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/* Hooks for cfg representation specific functions.

   Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.

   Contributed by Sebastian Pop <s.pop@laposte.net>

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 "tree.h"

#include "rtl.h"

#include "basic-block.h"

#include "tree-flow.h"

#include "timevar.h"

#include "toplev.h"

/* A pointer to one of the hooks containers.  */

static struct cfg_hooks *cfg_hooks;

/* Initialization of functions specific to the rtl IR.  */

void

rtl_register_cfg_hooks (void)

{

  cfg_hooks = &rtl_cfg_hooks;

}

/* Initialization of functions specific to the rtl IR.  */

void

cfg_layout_rtl_register_cfg_hooks (void)

{

  cfg_hooks = &cfg_layout_rtl_cfg_hooks;

}

/* Initialization of functions specific to the tree IR.  */

void

tree_register_cfg_hooks (void)

{

  cfg_hooks = &tree_cfg_hooks;

}

/* Returns current ir type (rtl = 0, trees = 1).  */

int

ir_type (void)

{

  return cfg_hooks == &tree_cfg_hooks ? 1 : 0;

}

/* Verify the CFG consistency.

   Currently it does following: checks edge and basic block list correctness

   and calls into IL dependent checking then.  */

void

verify_flow_info (void)

{

  size_t *edge_checksum;

  int err = 0;

  basic_block bb, last_bb_seen;

  basic_block *last_visited;

  timevar_push (TV_CFG_VERIFY);

  last_visited = xcalloc (last_basic_block + 2, sizeof (basic_block));

  edge_checksum = xcalloc (last_basic_block + 2, sizeof (size_t));

  /* Check bb chain & numbers.  */

  last_bb_seen = ENTRY_BLOCK_PTR;

  FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb, NULL, next_bb)

    {

      if (bb != EXIT_BLOCK_PTR

          && bb != BASIC_BLOCK (bb->index))

        {

          error ("bb %d on wrong place", bb->index);

          err = 1;

        }

      if (bb->prev_bb != last_bb_seen)

        {

          error ("prev_bb of %d should be %d, not %d",

                 bb->index, last_bb_seen->index, bb->prev_bb->index);

          err = 1;

        }

      last_bb_seen = bb;

    }

  /* Now check the basic blocks (boundaries etc.) */

  FOR_EACH_BB_REVERSE (bb)

    {

      int n_fallthru = 0;

      edge e;

      edge_iterator ei;

      if (bb->count < 0)

        {

          error ("verify_flow_info: Wrong count of block %i %i",

                 bb->index, (int)bb->count);

          err = 1;

        }

      if (bb->frequency < 0)

        {

          error ("verify_flow_info: Wrong frequency of block %i %i",

                 bb->index, bb->frequency);

          err = 1;

        }

      FOR_EACH_EDGE (e, ei, bb->succs)

        {

          if (last_visited [e->dest->index + 2] == bb)

            {

              error ("verify_flow_info: Duplicate edge %i->%i",

                     e->src->index, e->dest->index);

              err = 1;

            }

          if (e->probability < 0 || e->probability > REG_BR_PROB_BASE)

            {

              error ("verify_flow_info: Wrong probability of edge %i->%i %i",

                     e->src->index, e->dest->index, e->probability);

              err = 1;

            }

          if (e->count < 0)

            {

              error ("verify_flow_info: Wrong count of edge %i->%i %i",

                     e->src->index, e->dest->index, (int)e->count);

              err = 1;

            }

          last_visited [e->dest->index + 2] = bb;

          if (e->flags & EDGE_FALLTHRU)

            n_fallthru++;

          if (e->src != bb)

            {

              error ("verify_flow_info: Basic block %d succ edge is corrupted",

                     bb->index);

              fprintf (stderr, "Predecessor: ");

              dump_edge_info (stderr, e, 0);

              fprintf (stderr, "\nSuccessor: ");

              dump_edge_info (stderr, e, 1);

              fprintf (stderr, "\n");

              err = 1;

            }

          edge_checksum[e->dest->index + 2] += (size_t) e;

        }

      if (n_fallthru > 1)

        {

          error ("wrong amount of branch edges after unconditional jump %i", bb->index);

          err = 1;

        }

      FOR_EACH_EDGE (e, ei, bb->preds)

        {

          if (e->dest != bb)

            {

              error ("basic block %d pred edge is corrupted", bb->index);

              fputs ("Predecessor: ", stderr);

              dump_edge_info (stderr, e, 0);

              fputs ("\nSuccessor: ", stderr);

              dump_edge_info (stderr, e, 1);

              fputc ('\n', stderr);

              err = 1;

            }

          if (ei.index != e->dest_idx)

            {

              error ("basic block %d pred edge is corrupted", bb->index);

              error ("its dest_idx should be %d, not %d",

                     ei.index, e->dest_idx);

              fputs ("Predecessor: ", stderr);

              dump_edge_info (stderr, e, 0);

              fputs ("\nSuccessor: ", stderr);

              dump_edge_info (stderr, e, 1);

              fputc ('\n', stderr);

              err = 1;

            }

          edge_checksum[e->dest->index + 2] -= (size_t) e;

        }

    }

  /* Complete edge checksumming for ENTRY and EXIT.  */

  {

    edge e;

    edge_iterator ei;

    FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)

      edge_checksum[e->dest->index + 2] += (size_t) e;

    FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)

      edge_checksum[e->dest->index + 2] -= (size_t) e;

  }

  FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)

    if (edge_checksum[bb->index + 2])

      {

        error ("basic block %i edge lists are corrupted", bb->index);

        err = 1;

      }

  last_bb_seen = ENTRY_BLOCK_PTR;

  /* Clean up.  */

  free (last_visited);

  free (edge_checksum);

  if (cfg_hooks->verify_flow_info)

    err |= cfg_hooks->verify_flow_info ();

  if (err)

    internal_error ("verify_flow_info failed");

  timevar_pop (TV_CFG_VERIFY);

}

/* Print out one basic block.  This function takes care of the purely

   graph related information.  The cfg hook for the active representation

   should dump representation-specific information.  */

void

dump_bb (basic_block bb, FILE *outf, int indent)

{

  edge e;

  edge_iterator ei;

  char *s_indent;

  s_indent = alloca ((size_t) indent + 1);

  memset (s_indent, ' ', (size_t) indent);

  s_indent[indent] = '\0';

  fprintf (outf, ";;%s basic block %d, loop depth %d, count ",

           s_indent, bb->index, bb->loop_depth);

  fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);

  putc ('\n', outf);

  fprintf (outf, ";;%s prev block ", s_indent);

  if (bb->prev_bb)

    fprintf (outf, "%d, ", bb->prev_bb->index);

  else

    fprintf (outf, "(nil), ");

  fprintf (outf, "next block ");

  if (bb->next_bb)

    fprintf (outf, "%d", bb->next_bb->index);

  else

    fprintf (outf, "(nil)");

  putc ('\n', outf);

  fprintf (outf, ";;%s pred:      ", s_indent);

  FOR_EACH_EDGE (e, ei, bb->preds)

    dump_edge_info (outf, e, 0);

  putc ('\n', outf);

  fprintf (outf, ";;%s succ:      ", s_indent);

  FOR_EACH_EDGE (e, ei, bb->succs)

    dump_edge_info (outf, e, 1);

  putc ('\n', outf);

  if (cfg_hooks->dump_bb)

    cfg_hooks->dump_bb (bb, outf, indent);

}

/* Redirect edge E to the given basic block DEST and update underlying program

   representation.  Returns edge representing redirected branch (that may not

   be equivalent to E in the case of duplicate edges being removed) or NULL

   if edge is not easily redirectable for whatever reason.  */

edge

redirect_edge_and_branch (edge e, basic_block dest)

{

  edge ret;

  if (!cfg_hooks->redirect_edge_and_branch)

    internal_error ("%s does not support redirect_edge_and_branch",

                    cfg_hooks->name);

  ret = cfg_hooks->redirect_edge_and_branch (e, dest);

  return ret;

}

/* Redirect the edge E to basic block DEST even if it requires creating

   of a new basic block; then it returns the newly created basic block.

   Aborts when redirection is impossible.  */

basic_block

redirect_edge_and_branch_force (edge e, basic_block dest)

{

  basic_block ret;

  if (!cfg_hooks->redirect_edge_and_branch_force)

    internal_error ("%s does not support redirect_edge_and_branch_force",

                    cfg_hooks->name);

  ret = cfg_hooks->redirect_edge_and_branch_force (e, dest);

  return ret;

}

/* Splits basic block BB after the specified instruction I (but at least after

   the labels).  If I is NULL, splits just after labels.  The newly created edge

   is returned.  The new basic block is created just after the old one.  */

edge

split_block (basic_block bb, void *i)

{

  basic_block new_bb;

  if (!cfg_hooks->split_block)

    internal_error ("%s does not support split_block", cfg_hooks->name);

  new_bb = cfg_hooks->split_block (bb, i);

  if (!new_bb)

    return NULL;

  new_bb->count = bb->count;

  new_bb->frequency = bb->frequency;

  new_bb->loop_depth = bb->loop_depth;

  if (dom_info_available_p (CDI_DOMINATORS))

    {

      redirect_immediate_dominators (CDI_DOMINATORS, bb, new_bb);

      set_immediate_dominator (CDI_DOMINATORS, new_bb, bb);

    }

  return make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU);

}

/* Splits block BB just after labels.  The newly created edge is returned.  */

edge

split_block_after_labels (basic_block bb)

{

  return split_block (bb, NULL);

}

/* Moves block BB immediately after block AFTER.  Returns false if the

   movement was impossible.  */

bool

move_block_after (basic_block bb, basic_block after)

{

  bool ret;

  if (!cfg_hooks->move_block_after)

    internal_error ("%s does not support move_block_after", cfg_hooks->name);

  ret = cfg_hooks->move_block_after (bb, after);

  return ret;

}

/* Deletes the basic block BB.  */

void

delete_basic_block (basic_block bb)

{

  if (!cfg_hooks->delete_basic_block)

    internal_error ("%s does not support delete_basic_block", cfg_hooks->name);

  cfg_hooks->delete_basic_block (bb);

  /* Remove the edges into and out of this block.  Note that there may

     indeed be edges in, if we are removing an unreachable loop.  */

  while (EDGE_COUNT (bb->preds) != 0)

    remove_edge (EDGE_PRED (bb, 0));

  while (EDGE_COUNT (bb->succs) != 0)

    remove_edge (EDGE_SUCC (bb, 0));

  if (dom_computed[CDI_DOMINATORS])

    delete_from_dominance_info (CDI_DOMINATORS, bb);

  if (dom_computed[CDI_POST_DOMINATORS])

    delete_from_dominance_info (CDI_POST_DOMINATORS, bb);

  /* Remove the basic block from the array.  */

  expunge_block (bb);

}

/* Splits edge E and returns the newly created basic block.  */

basic_block

split_edge (edge e)

{

  basic_block ret;

  gcov_type count = e->count;

  int freq = EDGE_FREQUENCY (e);

  edge f;

  bool irr = (e->flags & EDGE_IRREDUCIBLE_LOOP) != 0;

  if (!cfg_hooks->split_edge)

    internal_error ("%s does not support split_edge", cfg_hooks->name);

  ret = cfg_hooks->split_edge (e);

  ret->count = count;

  ret->frequency = freq;

  single_succ_edge (ret)->probability = REG_BR_PROB_BASE;

  single_succ_edge (ret)->count = count;

  if (irr)

    {

      ret->flags |= BB_IRREDUCIBLE_LOOP;

      single_pred_edge (ret)->flags |= EDGE_IRREDUCIBLE_LOOP;

      single_succ_edge (ret)->flags |= EDGE_IRREDUCIBLE_LOOP;

    }

  if (dom_computed[CDI_DOMINATORS])

    set_immediate_dominator (CDI_DOMINATORS, ret, single_pred (ret));

  if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)

    {

      /* There are two cases:

         If the immediate dominator of e->dest is not e->src, it

         remains unchanged.

         If immediate dominator of e->dest is e->src, it may become

         ret, provided that all other predecessors of e->dest are

         dominated by e->dest.  */

      if (get_immediate_dominator (CDI_DOMINATORS, single_succ (ret))

          == single_pred (ret))

        {

          edge_iterator ei;

          FOR_EACH_EDGE (f, ei, single_succ (ret)->preds)

            {

              if (f == single_succ_edge (ret))

                continue;

              if (!dominated_by_p (CDI_DOMINATORS, f->src,

                                   single_succ (ret)))

                break;

            }

          if (!f)

            set_immediate_dominator (CDI_DOMINATORS, single_succ (ret), ret);

        }

    };

  return ret;

}

/* Creates a new basic block just after the basic block AFTER.

   HEAD and END are the first and the last statement belonging

   to the block.  If both are NULL, an empty block is created.  */

basic_block

create_basic_block (void *head, void *end, basic_block after)

{

  basic_block ret;

  if (!cfg_hooks->create_basic_block)

    internal_error ("%s does not support create_basic_block", cfg_hooks->name);

  ret = cfg_hooks->create_basic_block (head, end, after);

  if (dom_computed[CDI_DOMINATORS])

    add_to_dominance_info (CDI_DOMINATORS, ret);

  if (dom_computed[CDI_POST_DOMINATORS])

    add_to_dominance_info (CDI_POST_DOMINATORS, ret);

  return ret;

}

/* Creates an empty basic block just after basic block AFTER.  */

basic_block

create_empty_bb (basic_block after)

{

  return create_basic_block (NULL, NULL, after);

}

/* Checks whether we may merge blocks BB1 and BB2.  */

bool

can_merge_blocks_p (basic_block bb1, basic_block bb2)

{

  bool ret;

  if (!cfg_hooks->can_merge_blocks_p)

    internal_error ("%s does not support can_merge_blocks_p", cfg_hooks->name);

  ret = cfg_hooks->can_merge_blocks_p (bb1, bb2);

  return ret;

}

void

predict_edge (edge e, enum br_predictor predictor, int probability)

{

  if (!cfg_hooks->predict_edge)

    internal_error ("%s does not support predict_edge", cfg_hooks->name);

  cfg_hooks->predict_edge (e, predictor, probability);

}

bool

predicted_by_p (basic_block bb, enum br_predictor predictor)

{

  if (!cfg_hooks->predict_edge)

    internal_error ("%s does not support predicted_by_p", cfg_hooks->name);

  return cfg_hooks->predicted_by_p (bb, predictor);

}

/* Merges basic block B into basic block A.  */

void

merge_blocks (basic_block a, basic_block b)

{

  edge e;

  edge_iterator ei;

  if (!cfg_hooks->merge_blocks)

    internal_error ("%s does not support merge_blocks", cfg_hooks->name);

  cfg_hooks->merge_blocks (a, b);

  /* Normally there should only be one successor of A and that is B, but

     partway though the merge of blocks for conditional_execution we'll

     be merging a TEST block with THEN and ELSE successors.  Free the

     whole lot of them and hope the caller knows what they're doing.  */

  while (EDGE_COUNT (a->succs) != 0)

   remove_edge (EDGE_SUCC (a, 0));

  /* Adjust the edges out of B for the new owner.  */

  FOR_EACH_EDGE (e, ei, b->succs)

    e->src = a;

  a->succs = b->succs;

  a->flags |= b->flags;

  /* B hasn't quite yet ceased to exist.  Attempt to prevent mishap.  */

  b->preds = b->succs = NULL;

  if (dom_computed[CDI_DOMINATORS])

    redirect_immediate_dominators (CDI_DOMINATORS, b, a);

  if (dom_computed[CDI_DOMINATORS])

    delete_from_dominance_info (CDI_DOMINATORS, b);

  if (dom_computed[CDI_POST_DOMINATORS])

    delete_from_dominance_info (CDI_POST_DOMINATORS, b);

  expunge_block (b);

}

/* Split BB into entry part and the rest (the rest is the newly created block).

   Redirect those edges for that REDIRECT_EDGE_P returns true to the entry

   part.  Returns the edge connecting the entry part to the rest.  */

edge

make_forwarder_block (basic_block bb, bool (*redirect_edge_p) (edge),

                      void (*new_bb_cbk) (basic_block))

{

  edge e, fallthru;

  edge_iterator ei;

  basic_block dummy, jump;

  if (!cfg_hooks->make_forwarder_block)

    internal_error ("%s does not support make_forwarder_block",

                    cfg_hooks->name);

  fallthru = split_block_after_labels (bb);

  dummy = fallthru->src;

  bb = fallthru->dest;

  /* Redirect back edges we want to keep.  */

  for (ei = ei_start (dummy->preds); (e = ei_safe_edge (ei)); )

    {

      if (redirect_edge_p (e))

        {

          ei_next (&ei);

          continue;

        }

      dummy->frequency -= EDGE_FREQUENCY (e);

      dummy->count -= e->count;

      if (dummy->frequency < 0)

        dummy->frequency = 0;

      if (dummy->count < 0)

        dummy->count = 0;

      fallthru->count -= e->count;

      if (fallthru->count < 0)

        fallthru->count = 0;

      jump = redirect_edge_and_branch_force (e, bb);

      if (jump)

        new_bb_cbk (jump);

    }

  if (dom_info_available_p (CDI_DOMINATORS))

    {

      basic_block doms_to_fix[2];

      doms_to_fix[0] = dummy;

      doms_to_fix[1] = bb;

      iterate_fix_dominators (CDI_DOMINATORS, doms_to_fix, 2);

    }

  cfg_hooks->make_forwarder_block (fallthru);

  return fallthru;

}

void

tidy_fallthru_edge (edge e)

{

  if (cfg_hooks->tidy_fallthru_edge)

    cfg_hooks->tidy_fallthru_edge (e);

}

/* Fix up edges that now fall through, or rather should now fall through

   but previously required a jump around now deleted blocks.  Simplify

   the search by only examining blocks numerically adjacent, since this

   is how find_basic_blocks created them.  */

void

tidy_fallthru_edges (void)

{

  basic_block b, c;

  if (!cfg_hooks->tidy_fallthru_edge)

    return;

  if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)

    return;

  FOR_BB_BETWEEN (b, ENTRY_BLOCK_PTR->next_bb, EXIT_BLOCK_PTR->prev_bb, next_bb)

    {

      edge s;

      c = b->next_bb;

      /* We care about simple conditional or unconditional jumps with

         a single successor.

         If we had a conditional branch to the next instruction when

         find_basic_blocks was called, then there will only be one

         out edge for the block which ended with the conditional

         branch (since we do not create duplicate edges).

         Furthermore, the edge will be marked as a fallthru because we

         merge the flags for the duplicate edges.  So we do not want to

         check that the edge is not a FALLTHRU edge.  */

      if (single_succ_p (b))

        {

          s = single_succ_edge (b);

          if (! (s->flags & EDGE_COMPLEX)

              && s->dest == c

              && !find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX))

            tidy_fallthru_edge (s);

        }

    }

}

/* Returns true if we can duplicate basic block BB.  */

bool

can_duplicate_block_p (basic_block bb)

{

  edge e;

  if (!cfg_hooks->can_duplicate_block_p)

    internal_error ("%s does not support can_duplicate_block_p",

                    cfg_hooks->name);

  if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR)

    return false;

  /* Duplicating fallthru block to exit would require adding a jump

     and splitting the real last BB.  */

  e = find_edge (bb, EXIT_BLOCK_PTR);

  if (e && (e->flags & EDGE_FALLTHRU))

    return false;

  return cfg_hooks->can_duplicate_block_p (bb);

}

/* Duplicates basic block BB and redirects edge E to it.  Returns the

   new basic block.  The new basic block is placed after the basic block

   AFTER.  */

basic_block

duplicate_block (basic_block bb, edge e, basic_block after)

{

  edge s, n;

  basic_block new_bb;