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/* Data flow functions for trees.

   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009

   Free Software Foundation, Inc.

   Contributed by Diego Novillo <dnovillo@redhat.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 "hashtab.h"

#include "pointer-set.h"

#include "tree.h"

#include "rtl.h"

#include "tm_p.h"

#include "hard-reg-set.h"

#include "basic-block.h"

#include "output.h"

#include "timevar.h"

#include "expr.h"

#include "ggc.h"

#include "langhooks.h"

#include "flags.h"

#include "function.h"

#include "diagnostic.h"

#include "tree-dump.h"

#include "gimple.h"

#include "tree-flow.h"

#include "tree-inline.h"

#include "tree-pass.h"

#include "convert.h"

#include "params.h"

#include "cgraph.h"

/* Build and maintain data flow information for trees.  */

/* Counters used to display DFA and SSA statistics.  */

struct dfa_stats_d

{

  long num_var_anns;

  long num_defs;

  long num_uses;

  long num_phis;

  long num_phi_args;

  size_t max_num_phi_args;

  long num_vdefs;

  long num_vuses;

};

/* Local functions.  */

static void collect_dfa_stats (struct dfa_stats_d *);

static tree find_vars_r (tree *, int *, void *);

/*---------------------------------------------------------------------------

                        Dataflow analysis (DFA) routines

---------------------------------------------------------------------------*/

/* Find all the variables referenced in the function.  This function

   builds the global arrays REFERENCED_VARS and CALL_CLOBBERED_VARS.

   Note that this function does not look for statement operands, it simply

   determines what variables are referenced in the program and detects

   various attributes for each variable used by alias analysis and the

   optimizer.  */

static unsigned int

find_referenced_vars (void)

{

  basic_block bb;

  gimple_stmt_iterator si;

  FOR_EACH_BB (bb)

    {

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

        {

          gimple stmt = gsi_stmt (si);

          if (is_gimple_debug (stmt))

            continue;

          find_referenced_vars_in (gsi_stmt (si));

        }

      for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))

        find_referenced_vars_in (gsi_stmt (si));

    }

  return 0;

}

struct gimple_opt_pass pass_referenced_vars =

{

 {

  GIMPLE_PASS,

  "*referenced_vars",                   /* name */

  NULL,                                 /* gate */

  find_referenced_vars,                 /* execute */

  NULL,                                 /* sub */

  NULL,                                 /* next */

  0,                                     /* static_pass_number */

  TV_FIND_REFERENCED_VARS,              /* tv_id */

  PROP_gimple_leh | PROP_cfg,           /* properties_required */

  PROP_referenced_vars,                 /* properties_provided */

  0,                                     /* properties_destroyed */

  TODO_dump_func,                       /* todo_flags_start */

  TODO_dump_func                        /* todo_flags_finish */

 }

};

/*---------------------------------------------------------------------------

                            Manage annotations

---------------------------------------------------------------------------*/

/* Create a new annotation for a _DECL node T.  */

var_ann_t

create_var_ann (tree t)

{

  var_ann_t ann;

  gcc_assert (t);

  gcc_assert (TREE_CODE (t) == VAR_DECL

              || TREE_CODE (t) == PARM_DECL

              || TREE_CODE (t) == RESULT_DECL);

  ann = GGC_CNEW (struct var_ann_d);

  *DECL_VAR_ANN_PTR (t) = ann;

  return ann;

}

/* Renumber all of the gimple stmt uids.  */

void

renumber_gimple_stmt_uids (void)

{

  basic_block bb;

  set_gimple_stmt_max_uid (cfun, 0);

  FOR_ALL_BB (bb)

    {

      gimple_stmt_iterator bsi;

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

        {

          gimple stmt = gsi_stmt (bsi);

          gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));

        }

    }

}

/* Like renumber_gimple_stmt_uids, but only do work on the basic blocks

   in BLOCKS, of which there are N_BLOCKS.  Also renumbers PHIs.  */

void

renumber_gimple_stmt_uids_in_blocks (basic_block *blocks, int n_blocks)

{

  int i;

  set_gimple_stmt_max_uid (cfun, 0);

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

    {

      basic_block bb = blocks[i];

      gimple_stmt_iterator bsi;

      for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))

        {

          gimple stmt = gsi_stmt (bsi);

          gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));

        }

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

        {

          gimple stmt = gsi_stmt (bsi);

          gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));

        }

    }

}

/* Build a temporary.  Make sure and register it to be renamed.  */

tree

make_rename_temp (tree type, const char *prefix)

{

  tree t = create_tmp_var (type, prefix);

  if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE

      || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)

    DECL_GIMPLE_REG_P (t) = 1;

  if (gimple_referenced_vars (cfun))

    {

      add_referenced_var (t);

      mark_sym_for_renaming (t);

    }

  return t;

}

/*---------------------------------------------------------------------------

                              Debugging functions

---------------------------------------------------------------------------*/

/* Dump the list of all the referenced variables in the current function to

   FILE.  */

void

dump_referenced_vars (FILE *file)

{

  tree var;

  referenced_var_iterator rvi;

  fprintf (file, "\nReferenced variables in %s: %u\n\n",

           get_name (current_function_decl), (unsigned) num_referenced_vars);

  FOR_EACH_REFERENCED_VAR (var, rvi)

    {

      fprintf (file, "Variable: ");

      dump_variable (file, var);

    }

  fprintf (file, "\n");

}

/* Dump the list of all the referenced variables to stderr.  */

void

debug_referenced_vars (void)

{

  dump_referenced_vars (stderr);

}

/* Dump variable VAR and its may-aliases to FILE.  */

void

dump_variable (FILE *file, tree var)

{

  var_ann_t ann;

  if (TREE_CODE (var) == SSA_NAME)

    {

      if (POINTER_TYPE_P (TREE_TYPE (var)))

        dump_points_to_info_for (file, var);

      var = SSA_NAME_VAR (var);

    }

  if (var == NULL_TREE)

    {

      fprintf (file, "<nil>");

      return;

    }

  print_generic_expr (file, var, dump_flags);

  ann = var_ann (var);

  fprintf (file, ", UID D.%u", (unsigned) DECL_UID (var));

  fprintf (file, ", ");

  print_generic_expr (file, TREE_TYPE (var), dump_flags);

  if (TREE_ADDRESSABLE (var))

    fprintf (file, ", is addressable");

  if (is_global_var (var))

    fprintf (file, ", is global");

  if (TREE_THIS_VOLATILE (var))

    fprintf (file, ", is volatile");

  if (is_call_clobbered (var))

    fprintf (file, ", call clobbered");

  else if (is_call_used (var))

    fprintf (file, ", call used");

  if (ann && ann->noalias_state == NO_ALIAS)

    fprintf (file, ", NO_ALIAS (does not alias other NO_ALIAS symbols)");

  else if (ann && ann->noalias_state == NO_ALIAS_GLOBAL)

    fprintf (file, ", NO_ALIAS_GLOBAL (does not alias other NO_ALIAS symbols"

                   " and global vars)");

  else if (ann && ann->noalias_state == NO_ALIAS_ANYTHING)

    fprintf (file, ", NO_ALIAS_ANYTHING (does not alias any other symbols)");

  if (cfun && gimple_default_def (cfun, var))

    {

      fprintf (file, ", default def: ");

      print_generic_expr (file, gimple_default_def (cfun, var), dump_flags);

    }

  if (DECL_INITIAL (var))

    {

      fprintf (file, ", initial: ");

      print_generic_expr (file, DECL_INITIAL (var), dump_flags);

    }

  fprintf (file, "\n");

}

/* Dump variable VAR and its may-aliases to stderr.  */

void

debug_variable (tree var)

{

  dump_variable (stderr, var);

}

/* Dump various DFA statistics to FILE.  */

void

dump_dfa_stats (FILE *file)

{

  struct dfa_stats_d dfa_stats;

  unsigned long size, total = 0;

  const char * const fmt_str   = "%-30s%-13s%12s\n";

  const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";

  const char * const fmt_str_3 = "%-43s%11lu%c\n";

  const char *funcname

    = lang_hooks.decl_printable_name (current_function_decl, 2);

  collect_dfa_stats (&dfa_stats);

  fprintf (file, "\nDFA Statistics for %s\n\n", funcname);

  fprintf (file, "---------------------------------------------------------\n");

  fprintf (file, fmt_str, "", "  Number of  ", "Memory");

  fprintf (file, fmt_str, "", "  instances  ", "used ");

  fprintf (file, "---------------------------------------------------------\n");

  size = num_referenced_vars * sizeof (tree);

  total += size;

  fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars,

           SCALE (size), LABEL (size));

  size = dfa_stats.num_var_anns * sizeof (struct var_ann_d);

  total += size;

  fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns,

           SCALE (size), LABEL (size));

  size = dfa_stats.num_uses * sizeof (tree *);

  total += size;

  fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,

           SCALE (size), LABEL (size));

  size = dfa_stats.num_defs * sizeof (tree *);

  total += size;

  fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,

           SCALE (size), LABEL (size));

  size = dfa_stats.num_vuses * sizeof (tree *);

  total += size;

  fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,

           SCALE (size), LABEL (size));

  size = dfa_stats.num_vdefs * sizeof (tree *);

  total += size;

  fprintf (file, fmt_str_1, "VDEF operands", dfa_stats.num_vdefs,

           SCALE (size), LABEL (size));

  size = dfa_stats.num_phis * sizeof (struct gimple_statement_phi);

  total += size;

  fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,

           SCALE (size), LABEL (size));

  size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);

  total += size;

  fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,

           SCALE (size), LABEL (size));

  fprintf (file, "---------------------------------------------------------\n");

  fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),

           LABEL (total));

  fprintf (file, "---------------------------------------------------------\n");

  fprintf (file, "\n");

  if (dfa_stats.num_phis)

    fprintf (file, "Average number of arguments per PHI node: %.1f (max: %ld)\n",

             (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,

             (long) dfa_stats.max_num_phi_args);

  fprintf (file, "\n");

}

/* Dump DFA statistics on stderr.  */

void

debug_dfa_stats (void)

{

  dump_dfa_stats (stderr);

}

/* Collect DFA statistics and store them in the structure pointed to by

   DFA_STATS_P.  */

static void

collect_dfa_stats (struct dfa_stats_d *dfa_stats_p ATTRIBUTE_UNUSED)

{

  basic_block bb;

  referenced_var_iterator vi;

  tree var;

  gcc_assert (dfa_stats_p);

  memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));

  /* Count all the variable annotations.  */

  FOR_EACH_REFERENCED_VAR (var, vi)

    if (var_ann (var))

      dfa_stats_p->num_var_anns++;

  /* Walk all the statements in the function counting references.  */

  FOR_EACH_BB (bb)

    {

      gimple_stmt_iterator si;

      for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))

        {

          gimple phi = gsi_stmt (si);

          dfa_stats_p->num_phis++;

          dfa_stats_p->num_phi_args += gimple_phi_num_args (phi);

          if (gimple_phi_num_args (phi) > dfa_stats_p->max_num_phi_args)

            dfa_stats_p->max_num_phi_args = gimple_phi_num_args (phi);

        }

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

        {

          gimple stmt = gsi_stmt (si);

          dfa_stats_p->num_defs += NUM_SSA_OPERANDS (stmt, SSA_OP_DEF);

          dfa_stats_p->num_uses += NUM_SSA_OPERANDS (stmt, SSA_OP_USE);

          dfa_stats_p->num_vdefs += gimple_vdef (stmt) ? 1 : 0;

          dfa_stats_p->num_vuses += gimple_vuse (stmt) ? 1 : 0;

        }

    }

}

/*---------------------------------------------------------------------------

                             Miscellaneous helpers

---------------------------------------------------------------------------*/

/* Callback for walk_tree.  Used to collect variables referenced in

   the function.  */

static tree

find_vars_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)

{

  /* If we are reading the lto info back in, we need to rescan the

     referenced vars.  */

  if (TREE_CODE (*tp) == SSA_NAME)

    add_referenced_var (SSA_NAME_VAR (*tp));

  /* If T is a regular variable that the optimizers are interested

     in, add it to the list of variables.  */

  else if (SSA_VAR_P (*tp))

    add_referenced_var (*tp);

  /* Type, _DECL and constant nodes have no interesting children.

     Ignore them.  */

  else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp))

    *walk_subtrees = 0;

  return NULL_TREE;

}

/* Find referenced variables in STMT.  In contrast with

   find_new_referenced_vars, this function will not mark newly found

   variables for renaming.  */

void

find_referenced_vars_in (gimple stmt)

{

  size_t i;

  if (gimple_code (stmt) != GIMPLE_PHI)

    {

      for (i = 0; i < gimple_num_ops (stmt); i++)

        walk_tree (gimple_op_ptr (stmt, i), find_vars_r, NULL, NULL);

    }

  else

    {

      walk_tree (gimple_phi_result_ptr (stmt), find_vars_r, NULL, NULL);

      for (i = 0; i < gimple_phi_num_args (stmt); i++)

        {

          tree arg = gimple_phi_arg_def (stmt, i);

          walk_tree (&arg, find_vars_r, NULL, NULL);

        }

    }

}

/* Lookup UID in the referenced_vars hashtable and return the associated

   variable.  */

tree

referenced_var_lookup (unsigned int uid)

{

  tree h;

  struct tree_decl_minimal in;

  in.uid = uid;

  h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);

  gcc_assert (h || uid == 0);

  return h;

}

/* Check if TO is in the referenced_vars hash table and insert it if not.

   Return true if it required insertion.  */

bool

referenced_var_check_and_insert (tree to)

{

  tree h, *loc;

  struct tree_decl_minimal in;

  unsigned int uid = DECL_UID (to);

  in.uid = uid;

  h = (tree) htab_find_with_hash (gimple_referenced_vars (cfun), &in, uid);

  if (h)

    {

      /* DECL_UID has already been entered in the table.  Verify that it is

         the same entry as TO.  See PR 27793.  */

      gcc_assert (h == to);

      return false;

    }

  loc = (tree *) htab_find_slot_with_hash (gimple_referenced_vars (cfun),

                                           &in, uid, INSERT);

  *loc = to;

  return true;

}

/* Lookup VAR UID in the default_defs hashtable and return the associated

   variable.  */

tree

gimple_default_def (struct function *fn, tree var)

{

  struct tree_decl_minimal ind;

  struct tree_ssa_name in;

  gcc_assert (SSA_VAR_P (var));

  in.var = (tree)&ind;

  ind.uid = DECL_UID (var);

  return (tree) htab_find_with_hash (DEFAULT_DEFS (fn), &in, DECL_UID (var));

}

/* Insert the pair VAR's UID, DEF into the default_defs hashtable.  */

void

set_default_def (tree var, tree def)

{

  struct tree_decl_minimal ind;

  struct tree_ssa_name in;

  void **loc;

  gcc_assert (SSA_VAR_P (var));

  in.var = (tree)&ind;

  ind.uid = DECL_UID (var);

  if (!def)

    {

      loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,

            DECL_UID (var), INSERT);

      gcc_assert (*loc);

      htab_remove_elt (DEFAULT_DEFS (cfun), *loc);

      return;

    }

  gcc_assert (TREE_CODE (def) == SSA_NAME && SSA_NAME_VAR (def) == var);

  loc = htab_find_slot_with_hash (DEFAULT_DEFS (cfun), &in,

                                  DECL_UID (var), INSERT);

  /* Default definition might be changed by tail call optimization.  */

  if (*loc)

    SSA_NAME_IS_DEFAULT_DEF (*(tree *) loc) = false;

  *(tree *) loc = def;

   /* Mark DEF as the default definition for VAR.  */

   SSA_NAME_IS_DEFAULT_DEF (def) = true;

}

/* Add VAR to the list of referenced variables if it isn't already there.  */

bool

add_referenced_var (tree var)

{

  get_var_ann (var);

  gcc_assert (DECL_P (var));

  /* Insert VAR into the referenced_vars has table if it isn't present.  */

  if (referenced_var_check_and_insert (var))

    {

      /* Scan DECL_INITIAL for pointer variables as they may contain

         address arithmetic referencing the address of other

         variables.  As we are only interested in directly referenced

         globals or referenced locals restrict this to initializers

         than can refer to local variables.  */

      if (DECL_INITIAL (var)

          && DECL_CONTEXT (var) == current_function_decl)

        walk_tree (&DECL_INITIAL (var), find_vars_r, NULL, 0);

      return true;

    }

  return false;

}

/* Remove VAR from the list.  */

void

remove_referenced_var (tree var)

{

  var_ann_t v_ann;

  struct tree_decl_minimal in;

  void **loc;

  unsigned int uid = DECL_UID (var);

  /* Preserve var_anns of globals.  */

  if (!is_global_var (var)

      && (v_ann = var_ann (var)))

    {

      ggc_free (v_ann);

      *DECL_VAR_ANN_PTR (var) = NULL;

    }

  gcc_assert (DECL_P (var));

  in.uid = uid;

  loc = htab_find_slot_with_hash (gimple_referenced_vars (cfun), &in, uid,

                                  NO_INSERT);

  htab_clear_slot (gimple_referenced_vars (cfun), loc);

}

/* Return the virtual variable associated to the non-scalar variable VAR.  */

tree

get_virtual_var (tree var)

{

  STRIP_NOPS (var);

  if (TREE_CODE (var) == SSA_NAME)

    var = SSA_NAME_VAR (var);

  while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR

         || handled_component_p (var))

    var = TREE_OPERAND (var, 0);

  /* Treating GIMPLE registers as virtual variables makes no sense.

     Also complain if we couldn't extract a _DECL out of the original

     expression.  */

  gcc_assert (SSA_VAR_P (var));

  gcc_assert (!is_gimple_reg (var));

  return var;

}

/* Mark all the naked symbols in STMT for SSA renaming.  */

void

mark_symbols_for_renaming (gimple stmt)

{

  tree op;

  ssa_op_iter iter;

  update_stmt (stmt);

  /* Mark all the operands for renaming.  */

  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_OPERANDS)

    if (DECL_P (op))

      mark_sym_for_renaming (op);

}

/* Find all variables within the gimplified statement that were not

   previously visible to the function and add them to the referenced

   variables list.  */

static tree

find_new_referenced_vars_1 (tree *tp, int *walk_subtrees,