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/* Optimization of PHI nodes by converting them into straightline code.

/* Optimization of PHI nodes by converting them into straightline code.

   Copyright (C) 2004, 2005, 2007 Free Software Foundation, Inc.

   Copyright (C) 2004, 2005, 2007 Free Software Foundation, Inc.

This file is part of GCC.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it

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

under the terms of the GNU General Public License as published by the

Free Software Foundation; either version 3, or (at your option) any

Free Software Foundation; either version 3, or (at your option) any

later version.

later version.

GCC is distributed in the hope that it will be useful, but WITHOUT

GCC is distributed in the hope that it will be useful, but WITHOUT

ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

for more details.

You should have received a copy of the GNU General Public License

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "config.h"

#include "system.h"

#include "system.h"

#include "coretypes.h"

#include "coretypes.h"

#include "tm.h"

#include "tm.h"

#include "ggc.h"

#include "ggc.h"

#include "tree.h"

#include "tree.h"

#include "rtl.h"

#include "rtl.h"

#include "flags.h"

#include "flags.h"

#include "tm_p.h"

#include "tm_p.h"

#include "basic-block.h"

#include "basic-block.h"

#include "timevar.h"

#include "timevar.h"

#include "diagnostic.h"

#include "diagnostic.h"

#include "tree-flow.h"

#include "tree-flow.h"

#include "tree-pass.h"

#include "tree-pass.h"

#include "tree-dump.h"

#include "tree-dump.h"

#include "langhooks.h"

#include "langhooks.h"

static unsigned int tree_ssa_phiopt (void);

static unsigned int tree_ssa_phiopt (void);

static bool conditional_replacement (basic_block, basic_block,

static bool conditional_replacement (basic_block, basic_block,

                                     edge, edge, tree, tree, tree);

                                     edge, edge, tree, tree, tree);

static bool value_replacement (basic_block, basic_block,

static bool value_replacement (basic_block, basic_block,

                               edge, edge, tree, tree, tree);

                               edge, edge, tree, tree, tree);

static bool minmax_replacement (basic_block, basic_block,

static bool minmax_replacement (basic_block, basic_block,

                                edge, edge, tree, tree, tree);

                                edge, edge, tree, tree, tree);

static bool abs_replacement (basic_block, basic_block,

static bool abs_replacement (basic_block, basic_block,

                             edge, edge, tree, tree, tree);

                             edge, edge, tree, tree, tree);

static void replace_phi_edge_with_variable (basic_block, edge, tree, tree);

static void replace_phi_edge_with_variable (basic_block, edge, tree, tree);

static basic_block *blocks_in_phiopt_order (void);

static basic_block *blocks_in_phiopt_order (void);

/* This pass tries to replaces an if-then-else block with an

/* This pass tries to replaces an if-then-else block with an

   assignment.  We have four kinds of transformations.  Some of these

   assignment.  We have four kinds of transformations.  Some of these

   transformations are also performed by the ifcvt RTL optimizer.

   transformations are also performed by the ifcvt RTL optimizer.

   Conditional Replacement

   Conditional Replacement

   -----------------------

   -----------------------

   This transformation, implemented in conditional_replacement,

   This transformation, implemented in conditional_replacement,

   replaces

   replaces

     bb0:

     bb0:

      if (cond) goto bb2; else goto bb1;

      if (cond) goto bb2; else goto bb1;

     bb1:

     bb1:

     bb2:

     bb2:

      x = PHI <0 (bb1), 1 (bb0), ...>;

      x = PHI <0 (bb1), 1 (bb0), ...>;

   with

   with

     bb0:

     bb0:

      x' = cond;

      x' = cond;

      goto bb2;

      goto bb2;

     bb2:

     bb2:

      x = PHI <x' (bb0), ...>;

      x = PHI <x' (bb0), ...>;

   We remove bb1 as it becomes unreachable.  This occurs often due to

   We remove bb1 as it becomes unreachable.  This occurs often due to

   gimplification of conditionals.

   gimplification of conditionals.

   Value Replacement

   Value Replacement

   -----------------

   -----------------

   This transformation, implemented in value_replacement, replaces

   This transformation, implemented in value_replacement, replaces

     bb0:

     bb0:

       if (a != b) goto bb2; else goto bb1;

       if (a != b) goto bb2; else goto bb1;

     bb1:

     bb1:

     bb2:

     bb2:

       x = PHI <a (bb1), b (bb0), ...>;

       x = PHI <a (bb1), b (bb0), ...>;

   with

   with

     bb0:

     bb0:

     bb2:

     bb2:

       x = PHI <b (bb0), ...>;

       x = PHI <b (bb0), ...>;

   This opportunity can sometimes occur as a result of other

   This opportunity can sometimes occur as a result of other

   optimizations.

   optimizations.

   ABS Replacement

   ABS Replacement

   ---------------

   ---------------

   This transformation, implemented in abs_replacement, replaces

   This transformation, implemented in abs_replacement, replaces

     bb0:

     bb0:

       if (a >= 0) goto bb2; else goto bb1;

       if (a >= 0) goto bb2; else goto bb1;

     bb1:

     bb1:

       x = -a;

       x = -a;

     bb2:

     bb2:

       x = PHI <x (bb1), a (bb0), ...>;

       x = PHI <x (bb1), a (bb0), ...>;

   with

   with

     bb0:

     bb0:

       x' = ABS_EXPR< a >;

       x' = ABS_EXPR< a >;

     bb2:

     bb2:

       x = PHI <x' (bb0), ...>;

       x = PHI <x' (bb0), ...>;

   MIN/MAX Replacement

   MIN/MAX Replacement

   -------------------

   -------------------

   This transformation, minmax_replacement replaces

   This transformation, minmax_replacement replaces

     bb0:

     bb0:

       if (a <= b) goto bb2; else goto bb1;

       if (a <= b) goto bb2; else goto bb1;

     bb1:

     bb1:

     bb2:

     bb2:

       x = PHI <b (bb1), a (bb0), ...>;

       x = PHI <b (bb1), a (bb0), ...>;

   with

   with

     bb0:

     bb0:

       x' = MIN_EXPR (a, b)

       x' = MIN_EXPR (a, b)

     bb2:

     bb2:

       x = PHI <x' (bb0), ...>;

       x = PHI <x' (bb0), ...>;

   A similar transformation is done for MAX_EXPR.  */

   A similar transformation is done for MAX_EXPR.  */

static unsigned int

static unsigned int

tree_ssa_phiopt (void)

tree_ssa_phiopt (void)

{

{

  basic_block bb;

  basic_block bb;

  basic_block *bb_order;

  basic_block *bb_order;

  unsigned n, i;

  unsigned n, i;

  bool cfgchanged = false;

  bool cfgchanged = false;

  /* Search every basic block for COND_EXPR we may be able to optimize.

  /* Search every basic block for COND_EXPR we may be able to optimize.

     We walk the blocks in order that guarantees that a block with

     We walk the blocks in order that guarantees that a block with

     a single predecessor is processed before the predecessor.

     a single predecessor is processed before the predecessor.

     This ensures that we collapse inner ifs before visiting the

     This ensures that we collapse inner ifs before visiting the

     outer ones, and also that we do not try to visit a removed

     outer ones, and also that we do not try to visit a removed

     block.  */

     block.  */

  bb_order = blocks_in_phiopt_order ();

  bb_order = blocks_in_phiopt_order ();

  n = n_basic_blocks - NUM_FIXED_BLOCKS;

  n = n_basic_blocks - NUM_FIXED_BLOCKS;

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

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

    {

    {

      tree cond_expr;

      tree cond_expr;

      tree phi;

      tree phi;

      basic_block bb1, bb2;

      basic_block bb1, bb2;

      edge e1, e2;

      edge e1, e2;

      tree arg0, arg1;

      tree arg0, arg1;

      bb = bb_order[i];

      bb = bb_order[i];

      cond_expr = last_stmt (bb);

      cond_expr = last_stmt (bb);

      /* Check to see if the last statement is a COND_EXPR.  */

      /* Check to see if the last statement is a COND_EXPR.  */

      if (!cond_expr

      if (!cond_expr

          || TREE_CODE (cond_expr) != COND_EXPR)

          || TREE_CODE (cond_expr) != COND_EXPR)

        continue;

        continue;

      e1 = EDGE_SUCC (bb, 0);

      e1 = EDGE_SUCC (bb, 0);

      bb1 = e1->dest;

      bb1 = e1->dest;

      e2 = EDGE_SUCC (bb, 1);

      e2 = EDGE_SUCC (bb, 1);

      bb2 = e2->dest;

      bb2 = e2->dest;

      /* We cannot do the optimization on abnormal edges.  */

      /* We cannot do the optimization on abnormal edges.  */

      if ((e1->flags & EDGE_ABNORMAL) != 0

      if ((e1->flags & EDGE_ABNORMAL) != 0

          || (e2->flags & EDGE_ABNORMAL) != 0)

          || (e2->flags & EDGE_ABNORMAL) != 0)

       continue;

       continue;

      /* If either bb1's succ or bb2 or bb2's succ is non NULL.  */

      /* If either bb1's succ or bb2 or bb2's succ is non NULL.  */

      if (EDGE_COUNT (bb1->succs) == 0

      if (EDGE_COUNT (bb1->succs) == 0

          || bb2 == NULL

          || bb2 == NULL

          || EDGE_COUNT (bb2->succs) == 0)

          || EDGE_COUNT (bb2->succs) == 0)

        continue;

        continue;

      /* Find the bb which is the fall through to the other.  */

      /* Find the bb which is the fall through to the other.  */

      if (EDGE_SUCC (bb1, 0)->dest == bb2)

      if (EDGE_SUCC (bb1, 0)->dest == bb2)

        ;

        ;

      else if (EDGE_SUCC (bb2, 0)->dest == bb1)

      else if (EDGE_SUCC (bb2, 0)->dest == bb1)

        {

        {

          basic_block bb_tmp = bb1;

          basic_block bb_tmp = bb1;

          edge e_tmp = e1;

          edge e_tmp = e1;

          bb1 = bb2;

          bb1 = bb2;

          bb2 = bb_tmp;

          bb2 = bb_tmp;

          e1 = e2;

          e1 = e2;

          e2 = e_tmp;

          e2 = e_tmp;

        }

        }

      else

      else

        continue;

        continue;

      e1 = EDGE_SUCC (bb1, 0);

      e1 = EDGE_SUCC (bb1, 0);

      /* Make sure that bb1 is just a fall through.  */

      /* Make sure that bb1 is just a fall through.  */

      if (!single_succ_p (bb1)

      if (!single_succ_p (bb1)

          || (e1->flags & EDGE_FALLTHRU) == 0)

          || (e1->flags & EDGE_FALLTHRU) == 0)

        continue;

        continue;

      /* Also make sure that bb1 only have one predecessor and that it

      /* Also make sure that bb1 only have one predecessor and that it

         is bb.  */

         is bb.  */

      if (!single_pred_p (bb1)

      if (!single_pred_p (bb1)

          || single_pred (bb1) != bb)

          || single_pred (bb1) != bb)

        continue;

        continue;

      phi = phi_nodes (bb2);

      phi = phi_nodes (bb2);

      /* Check to make sure that there is only one PHI node.

      /* Check to make sure that there is only one PHI node.

         TODO: we could do it with more than one iff the other PHI nodes

         TODO: we could do it with more than one iff the other PHI nodes

         have the same elements for these two edges.  */

         have the same elements for these two edges.  */

      if (!phi || PHI_CHAIN (phi) != NULL)

      if (!phi || PHI_CHAIN (phi) != NULL)

        continue;

        continue;

      arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx);

      arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx);

      arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx);

      arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx);

      /* Something is wrong if we cannot find the arguments in the PHI

      /* Something is wrong if we cannot find the arguments in the PHI

         node.  */

         node.  */

      gcc_assert (arg0 != NULL && arg1 != NULL);

      gcc_assert (arg0 != NULL && arg1 != NULL);

      /* Do the replacement of conditional if it can be done.  */

      /* Do the replacement of conditional if it can be done.  */

      if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

      if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

        cfgchanged = true;

        cfgchanged = true;

      else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

      else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

        cfgchanged = true;

        cfgchanged = true;

      else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

      else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

        cfgchanged = true;

        cfgchanged = true;

      else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

      else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))

        cfgchanged = true;

        cfgchanged = true;

    }

    }

  free (bb_order);

  free (bb_order);

  /* If the CFG has changed, we should cleanup the CFG. */

  /* If the CFG has changed, we should cleanup the CFG. */

  return cfgchanged ? TODO_cleanup_cfg : 0;

  return cfgchanged ? TODO_cleanup_cfg : 0;

}

}

/* Returns the list of basic blocks in the function in an order that guarantees

/* Returns the list of basic blocks in the function in an order that guarantees

   that if a block X has just a single predecessor Y, then Y is after X in the

   that if a block X has just a single predecessor Y, then Y is after X in the

   ordering.  */

   ordering.  */

static basic_block *

static basic_block *

blocks_in_phiopt_order (void)

blocks_in_phiopt_order (void)

{

{

  basic_block x, y;

  basic_block x, y;

  basic_block *order = XNEWVEC (basic_block, n_basic_blocks);

  basic_block *order = XNEWVEC (basic_block, n_basic_blocks);

  unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS;

  unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS;

  unsigned np, i;

  unsigned np, i;

  sbitmap visited = sbitmap_alloc (last_basic_block);

  sbitmap visited = sbitmap_alloc (last_basic_block);

#define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index)) 

#define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index)) 

#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index)) 

#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index)) 

  sbitmap_zero (visited);

  sbitmap_zero (visited);

  MARK_VISITED (ENTRY_BLOCK_PTR);

  MARK_VISITED (ENTRY_BLOCK_PTR);

  FOR_EACH_BB (x)

  FOR_EACH_BB (x)

    {

    {

      if (VISITED_P (x))

      if (VISITED_P (x))

        continue;

        continue;

      /* Walk the predecessors of x as long as they have precisely one

      /* Walk the predecessors of x as long as they have precisely one

         predecessor and add them to the list, so that they get stored

         predecessor and add them to the list, so that they get stored

         after x.  */

         after x.  */

      for (y = x, np = 1;

      for (y = x, np = 1;

           single_pred_p (y) && !VISITED_P (single_pred (y));

           single_pred_p (y) && !VISITED_P (single_pred (y));

           y = single_pred (y))

           y = single_pred (y))

        np++;

        np++;

      for (y = x, i = n - np;

      for (y = x, i = n - np;

           single_pred_p (y) && !VISITED_P (single_pred (y));

           single_pred_p (y) && !VISITED_P (single_pred (y));

           y = single_pred (y), i++)

           y = single_pred (y), i++)

        {

        {

          order[i] = y;

          order[i] = y;

          MARK_VISITED (y);

          MARK_VISITED (y);

        }

        }

      order[i] = y;

      order[i] = y;

      MARK_VISITED (y);

      MARK_VISITED (y);

      gcc_assert (i == n - 1);

      gcc_assert (i == n - 1);

      n -= np;

      n -= np;

    }

    }

  sbitmap_free (visited);

  sbitmap_free (visited);

  gcc_assert (n == 0);

  gcc_assert (n == 0);

  return order;

  return order;

#undef MARK_VISITED

#undef MARK_VISITED

#undef VISITED_P

#undef VISITED_P

}

}

/* Return TRUE if block BB has no executable statements, otherwise return

/* Return TRUE if block BB has no executable statements, otherwise return

   FALSE.  */

   FALSE.  */

bool

bool

empty_block_p (basic_block bb)

empty_block_p (basic_block bb)

{

{

  block_stmt_iterator bsi;

  block_stmt_iterator bsi;

  /* BB must have no executable statements.  */

  /* BB must have no executable statements.  */

  bsi = bsi_start (bb);

  bsi = bsi_start (bb);

  while (!bsi_end_p (bsi)

  while (!bsi_end_p (bsi)

          && (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR

          && (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR

              || IS_EMPTY_STMT (bsi_stmt (bsi))))

              || IS_EMPTY_STMT (bsi_stmt (bsi))))

    bsi_next (&bsi);

    bsi_next (&bsi);

  if (!bsi_end_p (bsi))

  if (!bsi_end_p (bsi))

    return false;

    return false;

  return true;

  return true;

}

}

/* Replace PHI node element whose edge is E in block BB with variable NEW.

/* Replace PHI node element whose edge is E in block BB with variable NEW.

   Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK

   Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK

   is known to have two edges, one of which must reach BB).  */

   is known to have two edges, one of which must reach BB).  */

static void

static void

replace_phi_edge_with_variable (basic_block cond_block,

replace_phi_edge_with_variable (basic_block cond_block,

                                edge e, tree phi, tree new)

                                edge e, tree phi, tree new)

{

{

  basic_block bb = bb_for_stmt (phi);

  basic_block bb = bb_for_stmt (phi);

  basic_block block_to_remove;

  basic_block block_to_remove;

  block_stmt_iterator bsi;

  block_stmt_iterator bsi;

  /* Change the PHI argument to new.  */

  /* Change the PHI argument to new.  */

  SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new);

  SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new);

  /* Remove the empty basic block.  */

  /* Remove the empty basic block.  */

  if (EDGE_SUCC (cond_block, 0)->dest == bb)

  if (EDGE_SUCC (cond_block, 0)->dest == bb)

    {

    {

      EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU;

      EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU;

      EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);

      EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);

      EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE;

      EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE;

      EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count;

      EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count;

      block_to_remove = EDGE_SUCC (cond_block, 1)->dest;

      block_to_remove = EDGE_SUCC (cond_block, 1)->dest;

    }

    }

  else

  else

    {

    {

      EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;

      EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;

      EDGE_SUCC (cond_block, 1)->flags

      EDGE_SUCC (cond_block, 1)->flags

        &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);

        &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);

      EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE;

      EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE;

      EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count;

      EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count;

      block_to_remove = EDGE_SUCC (cond_block, 0)->dest;

      block_to_remove = EDGE_SUCC (cond_block, 0)->dest;

    }

    }

  delete_basic_block (block_to_remove);

  delete_basic_block (block_to_remove);

  /* Eliminate the COND_EXPR at the end of COND_BLOCK.  */

  /* Eliminate the COND_EXPR at the end of COND_BLOCK.  */

  bsi = bsi_last (cond_block);

  bsi = bsi_last (cond_block);

  bsi_remove (&bsi, true);

  bsi_remove (&bsi, true);

  if (dump_file && (dump_flags & TDF_DETAILS))

  if (dump_file && (dump_flags & TDF_DETAILS))

    fprintf (dump_file,

    fprintf (dump_file,

              "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",

              "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",

              cond_block->index,

              cond_block->index,

              bb->index);

              bb->index);

}

}

/*  The function conditional_replacement does the main work of doing the

/*  The function conditional_replacement does the main work of doing the

    conditional replacement.  Return true if the replacement is done.

    conditional replacement.  Return true if the replacement is done.

    Otherwise return false.

    Otherwise return false.

    BB is the basic block where the replacement is going to be done on.  ARG0

    BB is the basic block where the replacement is going to be done on.  ARG0

    is argument 0 from PHI.  Likewise for ARG1.  */

    is argument 0 from PHI.  Likewise for ARG1.  */

static bool

static bool

conditional_replacement (basic_block cond_bb, basic_block middle_bb,

conditional_replacement (basic_block cond_bb, basic_block middle_bb,

                         edge e0, edge e1, tree phi,

                         edge e0, edge e1, tree phi,

                         tree arg0, tree arg1)

                         tree arg0, tree arg1)

{

{

  tree result;

  tree result;

  tree old_result = NULL;

  tree old_result = NULL;

  tree new, cond;

  tree new, cond;

  block_stmt_iterator bsi;

  block_stmt_iterator bsi;

  edge true_edge, false_edge;

  edge true_edge, false_edge;

  tree new_var = NULL;

  tree new_var = NULL;

  tree new_var1;

  tree new_var1;

  /* The PHI arguments have the constants 0 and 1, then convert

  /* The PHI arguments have the constants 0 and 1, then convert

     it to the conditional.  */

     it to the conditional.  */

  if ((integer_zerop (arg0) && integer_onep (arg1))

  if ((integer_zerop (arg0) && integer_onep (arg1))

      || (integer_zerop (arg1) && integer_onep (arg0)))

      || (integer_zerop (arg1) && integer_onep (arg0)))

    ;

    ;

  else

  else

    return false;

    return false;

  if (!empty_block_p (middle_bb))

  if (!empty_block_p (middle_bb))

    return false;

    return false;

  /* If the condition is not a naked SSA_NAME and its type does not

  /* If the condition is not a naked SSA_NAME and its type does not

     match the type of the result, then we have to create a new

     match the type of the result, then we have to create a new

     variable to optimize this case as it would likely create

     variable to optimize this case as it would likely create

     non-gimple code when the condition was converted to the

     non-gimple code when the condition was converted to the

     result's type.  */

     result's type.  */

  cond = COND_EXPR_COND (last_stmt (cond_bb));

  cond = COND_EXPR_COND (last_stmt (cond_bb));

  result = PHI_RESULT (phi);

  result = PHI_RESULT (phi);

  if (TREE_CODE (cond) != SSA_NAME

  if (TREE_CODE (cond) != SSA_NAME

      && !lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result)))

      && !lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result)))

    {

    {

      tree tmp;

      tree tmp;

      if (!COMPARISON_CLASS_P (cond))

      if (!COMPARISON_CLASS_P (cond))

        return false;

        return false;

      tmp = create_tmp_var (TREE_TYPE (cond), NULL);

      tmp = create_tmp_var (TREE_TYPE (cond), NULL);

      add_referenced_var (tmp);

      add_referenced_var (tmp);

      new_var = make_ssa_name (tmp, NULL);

      new_var = make_ssa_name (tmp, NULL);

      old_result = cond;

      old_result = cond;

      cond = new_var;

      cond = new_var;

    }

    }

  /* If the condition was a naked SSA_NAME and the type is not the

  /* If the condition was a naked SSA_NAME and the type is not the

     same as the type of the result, then convert the type of the

     same as the type of the result, then convert the type of the

     condition.  */

     condition.  */

  if (!lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result)))

  if (!lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result)))

    cond = fold_convert (TREE_TYPE (result), cond);

    cond = fold_convert (TREE_TYPE (result), cond);

  /* We need to know which is the true edge and which is the false

  /* We need to know which is the true edge and which is the false

     edge so that we know when to invert the condition below.  */

     edge so that we know when to invert the condition below.  */

  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);

  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);

  /* Insert our new statement at the end of conditional block before the

  /* Insert our new statement at the end of conditional block before the

     COND_EXPR.  */

     COND_EXPR.  */

  bsi = bsi_last (cond_bb);

  bsi = bsi_last (cond_bb);

  bsi_insert_before (&bsi, build_empty_stmt (), BSI_NEW_STMT);

  bsi_insert_before (&bsi, build_empty_stmt (), BSI_NEW_STMT);

  if (old_result)

  if (old_result)

    {

    {

      tree new1;

      tree new1;

      new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result),

      new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result),

                     TREE_OPERAND (old_result, 0),

                     TREE_OPERAND (old_result, 0),

                     TREE_OPERAND (old_result, 1));

                     TREE_OPERAND (old_result, 1));

      new1 = build2 (MODIFY_EXPR, TREE_TYPE (old_result), new_var, new1);

      new1 = build2 (MODIFY_EXPR, TREE_TYPE (old_result), new_var, new1);

      SSA_NAME_DEF_STMT (new_var) = new1;

      SSA_NAME_DEF_STMT (new_var) = new1;

      bsi_insert_after (&bsi, new1, BSI_NEW_STMT);

      bsi_insert_after (&bsi, new1, BSI_NEW_STMT);

    }

    }

  new_var1 = duplicate_ssa_name (PHI_RESULT (phi), NULL);

  new_var1 = duplicate_ssa_name (PHI_RESULT (phi), NULL);

  /* At this point we know we have a COND_EXPR with two successors.

  /* At this point we know we have a COND_EXPR with two successors.

     One successor is BB, the other successor is an empty block which

     One successor is BB, the other successor is an empty block which

     falls through into BB.

     falls through into BB.

     There is a single PHI node at the join point (BB) and its arguments

     There is a single PHI node at the join point (BB) and its arguments

     are constants (0, 1).

     are constants (0, 1).

     So, given the condition COND, and the two PHI arguments, we can

     So, given the condition COND, and the two PHI arguments, we can

     rewrite this PHI into non-branching code:

     rewrite this PHI into non-branching code:

       dest = (COND) or dest = COND'

       dest = (COND) or dest = COND'

     We use the condition as-is if the argument associated with the

     We use the condition as-is if the argument associated with the

     true edge has the value one or the argument associated with the

     true edge has the value one or the argument associated with the

     false edge as the value zero.  Note that those conditions are not

     false edge as the value zero.  Note that those conditions are not

     the same since only one of the outgoing edges from the COND_EXPR

     the same since only one of the outgoing edges from the COND_EXPR

     will directly reach BB and thus be associated with an argument.  */

     will directly reach BB and thus be associated with an argument.  */

  if ((e0 == true_edge && integer_onep (arg0))

  if ((e0 == true_edge && integer_onep (arg0))

      || (e0 == false_edge && integer_zerop (arg0))

      || (e0 == false_edge && integer_zerop (arg0))

      || (e1 == true_edge && integer_onep (arg1))

      || (e1 == true_edge && integer_onep (arg1))

      || (e1 == false_edge && integer_zerop (arg1)))

      || (e1 == false_edge && integer_zerop (arg1)))

    {

    {

      new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond);

      new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond);

    }

    }

  else

  else

    {

    {

      tree cond1 = invert_truthvalue (cond);

      tree cond1 = invert_truthvalue (cond);

      cond = cond1;

      cond = cond1;

      /* If what we get back is a conditional expression, there is no

      /* If what we get back is a conditional expression, there is no

          way that it can be gimple.  */

          way that it can be gimple.  */

      if (TREE_CODE (cond) == COND_EXPR)

      if (TREE_CODE (cond) == COND_EXPR)

        {

        {

          release_ssa_name (new_var1);

          release_ssa_name (new_var1);

          return false;

          return false;

        }

        }

      /* If COND is not something we can expect to be reducible to a GIMPLE

      /* If COND is not something we can expect to be reducible to a GIMPLE

         condition, return early.  */

         condition, return early.  */

      if (is_gimple_cast (cond))

      if (is_gimple_cast (cond))

        cond1 = TREE_OPERAND (cond, 0);

        cond1 = TREE_OPERAND (cond, 0);

      if (TREE_CODE (cond1) == TRUTH_NOT_EXPR

      if (TREE_CODE (cond1) == TRUTH_NOT_EXPR

          && !is_gimple_val (TREE_OPERAND (cond1, 0)))

          && !is_gimple_val (TREE_OPERAND (cond1, 0)))

        {

        {

          release_ssa_name (new_var1);

          release_ssa_name (new_var1);

          return false;

          return false;

        }

        }

      /* If what we get back is not gimple try to create it as gimple by

      /* If what we get back is not gimple try to create it as gimple by

         using a temporary variable.  */

         using a temporary variable.  */

      if (is_gimple_cast (cond)

      if (is_gimple_cast (cond)

          && !is_gimple_val (TREE_OPERAND (cond, 0)))

          && !is_gimple_val (TREE_OPERAND (cond, 0)))

        {

        {

          tree op0, tmp, cond_tmp;

          tree op0, tmp, cond_tmp;

          /* Only "real" casts are OK here, not everything that is

          /* Only "real" casts are OK here, not everything that is

             acceptable to is_gimple_cast.  Make sure we don't do

             acceptable to is_gimple_cast.  Make sure we don't do

             anything stupid here.  */

             anything stupid here.  */

          gcc_assert (TREE_CODE (cond) == NOP_EXPR

          gcc_assert (TREE_CODE (cond) == NOP_EXPR

                      || TREE_CODE (cond) == CONVERT_EXPR);

                      || TREE_CODE (cond) == CONVERT_EXPR);

          op0 = TREE_OPERAND (cond, 0);

          op0 = TREE_OPERAND (cond, 0);

          tmp = create_tmp_var (TREE_TYPE (op0), NULL);

          tmp = create_tmp_var (TREE_TYPE (op0), NULL);

          add_referenced_var (tmp);

          add_referenced_var (tmp);

          cond_tmp = make_ssa_name (tmp, NULL);

          cond_tmp = make_ssa_name (tmp, NULL);

          new = build2 (MODIFY_EXPR, TREE_TYPE (cond_tmp), cond_tmp, op0);

          new = build2 (MODIFY_EXPR, TREE_TYPE (cond_tmp), cond_tmp, op0);

          SSA_NAME_DEF_STMT (cond_tmp) = new;

          SSA_NAME_DEF_STMT (cond_tmp) = new;

          bsi_insert_after (&bsi, new, BSI_NEW_STMT);

          bsi_insert_after (&bsi, new, BSI_NEW_STMT);

          cond = fold_convert (TREE_TYPE (result), cond_tmp);

          cond = fold_convert (TREE_TYPE (result), cond_tmp);

        }

        }

      new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond);

      new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond);

    }

    }

  bsi_insert_after (&bsi, new, BSI_NEW_STMT);

  bsi_insert_after (&bsi, new, BSI_NEW_STMT);

  SSA_NAME_DEF_STMT (new_var1) = new;

  SSA_NAME_DEF_STMT (new_var1) = new;

  replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1);

  replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1);

  /* Note that we optimized this PHI.  */

  /* Note that we optimized this PHI.  */

  return true;

  return true;

}

}

/*  The function value_replacement does the main work of doing the value

/*  The function value_replacement does the main work of doing the value

    replacement.  Return true if the replacement is done.  Otherwise return

    replacement.  Return true if the replacement is done.  Otherwise return

    false.

    false.

    BB is the basic block where the replacement is going to be done on.  ARG0

    BB is the basic block where the replacement is going to be done on.  ARG0

    is argument 0 from the PHI.  Likewise for ARG1.  */

    is argument 0 from the PHI.  Likewise for ARG1.  */

static bool

static bool

value_replacement (basic_block cond_bb, basic_block middle_bb,

value_replacement (basic_block cond_bb, basic_block middle_bb,

                   edge e0, edge e1, tree phi,

                   edge e0, edge e1, tree phi,

                   tree arg0, tree arg1)

                   tree arg0, tree arg1)

{

{

  tree cond;

  tree cond;

  edge true_edge, false_edge;

  edge true_edge, false_edge;

  /* If the type says honor signed zeros we cannot do this

  /* If the type says honor signed zeros we cannot do this

     optimization.  */

     optimization.  */

  if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))

  if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))

    return false;

    return false;

  if (!empty_block_p (middle_bb))

  if (!empty_block_p (middle_bb))

    return false;

    return false;

  cond = COND_EXPR_COND (last_stmt (cond_bb));

  cond = COND_EXPR_COND (last_stmt (cond_bb));

  /* This transformation is only valid for equality comparisons.  */

  /* This transformation is only valid for equality comparisons.  */

  if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR)

  if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR)

    return false;

    return false;

  /* We need to know which is the true edge and which is the false

  /* We need to know which is the true edge and which is the false

      edge so that we know if have abs or negative abs.  */

      edge so that we know if have abs or negative abs.  */

  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);

  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);

  /* At this point we know we have a COND_EXPR with two successors.

  /* At this point we know we have a COND_EXPR with two successors.

     One successor is BB, the other successor is an empty block which

     One successor is BB, the other successor is an empty block which

     falls through into BB.

     falls through into BB.

     The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.

     The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.

     There is a single PHI node at the join point (BB) with two arguments.

     There is a single PHI node at the join point (BB) with two arguments.

     We now need to verify that the two arguments in the PHI node match

     We now need to verify that the two arguments in the PHI node match

     the two arguments to the equality comparison.  */

     the two arguments to the equality comparison.  */

  if ((operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 0))

  if ((operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 0))

       && operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 1)))

       && operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 1)))

      || (operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 0))

      || (operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 0))

          && operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 1))))

          && operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 1))))

    {

    {

      edge e;

      edge e;

      tree arg;

      tree arg;

      /* For NE_EXPR, we want to build an assignment result = arg where

      /* For NE_EXPR, we want to build an assignment result = arg where

         arg is the PHI argument associated with the true edge.  For