/* Callgraph construction.
   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008
   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 "toplev.h"
#include "gcov-io.h"
#include "coverage.h"
#include "tree-pass.h"
#include "tree-sample-profile.h"

/* Walk tree and record all calls and references to functions/variables.
   Called via walk_tree: TP is pointer to tree to be examined.  */

static tree
record_reference (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
{
  tree t = *tp;
  tree decl;

  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)
	{
	  cgraph_mark_needed_node (cgraph_node (decl));
	  cgraph_mark_address_taken (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;
}

/* Give initial reasons why inlining would fail on all calls from
   NODE.  Those get either nullified or usually overwritten by more precise
   reason later.  */

static void
initialize_inline_failed (struct cgraph_node *node)
{
  struct cgraph_edge *e;

  for (e = node->callers; e; e = e->next_caller)
    {
      gcc_assert (!e->callee->global.inlined_to);
      gcc_assert (e->inline_failed);
      if (node->local.redefined_extern_inline)
	e->inline_failed = N_("redefined extern inline functions are not "
			   "considered for inlining");
      else if (!node->local.inlinable)
	e->inline_failed = N_("function not inlinable");
      else if (!e->call_stmt)
        {
          /* Artifcial edge.  */
          gcc_assert (L_IPO_COMP_MODE
                      && cgraph_is_fake_indirect_call_edge (e));
          e->inline_failed = N_("artificial edge");
        }
      else if (gimple_call_cannot_inline_p (e->call_stmt))
	e->inline_failed = N_("mismatched arguments");
      else
	e->inline_failed = N_("function not considered for inlining");
    }
}

/* 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 (basic_block bb)
{
  int entry_freq = ENTRY_BLOCK_PTR->frequency;
  int freq = bb->frequency;

  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;
}


bool cgraph_need_artificial_indirect_call_edges = true;

/* Return true if E is a fake indirect call edge.  */

bool 
cgraph_is_fake_indirect_call_edge (struct cgraph_edge *e)
{
 return !e->call_stmt && e->indirect_call;
}

/* Add fake cgraph edges from NODE to its indirect call callees
   using profile data.  */

static void
add_fake_indirect_call_edges (struct cgraph_node *node)
{
  unsigned n_counts, i;
  gcov_type *ic_counts;

  /* Enable this only for LIPO for now.  */
  if (!L_IPO_COMP_MODE)
    return;

  if (!cgraph_need_artificial_indirect_call_edges)
    return;

  ic_counts
      = get_coverage_counts_no_warn (DECL_STRUCT_FUNCTION (node->decl),
                                     GCOV_COUNTER_ICALL_TOPNV, &n_counts);

  if (!ic_counts && !flag_sample_profile)
    return;

  /* For sample profile, we find the th indirect callees by its names.  */
  if (flag_sample_profile)
    {
      struct sample_indirect_call *ic =
          sp_get_indirect_calls (cgraph_node_name (node));
      if (!ic)
        return;
      for (i = 0; i < ic->num_values; i++)
        {
          struct cgraph_node *callee = find_func_by_name (ic->targets[i]);
          if (callee)
            {
              struct cgraph_edge *e;
              tree decl = callee->decl;
              e = cgraph_create_edge (node, cgraph_real_node (decl), NULL,
                                      ic->count[i], 0, 0);
              e->indirect_call = 1;
            }
        }
      return;
    }

  gcc_assert ((n_counts % GCOV_ICALL_TOPN_NCOUNTS) == 0);

   /* After the early_inline_1 before value profile transformation, 
      functions that are indirect call targets may have their bodies
      removed (extern inline functions or functions from aux modules,
      functions in comdat etc) if all direct callsites are inlined. This
      will lead to missing inline opportunities after profile based 
      indirect call promotion. The solution is to add fake edges to
      indirect call targets. Note that such edges are not associated 
      with actual indirect call sites because it is not possible to 
      reliably match pre-early-inline indirect callsites with indirect
      call profile counters which are from post-early inline function body.  */

  for (i = 0; i < n_counts;
       i += GCOV_ICALL_TOPN_NCOUNTS, ic_counts += GCOV_ICALL_TOPN_NCOUNTS)
    {
      gcov_type val1, val2, count1, count2;
      struct cgraph_node *direct_call1 = 0, *direct_call2 = 0;

      val1 = ic_counts[1];
      count1 = ic_counts[2];
      val2 = ic_counts[3];
      count2 = ic_counts[4];

      if (val1 == 0 || count1 == 0)
        continue;

      direct_call1 = find_func_by_global_id (val1);
      if (direct_call1)
        {
          struct cgraph_edge *e;
          tree decl = direct_call1->decl;
          e = cgraph_create_edge (node, cgraph_real_node (decl), NULL,
                                  count1, 0, 0);
          e->indirect_call = 1;
        }

      if (val2 == 0 || count2 == 0)
        continue;
      direct_call2 = find_func_by_global_id (val2);
      if (direct_call2)
        {
          struct cgraph_edge *e;
          tree decl = direct_call2->decl;
          e = cgraph_create_edge (node, cgraph_real_node (decl), NULL,
                                  count2, 0, 0);
          e->indirect_call = 1;
        }
    }
}

/* This can be implemented as an IPA pass that must be first one 
   before any unreachable node elimination. */

void
cgraph_add_fake_indirect_call_edges (void)
{
  struct cgraph_node *node;

  /* Enable this only for LIPO for now.  */
  if (!L_IPO_COMP_MODE)
    return;

  for (node = cgraph_nodes; node; node = node->next)
    {
      if (node->analyzed && (node->needed || node->reachable))
        add_fake_indirect_call_edges (node);
    }
}

/* 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_real_node (decl), stmt,
				bb->count, compute_call_stmt_bb_frequency (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);
  initialize_inline_failed (node);
  return 0;
}

struct gimple_opt_pass pass_build_cgraph_edges =
{
 {
  GIMPLE_PASS,
  NULL,					/* name */
  NULL,					/* gate */
  build_cgraph_edges,			/* execute */
  NULL,					/* sub */
  NULL,					/* next */
  0,					/* static_pass_number */
  0,					/* tv_id */
  PROP_cfg,				/* properties_required */
  0,					/* properties_provided */
  0,					/* properties_destroyed */
  0,					/* todo_flags_start */
  0					/* todo_flags_finish */
 }
};

/* Record references to functions and other variables present in the
   initial value of DECL, a variable.  */

void
record_references_in_initializer (tree decl)
{
  struct pointer_set_t *visited_nodes = pointer_set_create ();
  walk_tree (&DECL_INITIAL (decl), record_reference, NULL, 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;
  node->max_bb_count = 0;

  FOR_EACH_BB (bb)
    {
      if (bb->count > node->max_bb_count)
	node->max_bb_count = bb->count;
      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_real_node (decl), stmt,
				bb->count, compute_call_stmt_bb_frequency (bb),
				bb->loop_depth);
	}
    }

  add_fake_indirect_call_edges (node);

  initialize_inline_failed (node);
  gcc_assert (!node->global.inlined_to);
  return 0;
}

struct gimple_opt_pass pass_rebuild_cgraph_edges =
{
 {
  GIMPLE_PASS,
  NULL,					/* name */
  NULL,					/* gate */
  rebuild_cgraph_edges,			/* execute */
  NULL,					/* sub */
  NULL,					/* next */
  0,					/* static_pass_number */
  0,					/* tv_id */
  PROP_cfg,				/* properties_required */
  0,					/* properties_provided */
  0,					/* properties_destroyed */
  0,					/* todo_flags_start */
  0,					/* todo_flags_finish */
 }
};