Revert "Revert "Use Kernel frontend from run_vm_tests.""

runtime/vm/unit_test.cc

Index: runtime/vm/unit_test.cc
diff --git a/runtime/vm/unit_test.cc b/runtime/vm/unit_test.cc
index 147d0eb73afce0358c8f37b00e447133a44d2de2..ebe84ded532ee3b5b65d68aec825d7e37c997ffc 100644
--- a/runtime/vm/unit_test.cc
+++ b/runtime/vm/unit_test.cc
@@ -28,6 +28,8 @@ using dart::bin::DartUtils;
 
 namespace dart {
 
+DECLARE_FLAG(bool, use_dart_frontend);
+
 TestCaseBase* TestCaseBase::first_ = NULL;
 TestCaseBase* TestCaseBase::tail_ = NULL;
 
@@ -258,11 +260,10 @@ static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
   }
 }
 
-
-Dart_Handle TestCase::LoadTestScript(const char* script,
-                                     Dart_NativeEntryResolver resolver,
-                                     const char* lib_url,
-                                     bool finalize_classes) {
+static Dart_Handle LoadTestScriptWithVMParser(const char* script,
+                                              Dart_NativeEntryResolver resolver,
+                                              const char* lib_url,
+                                              bool finalize_classes) {
   Dart_Handle url = NewString(lib_url);
   Dart_Handle source = NewString(script);
   Dart_Handle result = Dart_SetLibraryTagHandler(LibraryTagHandler);
@@ -278,6 +279,49 @@ Dart_Handle TestCase::LoadTestScript(const char* script,
   return lib;
 }
 
+Dart_Handle TestCase::LoadTestScript(const char* script,
+                                     Dart_NativeEntryResolver resolver,
+                                     const char* lib_url,
+                                     bool finalize_classes) {
+  if (!FLAG_use_dart_frontend) {
+    return LoadTestScriptWithVMParser(script, resolver, lib_url,
+                                      finalize_classes);
+  }
+
+  Zone* zone = Thread::Current()->zone();
+  char* filename = OS::SCreate(zone, "file:///%s", lib_url);
+  // clang-format off
+  Dart_SourceFile sourcefiles[] = {
+    {
+      filename, script,
+    },
+    {
+      "file:///.packages", "untitled:/"
+    }};
+  // clang-format on
+
+  int sourcefiles_count = sizeof(sourcefiles) / sizeof(Dart_SourceFile);
+  Dart_KernelCompilationResult compilation_result =
+      Dart_CompileSourcesToKernel(filename, sourcefiles_count, sourcefiles);
+
+  if (compilation_result.status != Dart_KernelCompilationStatus_Ok) {
+    return Dart_NewApiError(OS::SCreate(Thread::Current()->zone(),
+                                        "Compilation failed %s",
+                                        compilation_result.error));
+  }
+  const uint8_t* kernel_file = compilation_result.kernel;
+  intptr_t kernel_length = compilation_result.kernel_size;
+  if (kernel_file == NULL) {
+    return Dart_NewApiError(OS::SCreate(
+        Thread::Current()->zone(), "front end generated a NULL kernel file"));
+  }
+  void* kernel_program = Dart_ReadKernelBinary(kernel_file, kernel_length);
+  if (kernel_program == NULL) {
+    return Dart_NewApiError(OS::SCreate(
+        Thread::Current()->zone(), "Failed to read generated kernel binary"));
+  }
+  return Dart_LoadKernel(kernel_program);
+}
 
 #ifndef PRODUCT