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compiler: Rewrite handling of untyped numeric constants.
[pf3gnuchains/gcc-fork.git] / gcc / go / gofrontend / statements.cc
index eef9398..7f91e55 100644 (file)
@@ -8,23 +8,6 @@
 
 #include <gmp.h>
 
-#ifndef ENABLE_BUILD_WITH_CXX
-extern "C"
-{
-#endif
-
-#include "intl.h"
-#include "tree.h"
-#include "gimple.h"
-#include "convert.h"
-#include "tree-iterator.h"
-#include "tree-flow.h"
-#include "real.h"
-
-#ifndef ENABLE_BUILD_WITH_CXX
-}
-#endif
-
 #include "go-c.h"
 #include "types.h"
 #include "expressions.h"
@@ -32,11 +15,12 @@ extern "C"
 #include "runtime.h"
 #include "backend.h"
 #include "statements.h"
+#include "ast-dump.h"
 
 // Class Statement.
 
 Statement::Statement(Statement_classification classification,
-                    source_location location)
+                    Location location)
   : classification_(classification), location_(location)
 {
 }
@@ -148,27 +132,23 @@ Statement::thunk_statement()
   return ret;
 }
 
-// Get a tree for a Statement.  This is really done by the child
-// class.
+// Convert a Statement to the backend representation.  This is really
+// done by the child class.
 
-tree
-Statement::get_tree(Translate_context* context)
+Bstatement*
+Statement::get_backend(Translate_context* context)
 {
   if (this->classification_ == STATEMENT_ERROR)
-    return error_mark_node;
-
-  return this->do_get_tree(context);
+    return context->backend()->error_statement();
+  return this->do_get_backend(context);
 }
 
-// Build tree nodes and set locations.
+// Dump AST representation for a statement to a dump context.
 
-tree
-Statement::build_stmt_1(int tree_code_value, tree node)
+void
+Statement::dump_statement(Ast_dump_context* ast_dump_context) const
 {
-  tree ret = build1(static_cast<tree_code>(tree_code_value),
-                   void_type_node, node);
-  SET_EXPR_LOCATION(ret, this->location_);
-  return ret;
+  this->do_dump_statement(ast_dump_context);
 }
 
 // Note that this statement is erroneous.  This is called by children
@@ -195,7 +175,7 @@ Statement::report_error(const char* msg)
 class Error_statement : public Statement
 {
  public:
-  Error_statement(source_location location)
+  Error_statement(Location location)
     : Statement(STATEMENT_ERROR, location)
   { }
 
@@ -204,15 +184,27 @@ class Error_statement : public Statement
   do_traverse(Traverse*)
   { return TRAVERSE_CONTINUE; }
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 };
 
+// Dump the AST representation for an error statement.
+
+void
+Error_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "Error statement" << std::endl;
+}
+
 // Make an error statement.
 
 Statement*
-Statement::make_error_statement(source_location location)
+Statement::make_error_statement(Location location)
 {
   return new Error_statement(location);
 }
@@ -246,51 +238,91 @@ Variable_declaration_statement::do_traverse_assignments(
   return true;
 }
 
-// Return the tree for a variable declaration.
+// Lower the variable's initialization expression.
 
-tree
-Variable_declaration_statement::do_get_tree(Translate_context* context)
+Statement*
+Variable_declaration_statement::do_lower(Gogo* gogo, Named_object* function,
+                                        Block*, Statement_inserter* inserter)
+{
+  this->var_->var_value()->lower_init_expression(gogo, function, inserter);
+  return this;
+}
+
+// Convert a variable declaration to the backend representation.
+
+Bstatement*
+Variable_declaration_statement::do_get_backend(Translate_context* context)
 {
   Variable* var = this->var_->var_value();
   Bvariable* bvar = this->var_->get_backend_variable(context->gogo(),
                                                     context->function());
   tree init = var->get_init_tree(context->gogo(), context->function());
-  Bexpression* binit = init == NULL_TREE ? NULL : tree_to_expr(init);
-  Bstatement* ret;
+  Bexpression* binit = init == NULL ? NULL : tree_to_expr(init);
+
   if (!var->is_in_heap())
     {
-      gcc_assert(binit != NULL);
-      ret = context->backend()->init_statement(bvar, binit);
+      go_assert(binit != NULL);
+      return context->backend()->init_statement(bvar, binit);
     }
-  else
+
+  // Something takes the address of this variable, so the value is
+  // stored in the heap.  Initialize it to newly allocated memory
+  // space, and assign the initial value to the new space.
+  Location loc = this->location();
+  Named_object* newfn = context->gogo()->lookup_global("new");
+  go_assert(newfn != NULL && newfn->is_function_declaration());
+  Expression* func = Expression::make_func_reference(newfn, NULL, loc);
+  Expression_list* params = new Expression_list();
+  params->push_back(Expression::make_type(var->type(), loc));
+  Expression* call = Expression::make_call(func, params, false, loc);
+  context->gogo()->lower_expression(context->function(), NULL, &call);
+  Temporary_statement* temp = Statement::make_temporary(NULL, call, loc);
+  Bstatement* btemp = temp->get_backend(context);
+
+  Bstatement* set = NULL;
+  if (binit != NULL)
     {
-      // Something takes the address of this variable, so the value is
-      // stored in the heap.  Initialize it to newly allocated memory
-      // space, and assign the initial value to the new space.
-      source_location loc = this->location();
-      tree decl = var_to_tree(bvar);
-      tree decl_type = TREE_TYPE(decl);
-      gcc_assert(POINTER_TYPE_P(decl_type));
-      tree size = TYPE_SIZE_UNIT(TREE_TYPE(decl_type));
-      tree space = context->gogo()->allocate_memory(var->type(), size, loc);
-      if (binit != NULL)
-       space = save_expr(space);
-      space = fold_convert_loc(loc, decl_type, space);
-      Bstatement* s1 = context->backend()->init_statement(bvar,
-                                                         tree_to_expr(space));
-      if (binit == NULL)
-       ret = s1;
-      else
-       {
-         tree indir = build_fold_indirect_ref_loc(loc, space);
-         Bexpression* bindir = tree_to_expr(indir);
-         Bstatement* s2 = context->backend()->assignment_statement(bindir,
-                                                                   binit,
-                                                                   loc);
-         ret = context->backend()->compound_statement(s1, s2);
-       }
+      Expression* e = Expression::make_temporary_reference(temp, loc);
+      e = Expression::make_unary(OPERATOR_MULT, e, loc);
+      Bexpression* be = tree_to_expr(e->get_tree(context));
+      set = context->backend()->assignment_statement(be, binit, loc);
+    }
+
+  Expression* ref = Expression::make_temporary_reference(temp, loc);
+  Bexpression* bref = tree_to_expr(ref->get_tree(context));
+  Bstatement* sinit = context->backend()->init_statement(bvar, bref);
+
+  std::vector<Bstatement*> stats;
+  stats.reserve(3);
+  stats.push_back(btemp);
+  if (set != NULL)
+    stats.push_back(set);
+  stats.push_back(sinit);
+  return context->backend()->statement_list(stats);
+}
+
+// Dump the AST representation for a variable declaration.
+
+void
+Variable_declaration_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+
+  go_assert(var_->is_variable());
+  ast_dump_context->ostream() << "var " << this->var_->name() <<  " ";
+  Variable* var = this->var_->var_value();
+  if (var->has_type())
+    {
+      ast_dump_context->dump_type(var->type());
+      ast_dump_context->ostream() << " ";
     }
-  return stat_to_tree(ret);
+  if (var->init() != NULL)
+    {
+      ast_dump_context->ostream() <<  "= ";
+      ast_dump_context->dump_expression(var->init());
+    }
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make a variable declaration.
@@ -358,7 +390,7 @@ Temporary_statement::do_determine_types()
   if (this->type_ == NULL)
     {
       this->type_ = this->init_->type();
-      gcc_assert(!this->type_->is_abstract());
+      go_assert(!this->type_->is_abstract());
     }
 }
 
@@ -370,7 +402,13 @@ Temporary_statement::do_check_types(Gogo*)
   if (this->type_ != NULL && this->init_ != NULL)
     {
       std::string reason;
-      if (!Type::are_assignable(this->type_, this->init_->type(), &reason))
+      bool ok;
+      if (this->are_hidden_fields_ok_)
+       ok = Type::are_assignable_hidden_ok(this->type_, this->init_->type(),
+                                           &reason);
+      else
+       ok = Type::are_assignable(this->type_, this->init_->type(), &reason);
+      if (!ok)
        {
          if (reason.empty())
            error_at(this->location(), "incompatible types in assignment");
@@ -382,12 +420,12 @@ Temporary_statement::do_check_types(Gogo*)
     }
 }
 
-// Return a tree.
+// Convert to backend representation.
 
-tree
-Temporary_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Temporary_statement::do_get_backend(Translate_context* context)
 {
-  gcc_assert(this->bvariable_ == NULL);
+  go_assert(this->bvariable_ == NULL);
 
   // FIXME: Permitting FUNCTION to be NULL here is a temporary measure
   // until we have a better representation of the init function.
@@ -398,7 +436,7 @@ Temporary_statement::do_get_tree(Translate_context* context)
   else
     bfunction = tree_to_function(function->func_value()->get_decl());
 
-  Btype* btype = tree_to_type(this->type()->get_tree(context->gogo()));
+  Btype* btype = this->type()->get_backend(context->gogo());
 
   Bexpression* binit;
   if (this->init_ == NULL)
@@ -409,7 +447,7 @@ Temporary_statement::do_get_tree(Translate_context* context)
     {
       Expression* init = Expression::make_cast(this->type_, this->init_,
                                               this->location());
-      context->gogo()->lower_expression(context->function(), &init);
+      context->gogo()->lower_expression(context->function(), NULL, &init);
       binit = tree_to_expr(init->get_tree(context));
     }
 
@@ -419,7 +457,7 @@ Temporary_statement::do_get_tree(Translate_context* context)
                                           btype, binit,
                                           this->is_address_taken_,
                                           this->location(), &statement);
-  return stat_to_tree(statement);
+  return statement;
 }
 
 // Return the backend variable.
@@ -429,17 +467,37 @@ Temporary_statement::get_backend_variable(Translate_context* context) const
 {
   if (this->bvariable_ == NULL)
     {
-      gcc_assert(saw_errors());
+      go_assert(saw_errors());
       return context->backend()->error_variable();
     }
   return this->bvariable_;
 }
 
+// Dump the AST represemtation for a temporary statement
+
+void
+Temporary_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_temp_variable_name(this);
+  if (this->type_ != NULL)
+    {
+      ast_dump_context->ostream() << " ";
+      ast_dump_context->dump_type(this->type_);
+    }
+  if (this->init_ != NULL)
+    {
+      ast_dump_context->ostream() << " = ";
+      ast_dump_context->dump_expression(this->init_);
+    }
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make and initialize a temporary variable in BLOCK.
 
 Temporary_statement*
 Statement::make_temporary(Type* type, Expression* init,
-                         source_location location)
+                         Location location)
 {
   return new Temporary_statement(type, init, location);
 }
@@ -450,11 +508,17 @@ class Assignment_statement : public Statement
 {
  public:
   Assignment_statement(Expression* lhs, Expression* rhs,
-                      source_location location)
+                      Location location)
     : Statement(STATEMENT_ASSIGNMENT, location),
-      lhs_(lhs), rhs_(rhs)
+      lhs_(lhs), rhs_(rhs), are_hidden_fields_ok_(false)
   { }
 
+  // Note that it is OK for this assignment statement to set hidden
+  // fields.
+  void
+  set_hidden_fields_are_ok()
+  { this->are_hidden_fields_ok_ = true; }
+
  protected:
   int
   do_traverse(Traverse* traverse);
@@ -468,14 +532,20 @@ class Assignment_statement : public Statement
   void
   do_check_types(Gogo*);
 
-  tree
-  do_get_tree(Translate_context*);
+  Bstatement*
+  do_get_backend(Translate_context*);
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // Left hand side--the lvalue.
   Expression* lhs_;
   // Right hand side--the rvalue.
   Expression* rhs_;
+  // True if this statement may set hidden fields in the assignment
+  // statement.  This is used for generated method stubs.
+  bool are_hidden_fields_ok_;
 };
 
 // Traversal.
@@ -524,7 +594,12 @@ Assignment_statement::do_check_types(Gogo*)
   Type* lhs_type = this->lhs_->type();
   Type* rhs_type = this->rhs_->type();
   std::string reason;
-  if (!Type::are_assignable(lhs_type, rhs_type, &reason))
+  bool ok;
+  if (this->are_hidden_fields_ok_)
+    ok = Type::are_assignable_hidden_ok(lhs_type, rhs_type, &reason);
+  else
+    ok = Type::are_assignable(lhs_type, rhs_type, &reason);
+  if (!ok)
     {
       if (reason.empty())
        error_at(this->location(), "incompatible types in assignment");
@@ -538,43 +613,86 @@ Assignment_statement::do_check_types(Gogo*)
     this->set_is_error();
 }
 
-// Build a tree for an assignment statement.
+// Convert an assignment statement to the backend representation.
 
-tree
-Assignment_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Assignment_statement::do_get_backend(Translate_context* context)
 {
   tree rhs_tree = this->rhs_->get_tree(context);
-
   if (this->lhs_->is_sink_expression())
-    return rhs_tree;
-
+    return context->backend()->expression_statement(tree_to_expr(rhs_tree));
   tree lhs_tree = this->lhs_->get_tree(context);
-
-  if (lhs_tree == error_mark_node || rhs_tree == error_mark_node)
-    return error_mark_node;
-
   rhs_tree = Expression::convert_for_assignment(context, this->lhs_->type(),
                                                this->rhs_->type(), rhs_tree,
                                                this->location());
-  if (rhs_tree == error_mark_node)
-    return error_mark_node;
+  return context->backend()->assignment_statement(tree_to_expr(lhs_tree),
+                                                 tree_to_expr(rhs_tree),
+                                                 this->location());
+}
 
-  Bstatement* ret;
-  ret = context->backend()->assignment_statement(tree_to_expr(lhs_tree),
-                                                tree_to_expr(rhs_tree),
-                                                this->location());
-  return stat_to_tree(ret);
+// Dump the AST representation for an assignment statement.
+
+void
+Assignment_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
+    const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(this->lhs_);
+  ast_dump_context->ostream() << " = " ;
+  ast_dump_context->dump_expression(this->rhs_);
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make an assignment statement.
 
 Statement*
 Statement::make_assignment(Expression* lhs, Expression* rhs,
-                          source_location location)
+                          Location location)
 {
   return new Assignment_statement(lhs, rhs, location);
 }
 
+// The Move_subexpressions class is used to move all top-level
+// subexpressions of an expression.  This is used for things like
+// index expressions in which we must evaluate the index value before
+// it can be changed by a multiple assignment.
+
+class Move_subexpressions : public Traverse
+{
+ public:
+  Move_subexpressions(int skip, Block* block)
+    : Traverse(traverse_expressions),
+      skip_(skip), block_(block)
+  { }
+
+ protected:
+  int
+  expression(Expression**);
+
+ private:
+  // The number of subexpressions to skip moving.  This is used to
+  // avoid moving the array itself, as we only need to move the index.
+  int skip_;
+  // The block where new temporary variables should be added.
+  Block* block_;
+};
+
+int
+Move_subexpressions::expression(Expression** pexpr)
+{
+  if (this->skip_ > 0)
+    --this->skip_;
+  else if ((*pexpr)->temporary_reference_expression() == NULL)
+    {
+      Location loc = (*pexpr)->location();
+      Temporary_statement* temp = Statement::make_temporary(NULL, *pexpr, loc);
+      this->block_->add_statement(temp);
+      *pexpr = Expression::make_temporary_reference(temp, loc);
+    }
+  // We only need to move top-level subexpressions.
+  return TRAVERSE_SKIP_COMPONENTS;
+}
+
 // The Move_ordered_evals class is used to find any subexpressions of
 // an expression that have an evaluation order dependency.  It creates
 // temporary variables to hold them.
@@ -602,9 +720,18 @@ Move_ordered_evals::expression(Expression** pexpr)
   // We have to look at subexpressions first.
   if ((*pexpr)->traverse_subexpressions(this) == TRAVERSE_EXIT)
     return TRAVERSE_EXIT;
+
+  int i;
+  if ((*pexpr)->must_eval_subexpressions_in_order(&i))
+    {
+      Move_subexpressions ms(i, this->block_);
+      if ((*pexpr)->traverse_subexpressions(&ms) == TRAVERSE_EXIT)
+       return TRAVERSE_EXIT;
+    }
+
   if ((*pexpr)->must_eval_in_order())
     {
-      source_location loc = (*pexpr)->location();
+      Location loc = (*pexpr)->location();
       Temporary_statement* temp = Statement::make_temporary(NULL, *pexpr, loc);
       this->block_->add_statement(temp);
       *pexpr = Expression::make_temporary_reference(temp, loc);
@@ -618,7 +745,7 @@ class Assignment_operation_statement : public Statement
 {
  public:
   Assignment_operation_statement(Operator op, Expression* lhs, Expression* rhs,
-                                source_location location)
+                                Location location)
     : Statement(STATEMENT_ASSIGNMENT_OPERATION, location),
       op_(op), lhs_(lhs), rhs_(rhs)
   { }
@@ -629,14 +756,17 @@ class Assignment_operation_statement : public Statement
 
   bool
   do_traverse_assignments(Traverse_assignments*)
-  { gcc_unreachable(); }
+  { go_unreachable(); }
 
   Statement*
-  do_lower(Gogo*, Named_object*, Block*);
+  do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
+
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // The operator (OPERATOR_PLUSEQ, etc.).
@@ -662,9 +792,9 @@ Assignment_operation_statement::do_traverse(Traverse* traverse)
 
 Statement*
 Assignment_operation_statement::do_lower(Gogo*, Named_object*,
-                                        Block* enclosing)
+                                        Block* enclosing, Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   // We have to evaluate the left hand side expression only once.  We
   // do this by moving out any expression with side effects.
@@ -711,7 +841,7 @@ Assignment_operation_statement::do_lower(Gogo*, Named_object*,
       op = OPERATOR_BITCLEAR;
       break;
     default:
-      gcc_unreachable();
+      go_unreachable();
     }
 
   Expression* binop = Expression::make_binary(op, lval, this->rhs_, loc);
@@ -728,11 +858,24 @@ Assignment_operation_statement::do_lower(Gogo*, Named_object*,
     }
 }
 
+// Dump the AST representation for an assignment operation statement
+
+void
+Assignment_operation_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(this->lhs_);
+  ast_dump_context->dump_operator(this->op_);
+  ast_dump_context->dump_expression(this->rhs_);
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make an assignment operation statement.
 
 Statement*
 Statement::make_assignment_operation(Operator op, Expression* lhs,
-                                    Expression* rhs, source_location location)
+                                    Expression* rhs, Location location)
 {
   return new Assignment_operation_statement(op, lhs, rhs, location);
 }
@@ -745,31 +888,43 @@ class Tuple_assignment_statement : public Statement
 {
  public:
   Tuple_assignment_statement(Expression_list* lhs, Expression_list* rhs,
-                            source_location location)
+                            Location location)
     : Statement(STATEMENT_TUPLE_ASSIGNMENT, location),
-      lhs_(lhs), rhs_(rhs)
+      lhs_(lhs), rhs_(rhs), are_hidden_fields_ok_(false)
   { }
 
+  // Note that it is OK for this assignment statement to set hidden
+  // fields.
+  void
+  set_hidden_fields_are_ok()
+  { this->are_hidden_fields_ok_ = true; }
+
  protected:
   int
   do_traverse(Traverse* traverse);
 
   bool
   do_traverse_assignments(Traverse_assignments*)
-  { gcc_unreachable(); }
+  { go_unreachable(); }
 
   Statement*
-  do_lower(Gogo*, Named_object*, Block*);
+  do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // Left hand side--a list of lvalues.
   Expression_list* lhs_;
   // Right hand side--a list of rvalues.
   Expression_list* rhs_;
+  // True if this statement may set hidden fields in the assignment
+  // statement.  This is used for generated method stubs.
+  bool are_hidden_fields_ok_;
 };
 
 // Traversal.
@@ -786,19 +941,20 @@ Tuple_assignment_statement::do_traverse(Traverse* traverse)
 // up into a set of single assignments.
 
 Statement*
-Tuple_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
+Tuple_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
+                                    Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Block* b = new Block(enclosing, loc);
-  
+
   // First move out any subexpressions on the left hand side.  The
   // right hand side will be evaluated in the required order anyhow.
   Move_ordered_evals moe(b);
-  for (Expression_list::const_iterator plhs = this->lhs_->begin();
+  for (Expression_list::iterator plhs = this->lhs_->begin();
        plhs != this->lhs_->end();
        ++plhs)
-    (*plhs)->traverse_subexpressions(&moe);
+    Expression::traverse(&*plhs, &moe);
 
   std::vector<Temporary_statement*> temps;
   temps.reserve(this->lhs_->size());
@@ -808,7 +964,7 @@ Tuple_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
        plhs != this->lhs_->end();
        ++plhs, ++prhs)
     {
-      gcc_assert(prhs != this->rhs_->end());
+      go_assert(prhs != this->rhs_->end());
 
       if ((*plhs)->is_error_expression()
          || (*plhs)->type()->is_error()
@@ -818,17 +974,19 @@ Tuple_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
 
       if ((*plhs)->is_sink_expression())
        {
-         b->add_statement(Statement::make_statement(*prhs));
+         b->add_statement(Statement::make_statement(*prhs, true));
          continue;
        }
 
       Temporary_statement* temp = Statement::make_temporary((*plhs)->type(),
                                                            *prhs, loc);
+      if (this->are_hidden_fields_ok_)
+       temp->set_hidden_fields_are_ok();
       b->add_statement(temp);
       temps.push_back(temp);
 
     }
-  gcc_assert(prhs == this->rhs_->end());
+  go_assert(prhs == this->rhs_->end());
 
   prhs = this->rhs_->begin();
   std::vector<Temporary_statement*>::const_iterator ptemp = temps.begin();
@@ -847,19 +1005,37 @@ Tuple_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
 
       Expression* ref = Expression::make_temporary_reference(*ptemp, loc);
       Statement* s = Statement::make_assignment(*plhs, ref, loc);
+      if (this->are_hidden_fields_ok_)
+       {
+         Assignment_statement* as = static_cast<Assignment_statement*>(s);
+         as->set_hidden_fields_are_ok();
+       }
       b->add_statement(s);
       ++ptemp;
     }
-  gcc_assert(ptemp == temps.end());
+  go_assert(ptemp == temps.end() || saw_errors());
 
   return Statement::make_block_statement(b, loc);
 }
 
+// Dump the AST representation for a tuple assignment statement.
+
+void
+Tuple_assignment_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression_list(this->lhs_);
+  ast_dump_context->ostream() << " = ";
+  ast_dump_context->dump_expression_list(this->rhs_);
+  ast_dump_context->ostream()  << std::endl;
+}
+
 // Make a tuple assignment statement.
 
 Statement*
 Statement::make_tuple_assignment(Expression_list* lhs, Expression_list* rhs,
-                                source_location location)
+                                Location location)
 {
   return new Tuple_assignment_statement(lhs, rhs, location);
 }
@@ -872,7 +1048,7 @@ class Tuple_map_assignment_statement : public Statement
 public:
   Tuple_map_assignment_statement(Expression* val, Expression* present,
                                 Expression* map_index,
-                                source_location location)
+                                Location location)
     : Statement(STATEMENT_TUPLE_MAP_ASSIGNMENT, location),
       val_(val), present_(present), map_index_(map_index)
   { }
@@ -883,14 +1059,17 @@ public:
 
   bool
   do_traverse_assignments(Traverse_assignments*)
-  { gcc_unreachable(); }
+  { go_unreachable(); }
 
   Statement*
-  do_lower(Gogo*, Named_object*, Block*);
+  do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
+
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // Lvalue which receives the value from the map.
@@ -916,9 +1095,9 @@ Tuple_map_assignment_statement::do_traverse(Traverse* traverse)
 
 Statement*
 Tuple_map_assignment_statement::do_lower(Gogo*, Named_object*,
-                                        Block* enclosing)
+                                        Block* enclosing, Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Map_index_expression* map_index = this->map_index_->map_index_expression();
   if (map_index == NULL)
@@ -956,15 +1135,19 @@ Tuple_map_assignment_statement::do_lower(Gogo*, Named_object*,
     Statement::make_temporary(Type::lookup_bool_type(), NULL, loc);
   b->add_statement(present_temp);
 
-  // present_temp = mapaccess2(MAP, &key_temp, &val_temp)
-  Expression* ref = Expression::make_temporary_reference(key_temp, loc);
-  Expression* a1 = Expression::make_unary(OPERATOR_AND, ref, loc);
+  // present_temp = mapaccess2(DESCRIPTOR, MAP, &key_temp, &val_temp)
+  Expression* a1 = Expression::make_type_descriptor(map_type, loc);
+  Expression* a2 = map_index->map();
+  Temporary_reference_expression* ref =
+    Expression::make_temporary_reference(key_temp, loc);
+  Expression* a3 = Expression::make_unary(OPERATOR_AND, ref, loc);
   ref = Expression::make_temporary_reference(val_temp, loc);
-  Expression* a2 = Expression::make_unary(OPERATOR_AND, ref, loc);
-  Expression* call = Runtime::make_call(Runtime::MAPACCESS2, loc, 3,
-                                       map_index->map(), a1, a2);
+  Expression* a4 = Expression::make_unary(OPERATOR_AND, ref, loc);
+  Expression* call = Runtime::make_call(Runtime::MAPACCESS2, loc, 4,
+                                       a1, a2, a3, a4);
 
   ref = Expression::make_temporary_reference(present_temp, loc);
+  ref->set_is_lvalue();
   Statement* s = Statement::make_assignment(ref, call, loc);
   b->add_statement(s);
 
@@ -981,12 +1164,27 @@ Tuple_map_assignment_statement::do_lower(Gogo*, Named_object*,
   return Statement::make_block_statement(b, loc);
 }
 
+// Dump the AST representation for a tuple map assignment statement.
+
+void
+Tuple_map_assignment_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(this->val_);
+  ast_dump_context->ostream() << ", ";
+  ast_dump_context->dump_expression(this->present_);
+  ast_dump_context->ostream() << " = ";
+  ast_dump_context->dump_expression(this->map_index_);
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a map assignment statement which returns a pair of values.
 
 Statement*
 Statement::make_tuple_map_assignment(Expression* val, Expression* present,
                                     Expression* map_index,
-                                    source_location location)
+                                    Location location)
 {
   return new Tuple_map_assignment_statement(val, present, map_index, location);
 }
@@ -999,7 +1197,7 @@ class Map_assignment_statement : public Statement
  public:
   Map_assignment_statement(Expression* map_index,
                           Expression* val, Expression* should_set,
-                          source_location location)
+                          Location location)
     : Statement(STATEMENT_MAP_ASSIGNMENT, location),
       map_index_(map_index), val_(val), should_set_(should_set)
   { }
@@ -1010,14 +1208,17 @@ class Map_assignment_statement : public Statement
 
   bool
   do_traverse_assignments(Traverse_assignments*)
-  { gcc_unreachable(); }
+  { go_unreachable(); }
 
   Statement*
-  do_lower(Gogo*, Named_object*, Block*);
+  do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
+
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // A reference to the map index which should be set or deleted.
@@ -1042,9 +1243,10 @@ Map_assignment_statement::do_traverse(Traverse* traverse)
 // Lower a map assignment to a function call.
 
 Statement*
-Map_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
+Map_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
+                                  Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Map_index_expression* map_index = this->map_index_->map_index_expression();
   if (map_index == NULL)
@@ -1090,18 +1292,33 @@ Map_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
   Expression* p4 = Expression::make_temporary_reference(insert_temp, loc);
   Expression* call = Runtime::make_call(Runtime::MAPASSIGN2, loc, 4,
                                        p1, p2, p3, p4);
-  Statement* s = Statement::make_statement(call);
+  Statement* s = Statement::make_statement(call, true);
   b->add_statement(s);
 
   return Statement::make_block_statement(b, loc);
 }
 
+// Dump the AST representation for a map assignment statement.
+
+void
+Map_assignment_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(this->map_index_);
+  ast_dump_context->ostream() << " = ";
+  ast_dump_context->dump_expression(this->val_);
+  ast_dump_context->ostream() << ", ";
+  ast_dump_context->dump_expression(this->should_set_);
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a statement which assigns a pair of entries to a map.
 
 Statement*
 Statement::make_map_assignment(Expression* map_index,
                               Expression* val, Expression* should_set,
-                              source_location location)
+                              Location location)
 {
   return new Map_assignment_statement(map_index, val, should_set, location);
 }
@@ -1112,10 +1329,9 @@ class Tuple_receive_assignment_statement : public Statement
 {
  public:
   Tuple_receive_assignment_statement(Expression* val, Expression* closed,
-                                    Expression* channel, bool for_select,
-                                    source_location location)
+                                    Expression* channel, Location location)
     : Statement(STATEMENT_TUPLE_RECEIVE_ASSIGNMENT, location),
-      val_(val), closed_(closed), channel_(channel), for_select_(for_select)
+      val_(val), closed_(closed), channel_(channel)
   { }
 
  protected:
@@ -1124,14 +1340,17 @@ class Tuple_receive_assignment_statement : public Statement
 
   bool
   do_traverse_assignments(Traverse_assignments*)
-  { gcc_unreachable(); }
+  { go_unreachable(); }
 
   Statement*
-  do_lower(Gogo*, Named_object*, Block*);
+  do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // Lvalue which receives the value from the channel.
@@ -1140,8 +1359,6 @@ class Tuple_receive_assignment_statement : public Statement
   Expression* closed_;
   // The channel on which we receive the value.
   Expression* channel_;
-  // Whether this is for a select statement.
-  bool for_select_;
 };
 
 // Traversal.
@@ -1159,9 +1376,10 @@ Tuple_receive_assignment_statement::do_traverse(Traverse* traverse)
 
 Statement*
 Tuple_receive_assignment_statement::do_lower(Gogo*, Named_object*,
-                                            Block* enclosing)
+                                            Block* enclosing,
+                                            Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Channel_type* channel_type = this->channel_->type()->channel_type();
   if (channel_type == NULL)
@@ -1193,14 +1411,16 @@ Tuple_receive_assignment_statement::do_lower(Gogo*, Named_object*,
     Statement::make_temporary(Type::lookup_bool_type(), NULL, loc);
   b->add_statement(closed_temp);
 
-  // closed_temp = chanrecv[23](channel, &val_temp)
-  Expression* ref = Expression::make_temporary_reference(val_temp, loc);
+  // closed_temp = chanrecv2(type, channel, &val_temp)
+  Expression* td = Expression::make_type_descriptor(this->channel_->type(),
+                                                   loc);
+  Temporary_reference_expression* ref =
+    Expression::make_temporary_reference(val_temp, loc);
   Expression* p2 = Expression::make_unary(OPERATOR_AND, ref, loc);
-  Expression* call = Runtime::make_call((this->for_select_
-                                        ? Runtime::CHANRECV3
-                                        : Runtime::CHANRECV2),
-                                       loc, 2, this->channel_, p2);
+  Expression* call = Runtime::make_call(Runtime::CHANRECV2,
+                                       loc, 3, td, this->channel_, p2);
   ref = Expression::make_temporary_reference(closed_temp, loc);
+  ref->set_is_lvalue();
   Statement* s = Statement::make_assignment(ref, call, loc);
   b->add_statement(s);
 
@@ -1217,16 +1437,30 @@ Tuple_receive_assignment_statement::do_lower(Gogo*, Named_object*,
   return Statement::make_block_statement(b, loc);
 }
 
+// Dump the AST representation for a tuple receive statement.
+
+void
+Tuple_receive_assignment_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(this->val_);
+  ast_dump_context->ostream() << ", ";
+  ast_dump_context->dump_expression(this->closed_);
+  ast_dump_context->ostream() << " <- ";
+  ast_dump_context->dump_expression(this->channel_);
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a nonblocking receive statement.
 
 Statement*
 Statement::make_tuple_receive_assignment(Expression* val, Expression* closed,
                                         Expression* channel,
-                                        bool for_select,
-                                        source_location location)
+                                        Location location)
 {
   return new Tuple_receive_assignment_statement(val, closed, channel,
-                                               for_select, location);
+                                               location);
 }
 
 // An assignment to a pair of values from a type guard.  This is a
@@ -1237,7 +1471,7 @@ class Tuple_type_guard_assignment_statement : public Statement
  public:
   Tuple_type_guard_assignment_statement(Expression* val, Expression* ok,
                                        Expression* expr, Type* type,
-                                       source_location location)
+                                       Location location)
     : Statement(STATEMENT_TUPLE_TYPE_GUARD_ASSIGNMENT, location),
       val_(val), ok_(ok), expr_(expr), type_(type)
   { }
@@ -1248,14 +1482,17 @@ class Tuple_type_guard_assignment_statement : public Statement
 
   bool
   do_traverse_assignments(Traverse_assignments*)
-  { gcc_unreachable(); }
+  { go_unreachable(); }
 
   Statement*
-  do_lower(Gogo*, Named_object*, Block*);
+  do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
+
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   Call_expression*
@@ -1290,9 +1527,10 @@ Tuple_type_guard_assignment_statement::do_traverse(Traverse* traverse)
 
 Statement*
 Tuple_type_guard_assignment_statement::do_lower(Gogo*, Named_object*,
-                                               Block* enclosing)
+                                               Block* enclosing,
+                                               Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Type* expr_type = this->expr_->type();
   if (expr_type->interface_type() == NULL)
@@ -1357,7 +1595,7 @@ Tuple_type_guard_assignment_statement::do_lower(Gogo*, Named_object*,
 Call_expression*
 Tuple_type_guard_assignment_statement::lower_to_type(Runtime::Function code)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
   return Runtime::make_call(code, loc, 2,
                            Expression::make_type_descriptor(this->type_, loc),
                            this->expr_);
@@ -1370,7 +1608,7 @@ Tuple_type_guard_assignment_statement::lower_to_object_type(
     Block* b,
     Runtime::Function code)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   // var val_temp TYPE
   Temporary_statement* val_temp = Statement::make_temporary(this->type_,
@@ -1391,12 +1629,29 @@ Tuple_type_guard_assignment_statement::lower_to_object_type(
   b->add_statement(s);
 }
 
+// Dump the AST representation for a tuple type guard statement.
+
+void
+Tuple_type_guard_assignment_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(this->val_);
+  ast_dump_context->ostream() << ", ";
+  ast_dump_context->dump_expression(this->ok_);
+  ast_dump_context->ostream() << " = ";
+  ast_dump_context->dump_expression(this->expr_);
+  ast_dump_context->ostream() << " . ";
+  ast_dump_context->dump_type(this->type_);
+  ast_dump_context->ostream()  << std::endl;
+}
+
 // Make an assignment from a type guard to a pair of variables.
 
 Statement*
 Statement::make_tuple_type_guard_assignment(Expression* val, Expression* ok,
                                            Expression* expr, Type* type,
-                                           source_location location)
+                                           Location location)
 {
   return new Tuple_type_guard_assignment_statement(val, ok, expr, type,
                                                   location);
@@ -1407,11 +1662,15 @@ Statement::make_tuple_type_guard_assignment(Expression* val, Expression* ok,
 class Expression_statement : public Statement
 {
  public:
-  Expression_statement(Expression* expr)
+  Expression_statement(Expression* expr, bool is_ignored)
     : Statement(STATEMENT_EXPRESSION, expr->location()),
-      expr_(expr)
+      expr_(expr), is_ignored_(is_ignored)
   { }
 
+  Expression*
+  expr()
+  { return this->expr_; }
+
  protected:
   int
   do_traverse(Traverse* traverse)
@@ -1421,16 +1680,35 @@ class Expression_statement : public Statement
   do_determine_types()
   { this->expr_->determine_type_no_context(); }
 
+  void
+  do_check_types(Gogo*);
+
   bool
   do_may_fall_through() const;
 
-  tree
-  do_get_tree(Translate_context* context);
+  Bstatement*
+  do_get_backend(Translate_context* context);
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   Expression* expr_;
+  // Whether the value of this expression is being explicitly ignored.
+  bool is_ignored_;
 };
 
+// Check the types of an expression statement.  The only check we do
+// is to possibly give an error about discarding the value of the
+// expression.
+
+void
+Expression_statement::do_check_types(Gogo*)
+{
+  if (!this->is_ignored_)
+    this->expr_->discarding_value();
+}
+
 // An expression statement may fall through unless it is a call to a
 // function which does not return.
 
@@ -1464,21 +1742,30 @@ Expression_statement::do_may_fall_through() const
 
 // Convert to backend representation.
 
-tree
-Expression_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Expression_statement::do_get_backend(Translate_context* context)
 {
   tree expr_tree = this->expr_->get_tree(context);
-  Bexpression* bexpr = tree_to_expr(expr_tree);
-  Bstatement* ret = context->backend()->expression_statement(bexpr);
-  return stat_to_tree(ret);
+  return context->backend()->expression_statement(tree_to_expr(expr_tree));
+}
+
+// Dump the AST representation for an expression statement
+
+void
+Expression_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
+    const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(expr_);
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make an expression statement from an Expression.
 
 Statement*
-Statement::make_statement(Expression* expr)
+Statement::make_statement(Expression* expr, bool is_ignored)
 {
-  return new Expression_statement(expr);
+  return new Expression_statement(expr, is_ignored);
 }
 
 // A block statement--a list of statements which may include variable
@@ -1487,7 +1774,7 @@ Statement::make_statement(Expression* expr)
 class Block_statement : public Statement
 {
  public:
-  Block_statement(Block* block, source_location location)
+  Block_statement(Block* block, Location location)
     : Statement(STATEMENT_BLOCK, location),
       block_(block)
   { }
@@ -1505,8 +1792,11 @@ class Block_statement : public Statement
   do_may_fall_through() const
   { return this->block_->may_fall_through(); }
 
-  tree
-  do_get_tree(Translate_context* context);
+  Bstatement*
+  do_get_backend(Translate_context* context);
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   Block* block_;
@@ -1514,18 +1804,25 @@ class Block_statement : public Statement
 
 // Convert a block to the backend representation of a statement.
 
-tree
-Block_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Block_statement::do_get_backend(Translate_context* context)
 {
   Bblock* bblock = this->block_->get_backend(context);
-  Bstatement* ret = context->backend()->block_statement(bblock);
-  return stat_to_tree(ret);
+  return context->backend()->block_statement(bblock);
+}
+
+// Dump the AST for a block statement
+
+void
+Block_statement::do_dump_statement(Ast_dump_context*) const
+{
+  // block statement braces are dumped when traversing.
 }
 
 // Make a block statement.
 
 Statement*
-Statement::make_block_statement(Block* block, source_location location)
+Statement::make_block_statement(Block* block, Location location)
 {
   return new Block_statement(block, location);
 }
@@ -1547,14 +1844,17 @@ class Inc_dec_statement : public Statement
 
   bool
   do_traverse_assignments(Traverse_assignments*)
-  { gcc_unreachable(); }
+  { go_unreachable(); }
 
   Statement*
-  do_lower(Gogo*, Named_object*, Block*);
+  do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
 
-  tree
-  do_get_tree(Translate_context*)
-  { gcc_unreachable(); }
+  Bstatement*
+  do_get_backend(Translate_context*)
+  { go_unreachable(); }
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // The l-value to increment or decrement.
@@ -1566,9 +1866,9 @@ class Inc_dec_statement : public Statement
 // Lower to += or -=.
 
 Statement*
-Inc_dec_statement::do_lower(Gogo*, Named_object*, Block*)
+Inc_dec_statement::do_lower(Gogo*, Named_object*, Block*, Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   mpz_t oval;
   mpz_init_set_ui(oval, 1UL);
@@ -1579,6 +1879,16 @@ Inc_dec_statement::do_lower(Gogo*, Named_object*, Block*)
   return Statement::make_assignment_operation(op, this->expr_, oexpr, loc);
 }
 
+// Dump the AST representation for a inc/dec statement.
+
+void
+Inc_dec_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(expr_);
+  ast_dump_context->ostream() << (is_inc_? "++": "--") << std::endl;
+}
+
 // Make an increment statement.
 
 Statement*
@@ -1598,15 +1908,11 @@ Statement::make_dec_statement(Expression* expr)
 // Class Thunk_statement.  This is the base class for go and defer
 // statements.
 
-const char* const Thunk_statement::thunk_field_fn = "fn";
-
-const char* const Thunk_statement::thunk_field_receiver = "receiver";
-
 // Constructor.
 
 Thunk_statement::Thunk_statement(Statement_classification classification,
                                 Call_expression* call,
-                                source_location location)
+                                Location location)
     : Statement(classification, location),
       call_(call), struct_type_(NULL)
 {
@@ -1652,8 +1958,7 @@ Thunk_statement::is_simple(Function_type* fntype) const
   // If this calls something which is not a simple function, then we
   // need a thunk.
   Expression* fn = this->call_->call_expression()->fn();
-  if (fn->bound_method_expression() != NULL
-      || fn->interface_field_reference_expression() != NULL)
+  if (fn->interface_field_reference_expression() != NULL)
     return false;
 
   return true;
@@ -1708,14 +2013,6 @@ Thunk_statement::do_check_types(Gogo*)
        this->report_error("expected call expression");
       return;
     }
-  Function_type* fntype = ce->get_function_type();
-  if (fntype != NULL && fntype->is_method())
-    {
-      Expression* fn = ce->fn();
-      if (fn->bound_method_expression() == NULL
-         && fn->interface_field_reference_expression() == NULL)
-       this->report_error(_("no object for method call"));
-    }
 }
 
 // The Traverse class used to find and simplify thunk statements.
@@ -1746,7 +2043,7 @@ class Simplify_thunk_traverse : public Traverse
 int
 Simplify_thunk_traverse::function(Named_object* no)
 {
-  gcc_assert(this->function_ == NULL);
+  go_assert(this->function_ == NULL);
   this->function_ = no;
   int t = no->func_value()->traverse(this);
   this->function_ = NULL;
@@ -1781,6 +2078,29 @@ Gogo::simplify_thunk_statements()
   this->traverse(&thunk_traverse);
 }
 
+// Return true if the thunk function is a constant, which means that
+// it does not need to be passed to the thunk routine.
+
+bool
+Thunk_statement::is_constant_function() const
+{
+  Call_expression* ce = this->call_->call_expression();
+  Function_type* fntype = ce->get_function_type();
+  if (fntype == NULL)
+    {
+      go_assert(saw_errors());
+      return false;
+    }
+  if (fntype->is_builtin())
+    return true;
+  Expression* fn = ce->fn();
+  if (fn->func_expression() != NULL)
+    return fn->func_expression()->closure() == NULL;
+  if (fn->interface_field_reference_expression() != NULL)
+    return true;
+  return false;
+}
+
 // Simplify complex thunk statements into simple ones.  A complicated
 // thunk statement is one which takes anything other than zero
 // parameters or a single pointer parameter.  We rewrite it into code
@@ -1810,7 +2130,7 @@ Thunk_statement::simplify_statement(Gogo* gogo, Named_object* function,
   Function_type* fntype = ce->get_function_type();
   if (fntype == NULL)
     {
-      gcc_assert(saw_errors());
+      go_assert(saw_errors());
       this->set_is_error();
       return false;
     }
@@ -1818,17 +2138,15 @@ Thunk_statement::simplify_statement(Gogo* gogo, Named_object* function,
     return false;
 
   Expression* fn = ce->fn();
-  Bound_method_expression* bound_method = fn->bound_method_expression();
   Interface_field_reference_expression* interface_method =
     fn->interface_field_reference_expression();
-  const bool is_method = bound_method != NULL || interface_method != NULL;
 
-  source_location location = this->location();
+  Location location = this->location();
 
   std::string thunk_name = Gogo::thunk_name();
 
   // Build the thunk.
-  this->build_thunk(gogo, thunk_name, fntype);
+  this->build_thunk(gogo, thunk_name);
 
   // Generate code to call the thunk.
 
@@ -1836,38 +2154,11 @@ Thunk_statement::simplify_statement(Gogo* gogo, Named_object* function,
   // argument to the thunk.
 
   Expression_list* vals = new Expression_list();
-  if (fntype->is_builtin())
-    ;
-  else if (!is_method)
+  if (!this->is_constant_function())
     vals->push_back(fn);
-  else if (interface_method != NULL)
-    vals->push_back(interface_method->expr());
-  else if (bound_method != NULL)
-    {
-      vals->push_back(bound_method->method());
-      Expression* first_arg = bound_method->first_argument();
 
-      // We always pass a pointer when calling a method.
-      if (first_arg->type()->points_to() == NULL)
-       first_arg = Expression::make_unary(OPERATOR_AND, first_arg, location);
-
-      // If we are calling a method which was inherited from an
-      // embedded struct, and the method did not get a stub, then the
-      // first type may be wrong.
-      Type* fatype = bound_method->first_argument_type();
-      if (fatype != NULL)
-       {
-         if (fatype->points_to() == NULL)
-           fatype = Type::make_pointer_type(fatype);
-         Type* unsafe = Type::make_pointer_type(Type::make_void_type());
-         first_arg = Expression::make_cast(unsafe, first_arg, location);
-         first_arg = Expression::make_cast(fatype, first_arg, location);
-       }
-
-      vals->push_back(first_arg);
-    }
-  else
-    gcc_unreachable();
+  if (interface_method != NULL)
+    vals->push_back(interface_method->expr());
 
   if (ce->args() != NULL)
     {
@@ -1887,7 +2178,7 @@ Thunk_statement::simplify_statement(Gogo* gogo, Named_object* function,
 
   // Look up the thunk.
   Named_object* named_thunk = gogo->lookup(thunk_name, NULL);
-  gcc_assert(named_thunk != NULL && named_thunk->is_function());
+  go_assert(named_thunk != NULL && named_thunk->is_function());
 
   // Build the call.
   Expression* func = Expression::make_func_reference(named_thunk, NULL,
@@ -1903,11 +2194,11 @@ Thunk_statement::simplify_statement(Gogo* gogo, Named_object* function,
   else if (this->classification() == STATEMENT_DEFER)
     s = Statement::make_defer_statement(call, location);
   else
-    gcc_unreachable();
+    go_unreachable();
 
   // The current block should end with the go statement.
-  gcc_assert(block->statements()->size() >= 1);
-  gcc_assert(block->statements()->back() == this);
+  go_assert(block->statements()->size() >= 1);
+  go_assert(block->statements()->back() == this);
   block->replace_statement(block->statements()->size() - 1, s);
 
   // We already ran the determine_types pass, so we need to run it now
@@ -1935,52 +2226,40 @@ Thunk_statement::thunk_field_param(int n, char* buf, size_t buflen)
 Struct_type*
 Thunk_statement::build_struct(Function_type* fntype)
 {
-  source_location location = this->location();
+  Location location = this->location();
 
   Struct_field_list* fields = new Struct_field_list();
 
   Call_expression* ce = this->call_->call_expression();
   Expression* fn = ce->fn();
 
+  if (!this->is_constant_function())
+    {
+      // The function to call.
+      fields->push_back(Struct_field(Typed_identifier("fn", fntype,
+                                                     location)));
+    }
+
+  // If this thunk statement calls a method on an interface, we pass
+  // the interface object to the thunk.
   Interface_field_reference_expression* interface_method =
     fn->interface_field_reference_expression();
   if (interface_method != NULL)
     {
-      // If this thunk statement calls a method on an interface, we
-      // pass the interface object to the thunk.
-      Typed_identifier tid(Thunk_statement::thunk_field_fn,
-                          interface_method->expr()->type(),
+      Typed_identifier tid("object", interface_method->expr()->type(),
                           location);
       fields->push_back(Struct_field(tid));
     }
-  else if (!fntype->is_builtin())
-    {
-      // The function to call.
-      Typed_identifier tid(Go_statement::thunk_field_fn, fntype, location);
-      fields->push_back(Struct_field(tid));
-    }
-  else if (ce->is_recover_call())
+
+  // The predeclared recover function has no argument.  However, we
+  // add an argument when building recover thunks.  Handle that here.
+  if (ce->is_recover_call())
     {
-      // The predeclared recover function has no argument.  However,
-      // we add an argument when building recover thunks.  Handle that
-      // here.
       fields->push_back(Struct_field(Typed_identifier("can_recover",
                                                      Type::lookup_bool_type(),
                                                      location)));
     }
 
-  if (fn->bound_method_expression() != NULL)
-    {
-      gcc_assert(fntype->is_method());
-      Type* rtype = fntype->receiver()->type();
-      // We always pass the receiver as a pointer.
-      if (rtype->points_to() == NULL)
-       rtype = Type::make_pointer_type(rtype);
-      Typed_identifier tid(Thunk_statement::thunk_field_receiver, rtype,
-                          location);
-      fields->push_back(Struct_field(tid));
-    }
-
   const Expression_list* args = ce->args();
   if (args != NULL)
     {
@@ -2003,10 +2282,9 @@ Thunk_statement::build_struct(Function_type* fntype)
 // artificial, function.
 
 void
-Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name,
-                            Function_type* fntype)
+Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name)
 {
-  source_location location = this->location();
+  Location location = this->location();
 
   Call_expression* ce = this->call_->call_expression();
 
@@ -2054,12 +2332,14 @@ Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name,
   Named_object* function = gogo->start_function(thunk_name, thunk_type, true,
                                                location);
 
+  gogo->start_block(location);
+
   // For a defer statement, start with a call to
   // __go_set_defer_retaddr.  */
-  Label* retaddr_label = NULL; 
+  Label* retaddr_label = NULL;
   if (may_call_recover)
     {
-      retaddr_label = gogo->add_label_reference("retaddr");
+      retaddr_label = gogo->add_label_reference("retaddr", location, false);
       Expression* arg = Expression::make_label_addr(retaddr_label, location);
       Expression* call = Runtime::make_call(Runtime::SET_DEFER_RETADDR,
                                            location, 1, arg);
@@ -2080,7 +2360,7 @@ Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name,
 
   // Get a reference to the parameter.
   Named_object* named_parameter = gogo->lookup(parameter_name, NULL);
-  gcc_assert(named_parameter != NULL && named_parameter->is_variable());
+  go_assert(named_parameter != NULL && named_parameter->is_variable());
 
   // Build the call.  Note that the field names are the same as the
   // ones used in build_struct.
@@ -2089,43 +2369,33 @@ Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name,
   thunk_parameter = Expression::make_unary(OPERATOR_MULT, thunk_parameter,
                                           location);
 
-  Bound_method_expression* bound_method = ce->fn()->bound_method_expression();
   Interface_field_reference_expression* interface_method =
     ce->fn()->interface_field_reference_expression();
 
   Expression* func_to_call;
   unsigned int next_index;
-  if (!fntype->is_builtin())
+  if (this->is_constant_function())
     {
-      func_to_call = Expression::make_field_reference(thunk_parameter,
-                                                     0, location);
-      next_index = 1;
-    }
-  else
-    {
-      gcc_assert(bound_method == NULL && interface_method == NULL);
       func_to_call = ce->fn();
       next_index = 0;
     }
-
-  if (bound_method != NULL)
+  else
     {
-      Expression* r = Expression::make_field_reference(thunk_parameter, 1,
-                                                      location);
-      // The main program passes in a function pointer from the
-      // interface expression, so here we can make a bound method in
-      // all cases.
-      func_to_call = Expression::make_bound_method(r, func_to_call,
-                                                  location);
-      next_index = 2;
+      func_to_call = Expression::make_field_reference(thunk_parameter,
+                                                     0, location);
+      next_index = 1;
     }
-  else if (interface_method != NULL)
+
+  if (interface_method != NULL)
     {
       // The main program passes the interface object.
+      go_assert(next_index == 0);
+      Expression* r = Expression::make_field_reference(thunk_parameter, 0,
+                                                      location);
       const std::string& name(interface_method->name());
-      func_to_call = Expression::make_interface_field_reference(func_to_call,
-                                                               name,
+      func_to_call = Expression::make_interface_field_reference(r, name,
                                                                location);
+      next_index = 1;
     }
 
   Expression_list* call_params = new Expression_list();
@@ -2148,7 +2418,7 @@ Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name,
        call_params->push_back(param);
       else
        {
-         gcc_assert(call_params->empty());
+         go_assert(call_params->empty());
          recover_arg = param;
        }
     }
@@ -2159,25 +2429,16 @@ Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name,
       call_params = NULL;
     }
 
-  Expression* call = Expression::make_call(func_to_call, call_params, false,
-                                          location);
-  // We need to lower in case this is a builtin function.
-  call = call->lower(gogo, function, -1);
-  Call_expression* call_ce = call->call_expression();
-  if (call_ce != NULL && may_call_recover)
-    call_ce->set_is_deferred();
-
-  Statement* call_statement = Statement::make_statement(call);
-
-  // We already ran the determine_types pass, so we need to run it
-  // just for this statement now.
-  call_statement->determine_types();
+  Call_expression* call = Expression::make_call(func_to_call, call_params,
+                                               false, location);
 
-  // Sanity check.
-  call->check_types(gogo);
+  // This call expression was already lowered before entering the
+  // thunk statement.  Don't try to lower varargs again, as that will
+  // cause confusion for, e.g., method calls which already have a
+  // receiver parameter.
+  call->set_varargs_are_lowered();
 
-  if (call_ce != NULL && recover_arg != NULL)
-    call_ce->set_recover_arg(recover_arg);
+  Statement* call_statement = Statement::make_statement(call, true);
 
   gogo->add_statement(call_statement);
 
@@ -2192,11 +2453,36 @@ Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name,
       gogo->add_statement(Statement::make_return_statement(vals, location));
     }
 
-  // That is all the thunk has to do.
+  Block* b = gogo->finish_block(location);
+
+  gogo->add_block(b, location);
+
+  gogo->lower_block(function, b);
+
+  // We already ran the determine_types pass, so we need to run it
+  // just for the call statement now.  The other types are known.
+  call_statement->determine_types();
+
+  if (may_call_recover || recover_arg != NULL)
+    {
+      // Dig up the call expression, which may have been changed
+      // during lowering.
+      go_assert(call_statement->classification() == STATEMENT_EXPRESSION);
+      Expression_statement* es =
+       static_cast<Expression_statement*>(call_statement);
+      Call_expression* ce = es->expr()->call_expression();
+      go_assert(ce != NULL);
+      if (may_call_recover)
+       ce->set_is_deferred();
+      if (recover_arg != NULL)
+       ce->set_recover_arg(recover_arg);
+    }
+
+  // That is all the thunk has to do.
   gogo->finish_function(location);
 }
 
-// Get the function and argument trees.
+// Get the function and argument expressions.
 
 bool
 Thunk_statement::get_fn_and_arg(Expression** pfn, Expression** parg)
@@ -2213,7 +2499,7 @@ Thunk_statement::get_fn_and_arg(Expression** pfn, Expression** parg)
     *parg = Expression::make_nil(this->location());
   else
     {
-      gcc_assert(args->size() == 1);
+      go_assert(args->size() == 1);
       *parg = args->front();
     }
 
@@ -2222,56 +2508,76 @@ Thunk_statement::get_fn_and_arg(Expression** pfn, Expression** parg)
 
 // Class Go_statement.
 
-tree
-Go_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Go_statement::do_get_backend(Translate_context* context)
 {
   Expression* fn;
   Expression* arg;
   if (!this->get_fn_and_arg(&fn, &arg))
-    return error_mark_node;
+    return context->backend()->error_statement();
 
   Expression* call = Runtime::make_call(Runtime::GO, this->location(), 2,
                                        fn, arg);
   tree call_tree = call->get_tree(context);
   Bexpression* call_bexpr = tree_to_expr(call_tree);
-  Bstatement* ret = context->backend()->expression_statement(call_bexpr);
-  return stat_to_tree(ret);
+  return context->backend()->expression_statement(call_bexpr);
+}
+
+// Dump the AST representation for go statement.
+
+void
+Go_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "go ";
+  ast_dump_context->dump_expression(this->call());
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make a go statement.
 
 Statement*
-Statement::make_go_statement(Call_expression* call, source_location location)
+Statement::make_go_statement(Call_expression* call, Location location)
 {
   return new Go_statement(call, location);
 }
 
 // Class Defer_statement.
 
-tree
-Defer_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Defer_statement::do_get_backend(Translate_context* context)
 {
   Expression* fn;
   Expression* arg;
   if (!this->get_fn_and_arg(&fn, &arg))
-    return error_mark_node;
+    return context->backend()->error_statement();
 
-  source_location loc = this->location();
+  Location loc = this->location();
   Expression* ds = context->function()->func_value()->defer_stack(loc);
 
   Expression* call = Runtime::make_call(Runtime::DEFER, loc, 3,
                                        ds, fn, arg);
   tree call_tree = call->get_tree(context);
   Bexpression* call_bexpr = tree_to_expr(call_tree);
-  Bstatement* ret = context->backend()->expression_statement(call_bexpr);
-  return stat_to_tree(ret);
+  return context->backend()->expression_statement(call_bexpr);
+}
+
+// Dump the AST representation for defer statement.
+
+void
+Defer_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "defer ";
+  ast_dump_context->dump_expression(this->call());
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make a defer statement.
 
 Statement*
 Statement::make_defer_statement(Call_expression* call,
-                               source_location location)
+                               Location location)
 {
   return new Defer_statement(call, location);
 }
@@ -2297,14 +2603,14 @@ Return_statement::do_traverse_assignments(Traverse_assignments* tassign)
 
 // Lower a return statement.  If we are returning a function call
 // which returns multiple values which match the current function,
-// split up the call's results.  If the function has named result
-// variables, and the return statement lists explicit values, then
-// implement it by assigning the values to the result variables and
-// changing the statement to not list any values.  This lets
-// panic/recover work correctly.
+// split up the call's results.  If the return statement lists
+// explicit values, implement this statement by assigning the values
+// to the result variables and change this statement to a naked
+// return.  This lets panic/recover work correctly.
 
 Statement*
-Return_statement::do_lower(Gogo*, Named_object* function, Block* enclosing)
+Return_statement::do_lower(Gogo*, Named_object* function, Block* enclosing,
+                          Statement_inserter*)
 {
   if (this->is_lowered_)
     return this;
@@ -2313,7 +2619,7 @@ Return_statement::do_lower(Gogo*, Named_object* function, Block* enclosing)
   this->vals_ = NULL;
   this->is_lowered_ = true;
 
-  source_location loc = this->location();
+  Location loc = this->location();
 
   size_t vals_count = vals == NULL ? 0 : vals->size();
   Function::Results* results = function->func_value()->result_variables();
@@ -2385,7 +2691,12 @@ Return_statement::do_lower(Gogo*, Named_object* function, Block* enclosing)
       e->determine_type(&type_context);
 
       std::string reason;
-      if (Type::are_assignable(rvtype, e->type(), &reason))
+      bool ok;
+      if (this->are_hidden_fields_ok_)
+       ok = Type::are_assignable_hidden_ok(rvtype, e->type(), &reason);
+      else
+       ok = Type::are_assignable(rvtype, e->type(), &reason);
+      if (ok)
        {
          Expression* ve = Expression::make_var_reference(rv, e->location());
          lhs->push_back(ve);
@@ -2401,19 +2712,34 @@ Return_statement::do_lower(Gogo*, Named_object* function, Block* enclosing)
                     i, reason.c_str());
        }
     }
-  gcc_assert(lhs->size() == rhs->size());
+  go_assert(lhs->size() == rhs->size());
 
   if (lhs->empty())
     ;
   else if (lhs->size() == 1)
     {
-      b->add_statement(Statement::make_assignment(lhs->front(), rhs->front(),
-                                                 loc));
+      Statement* s = Statement::make_assignment(lhs->front(), rhs->front(),
+                                               loc);
+      if (this->are_hidden_fields_ok_)
+       {
+         Assignment_statement* as = static_cast<Assignment_statement*>(s);
+         as->set_hidden_fields_are_ok();
+       }
+      b->add_statement(s);
       delete lhs;
       delete rhs;
     }
   else
-    b->add_statement(Statement::make_tuple_assignment(lhs, rhs, loc));
+    {
+      Statement* s = Statement::make_tuple_assignment(lhs, rhs, loc);
+      if (this->are_hidden_fields_ok_)
+       {
+         Tuple_assignment_statement* tas =
+           static_cast<Tuple_assignment_statement*>(s);
+         tas->set_hidden_fields_are_ok();
+       }
+      b->add_statement(s);
+    }
 
   b->add_statement(this);
 
@@ -2424,10 +2750,10 @@ Return_statement::do_lower(Gogo*, Named_object* function, Block* enclosing)
 
 // Convert a return statement to the backend representation.
 
-tree
-Return_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Return_statement::do_get_backend(Translate_context* context)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Function* function = context->function()->func_value();
   tree fndecl = function->get_decl();
@@ -2446,17 +2772,26 @@ Return_statement::do_get_tree(Translate_context* context)
        }
     }
 
-  Bstatement* ret;
-  ret = context->backend()->return_statement(tree_to_function(fndecl),
-                                            retvals, loc);
-  return stat_to_tree(ret);
+  return context->backend()->return_statement(tree_to_function(fndecl),
+                                             retvals, loc);
+}
+
+// Dump the AST representation for a return statement.
+
+void
+Return_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "return " ;
+  ast_dump_context->dump_expression_list(this->vals_);
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make a return statement.
 
-Statement*
+Return_statement*
 Statement::make_return_statement(Expression_list* vals,
-                                source_location location)
+                                Location location)
 {
   return new Return_statement(vals, location);
 }
@@ -2466,7 +2801,7 @@ Statement::make_return_statement(Expression_list* vals,
 class Bc_statement : public Statement
 {
  public:
-  Bc_statement(bool is_break, Unnamed_label* label, source_location location)
+  Bc_statement(bool is_break, Unnamed_label* label, Location location)
     : Statement(STATEMENT_BREAK_OR_CONTINUE, location),
       label_(label), is_break_(is_break)
   { }
@@ -2484,11 +2819,12 @@ class Bc_statement : public Statement
   do_may_fall_through() const
   { return false; }
 
-  tree
-  do_get_tree(Translate_context* context)
-  {
-    return stat_to_tree(this->label_->get_goto(context, this->location()));
-  }
+  Bstatement*
+  do_get_backend(Translate_context* context)
+  { return this->label_->get_goto(context, this->location()); }
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // The label that this branches to.
@@ -2497,10 +2833,25 @@ class Bc_statement : public Statement
   bool is_break_;
 };
 
+// Dump the AST representation for a break/continue statement
+
+void
+Bc_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << (this->is_break_ ? "break" : "continue");
+  if (this->label_ != NULL)
+    {
+      ast_dump_context->ostream() << " ";
+      ast_dump_context->dump_label_name(this->label_);
+    }
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a break statement.
 
 Statement*
-Statement::make_break_statement(Unnamed_label* label, source_location location)
+Statement::make_break_statement(Unnamed_label* label, Location location)
 {
   return new Bc_statement(true, label, location);
 }
@@ -2509,7 +2860,7 @@ Statement::make_break_statement(Unnamed_label* label, source_location location)
 
 Statement*
 Statement::make_continue_statement(Unnamed_label* label,
-                                  source_location location)
+                                  Location location)
 {
   return new Bc_statement(false, label, location);
 }
@@ -2519,7 +2870,7 @@ Statement::make_continue_statement(Unnamed_label* label,
 class Goto_statement : public Statement
 {
  public:
-  Goto_statement(Label* label, source_location location)
+  Goto_statement(Label* label, Location location)
     : Statement(STATEMENT_GOTO, location),
       label_(label)
   { }
@@ -2536,8 +2887,11 @@ class Goto_statement : public Statement
   do_may_fall_through() const
   { return false; }
 
-  tree
-  do_get_tree(Translate_context*);
+  Bstatement*
+  do_get_backend(Translate_context*);
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   Label* label_;
@@ -2557,21 +2911,28 @@ Goto_statement::do_check_types(Gogo*)
     }
 }
 
-// Return the tree for the goto statement.
+// Convert the goto statement to the backend representation.
 
-tree
-Goto_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Goto_statement::do_get_backend(Translate_context* context)
 {
   Blabel* blabel = this->label_->get_backend_label(context);
-  Bstatement* statement = context->backend()->goto_statement(blabel,
-                                                            this->location());
-  return stat_to_tree(statement);
+  return context->backend()->goto_statement(blabel, this->location());
+}
+
+// Dump the AST representation for a goto statement.
+
+void
+Goto_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "goto " << this->label_->name() << std::endl;
 }
 
 // Make a goto statement.
 
 Statement*
-Statement::make_goto_statement(Label* label, source_location location)
+Statement::make_goto_statement(Label* label, Location location)
 {
   return new Goto_statement(label, location);
 }
@@ -2581,7 +2942,7 @@ Statement::make_goto_statement(Label* label, source_location location)
 class Goto_unnamed_statement : public Statement
 {
  public:
-  Goto_unnamed_statement(Unnamed_label* label, source_location location)
+  Goto_unnamed_statement(Unnamed_label* label, Location location)
     : Statement(STATEMENT_GOTO_UNNAMED, location),
       label_(label)
   { }
@@ -2595,21 +2956,34 @@ class Goto_unnamed_statement : public Statement
   do_may_fall_through() const
   { return false; }
 
-  tree
-  do_get_tree(Translate_context* context)
-  {
-    return stat_to_tree(this->label_->get_goto(context, this->location()));
-  }
+  Bstatement*
+  do_get_backend(Translate_context* context)
+  { return this->label_->get_goto(context, this->location()); }
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   Unnamed_label* label_;
 };
 
+// Dump the AST representation for an unnamed goto statement
+
+void
+Goto_unnamed_statement::do_dump_statement(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "goto ";
+  ast_dump_context->dump_label_name(this->label_);
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a goto statement to an unnamed label.
 
 Statement*
 Statement::make_goto_unnamed_statement(Unnamed_label* label,
-                                      source_location location)
+                                      Location location)
 {
   return new Goto_unnamed_statement(label, location);
 }
@@ -2624,21 +2998,29 @@ Label_statement::do_traverse(Traverse*)
   return TRAVERSE_CONTINUE;
 }
 
-// Return a tree defining this label.
+// Return the backend representation of the statement defining this
+// label.
 
-tree
-Label_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Label_statement::do_get_backend(Translate_context* context)
 {
   Blabel* blabel = this->label_->get_backend_label(context);
-  Bstatement* statement;
-  statement = context->backend()->label_definition_statement(blabel);
-  return stat_to_tree(statement);
+  return context->backend()->label_definition_statement(blabel);
+}
+
+// Dump the AST for a label definition statement.
+
+void
+Label_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << this->label_->name() << ":" << std::endl;
 }
 
 // Make a label statement.
 
 Statement*
-Statement::make_label_statement(Label* label, source_location location)
+Statement::make_label_statement(Label* label, Location location)
 {
   return new Label_statement(label, location);
 }
@@ -2658,15 +3040,29 @@ class Unnamed_label_statement : public Statement
   do_traverse(Traverse*)
   { return TRAVERSE_CONTINUE; }
 
-  tree
-  do_get_tree(Translate_context* context)
-  { return stat_to_tree(this->label_->get_definition(context)); }
+  Bstatement*
+  do_get_backend(Translate_context* context)
+  { return this->label_->get_definition(context); }
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // The label.
   Unnamed_label* label_;
 };
 
+// Dump the AST representation for an unnamed label definition statement.
+
+void
+Unnamed_label_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
+    const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_label_name(this->label_);
+  ast_dump_context->ostream() << ":" << std::endl;
+}
+
 // Make an unnamed label statement.
 
 Statement*
@@ -2681,7 +3077,7 @@ class If_statement : public Statement
 {
  public:
   If_statement(Expression* cond, Block* then_block, Block* else_block,
-              source_location location)
+              Location location)
     : Statement(STATEMENT_IF, location),
       cond_(cond), then_block_(then_block), else_block_(else_block)
   { }
@@ -2699,8 +3095,11 @@ class If_statement : public Statement
   bool
   do_may_fall_through() const;
 
-  tree
-  do_get_tree(Translate_context*);
+  Bstatement*
+  do_get_backend(Translate_context*);
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   Expression* cond_;
@@ -2756,31 +3155,49 @@ If_statement::do_may_fall_through() const
          || this->else_block_->may_fall_through());
 }
 
-// Get tree.
+// Get the backend representation.
 
-tree
-If_statement::do_get_tree(Translate_context* context)
+Bstatement*
+If_statement::do_get_backend(Translate_context* context)
 {
-  gcc_assert(this->cond_->type()->is_boolean_type()
+  go_assert(this->cond_->type()->is_boolean_type()
             || this->cond_->type()->is_error());
   tree cond_tree = this->cond_->get_tree(context);
+  Bexpression* cond_expr = tree_to_expr(cond_tree);
   Bblock* then_block = this->then_block_->get_backend(context);
   Bblock* else_block = (this->else_block_ == NULL
                        ? NULL
                        : this->else_block_->get_backend(context));
-  Bexpression* cond_expr = tree_to_expr(cond_tree);
-  
-  Bstatement* ret = context->backend()->if_statement(cond_expr, then_block,
-                                                    else_block,
-                                                    this->location());
-  return stat_to_tree(ret);
+  return context->backend()->if_statement(cond_expr, then_block,
+                                         else_block, this->location());
+}
+
+// Dump the AST representation for an if statement
+
+void
+If_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "if ";
+  ast_dump_context->dump_expression(this->cond_);
+  ast_dump_context->ostream() << std::endl;
+  if (ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->dump_block(this->then_block_);
+      if (this->else_block_ != NULL)
+       {
+         ast_dump_context->print_indent();
+         ast_dump_context->ostream() << "else" << std::endl;
+         ast_dump_context->dump_block(this->else_block_);
+       }
+    }
 }
 
 // Make an if statement.
 
 Statement*
 Statement::make_if_statement(Expression* cond, Block* then_block,
-                            Block* else_block, source_location location)
+                            Block* else_block, Location location)
 {
   return new If_statement(cond, then_block, else_block, location);
 }
@@ -2797,11 +3214,10 @@ class Case_clauses::Hash_integer_value
 size_t
 Case_clauses::Hash_integer_value::operator()(Expression* pe) const
 {
-  Type* itype;
+  Numeric_constant nc;
   mpz_t ival;
-  mpz_init(ival);
-  if (!pe->integer_constant_value(true, ival, &itype))
-    gcc_unreachable();
+  if (!pe->numeric_constant_value(&nc) || !nc.to_int(&ival))
+    go_unreachable();
   size_t ret = mpz_get_ui(ival);
   mpz_clear(ival);
   return ret;
@@ -2819,15 +3235,15 @@ class Case_clauses::Eq_integer_value
 bool
 Case_clauses::Eq_integer_value::operator()(Expression* a, Expression* b) const
 {
-  Type* atype;
-  Type* btype;
+  Numeric_constant anc;
   mpz_t aval;
+  Numeric_constant bnc;
   mpz_t bval;
-  mpz_init(aval);
-  mpz_init(bval);
-  if (!a->integer_constant_value(true, aval, &atype)
-      || !b->integer_constant_value(true, bval, &btype))
-    gcc_unreachable();
+  if (!a->numeric_constant_value(&anc)
+      || !anc.to_int(&aval)
+      || !b->numeric_constant_value(&bnc)
+      || !bnc.to_int(&bval))
+    go_unreachable();
   bool ret = mpz_cmp(aval, bval) == 0;
   mpz_clear(aval);
   mpz_clear(bval);
@@ -2882,11 +3298,11 @@ Case_clauses::Case_clause::lower(Block* b, Temporary_statement* val_temp,
                                 Unnamed_label* start_label,
                                 Unnamed_label* finish_label) const
 {
-  source_location loc = this->location_;
+  Location loc = this->location_;
   Unnamed_label* next_case_label;
   if (this->cases_ == NULL || this->cases_->empty())
     {
-      gcc_assert(this->is_default_);
+      go_assert(this->is_default_);
       next_case_label = NULL;
     }
   else
@@ -2914,7 +3330,7 @@ Case_clauses::Case_clause::lower(Block* b, Temporary_statement* val_temp,
        }
 
       Block* then_block = new Block(b, loc);
-      next_case_label = new Unnamed_label(UNKNOWN_LOCATION);
+      next_case_label = new Unnamed_label(Linemap::unknown_location());
       Statement* s = Statement::make_goto_unnamed_statement(next_case_label,
                                                            loc);
       then_block->add_statement(s);
@@ -3006,7 +3422,7 @@ Case_clauses::Case_clause::get_backend(Translate_context* context,
 {
   if (this->cases_ != NULL)
     {
-      gcc_assert(!this->is_default_);
+      go_assert(!this->is_default_);
       for (Expression_list::const_iterator p = this->cases_->begin();
           p != this->cases_->end();
           ++p)
@@ -3014,18 +3430,17 @@ Case_clauses::Case_clause::get_backend(Translate_context* context,
          Expression* e = *p;
          if (e->classification() != Expression::EXPRESSION_INTEGER)
            {
-             Type* itype;
+             Numeric_constant nc;
              mpz_t ival;
-             mpz_init(ival);
-             if (!(*p)->integer_constant_value(true, ival, &itype))
+             if (!(*p)->numeric_constant_value(&nc) || !nc.to_int(&ival))
                {
                  // Something went wrong.  This can happen with a
                  // negative constant and an unsigned switch value.
-                 gcc_assert(saw_errors());
+                 go_assert(saw_errors());
                  continue;
                }
-             gcc_assert(itype != NULL);
-             e = Expression::make_integer(&ival, itype, e->location());
+             go_assert(nc.type() != NULL);
+             e = Expression::make_integer(&ival, nc.type(), e->location());
              mpz_clear(ival);
            }
 
@@ -3035,7 +3450,7 @@ Case_clauses::Case_clause::get_backend(Translate_context* context,
            {
              // Value was already present.
              error_at(this->location_, "duplicate case in switch");
-             continue;
+             e = Expression::make_error(this->location_);
            }
 
          tree case_tree = e->get_tree(context);
@@ -3067,6 +3482,31 @@ Case_clauses::Case_clause::get_backend(Translate_context* context,
     return context->backend()->compound_statement(statements, break_stat);
 }
 
+// Dump the AST representation for a case clause
+
+void
+Case_clauses::Case_clause::dump_clause(Ast_dump_context* ast_dump_context)
+    const
+{
+  ast_dump_context->print_indent();
+  if (this->is_default_)
+    {
+      ast_dump_context->ostream() << "default:";
+    }
+  else
+    {
+      ast_dump_context->ostream() << "case ";
+      ast_dump_context->dump_expression_list(this->cases_);
+      ast_dump_context->ostream() << ":" ;
+    }
+  ast_dump_context->dump_block(this->statements_);
+  if (this->is_fallthrough_)
+    {
+      ast_dump_context->print_indent();
+      ast_dump_context->ostream() <<  " (fallthrough)" << std::endl;
+    }
+}
+
 // Class Case_clauses.
 
 // Traversal.
@@ -3152,7 +3592,6 @@ Case_clauses::lower(Block* b, Temporary_statement* val_temp,
   if (default_case != NULL)
     default_case->lower(b, val_temp, default_start_label,
                        default_finish_label);
-      
 }
 
 // Determine types.
@@ -3229,6 +3668,17 @@ Case_clauses::get_backend(Translate_context* context,
     }
 }
 
+// Dump the AST representation for case clauses (from a switch statement)
+
+void
+Case_clauses::dump_clauses(Ast_dump_context* ast_dump_context) const
+{
+  for (Clauses::const_iterator p = this->clauses_.begin();
+       p != this->clauses_.end();
+       ++p)
+    p->dump_clause(ast_dump_context);
+}
+
 // A constant switch statement.  A Switch_statement is lowered to this
 // when all the cases are constants.
 
@@ -3237,7 +3687,7 @@ class Constant_switch_statement : public Statement
  public:
   Constant_switch_statement(Expression* val, Case_clauses* clauses,
                            Unnamed_label* break_label,
-                           source_location location)
+                           Location location)
     : Statement(STATEMENT_CONSTANT_SWITCH, location),
       val_(val), clauses_(clauses), break_label_(break_label)
   { }
@@ -3255,8 +3705,11 @@ class Constant_switch_statement : public Statement
   bool
   do_may_fall_through() const;
 
-  tree
-  do_get_tree(Translate_context*);
+  Bstatement*
+  do_get_backend(Translate_context*);
+
+  void
+  do_dump_statement(Ast_dump_context*) const;
 
  private:
   // The value to switch on.
@@ -3313,8 +3766,8 @@ Constant_switch_statement::do_may_fall_through() const
 
 // Convert to GENERIC.
 
-tree
-Constant_switch_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Constant_switch_statement::do_get_backend(Translate_context* context)
 {
   tree switch_val_tree = this->val_->get_tree(context);
   Bexpression* switch_val_expr = tree_to_expr(switch_val_tree);
@@ -3334,9 +3787,27 @@ Constant_switch_statement::do_get_tree(Translate_context* context)
                                                          all_statements,
                                                          this->location());
   Bstatement* ldef = break_label->get_definition(context);
-  Bstatement* ret = context->backend()->compound_statement(switch_statement,
-                                                          ldef);
-  return stat_to_tree(ret);
+  return context->backend()->compound_statement(switch_statement, ldef);
+}
+
+// Dump the AST representation for a constant switch statement.
+
+void
+Constant_switch_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
+    const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "switch ";
+  ast_dump_context->dump_expression(this->val_);
+
+  if (ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->ostream() << " {" << std::endl;
+      this->clauses_->dump_clauses(ast_dump_context);
+      ast_dump_context->ostream() << "}";
+    }
+
+   ast_dump_context->ostream() << std::endl;
 }
 
 // Class Switch_statement.
@@ -3358,9 +3829,10 @@ Switch_statement::do_traverse(Traverse* traverse)
 // of if statements.
 
 Statement*
-Switch_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
+Switch_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
+                          Statement_inserter*)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   if (this->val_ != NULL
       && (this->val_->is_error_expression()
@@ -3381,7 +3853,7 @@ Switch_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
       Expression* val = this->val_;
       if (val == NULL)
        val = Expression::make_boolean(true, loc);
-      return Statement::make_statement(val);
+      return Statement::make_statement(val, true);
     }
 
   Temporary_statement* val_temp;
@@ -3413,10 +3885,31 @@ Switch_statement::break_label()
   return this->break_label_;
 }
 
+// Dump the AST representation for a switch statement.
+
+void
+Switch_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "switch ";
+  if (this->val_ != NULL)
+    {
+      ast_dump_context->dump_expression(this->val_);
+    }
+  if (ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->ostream() << " {" << std::endl;
+      this->clauses_->dump_clauses(ast_dump_context);
+      ast_dump_context->print_indent();
+      ast_dump_context->ostream() << "}";
+    }
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a switch statement.
 
 Switch_statement*
-Statement::make_switch_statement(Expression* val, source_location location)
+Statement::make_switch_statement(Expression* val, Location location)
 {
   return new Switch_statement(val, location);
 }
@@ -3445,18 +3938,33 @@ Type_case_clauses::Type_case_clause::traverse(Traverse* traverse)
 // statements.
 
 void
-Type_case_clauses::Type_case_clause::lower(Block* b,
+Type_case_clauses::Type_case_clause::lower(Type* switch_val_type,
+                                          Block* b,
                                           Temporary_statement* descriptor_temp,
                                           Unnamed_label* break_label,
                                           Unnamed_label** stmts_label) const
 {
-  source_location loc = this->location_;
+  Location loc = this->location_;
 
   Unnamed_label* next_case_label = NULL;
   if (!this->is_default_)
     {
       Type* type = this->type_;
 
+      std::string reason;
+      if (switch_val_type->interface_type() != NULL
+         && !type->is_nil_constant_as_type()
+         && type->interface_type() == NULL
+         && !switch_val_type->interface_type()->implements_interface(type,
+                                                                     &reason))
+       {
+         if (reason.empty())
+           error_at(this->location_, "impossible type switch case");
+         else
+           error_at(this->location_, "impossible type switch case (%s)",
+                    reason.c_str());
+       }
+
       Expression* ref = Expression::make_temporary_reference(descriptor_temp,
                                                             loc);
 
@@ -3480,16 +3988,16 @@ Type_case_clauses::Type_case_clause::lower(Block* b,
       if (!this->is_fallthrough_)
        {
          // if !COND { goto NEXT_CASE_LABEL }
-         next_case_label = new Unnamed_label(UNKNOWN_LOCATION);
+         next_case_label = new Unnamed_label(Linemap::unknown_location());
          dest = next_case_label;
          cond = Expression::make_unary(OPERATOR_NOT, cond, loc);
        }
       else
        {
          // if COND { goto STMTS_LABEL }
-         gcc_assert(stmts_label != NULL);
+         go_assert(stmts_label != NULL);
          if (*stmts_label == NULL)
-           *stmts_label = new Unnamed_label(UNKNOWN_LOCATION);
+           *stmts_label = new Unnamed_label(Linemap::unknown_location());
          dest = *stmts_label;
        }
       Block* then_block = new Block(b, loc);
@@ -3504,10 +4012,10 @@ Type_case_clauses::Type_case_clause::lower(Block* b,
          && stmts_label != NULL
          && *stmts_label != NULL))
     {
-      gcc_assert(!this->is_fallthrough_);
+      go_assert(!this->is_fallthrough_);
       if (stmts_label != NULL && *stmts_label != NULL)
        {
-         gcc_assert(!this->is_default_);
+         go_assert(!this->is_default_);
          if (this->statements_ != NULL)
            (*stmts_label)->set_location(this->statements_->start_location());
          Statement* s = Statement::make_unnamed_label_statement(*stmts_label);
@@ -3520,10 +4028,10 @@ Type_case_clauses::Type_case_clause::lower(Block* b,
     }
 
   if (this->is_fallthrough_)
-    gcc_assert(next_case_label == NULL);
+    go_assert(next_case_label == NULL);
   else
     {
-      source_location gloc = (this->statements_ == NULL
+      Location gloc = (this->statements_ == NULL
                              ? loc
                              : this->statements_->end_location());
       b->add_statement(Statement::make_goto_unnamed_statement(break_label,
@@ -3537,6 +4045,31 @@ Type_case_clauses::Type_case_clause::lower(Block* b,
     }
 }
 
+// Dump the AST representation for a type case clause
+
+void
+Type_case_clauses::Type_case_clause::dump_clause(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  if (this->is_default_)
+    {
+      ast_dump_context->ostream() << "default:";
+    }
+  else
+    {
+      ast_dump_context->ostream() << "case ";
+      ast_dump_context->dump_type(this->type_);
+      ast_dump_context->ostream() << ":" ;
+    }
+  ast_dump_context->dump_block(this->statements_);
+  if (this->is_fallthrough_)
+    {
+      ast_dump_context->print_indent();
+      ast_dump_context->ostream() <<  " (fallthrough)" << std::endl;
+    }
+}
+
 // Class Type_case_clauses.
 
 // Traversal.
@@ -3582,7 +4115,8 @@ Type_case_clauses::check_duplicates() const
 // BREAK_LABEL is the label at the end of the type switch.
 
 void
-Type_case_clauses::lower(Block* b, Temporary_statement* descriptor_temp,
+Type_case_clauses::lower(Type* switch_val_type, Block* b,
+                        Temporary_statement* descriptor_temp,
                         Unnamed_label* break_label) const
 {
   const Type_case_clause* default_case = NULL;
@@ -3593,7 +4127,8 @@ Type_case_clauses::lower(Block* b, Temporary_statement* descriptor_temp,
        ++p)
     {
       if (!p->is_default())
-       p->lower(b, descriptor_temp, break_label, &stmts_label);
+       p->lower(switch_val_type, b, descriptor_temp, break_label,
+                &stmts_label);
       else
        {
          // We are generating a series of tests, which means that we
@@ -3601,10 +4136,22 @@ Type_case_clauses::lower(Block* b, Temporary_statement* descriptor_temp,
          default_case = &*p;
        }
     }
-  gcc_assert(stmts_label == NULL);
+  go_assert(stmts_label == NULL);
 
   if (default_case != NULL)
-    default_case->lower(b, descriptor_temp, break_label, NULL);
+    default_case->lower(switch_val_type, b, descriptor_temp, break_label,
+                       NULL);
+}
+
+// Dump the AST representation for case clauses (from a switch statement)
+
+void
+Type_case_clauses::dump_clauses(Ast_dump_context* ast_dump_context) const
+{
+  for (Type_clauses::const_iterator p = this->clauses_.begin();
+       p != this->clauses_.end();
+       ++p)
+    p->dump_clause(ast_dump_context);
 }
 
 // Class Type_switch_statement.
@@ -3631,9 +4178,10 @@ Type_switch_statement::do_traverse(Traverse* traverse)
 // equality testing.
 
 Statement*
-Type_switch_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
+Type_switch_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
+                               Statement_inserter*)
 {
-  const source_location loc = this->location();
+  const Location loc = this->location();
 
   if (this->clauses_ != NULL)
     this->clauses_->check_duplicates();
@@ -3682,14 +4230,15 @@ Type_switch_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
                                             ? Runtime::EFACETYPE
                                             : Runtime::IFACETYPE),
                                            loc, 1, ref);
-      Expression* lhs = Expression::make_temporary_reference(descriptor_temp,
-                                                            loc);
+      Temporary_reference_expression* lhs =
+       Expression::make_temporary_reference(descriptor_temp, loc);
+      lhs->set_is_lvalue();
       Statement* s = Statement::make_assignment(lhs, call, loc);
       b->add_statement(s);
     }
 
   if (this->clauses_ != NULL)
-    this->clauses_->lower(b, descriptor_temp, this->break_label());
+    this->clauses_->lower(val_type, b, descriptor_temp, this->break_label());
 
   Statement* s = Statement::make_unnamed_label_statement(this->break_label_);
   b->add_statement(s);
@@ -3708,11 +4257,30 @@ Type_switch_statement::break_label()
   return this->break_label_;
 }
 
+// Dump the AST representation for a type switch statement
+
+void
+Type_switch_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
+    const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "switch " << this->var_->name() << " = ";
+  ast_dump_context->dump_expression(this->expr_);
+  ast_dump_context->ostream() << " .(type)";
+  if (ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->ostream() << " {" << std::endl;
+      this->clauses_->dump_clauses(ast_dump_context);
+      ast_dump_context->ostream() << "}";
+    }
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a type switch statement.
 
 Type_switch_statement*
 Statement::make_type_switch_statement(Named_object* var, Expression* expr,
-                                     source_location location)
+                                     Location location)
 {
   return new Type_switch_statement(var, expr, location);
 }
@@ -3773,12 +4341,12 @@ Send_statement::do_check_types(Gogo*)
     }
 }
 
-// Get a tree for a send statement.
+// Convert a send statement to the backend representation.
 
-tree
-Send_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Send_statement::do_get_backend(Translate_context* context)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Channel_type* channel_type = this->channel_->type()->channel_type();
   Type* element_type = channel_type->element_type();
@@ -3813,7 +4381,7 @@ Send_statement::do_get_tree(Translate_context* context)
 
     case Type::TYPE_ARRAY:
       is_small = false;
-      can_take_address = !element_type->is_open_array_type();
+      can_take_address = !element_type->is_slice_type();
       break;
 
     default:
@@ -3823,8 +4391,8 @@ Send_statement::do_get_tree(Translate_context* context)
     case Type::TYPE_NIL:
     case Type::TYPE_NAMED:
     case Type::TYPE_FORWARD:
-      gcc_assert(saw_errors());
-      return error_mark_node;
+      go_assert(saw_errors());
+      return context->backend()->error_statement();
     }
 
   // Only try to take the address of a variable.  We have already
@@ -3835,9 +4403,11 @@ Send_statement::do_get_tree(Translate_context* context)
       && val->temporary_reference_expression() == NULL)
     can_take_address = false;
 
+  Expression* td = Expression::make_type_descriptor(this->channel_->type(),
+                                                   loc);
+
   Runtime::Function code;
   Bstatement* btemp = NULL;
-  Expression* call;
   if (is_small)
       {
        // Type is small enough to handle as uint64.
@@ -3862,27 +4432,38 @@ Send_statement::do_get_tree(Translate_context* context)
                                                            val, loc);
       Expression* ref = Expression::make_temporary_reference(temp, loc);
       val = Expression::make_unary(OPERATOR_AND, ref, loc);
-      btemp = tree_to_stat(temp->get_tree(context));
+      btemp = temp->get_backend(context);
     }
 
-  call = Runtime::make_call(code, loc, 3, this->channel_, val,
-                           Expression::make_boolean(this->for_select_, loc));
+  Expression* call = Runtime::make_call(code, loc, 3, td, this->channel_, val);
 
-  context->gogo()->lower_expression(context->function(), &call);
+  context->gogo()->lower_expression(context->function(), NULL, &call);
   Bexpression* bcall = tree_to_expr(call->get_tree(context));
   Bstatement* s = context->backend()->expression_statement(bcall);
 
   if (btemp == NULL)
-    return stat_to_tree(s);
+    return s;
   else
-    return stat_to_tree(context->backend()->compound_statement(btemp, s));
+    return context->backend()->compound_statement(btemp, s);
+}
+
+// Dump the AST representation for a send statement
+
+void
+Send_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->dump_expression(this->channel_);
+  ast_dump_context->ostream() << " <- ";
+  ast_dump_context->dump_expression(this->val_);
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make a send statement.
 
 Send_statement*
 Statement::make_send_statement(Expression* channel, Expression* val,
-                              source_location location)
+                              Location location)
 {
   return new Send_statement(channel, val, location);
 }
@@ -3922,118 +4503,178 @@ Select_clauses::Select_clause::traverse(Traverse* traverse)
   return TRAVERSE_CONTINUE;
 }
 
-// Lowering.  Here we pull out the channel and the send values, to
-// enforce the order of evaluation.  We also add explicit send and
-// receive statements to the clauses.
+// Lowering.  We call a function to register this clause, and arrange
+// to set any variables in any receive clause.
 
 void
 Select_clauses::Select_clause::lower(Gogo* gogo, Named_object* function,
-                                    Block* b)
+                                    Block* b, Temporary_statement* sel)
 {
+  Location loc = this->location_;
+
+  Expression* selref = Expression::make_temporary_reference(sel, loc);
+
+  mpz_t ival;
+  mpz_init_set_ui(ival, this->index_);
+  Expression* index_expr = Expression::make_integer(&ival, NULL, loc);
+  mpz_clear(ival);
+
   if (this->is_default_)
     {
-      gcc_assert(this->channel_ == NULL && this->val_ == NULL);
+      go_assert(this->channel_ == NULL && this->val_ == NULL);
+      this->lower_default(b, selref, index_expr);
       this->is_lowered_ = true;
       return;
     }
 
-  source_location loc = this->location_;
-
   // Evaluate the channel before the select statement.
   Temporary_statement* channel_temp = Statement::make_temporary(NULL,
                                                                this->channel_,
                                                                loc);
   b->add_statement(channel_temp);
-  this->channel_ = Expression::make_temporary_reference(channel_temp, loc);
+  Expression* chanref = Expression::make_temporary_reference(channel_temp,
+                                                            loc);
+
+  if (this->is_send_)
+    this->lower_send(b, selref, chanref, index_expr);
+  else
+    this->lower_recv(gogo, function, b, selref, chanref, index_expr);
+
+  // Now all references should be handled through the statements, not
+  // through here.
+  this->is_lowered_ = true;
+  this->val_ = NULL;
+  this->var_ = NULL;
+}
+
+// Lower a default clause in a select statement.
+
+void
+Select_clauses::Select_clause::lower_default(Block* b, Expression* selref,
+                                            Expression* index_expr)
+{
+  Location loc = this->location_;
+  Expression* call = Runtime::make_call(Runtime::SELECTDEFAULT, loc, 2, selref,
+                                       index_expr);
+  b->add_statement(Statement::make_statement(call, true));
+}
+
+// Lower a send clause in a select statement.
+
+void
+Select_clauses::Select_clause::lower_send(Block* b, Expression* selref,
+                                         Expression* chanref,
+                                         Expression* index_expr)
+{
+  Location loc = this->location_;
+
+  Channel_type* ct = this->channel_->type()->channel_type();
+  if (ct == NULL)
+    return;
+
+  Type* valtype = ct->element_type();
+
+  // Note that copying the value to a temporary here means that we
+  // evaluate the send values in the required order.
+  Temporary_statement* val = Statement::make_temporary(valtype, this->val_,
+                                                      loc);
+  b->add_statement(val);
+
+  Expression* valref = Expression::make_temporary_reference(val, loc);
+  Expression* valaddr = Expression::make_unary(OPERATOR_AND, valref, loc);
+
+  Expression* call = Runtime::make_call(Runtime::SELECTSEND, loc, 4, selref,
+                                       chanref, valaddr, index_expr);
+  b->add_statement(Statement::make_statement(call, true));
+}
 
-  // If this is a send clause, evaluate the value to send before the
-  // select statement.
-  Temporary_statement* val_temp = NULL;
-  if (this->is_send_ && !this->val_->is_constant())
+// Lower a receive clause in a select statement.
+
+void
+Select_clauses::Select_clause::lower_recv(Gogo* gogo, Named_object* function,
+                                         Block* b, Expression* selref,
+                                         Expression* chanref,
+                                         Expression* index_expr)
+{
+  Location loc = this->location_;
+
+  Channel_type* ct = this->channel_->type()->channel_type();
+  if (ct == NULL)
+    return;
+
+  Type* valtype = ct->element_type();
+  Temporary_statement* val = Statement::make_temporary(valtype, NULL, loc);
+  b->add_statement(val);
+
+  Expression* valref = Expression::make_temporary_reference(val, loc);
+  Expression* valaddr = Expression::make_unary(OPERATOR_AND, valref, loc);
+
+  Temporary_statement* closed_temp = NULL;
+
+  Expression* call;
+  if (this->closed_ == NULL && this->closedvar_ == NULL)
+    call = Runtime::make_call(Runtime::SELECTRECV, loc, 4, selref, chanref,
+                             valaddr, index_expr);
+  else
     {
-      val_temp = Statement::make_temporary(NULL, this->val_, loc);
-      b->add_statement(val_temp);
+      closed_temp = Statement::make_temporary(Type::lookup_bool_type(), NULL,
+                                             loc);
+      b->add_statement(closed_temp);
+      Expression* cref = Expression::make_temporary_reference(closed_temp,
+                                                             loc);
+      Expression* caddr = Expression::make_unary(OPERATOR_AND, cref, loc);
+      call = Runtime::make_call(Runtime::SELECTRECV2, loc, 5, selref, chanref,
+                               valaddr, caddr, index_expr);
     }
 
-  // Add the send or receive before the rest of the statements if any.
-  Block *init = new Block(b, loc);
-  Expression* ref = Expression::make_temporary_reference(channel_temp, loc);
-  if (this->is_send_)
+  b->add_statement(Statement::make_statement(call, true));
+
+  // If the block of statements is executed, arrange for the received
+  // value to move from VAL to the place where the statements expect
+  // it.
+
+  Block* init = NULL;
+
+  if (this->var_ != NULL)
     {
-      Expression* ref2;
-      if (val_temp == NULL)
-       ref2 = this->val_;
-      else
-       ref2 = Expression::make_temporary_reference(val_temp, loc);
-      Send_statement* send = Statement::make_send_statement(ref, ref2, loc);
-      send->set_for_select();
-      init->add_statement(send);
+      go_assert(this->val_ == NULL);
+      valref = Expression::make_temporary_reference(val, loc);
+      this->var_->var_value()->set_init(valref);
+      this->var_->var_value()->clear_type_from_chan_element();
     }
-  else if (this->closed_ != NULL && !this->closed_->is_sink_expression())
+  else if (this->val_ != NULL && !this->val_->is_sink_expression())
     {
-      gcc_assert(this->var_ == NULL && this->closedvar_ == NULL);
-      if (this->val_ == NULL)
-       this->val_ = Expression::make_sink(loc);
-      Statement* s = Statement::make_tuple_receive_assignment(this->val_,
-                                                             this->closed_,
-                                                             ref, true, loc);
-      init->add_statement(s);
+      init = new Block(b, loc);
+      valref = Expression::make_temporary_reference(val, loc);
+      init->add_statement(Statement::make_assignment(this->val_, valref, loc));
     }
-  else if (this->closedvar_ != NULL)
+
+  if (this->closedvar_ != NULL)
     {
-      gcc_assert(this->val_ == NULL);
-      Expression* val;
-      if (this->var_ == NULL)
-       val = Expression::make_sink(loc);
-      else
-       val = Expression::make_var_reference(this->var_, loc);
-      Expression* closed = Expression::make_var_reference(this->closedvar_,
-                                                         loc);
-      Statement* s = Statement::make_tuple_receive_assignment(val, closed, ref,
-                                                             true, loc);
-      // We have to put S in STATEMENTS_, because that is where the
-      // variables are declared.
-      gcc_assert(this->statements_ != NULL);
-      this->statements_->add_statement_at_front(s);
-      // We have to lower STATEMENTS_ again, to lower the tuple
-      // receive assignment we just added.
-      gogo->lower_block(function, this->statements_);
+      go_assert(this->closed_ == NULL);
+      Expression* cref = Expression::make_temporary_reference(closed_temp,
+                                                             loc);
+      this->closedvar_->var_value()->set_init(cref);
     }
-  else
+  else if (this->closed_ != NULL && !this->closed_->is_sink_expression())
     {
-      Receive_expression* recv = Expression::make_receive(ref, loc);
-      recv->set_for_select();
-      if (this->val_ != NULL)
-       {
-         gcc_assert(this->var_ == NULL);
-         init->add_statement(Statement::make_assignment(this->val_, recv,
-                                                        loc));
-       }
-      else if (this->var_ != NULL)
-       {
-         this->var_->var_value()->set_init(recv);
-         this->var_->var_value()->clear_type_from_chan_element();
-       }
-      else
-       {
-         init->add_statement(Statement::make_statement(recv));
-       }
+      if (init == NULL)
+       init = new Block(b, loc);
+      Expression* cref = Expression::make_temporary_reference(closed_temp,
+                                                             loc);
+      init->add_statement(Statement::make_assignment(this->closed_, cref,
+                                                    loc));
     }
 
-  // Lower any statements we just created.
-  gogo->lower_block(function, init);
-
-  if (this->statements_ != NULL)
-    init->add_statement(Statement::make_block_statement(this->statements_,
-                                                       loc));
-
-  this->statements_ = init;
+  if (init != NULL)
+    {
+      gogo->lower_block(function, init);
 
-  // Now all references should be handled through the statements, not
-  // through here.
-  this->is_lowered_ = true;
-  this->val_ = NULL;
-  this->var_ = NULL;
+      if (this->statements_ != NULL)
+       init->add_statement(Statement::make_block_statement(this->statements_,
+                                                           loc));
+      this->statements_ = init;
+    }
 }
 
 // Determine types.
@@ -4041,11 +4682,32 @@ Select_clauses::Select_clause::lower(Gogo* gogo, Named_object* function,
 void
 Select_clauses::Select_clause::determine_types()
 {
-  gcc_assert(this->is_lowered_);
+  go_assert(this->is_lowered_);
   if (this->statements_ != NULL)
     this->statements_->determine_types();
 }
 
+// Check types.
+
+void
+Select_clauses::Select_clause::check_types()
+{
+  if (this->is_default_)
+    return;
+
+  Channel_type* ct = this->channel_->type()->channel_type();
+  if (ct == NULL)
+    {
+      error_at(this->channel_->location(), "expected channel");
+      return;
+    }
+
+  if (this->is_send_ && !ct->may_send())
+    error_at(this->location(), "invalid send on receive-only channel");
+  else if (!this->is_send_ && !ct->may_receive())
+    error_at(this->location(), "invalid receive on send-only channel");
+}
+
 // Whether this clause may fall through to the statement which follows
 // the overall select statement.
 
@@ -4057,7 +4719,7 @@ Select_clauses::Select_clause::may_fall_through() const
   return this->statements_->may_fall_through();
 }
 
-// Return a tree for the statements to execute.
+// Return the backend representation for the statements to execute.
 
 Bstatement*
 Select_clauses::Select_clause::get_statements_backend(
@@ -4069,6 +4731,48 @@ Select_clauses::Select_clause::get_statements_backend(
   return context->backend()->block_statement(bblock);
 }
 
+// Dump the AST representation for a select case clause
+
+void
+Select_clauses::Select_clause::dump_clause(
+    Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  if (this->is_default_)
+    {
+      ast_dump_context->ostream() << "default:";
+    }
+  else
+    {
+      ast_dump_context->ostream() << "case "  ;
+      if (this->is_send_)
+        {
+          ast_dump_context->dump_expression(this->channel_);
+          ast_dump_context->ostream() << " <- " ;
+         if (this->val_ != NULL)
+           ast_dump_context->dump_expression(this->val_);
+        }
+      else
+        {
+         if (this->val_ != NULL)
+           ast_dump_context->dump_expression(this->val_);
+          if (this->closed_ != NULL)
+            {
+             // FIXME: can val_ == NULL and closed_ ! = NULL?
+              ast_dump_context->ostream() << " , " ;
+              ast_dump_context->dump_expression(this->closed_);
+            }
+          if (this->closedvar_ != NULL || this->var_ != NULL)
+            ast_dump_context->ostream() << " := " ;
+
+          ast_dump_context->ostream() << " <- " ;
+          ast_dump_context->dump_expression(this->channel_);
+        }
+      ast_dump_context->ostream() << ":" ;
+    }
+  ast_dump_context->dump_block(this->statements_);
+}
+
 // Class Select_clauses.
 
 // Traversal.
@@ -4091,12 +4795,13 @@ Select_clauses::traverse(Traverse* traverse)
 // receive statements to the clauses.
 
 void
-Select_clauses::lower(Gogo* gogo, Named_object* function, Block* b)
+Select_clauses::lower(Gogo* gogo, Named_object* function, Block* b,
+                     Temporary_statement* sel)
 {
   for (Clauses::iterator p = this->clauses_.begin();
        p != this->clauses_.end();
        ++p)
-    p->lower(gogo, function, b);
+    p->lower(gogo, function, b, sel);
 }
 
 // Determine types.
@@ -4110,6 +4815,17 @@ Select_clauses::determine_types()
     p->determine_types();
 }
 
+// Check types.
+
+void
+Select_clauses::check_types()
+{
+  for (Clauses::iterator p = this->clauses_.begin();
+       p != this->clauses_.end();
+       ++p)
+    p->check_types();
+}
+
 // Return whether these select clauses fall through to the statement
 // following the overall select statement.
 
@@ -4124,179 +4840,55 @@ Select_clauses::may_fall_through() const
   return false;
 }
 
-// Convert to the backend representation.  We build a call to
-//   size_t __go_select(size_t count, _Bool has_default,
-//                      channel* channels, _Bool* is_send)
-//
-// There are COUNT entries in the CHANNELS and IS_SEND arrays.  The
-// value in the IS_SEND array is true for send, false for receive.
-// __go_select returns an integer from 0 to COUNT, inclusive.  A
-// return of 0 means that the default case should be run; this only
-// happens if HAS_DEFAULT is non-zero.  Otherwise the number indicates
-// the case to run.
-
-// FIXME: This doesn't handle channels which send interface types
-// where the receiver has a static type which matches that interface.
+// Convert to the backend representation.  We have already accumulated
+// all the select information.  Now we call selectgo, which will
+// return the index of the clause to execute.
 
 Bstatement*
 Select_clauses::get_backend(Translate_context* context,
+                           Temporary_statement* sel,
                            Unnamed_label *break_label,
-                           source_location location)
+                           Location location)
 {
   size_t count = this->clauses_.size();
+  std::vector<std::vector<Bexpression*> > cases(count);
+  std::vector<Bstatement*> clauses(count);
 
-  Expression_list* chan_init = new Expression_list();
-  chan_init->reserve(count);
-
-  Expression_list* is_send_init = new Expression_list();
-  is_send_init->reserve(count);
-
-  Select_clause *default_clause = NULL;
-
-  Type* runtime_chanptr_type = Runtime::chanptr_type();
-  Type* runtime_chan_type = runtime_chanptr_type->points_to();
-
+  int i = 0;
   for (Clauses::iterator p = this->clauses_.begin();
        p != this->clauses_.end();
-       ++p)
+       ++p, ++i)
     {
-      if (p->is_default())
-       {
-         default_clause = &*p;
-         --count;
-         continue;
-       }
+      int index = p->index();
+      mpz_t ival;
+      mpz_init_set_ui(ival, index);
+      Expression* index_expr = Expression::make_integer(&ival, NULL, location);
+      mpz_clear(ival);
+      cases[i].push_back(tree_to_expr(index_expr->get_tree(context)));
+
+      Bstatement* s = p->get_statements_backend(context);
+      Location gloc = (p->statements() == NULL
+                      ? p->location()
+                      : p->statements()->end_location());
+      Bstatement* g = break_label->get_goto(context, gloc);
 
-      if (p->channel()->type()->channel_type() == NULL)
-       {
-         // We should have given an error in the send or receive
-         // statement we created via lowering.
-         gcc_assert(saw_errors());
-         return context->backend()->error_statement();
-       }
-
-      Expression* c = p->channel();
-      c = Expression::make_unsafe_cast(runtime_chan_type, c, p->location());
-      chan_init->push_back(c);
-
-      is_send_init->push_back(Expression::make_boolean(p->is_send(),
-                                                      p->location()));
-    }
-
-  if (chan_init->empty())
-    {
-      gcc_assert(count == 0);
-      Bstatement* s;
-      Bstatement* ldef = break_label->get_definition(context);
-      if (default_clause != NULL)
-       {
-         // There is a default clause and no cases.  Just execute the
-         // default clause.
-         s = default_clause->get_statements_backend(context);
-       }
-      else
-       {
-         // There isn't even a default clause.  In this case select
-         // pauses forever.  Call the runtime function with nils.
-         mpz_t zval;
-         mpz_init_set_ui(zval, 0);
-         Expression* zero = Expression::make_integer(&zval, NULL, location);
-         mpz_clear(zval);
-         Expression* default_arg = Expression::make_boolean(false, location);
-         Expression* nil1 = Expression::make_nil(location);
-         Expression* nil2 = nil1->copy();
-         Expression* call = Runtime::make_call(Runtime::SELECT, location, 4,
-                                               zero, default_arg, nil1, nil2);
-         context->gogo()->lower_expression(context->function(), &call);
-         Bexpression* bcall = tree_to_expr(call->get_tree(context));
-         s = context->backend()->expression_statement(bcall);
-       }
       if (s == NULL)
-       return ldef;
-      return context->backend()->compound_statement(s, ldef);
+       clauses[i] = g;
+      else
+       clauses[i] = context->backend()->compound_statement(s, g);
     }
-  gcc_assert(count > 0);
-
-  std::vector<Bstatement*> statements;
-
-  mpz_t ival;
-  mpz_init_set_ui(ival, count);
-  Expression* ecount = Expression::make_integer(&ival, NULL, location);
-  mpz_clear(ival);
 
-  Type* chan_array_type = Type::make_array_type(runtime_chan_type, ecount);
-  Expression* chans = Expression::make_composite_literal(chan_array_type, 0,
-                                                        false, chan_init,
-                                                        location);
-  context->gogo()->lower_expression(context->function(), &chans);
-  Temporary_statement* chan_temp = Statement::make_temporary(chan_array_type,
-                                                            chans,
-                                                            location);
-  statements.push_back(tree_to_stat(chan_temp->get_tree(context)));
-
-  Type* is_send_array_type = Type::make_array_type(Type::lookup_bool_type(),
-                                                  ecount->copy());
-  Expression* is_sends = Expression::make_composite_literal(is_send_array_type,
-                                                           0, false,
-                                                           is_send_init,
-                                                           location);
-  context->gogo()->lower_expression(context->function(), &is_sends);
-  Temporary_statement* is_send_temp =
-    Statement::make_temporary(is_send_array_type, is_sends, location);
-  statements.push_back(tree_to_stat(is_send_temp->get_tree(context)));
-
-  mpz_init_set_ui(ival, 0);
-  Expression* zero = Expression::make_integer(&ival, NULL, location);
-  mpz_clear(ival);
-
-  Expression* ref = Expression::make_temporary_reference(chan_temp, location);
-  Expression* chan_arg = Expression::make_array_index(ref, zero, NULL,
-                                                     location);
-  chan_arg = Expression::make_unary(OPERATOR_AND, chan_arg, location);
-  chan_arg = Expression::make_unsafe_cast(runtime_chanptr_type, chan_arg,
-                                         location);
-
-  ref = Expression::make_temporary_reference(is_send_temp, location);
-  Expression* is_send_arg = Expression::make_array_index(ref, zero->copy(),
-                                                        NULL, location);
-  is_send_arg = Expression::make_unary(OPERATOR_AND, is_send_arg, location);
-
-  Expression* default_arg = Expression::make_boolean(default_clause != NULL,
-                                                    location);
-  Expression* call = Runtime::make_call(Runtime::SELECT, location, 4,
-                                       ecount->copy(), default_arg,
-                                       chan_arg, is_send_arg);
-  context->gogo()->lower_expression(context->function(), &call);
+  Expression* selref = Expression::make_temporary_reference(sel, location);
+  Expression* call = Runtime::make_call(Runtime::SELECTGO, location, 1,
+                                       selref);
+  context->gogo()->lower_expression(context->function(), NULL, &call);
   Bexpression* bcall = tree_to_expr(call->get_tree(context));
 
-  std::vector<std::vector<Bexpression*> > cases;
-  std::vector<Bstatement*> clauses;
-
-  cases.resize(count + (default_clause != NULL ? 1 : 0));
-  clauses.resize(count + (default_clause != NULL ? 1 : 0));
+  if (count == 0)
+    return context->backend()->expression_statement(bcall);
 
-  int index = 0;
-
-  if (default_clause != NULL)
-    {
-      this->add_clause_backend(context, location, index, 0, default_clause,
-                              break_label, &cases, &clauses);
-      ++index;
-    }
-
-  int i = 1;
-  for (Clauses::iterator p = this->clauses_.begin();
-       p != this->clauses_.end();
-       ++p)
-    {
-      if (!p->is_default())
-       {
-         this->add_clause_backend(context, location, index, i, &*p,
-                                  break_label, &cases, &clauses);
-         ++i;
-         ++index;
-       }
-    }
+  std::vector<Bstatement*> statements;
+  statements.reserve(2);
 
   Bstatement* switch_stmt = context->backend()->switch_statement(bcall,
                                                                 cases,
@@ -4309,37 +4901,15 @@ Select_clauses::get_backend(Translate_context* context,
 
   return context->backend()->statement_list(statements);
 }
-
-// Add the tree for CLAUSE to STMT_LIST.
+// Dump the AST representation for select clauses.
 
 void
-Select_clauses::add_clause_backend(
-    Translate_context* context,
-    source_location location,
-    int index,
-    int case_value,
-    Select_clause* clause,
-    Unnamed_label* bottom_label,
-    std::vector<std::vector<Bexpression*> > *cases,
-    std::vector<Bstatement*>* clauses)
+Select_clauses::dump_clauses(Ast_dump_context* ast_dump_context) const
 {
-  mpz_t ival;
-  mpz_init_set_ui(ival, case_value);
-  Expression* e = Expression::make_integer(&ival, NULL, location);
-  mpz_clear(ival);
-  (*cases)[index].push_back(tree_to_expr(e->get_tree(context)));
-
-  Bstatement* s = clause->get_statements_backend(context);
-
-  source_location gloc = (clause->statements() == NULL
-                         ? clause->location()
-                         : clause->statements()->end_location());
-  Bstatement* g = bottom_label->get_goto(context, gloc);
-                               
-  if (s == NULL)
-    (*clauses)[index] = g;
-  else
-    (*clauses)[index] = context->backend()->compound_statement(s, g);
+  for (Clauses::const_iterator p = this->clauses_.begin();
+       p != this->clauses_.end();
+       ++p)
+    p->dump_clause(ast_dump_context);
 }
 
 // Class Select_statement.
@@ -4362,31 +4932,63 @@ Select_statement::break_label()
 
 Statement*
 Select_statement::do_lower(Gogo* gogo, Named_object* function,
-                          Block* enclosing)
+                          Block* enclosing, Statement_inserter*)
 {
   if (this->is_lowered_)
     return this;
-  Block* b = new Block(enclosing, this->location());
-  this->clauses_->lower(gogo, function, b);
+
+  Location loc = this->location();
+
+  Block* b = new Block(enclosing, loc);
+
+  go_assert(this->sel_ == NULL);
+
+  mpz_t ival;
+  mpz_init_set_ui(ival, this->clauses_->size());
+  Expression* size_expr = Expression::make_integer(&ival, NULL, loc);
+  mpz_clear(ival);
+
+  Expression* call = Runtime::make_call(Runtime::NEWSELECT, loc, 1, size_expr);
+
+  this->sel_ = Statement::make_temporary(NULL, call, loc);
+  b->add_statement(this->sel_);
+
+  this->clauses_->lower(gogo, function, b, this->sel_);
   this->is_lowered_ = true;
   b->add_statement(this);
-  return Statement::make_block_statement(b, this->location());
+
+  return Statement::make_block_statement(b, loc);
 }
 
-// Return the tree for a select statement.
+// Return the backend representation for a select statement.
 
-tree
-Select_statement::do_get_tree(Translate_context* context)
+Bstatement*
+Select_statement::do_get_backend(Translate_context* context)
 {
-  Bstatement* ret = this->clauses_->get_backend(context, this->break_label(),
-                                               this->location());
-  return stat_to_tree(ret);
+  return this->clauses_->get_backend(context, this->sel_, this->break_label(),
+                                    this->location());
+}
+
+// Dump the AST representation for a select statement.
+
+void
+Select_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "select";
+  if (ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->ostream() << " {" << std::endl;
+      this->clauses_->dump_clauses(ast_dump_context);
+      ast_dump_context->ostream() << "}";
+    }
+  ast_dump_context->ostream() << std::endl;
 }
 
 // Make a select statement.
 
 Select_statement*
-Statement::make_select_statement(source_location location)
+Statement::make_select_statement(Location location)
 {
   return new Select_statement(location);
 }
@@ -4420,10 +5022,11 @@ For_statement::do_traverse(Traverse* traverse)
 // complex statements make it easier to handle garbage collection.
 
 Statement*
-For_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
+For_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
+                       Statement_inserter*)
 {
   Statement* s;
-  source_location loc = this->location();
+  Location loc = this->location();
 
   Block* b = new Block(enclosing, this->location());
   if (this->init_ != NULL)
@@ -4447,7 +5050,7 @@ For_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
                                      this->statements_->start_location());
   b->add_statement(s);
 
-  source_location end_loc = this->statements_->end_location();
+  Location end_loc = this->statements_->end_location();
 
   Unnamed_label* cont = this->continue_label_;
   if (cont != NULL)
@@ -4467,7 +5070,7 @@ For_statement::do_lower(Gogo*, Named_object*, Block* enclosing)
     {
       b->add_statement(Statement::make_unnamed_label_statement(entry));
 
-      source_location cond_loc = this->cond_->location();
+      Location cond_loc = this->cond_->location();
       Block* then_block = new Block(b, cond_loc);
       s = Statement::make_goto_unnamed_statement(top, cond_loc);
       then_block->add_statement(s);
@@ -4512,16 +5115,53 @@ void
 For_statement::set_break_continue_labels(Unnamed_label* break_label,
                                         Unnamed_label* continue_label)
 {
-  gcc_assert(this->break_label_ == NULL && this->continue_label_ == NULL);
+  go_assert(this->break_label_ == NULL && this->continue_label_ == NULL);
   this->break_label_ = break_label;
   this->continue_label_ = continue_label;
 }
 
+// Dump the AST representation for a for statement.
+
+void
+For_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+  if (this->init_ != NULL && ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->print_indent();
+      ast_dump_context->indent();
+      ast_dump_context->ostream() << "// INIT  " << std::endl;
+      ast_dump_context->dump_block(this->init_);
+      ast_dump_context->unindent();
+    }
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "for ";
+  if (this->cond_ != NULL)
+    ast_dump_context->dump_expression(this->cond_);
+
+  if (ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->ostream() << " {" << std::endl;
+      ast_dump_context->dump_block(this->statements_);
+      if (this->init_ != NULL)
+       {
+         ast_dump_context->print_indent();
+         ast_dump_context->ostream() << "// POST " << std::endl;
+         ast_dump_context->dump_block(this->post_);
+       }
+      ast_dump_context->unindent();
+
+      ast_dump_context->print_indent();
+      ast_dump_context->ostream() << "}";
+    }
+
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a for statement.
 
 For_statement*
 Statement::make_for_statement(Block* init, Expression* cond, Block* post,
-                             source_location location)
+                             Location location)
 {
   return new For_statement(init, cond, post, location);
 }
@@ -4551,12 +5191,13 @@ For_range_statement::do_traverse(Traverse* traverse)
 // statements.
 
 Statement*
-For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing)
+For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing,
+                             Statement_inserter*)
 {
   Type* range_type = this->range_->type();
   if (range_type->points_to() != NULL
       && range_type->points_to()->array_type() != NULL
-      && !range_type->points_to()->is_open_array_type())
+      && !range_type->points_to()->is_slice_type())
     range_type = range_type->points_to();
 
   Type* index_type;
@@ -4569,7 +5210,7 @@ For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing)
   else if (range_type->is_string_type())
     {
       index_type = Type::lookup_integer_type("int");
-      value_type = index_type;
+      value_type = Type::lookup_integer_type("int32");
     }
   else if (range_type->map_type() != NULL)
     {
@@ -4590,11 +5231,11 @@ For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing)
   else
     {
       this->report_error(_("range clause must have "
-                          "array, slice, setring, map, or channel type"));
+                          "array, slice, string, map, or channel type"));
       return Statement::make_error_statement(this->location());
     }
 
-  source_location loc = this->location();
+  Location loc = this->location();
   Block* temp_block = new Block(enclosing, loc);
 
   Named_object* range_object = NULL;
@@ -4606,6 +5247,7 @@ For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing)
     {
       range_temp = Statement::make_temporary(NULL, this->range_, loc);
       temp_block->add_statement(range_temp);
+      this->range_ = NULL;
     }
 
   Temporary_statement* index_temp = Statement::make_temporary(index_type,
@@ -4634,7 +5276,11 @@ For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing)
   //           original statements
   //   }
 
-  if (range_type->array_type() != NULL)
+  if (range_type->is_slice_type())
+    this->lower_range_slice(gogo, temp_block, body, range_object, range_temp,
+                           index_temp, value_temp, &init, &cond, &iter_init,
+                           &post);
+  else if (range_type->array_type() != NULL)
     this->lower_range_array(gogo, temp_block, body, range_object, range_temp,
                            index_temp, value_temp, &init, &cond, &iter_init,
                            &post);
@@ -4651,7 +5297,7 @@ For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing)
                              index_temp, value_temp, &init, &cond, &iter_init,
                              &post);
   else
-    gcc_unreachable();
+    go_unreachable();
 
   if (iter_init != NULL)
     body->add_statement(Statement::make_block_statement(iter_init, loc));
@@ -4696,7 +5342,7 @@ For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing)
 Expression*
 For_range_statement::make_range_ref(Named_object* range_object,
                                    Temporary_statement* range_temp,
-                                   source_location loc)
+                                   Location loc)
 {
   if (range_object != NULL)
     return Expression::make_var_reference(range_object, loc);
@@ -4710,17 +5356,17 @@ For_range_statement::make_range_ref(Named_object* range_object,
 Expression*
 For_range_statement::call_builtin(Gogo* gogo, const char* funcname,
                                  Expression* arg,
-                                 source_location loc)
+                                 Location loc)
 {
   Named_object* no = gogo->lookup_global(funcname);
-  gcc_assert(no != NULL && no->is_function_declaration());
+  go_assert(no != NULL && no->is_function_declaration());
   Expression* func = Expression::make_func_reference(no, NULL, loc);
   Expression_list* params = new Expression_list();
   params->push_back(arg);
   return Expression::make_call(func, params, false, loc);
 }
 
-// Lower a for range over an array or slice.
+// Lower a for range over an array.
 
 void
 For_range_statement::lower_range_array(Gogo* gogo,
@@ -4735,7 +5381,7 @@ For_range_statement::lower_range_array(Gogo* gogo,
                                       Block** piter_init,
                                       Block** ppost)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   // The loop we generate:
   //   len_temp := len(range)
@@ -4764,8 +5410,10 @@ For_range_statement::lower_range_array(Gogo* gogo,
   Expression* zexpr = Expression::make_integer(&zval, NULL, loc);
   mpz_clear(zval);
 
-  ref = Expression::make_temporary_reference(index_temp, loc);
-  Statement* s = Statement::make_assignment(ref, zexpr, loc);
+  Temporary_reference_expression* tref =
+    Expression::make_temporary_reference(index_temp, loc);
+  tref->set_is_lvalue();
+  Statement* s = Statement::make_assignment(tref, zexpr, loc);
   init->add_statement(s);
 
   *pinit = init;
@@ -4791,8 +5439,9 @@ For_range_statement::lower_range_array(Gogo* gogo,
       Expression* ref2 = Expression::make_temporary_reference(index_temp, loc);
       Expression* index = Expression::make_index(ref, ref2, NULL, loc);
 
-      ref = Expression::make_temporary_reference(value_temp, loc);
-      s = Statement::make_assignment(ref, index, loc);
+      tref = Expression::make_temporary_reference(value_temp, loc);
+      tref->set_is_lvalue();
+      s = Statement::make_assignment(tref, index, loc);
 
       iter_init->add_statement(s);
     }
@@ -4802,8 +5451,110 @@ For_range_statement::lower_range_array(Gogo* gogo,
   //   index_temp++
 
   Block* post = new Block(enclosing, loc);
+  tref = Expression::make_temporary_reference(index_temp, loc);
+  tref->set_is_lvalue();
+  s = Statement::make_inc_statement(tref);
+  post->add_statement(s);
+  *ppost = post;
+}
+
+// Lower a for range over a slice.
+
+void
+For_range_statement::lower_range_slice(Gogo* gogo,
+                                      Block* enclosing,
+                                      Block* body_block,
+                                      Named_object* range_object,
+                                      Temporary_statement* range_temp,
+                                      Temporary_statement* index_temp,
+                                      Temporary_statement* value_temp,
+                                      Block** pinit,
+                                      Expression** pcond,
+                                      Block** piter_init,
+                                      Block** ppost)
+{
+  Location loc = this->location();
+
+  // The loop we generate:
+  //   for_temp := range
+  //   len_temp := len(for_temp)
+  //   for index_temp = 0; index_temp < len_temp; index_temp++ {
+  //           value_temp = for_temp[index_temp]
+  //           index = index_temp
+  //           value = value_temp
+  //           original body
+  //   }
+  //
+  // Using for_temp means that we don't need to check bounds when
+  // fetching range_temp[index_temp].
+
+  // Set *PINIT to
+  //   range_temp := range
+  //   var len_temp int
+  //   len_temp = len(range_temp)
+  //   index_temp = 0
+
+  Block* init = new Block(enclosing, loc);
+
+  Expression* ref = this->make_range_ref(range_object, range_temp, loc);
+  Temporary_statement* for_temp = Statement::make_temporary(NULL, ref, loc);
+  init->add_statement(for_temp);
+
+  ref = Expression::make_temporary_reference(for_temp, loc);
+  Expression* len_call = this->call_builtin(gogo, "len", ref, loc);
+  Temporary_statement* len_temp = Statement::make_temporary(index_temp->type(),
+                                                           len_call, loc);
+  init->add_statement(len_temp);
+
+  mpz_t zval;
+  mpz_init_set_ui(zval, 0UL);
+  Expression* zexpr = Expression::make_integer(&zval, NULL, loc);
+  mpz_clear(zval);
+
+  Temporary_reference_expression* tref =
+    Expression::make_temporary_reference(index_temp, loc);
+  tref->set_is_lvalue();
+  Statement* s = Statement::make_assignment(tref, zexpr, loc);
+  init->add_statement(s);
+
+  *pinit = init;
+
+  // Set *PCOND to
+  //   index_temp < len_temp
+
   ref = Expression::make_temporary_reference(index_temp, loc);
-  s = Statement::make_inc_statement(ref);
+  Expression* ref2 = Expression::make_temporary_reference(len_temp, loc);
+  Expression* lt = Expression::make_binary(OPERATOR_LT, ref, ref2, loc);
+
+  *pcond = lt;
+
+  // Set *PITER_INIT to
+  //   value_temp = range[index_temp]
+
+  Block* iter_init = NULL;
+  if (value_temp != NULL)
+    {
+      iter_init = new Block(body_block, loc);
+
+      ref = Expression::make_temporary_reference(for_temp, loc);
+      Expression* ref2 = Expression::make_temporary_reference(index_temp, loc);
+      Expression* index = Expression::make_index(ref, ref2, NULL, loc);
+
+      tref = Expression::make_temporary_reference(value_temp, loc);
+      tref->set_is_lvalue();
+      s = Statement::make_assignment(tref, index, loc);
+
+      iter_init->add_statement(s);
+    }
+  *piter_init = iter_init;
+
+  // Set *PPOST to
+  //   index_temp++
+
+  Block* post = new Block(enclosing, loc);
+  tref = Expression::make_temporary_reference(index_temp, loc);
+  tref->set_is_lvalue();
+  s = Statement::make_inc_statement(tref);
   post->add_statement(s);
   *ppost = post;
 }
@@ -4823,7 +5574,7 @@ For_range_statement::lower_range_string(Gogo*,
                                        Block** piter_init,
                                        Block** ppost)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   // The loop we generate:
   //   var next_index_temp int
@@ -4851,7 +5602,9 @@ For_range_statement::lower_range_string(Gogo*,
   mpz_init_set_ui(zval, 0UL);
   Expression* zexpr = Expression::make_integer(&zval, NULL, loc);
 
-  Expression* ref = Expression::make_temporary_reference(index_temp, loc);
+  Temporary_reference_expression* ref =
+    Expression::make_temporary_reference(index_temp, loc);
+  ref->set_is_lvalue();
   Statement* s = Statement::make_assignment(ref, zexpr, loc);
 
   init->add_statement(s);
@@ -4882,14 +5635,20 @@ For_range_statement::lower_range_string(Gogo*,
   if (value_temp == NULL)
     {
       ref = Expression::make_temporary_reference(next_index_temp, loc);
+      ref->set_is_lvalue();
       s = Statement::make_assignment(ref, call, loc);
     }
   else
     {
       Expression_list* lhs = new Expression_list();
-      lhs->push_back(Expression::make_temporary_reference(next_index_temp,
-                                                         loc));
-      lhs->push_back(Expression::make_temporary_reference(value_temp, loc));
+
+      ref = Expression::make_temporary_reference(next_index_temp, loc);
+      ref->set_is_lvalue();
+      lhs->push_back(ref);
+
+      ref = Expression::make_temporary_reference(value_temp, loc);
+      ref->set_is_lvalue();
+      lhs->push_back(ref);
 
       Expression_list* rhs = new Expression_list();
       rhs->push_back(Expression::make_call_result(call, 0));
@@ -4918,7 +5677,9 @@ For_range_statement::lower_range_string(Gogo*,
 
   Block* post = new Block(enclosing, loc);
 
-  Expression* lhs = Expression::make_temporary_reference(index_temp, loc);
+  Temporary_reference_expression* lhs =
+    Expression::make_temporary_reference(index_temp, loc);
+  lhs->set_is_lvalue();
   Expression* rhs = Expression::make_temporary_reference(next_index_temp, loc);
   s = Statement::make_assignment(lhs, rhs, loc);
 
@@ -4941,7 +5702,7 @@ For_range_statement::lower_range_map(Gogo*,
                                     Block** piter_init,
                                     Block** ppost)
 {
-  source_location loc = this->location();
+  Location loc = this->location();
 
   // The runtime uses a struct to handle ranges over a map.  The
   // struct is four pointers long.  The first pointer is NULL when we
@@ -4971,7 +5732,7 @@ For_range_statement::lower_range_map(Gogo*,
   Expression* ref = Expression::make_temporary_reference(hiter, loc);
   Expression* p2 = Expression::make_unary(OPERATOR_AND, ref, loc);
   Expression* call = Runtime::make_call(Runtime::MAPITERINIT, loc, 2, p1, p2);
-  init->add_statement(Statement::make_statement(call));
+  init->add_statement(Statement::make_statement(call, true));
 
   *pinit = init;
 
@@ -5012,7 +5773,7 @@ For_range_statement::lower_range_map(Gogo*,
       Expression* p3 = Expression::make_unary(OPERATOR_AND, ref, loc);
       call = Runtime::make_call(Runtime::MAPITER2, loc, 3, p1, p2, p3);
     }
-  iter_init->add_statement(Statement::make_statement(call));
+  iter_init->add_statement(Statement::make_statement(call, true));
 
   *piter_init = iter_init;
 
@@ -5024,7 +5785,7 @@ For_range_statement::lower_range_map(Gogo*,
   ref = Expression::make_temporary_reference(hiter, loc);
   p1 = Expression::make_unary(OPERATOR_AND, ref, loc);
   call = Runtime::make_call(Runtime::MAPITERNEXT, loc, 1, p1);
-  post->add_statement(Statement::make_statement(call));
+  post->add_statement(Statement::make_statement(call, true));
 
   *ppost = post;
 }
@@ -5044,9 +5805,9 @@ For_range_statement::lower_range_channel(Gogo*,
                                         Block** piter_init,
                                         Block** ppost)
 {
-  gcc_assert(value_temp == NULL);
+  go_assert(value_temp == NULL);
 
-  source_location loc = this->location();
+  Location loc = this->location();
 
   // The loop we generate:
   //   for {
@@ -5077,10 +5838,14 @@ For_range_statement::lower_range_channel(Gogo*,
   iter_init->add_statement(ok_temp);
 
   Expression* cref = this->make_range_ref(range_object, range_temp, loc);
-  Expression* iref = Expression::make_temporary_reference(index_temp, loc);
-  Expression* oref = Expression::make_temporary_reference(ok_temp, loc);
+  Temporary_reference_expression* iref =
+    Expression::make_temporary_reference(index_temp, loc);
+  iref->set_is_lvalue();
+  Temporary_reference_expression* oref =
+    Expression::make_temporary_reference(ok_temp, loc);
+  oref->set_is_lvalue();
   Statement* s = Statement::make_tuple_receive_assignment(iref, oref, cref,
-                                                         false, loc);
+                                                         loc);
   iter_init->add_statement(s);
 
   Block* then_block = new Block(iter_init, loc);
@@ -5115,13 +5880,45 @@ For_range_statement::continue_label()
   return this->continue_label_;
 }
 
+// Dump the AST representation for a for range statement.
+
+void
+For_range_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
+{
+
+  ast_dump_context->print_indent();
+  ast_dump_context->ostream() << "for ";
+  ast_dump_context->dump_expression(this->index_var_);
+  if (this->value_var_ != NULL)
+    {
+      ast_dump_context->ostream() << ", ";
+      ast_dump_context->dump_expression(this->value_var_);
+    }
+
+  ast_dump_context->ostream() << " = range ";
+  ast_dump_context->dump_expression(this->range_);
+  if (ast_dump_context->dump_subblocks())
+    {
+      ast_dump_context->ostream() << " {" << std::endl;
+
+      ast_dump_context->indent();
+
+      ast_dump_context->dump_block(this->statements_);
+
+      ast_dump_context->unindent();
+      ast_dump_context->print_indent();
+      ast_dump_context->ostream() << "}";
+    }
+  ast_dump_context->ostream() << std::endl;
+}
+
 // Make a for statement with a range clause.
 
 For_range_statement*
 Statement::make_for_range_statement(Expression* index_var,
                                    Expression* value_var,
                                    Expression* range,
-                                   source_location location)
+                                   Location location)
 {
   return new For_range_statement(index_var, value_var, range, location);
 }