Patchwork Cleanup tree-switch-conversion a bit

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Submitter Steven Bosscher
Date April 17, 2012, 4:15 p.m.
Message ID <CABu31nPAfVnN-FVApXf_A6=HkWjaN7rQYznD548N+edxG530vg@mail.gmail.com>
Download mbox | patch
Permalink /patch/153245/
State New
Headers show

Comments

Steven Bosscher - April 17, 2012, 4:15 p.m.
> My goal for GCC 4.8 is to do just that: Move switch expansion to
> GIMPLE and add value profiling for switch expressions.

And the idea is to put all that code in tree-switch-conversion.c. But
there are a few clean-ups I wish to do on that code before that.
First, there is a global pass info structure that contains useful data
for all forms of GIMPLE_SWITCH lowering. I've "un-globalized" that
data with the attached patch. While there, I made the dump messages
uniform.

Bootstrapped and tested on powerpc-unknown-linux-gnu. OK?

Ciao!
Steven
* tree-switch-conversion.c (info): Remove global pass info.
	(check_range, check_process_case, check_final_bb, create_temp_arrays,
	free_temp_arrays, gather_default_values, build_constructors,
	array_value_type, build_one_array, build_arrays, gen_def_assigns,
	fix_phi_nodes, gen_inbound_check): Pass info around from ...
	(process_switch): ... here.  Unify message format.  Return a const
	char pointer to the failure reason message.
	(do_switchconv): Unify message format.  Update process_switch usage.
Richard Guenther - April 18, 2012, 9:05 a.m.
On Tue, Apr 17, 2012 at 6:15 PM, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
>> My goal for GCC 4.8 is to do just that: Move switch expansion to
>> GIMPLE and add value profiling for switch expressions.
>
> And the idea is to put all that code in tree-switch-conversion.c. But
> there are a few clean-ups I wish to do on that code before that.
> First, there is a global pass info structure that contains useful data
> for all forms of GIMPLE_SWITCH lowering. I've "un-globalized" that
> data with the attached patch. While there, I made the dump messages
> uniform.
>
> Bootstrapped and tested on powerpc-unknown-linux-gnu. OK?

Ok.

Thanks,
Richard.

> Ciao!
> Steven
H.J. Lu - April 19, 2012, 2:55 p.m.
On Tue, Apr 17, 2012 at 9:15 AM, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
>> My goal for GCC 4.8 is to do just that: Move switch expansion to
>> GIMPLE and add value profiling for switch expressions.
>
> And the idea is to put all that code in tree-switch-conversion.c. But
> there are a few clean-ups I wish to do on that code before that.
> First, there is a global pass info structure that contains useful data
> for all forms of GIMPLE_SWITCH lowering. I've "un-globalized" that
> data with the attached patch. While there, I made the dump messages
> uniform.
>
> Bootstrapped and tested on powerpc-unknown-linux-gnu. OK?
>

I think it caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53043

Patch

Index: tree-switch-conversion.c
===================================================================
--- tree-switch-conversion.c	(revision 186526)
+++ tree-switch-conversion.c	(working copy)
@@ -24,8 +24,8 @@  Software Foundation, 51 Franklin Street, Fifth Flo
      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
+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;
@@ -162,16 +162,12 @@  struct switch_conv_info
   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)
+check_range (gimple swtch, struct switch_conv_info *info)
 {
   tree min_case, max_case;
   unsigned int branch_num = gimple_switch_num_labels (swtch);
@@ -181,7 +177,7 @@  static bool
      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);
+  info->range_min = CASE_LOW (min_case);
 
   gcc_assert (branch_num > 1);
   gcc_assert (CASE_LOW (gimple_switch_label (swtch, 0)) == NULL_TREE);
@@ -191,22 +187,22 @@  static bool
   else
     range_max = CASE_LOW (max_case);
 
-  gcc_assert (info.range_min);
+  gcc_assert (info->range_min);
   gcc_assert (range_max);
 
-  info.range_size = int_const_binop (MINUS_EXPR, range_max, info.range_min);
+  info->range_size = int_const_binop (MINUS_EXPR, range_max, info->range_min);
 
-  gcc_assert (info.range_size);
-  if (!host_integerp (info.range_size, 1))
+  gcc_assert (info->range_size);
+  if (!host_integerp (info->range_size, 1))
     {
-      info.reason = "index range way too large or otherwise unusable.\n";
+      info->reason = "index range way too large or otherwise unusable";
       return false;
     }
 
-  if ((unsigned HOST_WIDE_INT) tree_low_cst (info.range_size, 1)
+  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";
+      info->reason = "the maximum range-branch ratio exceeded";
       return false;
     }
 
@@ -219,7 +215,7 @@  static bool
    and returns true.  Otherwise returns false.  */
 
 static bool
-check_process_case (tree cs)
+check_process_case (tree cs, struct switch_conv_info *info)
 {
   tree ldecl;
   basic_block label_bb, following_bb;
@@ -228,48 +224,48 @@  static bool
   ldecl = CASE_LABEL (cs);
   label_bb = label_to_block (ldecl);
 
-  e = find_edge (info.switch_bb, label_bb);
+  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;
+      info->default_prob = e->probability;
+      info->default_count = e->count;
     }
   else
     {
       int i;
-      info.other_count += e->count;
+      info->other_count += e->count;
       for (i = 0; i < 2; i++)
-	if (info.bit_test_bb[i] == label_bb)
+	if (info->bit_test_bb[i] == label_bb)
 	  break;
-	else if (info.bit_test_bb[i] == NULL)
+	else if (info->bit_test_bb[i] == NULL)
 	  {
-	    info.bit_test_bb[i] = label_bb;
-	    info.bit_test_uniq++;
+	    info->bit_test_bb[i] = label_bb;
+	    info->bit_test_uniq++;
 	    break;
 	  }
       if (i == 2)
-	info.bit_test_uniq = 3;
+	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;
+	info->bit_test_count += 2;
       else
-	info.bit_test_count++;
+	info->bit_test_count++;
     }
 
   if (!label_bb)
     {
-      info.reason = "  Bad case - cs BB  label is NULL\n";
+      info->reason = "bad case - cs BB  label is NULL";
       return false;
     }
 
   if (!single_pred_p (label_bb))
     {
-      if (info.final_bb && info.final_bb != label_bb)
+      if (info->final_bb && info->final_bb != label_bb)
 	{
-	  info.reason = "  Bad case - a non-final BB has two predecessors\n";
+	  info->reason = "bad case - a non-final BB has two predecessors";
 	  return false; /* sth complex going on in this branch  */
 	}
 
@@ -279,7 +275,7 @@  static bool
     {
       if (!empty_block_p (label_bb))
 	{
-	  info.reason = "  Bad case - a non-final BB not empty\n";
+	  info->reason = "bad case - a non-final BB not empty";
 	  return false;
 	}
 
@@ -287,11 +283,11 @@  static bool
       following_bb = single_succ (label_bb);
     }
 
-  if (!info.final_bb)
-    info.final_bb = following_bb;
-  else if (info.final_bb != following_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";
+      info->reason = "bad case - different final BB";
       return false; /* the only successor is not common for all the branches */
     }
 
@@ -304,31 +300,31 @@  static bool
    phi nodes are OK, otherwise false.  */
 
 static bool
-check_final_bb (void)
+check_final_bb (struct switch_conv_info *info)
 {
   gimple_stmt_iterator gsi;
 
-  info.phi_count = 0;
-  for (gsi = gsi_start_phis (info.final_bb); !gsi_end_p (gsi); gsi_next (&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++;
+      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))
+	  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";
+		  info->reason = "non-invariant value from a case";
 		  return false; /* Non-invariant argument.  */
 		}
 	      reloc = initializer_constant_valid_p (val, TREE_TYPE (val));
@@ -336,11 +332,11 @@  static bool
 		  || (!flag_pic && reloc == NULL_TREE))
 		{
 		  if (reloc)
-		    info.reason
-		      = "   Value from a case would need runtime relocations\n";
+		    info->reason
+		      = "value from a case would need runtime relocations";
 		  else
-		    info.reason
-		      = "   Value from a case is not a valid initializer\n";
+		    info->reason
+		      = "value from a case is not a valid initializer";
 		  return false;
 		}
 	    }
@@ -355,17 +351,17 @@  static bool
    vectors that will become constructors of new arrays.  */
 
 static void
-create_temp_arrays (void)
+create_temp_arrays (struct switch_conv_info *info)
 {
   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);
+  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
@@ -373,17 +369,17 @@  static void
    already become constructors and must be preserved.  */
 
 static void
-free_temp_arrays (void)
+free_temp_arrays (struct switch_conv_info *info)
 {
-  XDELETEVEC (info.constructors);
-  XDELETEVEC (info.default_values);
+  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)
+gather_default_values (tree default_case, struct switch_conv_info *info)
 {
   gimple_stmt_iterator gsi;
   basic_block bb = label_to_block (CASE_LABEL (default_case));
@@ -392,17 +388,17 @@  static void
 
   gcc_assert (CASE_LOW (default_case) == NULL_TREE);
 
-  if (bb == info.final_bb)
-    e = find_edge (info.switch_bb, bb);
+  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))
+  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;
+      info->default_values[i++] = val;
     }
 }
 
@@ -411,10 +407,10 @@  static void
    order of phi nodes.  SWTCH is the switch statement being converted.  */
 
 static void
-build_constructors (gimple swtch)
+build_constructors (gimple swtch, struct switch_conv_info *info)
 {
   unsigned i, branch_num = gimple_switch_num_labels (swtch);
-  tree pos = info.range_min;
+  tree pos = info->range_min;
 
   for (i = 1; i < branch_num; i++)
     {
@@ -425,8 +421,8 @@  static void
       gimple_stmt_iterator gsi;
       int j;
 
-      if (bb == info.final_bb)
-	e = find_edge (info.switch_bb, bb);
+      if (bb == info->final_bb)
+	e = find_edge (info->switch_bb, bb);
       else
 	e = single_succ_edge (bb);
       gcc_assert (e);
@@ -434,15 +430,15 @@  static void
       while (tree_int_cst_lt (pos, CASE_LOW (cs)))
 	{
 	  int k;
-	  for (k = 0; k < info.phi_count; k++)
+	  for (k = 0; k < info->phi_count; k++)
 	    {
 	      constructor_elt *elt;
 
 	      elt = VEC_quick_push (constructor_elt,
-				    info.constructors[k], NULL);
+				    info->constructors[k], NULL);
 	      elt->index = int_const_binop (MINUS_EXPR, pos,
-					    info.range_min);
-	      elt->value = info.default_values[k];
+					    info->range_min);
+	      elt->value = info->default_values[k];
 	    }
 
 	  pos = int_const_binop (PLUS_EXPR, pos, integer_one_node);
@@ -454,7 +450,7 @@  static void
 	high = CASE_HIGH (cs);
       else
 	high = CASE_LOW (cs);
-      for (gsi = gsi_start_phis (info.final_bb);
+      for (gsi = gsi_start_phis (info->final_bb);
 	   !gsi_end_p (gsi); gsi_next (&gsi))
 	{
 	  gimple phi = gsi_stmt (gsi);
@@ -467,8 +463,8 @@  static void
 	      constructor_elt *elt;
 
 	      elt = VEC_quick_push (constructor_elt,
-				    info.constructors[j], NULL);
-	      elt->index = int_const_binop (MINUS_EXPR, pos, info.range_min);
+				    info->constructors[j], NULL);
+	      elt->index = int_const_binop (MINUS_EXPR, pos, info->range_min);
 	      elt->value = val;
 
 	      pos = int_const_binop (PLUS_EXPR, pos, integer_one_node);
@@ -505,9 +501,10 @@  constructor_contains_same_values_p (VEC (construct
    all the constants.  */
 
 static tree
-array_value_type (gimple swtch, tree type, int num)
+array_value_type (gimple swtch, tree type, int num,
+		  struct switch_conv_info *info)
 {
-  unsigned int i, len = VEC_length (constructor_elt, info.constructors[num]);
+  unsigned int i, len = VEC_length (constructor_elt, info->constructors[num]);
   constructor_elt *elt;
   enum machine_mode mode;
   int sign = 0;
@@ -523,7 +520,7 @@  static tree
   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)
+  FOR_EACH_VEC_ELT (constructor_elt, info->constructors[num], i, elt)
     {
       double_int cst;
 
@@ -585,37 +582,37 @@  static tree
 
 static void
 build_one_array (gimple swtch, int num, tree arr_index_type, gimple phi,
-		 tree tidx)
+		 tree tidx, struct switch_conv_info *info)
 {
   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]);
+  gcc_assert (info->default_values[num]);
 
   name = make_ssa_name (SSA_NAME_VAR (PHI_RESULT (phi)), NULL);
-  info.target_inbound_names[num] = name;
+  info->target_inbound_names[num] = name;
 
-  cst = constructor_contains_same_values_p (info.constructors[num]);
+  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);
+      default_type = TREE_TYPE (info->default_values[num]);
+      value_type = array_value_type (swtch, default_type, num, info);
       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)
+	  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]);
+      ctor = build_constructor (array_type, info->constructors[num]);
       TREE_CONSTANT (ctor) = true;
       TREE_STATIC (ctor) = true;
 
@@ -645,7 +642,7 @@  build_one_array (gimple swtch, int num, tree arr_i
   SSA_NAME_DEF_STMT (name) = load;
   gsi_insert_before (&gsi, load, GSI_SAME_STMT);
   update_stmt (load);
-  info.arr_ref_last = load;
+  info->arr_ref_last = load;
 }
 
 /* Builds and initializes static arrays initialized with values gathered from
@@ -653,7 +650,7 @@  build_one_array (gimple swtch, int num, tree arr_i
    them.  */
 
 static void
-build_arrays (gimple swtch)
+build_arrays (gimple swtch, struct switch_conv_info *info)
 {
   tree arr_index_type;
   tree tidx, sub, tmp, utype;
@@ -665,19 +662,19 @@  static void
   gsi = gsi_for_stmt (swtch);
 
   /* Make sure we do not generate arithmetics in a subrange.  */
-  utype = TREE_TYPE (info.index_expr);
+  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);
+  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));
+			 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);
@@ -685,29 +682,29 @@  static void
 
   gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
   update_stmt (stmt);
-  info.arr_ref_first = stmt;
+  info->arr_ref_first = stmt;
 
-  for (gsi = gsi_start_phis (info.final_bb), i = 0;
+  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);
+    build_one_array (swtch, i, arr_index_type, gsi_stmt (gsi), tidx, info);
 }
 
 /* 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)
+gen_def_assigns (gimple_stmt_iterator *gsi, struct switch_conv_info *info)
 {
   int i;
   gimple assign = NULL;
 
-  for (i = 0; i < info.phi_count; i++)
+  for (i = 0; i < info->phi_count; i++)
     {
       tree name
-	= make_ssa_name (SSA_NAME_VAR (info.target_inbound_names[i]), NULL);
+	= 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]);
+      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);
@@ -743,7 +740,8 @@  prune_bbs (basic_block bbd, basic_block final)
    bbf description in the comment below).  */
 
 static void
-fix_phi_nodes (edge e1f, edge e2f, basic_block bbf)
+fix_phi_nodes (edge e1f, edge e2f, basic_block bbf,
+	       struct switch_conv_info *info)
 {
   gimple_stmt_iterator gsi;
   int i;
@@ -752,10 +750,9 @@  static void
        !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);
+      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
@@ -780,7 +777,7 @@  static void
 */
 
 static void
-gen_inbound_check (gimple swtch)
+gen_inbound_check (gimple swtch, struct switch_conv_info *info)
 {
   tree label_decl1 = create_artificial_label (UNKNOWN_LOCATION);
   tree label_decl2 = create_artificial_label (UNKNOWN_LOCATION);
@@ -797,17 +794,17 @@  static void
   edge e01, e02, e21, e1d, e1f, e2f;
   location_t loc = gimple_location (swtch);
 
-  gcc_assert (info.default_values);
+  gcc_assert (info->default_values);
   bb0 = gimple_bb (swtch);
 
-  tidx = gimple_assign_lhs (info.arr_ref_first);
+  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 = gsi_for_stmt (info->arr_ref_first);
   gsi_next (&gsi);
 
-  bound = fold_convert_loc (loc, utype, info.range_size);
+  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);
@@ -815,14 +812,14 @@  static void
   /* block 2 */
   label2 = gimple_build_label (label_decl2);
   gsi_insert_before (&gsi, label2, GSI_SAME_STMT);
-  last_assign = gen_def_assigns (&gsi);
+  last_assign = gen_def_assigns (&gsi, info);
 
   /* 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);
+  gsi = gsi_start_bb (info->final_bb);
   label3 = gimple_build_label (label_decl3);
   gsi_insert_before (&gsi, label3, GSI_SAME_STMT);
 
@@ -834,40 +831,40 @@  static void
   bb1 = e21->dest;
   remove_edge (e21);
 
-  e1d = split_block (bb1, info.arr_ref_last);
+  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;
+  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;
+  e02->probability = info->default_prob;
+  e02->count = info->default_count;
 
-  bbf = info.final_bb;
+  bbf = info->final_bb;
 
   e1f = make_edge (bb1, bbf, EDGE_FALLTHRU);
   e1f->probability = REG_BR_PROB_BASE;
-  e1f->count = info.other_count;
+  e1f->count = info->other_count;
 
   e2f = make_edge (bb2, bbf, EDGE_FALLTHRU);
   e2f->probability = REG_BR_PROB_BASE;
-  e2f->count = info.default_count;
+  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
+  prune_bbs (bbd, info->final_bb); /* To keep calc_dfs_tree() in dominance.c
 				     happy.  */
 
-  fix_phi_nodes (e1f, e2f, bbf);
+  fix_phi_nodes (e1f, e2f, bbf, info);
 
   free_dominance_info (CDI_DOMINATORS);
   free_dominance_info (CDI_POST_DOMINATORS);
@@ -875,25 +872,25 @@  static void
 
 /* 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.  */
+   one after another until one fails or the conversion is completed.
+   Returns NULL on success, or a pointer to a string with the reason why the
+   conversion failed.  */
 
-static bool
+static const char *
 process_switch (gimple swtch)
 {
   unsigned int i, branch_num = gimple_switch_num_labels (swtch);
   tree index_type;
+  struct switch_conv_info info;
 
   /* 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;
-    }
+    return "switch has no labels";
 
+  info.reason = NULL;
   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;
@@ -906,24 +903,26 @@  process_switch (gimple swtch)
 
   /* An ERROR_MARK occurs for various reasons including invalid data type.
      (comment from stmt.c) */
+  index_type = TREE_TYPE (info.index_expr);
   if (index_type == error_mark_node)
+    return "index error\n";
+
+  /* Check the case label values are within reasonable range:  */
+  if (!check_range (swtch, &info))
     {
-      info.reason = "index error.\n";
-      return false;
+      gcc_assert (info.reason);
+      return info.reason;
     }
 
-  /* 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 (!check_process_case (gimple_switch_label (swtch, i), &info))
       {
+	gcc_assert (info.reason);
 	if (dump_file)
-	  fprintf (dump_file, "Processing of case %i failed\n", i);
-	return false;
+	  fprintf (dump_file, "processing of case %i failed\n\t", i);
+	return info.reason;
       }
 
   if (info.bit_test_uniq <= 2)
@@ -933,27 +932,29 @@  process_switch (gimple swtch)
 					   info.range_size, info.bit_test_uniq,
 					   info.bit_test_count))
 	{
-	  info.reason = "  Expanding as bit test is preferable\n";
-	  return false;
+	  return "expanding as bit test is preferable";
 	}
     }
 
-  if (!check_final_bb ())
-    return false;
+  if (!check_final_bb (&info))
+    {
+      gcc_assert (info.reason);
+      return info.reason;
+    }
 
   /* 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);
+  create_temp_arrays (&info);
+  gather_default_values (gimple_switch_label (swtch, 0), &info);
+  build_constructors (swtch, &info);
 
-  build_arrays (swtch); /* Build the static arrays and assignments.   */
-  gen_inbound_check (swtch);	/* Build the bounds check.  */
+  build_arrays (swtch, &info); /* Build the static arrays and assignments.   */
+  gen_inbound_check (swtch, &info);	/* Build the bounds check.  */
 
   /* Cleanup:  */
-  free_temp_arrays ();
-  return true;
+  free_temp_arrays (&info);
+  return NULL;
 }
 
 /* The main function of the pass scans statements for switches and invokes
@@ -966,6 +967,7 @@  do_switchconv (void)
 
   FOR_EACH_BB (bb)
   {
+    const char *failure_reason;
     gimple stmt = last_stmt (bb);
     if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
       {
@@ -980,8 +982,8 @@  do_switchconv (void)
 	    putc ('\n', dump_file);
 	  }
 
-	info.reason = NULL;
-	if (process_switch (stmt))
+	failure_reason = process_switch (stmt);
+	if (! failure_reason)
 	  {
 	    if (dump_file)
 	      {
@@ -993,10 +995,9 @@  do_switchconv (void)
 	  {
 	    if (dump_file)
 	      {
-		gcc_assert (info.reason);
 		fputs ("Bailing out - ", dump_file);
-		fputs (info.reason, dump_file);
-		fputs ("--------------------------------\n", dump_file);
+		fputs (failure_reason, dump_file);
+		fputs ("\n--------------------------------\n", dump_file);
 	      }
 	  }
       }