Run Crankshaft on a separate thread.

src/runtime-profiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
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 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 113 matching lines @@
     *ic_total_count = info->ic_total_count();
   }
   *percentage = *ic_total_count > 0
       ? 100 * *ic_with_type_info_count / *ic_total_count
       : 100;
 }
 
 
 void RuntimeProfiler::Optimize(JSFunction* function, const char* reason) {
   ASSERT(function->IsOptimizable());
+
+  if (FLAG_concurrent_crankshaft && !(isolate_->context() == NULL ||

[danno, 2012/05/22 10:32:19]

I don't see why this is necessary, can you explain in more detail?

[sanjoy, 2012/05/22 11:38:55]

Sometimes this function is called with the context slot set to a non-context. 
You can check this by putting ASSERT(!isolate_->context() ||
isolate_->context()->IsContext()); here and running the unit tests in debug
mode.

I'll put in a more detailed comment in the second iteration.

+                                      isolate_->context()->IsContext())) {
+    // This confuses the compiler thread
+    return;
+  }
+
   if (FLAG_trace_opt) {
     PrintF("[marking ");
     function->PrintName();
     PrintF(" 0x%" V8PRIxPTR, reinterpret_cast<intptr_t>(function->address()));
     PrintF(" for recompilation, reason: %s", reason);
     if (FLAG_type_info_threshold > 0) {
       int typeinfo, total, percentage;
       GetICCounts(function, &typeinfo, &total, &percentage);
       PrintF(", ICs with typeinfo: %d/%d (%d%%)", typeinfo, total, percentage);
     }
     PrintF("]\n");
   }
 
-  // The next call to the function will trigger optimization.
-  function->MarkForLazyRecompilation();
+  if (FLAG_concurrent_crankshaft)
+    function->CompileConcurrently();
+  else
+    function->MarkForLazyRecompilation();
 }
 
 
 void RuntimeProfiler::AttemptOnStackReplacement(JSFunction* function) {
   // See AlwaysFullCompiler (in compiler.cc) comment on why we need
   // Debug::has_break_points().
   ASSERT(function->IsMarkedForLazyRecompilation());
   if (!FLAG_use_osr ||
       isolate_->DebuggerHasBreakPoints() ||
       function->IsBuiltin()) {
@@ skipping 305 matching lines @@
 
 bool RuntimeProfilerRateLimiter::SuspendIfNecessary() {
   if (!RuntimeProfiler::IsSomeIsolateInJS()) {
     return RuntimeProfiler::WaitForSomeIsolateToEnterJS();
   }
   return false;
 }
 
 
 } }  // namespace v8::internal