Use backend interface for labels and goto statements.

	* go-gcc.c (class Blabel): Define.
	(Gcc_backend::make_expression): New function.
	(get_identifier_from_string): New function.
	(Gcc_backend::label): New function.
	(Gcc_backend::label_definition_statement): New function.
	(Gcc_backend::goto_statement): New function.
	(Gcc_backend::label_address): New function.
	(expression_to_tree): New function.
	* Make-lang.in (go/expressions.o): Depend on
	go/gofrontend/backend.h.
	(go/gogo.o): Likewise.

From-SVN: r171968

6 files changed, 159 insertions, 95 deletions

diff --git a/gcc/go/gofrontend/backend.h b/gcc/go/gofrontend/backend.h
index 959fc78..814263e 100644
--- a/gcc/go/gofrontend/backend.h
+++ b/gcc/go/gofrontend/backend.h
@@ -27,6 +27,9 @@ class Bstatement;
 // The backend representation of a function definition.
 class Bfunction;
 
+// The backend representation of a label.
+class Blabel;
+
 // A list of backend types.
 typedef std::vector<Btype*> Btypes;
 
@@ -114,6 +117,30 @@ class Backend
   virtual Bstatement*
   return_statement(Bfunction*, const std::vector<Bexpression*>&,
 		   source_location) = 0;
+
+  // Labels.
+  
+  // Create a new label.  NAME will be empty if this is a label
+  // created by the frontend for a loop construct.  The location is
+  // where the the label is defined.
+  virtual Blabel*
+  label(Bfunction*, const std::string& name, source_location) = 0;
+
+  // Create a statement which defines a label.  This statement will be
+  // put into the codestream at the point where the label should be
+  // defined.
+  virtual Bstatement*
+  label_definition_statement(Blabel*) = 0;
+
+  // Create a goto statement to a label.
+  virtual Bstatement*
+  goto_statement(Blabel*, source_location) = 0;
+
+  // Create an expression for the address of a label.  This is used to
+  // get the return address of a deferred function which may call
+  // recover.
+  virtual Bexpression*
+  label_address(Blabel*, source_location) = 0;
 };
 
 // The backend interface has to define this function.
@@ -125,6 +152,7 @@ extern Backend* go_get_backend();
 
 extern Bexpression* tree_to_expr(tree);
 extern Bfunction* tree_to_function(tree);
+extern tree expression_to_tree(Bexpression*);
 extern tree statement_to_tree(Bstatement*);
 
 #endif // !defined(GO_BACKEND_H)
diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc
index a0cfcfc..afd2191 100644
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -33,6 +33,7 @@ extern "C"
 #include "import.h"
 #include "statements.h"
 #include "lex.h"
+#include "backend.h"
 #include "expressions.h"
 
 // Class Expression.
@@ -12595,8 +12596,11 @@ class Label_addr_expression : public Expression
   { return new Label_addr_expression(this->label_, this->location()); }
 
   tree
-  do_get_tree(Translate_context*)
-  { return this->label_->get_addr(this->location()); }
+  do_get_tree(Translate_context* context)
+  {
+    return expression_to_tree(this->label_->get_addr(context,
+						     this->location()));
+  }
 
  private:
   // The label whose address we are taking.
diff --git a/gcc/go/gofrontend/gogo-tree.cc b/gcc/go/gofrontend/gogo-tree.cc
index bd5945b..53e43c7 100644
--- a/gcc/go/gofrontend/gogo-tree.cc
+++ b/gcc/go/gofrontend/gogo-tree.cc
@@ -1915,62 +1915,6 @@ Block::get_tree(Translate_context* context)
   return bind;
 }
 
-// Get the LABEL_DECL for a label.
-
-tree
-Label::get_decl()
-{
-  if (this->decl_ == NULL)
-    {
-      tree id = get_identifier_from_string(this->name_);
-      this->decl_ = build_decl(this->location_, LABEL_DECL, id, void_type_node);
-      DECL_CONTEXT(this->decl_) = current_function_decl;
-    }
-  return this->decl_;
-}
-
-// Return an expression for the address of this label.
-
-tree
-Label::get_addr(source_location location)
-{
-  tree decl = this->get_decl();
-  TREE_USED(decl) = 1;
-  TREE_ADDRESSABLE(decl) = 1;
-  return fold_convert_loc(location, ptr_type_node,
-			  build_fold_addr_expr_loc(location, decl));
-}
-
-// Get the LABEL_DECL for an unnamed label.
-
-tree
-Unnamed_label::get_decl()
-{
-  if (this->decl_ == NULL)
-    this->decl_ = create_artificial_label(this->location_);
-  return this->decl_;
-}
-
-// Get the LABEL_EXPR for an unnamed label.
-
-tree
-Unnamed_label::get_definition()
-{
-  tree t = build1(LABEL_EXPR, void_type_node, this->get_decl());
-  SET_EXPR_LOCATION(t, this->location_);
-  return t;
-}
-
-// Return a goto to this label.
-
-tree
-Unnamed_label::get_goto(source_location location)
-{
-  tree t = build1(GOTO_EXPR, void_type_node, this->get_decl());
-  SET_EXPR_LOCATION(t, location);
-  return t;
-}
-
 // Return the integer type to use for a size.
 
 GO_EXTERN_C
diff --git a/gcc/go/gofrontend/gogo.cc b/gcc/go/gofrontend/gogo.cc
index 5b3ac8c..31549ac 100644
--- a/gcc/go/gofrontend/gogo.cc
+++ b/gcc/go/gofrontend/gogo.cc
@@ -15,6 +15,7 @@
 #include "dataflow.h"
 #include "import.h"
 #include "export.h"
+#include "backend.h"
 #include "gogo.h"
 
 // Class Gogo.
@@ -4430,6 +4431,69 @@ Bindings::traverse(Traverse* traverse, bool is_global)
   return TRAVERSE_CONTINUE;
 }
 
+// Class Label.
+
+// Get the backend representation for a label.
+
+Blabel*
+Label::get_backend_label(Translate_context* context)
+{
+  if (this->blabel_ == NULL)
+    {
+      Function* function = context->function()->func_value();
+      tree fndecl = function->get_decl();
+      Bfunction* bfunction = tree_to_function(fndecl);
+      this->blabel_ = context->backend()->label(bfunction, this->name_,
+						this->location_);
+    }
+  return this->blabel_;
+}
+
+// Return an expression for the address of this label.
+
+Bexpression*
+Label::get_addr(Translate_context* context, source_location location)
+{
+  Blabel* label = this->get_backend_label(context);
+  return context->backend()->label_address(label, location);
+}
+
+// Class Unnamed_label.
+
+// Get the backend representation for an unnamed label.
+
+Blabel*
+Unnamed_label::get_blabel(Translate_context* context)
+{
+  if (this->blabel_ == NULL)
+    {
+      Function* function = context->function()->func_value();
+      tree fndecl = function->get_decl();
+      Bfunction* bfunction = tree_to_function(fndecl);
+      this->blabel_ = context->backend()->label(bfunction, "",
+						this->location_);
+    }
+  return this->blabel_;
+}
+
+// Return a statement which defines this unnamed label.
+
+Bstatement*
+Unnamed_label::get_definition(Translate_context* context)
+{
+  Blabel* blabel = this->get_blabel(context);
+  return context->backend()->label_definition_statement(blabel);
+}
+
+// Return a goto statement to this unnamed label.
+
+Bstatement*
+Unnamed_label::get_goto(Translate_context* context, source_location location)
+{
+  Blabel* blabel = this->get_blabel(context);
+  return context->backend()->goto_statement(blabel, location);
+}
+
 // Class Package.
 
 Package::Package(const std::string& name, const std::string& unique_prefix,
diff --git a/gcc/go/gofrontend/gogo.h b/gcc/go/gofrontend/gogo.h
index 87e2da6..cf126cd 100644
--- a/gcc/go/gofrontend/gogo.h
+++ b/gcc/go/gofrontend/gogo.h
@@ -40,6 +40,9 @@ class Translate_context;
 class Backend;
 class Export;
 class Import;
+class Bexpression;
+class Bstatement;
+class Blabel;
 
 // This file declares the basic classes used to hold the internal
 // representation of Go which is built by the parser.
@@ -2115,7 +2118,7 @@ class Label
 {
  public:
   Label(const std::string& name)
-    : name_(name), location_(0), is_used_(false), decl_(NULL)
+    : name_(name), location_(0), is_used_(false), blabel_(NULL)
   { }
 
   // Return the label's name.
@@ -2151,13 +2154,15 @@ class Label
     this->location_ = location;
   }
 
-  // Return the LABEL_DECL for this decl.
-  tree
-  get_decl();
+  // Return the backend representation for this label.
+  Blabel*
+  get_backend_label(Translate_context*);
 
-  // Return an expression for the address of this label.
-  tree
-  get_addr(source_location location);
+  // Return an expression for the address of this label.  This is used
+  // to get the return address of a deferred function to see whether
+  // the function may call recover.
+  Bexpression*
+  get_addr(Translate_context*, source_location location);
 
  private:
   // The name of the label.
@@ -2167,8 +2172,8 @@ class Label
   source_location location_;
   // Whether the label has been used.
   bool is_used_;
-  // The LABEL_DECL.
-  tree decl_;
+  // The backend representation.
+  Blabel* blabel_;
 };
 
 // An unnamed label.  These are used when lowering loops.
@@ -2177,7 +2182,7 @@ class Unnamed_label
 {
  public:
   Unnamed_label(source_location location)
-    : location_(location), decl_(NULL)
+    : location_(location), blabel_(NULL)
   { }
 
   // Get the location where the label is defined.
@@ -2191,22 +2196,22 @@ class Unnamed_label
   { this->location_ = location; }
 
   // Return a statement which defines this label.
-  tree
-  get_definition();
+  Bstatement*
+  get_definition(Translate_context*);
 
   // Return a goto to this label from LOCATION.
-  tree
-  get_goto(source_location location);
+  Bstatement*
+  get_goto(Translate_context*, source_location location);
 
  private:
-  // Return the LABEL_DECL to use with GOTO_EXPR.
-  tree
-  get_decl();
+  // Return the backend representation.
+  Blabel*
+  get_blabel(Translate_context*);
 
   // The location where the label is defined.
   source_location location_;
-  // The LABEL_DECL.
-  tree decl_;
+  // The backend representation of this label.
+  Blabel* blabel_;
 };
 
 // An imported package.
diff --git a/gcc/go/gofrontend/statements.cc b/gcc/go/gofrontend/statements.cc
index 3783fb8..854b329 100644
--- a/gcc/go/gofrontend/statements.cc
+++ b/gcc/go/gofrontend/statements.cc
@@ -2619,8 +2619,11 @@ class Bc_statement : public Statement
   { return false; }
 
   tree
-  do_get_tree(Translate_context*)
-  { return this->label_->get_goto(this->location()); }
+  do_get_tree(Translate_context* context)
+  {
+    return statement_to_tree(this->label_->get_goto(context,
+						    this->location()));
+  }
 
  private:
   // The label that this branches to.
@@ -2692,9 +2695,12 @@ Goto_statement::do_check_types(Gogo*)
 // Return the tree for the goto statement.
 
 tree
-Goto_statement::do_get_tree(Translate_context*)
+Goto_statement::do_get_tree(Translate_context* context)
 {
-  return this->build_stmt_1(GOTO_EXPR, this->label_->get_decl());
+  Blabel* blabel = this->label_->get_backend_label(context);
+  Bstatement* statement = context->backend()->goto_statement(blabel,
+							     this->location());
+  return statement_to_tree(statement);
 }
 
 // Make a goto statement.
@@ -2725,8 +2731,11 @@ class Goto_unnamed_statement : public Statement
   { return false; }
 
   tree
-  do_get_tree(Translate_context*)
-  { return this->label_->get_goto(this->location()); }
+  do_get_tree(Translate_context* context)
+  {
+    return statement_to_tree(this->label_->get_goto(context,
+						    this->location()));
+  }
 
  private:
   Unnamed_label* label_;
@@ -2754,9 +2763,12 @@ Label_statement::do_traverse(Traverse*)
 // Return a tree defining this label.
 
 tree
-Label_statement::do_get_tree(Translate_context*)
+Label_statement::do_get_tree(Translate_context* context)
 {
-  return this->build_stmt_1(LABEL_EXPR, this->label_->get_decl());
+  Blabel* blabel = this->label_->get_backend_label(context);
+  Bstatement* statement;
+  statement = context->backend()->label_definition_statement(blabel);
+  return statement_to_tree(statement);
 }
 
 // Make a label statement.
@@ -2783,8 +2795,8 @@ class Unnamed_label_statement : public Statement
   { return TRAVERSE_CONTINUE; }
 
   tree
-  do_get_tree(Translate_context*)
-  { return this->label_->get_definition(); }
+  do_get_tree(Translate_context* context)
+  { return statement_to_tree(this->label_->get_definition(context)); }
 
  private:
   // The label.
@@ -3134,7 +3146,10 @@ Case_clauses::Case_clause::get_constant_tree(Translate_context* context,
     }
 
   if (!this->is_fallthrough_)
-    append_to_statement_list(break_label->get_goto(this->location_), stmt_list);
+    {
+      Bstatement* g = break_label->get_goto(context, this->location_);
+      append_to_statement_list(statement_to_tree(g), stmt_list);
+    }
 }
 
 // Class Case_clauses.
@@ -3387,7 +3402,8 @@ Constant_switch_statement::do_get_tree(Translate_context* context)
   SET_EXPR_LOCATION(s, this->location());
   append_to_statement_list(s, &stmt_list);
 
-  append_to_statement_list(break_label->get_definition(), &stmt_list);
+  Bstatement* ldef = break_label->get_definition(context);
+  append_to_statement_list(statement_to_tree(ldef), &stmt_list);
 
   return stmt_list;
 }
@@ -4245,7 +4261,8 @@ Select_clauses::get_tree(Translate_context* context,
       tree stmt_list = NULL_TREE;
       append_to_statement_list(default_clause->get_statements_tree(context),
 			       &stmt_list);
-      append_to_statement_list(break_label->get_definition(), &stmt_list);
+      Bstatement* ldef = break_label->get_definition(context);
+      append_to_statement_list(statement_to_tree(ldef), &stmt_list);
       return stmt_list;
     }
 
@@ -4336,7 +4353,8 @@ Select_clauses::get_tree(Translate_context* context,
 	}
     }
 
-  append_to_statement_list(break_label->get_definition(), &stmt_list);
+  Bstatement* ldef = break_label->get_definition(context);
+  append_to_statement_list(statement_to_tree(ldef), &stmt_list);
 
   tree switch_stmt = build3(SWITCH_EXPR, sizetype, call, stmt_list, NULL_TREE);
   SET_EXPR_LOCATION(switch_stmt, location);
@@ -4358,10 +4376,11 @@ Select_clauses::add_clause_tree(Translate_context* context, int case_index,
 				  NULL_TREE, label),
 			   stmt_list);
   append_to_statement_list(clause->get_statements_tree(context), stmt_list);
-  tree g = bottom_label->get_goto(clause->statements() == NULL
-				  ? clause->location()
-				  : clause->statements()->end_location());
-  append_to_statement_list(g, stmt_list);
+  source_location gloc = (clause->statements() == NULL
+			  ? clause->location()
+			  : clause->statements()->end_location());
+  Bstatement* g = bottom_label->get_goto(context, gloc);
+  append_to_statement_list(statement_to_tree(g), stmt_list);
 }
 
 // Class Select_statement.