VM: [Kernel] Don't emit ReturnInstr that are not connected to the graph.

runtime/vm/kernel_to_il.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <map>
 #include <set>
 #include <string>
 
 #include "vm/kernel_to_il.h"
 
@@ skipping 4898 matching lines @@
 void FlowGraphBuilder::VisitEmptyStatement(EmptyStatement* node) {
   fragment_ = Fragment();
 }
 
 
 void FlowGraphBuilder::VisitBlock(Block* node) {
   Fragment instructions;
 
   instructions += EnterScope(node);
   List<Statement>& statements = node->statements();
-  for (intptr_t i = 0; i < statements.length(); ++i) {
+  for (intptr_t i = 0; (i < statements.length()) && instructions.is_open();
+       ++i) {
     instructions += TranslateStatement(statements[i]);
   }
   instructions += ExitScope(node);
 
   fragment_ = instructions;
 }
 
 
 void FlowGraphBuilder::VisitReturnStatement(ReturnStatement* node) {
   bool inside_try_finally = try_finally_block_ != NULL;
 
   Fragment instructions = node->expression() == NULL
                               ? NullConstant()
                               : TranslateExpression(node->expression());
-  if (inside_try_finally) {
-    ASSERT(scopes_->finally_return_variable != NULL);
-    instructions += StoreLocal(scopes_->finally_return_variable);
-    instructions += Drop();
-    instructions += TranslateFinallyFinalizers(NULL, -1);
-    if (instructions.is_open()) {
-      instructions += LoadLocal(scopes_->finally_return_variable);
+  if (instructions.is_open()) {
+    if (inside_try_finally) {
+      ASSERT(scopes_->finally_return_variable != NULL);
+      instructions += StoreLocal(scopes_->finally_return_variable);
+      instructions += Drop();
+      instructions += TranslateFinallyFinalizers(NULL, -1);
+      if (instructions.is_open()) {
+        instructions += LoadLocal(scopes_->finally_return_variable);
+        instructions += Return();
+      }
+    } else {
       instructions += Return();
     }
-  } else {
-    instructions += Return();
   }
   fragment_ = instructions;
 }
 
 
 void FlowGraphBuilder::VisitExpressionStatement(ExpressionStatement* node) {
   Fragment instructions = TranslateExpression(node->expression());
   instructions += Drop();
   fragment_ = instructions;
 }
@@ skipping 847 matching lines @@
   instructions += LoadLocal(parsed_function_->current_context_var());
   instructions += StoreInstanceField(Closure::context_offset());
 
   return instructions;
 }
 
 
 }  // namespace kernel
 }  // namespace dart
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)