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downloading a git-generated archive based on the 'upstream' tag
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1 files changed, 1034 insertions, 0 deletions

diff --git a/gcc/tree-switch-conversion.c b/gcc/tree-switch-conversion.c
new file mode 100644
index 000000000..a8928e53a
--- /dev/null
+++ b/gcc/tree-switch-conversion.c
@@ -0,0 +1,1034 @@
+/* Switch Conversion converts variable initializations based on switch
+   statements to initializations from a static array.
+   Copyright (C) 2006, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+   Contributed by Martin Jambor <jamborm@suse.cz>
+
+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, write to the Free
+Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA.  */
+
+/*
+     Switch initialization conversion
+
+The following pass changes simple initializations of scalars in a switch
+statement into initializations from a static array.  Obviously, the values must
+be constant and known at compile time and a default branch must be
+provided.  For example, the following code:
+
+        int a,b;
+
+        switch (argc)
+	{
+         case 1:
+         case 2:
+                a_1 = 8;
+                b_1 = 6;
+                break;
+         case 3:
+                a_2 = 9;
+                b_2 = 5;
+                break;
+         case 12:
+                a_3 = 10;
+                b_3 = 4;
+                break;
+         default:
+                a_4 = 16;
+                b_4 = 1;
+        }
+	a_5 = PHI <a_1, a_2, a_3, a_4>
+	b_5 = PHI <b_1, b_2, b_3, b_4>
+
+
+is changed into:
+
+        static const int = CSWTCH01[] = {6, 6, 5, 1, 1, 1, 1, 1, 1, 1, 1, 4};
+        static const int = CSWTCH02[] = {8, 8, 9, 16, 16, 16, 16, 16, 16, 16,
+                                 16, 16, 10};
+
+        if (((unsigned) argc) - 1 < 11)
+          {
+	    a_6 = CSWTCH02[argc - 1];
+            b_6 = CSWTCH01[argc - 1];
+	  }
+	else
+	  {
+	    a_7 = 16;
+	    b_7 = 1;
+          }
+	  a_5 = PHI <a_6, a_7>
+	  b_b = PHI <b_6, b_7>
+
+There are further constraints.  Specifically, the range of values across all
+case labels must not be bigger than SWITCH_CONVERSION_BRANCH_RATIO (default
+eight) times the number of the actual switch branches. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "line-map.h"
+#include "params.h"
+#include "flags.h"
+#include "tree.h"
+#include "basic-block.h"
+#include "tree-flow.h"
+#include "tree-flow-inline.h"
+#include "tree-ssa-operands.h"
+#include "output.h"
+#include "input.h"
+#include "tree-pass.h"
+#include "gimple-pretty-print.h"
+#include "tree-dump.h"
+#include "timevar.h"
+#include "langhooks.h"
+
+/* The main structure of the pass.  */
+struct switch_conv_info
+{
+  /* The expression used to decide the switch branch.  (It is subsequently used
+     as the index to the created array.) */
+  tree index_expr;
+
+  /* The following integer constants store the minimum value covered by the
+     cases.  */
+  tree range_min;
+
+  /* The difference between the above two numbers, i.e. The size of the array
+     that would have to be created by the transformation.  */
+  tree range_size;
+
+  /* Basic block that contains the actual SWITCH_EXPR.  */
+  basic_block switch_bb;
+
+  /* All branches of the switch statement must have a single successor stored in
+     the following variable.  */
+  basic_block final_bb;
+
+  /* Number of phi nodes in the final bb (that we'll be replacing).  */
+  int phi_count;
+
+  /* Array of default values, in the same order as phi nodes.  */
+  tree *default_values;
+
+  /* Constructors of new static arrays.  */
+  VEC (constructor_elt, gc) **constructors;
+
+  /* Array of ssa names that are initialized with a value from a new static
+     array.  */
+  tree *target_inbound_names;
+
+  /* Array of ssa names that are initialized with the default value if the
+     switch expression is out of range.  */
+  tree *target_outbound_names;
+
+  /* The probability of the default edge in the replaced switch.  */
+  int default_prob;
+
+  /* The count of the default edge in the replaced switch.  */
+  gcov_type default_count;
+
+  /* Combined count of all other (non-default) edges in the replaced switch.  */
+  gcov_type other_count;
+
+  /* The first load statement that loads a temporary from a new static array.
+   */
+  gimple arr_ref_first;
+
+  /* The last load statement that loads a temporary from a new static array.  */
+  gimple arr_ref_last;
+
+  /* String reason why the case wasn't a good candidate that is written to the
+     dump file, if there is one.  */
+  const char *reason;
+
+  /* Parameters for expand_switch_using_bit_tests.  Should be computed
+     the same way as in expand_case.  */
+  unsigned int bit_test_uniq;
+  unsigned int bit_test_count;
+  basic_block bit_test_bb[2];
+};
+
+/* Global pass info.  */
+static struct switch_conv_info info;
+
+
+/* Checks whether the range given by individual case statements of the SWTCH
+   switch statement isn't too big and whether the number of branches actually
+   satisfies the size of the new array.  */
+
+static bool
+check_range (gimple swtch)
+{
+  tree min_case, max_case;
+  unsigned int branch_num = gimple_switch_num_labels (swtch);
+  tree range_max;
+
+  /* The gimplifier has already sorted the cases by CASE_LOW and ensured there
+     is a default label which is the first in the vector.  */
+
+  min_case = gimple_switch_label (swtch, 1);
+  info.range_min = CASE_LOW (min_case);
+
+  gcc_assert (branch_num > 1);
+  gcc_assert (CASE_LOW (gimple_switch_label (swtch, 0)) == NULL_TREE);
+  max_case = gimple_switch_label (swtch, branch_num - 1);
+  if (CASE_HIGH (max_case) != NULL_TREE)
+    range_max = CASE_HIGH (max_case);
+  else
+    range_max = CASE_LOW (max_case);
+
+  gcc_assert (info.range_min);
+  gcc_assert (range_max);
+
+  info.range_size = int_const_binop (MINUS_EXPR, range_max, info.range_min, 0);
+
+  gcc_assert (info.range_size);
+  if (!host_integerp (info.range_size, 1))
+    {
+      info.reason = "index range way too large or otherwise unusable.\n";
+      return false;
+    }
+
+  if ((unsigned HOST_WIDE_INT) tree_low_cst (info.range_size, 1)
+      > ((unsigned) branch_num * SWITCH_CONVERSION_BRANCH_RATIO))
+    {
+      info.reason = "the maximum range-branch ratio exceeded.\n";
+      return false;
+    }
+
+  return true;
+}
+
+/* Checks the given CS switch case whether it is suitable for conversion
+   (whether all but the default basic blocks are empty and so on).  If it is,
+   adds the case to the branch list along with values for the defined variables
+   and returns true.  Otherwise returns false.  */
+
+static bool
+check_process_case (tree cs)
+{
+  tree ldecl;
+  basic_block label_bb, following_bb;
+  edge e;
+
+  ldecl = CASE_LABEL (cs);
+  label_bb = label_to_block (ldecl);
+
+  e = find_edge (info.switch_bb, label_bb);
+  gcc_assert (e);
+
+  if (CASE_LOW (cs) == NULL_TREE)
+    {
+      /* Default branch.  */
+      info.default_prob = e->probability;
+      info.default_count = e->count;
+    }
+  else
+    {
+      int i;
+      info.other_count += e->count;
+      for (i = 0; i < 2; i++)
+	if (info.bit_test_bb[i] == label_bb)
+	  break;
+	else if (info.bit_test_bb[i] == NULL)
+	  {
+	    info.bit_test_bb[i] = label_bb;
+	    info.bit_test_uniq++;
+	    break;
+	  }
+      if (i == 2)
+	info.bit_test_uniq = 3;
+      if (CASE_HIGH (cs) != NULL_TREE
+	  && ! tree_int_cst_equal (CASE_LOW (cs), CASE_HIGH (cs)))
+	info.bit_test_count += 2;
+      else
+	info.bit_test_count++;
+    }
+
+  if (!label_bb)
+    {
+      info.reason = "  Bad case - cs BB  label is NULL\n";
+      return false;
+    }
+
+  if (!single_pred_p (label_bb))
+    {
+      if (info.final_bb && info.final_bb != label_bb)
+	{
+	  info.reason = "  Bad case - a non-final BB has two predecessors\n";
+	  return false; /* sth complex going on in this branch  */
+	}
+
+      following_bb = label_bb;
+    }
+  else
+    {
+      if (!empty_block_p (label_bb))
+	{
+	  info.reason = "  Bad case - a non-final BB not empty\n";
+	  return false;
+	}
+
+      e = single_succ_edge (label_bb);
+      following_bb = single_succ (label_bb);
+    }
+
+  if (!info.final_bb)
+    info.final_bb = following_bb;
+  else if (info.final_bb != following_bb)
+    {
+      info.reason = "  Bad case - different final BB\n";
+      return false; /* the only successor is not common for all the branches */
+    }
+
+  return true;
+}
+
+/* This function checks whether all required values in phi nodes in final_bb
+   are constants.  Required values are those that correspond to a basic block
+   which is a part of the examined switch statement.  It returns true if the
+   phi nodes are OK, otherwise false.  */
+
+static bool
+check_final_bb (void)
+{
+  gimple_stmt_iterator gsi;
+
+  info.phi_count = 0;
+  for (gsi = gsi_start_phis (info.final_bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      gimple phi = gsi_stmt (gsi);
+      unsigned int i;
+
+      info.phi_count++;
+
+      for (i = 0; i < gimple_phi_num_args (phi); i++)
+	{
+	  basic_block bb = gimple_phi_arg_edge (phi, i)->src;
+
+	  if (bb == info.switch_bb
+	      || (single_pred_p (bb) && single_pred (bb) == info.switch_bb))
+	    {
+	      tree reloc, val;
+
+	      val = gimple_phi_arg_def (phi, i);
+	      if (!is_gimple_ip_invariant (val))
+		{
+		  info.reason = "   Non-invariant value from a case\n";
+		  return false; /* Non-invariant argument.  */
+		}
+	      reloc = initializer_constant_valid_p (val, TREE_TYPE (val));
+	      if ((flag_pic && reloc != null_pointer_node)
+		  || (!flag_pic && reloc == NULL_TREE))
+		{
+		  if (reloc)
+		    info.reason
+		      = "   Value from a case would need runtime relocations\n";
+		  else
+		    info.reason
+		      = "   Value from a case is not a valid initializer\n";
+		  return false;
+		}
+	    }
+	}
+    }
+
+  return true;
+}
+
+/* The following function allocates default_values, target_{in,out}_names and
+   constructors arrays.  The last one is also populated with pointers to
+   vectors that will become constructors of new arrays.  */
+
+static void
+create_temp_arrays (void)
+{
+  int i;
+
+  info.default_values = XCNEWVEC (tree, info.phi_count * 3);
+  info.constructors = XCNEWVEC (VEC (constructor_elt, gc) *, info.phi_count);
+  info.target_inbound_names = info.default_values + info.phi_count;
+  info.target_outbound_names = info.target_inbound_names + info.phi_count;
+  for (i = 0; i < info.phi_count; i++)
+    info.constructors[i]
+      = VEC_alloc (constructor_elt, gc, tree_low_cst (info.range_size, 1) + 1);
+}
+
+/* Free the arrays created by create_temp_arrays().  The vectors that are
+   created by that function are not freed here, however, because they have
+   already become constructors and must be preserved.  */
+
+static void
+free_temp_arrays (void)
+{
+  XDELETEVEC (info.constructors);
+  XDELETEVEC (info.default_values);
+}
+
+/* Populate the array of default values in the order of phi nodes.
+   DEFAULT_CASE is the CASE_LABEL_EXPR for the default switch branch.  */
+
+static void
+gather_default_values (tree default_case)
+{
+  gimple_stmt_iterator gsi;
+  basic_block bb = label_to_block (CASE_LABEL (default_case));
+  edge e;
+  int i = 0;
+
+  gcc_assert (CASE_LOW (default_case) == NULL_TREE);
+
+  if (bb == info.final_bb)
+    e = find_edge (info.switch_bb, bb);
+  else
+    e = single_succ_edge (bb);
+
+  for (gsi = gsi_start_phis (info.final_bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      gimple phi = gsi_stmt (gsi);
+      tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
+      gcc_assert (val);
+      info.default_values[i++] = val;
+    }
+}
+
+/* The following function populates the vectors in the constructors array with
+   future contents of the static arrays.  The vectors are populated in the
+   order of phi nodes.  SWTCH is the switch statement being converted.  */
+
+static void
+build_constructors (gimple swtch)
+{
+  unsigned i, branch_num = gimple_switch_num_labels (swtch);
+  tree pos = info.range_min;
+
+  for (i = 1; i < branch_num; i++)
+    {
+      tree cs = gimple_switch_label (swtch, i);
+      basic_block bb = label_to_block (CASE_LABEL (cs));
+      edge e;
+      tree high;
+      gimple_stmt_iterator gsi;
+      int j;
+
+      if (bb == info.final_bb)
+	e = find_edge (info.switch_bb, bb);
+      else
+	e = single_succ_edge (bb);
+      gcc_assert (e);
+
+      while (tree_int_cst_lt (pos, CASE_LOW (cs)))
+	{
+	  int k;
+	  for (k = 0; k < info.phi_count; k++)
+	    {
+	      constructor_elt *elt;
+
+	      elt = VEC_quick_push (constructor_elt,
+				    info.constructors[k], NULL);
+	      elt->index = int_const_binop (MINUS_EXPR, pos,
+					    info.range_min, 0);
+	      elt->value = info.default_values[k];
+	    }
+
+	  pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0);
+	}
+      gcc_assert (tree_int_cst_equal (pos, CASE_LOW (cs)));
+
+      j = 0;
+      if (CASE_HIGH (cs))
+	high = CASE_HIGH (cs);
+      else
+	high = CASE_LOW (cs);
+      for (gsi = gsi_start_phis (info.final_bb);
+	   !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gimple phi = gsi_stmt (gsi);
+	  tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
+	  tree low = CASE_LOW (cs);
+	  pos = CASE_LOW (cs);
+
+	  do
+	    {
+	      constructor_elt *elt;
+
+	      elt = VEC_quick_push (constructor_elt,
+				    info.constructors[j], NULL);
+	      elt->index = int_const_binop (MINUS_EXPR, pos, info.range_min, 0);
+	      elt->value = val;
+
+	      pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0);
+	    } while (!tree_int_cst_lt (high, pos)
+		     && tree_int_cst_lt (low, pos));
+	  j++;
+	}
+    }
+}
+
+/* If all values in the constructor vector are the same, return the value.
+   Otherwise return NULL_TREE.  Not supposed to be called for empty
+   vectors.  */
+
+static tree
+constructor_contains_same_values_p (VEC (constructor_elt, gc) *vec)
+{
+  unsigned int i;
+  tree prev = NULL_TREE;
+  constructor_elt *elt;
+
+  FOR_EACH_VEC_ELT (constructor_elt, vec, i, elt)
+    {
+      if (!prev)
+	prev = elt->value;
+      else if (!operand_equal_p (elt->value, prev, OEP_ONLY_CONST))
+	return NULL_TREE;
+    }
+  return prev;
+}
+
+/* Return type which should be used for array elements, either TYPE,
+   or for integral type some smaller integral type that can still hold
+   all the constants.  */
+
+static tree
+array_value_type (gimple swtch, tree type, int num)
+{
+  unsigned int i, len = VEC_length (constructor_elt, info.constructors[num]);
+  constructor_elt *elt;
+  enum machine_mode mode;
+  int sign = 0;
+  tree smaller_type;
+
+  if (!INTEGRAL_TYPE_P (type))
+    return type;
+
+  mode = GET_CLASS_NARROWEST_MODE (GET_MODE_CLASS (TYPE_MODE (type)));
+  if (GET_MODE_SIZE (TYPE_MODE (type)) <= GET_MODE_SIZE (mode))
+    return type;
+
+  if (len < (optimize_bb_for_size_p (gimple_bb (swtch)) ? 2 : 32))
+    return type;
+
+  FOR_EACH_VEC_ELT (constructor_elt, info.constructors[num], i, elt)
+    {
+      double_int cst;
+
+      if (TREE_CODE (elt->value) != INTEGER_CST)
+	return type;
+
+      cst = TREE_INT_CST (elt->value);
+      while (1)
+	{
+	  unsigned int prec = GET_MODE_BITSIZE (mode);
+	  if (prec > HOST_BITS_PER_WIDE_INT)
+	    return type;
+
+	  if (sign >= 0
+	      && double_int_equal_p (cst, double_int_zext (cst, prec)))
+	    {
+	      if (sign == 0
+		  && double_int_equal_p (cst, double_int_sext (cst, prec)))
+		break;
+	      sign = 1;
+	      break;
+	    }
+	  if (sign <= 0
+	      && double_int_equal_p (cst, double_int_sext (cst, prec)))
+	    {
+	      sign = -1;
+	      break;
+	    }
+
+	  if (sign == 1)
+	    sign = 0;
+
+	  mode = GET_MODE_WIDER_MODE (mode);
+	  if (mode == VOIDmode
+	      || GET_MODE_SIZE (mode) >= GET_MODE_SIZE (TYPE_MODE (type)))
+	    return type;
+	}
+    }
+
+  if (sign == 0)
+    sign = TYPE_UNSIGNED (type) ? 1 : -1;
+  smaller_type = lang_hooks.types.type_for_mode (mode, sign >= 0);
+  if (GET_MODE_SIZE (TYPE_MODE (type))
+      <= GET_MODE_SIZE (TYPE_MODE (smaller_type)))
+    return type;
+
+  return smaller_type;
+}
+
+/* Create an appropriate array type and declaration and assemble a static array
+   variable.  Also create a load statement that initializes the variable in
+   question with a value from the static array.  SWTCH is the switch statement
+   being converted, NUM is the index to arrays of constructors, default values
+   and target SSA names for this particular array.  ARR_INDEX_TYPE is the type
+   of the index of the new array, PHI is the phi node of the final BB that
+   corresponds to the value that will be loaded from the created array.  TIDX
+   is an ssa name of a temporary variable holding the index for loads from the
+   new array.  */
+
+static void
+build_one_array (gimple swtch, int num, tree arr_index_type, gimple phi,
+		 tree tidx)
+{
+  tree name, cst;
+  gimple load;
+  gimple_stmt_iterator gsi = gsi_for_stmt (swtch);
+  location_t loc = gimple_location (swtch);
+
+  gcc_assert (info.default_values[num]);
+
+  name = make_ssa_name (SSA_NAME_VAR (PHI_RESULT (phi)), NULL);
+  info.target_inbound_names[num] = name;
+
+  cst = constructor_contains_same_values_p (info.constructors[num]);
+  if (cst)
+    load = gimple_build_assign (name, cst);
+  else
+    {
+      tree array_type, ctor, decl, value_type, fetch, default_type;
+
+      default_type = TREE_TYPE (info.default_values[num]);
+      value_type = array_value_type (swtch, default_type, num);
+      array_type = build_array_type (value_type, arr_index_type);
+      if (default_type != value_type)
+	{
+	  unsigned int i;
+	  constructor_elt *elt;
+
+	  FOR_EACH_VEC_ELT (constructor_elt, info.constructors[num], i, elt)
+	    elt->value = fold_convert (value_type, elt->value);
+	}
+      ctor = build_constructor (array_type, info.constructors[num]);
+      TREE_CONSTANT (ctor) = true;
+      TREE_STATIC (ctor) = true;
+
+      decl = build_decl (loc, VAR_DECL, NULL_TREE, array_type);
+      TREE_STATIC (decl) = 1;
+      DECL_INITIAL (decl) = ctor;
+
+      DECL_NAME (decl) = create_tmp_var_name ("CSWTCH");
+      DECL_ARTIFICIAL (decl) = 1;
+      TREE_CONSTANT (decl) = 1;
+      TREE_READONLY (decl) = 1;
+      add_referenced_var (decl);
+      varpool_mark_needed_node (varpool_node (decl));
+      varpool_finalize_decl (decl);
+
+      fetch = build4 (ARRAY_REF, value_type, decl, tidx, NULL_TREE,
+		      NULL_TREE);
+      if (default_type != value_type)
+	{
+	  fetch = fold_convert (default_type, fetch);
+	  fetch = force_gimple_operand_gsi (&gsi, fetch, true, NULL_TREE,
+					    true, GSI_SAME_STMT);
+	}
+      load = gimple_build_assign (name, fetch);
+    }
+
+  SSA_NAME_DEF_STMT (name) = load;
+  gsi_insert_before (&gsi, load, GSI_SAME_STMT);
+  update_stmt (load);
+  info.arr_ref_last = load;
+}
+
+/* Builds and initializes static arrays initialized with values gathered from
+   the SWTCH switch statement.  Also creates statements that load values from
+   them.  */
+
+static void
+build_arrays (gimple swtch)
+{
+  tree arr_index_type;
+  tree tidx, sub, tmp, utype;
+  gimple stmt;
+  gimple_stmt_iterator gsi;
+  int i;
+  location_t loc = gimple_location (swtch);
+
+  gsi = gsi_for_stmt (swtch);
+
+  /* Make sure we do not generate arithmetics in a subrange.  */
+  utype = TREE_TYPE (info.index_expr);
+  if (TREE_TYPE (utype))
+    utype = lang_hooks.types.type_for_mode (TYPE_MODE (TREE_TYPE (utype)), 1);
+  else
+    utype = lang_hooks.types.type_for_mode (TYPE_MODE (utype), 1);
+
+  arr_index_type = build_index_type (info.range_size);
+  tmp = create_tmp_var (utype, "csui");
+  add_referenced_var (tmp);
+  tidx = make_ssa_name (tmp, NULL);
+  sub = fold_build2_loc (loc, MINUS_EXPR, utype,
+			 fold_convert_loc (loc, utype, info.index_expr),
+			 fold_convert_loc (loc, utype, info.range_min));
+  sub = force_gimple_operand_gsi (&gsi, sub,
+				  false, NULL, true, GSI_SAME_STMT);
+  stmt = gimple_build_assign (tidx, sub);
+  SSA_NAME_DEF_STMT (tidx) = stmt;
+
+  gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
+  update_stmt (stmt);
+  info.arr_ref_first = stmt;
+
+  for (gsi = gsi_start_phis (info.final_bb), i = 0;
+       !gsi_end_p (gsi); gsi_next (&gsi), i++)
+    build_one_array (swtch, i, arr_index_type, gsi_stmt (gsi), tidx);
+}
+
+/* Generates and appropriately inserts loads of default values at the position
+   given by BSI.  Returns the last inserted statement.  */
+
+static gimple
+gen_def_assigns (gimple_stmt_iterator *gsi)
+{
+  int i;
+  gimple assign = NULL;
+
+  for (i = 0; i < info.phi_count; i++)
+    {
+      tree name
+	= make_ssa_name (SSA_NAME_VAR (info.target_inbound_names[i]), NULL);
+
+      info.target_outbound_names[i] = name;
+      assign = gimple_build_assign (name, info.default_values[i]);
+      SSA_NAME_DEF_STMT (name) = assign;
+      gsi_insert_before (gsi, assign, GSI_SAME_STMT);
+      update_stmt (assign);
+    }
+  return assign;
+}
+
+/* Deletes the unused bbs and edges that now contain the switch statement and
+   its empty branch bbs.  BBD is the now dead BB containing the original switch
+   statement, FINAL is the last BB of the converted switch statement (in terms
+   of succession).  */
+
+static void
+prune_bbs (basic_block bbd, basic_block final)
+{
+  edge_iterator ei;
+  edge e;
+
+  for (ei = ei_start (bbd->succs); (e = ei_safe_edge (ei)); )
+    {
+      basic_block bb;
+      bb = e->dest;
+      remove_edge (e);
+      if (bb != final)
+	delete_basic_block (bb);
+    }
+  delete_basic_block (bbd);
+}
+
+/* Add values to phi nodes in final_bb for the two new edges.  E1F is the edge
+   from the basic block loading values from an array and E2F from the basic
+   block loading default values.  BBF is the last switch basic block (see the
+   bbf description in the comment below).  */
+
+static void
+fix_phi_nodes (edge e1f, edge e2f, basic_block bbf)
+{
+  gimple_stmt_iterator gsi;
+  int i;
+
+  for (gsi = gsi_start_phis (bbf), i = 0;
+       !gsi_end_p (gsi); gsi_next (&gsi), i++)
+    {
+      gimple phi = gsi_stmt (gsi);
+      add_phi_arg (phi, info.target_inbound_names[i], e1f, UNKNOWN_LOCATION);
+      add_phi_arg (phi, info.target_outbound_names[i], e2f, UNKNOWN_LOCATION);
+    }
+
+}
+
+/* Creates a check whether the switch expression value actually falls into the
+   range given by all the cases.  If it does not, the temporaries are loaded
+   with default values instead.  SWTCH is the switch statement being converted.
+
+   bb0 is the bb with the switch statement, however, we'll end it with a
+       condition instead.
+
+   bb1 is the bb to be used when the range check went ok.  It is derived from
+       the switch BB
+
+   bb2 is the bb taken when the expression evaluated outside of the range
+       covered by the created arrays.  It is populated by loads of default
+       values.
+
+   bbF is a fall through for both bb1 and bb2 and contains exactly what
+       originally followed the switch statement.
+
+   bbD contains the switch statement (in the end).  It is unreachable but we
+       still need to strip off its edges.
+*/
+
+static void
+gen_inbound_check (gimple swtch)
+{
+  tree label_decl1 = create_artificial_label (UNKNOWN_LOCATION);
+  tree label_decl2 = create_artificial_label (UNKNOWN_LOCATION);
+  tree label_decl3 = create_artificial_label (UNKNOWN_LOCATION);
+  gimple label1, label2, label3;
+  tree utype, tidx;
+  tree bound;
+
+  gimple cond_stmt;
+
+  gimple last_assign;
+  gimple_stmt_iterator gsi;
+  basic_block bb0, bb1, bb2, bbf, bbd;
+  edge e01, e02, e21, e1d, e1f, e2f;
+  location_t loc = gimple_location (swtch);
+
+  gcc_assert (info.default_values);
+  bb0 = gimple_bb (swtch);
+
+  tidx = gimple_assign_lhs (info.arr_ref_first);
+  utype = TREE_TYPE (tidx);
+
+  /* (end of) block 0 */
+  gsi = gsi_for_stmt (info.arr_ref_first);
+  gsi_next (&gsi);
+
+  bound = fold_convert_loc (loc, utype, info.range_size);
+  cond_stmt = gimple_build_cond (LE_EXPR, tidx, bound, NULL_TREE, NULL_TREE);
+  gsi_insert_before (&gsi, cond_stmt, GSI_SAME_STMT);
+  update_stmt (cond_stmt);
+
+  /* block 2 */
+  label2 = gimple_build_label (label_decl2);
+  gsi_insert_before (&gsi, label2, GSI_SAME_STMT);
+  last_assign = gen_def_assigns (&gsi);
+
+  /* block 1 */
+  label1 = gimple_build_label (label_decl1);
+  gsi_insert_before (&gsi, label1, GSI_SAME_STMT);
+
+  /* block F */
+  gsi = gsi_start_bb (info.final_bb);
+  label3 = gimple_build_label (label_decl3);
+  gsi_insert_before (&gsi, label3, GSI_SAME_STMT);
+
+  /* cfg fix */
+  e02 = split_block (bb0, cond_stmt);
+  bb2 = e02->dest;
+
+  e21 = split_block (bb2, last_assign);
+  bb1 = e21->dest;
+  remove_edge (e21);
+
+  e1d = split_block (bb1, info.arr_ref_last);
+  bbd = e1d->dest;
+  remove_edge (e1d);
+
+  /* flags and profiles of the edge for in-range values */
+  e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE);
+  e01->probability = REG_BR_PROB_BASE - info.default_prob;
+  e01->count = info.other_count;
+
+  /* flags and profiles of the edge taking care of out-of-range values */
+  e02->flags &= ~EDGE_FALLTHRU;
+  e02->flags |= EDGE_FALSE_VALUE;
+  e02->probability = info.default_prob;
+  e02->count = info.default_count;
+
+  bbf = info.final_bb;
+
+  e1f = make_edge (bb1, bbf, EDGE_FALLTHRU);
+  e1f->probability = REG_BR_PROB_BASE;
+  e1f->count = info.other_count;
+
+  e2f = make_edge (bb2, bbf, EDGE_FALLTHRU);
+  e2f->probability = REG_BR_PROB_BASE;
+  e2f->count = info.default_count;
+
+  /* frequencies of the new BBs */
+  bb1->frequency = EDGE_FREQUENCY (e01);
+  bb2->frequency = EDGE_FREQUENCY (e02);
+  bbf->frequency = EDGE_FREQUENCY (e1f) + EDGE_FREQUENCY (e2f);
+
+  prune_bbs (bbd, info.final_bb); /* To keep calc_dfs_tree() in dominance.c
+				     happy.  */
+
+  fix_phi_nodes (e1f, e2f, bbf);
+
+  free_dominance_info (CDI_DOMINATORS);
+  free_dominance_info (CDI_POST_DOMINATORS);
+}
+
+/* The following function is invoked on every switch statement (the current one
+   is given in SWTCH) and runs the individual phases of switch conversion on it
+   one after another until one fails or the conversion is completed.  */
+
+static bool
+process_switch (gimple swtch)
+{
+  unsigned int i, branch_num = gimple_switch_num_labels (swtch);
+  tree index_type;
+
+  /* Operand 2 is either NULL_TREE or a vector of cases (stmt.c).  */
+  if (branch_num < 2)
+    {
+      info.reason = "switch has no labels\n";
+      return false;
+    }
+
+  info.final_bb = NULL;
+  info.switch_bb = gimple_bb (swtch);
+  info.index_expr = gimple_switch_index (swtch);
+  index_type = TREE_TYPE (info.index_expr);
+  info.arr_ref_first = NULL;
+  info.arr_ref_last = NULL;
+  info.default_prob = 0;
+  info.default_count = 0;
+  info.other_count = 0;
+  info.bit_test_uniq = 0;
+  info.bit_test_count = 0;
+  info.bit_test_bb[0] = NULL;
+  info.bit_test_bb[1] = NULL;
+
+  /* An ERROR_MARK occurs for various reasons including invalid data type.
+     (comment from stmt.c) */
+  if (index_type == error_mark_node)
+    {
+      info.reason = "index error.\n";
+      return false;
+    }
+
+  /* Check the case label values are within reasonable range:  */
+  if (!check_range (swtch))
+    return false;
+
+  /* For all the cases, see whether they are empty, the assignments they
+     represent constant and so on...  */
+  for (i = 0; i < branch_num; i++)
+    if (!check_process_case (gimple_switch_label (swtch, i)))
+      {
+	if (dump_file)
+	  fprintf (dump_file, "Processing of case %i failed\n", i);
+	return false;
+      }
+
+  if (info.bit_test_uniq <= 2)
+    {
+      rtl_profile_for_bb (gimple_bb (swtch));
+      if (expand_switch_using_bit_tests_p (gimple_switch_index (swtch),
+					   info.range_size, info.bit_test_uniq,
+					   info.bit_test_count))
+	{
+	  info.reason = "  Expanding as bit test is preferable\n";
+	  return false;
+	}
+    }
+
+  if (!check_final_bb ())
+    return false;
+
+  /* At this point all checks have passed and we can proceed with the
+     transformation.  */
+
+  create_temp_arrays ();
+  gather_default_values (gimple_switch_label (swtch, 0));
+  build_constructors (swtch);
+
+  build_arrays (swtch); /* Build the static arrays and assignments.   */
+  gen_inbound_check (swtch);	/* Build the bounds check.  */
+
+  /* Cleanup:  */
+  free_temp_arrays ();
+  return true;
+}
+
+/* The main function of the pass scans statements for switches and invokes
+   process_switch on them.  */
+
+static unsigned int
+do_switchconv (void)
+{
+  basic_block bb;
+
+  FOR_EACH_BB (bb)
+  {
+    gimple stmt = last_stmt (bb);
+    if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
+      {
+	if (dump_file)
+	  {
+	    expanded_location loc = expand_location (gimple_location (stmt));
+
+	    fprintf (dump_file, "beginning to process the following "
+		     "SWITCH statement (%s:%d) : ------- \n",
+		     loc.file, loc.line);
+	    print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+	    putc ('\n', dump_file);
+	  }
+
+	info.reason = NULL;
+	if (process_switch (stmt))
+	  {
+	    if (dump_file)
+	      {
+		fputs ("Switch converted\n", dump_file);
+		fputs ("--------------------------------\n", dump_file);
+	      }
+	  }
+	else
+	  {
+	    if (dump_file)
+	      {
+		gcc_assert (info.reason);
+		fputs ("Bailing out - ", dump_file);
+		fputs (info.reason, dump_file);
+		fputs ("--------------------------------\n", dump_file);
+	      }
+	  }
+      }
+  }
+
+  return 0;
+}
+
+/* The pass gate. */
+
+static bool
+switchconv_gate (void)
+{
+  return flag_tree_switch_conversion != 0;
+}
+
+struct gimple_opt_pass pass_convert_switch =
+{
+ {
+  GIMPLE_PASS,
+  "switchconv",				/* name */
+  switchconv_gate,			/* gate */
+  do_switchconv,			/* execute */
+  NULL,					/* sub */
+  NULL,					/* next */
+  0,					/* static_pass_number */
+  TV_TREE_SWITCH_CONVERSION,		/* tv_id */
+  PROP_cfg | PROP_ssa,	                /* properties_required */
+  0,					/* properties_provided */
+  0,					/* properties_destroyed */
+  0,					/* todo_flags_start */
+  TODO_update_ssa | TODO_dump_func
+  | TODO_ggc_collect | TODO_verify_ssa  /* todo_flags_finish */
+ }
+};