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/* Basic IPA optimizations and utilities.

   Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.

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 2, 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 COPYING.  If not, write to the Free

Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "cgraph.h"

/* Fill array order with all nodes with output flag set in the reverse

   topological order.  */

int

cgraph_postorder (struct cgraph_node **order)

{

  struct cgraph_node *node, *node2;

  int stack_size = 0;

  int order_pos = 0;

  struct cgraph_edge *edge, last;

  struct cgraph_node **stack =

    xcalloc (cgraph_n_nodes, sizeof (struct cgraph_node *));

  /* We have to deal with cycles nicely, so use a depth first traversal

     output algorithm.  Ignore the fact that some functions won't need

     to be output and put them into order as well, so we get dependencies

     right through intline functions.  */

  for (node = cgraph_nodes; node; node = node->next)

    node->aux = NULL;

  for (node = cgraph_nodes; node; node = node->next)

    if (!node->aux)

      {

        node2 = node;

        if (!node->callers)

          node->aux = &last;

        else

          node->aux = node->callers;

        while (node2)

          {

            while (node2->aux != &last)

              {

                edge = node2->aux;

                if (edge->next_caller)

                  node2->aux = edge->next_caller;

                else

                  node2->aux = &last;

                if (!edge->caller->aux)

                  {

                    if (!edge->caller->callers)

                      edge->caller->aux = &last;

                    else

                      edge->caller->aux = edge->caller->callers;

                    stack[stack_size++] = node2;

                    node2 = edge->caller;

                    break;

                  }

              }

            if (node2->aux == &last)

              {

                order[order_pos++] = node2;

                if (stack_size)

                  node2 = stack[--stack_size];

                else

                  node2 = NULL;

              }

          }

      }

  free (stack);

  for (node = cgraph_nodes; node; node = node->next)

    node->aux = NULL;

  return order_pos;

}

/* Perform reachability analysis and reclaim all unreachable nodes.

   If BEFORE_INLINING_P is true this function is called before inlining

   decisions has been made.  If BEFORE_INLINING_P is false this function also

   removes unneeded bodies of extern inline functions.  */

bool

cgraph_remove_unreachable_nodes (bool before_inlining_p, FILE *dump_file)

{

  struct cgraph_node *first = (void *) 1;

  struct cgraph_node *node;

  bool changed = false;

  int insns = 0;

#ifdef ENABLE_CHECKING

  verify_cgraph ();

#endif

  if (dump_file)

    fprintf (dump_file, "\nReclaiming functions:");

#ifdef ENABLE_CHECKING

  for (node = cgraph_nodes; node; node = node->next)

    gcc_assert (!node->aux);

#endif

  for (node = cgraph_nodes; node; node = node->next)

    if (node->needed && !node->global.inlined_to

        && ((!DECL_EXTERNAL (node->decl))

            || !node->analyzed

            || before_inlining_p))

      {

        node->aux = first;

        first = node;

      }

    else

      gcc_assert (!node->aux);

  /* Perform reachability analysis.  As a special case do not consider

     extern inline functions not inlined as live because we won't output

     them at all.  */

  while (first != (void *) 1)

    {

      struct cgraph_edge *e;

      node = first;

      first = first->aux;

      for (e = node->callees; e; e = e->next_callee)

        if (!e->callee->aux

            && node->analyzed

            && (!e->inline_failed || !e->callee->analyzed

                || (!DECL_EXTERNAL (e->callee->decl))

                || before_inlining_p))

          {

            e->callee->aux = first;

            first = e->callee;

          }

    }

  /* Remove unreachable nodes.  Extern inline functions need special care;

     Unreachable extern inline functions shall be removed.

     Reachable extern inline functions we never inlined shall get their bodies

     eliminated.

     Reachable extern inline functions we sometimes inlined will be turned into

     unanalyzed nodes so they look like for true extern functions to the rest

     of code.  Body of such functions is released via remove_node once the

     inline clones are eliminated.  */

  for (node = cgraph_nodes; node; node = node->next)

    {

      if (!node->aux)

        {

          int local_insns;

          tree decl = node->decl;

          node->global.inlined_to = NULL;

          if (DECL_STRUCT_FUNCTION (decl))

            local_insns = node->local.self_insns;

          else

            local_insns = 0;

          if (dump_file)

            fprintf (dump_file, " %s", cgraph_node_name (node));

          if (!node->analyzed || !DECL_EXTERNAL (node->decl)

              || before_inlining_p)

            cgraph_remove_node (node);

          else

            {

              struct cgraph_edge *e;

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

                if (e->caller->aux)

                  break;

              if (e || node->needed)

                {

                  struct cgraph_node *clone;

                  for (clone = node->next_clone; clone;

                       clone = clone->next_clone)

                    if (clone->aux)

                      break;

                  if (!clone)

                    {

                      DECL_SAVED_TREE (node->decl) = NULL;

                      DECL_STRUCT_FUNCTION (node->decl) = NULL;

                      DECL_INITIAL (node->decl) = error_mark_node;

                      node->analyzed = false;

                    }

                  cgraph_node_remove_callees (node);

                  node->analyzed = false;

                }

              else

                cgraph_remove_node (node);

            }

          if (!DECL_SAVED_TREE (decl))

            insns += local_insns;

          changed = true;

        }

    }

  for (node = cgraph_nodes; node; node = node->next)

    node->aux = NULL;

  if (dump_file)

    fprintf (dump_file, "\nReclaimed %i insns", insns);

  return changed;

}