = 1, freq++;
 116
 117   freq = freq * CGRAPH_FREQ_BASE / entry_freq;
 118   if (freq > CGRAPH_FREQ_MAX)
 119     freq = CGRAPH_FREQ_MAX;
 120
 121   return freq;
 122 }
 123
 124 /* Create cgraph edges for function calls.
 125    Also look for functions and variables having addresses taken.  */
 126
 127 static unsigned int
 128 build_cgraph_edges (void)
 129 {
 130   basic_block bb;
 131   struct cgraph_node *node = cgraph_node (current_function_decl);
 132   struct pointer_set_t *visited_nodes = pointer_set_create ();
 133   gimple_stmt_iterator gsi;
 134   tree step;
 135
 136   /* Create the callgraph edges and record the nodes referenced by the function.
 137      body.  */
 138   FOR_EACH_BB (bb)
 139     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 140       {
 141         gimple stmt = gsi_stmt (gsi);
 142         tree decl;
 143
 144         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 145           {
 146             size_t i;
 147             size_t n = gimple_call_num_args (stmt);
 148             cgraph_create_edge (node, cgraph_node (decl), stmt,
 149                                 bb->count, compute_call_stmt_bb_frequency (bb),
 150                                 bb->loop_depth);
 151             for (i = 0; i < n; i++)
 152               walk_tree (gimple_call_arg_ptr (stmt, i), record_reference,
 153                          node, visited_nodes);
 154             if (gimple_call_lhs (stmt))
 155               walk_tree (gimple_call_lhs_ptr (stmt), record_reference, node,
 156                          visited_nodes);
 157           }
 158         else
 159           {
 160             struct walk_stmt_info wi;
 161             memset (&wi, 0, sizeof (wi));
 162             wi.info = node;
 163             wi.pset = visited_nodes;
 164             walk_gimple_op (stmt, record_reference, &wi);
 165             if (gimple_code (stmt) == GIMPLE_OMP_PARALLEL
 166                 && gimple_omp_parallel_child_fn (stmt))
 167               {
 168                 tree fn = gimple_omp_parallel_child_fn (stmt);
 169                 cgraph_mark_needed_node (cgraph_node (fn));
 170               }
 171             if (gimple_code (stmt) == GIMPLE_OMP_TASK)
 172               {
 173                 tree fn = gimple_omp_task_child_fn (stmt);
 174                 if (fn)
 175                   cgraph_mark_needed_node (cgraph_node (fn));
 176                 fn = gimple_omp_task_copy_fn (stmt);
 177                 if (fn)
 178                   cgraph_mark_needed_node (cgraph_node (fn));
 179               }
 180           }
 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         varpool_finalize_decl (decl);
 192       else if (TREE_CODE (decl) == VAR_DECL && DECL_INITIAL (decl))
 193         walk_tree (&DECL_INITIAL (decl), record_reference, node, visited_nodes);
 194     }
 195
 196   pointer_set_destroy (visited_nodes);
 197   initialize_inline_failed (node);
 198   return 0;
 199 }
 200
 201 struct gimple_opt_pass pass_build_cgraph_edges =
 202 {
 203  {
 204   GIMPLE_PASS,
 205   NULL,                                 /* name */
 206   NULL,                                 /* gate */
 207   build_cgraph_edges,                   /* execute */
 208   NULL,                                 /* sub */
 209   NULL,                                 /* next */
 210   0,                                    /* static_pass_number */
 211   0,                                    /* tv_id */
 212   PROP_cfg,                             /* properties_required */
 213   0,                                    /* properties_provided */
 214   0,                                    /* properties_destroyed */
 215   0,                                    /* todo_flags_start */
 216   0                                     /* todo_flags_finish */
 217  }
 218 };
 219
 220 /* Record references to functions and other variables present in the
 221    initial value of DECL, a variable.  */
 222
 223 void
 224 record_references_in_initializer (tree decl)
 225 {
 226   struct pointer_set_t *visited_nodes = pointer_set_create ();
 227   walk_tree (&DECL_INITIAL (decl), record_reference, NULL, visited_nodes);
 228   pointer_set_destroy (visited_nodes);
 229 }
 230
 231 /* Rebuild cgraph edges for current function node.  This needs to be run after
 232    passes that don't update the cgraph.  */
 233
 234 unsigned int
 235 rebuild_cgraph_edges (void)
 236 {
 237   basic_block bb;
 238   struct cgraph_node *node = cgraph_node (current_function_decl);
 239   gimple_stmt_iterator gsi;
 240
 241   cgraph_node_remove_callees (node);
 242
 243   node->count = ENTRY_BLOCK_PTR->count;
 244
 245   FOR_EACH_BB (bb)
 246     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 247       {
 248         gimple stmt = gsi_stmt (gsi);
 249         tree decl;
 250
 251         if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))
 252           cgraph_create_edge (node, cgraph_node (decl), stmt,
 253                               bb->count, compute_call_stmt_bb_frequency (bb),
 254                               bb->loop_depth);
 255
 256       }
 257   initialize_inline_failed (node);
 258   gcc_assert (!node->global.inlined_to);
 259   return 0;
 260 }
 261
 262 struct gimple_opt_pass pass_rebuild_cgraph_edges =
 263 {
 264  {
 265   GIMPLE_PASS,
 266   NULL,                                 /* name */
 267   NULL,                                 /* gate */
 268   rebuild_cgraph_edges,                 /* execute */
 269   NULL,                                 /* sub */
 270   NULL,                                 /* next */
 271   0,                                    /* static_pass_number */
 272   0,                                    /* tv_id */
 273   PROP_cfg,                             /* properties_required */
 274   0,                                    /* properties_provided */
 275   0,                                    /* properties_destroyed */
 276   0,                                    /* todo_flags_start */
 277   0,                                    /* todo_flags_finish */
 278  }
 279 };