Test running compiler on a helper thread with mutator paused.

runtime/vm/compiler_test.cc

Index: runtime/vm/compiler_test.cc
diff --git a/runtime/vm/compiler_test.cc b/runtime/vm/compiler_test.cc
index aa5b8929c607cf53de5f41f2577444c4eff92bc3..c56ba377bebdbfd9c0e3ba6cb8f5375c1a686e82 100644
--- a/runtime/vm/compiler_test.cc
+++ b/runtime/vm/compiler_test.cc
@@ -9,6 +9,7 @@
 #include "vm/dart_api_impl.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
+#include "vm/thread_pool.h"
 #include "vm/unit_test.h"
 
 namespace dart {
@@ -28,7 +29,7 @@ TEST_CASE(CompileScript) {
 }
 
 
-TEST_CASE(CompileFunction) {
+static void CompileFunctionImpl() {
   const char* kScriptChars =
             "class A {\n"
             "  static foo() { return 42; }\n"
@@ -69,6 +70,70 @@ TEST_CASE(CompileFunction) {
 }
 
 
+TEST_CASE(CompileFunction) {
+  CompileFunctionImpl();
+}
+
+
+// Runs 'CompileFunctionImpl' on a helper thread.
+class CompileFunctionTask : public ThreadPool::Task {
+ public:
+  CompileFunctionTask(Isolate* isolate,
+                 Monitor* done_monitor,
+                 bool* done)
+      : isolate_(isolate),
+        done_monitor_(done_monitor),
+        done_(done) {
+  }
+
+  virtual void Run() {
+    Thread::EnterIsolateAsHelper(isolate_);
+    {
+      Thread* thread = Thread::Current();
+      StackZone stack_zone(thread);
+      HANDLESCOPE(thread);
+      CompileFunctionImpl();
+    }
+    Thread::ExitIsolateAsHelper();
+    // Tell main thread that we are done.
+    {
+      MonitorLocker ml(done_monitor_);
+      ASSERT(!*done_);
+      *done_ = true;
+      ml.Notify();
+    }
+  }
+
+ private:
+  Isolate* isolate_;
+  Monitor* done_monitor_;
+  bool* done_;
+};
+
+
+TEST_CASE(CompileFunctionOnHelperThread) {
+  Monitor done_monitor;
+  bool done = false;
+  Isolate* isolate = Thread::Current()->isolate();
+  // Flush store buffers, etc.
+  // TODO(koda): Currently, the GC only does this for the current thread, (i.e,
+  // the helper, in this test), but it should be done for all *threads*
+  // after/at safepointing.
+  Thread::PrepareForGC();
+  Dart::thread_pool()->Run(
+      new CompileFunctionTask(isolate, &done_monitor, &done));
+  {
+    // Manually wait.
+    // TODO(koda): Replace with execution of Dart and/or VM code when GC
+    // actually safepoints everything.
+    MonitorLocker ml(&done_monitor);
+    while (!done) {
+      ml.Wait();
+    }
+  }
+}
+
+
 TEST_CASE(RegenerateAllocStubs) {
   const char* kScriptChars =
             "class A {\n"