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/* Single entry single exit control flow regions.

   Copyright (C) 2008, 2009, 2010, 2011

   Free Software Foundation, Inc.

   Contributed by Jan Sjodin <jan.sjodin@amd.com> and

   Sebastian Pop <sebastian.pop@amd.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 "tree-pretty-print.h"

#include "tree-flow.h"

#include "cfgloop.h"

#include "tree-chrec.h"

#include "tree-data-ref.h"

#include "tree-scalar-evolution.h"

#include "tree-pass.h"

#include "value-prof.h"

#include "sese.h"

/* Print to stderr the element ELT.  */

static void

debug_rename_elt (rename_map_elt elt)

{

  fprintf (stderr, "(");

  print_generic_expr (stderr, elt->old_name, 0);

  fprintf (stderr, ", ");

  print_generic_expr (stderr, elt->expr, 0);

  fprintf (stderr, ")\n");

}

/* Helper function for debug_rename_map.  */

static int

debug_rename_map_1 (void **slot, void *s ATTRIBUTE_UNUSED)

{

  struct rename_map_elt_s *entry = (struct rename_map_elt_s *) *slot;

  debug_rename_elt (entry);

  return 1;

}

/* Print to stderr all the elements of RENAME_MAP.  */

DEBUG_FUNCTION void

debug_rename_map (htab_t rename_map)

{

  htab_traverse (rename_map, debug_rename_map_1, NULL);

}

/* Computes a hash function for database element ELT.  */

hashval_t

rename_map_elt_info (const void *elt)

{

  return SSA_NAME_VERSION (((const struct rename_map_elt_s *) elt)->old_name);

}

/* Compares database elements E1 and E2.  */

int

eq_rename_map_elts (const void *e1, const void *e2)

{

  const struct rename_map_elt_s *elt1 = (const struct rename_map_elt_s *) e1;

  const struct rename_map_elt_s *elt2 = (const struct rename_map_elt_s *) e2;

  return (elt1->old_name == elt2->old_name);

}

/* Print to stderr the element ELT.  */

static void

debug_ivtype_elt (ivtype_map_elt elt)

{

  fprintf (stderr, "(%s, ", elt->cloog_iv);

  print_generic_expr (stderr, elt->type, 0);

  fprintf (stderr, ")\n");

}

/* Helper function for debug_ivtype_map.  */

static int

debug_ivtype_map_1 (void **slot, void *s ATTRIBUTE_UNUSED)

{

  struct ivtype_map_elt_s *entry = (struct ivtype_map_elt_s *) *slot;

  debug_ivtype_elt (entry);

  return 1;

}

/* Print to stderr all the elements of MAP.  */

DEBUG_FUNCTION void

debug_ivtype_map (htab_t map)

{

  htab_traverse (map, debug_ivtype_map_1, NULL);

}

/* Computes a hash function for database element ELT.  */

hashval_t

ivtype_map_elt_info (const void *elt)

{

  return htab_hash_pointer (((const struct ivtype_map_elt_s *) elt)->cloog_iv);

}

/* Compares database elements E1 and E2.  */

int

eq_ivtype_map_elts (const void *e1, const void *e2)

{

  const struct ivtype_map_elt_s *elt1 = (const struct ivtype_map_elt_s *) e1;

  const struct ivtype_map_elt_s *elt2 = (const struct ivtype_map_elt_s *) e2;

  return (elt1->cloog_iv == elt2->cloog_iv);

}

/* Record LOOP as occuring in REGION.  */

static void

sese_record_loop (sese region, loop_p loop)

{

  if (sese_contains_loop (region, loop))

    return;

  bitmap_set_bit (SESE_LOOPS (region), loop->num);

  VEC_safe_push (loop_p, heap, SESE_LOOP_NEST (region), loop);

}

/* Build the loop nests contained in REGION.  Returns true when the

   operation was successful.  */

void

build_sese_loop_nests (sese region)

{

  unsigned i;

  basic_block bb;

  struct loop *loop0, *loop1;

  FOR_EACH_BB (bb)

    if (bb_in_sese_p (bb, region))

      {

        struct loop *loop = bb->loop_father;

        /* Only add loops if they are completely contained in the SCoP.  */

        if (loop->header == bb

            && bb_in_sese_p (loop->latch, region))

          sese_record_loop (region, loop);

      }

  /* Make sure that the loops in the SESE_LOOP_NEST are ordered.  It

     can be the case that an inner loop is inserted before an outer

     loop.  To avoid this, semi-sort once.  */

  FOR_EACH_VEC_ELT (loop_p, SESE_LOOP_NEST (region), i, loop0)

    {

      if (VEC_length (loop_p, SESE_LOOP_NEST (region)) == i + 1)

        break;

      loop1 = VEC_index (loop_p, SESE_LOOP_NEST (region), i + 1);

      if (loop0->num > loop1->num)

        {

          VEC_replace (loop_p, SESE_LOOP_NEST (region), i, loop1);

          VEC_replace (loop_p, SESE_LOOP_NEST (region), i + 1, loop0);

        }

    }

}

/* For a USE in BB, if BB is outside REGION, mark the USE in the

   LIVEOUTS set.  */

static void

sese_build_liveouts_use (sese region, bitmap liveouts, basic_block bb,

                         tree use)

{

  unsigned ver;

  basic_block def_bb;

  if (TREE_CODE (use) != SSA_NAME)

    return;

  ver = SSA_NAME_VERSION (use);

  def_bb = gimple_bb (SSA_NAME_DEF_STMT (use));

  if (!def_bb

      || !bb_in_sese_p (def_bb, region)

      || bb_in_sese_p (bb, region))

    return;

  bitmap_set_bit (liveouts, ver);

}

/* Marks for rewrite all the SSA_NAMES defined in REGION and that are

   used in BB that is outside of the REGION.  */

static void

sese_build_liveouts_bb (sese region, bitmap liveouts, basic_block bb)

{

  gimple_stmt_iterator bsi;

  edge e;

  edge_iterator ei;

  ssa_op_iter iter;

  use_operand_p use_p;

  FOR_EACH_EDGE (e, ei, bb->succs)

    for (bsi = gsi_start_phis (e->dest); !gsi_end_p (bsi); gsi_next (&bsi))

      sese_build_liveouts_use (region, liveouts, bb,

                               PHI_ARG_DEF_FROM_EDGE (gsi_stmt (bsi), e));

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

    {

      gimple stmt = gsi_stmt (bsi);

      if (is_gimple_debug (stmt))

        continue;

      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)

        sese_build_liveouts_use (region, liveouts, bb, USE_FROM_PTR (use_p));

    }

}

/* For a USE in BB, return true if BB is outside REGION and it's not

   in the LIVEOUTS set.  */

static bool

sese_bad_liveouts_use (sese region, bitmap liveouts, basic_block bb,

                       tree use)

{

  unsigned ver;

  basic_block def_bb;

  if (TREE_CODE (use) != SSA_NAME)

    return false;

  ver = SSA_NAME_VERSION (use);

  /* If it's in liveouts, the variable will get a new PHI node, and

     the debug use will be properly adjusted.  */

  if (bitmap_bit_p (liveouts, ver))

    return false;

  def_bb = gimple_bb (SSA_NAME_DEF_STMT (use));

  if (!def_bb

      || !bb_in_sese_p (def_bb, region)

      || bb_in_sese_p (bb, region))

    return false;

  return true;

}

/* Reset debug stmts that reference SSA_NAMES defined in REGION that

   are not marked as liveouts.  */

static void

sese_reset_debug_liveouts_bb (sese region, bitmap liveouts, basic_block bb)

{

  gimple_stmt_iterator bsi;

  ssa_op_iter iter;

  use_operand_p use_p;

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

    {

      gimple stmt = gsi_stmt (bsi);

      if (!is_gimple_debug (stmt))

        continue;

      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)

        if (sese_bad_liveouts_use (region, liveouts, bb,

                                   USE_FROM_PTR (use_p)))

          {

            gimple_debug_bind_reset_value (stmt);

            update_stmt (stmt);

            break;

          }

    }

}

/* Build the LIVEOUTS of REGION: the set of variables defined inside

   and used outside the REGION.  */

static void

sese_build_liveouts (sese region, bitmap liveouts)

{

  basic_block bb;

  FOR_EACH_BB (bb)

    sese_build_liveouts_bb (region, liveouts, bb);

  if (MAY_HAVE_DEBUG_INSNS)

    FOR_EACH_BB (bb)

      sese_reset_debug_liveouts_bb (region, liveouts, bb);

}

/* Builds a new SESE region from edges ENTRY and EXIT.  */

sese

new_sese (edge entry, edge exit)

{

  sese region = XNEW (struct sese_s);

  SESE_ENTRY (region) = entry;

  SESE_EXIT (region) = exit;

  SESE_LOOPS (region) = BITMAP_ALLOC (NULL);

  SESE_LOOP_NEST (region) = VEC_alloc (loop_p, heap, 3);

  SESE_ADD_PARAMS (region) = true;

  SESE_PARAMS (region) = VEC_alloc (tree, heap, 3);

  return region;

}

/* Deletes REGION.  */

void

free_sese (sese region)

{

  if (SESE_LOOPS (region))

    SESE_LOOPS (region) = BITMAP_ALLOC (NULL);

  VEC_free (tree, heap, SESE_PARAMS (region));

  VEC_free (loop_p, heap, SESE_LOOP_NEST (region));

  XDELETE (region);

}

/* Add exit phis for USE on EXIT.  */

static void

sese_add_exit_phis_edge (basic_block exit, tree use, edge false_e, edge true_e)

{

  gimple phi = create_phi_node (use, exit);

  create_new_def_for (gimple_phi_result (phi), phi,

                      gimple_phi_result_ptr (phi));

  add_phi_arg (phi, use, false_e, UNKNOWN_LOCATION);

  add_phi_arg (phi, use, true_e, UNKNOWN_LOCATION);

}

/* Insert in the block BB phi nodes for variables defined in REGION

   and used outside the REGION.  The code generation moves REGION in

   the else clause of an "if (1)" and generates code in the then

   clause that is at this point empty:

   | if (1)

   |   empty;

   | else

   |   REGION;

*/

void

sese_insert_phis_for_liveouts (sese region, basic_block bb,

                               edge false_e, edge true_e)

{

  unsigned i;

  bitmap_iterator bi;

  bitmap liveouts = BITMAP_ALLOC (NULL);

  update_ssa (TODO_update_ssa);

  sese_build_liveouts (region, liveouts);

  EXECUTE_IF_SET_IN_BITMAP (liveouts, 0, i, bi)

    sese_add_exit_phis_edge (bb, ssa_name (i), false_e, true_e);

  BITMAP_FREE (liveouts);

  update_ssa (TODO_update_ssa);

}

/* Returns the first successor edge of BB with EDGE_TRUE_VALUE flag set.  */

edge

get_true_edge_from_guard_bb (basic_block bb)

{

  edge e;

  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, bb->succs)

    if (e->flags & EDGE_TRUE_VALUE)

      return e;

  gcc_unreachable ();

  return NULL;

}

/* Returns the first successor edge of BB with EDGE_TRUE_VALUE flag cleared.  */

edge

get_false_edge_from_guard_bb (basic_block bb)

{

  edge e;

  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, bb->succs)

    if (!(e->flags & EDGE_TRUE_VALUE))

      return e;

  gcc_unreachable ();

  return NULL;

}

/* Returns the expression associated to OLD_NAME in RENAME_MAP.  */

static tree

get_rename (htab_t rename_map, tree old_name)

{

  struct rename_map_elt_s tmp;

  PTR *slot;

  gcc_assert (TREE_CODE (old_name) == SSA_NAME);

  tmp.old_name = old_name;

  slot = htab_find_slot (rename_map, &tmp, NO_INSERT);

  if (slot && *slot)

    return ((rename_map_elt) *slot)->expr;

  return NULL_TREE;

}

/* Register in RENAME_MAP the rename tuple (OLD_NAME, EXPR).  */

static void

set_rename (htab_t rename_map, tree old_name, tree expr)

{

  struct rename_map_elt_s tmp;

  PTR *slot;

  if (old_name == expr)

    return;

  tmp.old_name = old_name;

  slot = htab_find_slot (rename_map, &tmp, INSERT);

  if (!slot)

    return;

  free (*slot);

  *slot = new_rename_map_elt (old_name, expr);

}

/* Renames the scalar uses of the statement COPY, using the

   substitution map RENAME_MAP, inserting the gimplification code at

   GSI_TGT, for the translation REGION, with the original copied

   statement in LOOP, and using the induction variable renaming map

   IV_MAP.  Returns true when something has been renamed.  GLOOG_ERROR

   is set when the code generation cannot continue.  */

static bool

rename_uses (gimple copy, htab_t rename_map, gimple_stmt_iterator *gsi_tgt,

             sese region, loop_p loop, VEC (tree, heap) *iv_map,

             bool *gloog_error)

{

  use_operand_p use_p;

  ssa_op_iter op_iter;

  bool changed = false;

  if (is_gimple_debug (copy))

    {

      if (gimple_debug_bind_p (copy))

        gimple_debug_bind_reset_value (copy);

      else if (gimple_debug_source_bind_p (copy))

        return false;

      else

        gcc_unreachable ();

      return false;

    }

  FOR_EACH_SSA_USE_OPERAND (use_p, copy, op_iter, SSA_OP_ALL_USES)

    {

      tree old_name = USE_FROM_PTR (use_p);

      tree new_expr, scev;

      gimple_seq stmts;

      if (TREE_CODE (old_name) != SSA_NAME

          || !is_gimple_reg (old_name)

          || SSA_NAME_IS_DEFAULT_DEF (old_name))

        continue;

      changed = true;

      new_expr = get_rename (rename_map, old_name);

      if (new_expr)

        {

          tree type_old_name = TREE_TYPE (old_name);

          tree type_new_expr = TREE_TYPE (new_expr);

          if (type_old_name != type_new_expr

              || (TREE_CODE (new_expr) != SSA_NAME

                  && is_gimple_reg (old_name)))

            {

              tree var = create_tmp_var (type_old_name, "var");

              if (type_old_name != type_new_expr)

                new_expr = fold_convert (type_old_name, new_expr);

              new_expr = build2 (MODIFY_EXPR, type_old_name, var, new_expr);

              new_expr = force_gimple_operand (new_expr, &stmts, true, NULL);

              gsi_insert_seq_before (gsi_tgt, stmts, GSI_SAME_STMT);

            }

          replace_exp (use_p, new_expr);

          continue;

        }

      scev = scalar_evolution_in_region (region, loop, old_name);

      /* At this point we should know the exact scev for each

         scalar SSA_NAME used in the scop: all the other scalar

         SSA_NAMEs should have been translated out of SSA using

         arrays with one element.  */

      if (chrec_contains_undetermined (scev))

        {

          *gloog_error = true;

          new_expr = build_zero_cst (TREE_TYPE (old_name));

        }

      else

        new_expr = chrec_apply_map (scev, iv_map);

      /* The apply should produce an expression tree containing

         the uses of the new induction variables.  We should be

         able to use new_expr instead of the old_name in the newly

         generated loop nest.  */

      if (chrec_contains_undetermined (new_expr)

          || tree_contains_chrecs (new_expr, NULL))

        {

          *gloog_error = true;

          new_expr = build_zero_cst (TREE_TYPE (old_name));

        }

      else

        /* Replace the old_name with the new_expr.  */

        new_expr = force_gimple_operand (unshare_expr (new_expr), &stmts,

                                         true, NULL_TREE);

      gsi_insert_seq_before (gsi_tgt, stmts, GSI_SAME_STMT);

      replace_exp (use_p, new_expr);

      if (TREE_CODE (new_expr) == INTEGER_CST

          && is_gimple_assign (copy))

        {

          tree rhs = gimple_assign_rhs1 (copy);

          if (TREE_CODE (rhs) == ADDR_EXPR)

            recompute_tree_invariant_for_addr_expr (rhs);

        }

      set_rename (rename_map, old_name, new_expr);

    }

  return changed;

}

/* Duplicates the statements of basic block BB into basic block NEW_BB

   and compute the new induction variables according to the IV_MAP.

   GLOOG_ERROR is set when the code generation cannot continue.  */

static void

graphite_copy_stmts_from_block (basic_block bb, basic_block new_bb,

                                htab_t rename_map,

                                VEC (tree, heap) *iv_map, sese region,

                                bool *gloog_error)

{

  gimple_stmt_iterator gsi, gsi_tgt;

  loop_p loop = bb->loop_father;

  gsi_tgt = gsi_start_bb (new_bb);

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

    {

      def_operand_p def_p;

      ssa_op_iter op_iter;

      gimple stmt = gsi_stmt (gsi);

      gimple copy;

      tree lhs;

      /* Do not copy labels or conditions.  */

      if (gimple_code (stmt) == GIMPLE_LABEL

          || gimple_code (stmt) == GIMPLE_COND)

        continue;

      /* Do not copy induction variables.  */

      if (is_gimple_assign (stmt)

          && (lhs = gimple_assign_lhs (stmt))

          && TREE_CODE (lhs) == SSA_NAME

          && is_gimple_reg (lhs)

          && scev_analyzable_p (lhs, region))

        continue;

      /* Create a new copy of STMT and duplicate STMT's virtual

         operands.  */

      copy = gimple_copy (stmt);

      gsi_insert_after (&gsi_tgt, copy, GSI_NEW_STMT);

      mark_sym_for_renaming (gimple_vop (cfun));

      maybe_duplicate_eh_stmt (copy, stmt);

      gimple_duplicate_stmt_histograms (cfun, copy, cfun, stmt);

      /* Create new names for all the definitions created by COPY and

         add replacement mappings for each new name.  */

      FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)

        {

          tree old_name = DEF_FROM_PTR (def_p);

          tree new_name = create_new_def_for (old_name, copy, def_p);

          set_rename (rename_map, old_name, new_name);

        }

      if (rename_uses (copy, rename_map, &gsi_tgt, region, loop, iv_map,

                       gloog_error))

        {

          gcc_assert (gsi_stmt (gsi_tgt) == copy);

          fold_stmt_inplace (&gsi_tgt);

        }

      update_stmt (copy);

    }

}

/* Copies BB and includes in the copied BB all the statements that can

   be reached following the use-def chains from the memory accesses,

   and returns the next edge following this new block.  GLOOG_ERROR is

   set when the code generation cannot continue.  */

edge

copy_bb_and_scalar_dependences (basic_block bb, sese region,

                                edge next_e, VEC (tree, heap) *iv_map,

                                bool *gloog_error)

{

  basic_block new_bb = split_edge (next_e);

  htab_t rename_map = htab_create (10, rename_map_elt_info,

                                   eq_rename_map_elts, free);

  next_e = single_succ_edge (new_bb);

  graphite_copy_stmts_from_block (bb, new_bb, rename_map, iv_map, region,

                                  gloog_error);

  remove_phi_nodes (new_bb);

  htab_delete (rename_map);

  return next_e;

}

/* Returns the outermost loop in SCOP that contains BB.  */

struct loop *

outermost_loop_in_sese (sese region, basic_block bb)

{

  struct loop *nest;

  nest = bb->loop_father;

  while (loop_outer (nest)

         && loop_in_sese_p (loop_outer (nest), region))

    nest = loop_outer (nest);

  return nest;

}

/* Sets the false region of an IF_REGION to REGION.  */

void

if_region_set_false_region (ifsese if_region, sese region)

{

  basic_block condition = if_region_get_condition_block (if_region);

  edge false_edge = get_false_edge_from_guard_bb (condition);

  basic_block dummy = false_edge->dest;

  edge entry_region = SESE_ENTRY (region);

  edge exit_region = SESE_EXIT (region);

  basic_block before_region = entry_region->src;

  basic_block last_in_region = exit_region->src;

  void **slot = htab_find_slot_with_hash (current_loops->exits, exit_region,

                                          htab_hash_pointer (exit_region),

                                          NO_INSERT);

  entry_region->flags = false_edge->flags;

  false_edge->flags = exit_region->flags;

  redirect_edge_pred (entry_region, condition);

  redirect_edge_pred (exit_region, before_region);

  redirect_edge_pred (false_edge, last_in_region);

  redirect_edge_succ (false_edge, single_succ (dummy));

  delete_basic_block (dummy);

  exit_region->flags = EDGE_FALLTHRU;

  recompute_all_dominators ();

  SESE_EXIT (region) = false_edge;

  free (if_region->false_region);

  if_region->false_region = region;

  if (slot)

    {

      struct loop_exit *loop_exit = ggc_alloc_cleared_loop_exit ();

      memcpy (loop_exit, *((struct loop_exit **) slot), sizeof (struct loop_exit));