OSDN Git Service

Delete incorrect representations of avx2 shifts.
[pf3gnuchains/gcc-fork.git] / gcc / go / go-gcc.cc
index 46c149c..dbdf95f 100644 (file)
@@ -32,6 +32,7 @@ extern "C"
 #include "tree.h"
 #include "tree-iterator.h"
 #include "gimple.h"
+#include "toplev.h"
 
 #ifndef ENABLE_BUILD_WITH_CXX
 }
@@ -52,7 +53,7 @@ class Gcc_tree
   { }
 
   tree
-  get_tree()
+  get_tree() const
   { return this->t_; }
 
  private:
@@ -129,58 +130,75 @@ class Gcc_backend : public Backend
 
   Btype*
   error_type()
-  { gcc_unreachable(); }
+  { return this->make_type(error_mark_node); }
 
   Btype*
   void_type()
-  { gcc_unreachable(); }
+  { return this->make_type(void_type_node); }
 
   Btype*
   bool_type()
-  { gcc_unreachable(); }
+  { return this->make_type(boolean_type_node); }
 
   Btype*
-  integer_type(bool /* is_unsigned */, int /* bits */)
-  { gcc_unreachable(); }
+  integer_type(bool, int);
 
   Btype*
-  float_type(int /* bits */)
-  { gcc_unreachable(); }
+  float_type(int);
 
   Btype*
-  string_type()
-  { gcc_unreachable(); }
+  complex_type(int);
 
   Btype*
-  function_type(const Function_type*, Btype* /* receiver */,
-               const Btypes* /* parameters */,
-               const Btypes* /* results */)
-  { gcc_unreachable(); }
+  pointer_type(Btype*);
 
   Btype*
-  struct_type(const Struct_type*, const Btypes* /* field_types */)
-  { gcc_unreachable(); }
+  function_type(const Btyped_identifier&,
+               const std::vector<Btyped_identifier>&,
+               const std::vector<Btyped_identifier>&,
+               source_location);
 
   Btype*
-  array_type(const Btype* /* element_type */, const Bexpression* /* length */)
-  { gcc_unreachable(); }
+  struct_type(const std::vector<Btyped_identifier>&);
 
   Btype*
-  slice_type(const Btype* /* element_type */)
-  { gcc_unreachable(); }
+  array_type(Btype*, Bexpression*);
 
   Btype*
-  map_type(const Btype* /* key_type */, const Btype* /* value_type */,
-          source_location)
-  { gcc_unreachable(); }
+  placeholder_pointer_type(const std::string&, source_location, bool);
+
+  bool
+  set_placeholder_pointer_type(Btype*, Btype*);
+
+  bool
+  set_placeholder_function_type(Btype*, Btype*);
+
+  Btype*
+  placeholder_struct_type(const std::string&, source_location);
+
+  bool
+  set_placeholder_struct_type(Btype* placeholder,
+                             const std::vector<Btyped_identifier>&);
+
+  Btype*
+  placeholder_array_type(const std::string&, source_location);
+
+  bool
+  set_placeholder_array_type(Btype*, Btype*, Bexpression*);
 
   Btype*
-  channel_type(const Btype* /* element_type */)
-  { gcc_unreachable(); }
+  named_type(const std::string&, Btype*, source_location);
 
   Btype*
-  interface_type(const Interface_type*, const Btypes* /* method_types */)
-  { gcc_unreachable(); }
+  circular_pointer_type(Btype*, bool);
+
+  bool
+  is_circular_pointer_type(Btype*);
+
+  // Expressions.
+
+  Bexpression*
+  zero_expression(Btype*);
 
   // Statements.
 
@@ -248,13 +266,27 @@ class Gcc_backend : public Backend
   global_variable_set_init(Bvariable*, Bexpression*);
 
   Bvariable*
-  local_variable(Bfunction*, const std::string& name, Btype* type,
+  local_variable(Bfunction*, const std::string&, Btype*, bool,
                 source_location);
 
   Bvariable*
-  parameter_variable(Bfunction*, const std::string& name, Btype* type,
+  parameter_variable(Bfunction*, const std::string&, Btype*, bool,
                     source_location);
 
+  Bvariable*
+  temporary_variable(Bfunction*, Bblock*, Btype*, Bexpression*, bool,
+                    source_location, Bstatement**);
+
+  Bvariable*
+  immutable_struct(const std::string&, bool, Btype*, source_location);
+
+  void
+  immutable_struct_set_init(Bvariable*, const std::string&, bool, Btype*,
+                           source_location, Bexpression*);
+
+  Bvariable*
+  immutable_struct_reference(const std::string&, Btype*, source_location);
+
   // Labels.
 
   Blabel*
@@ -279,6 +311,17 @@ class Gcc_backend : public Backend
   Bstatement*
   make_statement(tree t)
   { return new Bstatement(t); }
+
+  // Make a Btype from a tree.
+  Btype*
+  make_type(tree t)
+  { return new Btype(t); }
+
+  Btype*
+  fill_in_struct(Btype*, const std::vector<Btyped_identifier>&);
+
+  Btype*
+  fill_in_array(Btype*, Btype*, Bexpression*);
 };
 
 // A helper function.
@@ -289,6 +332,404 @@ get_identifier_from_string(const std::string& str)
   return get_identifier_with_length(str.data(), str.length());
 }
 
+// Get an unnamed integer type.
+
+Btype*
+Gcc_backend::integer_type(bool is_unsigned, int bits)
+{
+  tree type;
+  if (is_unsigned)
+    {
+      if (bits == INT_TYPE_SIZE)
+        type = unsigned_type_node;
+      else if (bits == CHAR_TYPE_SIZE)
+        type = unsigned_char_type_node;
+      else if (bits == SHORT_TYPE_SIZE)
+        type = short_unsigned_type_node;
+      else if (bits == LONG_TYPE_SIZE)
+        type = long_unsigned_type_node;
+      else if (bits == LONG_LONG_TYPE_SIZE)
+        type = long_long_unsigned_type_node;
+      else
+        type = make_unsigned_type(bits);
+    }
+  else
+    {
+      if (bits == INT_TYPE_SIZE)
+        type = integer_type_node;
+      else if (bits == CHAR_TYPE_SIZE)
+        type = signed_char_type_node;
+      else if (bits == SHORT_TYPE_SIZE)
+        type = short_integer_type_node;
+      else if (bits == LONG_TYPE_SIZE)
+        type = long_integer_type_node;
+      else if (bits == LONG_LONG_TYPE_SIZE)
+        type = long_long_integer_type_node;
+      else
+        type = make_signed_type(bits);
+    }
+  return this->make_type(type);
+}
+
+// Get an unnamed float type.
+
+Btype*
+Gcc_backend::float_type(int bits)
+{
+  tree type;
+  if (bits == FLOAT_TYPE_SIZE)
+    type = float_type_node;
+  else if (bits == DOUBLE_TYPE_SIZE)
+    type = double_type_node;
+  else if (bits == LONG_DOUBLE_TYPE_SIZE)
+    type = long_double_type_node;
+  else
+    {
+      type = make_node(REAL_TYPE);
+      TYPE_PRECISION(type) = bits;
+      layout_type(type);
+    }
+  return this->make_type(type);
+}
+
+// Get an unnamed complex type.
+
+Btype*
+Gcc_backend::complex_type(int bits)
+{
+  tree type;
+  if (bits == FLOAT_TYPE_SIZE * 2)
+    type = complex_float_type_node;
+  else if (bits == DOUBLE_TYPE_SIZE * 2)
+    type = complex_double_type_node;
+  else if (bits == LONG_DOUBLE_TYPE_SIZE * 2)
+    type = complex_long_double_type_node;
+  else
+    {
+      type = make_node(REAL_TYPE);
+      TYPE_PRECISION(type) = bits / 2;
+      layout_type(type);
+      type = build_complex_type(type);
+    }
+  return this->make_type(type);
+}
+
+// Get a pointer type.
+
+Btype*
+Gcc_backend::pointer_type(Btype* to_type)
+{
+  tree to_type_tree = to_type->get_tree();
+  if (to_type_tree == error_mark_node)
+    return this->error_type();
+  tree type = build_pointer_type(to_type_tree);
+  return this->make_type(type);
+}
+
+// Make a function type.
+
+Btype*
+Gcc_backend::function_type(const Btyped_identifier& receiver,
+                          const std::vector<Btyped_identifier>& parameters,
+                          const std::vector<Btyped_identifier>& results,
+                          source_location location)
+{
+  tree args = NULL_TREE;
+  tree* pp = &args;
+  if (receiver.btype != NULL)
+    {
+      tree t = receiver.btype->get_tree();
+      if (t == error_mark_node)
+       return this->error_type();
+      *pp = tree_cons(NULL_TREE, t, NULL_TREE);
+      pp = &TREE_CHAIN(*pp);
+    }
+
+  for (std::vector<Btyped_identifier>::const_iterator p = parameters.begin();
+       p != parameters.end();
+       ++p)
+    {
+      tree t = p->btype->get_tree();
+      if (t == error_mark_node)
+       return this->error_type();
+      *pp = tree_cons(NULL_TREE, t, NULL_TREE);
+      pp = &TREE_CHAIN(*pp);
+    }
+
+  // Varargs is handled entirely at the Go level.  When converted to
+  // GENERIC functions are not varargs.
+  *pp = void_list_node;
+
+  tree result;
+  if (results.empty())
+    result = void_type_node;
+  else if (results.size() == 1)
+    result = results.front().btype->get_tree();
+  else
+    {
+      result = make_node(RECORD_TYPE);
+      tree field_trees = NULL_TREE;
+      pp = &field_trees;
+      for (std::vector<Btyped_identifier>::const_iterator p = results.begin();
+          p != results.end();
+          ++p)
+       {
+         const std::string name = (p->name.empty()
+                                   ? "UNNAMED"
+                                   : p->name);
+         tree name_tree = get_identifier_from_string(name);
+         tree field_type_tree = p->btype->get_tree();
+         if (field_type_tree == error_mark_node)
+           return this->error_type();
+         gcc_assert(TYPE_SIZE(field_type_tree) != NULL_TREE);
+         tree field = build_decl(location, FIELD_DECL, name_tree,
+                                 field_type_tree);
+         DECL_CONTEXT(field) = result;
+         *pp = field;
+         pp = &DECL_CHAIN(field);
+       }
+      TYPE_FIELDS(result) = field_trees;
+      layout_type(result);
+    }
+  if (result == error_mark_node)
+    return this->error_type();
+
+  tree fntype = build_function_type(result, args);
+  if (fntype == error_mark_node)
+    return this->error_type();
+
+  return this->make_type(build_pointer_type(fntype));
+}
+
+// Make a struct type.
+
+Btype*
+Gcc_backend::struct_type(const std::vector<Btyped_identifier>& fields)
+{
+  return this->fill_in_struct(this->make_type(make_node(RECORD_TYPE)), fields);
+}
+
+// Fill in the fields of a struct type.
+
+Btype*
+Gcc_backend::fill_in_struct(Btype* fill,
+                           const std::vector<Btyped_identifier>& fields)
+{
+  tree fill_tree = fill->get_tree();
+  tree field_trees = NULL_TREE;
+  tree* pp = &field_trees;
+  for (std::vector<Btyped_identifier>::const_iterator p = fields.begin();
+       p != fields.end();
+       ++p)
+    {
+      tree name_tree = get_identifier_from_string(p->name);
+      tree type_tree = p->btype->get_tree();
+      if (type_tree == error_mark_node)
+       return this->error_type();
+      tree field = build_decl(p->location, FIELD_DECL, name_tree, type_tree);
+      DECL_CONTEXT(field) = fill_tree;
+      *pp = field;
+      pp = &DECL_CHAIN(field);
+    }
+  TYPE_FIELDS(fill_tree) = field_trees;
+  layout_type(fill_tree);
+  return fill;
+}
+
+// Make an array type.
+
+Btype*
+Gcc_backend::array_type(Btype* element_btype, Bexpression* length)
+{
+  return this->fill_in_array(this->make_type(make_node(ARRAY_TYPE)),
+                            element_btype, length);
+}
+
+// Fill in an array type.
+
+Btype*
+Gcc_backend::fill_in_array(Btype* fill, Btype* element_type,
+                          Bexpression* length)
+{
+  tree element_type_tree = element_type->get_tree();
+  tree length_tree = length->get_tree();
+  if (element_type_tree == error_mark_node || length_tree == error_mark_node)
+    return this->error_type();
+
+  gcc_assert(TYPE_SIZE(element_type_tree) != NULL_TREE);
+
+  length_tree = fold_convert(sizetype, length_tree);
+
+  // build_index_type takes the maximum index, which is one less than
+  // the length.
+  tree index_type_tree = build_index_type(fold_build2(MINUS_EXPR, sizetype,
+                                                     length_tree,
+                                                     size_one_node));
+
+  tree fill_tree = fill->get_tree();
+  TREE_TYPE(fill_tree) = element_type_tree;
+  TYPE_DOMAIN(fill_tree) = index_type_tree;
+  TYPE_ADDR_SPACE(fill_tree) = TYPE_ADDR_SPACE(element_type_tree);
+  layout_type(fill_tree);
+
+  if (TYPE_STRUCTURAL_EQUALITY_P(element_type_tree))
+    SET_TYPE_STRUCTURAL_EQUALITY(fill_tree);
+  else if (TYPE_CANONICAL(element_type_tree) != element_type_tree
+          || TYPE_CANONICAL(index_type_tree) != index_type_tree)
+    TYPE_CANONICAL(fill_tree) =
+      build_array_type(TYPE_CANONICAL(element_type_tree),
+                      TYPE_CANONICAL(index_type_tree));
+
+  return fill;
+}
+
+// Create a placeholder for a pointer type.
+
+Btype*
+Gcc_backend::placeholder_pointer_type(const std::string& name,
+                                     source_location location, bool)
+{
+  tree ret = build_variant_type_copy(ptr_type_node);
+  if (!name.empty())
+    {
+      tree decl = build_decl(location, TYPE_DECL,
+                            get_identifier_from_string(name),
+                            ret);
+      TYPE_NAME(ret) = decl;
+    }
+  return this->make_type(ret);
+}
+
+// Set the real target type for a placeholder pointer type.
+
+bool
+Gcc_backend::set_placeholder_pointer_type(Btype* placeholder,
+                                         Btype* to_type)
+{
+  tree pt = placeholder->get_tree();
+  if (pt == error_mark_node)
+    return false;
+  gcc_assert(TREE_CODE(pt) == POINTER_TYPE);
+  tree tt = to_type->get_tree();
+  if (tt == error_mark_node)
+    {
+      TREE_TYPE(pt) = tt;
+      return false;
+    }
+  gcc_assert(TREE_CODE(tt) == POINTER_TYPE);
+  TREE_TYPE(pt) = TREE_TYPE(tt);
+  return true;
+}
+
+// Set the real values for a placeholder function type.
+
+bool
+Gcc_backend::set_placeholder_function_type(Btype* placeholder, Btype* ft)
+{
+  return this->set_placeholder_pointer_type(placeholder, ft);
+}
+
+// Create a placeholder for a struct type.
+
+Btype*
+Gcc_backend::placeholder_struct_type(const std::string& name,
+                                    source_location location)
+{
+  tree ret = make_node(RECORD_TYPE);
+  tree decl = build_decl(location, TYPE_DECL,
+                        get_identifier_from_string(name),
+                        ret);
+  TYPE_NAME(ret) = decl;
+  return this->make_type(ret);
+}
+
+// Fill in the fields of a placeholder struct type.
+
+bool
+Gcc_backend::set_placeholder_struct_type(
+    Btype* placeholder,
+    const std::vector<Btyped_identifier>& fields)
+{
+  tree t = placeholder->get_tree();
+  gcc_assert(TREE_CODE(t) == RECORD_TYPE && TYPE_FIELDS(t) == NULL_TREE);
+  Btype* r = this->fill_in_struct(placeholder, fields);
+  return r->get_tree() != error_mark_node;
+}
+
+// Create a placeholder for an array type.
+
+Btype*
+Gcc_backend::placeholder_array_type(const std::string& name,
+                                   source_location location)
+{
+  tree ret = make_node(ARRAY_TYPE);
+  tree decl = build_decl(location, TYPE_DECL,
+                        get_identifier_from_string(name),
+                        ret);
+  TYPE_NAME(ret) = decl;
+  return this->make_type(ret);
+}
+
+// Fill in the fields of a placeholder array type.
+
+bool
+Gcc_backend::set_placeholder_array_type(Btype* placeholder,
+                                       Btype* element_btype,
+                                       Bexpression* length)
+{
+  tree t = placeholder->get_tree();
+  gcc_assert(TREE_CODE(t) == ARRAY_TYPE && TREE_TYPE(t) == NULL_TREE);
+  Btype* r = this->fill_in_array(placeholder, element_btype, length);
+  return r->get_tree() != error_mark_node;
+}
+
+// Return a named version of a type.
+
+Btype*
+Gcc_backend::named_type(const std::string& name, Btype* btype,
+                       source_location location)
+{
+  tree type = btype->get_tree();
+  if (type == error_mark_node)
+    return this->error_type();
+  type = build_variant_type_copy(type);
+  tree decl = build_decl(location, TYPE_DECL,
+                        get_identifier_from_string(name),
+                        type);
+  TYPE_NAME(type) = decl;
+  return this->make_type(type);
+}
+
+// Return a pointer type used as a marker for a circular type.
+
+Btype*
+Gcc_backend::circular_pointer_type(Btype*, bool)
+{
+  return this->make_type(ptr_type_node);
+}
+
+// Return whether we might be looking at a circular type.
+
+bool
+Gcc_backend::is_circular_pointer_type(Btype* btype)
+{
+  return btype->get_tree() == ptr_type_node;
+}
+
+// Return the zero value for a type.
+
+Bexpression*
+Gcc_backend::zero_expression(Btype* btype)
+{
+  tree t = btype->get_tree();
+  tree ret;
+  if (t == error_mark_node)
+    ret = error_mark_node;
+  else
+    ret = build_zero_cst(t);
+  return tree_to_expr(ret);
+}
+
 // An expression as a statement.
 
 Bstatement*
@@ -428,8 +869,7 @@ Gcc_backend::switch_statement(
                                 ? EXPR_LOCATION((*ps)->get_tree())
                                 : UNKNOWN_LOCATION);
          tree label = create_artificial_label(loc);
-         tree c = build3_loc(loc, CASE_LABEL_EXPR, void_type_node, NULL_TREE,
-                             NULL_TREE, label);
+         tree c = build_case_label(NULL_TREE, NULL_TREE, label);
          append_to_statement_list(c, &stmt_list);
        }
       else
@@ -443,8 +883,7 @@ Gcc_backend::switch_statement(
                return this->error_statement();
              source_location loc = EXPR_LOCATION(t);
              tree label = create_artificial_label(loc);
-             tree c = build3_loc(loc, CASE_LABEL_EXPR, void_type_node,
-                                 (*pcv)->get_tree(), NULL_TREE, label);
+             tree c = build_case_label((*pcv)->get_tree(), NULL_TREE, label);
              append_to_statement_list(c, &stmt_list);
            }
        }
@@ -669,7 +1108,8 @@ Gcc_backend::global_variable_set_init(Bvariable* var, Bexpression* expr)
 
 Bvariable*
 Gcc_backend::local_variable(Bfunction* function, const std::string& name,
-                           Btype* btype, source_location location)
+                           Btype* btype, bool is_address_taken,
+                           source_location location)
 {
   tree type_tree = btype->get_tree();
   if (type_tree == error_mark_node)
@@ -679,6 +1119,8 @@ Gcc_backend::local_variable(Bfunction* function, const std::string& name,
                         type_tree);
   DECL_CONTEXT(decl) = function->get_tree();
   TREE_USED(decl) = 1;
+  if (is_address_taken)
+    TREE_ADDRESSABLE(decl) = 1;
   go_preserve_from_gc(decl);
   return new Bvariable(decl);
 }
@@ -687,7 +1129,8 @@ Gcc_backend::local_variable(Bfunction* function, const std::string& name,
 
 Bvariable*
 Gcc_backend::parameter_variable(Bfunction* function, const std::string& name,
-                               Btype* btype, source_location location)
+                               Btype* btype, bool is_address_taken,
+                               source_location location)
 {
   tree type_tree = btype->get_tree();
   if (type_tree == error_mark_node)
@@ -698,6 +1141,147 @@ Gcc_backend::parameter_variable(Bfunction* function, const std::string& name,
   DECL_CONTEXT(decl) = function->get_tree();
   DECL_ARG_TYPE(decl) = type_tree;
   TREE_USED(decl) = 1;
+  if (is_address_taken)
+    TREE_ADDRESSABLE(decl) = 1;
+  go_preserve_from_gc(decl);
+  return new Bvariable(decl);
+}
+
+// Make a temporary variable.
+
+Bvariable*
+Gcc_backend::temporary_variable(Bfunction* function, Bblock* bblock,
+                               Btype* btype, Bexpression* binit,
+                               bool is_address_taken,
+                               source_location location,
+                               Bstatement** pstatement)
+{
+  tree type_tree = btype->get_tree();
+  tree init_tree = binit == NULL ? NULL_TREE : binit->get_tree();
+  if (type_tree == error_mark_node || init_tree == error_mark_node)
+    {
+      *pstatement = this->error_statement();
+      return this->error_variable();
+    }
+
+  tree var;
+  // We can only use create_tmp_var if the type is not addressable.
+  if (!TREE_ADDRESSABLE(type_tree))
+    var = create_tmp_var(type_tree, "GOTMP");
+  else
+    {
+      gcc_assert(bblock != NULL);
+      var = build_decl(location, VAR_DECL,
+                      create_tmp_var_name("GOTMP"),
+                      type_tree);
+      DECL_ARTIFICIAL(var) = 1;
+      DECL_IGNORED_P(var) = 1;
+      TREE_USED(var) = 1;
+      // FIXME: Permitting function to be NULL here is a temporary
+      // measure until we have a proper representation of the init
+      // function.
+      if (function != NULL)
+       DECL_CONTEXT(var) = function->get_tree();
+      else
+       {
+         gcc_assert(current_function_decl != NULL_TREE);
+         DECL_CONTEXT(var) = current_function_decl;
+       }
+
+      // We have to add this variable to the BLOCK and the BIND_EXPR.
+      tree bind_tree = bblock->get_tree();
+      gcc_assert(TREE_CODE(bind_tree) == BIND_EXPR);
+      tree block_tree = BIND_EXPR_BLOCK(bind_tree);
+      gcc_assert(TREE_CODE(block_tree) == BLOCK);
+      DECL_CHAIN(var) = BLOCK_VARS(block_tree);
+      BLOCK_VARS(block_tree) = var;
+      BIND_EXPR_VARS(bind_tree) = BLOCK_VARS(block_tree);
+    }
+
+  if (init_tree != NULL_TREE)
+    DECL_INITIAL(var) = fold_convert_loc(location, type_tree, init_tree);
+
+  if (is_address_taken)
+    TREE_ADDRESSABLE(var) = 1;
+
+  *pstatement = this->make_statement(build1_loc(location, DECL_EXPR,
+                                               void_type_node, var));
+  return new Bvariable(var);
+}
+
+// Create a named immutable initialized data structure.
+
+Bvariable*
+Gcc_backend::immutable_struct(const std::string& name, bool, Btype* btype,
+                             source_location location)
+{
+  tree type_tree = btype->get_tree();
+  if (type_tree == error_mark_node)
+    return this->error_variable();
+  gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
+  tree decl = build_decl(location, VAR_DECL,
+                        get_identifier_from_string(name),
+                        build_qualified_type(type_tree, TYPE_QUAL_CONST));
+  TREE_STATIC(decl) = 1;
+  TREE_READONLY(decl) = 1;
+  TREE_CONSTANT(decl) = 1;
+  TREE_USED(decl) = 1;
+  DECL_ARTIFICIAL(decl) = 1;
+
+  // We don't call rest_of_decl_compilation until we have the
+  // initializer.
+
+  go_preserve_from_gc(decl);
+  return new Bvariable(decl);
+}
+
+// Set the initializer for a variable created by immutable_struct.
+// This is where we finish compiling the variable.
+
+void
+Gcc_backend::immutable_struct_set_init(Bvariable* var, const std::string&,
+                                      bool is_common, Btype*,
+                                      source_location,
+                                      Bexpression* initializer)
+{
+  tree decl = var->get_tree();
+  tree init_tree = initializer->get_tree();
+  if (decl == error_mark_node || init_tree == error_mark_node)
+    return;
+
+  DECL_INITIAL(decl) = init_tree;
+
+  // We can't call make_decl_one_only until we set DECL_INITIAL.
+  if (!is_common)
+    TREE_PUBLIC(decl) = 1;
+  else
+    {
+      make_decl_one_only(decl, DECL_ASSEMBLER_NAME(decl));
+      resolve_unique_section(decl, 1, 0);
+    }
+
+  rest_of_decl_compilation(decl, 1, 0);
+}
+
+// Return a reference to an immutable initialized data structure
+// defined in another package.
+
+Bvariable*
+Gcc_backend::immutable_struct_reference(const std::string& name, Btype* btype,
+                                       source_location location)
+{
+  tree type_tree = btype->get_tree();
+  if (type_tree == error_mark_node)
+    return this->error_variable();
+  gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
+  tree decl = build_decl(location, VAR_DECL,
+                        get_identifier_from_string(name),
+                        build_qualified_type(type_tree, TYPE_QUAL_CONST));
+  TREE_READONLY(decl) = 1;
+  TREE_CONSTANT(decl) = 1;
+  DECL_ARTIFICIAL(decl) = 1;
+  TREE_PUBLIC(decl) = 1;
+  DECL_EXTERNAL(decl) = 1;
   go_preserve_from_gc(decl);
   return new Bvariable(decl);
 }
@@ -801,6 +1385,12 @@ tree_to_block(tree t)
 }
 
 tree
+type_to_tree(Btype* bt)
+{
+  return bt->get_tree();
+}
+
+tree
 expr_to_tree(Bexpression* be)
 {
   return be->get_tree();