Run Crankshaft on a separate thread.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index a42f90cc7d98d2f5092b9af7322379160f4c2f07..e19df2ca6239eb21de2812c6459ac5aabbbe6b07 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -8095,12 +8095,9 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_LazyCompile) {
   return function->code();
 }
 
-
-RUNTIME_FUNCTION(MaybeObject*, Runtime_LazyRecompile) {
-  HandleScope scope(isolate);
-  ASSERT(args.length() == 1);
-  Handle<JSFunction> function = args.at<JSFunction>(0);
-
+// Compile function using CrankShaft and return a pointer to its code.
+MaybeObject *CompileJSFunction(Isolate *isolate,
+                               Handle<JSFunction> function) {
   // If the function is not compiled ignore the lazy
   // recompilation. This can happen if the debugger is activated and
   // the function is returned to the not compiled state.
@@ -8139,6 +8136,13 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_LazyRecompile) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_LazyRecompile) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 1);
+  return CompileJSFunction(isolate, args.at<JSFunction>(0));
+}
+
+
 class ActivationsFinder : public ThreadVisitor {
  public:
   explicit ActivationsFinder(JSFunction* function)
@@ -8329,6 +8333,9 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetOptimizationStatus) {
   if (!V8::UseCrankshaft()) {
     return Smi::FromInt(4);  // 4 == "never".
   }
+  if (FLAG_concurrent_crankshaft) {
+    return Smi::FromInt(5);  // 5 == "concurrent"
+  }
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
   if (FLAG_always_opt) {
     // We may have always opt, but that is more best-effort than a real
@@ -9027,6 +9034,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_StackGuard) {
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_Interrupt) {
   ASSERT(args.length() == 0);
+  ASSERT(!FLAG_concurrent_crankshaft ||
+         isolate->thread_manager()->IsLockedByCurrentThread());
   return Execution::HandleStackGuardInterrupt(isolate);
 }