path: root/gcc/ipa-utils.c

/* Utilities for ipa analysis.
   Copyright (C) 2005, 2007, 2008 Free Software Foundation, Inc.
   Contributed by Kenneth Zadeck <zadeck@naturalbridge.com>

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 "tree-inline.h"
#include "tree-pass.h"
#include "langhooks.h"
#include "pointer-set.h"
#include "splay-tree.h"
#include "ggc.h"
#include "ipa-utils.h"
#include "ipa-reference.h"
#include "gimple.h"
#include "cgraph.h"
#include "output.h"
#include "flags.h"
#include "timevar.h"
#include "diagnostic.h"
#include "langhooks.h"

/* Debugging function for postorder and inorder code. NOTE is a string
   that is printed before the nodes are printed.  ORDER is an array of
   cgraph_nodes that has COUNT useful nodes in it.  */

void
ipa_print_order (FILE* out,
		 const char * note,
		 struct cgraph_node** order,
		 int count)
{
  int i;
  fprintf (out, "\n\n ordered call graph: %s\n", note);

  for (i = count - 1; i >= 0; i--)
    dump_cgraph_node(dump_file, order[i]);
  fprintf (out, "\n");
  fflush(out);
}


struct searchc_env {
  struct cgraph_node **stack;
  int stack_size;
  struct cgraph_node **result;
  int order_pos;
  splay_tree nodes_marked_new;
  bool reduce;
  int count;
};

/* This is an implementation of Tarjan's strongly connected region
   finder as reprinted in Aho Hopcraft and Ullman's The Design and
   Analysis of Computer Programs (1975) pages 192-193.  This version
   has been customized for cgraph_nodes.  The env parameter is because
   it is recursive and there are no nested functions here.  This
   function should only be called from itself or
   ipa_reduced_postorder.  ENV is a stack env and would be
   unnecessary if C had nested functions.  V is the node to start
   searching from.  */

static void
searchc (struct searchc_env* env, struct cgraph_node *v,
	 bool (*ignore_edge) (struct cgraph_edge *))
{
  struct cgraph_edge *edge;
  struct ipa_dfs_info *v_info = (struct ipa_dfs_info *) v->aux;

  /* mark node as old */
  v_info->new_node = false;
  splay_tree_remove (env->nodes_marked_new, v->uid);

  v_info->dfn_number = env->count;
  v_info->low_link = env->count;
  env->count++;
  env->stack[(env->stack_size)++] = v;
  v_info->on_stack = true;

  for (edge = v->callees; edge; edge = edge->next_callee)
    {
      struct ipa_dfs_info * w_info;
      struct cgraph_node *w = edge->callee;

      if (ignore_edge && ignore_edge (edge))
        continue;

      if (w->aux && cgraph_function_body_availability (edge->callee) > AVAIL_OVERWRITABLE)
	{
	  w_info = (struct ipa_dfs_info *) w->aux;
	  if (w_info->new_node)
	    {
	      searchc (env, w, ignore_edge);
	      v_info->low_link =
		(v_info->low_link < w_info->low_link) ?
		v_info->low_link : w_info->low_link;
	    }
	  else
	    if ((w_info->dfn_number < v_info->dfn_number)
		&& (w_info->on_stack))
	      v_info->low_link =
		(w_info->dfn_number < v_info->low_link) ?
		w_info->dfn_number : v_info->low_link;
	}
    }


  if (v_info->low_link == v_info->dfn_number)
    {
      struct cgraph_node *last = NULL;
      struct cgraph_node *x;
      struct ipa_dfs_info *x_info;
      do {
	x = env->stack[--(env->stack_size)];
	x_info = (struct ipa_dfs_info *) x->aux;
	x_info->on_stack = false;

	if (env->reduce)
	  {
	    x_info->next_cycle = last;
	    last = x;
	  }
	else
	  env->result[env->order_pos++] = x;
      }
      while (v != x);
      if (env->reduce)
	env->result[env->order_pos++] = v;
    }
}

/* Topsort the call graph by caller relation.  Put the result in ORDER.

   The REDUCE flag is true if you want the cycles reduced to single nodes.  Set
   ALLOW_OVERWRITABLE if nodes with such availability should be included.
   IGNORE_EDGE, if non-NULL is a hook that may make some edges insignificant
   for the topological sort.   */

int
ipa_reduced_postorder (struct cgraph_node **order,
		       bool reduce, bool allow_overwritable,
		       bool (*ignore_edge) (struct cgraph_edge *))
{
  struct cgraph_node *node;
  struct searchc_env env;
  splay_tree_node result;
  env.stack = XCNEWVEC (struct cgraph_node *, cgraph_n_nodes);
  env.stack_size = 0;
  env.result = order;
  env.order_pos = 0;
  env.nodes_marked_new = splay_tree_new (splay_tree_compare_ints, 0, 0);
  env.count = 1;
  env.reduce = reduce;

  for (node = cgraph_nodes; node; node = node->next)
    {
      enum availability avail = cgraph_function_body_availability (node);

      if (avail > AVAIL_OVERWRITABLE
	  || (allow_overwritable
	      && (avail == AVAIL_OVERWRITABLE)))
	{
	  /* Reuse the info if it is already there.  */
	  struct ipa_dfs_info *info = (struct ipa_dfs_info *) node->aux;
	  if (!info)
	    info = XCNEW (struct ipa_dfs_info);
	  info->new_node = true;
	  info->on_stack = false;
	  info->next_cycle = NULL;
	  node->aux = info;

	  splay_tree_insert (env.nodes_marked_new,
			     (splay_tree_key)node->uid,
			     (splay_tree_value)node);
	}
      else
	node->aux = NULL;
    }
  result = splay_tree_min (env.nodes_marked_new);
  while (result)
    {
      node = (struct cgraph_node *)result->value;
      searchc (&env, node, ignore_edge);
      result = splay_tree_min (env.nodes_marked_new);
    }
  splay_tree_delete (env.nodes_marked_new);
  free (env.stack);

  return env.order_pos;
}

/* Deallocate all ipa_dfs_info structures pointed to by the aux pointer of call
   graph nodes.  */

void
ipa_free_postorder_info (void)
{
  struct cgraph_node *node;
  for (node = cgraph_nodes; node; node = node->next)
    {
      /* Get rid of the aux information.  */
      if (node->aux)
	{
	  free (node->aux);
	  node->aux = NULL;
	}
    }
}

/* Fill array order with all nodes with output flag set in the reverse
   topological order.  Return the number of elements in the array.  */

int
ipa_reverse_postorder (struct cgraph_node **order)
{
  struct cgraph_node *node, *node2;
  int stack_size = 0;
  int order_pos = 0;
  struct cgraph_edge *edge, last;
  int pass;

  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 inline functions.  */
  for (node = cgraph_nodes; node; node = node->next)
    node->aux = NULL;
  for (pass = 0; pass < 2; pass++)
    for (node = cgraph_nodes; node; node = node->next)
      if (!node->aux
	  && (pass
	      || (!node->address_taken
		  && !node->global.inlined_to
		  && !cgraph_only_called_directly_p (node))))
	{
	  node2 = node;
	  if (!node->callers)
	    node->aux = &last;
	  else
	    node->aux = node->callers;
	  while (node2)
	    {
	      while (node2->aux != &last)
		{
		  edge = (struct cgraph_edge *) node2->aux;
		  if (edge->next_caller)
		    node2->aux = edge->next_caller;
		  else
		    node2->aux = &last;
		  /* Break possible cycles involving always-inline
		     functions by ignoring edges from always-inline
		     functions to non-always-inline functions.  */
		  if (DECL_DISREGARD_INLINE_LIMITS (edge->caller->decl)
		      && !DECL_DISREGARD_INLINE_LIMITS (edge->callee->decl))
		    continue;
		  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;
}



/* Given a memory reference T, will return the variable at the bottom
   of the access.  Unlike get_base_address, this will recurse thru
   INDIRECT_REFS.  */

tree
get_base_var (tree t)
{
  while (!SSA_VAR_P (t)
	 && (!CONSTANT_CLASS_P (t))
	 && TREE_CODE (t) != LABEL_DECL
	 && TREE_CODE (t) != FUNCTION_DECL
	 && TREE_CODE (t) != CONST_DECL
	 && TREE_CODE (t) != CONSTRUCTOR)
    {
      t = TREE_OPERAND (t, 0);
    }
  return t;
}