Split tdesc_type into multiple classes

This patch makes tdesc_type an abstract base class and creates three
subclasses:

- tdesc_type_builtin, for builtin types
- tdesc_type_vector, for vector types
- tdesc_type_with_fields, for struct, union, flag and enum types

This allows getting rid of the union in tdesc_type and to not allow the
std::vector separately.  I tried to go further and create separate
classes for struct, union, flag and enum, but it proved too difficult.
One problem is that from the point of the of the target description
code, the types tdesc_type_* are opaque (only forward-declared).
Therefore, it doesn't know about inheritance relationship between those
classes.  This makes it impossible to make functions that accept a
pointer to a base class and pass a pointer to a derived class, for
example.  I think this patch here is a good compromise, and if somebody
wants to improve things further, the door is open.

A make_gdb_type virtual pure method is added to tdesc_type, which
replaces the current tdesc_gdb_type function.  Calling this method on a
tdesc_type returns the corresponding built gdb type.

gdb/ChangeLog:

	* target-descriptions.c (struct tdesc_type): Use default
	destructor.
	<u>: Remove.
	<accept>: Remove.
	(struct tdesc_type_builtin): New.
	(struct tdesc_type_vector): New.
	(struct tdesc_type_with_fields): New.
	(tdesc_predefined_types): Change type to tdesc_type_builtin[].
	(tdesc_gdb_type): Remove.
	(tdesc_register_type): Adjust.
	(tdesc_create_vector): Create tdesc_type_vector.
	(tdesc_create_struct): Create tdesc_type_with_fields.
	(tdesc_set_struct_size): Change parameter type.
	(tdesc_create_union): Create tdesc_type_with_fields.
	(tdesc_create_flags): Likewise.
	(tdesc_create_enum): Likewise.
	(tdesc_add_field): Change parameter type.
	(tdesc_add_typed_bitfield): Likewise.
	(tdesc_add_bitfield): Likewise.
	(tdesc_add_flag): Likewise.
	(tdesc_add_enum_value): Likewise.
	(print_c_tdesc) <visit>: Remove overload with tdesc_type
	parameter, add overloads for tdesc_type_builtin,
	tdesc_type_with_fields and tdesc_type_vector.
	<m_printed_type>: Remove.
	<m_printed_element_type, m_printed_type_with_fields>: Add.
	* target-descriptions.h (tdesc_create_enum): Change return type.
	(tdesc_add_typed_bitfield): Change parameter type.
	(tdesc_add_enum_value): Change parameter type.
	* xml-tdesc.c (struct tdesc_parsing_data) <current_type>: Change
	type to tdesc_type_with_fields.
	(tdesc_start_struct): Adjust.
	(tdesc_start_flags): Adjust.
	(tdesc_start_enum): Adjust.
	(tdesc_start_field): Adjust.
	* arch/tdesc.h (struct tdesc_type_builtin): Forward-declare.
	(struct tdesc_type_vector): Forward-declare.
	(struct tdesc_type_with_fields): Forward-declare.
	(tdesc_create_struct): Change return type.
	(tdesc_create_union): Likewise.
	(tdesc_create_flags): Likewise.
	(tdesc_add_field): Change parameter type.
	(tdesc_set_struct_size): Likewise.
	(tdesc_add_bitfield): Likewise.
	(tdesc_add_flag): Likewise.
	* features: Re-generate C files.

gdb/gdbserver/ChangeLog:

	* tdesc.c (struct tdesc_type): Change return type.
	(tdesc_add_flag): Change parameter type.
	(tdesc_add_bitfield): Likewise.
	(tdesc_add_field): Likewise.
	(tdesc_set_struct_size): Likewise.

1 files changed, 379 insertions, 348 deletions

diff --git a/gdb/target-descriptions.c b/gdb/target-descriptions.c
index 0f47fee16e..12d72fa128 100644
--- a/gdb/target-descriptions.c
+++ b/gdb/target-descriptions.c
@@ -49,7 +49,10 @@ public:
   virtual void visit_pre (const tdesc_feature *e) = 0;
   virtual void visit_post (const tdesc_feature *e) = 0;
 
-  virtual void visit (const tdesc_type *e) = 0;
+  virtual void visit (const tdesc_type_builtin *e) = 0;
+  virtual void visit (const tdesc_type_vector *e) = 0;
+  virtual void visit (const tdesc_type_with_fields *e) = 0;
+
   virtual void visit (const tdesc_reg *e) = 0;
 };
 
@@ -200,82 +203,313 @@ struct tdesc_type : tdesc_element
 {
   tdesc_type (const std::string &name_, enum tdesc_type_kind kind_)
     : name (name_), kind (kind_)
+  {}
+
+  virtual ~tdesc_type () = default;
+
+  DISABLE_COPY_AND_ASSIGN (tdesc_type);
+
+  /* The name of this type.   */
+  std::string name;
+
+  /* Identify the kind of this type.  */
+  enum tdesc_type_kind kind;
+
+  bool operator== (const tdesc_type &other) const
   {
-    memset (&u, 0, sizeof (u));
+    return name == other.name && kind == other.kind;
+  }
 
-    switch (kind)
-      {
-      case TDESC_TYPE_STRUCT:
-      case TDESC_TYPE_UNION:
-      case TDESC_TYPE_FLAGS:
-      case TDESC_TYPE_ENUM:
-	u.u.fields = new std::vector<tdesc_type_field> ();
-	break;
+  bool operator!= (const tdesc_type &other) const
+  {
+    return !(*this == other);
+  }
 
-      default:
-	break;
-      }
+  /* Construct, if necessary, and return the GDB type implementing this
+     target type for architecture GDBARCH.  */
+
+  virtual type *make_gdb_type (struct gdbarch *gdbarch) const = 0;
+};
+
+typedef std::unique_ptr<tdesc_type> tdesc_type_up;
+
+struct tdesc_type_builtin : tdesc_type
+{
+  tdesc_type_builtin (const std::string &name, enum tdesc_type_kind kind)
+  : tdesc_type (name, kind)
+  {}
+
+  void accept (tdesc_element_visitor &v) const override
+  {
+    v.visit (this);
   }
 
-  virtual ~tdesc_type ()
+  type *make_gdb_type (struct gdbarch *gdbarch) const override
   {
-    switch (kind)
+    switch (this->kind)
       {
-      case TDESC_TYPE_STRUCT:
-      case TDESC_TYPE_UNION:
-      case TDESC_TYPE_FLAGS:
-      case TDESC_TYPE_ENUM:
-	delete u.u.fields;
-	break;
+      /* Predefined types.  */
+      case TDESC_TYPE_BOOL:
+        return builtin_type (gdbarch)->builtin_bool;
 
-      default:
-	break;
+      case TDESC_TYPE_INT8:
+        return builtin_type (gdbarch)->builtin_int8;
+
+      case TDESC_TYPE_INT16:
+        return builtin_type (gdbarch)->builtin_int16;
+
+      case TDESC_TYPE_INT32:
+        return builtin_type (gdbarch)->builtin_int32;
+
+      case TDESC_TYPE_INT64:
+        return builtin_type (gdbarch)->builtin_int64;
+
+      case TDESC_TYPE_INT128:
+        return builtin_type (gdbarch)->builtin_int128;
+
+      case TDESC_TYPE_UINT8:
+        return builtin_type (gdbarch)->builtin_uint8;
+
+      case TDESC_TYPE_UINT16:
+        return builtin_type (gdbarch)->builtin_uint16;
+
+      case TDESC_TYPE_UINT32:
+        return builtin_type (gdbarch)->builtin_uint32;
+
+      case TDESC_TYPE_UINT64:
+        return builtin_type (gdbarch)->builtin_uint64;
+
+      case TDESC_TYPE_UINT128:
+        return builtin_type (gdbarch)->builtin_uint128;
+
+      case TDESC_TYPE_CODE_PTR:
+        return builtin_type (gdbarch)->builtin_func_ptr;
+
+      case TDESC_TYPE_DATA_PTR:
+        return builtin_type (gdbarch)->builtin_data_ptr;
+      }
+
+    type *gdb_type = tdesc_find_type (gdbarch, this->name.c_str ());
+    if (gdb_type != NULL)
+      return gdb_type;
+
+    switch (this->kind)
+      {
+      case TDESC_TYPE_IEEE_SINGLE:
+        return arch_float_type (gdbarch, -1, "builtin_type_ieee_single",
+				floatformats_ieee_single);
+
+      case TDESC_TYPE_IEEE_DOUBLE:
+        return arch_float_type (gdbarch, -1, "builtin_type_ieee_double",
+				floatformats_ieee_double);
+
+      case TDESC_TYPE_ARM_FPA_EXT:
+        return arch_float_type (gdbarch, -1, "builtin_type_arm_ext",
+				floatformats_arm_ext);
+
+      case TDESC_TYPE_I387_EXT:
+        return arch_float_type (gdbarch, -1, "builtin_type_i387_ext",
+				floatformats_i387_ext);
       }
+
+    internal_error (__FILE__, __LINE__,
+		    "Type \"%s\" has an unknown kind %d",
+		    this->name.c_str (), this->kind);
+
+    return NULL;
   }
+};
 
-  DISABLE_COPY_AND_ASSIGN (tdesc_type);
+/* tdesc_type for vector types.  */
 
-  /* The name of this type.   */
-  std::string name;
+struct tdesc_type_vector : tdesc_type
+{
+  tdesc_type_vector (const std::string &name, tdesc_type *element_type_, int count_)
+  : tdesc_type (name, TDESC_TYPE_VECTOR),
+    element_type (element_type_), count (count_)
+  {}
 
-  /* Identify the kind of this type.  */
-  enum tdesc_type_kind kind;
+  void accept (tdesc_element_visitor &v) const override
+  {
+    v.visit (this);
+  }
 
-  /* Kind-specific data.  */
-  union
+  type *make_gdb_type (struct gdbarch *gdbarch) const override
   {
-    /* Vector type.  */
-    struct
-    {
-      struct tdesc_type *type;
-      int count;
-    } v;
+    type *vector_gdb_type = tdesc_find_type (gdbarch, this->name.c_str ());
+    if (vector_gdb_type != NULL)
+      return vector_gdb_type;
 
-    /* Struct, union, flags, or enum type.  */
-    struct
-    {
-      std::vector<tdesc_type_field> *fields;
-      int size;
-    } u;
-  } u;
+    type *element_gdb_type = this->element_type->make_gdb_type (gdbarch);
+    vector_gdb_type = init_vector_type (element_gdb_type, this->count);
+    TYPE_NAME (vector_gdb_type) = xstrdup (this->name.c_str ());
+
+    return vector_gdb_type;
+  }
+
+  struct tdesc_type *element_type;
+  int count;
+};
+
+/* tdesc_type for struct, union, flags, and enum types.  */
+
+struct tdesc_type_with_fields : tdesc_type
+{
+  tdesc_type_with_fields (const std::string &name, tdesc_type_kind kind,
+			  int size_ = 0)
+  : tdesc_type (name, kind), size (size_)
+  {}
 
   void accept (tdesc_element_visitor &v) const override
   {
     v.visit (this);
   }
 
-  bool operator== (const tdesc_type &other) const
+  type *make_gdb_type_struct (struct gdbarch *gdbarch) const
   {
-    return name == other.name && kind == other.kind;
+    type *struct_gdb_type = arch_composite_type (gdbarch, NULL, TYPE_CODE_STRUCT);
+    TYPE_NAME (struct_gdb_type) = xstrdup (this->name.c_str ());
+    TYPE_TAG_NAME (struct_gdb_type) = TYPE_NAME (struct_gdb_type);
+
+    for (const tdesc_type_field &f : this->fields)
+      {
+	if (f.start != -1 && f.end != -1)
+	  {
+	    /* Bitfield.  */
+	    struct field *fld;
+	    struct type *field_gdb_type;
+	    int bitsize, total_size;
+
+	    /* This invariant should be preserved while creating types.  */
+	    gdb_assert (this->size != 0);
+	    if (f.type != NULL)
+	      field_gdb_type = f.type->make_gdb_type (gdbarch);
+	    else if (this->size > 4)
+	      field_gdb_type = builtin_type (gdbarch)->builtin_uint64;
+	    else
+	      field_gdb_type = builtin_type (gdbarch)->builtin_uint32;
+
+	    fld = append_composite_type_field_raw
+	      (struct_gdb_type, xstrdup (f.name.c_str ()), field_gdb_type);
+
+	    /* For little-endian, BITPOS counts from the LSB of
+	       the structure and marks the LSB of the field.  For
+	       big-endian, BITPOS counts from the MSB of the
+	       structure and marks the MSB of the field.  Either
+	       way, it is the number of bits to the "left" of the
+	       field.  To calculate this in big-endian, we need
+	       the total size of the structure.  */
+	    bitsize = f.end - f.start + 1;
+	    total_size = this->size * TARGET_CHAR_BIT;
+	    if (gdbarch_bits_big_endian (gdbarch))
+	      SET_FIELD_BITPOS (fld[0], total_size - f.start - bitsize);
+	    else
+	      SET_FIELD_BITPOS (fld[0], f.start);
+	    FIELD_BITSIZE (fld[0]) = bitsize;
+	  }
+	else
+	  {
+	    gdb_assert (f.start == -1 && f.end == -1);
+	    type *field_gdb_type = f.type->make_gdb_type (gdbarch);
+	    append_composite_type_field (struct_gdb_type,
+					 xstrdup (f.name.c_str ()),
+					 field_gdb_type);
+	  }
+      }
+
+    if (this->size != 0)
+      TYPE_LENGTH (struct_gdb_type) = this->size;
+
+    return struct_gdb_type;
   }
 
-  bool operator!= (const tdesc_type &other) const
+  type *make_gdb_type_union (struct gdbarch *gdbarch) const
   {
-    return !(*this == other);
+    type *union_gdb_type = arch_composite_type (gdbarch, NULL, TYPE_CODE_UNION);
+    TYPE_NAME (union_gdb_type) = xstrdup (this->name.c_str ());
+
+    for (const tdesc_type_field &f : this->fields)
+      {
+	type* field_gdb_type = f.type->make_gdb_type (gdbarch);
+	append_composite_type_field (union_gdb_type, xstrdup (f.name.c_str ()),
+				     field_gdb_type);
+
+	/* If any of the children of a union are vectors, flag the
+	   union as a vector also.  This allows e.g. a union of two
+	   vector types to show up automatically in "info vector".  */
+	if (TYPE_VECTOR (field_gdb_type))
+	  TYPE_VECTOR (union_gdb_type) = 1;
+      }
+
+    return union_gdb_type;
   }
-};
 
-typedef std::unique_ptr<tdesc_type> tdesc_type_up;
+  type *make_gdb_type_flags (struct gdbarch *gdbarch) const
+  {
+    type *flags_gdb_type = arch_flags_type (gdbarch, this->name.c_str (),
+					  this->size * TARGET_CHAR_BIT);
+
+    for (const tdesc_type_field &f : this->fields)
+      {
+      int bitsize = f.end - f.start + 1;
+
+      gdb_assert (f.type != NULL);
+      type *field_gdb_type = f.type->make_gdb_type (gdbarch);
+      append_flags_type_field (flags_gdb_type, f.start, bitsize,
+			       field_gdb_type, f.name.c_str ());
+      }
+
+    return flags_gdb_type;
+  }
+
+  type *make_gdb_type_enum (struct gdbarch *gdbarch) const
+  {
+    type *enum_gdb_type = arch_type (gdbarch, TYPE_CODE_ENUM,
+				   this->size * TARGET_CHAR_BIT,
+				   this->name.c_str ());
+
+    TYPE_UNSIGNED (enum_gdb_type) = 1;
+    for (const tdesc_type_field &f : this->fields)
+      {
+      struct field *fld
+	= append_composite_type_field_raw (enum_gdb_type,
+					   xstrdup (f.name.c_str ()),
+					   NULL);
+
+      SET_FIELD_BITPOS (fld[0], f.start);
+      }
+
+    return enum_gdb_type;
+  }
+
+  type *make_gdb_type (struct gdbarch *gdbarch) const override
+  {
+    type *gdb_type = tdesc_find_type (gdbarch, this->name.c_str ());
+    if (gdb_type != NULL)
+      return gdb_type;
+
+    switch (this->kind)
+    {
+      case TDESC_TYPE_STRUCT:
+	return make_gdb_type_struct (gdbarch);
+      case TDESC_TYPE_UNION:
+	return make_gdb_type_union (gdbarch);
+      case TDESC_TYPE_FLAGS:
+	return make_gdb_type_flags (gdbarch);
+      case TDESC_TYPE_ENUM:
+	return make_gdb_type_enum (gdbarch);
+    }
+
+    internal_error (__FILE__, __LINE__,
+		    "Type \"%s\" has an unknown kind %d",
+		    this->name.c_str (), this->kind);
+
+    return NULL;
+  }
+
+  std::vector<tdesc_type_field> fields;
+  int size;
+};
 
 /* A feature from a target description.  Each feature is a collection
    of other elements, e.g. registers and types.  */
@@ -725,7 +959,7 @@ tdesc_feature_name (const struct tdesc_feature *feature)
 }
 
 /* Predefined types.  */
-static struct tdesc_type tdesc_predefined_types[] =
+static tdesc_type_builtin tdesc_predefined_types[] =
 {
   { "bool", TDESC_TYPE_BOOL },
   { "int8", TDESC_TYPE_INT8 },
@@ -796,218 +1030,6 @@ tdesc_find_type (struct gdbarch *gdbarch, const char *id)
   return NULL;
 }
 
-/* Construct, if necessary, and return the GDB type implementing target
-   type TDESC_TYPE for architecture GDBARCH.  */
-
-static struct type *
-tdesc_gdb_type (struct gdbarch *gdbarch, struct tdesc_type *tdesc_type)
-{
-  struct type *type;
-
-  switch (tdesc_type->kind)
-    {
-    /* Predefined types.  */
-    case TDESC_TYPE_BOOL:
-      return builtin_type (gdbarch)->builtin_bool;
-
-    case TDESC_TYPE_INT8:
-      return builtin_type (gdbarch)->builtin_int8;
-
-    case TDESC_TYPE_INT16:
-      return builtin_type (gdbarch)->builtin_int16;
-
-    case TDESC_TYPE_INT32:
-      return builtin_type (gdbarch)->builtin_int32;
-
-    case TDESC_TYPE_INT64:
-      return builtin_type (gdbarch)->builtin_int64;
-
-    case TDESC_TYPE_INT128:
-      return builtin_type (gdbarch)->builtin_int128;
-
-    case TDESC_TYPE_UINT8:
-      return builtin_type (gdbarch)->builtin_uint8;
-
-    case TDESC_TYPE_UINT16:
-      return builtin_type (gdbarch)->builtin_uint16;
-
-    case TDESC_TYPE_UINT32:
-      return builtin_type (gdbarch)->builtin_uint32;
-
-    case TDESC_TYPE_UINT64:
-      return builtin_type (gdbarch)->builtin_uint64;
-
-    case TDESC_TYPE_UINT128:
-      return builtin_type (gdbarch)->builtin_uint128;
-
-    case TDESC_TYPE_CODE_PTR:
-      return builtin_type (gdbarch)->builtin_func_ptr;
-
-    case TDESC_TYPE_DATA_PTR:
-      return builtin_type (gdbarch)->builtin_data_ptr;
-
-    default:
-      break;
-    }
-
-  type = tdesc_find_type (gdbarch, tdesc_type->name.c_str ());
-  if (type)
-    return type;
-
-  switch (tdesc_type->kind)
-    {
-    case TDESC_TYPE_IEEE_SINGLE:
-      return arch_float_type (gdbarch, -1, "builtin_type_ieee_single",
-			      floatformats_ieee_single);
-
-    case TDESC_TYPE_IEEE_DOUBLE:
-      return arch_float_type (gdbarch, -1, "builtin_type_ieee_double",
-			      floatformats_ieee_double);
-
-    case TDESC_TYPE_ARM_FPA_EXT:
-      return arch_float_type (gdbarch, -1, "builtin_type_arm_ext",
-			      floatformats_arm_ext);
-
-    case TDESC_TYPE_I387_EXT:
-      return arch_float_type (gdbarch, -1, "builtin_type_i387_ext",
-			      floatformats_i387_ext);
-
-    /* Types defined by a target feature.  */
-    case TDESC_TYPE_VECTOR:
-      {
-	struct type *type, *field_type;
-
-	field_type = tdesc_gdb_type (gdbarch, tdesc_type->u.v.type);
-	type = init_vector_type (field_type, tdesc_type->u.v.count);
-	TYPE_NAME (type) = xstrdup (tdesc_type->name.c_str ());
-
-	return type;
-      }
-
-    case TDESC_TYPE_STRUCT:
-      {
-	struct type *type, *field_type;
-
-	type = arch_composite_type (gdbarch, NULL, TYPE_CODE_STRUCT);
-	TYPE_NAME (type) = xstrdup (tdesc_type->name.c_str ());
-	TYPE_TAG_NAME (type) = TYPE_NAME (type);
-
-	for (const tdesc_type_field &f : *tdesc_type->u.u.fields)
-	  {
-	    if (f.start != -1 && f.end != -1)
-	      {
-		/* Bitfield.  */
-		struct field *fld;
-		struct type *field_type;
-		int bitsize, total_size;
-
-		/* This invariant should be preserved while creating types.  */
-		gdb_assert (tdesc_type->u.u.size != 0);
-		if (f.type != NULL)
-		  field_type = tdesc_gdb_type (gdbarch, f.type);
-		else if (tdesc_type->u.u.size > 4)
-		  field_type = builtin_type (gdbarch)->builtin_uint64;
-		else
-		  field_type = builtin_type (gdbarch)->builtin_uint32;
-
-		fld = append_composite_type_field_raw
-		  (type, xstrdup (f.name.c_str ()), field_type);
-
-		/* For little-endian, BITPOS counts from the LSB of
-		   the structure and marks the LSB of the field.  For
-		   big-endian, BITPOS counts from the MSB of the
-		   structure and marks the MSB of the field.  Either
-		   way, it is the number of bits to the "left" of the
-		   field.  To calculate this in big-endian, we need
-		   the total size of the structure.  */
-		bitsize = f.end - f.start + 1;
-		total_size = tdesc_type->u.u.size * TARGET_CHAR_BIT;
-		if (gdbarch_bits_big_endian (gdbarch))
-		  SET_FIELD_BITPOS (fld[0], total_size - f.start - bitsize);
-		else
-		  SET_FIELD_BITPOS (fld[0], f.start);
-		FIELD_BITSIZE (fld[0]) = bitsize;
-	      }
-	    else
-	      {
-		gdb_assert (f.start == -1 && f.end == -1);
-		field_type = tdesc_gdb_type (gdbarch, f.type);
-		append_composite_type_field (type, xstrdup (f.name.c_str ()),
-					     field_type);
-	      }
-	  }
-
-	if (tdesc_type->u.u.size != 0)
-	  TYPE_LENGTH (type) = tdesc_type->u.u.size;
-	return type;
-      }
-
-    case TDESC_TYPE_UNION:
-      {
-	struct type *type, *field_type;
-
-	type = arch_composite_type (gdbarch, NULL, TYPE_CODE_UNION);
-	TYPE_NAME (type) = xstrdup (tdesc_type->name.c_str ());
-
-	for (const tdesc_type_field &f : *tdesc_type->u.u.fields)
-	  {
-	    field_type = tdesc_gdb_type (gdbarch, f.type);
-	    append_composite_type_field (type, xstrdup (f.name.c_str ()),
-					 field_type);
-
-	    /* If any of the children of a union are vectors, flag the
-	       union as a vector also.  This allows e.g. a union of two
-	       vector types to show up automatically in "info vector".  */
-	    if (TYPE_VECTOR (field_type))
-	      TYPE_VECTOR (type) = 1;
-	  }
-	return type;
-      }
-
-    case TDESC_TYPE_FLAGS:
-      {
-	type = arch_flags_type (gdbarch, tdesc_type->name.c_str (),
-				tdesc_type->u.u.size * TARGET_CHAR_BIT);
-	for (const tdesc_type_field &f : *tdesc_type->u.u.fields)
-	  {
-	    struct type *field_type;
-	    int bitsize = f.end - f.start + 1;
-
-	    gdb_assert (f.type != NULL);
-	    field_type = tdesc_gdb_type (gdbarch, f.type);
-	    append_flags_type_field (type, f.start, bitsize,
-				     field_type, f.name.c_str ());
-	  }
-
-	return type;
-      }
-
-    case TDESC_TYPE_ENUM:
-      {
-	type = arch_type (gdbarch, TYPE_CODE_ENUM,
-			  tdesc_type->u.u.size * TARGET_CHAR_BIT,
-			  tdesc_type->name.c_str ());
-	TYPE_UNSIGNED (type) = 1;
-	for (const tdesc_type_field &f : *tdesc_type->u.u.fields)
-	  {
-	    struct field *fld
-	      = append_composite_type_field_raw (type,
-						 xstrdup (f.name.c_str ()),
-						 NULL);
-
-	    SET_FIELD_BITPOS (fld[0], f.start);
-	  }
-
-	return type;
-      }
-    }
-
-  internal_error (__FILE__, __LINE__,
-		  "Type \"%s\" has an unknown kind %d",
-		  tdesc_type->name.c_str (), tdesc_type->kind);
-}
-
-
 /* Support for registers from target descriptions.  */
 
 /* Construct the per-gdbarch data.  */
@@ -1195,7 +1217,7 @@ tdesc_register_type (struct gdbarch *gdbarch, int regno)
     {
       /* First check for a predefined or target defined type.  */
       if (reg->tdesc_type)
-        arch_reg->type = tdesc_gdb_type (gdbarch, reg->tdesc_type);
+        arch_reg->type = reg->tdesc_type->make_gdb_type (gdbarch);
 
       /* Next try size-sensitive type shortcuts.  */
       else if (reg->type == "float")
@@ -1455,81 +1477,78 @@ struct tdesc_type *
 tdesc_create_vector (struct tdesc_feature *feature, const char *name,
 		     struct tdesc_type *field_type, int count)
 {
-  struct tdesc_type *type = new tdesc_type (name, TDESC_TYPE_VECTOR);
-
-  type->u.v.type = field_type;
-  type->u.v.count = count;
-
+  tdesc_type_vector *type = new tdesc_type_vector (name, field_type, count);
   feature->types.emplace_back (type);
+
   return type;
 }
 
 /* See arch/tdesc.h.  */
 
-struct tdesc_type *
+tdesc_type_with_fields *
 tdesc_create_struct (struct tdesc_feature *feature, const char *name)
 {
-  struct tdesc_type *type = new tdesc_type (name, TDESC_TYPE_STRUCT);
-
+  tdesc_type_with_fields *type
+    = new tdesc_type_with_fields (name, TDESC_TYPE_STRUCT);
   feature->types.emplace_back (type);
+
   return type;
 }
 
 /* See arch/tdesc.h.  */
 
 void
-tdesc_set_struct_size (struct tdesc_type *type, int size)
+tdesc_set_struct_size (tdesc_type_with_fields *type, int size)
 {
   gdb_assert (type->kind == TDESC_TYPE_STRUCT);
   gdb_assert (size > 0);
-  type->u.u.size = size;
+  type->size = size;
 }
 
 /* See arch/tdesc.h.  */
 
-struct tdesc_type *
+tdesc_type_with_fields *
 tdesc_create_union (struct tdesc_feature *feature, const char *name)
 {
-  struct tdesc_type *type = new tdesc_type (name, TDESC_TYPE_UNION);
-
+  tdesc_type_with_fields *type
+    = new tdesc_type_with_fields (name, TDESC_TYPE_UNION);
   feature->types.emplace_back (type);
+
   return type;
 }
 
 /* See arch/tdesc.h.  */
 
-struct tdesc_type *
+tdesc_type_with_fields *
 tdesc_create_flags (struct tdesc_feature *feature, const char *name,
 		    int size)
 {
-  struct tdesc_type *type = new tdesc_type (name, TDESC_TYPE_FLAGS);
-
   gdb_assert (size > 0);
 
-  type->u.u.size = size;
-
+  tdesc_type_with_fields *type
+    = new tdesc_type_with_fields (name, TDESC_TYPE_FLAGS, size);
   feature->types.emplace_back (type);
+
   return type;
 }
 
-struct tdesc_type *
+tdesc_type_with_fields *
 tdesc_create_enum (struct tdesc_feature *feature, const char *name,
 		   int size)
 {
-  struct tdesc_type *type = new tdesc_type (name, TDESC_TYPE_ENUM);
-
   gdb_assert (size > 0);
 
-  type->u.u.size = size;
-
+  tdesc_type_with_fields *type
+    = new tdesc_type_with_fields (name, TDESC_TYPE_ENUM, size);
   feature->types.emplace_back (type);
+
   return type;
 }
 
 /* See arch/tdesc.h.  */
 
 void
-tdesc_add_field (struct tdesc_type *type, const char *field_name,
+tdesc_add_field (tdesc_type_with_fields *type, const char *field_name,
 		 struct tdesc_type *field_type)
 {
   gdb_assert (type->kind == TDESC_TYPE_UNION
@@ -1537,31 +1556,31 @@ tdesc_add_field (struct tdesc_type *type, const char *field_name,
 
   /* Initialize start and end so we know this is not a bit-field
      when we print-c-tdesc.  */
-  type->u.u.fields->emplace_back (field_name, field_type, -1, -1);
+  type->fields.emplace_back (field_name, field_type, -1, -1);
 }
 
 void
-tdesc_add_typed_bitfield (struct tdesc_type *type, const char *field_name,
+tdesc_add_typed_bitfield (tdesc_type_with_fields *type, const char *field_name,
 			  int start, int end, struct tdesc_type *field_type)
 {
   gdb_assert (type->kind == TDESC_TYPE_STRUCT
 	      || type->kind == TDESC_TYPE_FLAGS);
   gdb_assert (start >= 0 && end >= start);
 
-  type->u.u.fields->emplace_back (field_name, field_type, start, end);
+  type->fields.emplace_back (field_name, field_type, start, end);
 }
 
 /* See arch/tdesc.h.  */
 
 void
-tdesc_add_bitfield (struct tdesc_type *type, const char *field_name,
+tdesc_add_bitfield (tdesc_type_with_fields *type, const char *field_name,
 		    int start, int end)
 {
   struct tdesc_type *field_type;
 
   gdb_assert (start >= 0 && end >= start);
 
-  if (type->u.u.size > 4)
+  if (type->size > 4)
     field_type = tdesc_predefined_type (TDESC_TYPE_UINT64);
   else
     field_type = tdesc_predefined_type (TDESC_TYPE_UINT32);
@@ -1572,26 +1591,25 @@ tdesc_add_bitfield (struct tdesc_type *type, const char *field_name,
 /* See arch/tdesc.h.  */
 
 void
-tdesc_add_flag (struct tdesc_type *type, int start,
+tdesc_add_flag (tdesc_type_with_fields *type, int start,
 		const char *flag_name)
 {
   gdb_assert (type->kind == TDESC_TYPE_FLAGS
 	      || type->kind == TDESC_TYPE_STRUCT);
 
-  type->u.u.fields->emplace_back (flag_name,
-				   tdesc_predefined_type (TDESC_TYPE_BOOL),
-				   start, start);
+  type->fields.emplace_back (flag_name,
+			     tdesc_predefined_type (TDESC_TYPE_BOOL),
+			     start, start);
 }
 
 void
-tdesc_add_enum_value (struct tdesc_type *type, int value,
+tdesc_add_enum_value (tdesc_type_with_fields *type, int value,
 		      const char *name)
 {
   gdb_assert (type->kind == TDESC_TYPE_ENUM);
-
-  type->u.u.fields->emplace_back (name,
-				   tdesc_predefined_type (TDESC_TYPE_INT32),
-				   value, -1);
+  type->fields.emplace_back (name,
+			     tdesc_predefined_type (TDESC_TYPE_INT32),
+			     value, -1);
 }
 
 /* See arch/tdesc.h.  */
@@ -1845,57 +1863,64 @@ public:
     printf_unfiltered ("}\n");
   }
 
-  void visit (const tdesc_type *type) override
+  void visit (const tdesc_type_builtin *type) override
+  {
+    error (_("C output is not supported type \"%s\"."), type->name.c_str ());
+  }
+
+  void visit (const tdesc_type_vector *type) override
   {
-    /* Now we do some "filtering" in order to know which variables to
-       declare.  This is needed because otherwise we would declare unused
-       variables `field_type' and `type'.  */
-    if (!m_printed_field_type)
+    if (!m_printed_element_type)
       {
-	printf_unfiltered ("  struct tdesc_type *field_type;\n");
-	m_printed_field_type = true;
+	printf_unfiltered ("  tdesc_type *element_type;\n");
+	m_printed_element_type = true;
       }
 
-    if ((type->kind == TDESC_TYPE_UNION
-	 || type->kind == TDESC_TYPE_STRUCT
-	 || type->kind == TDESC_TYPE_FLAGS
-	 || type->kind == TDESC_TYPE_ENUM)
-	&& !type->u.u.fields->empty ()
-	&& !m_printed_type)
+    printf_unfiltered
+      ("  element_type = tdesc_named_type (feature, \"%s\");\n",
+       type->element_type->name.c_str ());
+    printf_unfiltered
+      ("  tdesc_create_vector (feature, \"%s\", element_type, %d);\n",
+       type->name.c_str (), type->count);
+
+    printf_unfiltered ("\n");
+  }
+
+  void visit (const tdesc_type_with_fields *type) override
+  {
+    if (!m_printed_type_with_fields)
       {
-	printf_unfiltered ("  struct tdesc_type *type;\n");
-	m_printed_type = true;
+	printf_unfiltered ("  tdesc_type_with_fields *type_with_fields;\n");
+	m_printed_type_with_fields = true;
+      }
+
+    if (!type->fields.empty ()
+	&& !m_printed_field_type)
+      {
+	printf_unfiltered ("  tdesc_type *field_type;\n");
+	m_printed_field_type = true;
       }
 
     switch (type->kind)
       {
-      case TDESC_TYPE_VECTOR:
-	printf_unfiltered
-	  ("  field_type = tdesc_named_type (feature, \"%s\");\n",
-	   type->u.v.type->name.c_str ());
-	printf_unfiltered
-	  ("  tdesc_create_vector (feature, \"%s\", field_type, %d);\n",
-	   type->name.c_str (), type->u.v.count);
-	break;
       case TDESC_TYPE_STRUCT:
       case TDESC_TYPE_FLAGS:
 	if (type->kind == TDESC_TYPE_STRUCT)
 	  {
 	    printf_unfiltered
-	      ("  type = tdesc_create_struct (feature, \"%s\");\n",
+	      ("  type_with_fields = tdesc_create_struct (feature, \"%s\");\n",
 	       type->name.c_str ());
-	    if (type->u.u.size != 0)
+	    if (type->size != 0)
 	      printf_unfiltered
-		("  tdesc_set_struct_size (type, %d);\n",
-		 type->u.u.size);
+		("  tdesc_set_struct_size (type_with_fields, %d);\n", type->size);
 	  }
 	else
 	  {
 	    printf_unfiltered
-	      ("  type = tdesc_create_flags (feature, \"%s\", %d);\n",
-	       type->name.c_str (), type->u.u.size);
+	      ("  type_with_fields = tdesc_create_flags (feature, \"%s\", %d);\n",
+	       type->name.c_str (), type->size);
 	  }
-	for (const tdesc_type_field &f : *type->u.u.fields)
+	for (const tdesc_type_field &f : type->fields)
 	  {
 	    const char *type_name;
 
@@ -1911,26 +1936,24 @@ public:
 		  {
 		    gdb_assert (f.start == f.end);
 		    printf_unfiltered
-		      ("  tdesc_add_flag (type, %d, \"%s\");\n",
+		      ("  tdesc_add_flag (type_with_fields, %d, \"%s\");\n",
 		       f.start, f.name.c_str ());
 		  }
-		else if ((type->u.u.size == 4
-			  && f.type->kind == TDESC_TYPE_UINT32)
-			 || (type->u.u.size == 8
+		else if ((type->size == 4 && f.type->kind == TDESC_TYPE_UINT32)
+			 || (type->size == 8
 			     && f.type->kind == TDESC_TYPE_UINT64))
 		  {
 		    printf_unfiltered
-		      ("  tdesc_add_bitfield (type, \"%s\", %d, %d);\n",
+		      ("  tdesc_add_bitfield (type_with_fields, \"%s\", %d, %d);\n",
 		       f.name.c_str (), f.start, f.end);
 		  }
 		else
 		  {
 		    printf_unfiltered
-		      ("  field_type = tdesc_named_type (feature,"
-		       " \"%s\");\n",
+		      ("  field_type = tdesc_named_type (feature, \"%s\");\n",
 		       type_name);
 		    printf_unfiltered
-		      ("  tdesc_add_typed_bitfield (type, \"%s\","
+		      ("  tdesc_add_typed_bitfield (type_with_fields, \"%s\","
 		       " %d, %d, field_type);\n",
 		       f.name.c_str (), f.start, f.end);
 		  }
@@ -1944,37 +1967,38 @@ public:
 		   " \"%s\");\n",
 		   type_name);
 		printf_unfiltered
-		  ("  tdesc_add_field (type, \"%s\", field_type);\n",
+		  ("  tdesc_add_field (type_with_fields, \"%s\", field_type);\n",
 		   f.name.c_str ());
 	      }
 	  }
 	break;
       case TDESC_TYPE_UNION:
 	printf_unfiltered
-	  ("  type = tdesc_create_union (feature, \"%s\");\n",
+	  ("  type_with_fields = tdesc_create_union (feature, \"%s\");\n",
 	   type->name.c_str ());
-	for (const tdesc_type_field &f : *type->u.u.fields)
+	for (const tdesc_type_field &f : type->fields)
 	  {
 	    printf_unfiltered
 	      ("  field_type = tdesc_named_type (feature, \"%s\");\n",
 	       f.type->name.c_str ());
 	    printf_unfiltered
-	      ("  tdesc_add_field (type, \"%s\", field_type);\n",
+	      ("  tdesc_add_field (type_with_fields, \"%s\", field_type);\n",
 	       f.name.c_str ());
 	  }
 	break;
       case TDESC_TYPE_ENUM:
 	printf_unfiltered
-	  ("  type = tdesc_create_enum (feature, \"%s\", %d);\n",
-	   type->name.c_str (), type->u.u.size);
-	for (const tdesc_type_field &f : *type->u.u.fields)
+	  ("  type_with_fields = tdesc_create_enum (feature, \"%s\", %d);\n",
+	   type->name.c_str (), type->size);
+	for (const tdesc_type_field &f : type->fields)
 	  printf_unfiltered
-	    ("  tdesc_add_enum_value (type, %d, \"%s\");\n",
+	    ("  tdesc_add_enum_value (type_with_fields, %d, \"%s\");\n",
 	     f.start, f.name.c_str ());
 	break;
       default:
 	error (_("C output is not supported type \"%s\"."), type->name.c_str ());
       }
+
     printf_unfiltered ("\n");
   }
 
@@ -1995,8 +2019,15 @@ protected:
 
 private:
   char *m_function;
+
+  /* Did we print "struct tdesc_type *element_type;" yet?  */
+  bool m_printed_element_type = false;
+
+  /* Did we print "struct tdesc_type_with_fields *element_type;" yet?  */
+  bool m_printed_type_with_fields = false;
+
+  /* Did we print "struct tdesc_type *field_type;" yet?  */
   bool m_printed_field_type = false;
-  bool m_printed_type = false;
 };
 
 /* Print target description feature in C.  */