[Interpreter] Implement do expressions.

test/cctest/interpreter/test-interpreter.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/execution.h"
 #include "src/handles.h"
 #include "src/interpreter/bytecode-array-builder.h"
 #include "src/interpreter/interpreter.h"
@@ skipping 3807 matching lines @@
     Handle<Object> arg = handle(Smi::FromInt(i), isolate);
     Handle<Object> return_value = callable(arg).ToHandleChecked();
     int expected = kBaseValue + i * (i + 1) / 2;
     Handle<Smi> actual = Handle<Smi>::cast(return_value);
     CHECK_EQ(actual->value(), expected);
   }
 }
 
 // TODO(oth): Test for..in with wide registers.
 
+TEST(InterpreterDoExpression) {
+  bool old_flag = FLAG_harmony_do_expressions;
+  FLAG_harmony_do_expressions = true;
+
+  HandleAndZoneScope handles;
+  i::Isolate* isolate = handles.main_isolate();
+  Factory* factory = isolate->factory();
+
+  std::pair<const char*, Handle<Object>> do_expr[] = {
+      {"var a = do {}; return a;", factory->undefined_value()},
+      {"var a = do { var x = 100; }; return a;", factory->undefined_value()},
+      {"var a = do { var x = 100; }; return a;", factory->undefined_value()},
+      {"var a = do { var x = 100; x++; }; return a;",
+       handle(Smi::FromInt(100), isolate)},
+      {"var i = 0; for (; i < 5;) { i = do { if (i == 3) { break; }; i + 1; }};"
+       "return i;",
+       handle(Smi::FromInt(3), isolate)},
+  };
+
+  for (size_t i = 0; i < arraysize(do_expr); i++) {
+    std::string source(InterpreterTester::SourceForBody(do_expr[i].first));
+    InterpreterTester tester(handles.main_isolate(), source.c_str());
+    auto callable = tester.GetCallable<>();
+
+    Handle<i::Object> return_value = callable().ToHandleChecked();
+    CHECK(return_value->SameValue(*do_expr[i].second));
+  }
+
+  FLAG_harmony_do_expressions = old_flag;
+}
+
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8