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 /* 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   block_stmt_iterator bsi;
 135   tree step;
 136   int entry_freq = ENTRY_BLOCK_PTR->frequency;
 137
 138   if (!entry_freq)
 139     entry_freq = 1;
 140
 141   /* Create the callgraph edges and record the nodes referenced by the function.
 142      body.  */
 143   FOR_EACH_BB (bb)
 144     for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
 145       {
 146         tree stmt = bsi_stmt (bsi);
 147         tree call = get_call_expr_in (stmt);
 148         tree decl;
 149
 150         if (call && (decl = get_callee_fndecl (call)))
 151           {
 152             int i;
 153             int n = call_expr_nargs (call);
 154             int freq = (!bb->frequency && !entry_freq ? CGRAPH_FREQ_BASE
 155                         : bb->frequency * CGRAPH_FREQ_BASE / entry_freq);
 156             if (freq > CGRAPH_FREQ_MAX)
 157               freq = CGRAPH_FREQ_MAX;
 158             cgraph_create_edge (node, cgraph_node (decl), stmt,
 159                                 bb->count, freq,
 160                                 bb->loop_depth);
 161             for (i = 0; i < n; i++)
 162               walk_tree (&CALL_EXPR_ARG (call, i),
 163                          record_reference, node, visited_nodes);
 164             if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
 165               walk_tree (&GIMPLE_STMT_OPERAND (stmt, 0),
 166                          record_reference, node, visited_nodes);
 167           }
 168         else
 169           walk_tree (bsi_stmt_ptr (bsi), record_reference, node, visited_nodes);
 170       }
 171
 172   /* Look for initializers of constant variables and private statics.  */
 173   for (step = cfun->local_decls;
 174        step;
 175        step = TREE_CHAIN (step))
 176     {
 177       tree decl = TREE_VALUE (step);
 178       if (TREE_CODE (decl) == VAR_DECL
 179           && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 180           && flag_unit_at_a_time)
 181         varpool_finalize_decl (decl);
 182       else if (TREE_CODE (decl) == VAR_DECL && DECL_INITIAL (decl))
 183         walk_tree (&DECL_INITIAL (decl), record_reference, node, visited_nodes);
 184     }
 185
 186   pointer_set_destroy (visited_nodes);
 187   initialize_inline_failed (node);
 188   return 0;
 189 }
 190
 191 struct gimple_opt_pass pass_build_cgraph_edges =
 192 {
 193  {
 194   GIMPLE_PASS,
 195   NULL,                                 /* name */
 196   NULL,                                 /* gate */
 197   build_cgraph_edges,                   /* execute */
 198   NULL,                                 /* sub */
 199   NULL,                                 /* next */
 200   0,                                    /* static_pass_number */
 201   0,                                    /* tv_id */
 202   PROP_cfg,                             /* properties_required */
 203   0,                                    /* properties_provided */
 204   0,                                    /* properties_destroyed */
 205   0,                                    /* todo_flags_start */
 206   0                                     /* todo_flags_finish */
 207  }
 208 };
 209
 210 /* Record references to functions and other variables present in the
 211    initial value of DECL, a variable.  */
 212
 213 void
 214 record_references_in_initializer (tree decl)
 215 {
 216   struct pointer_set_t *visited_nodes = pointer_set_create ();
 217   walk_tree (&DECL_INITIAL (decl), record_reference, NULL, visited_nodes);
 218   pointer_set_destroy (visited_nodes);
 219 }
 220
 221 /* Rebuild cgraph edges for current function node.  This needs to be run after
 222    passes that don't update the cgraph.  */
 223
 224 unsigned int
 225 rebuild_cgraph_edges (void)
 226 {
 227   basic_block bb;
 228   struct cgraph_node *node = cgraph_node (current_function_decl);
 229   block_stmt_iterator bsi;
 230   int entry_freq = ENTRY_BLOCK_PTR->frequency;
 231
 232   if (!entry_freq)
 233     entry_freq = 1;
 234
 235   cgraph_node_remove_callees (node);
 236
 237   node->count = ENTRY_BLOCK_PTR->count;
 238
 239   FOR_EACH_BB (bb)
 240     for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
 241       {
 242         tree stmt = bsi_stmt (bsi);
 243         tree call = get_call_expr_in (stmt);
 244         tree decl;
 245
 246         if (call && (decl = get_callee_fndecl (call)))
 247           {
 248             int freq = (!bb->frequency && !entry_freq ? CGRAPH_FREQ_BASE
 249                         : bb->frequency * CGRAPH_FREQ_BASE / entry_freq);
 250             if (freq > CGRAPH_FREQ_MAX)
 251               freq = CGRAPH_FREQ_MAX;
 252             cgraph_create_edge (node, cgraph_node (decl), stmt,
 253                                 bb->count, freq, bb->loop_depth);
 254            }
 255       }
 256   initialize_inline_failed (node);
 257   gcc_assert (!node->global.inlined_to);
 258   return 0;
 259 }
 260
 261 struct gimple_opt_pass pass_rebuild_cgraph_edges =
 262 {
 263  {
 264   GIMPLE_PASS,
 265   NULL,                                 /* name */
 266   NULL,                                 /* gate */
 267   rebuild_cgraph_edges,                 /* execute */
 268   NULL,                                 /* sub */
 269   NULL,                                 /* next */
 270   0,                                    /* static_pass_number */
 271   0,                                    /* tv_id */
 272   PROP_cfg,                             /* properties_required */
 273   0,                                    /* properties_provided */
 274   0,                                    /* properties_destroyed */
 275   0,                                    /* todo_flags_start */
 276   0,                                    /* todo_flags_finish */
 277  }
 278 };