text: /* 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 =
      XCNEWVEC (struct cgraph_node *, cgraph_n_nodes);
  
    /* 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 *file)
  {
    struct cgraph_node *first = (void *) 1;
    struct cgraph_node *node, *next;
    bool changed = false;
    int insns = 0;
  
  #ifdef ENABLE_CHECKING
    verify_cgraph ();
  #endif
    if (file)
      fprintf (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 = next)
      {
        next = 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 (file)
  	    fprintf (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 (file)
      fprintf (file, "\nReclaimed %i insns", insns);
    return changed;
  }
  