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/* Callgraph construction.

   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009

   Free Software Foundation, Inc.

   Contributed by Jan Hubicka

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 3, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "tree.h"

#include "tree-flow.h"

#include "langhooks.h"

#include "pointer-set.h"

#include "cgraph.h"

#include "intl.h"

#include "gimple.h"

#include "tree-pass.h"

/* Walk tree and record all calls and references to functions/variables.

   Called via walk_tree: TP is pointer to tree to be examined.

   When DATA is non-null, record references to callgraph.

   */

static tree

record_reference (tree *tp, int *walk_subtrees, void *data)

{

  tree t = *tp;

  tree decl;

  bool do_callgraph = data != NULL;

  switch (TREE_CODE (t))

    {

    case VAR_DECL:

      if (TREE_STATIC (t) || DECL_EXTERNAL (t))

        {

          varpool_mark_needed_node (varpool_node (t));

          if (lang_hooks.callgraph.analyze_expr)

            return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees);

        }

      break;

    case FDESC_EXPR:

    case ADDR_EXPR:

      /* Record dereferences to the functions.  This makes the

         functions reachable unconditionally.  */

      decl = TREE_OPERAND (*tp, 0);

      if (TREE_CODE (decl) == FUNCTION_DECL && do_callgraph)

        cgraph_mark_address_taken_node (cgraph_node (decl));

      break;

    default:

      /* Save some cycles by not walking types and declaration as we

         won't find anything useful there anyway.  */

      if (IS_TYPE_OR_DECL_P (*tp))

        {

          *walk_subtrees = 0;

          break;

        }

      if ((unsigned int) TREE_CODE (t) >= LAST_AND_UNUSED_TREE_CODE)

        return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees);

      break;

    }

  return NULL_TREE;

}

/* Reset inlining information of all incoming call edges of NODE.  */

void

reset_inline_failed (struct cgraph_node *node)

{

  struct cgraph_edge *e;

  for (e = node->callers; e; e = e->next_caller)

    {

      e->callee->global.inlined_to = NULL;

      if (!node->analyzed)

        e->inline_failed = CIF_BODY_NOT_AVAILABLE;

      else if (node->local.redefined_extern_inline)

        e->inline_failed = CIF_REDEFINED_EXTERN_INLINE;

      else if (!node->local.inlinable)

        e->inline_failed = CIF_FUNCTION_NOT_INLINABLE;

      else if (e->call_stmt_cannot_inline_p)

        e->inline_failed = CIF_MISMATCHED_ARGUMENTS;

      else

        e->inline_failed = CIF_FUNCTION_NOT_CONSIDERED;

    }

}

/* Computes the frequency of the call statement so that it can be stored in

   cgraph_edge.  BB is the basic block of the call statement.  */

int

compute_call_stmt_bb_frequency (tree decl, basic_block bb)

{

  int entry_freq = ENTRY_BLOCK_PTR_FOR_FUNCTION

                     (DECL_STRUCT_FUNCTION (decl))->frequency;

  int freq = bb->frequency;

  if (profile_status_for_function (DECL_STRUCT_FUNCTION (decl)) == PROFILE_ABSENT)

    return CGRAPH_FREQ_BASE;

  if (!entry_freq)

    entry_freq = 1, freq++;

  freq = freq * CGRAPH_FREQ_BASE / entry_freq;

  if (freq > CGRAPH_FREQ_MAX)

    freq = CGRAPH_FREQ_MAX;

  return freq;

}

/* Create cgraph edges for function calls.

   Also look for functions and variables having addresses taken.  */

static unsigned int

build_cgraph_edges (void)

{

  basic_block bb;

  struct cgraph_node *node = cgraph_node (current_function_decl);

  struct pointer_set_t *visited_nodes = pointer_set_create ();

  gimple_stmt_iterator gsi;

  tree step;

  /* Create the callgraph edges and record the nodes referenced by the function.

     body.  */

  FOR_EACH_BB (bb)

    for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))

      {

        gimple stmt = gsi_stmt (gsi);

        tree decl;

        if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))

          {

            size_t i;

            size_t n = gimple_call_num_args (stmt);

            cgraph_create_edge (node, cgraph_node (decl), stmt,

                                bb->count, compute_call_stmt_bb_frequency (current_function_decl, bb),

                                bb->loop_depth);

            for (i = 0; i < n; i++)

              walk_tree (gimple_call_arg_ptr (stmt, i), record_reference,

                         node, visited_nodes);

            if (gimple_call_lhs (stmt))

              walk_tree (gimple_call_lhs_ptr (stmt), record_reference, node,

                         visited_nodes);

          }

        else

          {

            struct walk_stmt_info wi;

            memset (&wi, 0, sizeof (wi));

            wi.info = node;

            wi.pset = visited_nodes;

            walk_gimple_op (stmt, record_reference, &wi);

            if (gimple_code (stmt) == GIMPLE_OMP_PARALLEL

                && gimple_omp_parallel_child_fn (stmt))

              {

                tree fn = gimple_omp_parallel_child_fn (stmt);

                cgraph_mark_needed_node (cgraph_node (fn));

              }

            if (gimple_code (stmt) == GIMPLE_OMP_TASK)

              {

                tree fn = gimple_omp_task_child_fn (stmt);

                if (fn)

                  cgraph_mark_needed_node (cgraph_node (fn));

                fn = gimple_omp_task_copy_fn (stmt);

                if (fn)

                  cgraph_mark_needed_node (cgraph_node (fn));

              }

          }

      }

  /* Look for initializers of constant variables and private statics.  */

  for (step = cfun->local_decls;

       step;

       step = TREE_CHAIN (step))

    {

      tree decl = TREE_VALUE (step);

      if (TREE_CODE (decl) == VAR_DECL

          && (TREE_STATIC (decl) && !DECL_EXTERNAL (decl)))

        varpool_finalize_decl (decl);

      else if (TREE_CODE (decl) == VAR_DECL && DECL_INITIAL (decl))

        walk_tree (&DECL_INITIAL (decl), record_reference, node, visited_nodes);

    }

  pointer_set_destroy (visited_nodes);

  return 0;

}

struct gimple_opt_pass pass_build_cgraph_edges =

{

 {

  GIMPLE_PASS,

  "*build_cgraph_edges",                        /* name */

  NULL,                                 /* gate */

  build_cgraph_edges,                   /* execute */

  NULL,                                 /* sub */

  NULL,                                 /* next */

  0,                                     /* static_pass_number */

  TV_NONE,                              /* tv_id */

  PROP_cfg,                             /* properties_required */

  0,                                     /* properties_provided */

  0,                                     /* properties_destroyed */

  0,                                     /* todo_flags_start */

 }

};

/* Record references to functions and other variables present in the

   initial value of DECL, a variable.

   When ONLY_VARS is true, we mark needed only variables, not functions.  */

void

record_references_in_initializer (tree decl, bool only_vars)

{

  struct pointer_set_t *visited_nodes = pointer_set_create ();

  walk_tree (&DECL_INITIAL (decl), record_reference,

            only_vars ? NULL : decl, visited_nodes);

  pointer_set_destroy (visited_nodes);

}

/* Rebuild cgraph edges for current function node.  This needs to be run after

   passes that don't update the cgraph.  */

unsigned int

rebuild_cgraph_edges (void)

{

  basic_block bb;

  struct cgraph_node *node = cgraph_node (current_function_decl);

  gimple_stmt_iterator gsi;

  cgraph_node_remove_callees (node);

  node->count = ENTRY_BLOCK_PTR->count;

  FOR_EACH_BB (bb)

    for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))

      {

        gimple stmt = gsi_stmt (gsi);

        tree decl;

        if (is_gimple_call (stmt) && (decl = gimple_call_fndecl (stmt)))

          cgraph_create_edge (node, cgraph_node (decl), stmt,

                              bb->count,

                              compute_call_stmt_bb_frequency

                                (current_function_decl, bb),

                              bb->loop_depth);

      }

  gcc_assert (!node->global.inlined_to);

  return 0;

}

struct gimple_opt_pass pass_rebuild_cgraph_edges =

{

 {

  GIMPLE_PASS,

  "*rebuild_cgraph_edges",              /* name */

  NULL,                                 /* gate */

  rebuild_cgraph_edges,                 /* execute */

  NULL,                                 /* sub */

  NULL,                                 /* next */

  0,                                     /* static_pass_number */

  TV_NONE,                              /* tv_id */

  PROP_cfg,                             /* properties_required */

  0,                                     /* properties_provided */

  0,                                     /* properties_destroyed */

  0,                                     /* todo_flags_start */

  0,                                     /* todo_flags_finish */

 }

};

static unsigned int

remove_cgraph_callee_edges (void)

{

  cgraph_node_remove_callees (cgraph_node (current_function_decl));

  return 0;

}

struct gimple_opt_pass pass_remove_cgraph_callee_edges =

{

 {

  GIMPLE_PASS,

  "*remove_cgraph_callee_edges",                /* name */

  NULL,                                 /* gate */

  remove_cgraph_callee_edges,           /* execute */

  NULL,                                 /* sub */

  NULL,                                 /* next */

  0,                                     /* static_pass_number */

  TV_NONE,                              /* tv_id */

  0,                                     /* properties_required */

  0,                                     /* properties_provided */

  0,                                     /* properties_destroyed */

  0,                                     /* todo_flags_start */

  0,                                     /* todo_flags_finish */

 }

};