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[/] [openrisc/] [tags/] [gnu-src/] [gcc-4.5.1/] [gcc-4.5.1-or32-1.0rc2/] [gcc/] [tree-ssa-sink.c] - Diff between revs 280 and 384

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/* Code sinking for trees
/* Code sinking for trees
   Copyright (C) 2001, 2002, 2003, 2004, 2007, 2008, 2009
   Copyright (C) 2001, 2002, 2003, 2004, 2007, 2008, 2009
   Free Software Foundation, Inc.
   Free Software Foundation, Inc.
   Contributed by Daniel Berlin <dan@dberlin.org>
   Contributed by Daniel Berlin <dan@dberlin.org>
 
 
This file is part of GCC.
This file is part of GCC.
 
 
GCC is free software; you can redistribute it and/or modify
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
the Free Software Foundation; either version 3, or (at your option)
any later version.
any later version.
 
 
GCC is distributed in the hope that it will be useful,
GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
GNU General Public License 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 "basic-block.h"
#include "basic-block.h"
#include "diagnostic.h"
#include "diagnostic.h"
#include "tree-inline.h"
#include "tree-inline.h"
#include "tree-flow.h"
#include "tree-flow.h"
#include "gimple.h"
#include "gimple.h"
#include "tree-dump.h"
#include "tree-dump.h"
#include "timevar.h"
#include "timevar.h"
#include "fibheap.h"
#include "fibheap.h"
#include "hashtab.h"
#include "hashtab.h"
#include "tree-iterator.h"
#include "tree-iterator.h"
#include "real.h"
#include "real.h"
#include "alloc-pool.h"
#include "alloc-pool.h"
#include "tree-pass.h"
#include "tree-pass.h"
#include "flags.h"
#include "flags.h"
#include "bitmap.h"
#include "bitmap.h"
#include "langhooks.h"
#include "langhooks.h"
#include "cfgloop.h"
#include "cfgloop.h"
 
 
/* TODO:
/* TODO:
   1. Sinking store only using scalar promotion (IE without moving the RHS):
   1. Sinking store only using scalar promotion (IE without moving the RHS):
 
 
   *q = p;
   *q = p;
   p = p + 1;
   p = p + 1;
   if (something)
   if (something)
     *q = <not p>;
     *q = <not p>;
   else
   else
     y = *q;
     y = *q;
 
 
 
 
   should become
   should become
   sinktemp = p;
   sinktemp = p;
   p = p + 1;
   p = p + 1;
   if (something)
   if (something)
     *q = <not p>;
     *q = <not p>;
   else
   else
   {
   {
     *q = sinktemp;
     *q = sinktemp;
     y = *q
     y = *q
   }
   }
   Store copy propagation will take care of the store elimination above.
   Store copy propagation will take care of the store elimination above.
 
 
 
 
   2. Sinking using Partial Dead Code Elimination.  */
   2. Sinking using Partial Dead Code Elimination.  */
 
 
 
 
static struct
static struct
{
{
  /* The number of statements sunk down the flowgraph by code sinking.  */
  /* The number of statements sunk down the flowgraph by code sinking.  */
  int sunk;
  int sunk;
 
 
} sink_stats;
} sink_stats;
 
 
 
 
/* Given a PHI, and one of its arguments (DEF), find the edge for
/* Given a PHI, and one of its arguments (DEF), find the edge for
   that argument and return it.  If the argument occurs twice in the PHI node,
   that argument and return it.  If the argument occurs twice in the PHI node,
   we return NULL.  */
   we return NULL.  */
 
 
static basic_block
static basic_block
find_bb_for_arg (gimple phi, tree def)
find_bb_for_arg (gimple phi, tree def)
{
{
  size_t i;
  size_t i;
  bool foundone = false;
  bool foundone = false;
  basic_block result = NULL;
  basic_block result = NULL;
  for (i = 0; i < gimple_phi_num_args (phi); i++)
  for (i = 0; i < gimple_phi_num_args (phi); i++)
    if (PHI_ARG_DEF (phi, i) == def)
    if (PHI_ARG_DEF (phi, i) == def)
      {
      {
        if (foundone)
        if (foundone)
          return NULL;
          return NULL;
        foundone = true;
        foundone = true;
        result = gimple_phi_arg_edge (phi, i)->src;
        result = gimple_phi_arg_edge (phi, i)->src;
      }
      }
  return result;
  return result;
}
}
 
 
/* When the first immediate use is in a statement, then return true if all
/* When the first immediate use is in a statement, then return true if all
   immediate uses in IMM are in the same statement.
   immediate uses in IMM are in the same statement.
   We could also do the case where  the first immediate use is in a phi node,
   We could also do the case where  the first immediate use is in a phi node,
   and all the other uses are in phis in the same basic block, but this
   and all the other uses are in phis in the same basic block, but this
   requires some expensive checking later (you have to make sure no def/vdef
   requires some expensive checking later (you have to make sure no def/vdef
   in the statement occurs for multiple edges in the various phi nodes it's
   in the statement occurs for multiple edges in the various phi nodes it's
   used in, so that you only have one place you can sink it to.  */
   used in, so that you only have one place you can sink it to.  */
 
 
static bool
static bool
all_immediate_uses_same_place (gimple stmt)
all_immediate_uses_same_place (gimple stmt)
{
{
  gimple firstuse = NULL;
  gimple firstuse = NULL;
  ssa_op_iter op_iter;
  ssa_op_iter op_iter;
  imm_use_iterator imm_iter;
  imm_use_iterator imm_iter;
  use_operand_p use_p;
  use_operand_p use_p;
  tree var;
  tree var;
 
 
  FOR_EACH_SSA_TREE_OPERAND (var, stmt, op_iter, SSA_OP_ALL_DEFS)
  FOR_EACH_SSA_TREE_OPERAND (var, stmt, op_iter, SSA_OP_ALL_DEFS)
    {
    {
      FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
      FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
        {
        {
          if (is_gimple_debug (USE_STMT (use_p)))
          if (is_gimple_debug (USE_STMT (use_p)))
            continue;
            continue;
          if (firstuse == NULL)
          if (firstuse == NULL)
            firstuse = USE_STMT (use_p);
            firstuse = USE_STMT (use_p);
          else
          else
            if (firstuse != USE_STMT (use_p))
            if (firstuse != USE_STMT (use_p))
              return false;
              return false;
        }
        }
    }
    }
 
 
  return true;
  return true;
}
}
 
 
/* Some global stores don't necessarily have VDEF's of global variables,
/* Some global stores don't necessarily have VDEF's of global variables,
   but we still must avoid moving them around.  */
   but we still must avoid moving them around.  */
 
 
bool
bool
is_hidden_global_store (gimple stmt)
is_hidden_global_store (gimple stmt)
{
{
  /* Check virtual definitions.  If we get here, the only virtual
  /* Check virtual definitions.  If we get here, the only virtual
     definitions we should see are those generated by assignment or call
     definitions we should see are those generated by assignment or call
     statements.  */
     statements.  */
  if (gimple_vdef (stmt))
  if (gimple_vdef (stmt))
    {
    {
      tree lhs;
      tree lhs;
 
 
      gcc_assert (is_gimple_assign (stmt) || is_gimple_call (stmt));
      gcc_assert (is_gimple_assign (stmt) || is_gimple_call (stmt));
 
 
      /* Note that we must not check the individual virtual operands
      /* Note that we must not check the individual virtual operands
         here.  In particular, if this is an aliased store, we could
         here.  In particular, if this is an aliased store, we could
         end up with something like the following (SSA notation
         end up with something like the following (SSA notation
         redacted for brevity):
         redacted for brevity):
 
 
                foo (int *p, int i)
                foo (int *p, int i)
                {
                {
                  int x;
                  int x;
                  p_1 = (i_2 > 3) ? &x : p;
                  p_1 = (i_2 > 3) ? &x : p;
 
 
                  # x_4 = VDEF <x_3>
                  # x_4 = VDEF <x_3>
                  *p_1 = 5;
                  *p_1 = 5;
 
 
                  return 2;
                  return 2;
                }
                }
 
 
         Notice that the store to '*p_1' should be preserved, if we
         Notice that the store to '*p_1' should be preserved, if we
         were to check the virtual definitions in that store, we would
         were to check the virtual definitions in that store, we would
         not mark it needed.  This is because 'x' is not a global
         not mark it needed.  This is because 'x' is not a global
         variable.
         variable.
 
 
         Therefore, we check the base address of the LHS.  If the
         Therefore, we check the base address of the LHS.  If the
         address is a pointer, we check if its name tag or symbol tag is
         address is a pointer, we check if its name tag or symbol tag is
         a global variable.  Otherwise, we check if the base variable
         a global variable.  Otherwise, we check if the base variable
         is a global.  */
         is a global.  */
      lhs = gimple_get_lhs (stmt);
      lhs = gimple_get_lhs (stmt);
 
 
      if (REFERENCE_CLASS_P (lhs))
      if (REFERENCE_CLASS_P (lhs))
        lhs = get_base_address (lhs);
        lhs = get_base_address (lhs);
 
 
      if (lhs == NULL_TREE)
      if (lhs == NULL_TREE)
        {
        {
          /* If LHS is NULL, it means that we couldn't get the base
          /* If LHS is NULL, it means that we couldn't get the base
             address of the reference.  In which case, we should not
             address of the reference.  In which case, we should not
             move this store.  */
             move this store.  */
          return true;
          return true;
        }
        }
      else if (DECL_P (lhs))
      else if (DECL_P (lhs))
        {
        {
          /* If the store is to a global symbol, we need to keep it.  */
          /* If the store is to a global symbol, we need to keep it.  */
          if (is_global_var (lhs))
          if (is_global_var (lhs))
            return true;
            return true;
 
 
        }
        }
      else if (INDIRECT_REF_P (lhs))
      else if (INDIRECT_REF_P (lhs))
        return ptr_deref_may_alias_global_p (TREE_OPERAND (lhs, 0));
        return ptr_deref_may_alias_global_p (TREE_OPERAND (lhs, 0));
      else
      else
        gcc_unreachable ();
        gcc_unreachable ();
    }
    }
 
 
  return false;
  return false;
}
}
 
 
/* Find the nearest common dominator of all of the immediate uses in IMM.  */
/* Find the nearest common dominator of all of the immediate uses in IMM.  */
 
 
static basic_block
static basic_block
nearest_common_dominator_of_uses (gimple stmt, bool *debug_stmts)
nearest_common_dominator_of_uses (gimple stmt, bool *debug_stmts)
{
{
  bitmap blocks = BITMAP_ALLOC (NULL);
  bitmap blocks = BITMAP_ALLOC (NULL);
  basic_block commondom;
  basic_block commondom;
  unsigned int j;
  unsigned int j;
  bitmap_iterator bi;
  bitmap_iterator bi;
  ssa_op_iter op_iter;
  ssa_op_iter op_iter;
  imm_use_iterator imm_iter;
  imm_use_iterator imm_iter;
  use_operand_p use_p;
  use_operand_p use_p;
  tree var;
  tree var;
 
 
  bitmap_clear (blocks);
  bitmap_clear (blocks);
  FOR_EACH_SSA_TREE_OPERAND (var, stmt, op_iter, SSA_OP_ALL_DEFS)
  FOR_EACH_SSA_TREE_OPERAND (var, stmt, op_iter, SSA_OP_ALL_DEFS)
    {
    {
      FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
      FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
        {
        {
          gimple usestmt = USE_STMT (use_p);
          gimple usestmt = USE_STMT (use_p);
          basic_block useblock;
          basic_block useblock;
 
 
          if (gimple_code (usestmt) == GIMPLE_PHI)
          if (gimple_code (usestmt) == GIMPLE_PHI)
            {
            {
              int idx = PHI_ARG_INDEX_FROM_USE (use_p);
              int idx = PHI_ARG_INDEX_FROM_USE (use_p);
 
 
              useblock = gimple_phi_arg_edge (usestmt, idx)->src;
              useblock = gimple_phi_arg_edge (usestmt, idx)->src;
            }
            }
          else if (is_gimple_debug (usestmt))
          else if (is_gimple_debug (usestmt))
            {
            {
              *debug_stmts = true;
              *debug_stmts = true;
              continue;
              continue;
            }
            }
          else
          else
            {
            {
              useblock = gimple_bb (usestmt);
              useblock = gimple_bb (usestmt);
            }
            }
 
 
          /* Short circuit. Nothing dominates the entry block.  */
          /* Short circuit. Nothing dominates the entry block.  */
          if (useblock == ENTRY_BLOCK_PTR)
          if (useblock == ENTRY_BLOCK_PTR)
            {
            {
              BITMAP_FREE (blocks);
              BITMAP_FREE (blocks);
              return NULL;
              return NULL;
            }
            }
          bitmap_set_bit (blocks, useblock->index);
          bitmap_set_bit (blocks, useblock->index);
        }
        }
    }
    }
  commondom = BASIC_BLOCK (bitmap_first_set_bit (blocks));
  commondom = BASIC_BLOCK (bitmap_first_set_bit (blocks));
  EXECUTE_IF_SET_IN_BITMAP (blocks, 0, j, bi)
  EXECUTE_IF_SET_IN_BITMAP (blocks, 0, j, bi)
    commondom = nearest_common_dominator (CDI_DOMINATORS, commondom,
    commondom = nearest_common_dominator (CDI_DOMINATORS, commondom,
                                          BASIC_BLOCK (j));
                                          BASIC_BLOCK (j));
  BITMAP_FREE (blocks);
  BITMAP_FREE (blocks);
  return commondom;
  return commondom;
}
}
 
 
/* Given a statement (STMT) and the basic block it is currently in (FROMBB),
/* Given a statement (STMT) and the basic block it is currently in (FROMBB),
   determine the location to sink the statement to, if any.
   determine the location to sink the statement to, if any.
   Returns true if there is such location; in that case, TOGSI points to the
   Returns true if there is such location; in that case, TOGSI points to the
   statement before that STMT should be moved.  */
   statement before that STMT should be moved.  */
 
 
static bool
static bool
statement_sink_location (gimple stmt, basic_block frombb,
statement_sink_location (gimple stmt, basic_block frombb,
                         gimple_stmt_iterator *togsi)
                         gimple_stmt_iterator *togsi)
{
{
  gimple use;
  gimple use;
  tree def;
  tree def;
  use_operand_p one_use = NULL_USE_OPERAND_P;
  use_operand_p one_use = NULL_USE_OPERAND_P;
  basic_block sinkbb;
  basic_block sinkbb;
  use_operand_p use_p;
  use_operand_p use_p;
  def_operand_p def_p;
  def_operand_p def_p;
  ssa_op_iter iter;
  ssa_op_iter iter;
  imm_use_iterator imm_iter;
  imm_use_iterator imm_iter;
 
 
  FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
  FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
    {
    {
      FOR_EACH_IMM_USE_FAST (one_use, imm_iter, def)
      FOR_EACH_IMM_USE_FAST (one_use, imm_iter, def)
        {
        {
          if (is_gimple_debug (USE_STMT (one_use)))
          if (is_gimple_debug (USE_STMT (one_use)))
            continue;
            continue;
 
 
          break;
          break;
        }
        }
      if (one_use != NULL_USE_OPERAND_P)
      if (one_use != NULL_USE_OPERAND_P)
        break;
        break;
    }
    }
 
 
  /* Return if there are no immediate uses of this stmt.  */
  /* Return if there are no immediate uses of this stmt.  */
  if (one_use == NULL_USE_OPERAND_P)
  if (one_use == NULL_USE_OPERAND_P)
    return false;
    return false;
 
 
  if (gimple_code (stmt) != GIMPLE_ASSIGN)
  if (gimple_code (stmt) != GIMPLE_ASSIGN)
    return false;
    return false;
 
 
  /* There are a few classes of things we can't or don't move, some because we
  /* There are a few classes of things we can't or don't move, some because we
     don't have code to handle it, some because it's not profitable and some
     don't have code to handle it, some because it's not profitable and some
     because it's not legal.
     because it's not legal.
 
 
     We can't sink things that may be global stores, at least not without
     We can't sink things that may be global stores, at least not without
     calculating a lot more information, because we may cause it to no longer
     calculating a lot more information, because we may cause it to no longer
     be seen by an external routine that needs it depending on where it gets
     be seen by an external routine that needs it depending on where it gets
     moved to.
     moved to.
 
 
     We don't want to sink loads from memory.
     We don't want to sink loads from memory.
 
 
     We can't sink statements that end basic blocks without splitting the
     We can't sink statements that end basic blocks without splitting the
     incoming edge for the sink location to place it there.
     incoming edge for the sink location to place it there.
 
 
     We can't sink statements that have volatile operands.
     We can't sink statements that have volatile operands.
 
 
     We don't want to sink dead code, so anything with 0 immediate uses is not
     We don't want to sink dead code, so anything with 0 immediate uses is not
     sunk.
     sunk.
 
 
     Don't sink BLKmode assignments if current function has any local explicit
     Don't sink BLKmode assignments if current function has any local explicit
     register variables, as BLKmode assignments may involve memcpy or memset
     register variables, as BLKmode assignments may involve memcpy or memset
     calls or, on some targets, inline expansion thereof that sometimes need
     calls or, on some targets, inline expansion thereof that sometimes need
     to use specific hard registers.
     to use specific hard registers.
 
 
  */
  */
  if (stmt_ends_bb_p (stmt)
  if (stmt_ends_bb_p (stmt)
      || gimple_has_side_effects (stmt)
      || gimple_has_side_effects (stmt)
      || is_hidden_global_store (stmt)
      || is_hidden_global_store (stmt)
      || gimple_has_volatile_ops (stmt)
      || gimple_has_volatile_ops (stmt)
      || gimple_vuse (stmt)
      || gimple_vuse (stmt)
      || (cfun->has_local_explicit_reg_vars
      || (cfun->has_local_explicit_reg_vars
          && TYPE_MODE (TREE_TYPE (gimple_assign_lhs (stmt))) == BLKmode))
          && TYPE_MODE (TREE_TYPE (gimple_assign_lhs (stmt))) == BLKmode))
    return false;
    return false;
 
 
  FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS)
  FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS)
    {
    {
      tree def = DEF_FROM_PTR (def_p);
      tree def = DEF_FROM_PTR (def_p);
      if (is_global_var (SSA_NAME_VAR (def))
      if (is_global_var (SSA_NAME_VAR (def))
          || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def))
          || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def))
        return false;
        return false;
    }
    }
 
 
  FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)
  FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)
    {
    {
      tree use = USE_FROM_PTR (use_p);
      tree use = USE_FROM_PTR (use_p);
      if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (use))
      if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (use))
        return false;
        return false;
    }
    }
 
 
  /* If all the immediate uses are not in the same place, find the nearest
  /* If all the immediate uses are not in the same place, find the nearest
     common dominator of all the immediate uses.  For PHI nodes, we have to
     common dominator of all the immediate uses.  For PHI nodes, we have to
     find the nearest common dominator of all of the predecessor blocks, since
     find the nearest common dominator of all of the predecessor blocks, since
     that is where insertion would have to take place.  */
     that is where insertion would have to take place.  */
  if (!all_immediate_uses_same_place (stmt))
  if (!all_immediate_uses_same_place (stmt))
    {
    {
      bool debug_stmts = false;
      bool debug_stmts = false;
      basic_block commondom = nearest_common_dominator_of_uses (stmt,
      basic_block commondom = nearest_common_dominator_of_uses (stmt,
                                                                &debug_stmts);
                                                                &debug_stmts);
 
 
      if (commondom == frombb)
      if (commondom == frombb)
        return false;
        return false;
 
 
      /* Our common dominator has to be dominated by frombb in order to be a
      /* Our common dominator has to be dominated by frombb in order to be a
         trivially safe place to put this statement, since it has multiple
         trivially safe place to put this statement, since it has multiple
         uses.  */
         uses.  */
      if (!dominated_by_p (CDI_DOMINATORS, commondom, frombb))
      if (!dominated_by_p (CDI_DOMINATORS, commondom, frombb))
        return false;
        return false;
 
 
      /* It doesn't make sense to move to a dominator that post-dominates
      /* It doesn't make sense to move to a dominator that post-dominates
         frombb, because it means we've just moved it into a path that always
         frombb, because it means we've just moved it into a path that always
         executes if frombb executes, instead of reducing the number of
         executes if frombb executes, instead of reducing the number of
         executions .  */
         executions .  */
      if (dominated_by_p (CDI_POST_DOMINATORS, frombb, commondom))
      if (dominated_by_p (CDI_POST_DOMINATORS, frombb, commondom))
        {
        {
          if (dump_file && (dump_flags & TDF_DETAILS))
          if (dump_file && (dump_flags & TDF_DETAILS))
            fprintf (dump_file, "Not moving store, common dominator post-dominates from block.\n");
            fprintf (dump_file, "Not moving store, common dominator post-dominates from block.\n");
          return false;
          return false;
        }
        }
 
 
      if (commondom == frombb || commondom->loop_depth > frombb->loop_depth)
      if (commondom == frombb || commondom->loop_depth > frombb->loop_depth)
        return false;
        return false;
      if (dump_file && (dump_flags & TDF_DETAILS))
      if (dump_file && (dump_flags & TDF_DETAILS))
        {
        {
          fprintf (dump_file, "Common dominator of all uses is %d\n",
          fprintf (dump_file, "Common dominator of all uses is %d\n",
                   commondom->index);
                   commondom->index);
        }
        }
 
 
      *togsi = gsi_after_labels (commondom);
      *togsi = gsi_after_labels (commondom);
 
 
      return true;
      return true;
    }
    }
 
 
  use = USE_STMT (one_use);
  use = USE_STMT (one_use);
  if (gimple_code (use) != GIMPLE_PHI)
  if (gimple_code (use) != GIMPLE_PHI)
    {
    {
      sinkbb = gimple_bb (use);
      sinkbb = gimple_bb (use);
      if (sinkbb == frombb || sinkbb->loop_depth > frombb->loop_depth
      if (sinkbb == frombb || sinkbb->loop_depth > frombb->loop_depth
          || sinkbb->loop_father != frombb->loop_father)
          || sinkbb->loop_father != frombb->loop_father)
        return false;
        return false;
 
 
      /* Move the expression to a post dominator can't reduce the number of
      /* Move the expression to a post dominator can't reduce the number of
         executions.  */
         executions.  */
      if (dominated_by_p (CDI_POST_DOMINATORS, frombb, sinkbb))
      if (dominated_by_p (CDI_POST_DOMINATORS, frombb, sinkbb))
        return false;
        return false;
 
 
      *togsi = gsi_for_stmt (use);
      *togsi = gsi_for_stmt (use);
 
 
      return true;
      return true;
    }
    }
 
 
  /* Note that at this point, all uses must be in the same statement, so it
  /* Note that at this point, all uses must be in the same statement, so it
     doesn't matter which def op we choose, pick the first one.  */
     doesn't matter which def op we choose, pick the first one.  */
  FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
  FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
    break;
    break;
 
 
  sinkbb = find_bb_for_arg (use, def);
  sinkbb = find_bb_for_arg (use, def);
  if (!sinkbb)
  if (!sinkbb)
    return false;
    return false;
 
 
  /* This will happen when you have
  /* This will happen when you have
     a_3 = PHI <a_13, a_26>
     a_3 = PHI <a_13, a_26>
 
 
     a_26 = VDEF <a_3>
     a_26 = VDEF <a_3>
 
 
     If the use is a phi, and is in the same bb as the def,
     If the use is a phi, and is in the same bb as the def,
     we can't sink it.  */
     we can't sink it.  */
 
 
  if (gimple_bb (use) == frombb)
  if (gimple_bb (use) == frombb)
    return false;
    return false;
  if (sinkbb == frombb || sinkbb->loop_depth > frombb->loop_depth
  if (sinkbb == frombb || sinkbb->loop_depth > frombb->loop_depth
      || sinkbb->loop_father != frombb->loop_father)
      || sinkbb->loop_father != frombb->loop_father)
    return false;
    return false;
 
 
  /* Move the expression to a post dominator can't reduce the number of
  /* Move the expression to a post dominator can't reduce the number of
     executions.  */
     executions.  */
  if (dominated_by_p (CDI_POST_DOMINATORS, frombb, sinkbb))
  if (dominated_by_p (CDI_POST_DOMINATORS, frombb, sinkbb))
    return false;
    return false;
 
 
  *togsi = gsi_after_labels (sinkbb);
  *togsi = gsi_after_labels (sinkbb);
 
 
  return true;
  return true;
}
}
 
 
/* Perform code sinking on BB */
/* Perform code sinking on BB */
 
 
static void
static void
sink_code_in_bb (basic_block bb)
sink_code_in_bb (basic_block bb)
{
{
  basic_block son;
  basic_block son;
  gimple_stmt_iterator gsi;
  gimple_stmt_iterator gsi;
  edge_iterator ei;
  edge_iterator ei;
  edge e;
  edge e;
  bool last = true;
  bool last = true;
 
 
  /* If this block doesn't dominate anything, there can't be any place to sink
  /* If this block doesn't dominate anything, there can't be any place to sink
     the statements to.  */
     the statements to.  */
  if (first_dom_son (CDI_DOMINATORS, bb) == NULL)
  if (first_dom_son (CDI_DOMINATORS, bb) == NULL)
    goto earlyout;
    goto earlyout;
 
 
  /* We can't move things across abnormal edges, so don't try.  */
  /* We can't move things across abnormal edges, so don't try.  */
  FOR_EACH_EDGE (e, ei, bb->succs)
  FOR_EACH_EDGE (e, ei, bb->succs)
    if (e->flags & EDGE_ABNORMAL)
    if (e->flags & EDGE_ABNORMAL)
      goto earlyout;
      goto earlyout;
 
 
  for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi);)
  for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi);)
    {
    {
      gimple stmt = gsi_stmt (gsi);
      gimple stmt = gsi_stmt (gsi);
      gimple_stmt_iterator togsi;
      gimple_stmt_iterator togsi;
 
 
      if (!statement_sink_location (stmt, bb, &togsi))
      if (!statement_sink_location (stmt, bb, &togsi))
        {
        {
          if (!gsi_end_p (gsi))
          if (!gsi_end_p (gsi))
            gsi_prev (&gsi);
            gsi_prev (&gsi);
          last = false;
          last = false;
          continue;
          continue;
        }
        }
      if (dump_file)
      if (dump_file)
        {
        {
          fprintf (dump_file, "Sinking ");
          fprintf (dump_file, "Sinking ");
          print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS);
          print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS);
          fprintf (dump_file, " from bb %d to bb %d\n",
          fprintf (dump_file, " from bb %d to bb %d\n",
                   bb->index, (gsi_bb (togsi))->index);
                   bb->index, (gsi_bb (togsi))->index);
        }
        }
 
 
      /* If this is the end of the basic block, we need to insert at the end
      /* If this is the end of the basic block, we need to insert at the end
         of the basic block.  */
         of the basic block.  */
      if (gsi_end_p (togsi))
      if (gsi_end_p (togsi))
        gsi_move_to_bb_end (&gsi, gsi_bb (togsi));
        gsi_move_to_bb_end (&gsi, gsi_bb (togsi));
      else
      else
        gsi_move_before (&gsi, &togsi);
        gsi_move_before (&gsi, &togsi);
 
 
      sink_stats.sunk++;
      sink_stats.sunk++;
 
 
      /* If we've just removed the last statement of the BB, the
      /* If we've just removed the last statement of the BB, the
         gsi_end_p() test below would fail, but gsi_prev() would have
         gsi_end_p() test below would fail, but gsi_prev() would have
         succeeded, and we want it to succeed.  So we keep track of
         succeeded, and we want it to succeed.  So we keep track of
         whether we're at the last statement and pick up the new last
         whether we're at the last statement and pick up the new last
         statement.  */
         statement.  */
      if (last)
      if (last)
        {
        {
          gsi = gsi_last_bb (bb);
          gsi = gsi_last_bb (bb);
          continue;
          continue;
        }
        }
 
 
      last = false;
      last = false;
      if (!gsi_end_p (gsi))
      if (!gsi_end_p (gsi))
        gsi_prev (&gsi);
        gsi_prev (&gsi);
 
 
    }
    }
 earlyout:
 earlyout:
  for (son = first_dom_son (CDI_POST_DOMINATORS, bb);
  for (son = first_dom_son (CDI_POST_DOMINATORS, bb);
       son;
       son;
       son = next_dom_son (CDI_POST_DOMINATORS, son))
       son = next_dom_son (CDI_POST_DOMINATORS, son))
    {
    {
      sink_code_in_bb (son);
      sink_code_in_bb (son);
    }
    }
}
}
 
 
/* Perform code sinking.
/* Perform code sinking.
   This moves code down the flowgraph when we know it would be
   This moves code down the flowgraph when we know it would be
   profitable to do so, or it wouldn't increase the number of
   profitable to do so, or it wouldn't increase the number of
   executions of the statement.
   executions of the statement.
 
 
   IE given
   IE given
 
 
   a_1 = b + c;
   a_1 = b + c;
   if (<something>)
   if (<something>)
   {
   {
   }
   }
   else
   else
   {
   {
     foo (&b, &c);
     foo (&b, &c);
     a_5 = b + c;
     a_5 = b + c;
   }
   }
   a_6 = PHI (a_5, a_1);
   a_6 = PHI (a_5, a_1);
   USE a_6.
   USE a_6.
 
 
   we'll transform this into:
   we'll transform this into:
 
 
   if (<something>)
   if (<something>)
   {
   {
      a_1 = b + c;
      a_1 = b + c;
   }
   }
   else
   else
   {
   {
      foo (&b, &c);
      foo (&b, &c);
      a_5 = b + c;
      a_5 = b + c;
   }
   }
   a_6 = PHI (a_5, a_1);
   a_6 = PHI (a_5, a_1);
   USE a_6.
   USE a_6.
 
 
   Note that this reduces the number of computations of a = b + c to 1
   Note that this reduces the number of computations of a = b + c to 1
   when we take the else edge, instead of 2.
   when we take the else edge, instead of 2.
*/
*/
static void
static void
execute_sink_code (void)
execute_sink_code (void)
{
{
  loop_optimizer_init (LOOPS_NORMAL);
  loop_optimizer_init (LOOPS_NORMAL);
 
 
  connect_infinite_loops_to_exit ();
  connect_infinite_loops_to_exit ();
  memset (&sink_stats, 0, sizeof (sink_stats));
  memset (&sink_stats, 0, sizeof (sink_stats));
  calculate_dominance_info (CDI_DOMINATORS);
  calculate_dominance_info (CDI_DOMINATORS);
  calculate_dominance_info (CDI_POST_DOMINATORS);
  calculate_dominance_info (CDI_POST_DOMINATORS);
  sink_code_in_bb (EXIT_BLOCK_PTR);
  sink_code_in_bb (EXIT_BLOCK_PTR);
  statistics_counter_event (cfun, "Sunk statements", sink_stats.sunk);
  statistics_counter_event (cfun, "Sunk statements", sink_stats.sunk);
  free_dominance_info (CDI_POST_DOMINATORS);
  free_dominance_info (CDI_POST_DOMINATORS);
  remove_fake_exit_edges ();
  remove_fake_exit_edges ();
  loop_optimizer_finalize ();
  loop_optimizer_finalize ();
}
}
 
 
/* Gate and execute functions for PRE.  */
/* Gate and execute functions for PRE.  */
 
 
static unsigned int
static unsigned int
do_sink (void)
do_sink (void)
{
{
  execute_sink_code ();
  execute_sink_code ();
  return 0;
  return 0;
}
}
 
 
static bool
static bool
gate_sink (void)
gate_sink (void)
{
{
  return flag_tree_sink != 0;
  return flag_tree_sink != 0;
}
}
 
 
struct gimple_opt_pass pass_sink_code =
struct gimple_opt_pass pass_sink_code =
{
{
 {
 {
  GIMPLE_PASS,
  GIMPLE_PASS,
  "sink",                               /* name */
  "sink",                               /* name */
  gate_sink,                            /* gate */
  gate_sink,                            /* gate */
  do_sink,                              /* execute */
  do_sink,                              /* execute */
  NULL,                                 /* sub */
  NULL,                                 /* sub */
  NULL,                                 /* next */
  NULL,                                 /* next */
  0,                                     /* static_pass_number */
  0,                                     /* static_pass_number */
  TV_TREE_SINK,                         /* tv_id */
  TV_TREE_SINK,                         /* tv_id */
  PROP_no_crit_edges | PROP_cfg
  PROP_no_crit_edges | PROP_cfg
    | PROP_ssa,                         /* properties_required */
    | PROP_ssa,                         /* properties_required */
  0,                                     /* properties_provided */
  0,                                     /* properties_provided */
  0,                                     /* properties_destroyed */
  0,                                     /* properties_destroyed */
  0,                                     /* todo_flags_start */
  0,                                     /* todo_flags_start */
  TODO_update_ssa
  TODO_update_ssa
    | TODO_dump_func
    | TODO_dump_func
    | TODO_ggc_collect
    | TODO_ggc_collect
    | TODO_verify_ssa                   /* todo_flags_finish */
    | TODO_verify_ssa                   /* todo_flags_finish */
 }
 }
};
};
 
 

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