Parallel recompilation: remove interrupt for code generation.

src/optimizing-compiler-thread.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
 //       notice, this list of conditions and the following disclaimer.
 //     * 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 50 matching lines @@
         time_spent_total_ = OS::Ticks() - epoch;
       }
       return;
     }
 
     int64_t compiling_start = 0;
     if (FLAG_trace_parallel_recompilation) compiling_start = OS::Ticks();
 
     CompileNext();
 
-    if (!FLAG_manual_parallel_recompilation) {
-      isolate_->stack_guard()->RequestCodeReadyEvent();
-    } else {
-      // In manual mode, do not trigger a code ready event.
-      // Instead, wait for the optimized functions to be installed manually.
-      output_queue_semaphore_->Signal();
-    }
-
     if (FLAG_trace_parallel_recompilation) {
       time_spent_compiling_ += OS::Ticks() - compiling_start;
     }
   }
 }
 
 
 void OptimizingCompilerThread::CompileNext() {
   Heap::RelocationLock relocation_lock(isolate_->heap());
   OptimizingCompiler* optimizing_compiler = NULL;
   input_queue_.Dequeue(&optimizing_compiler);
   Barrier_AtomicIncrement(&queue_length_, static_cast<Atomic32>(-1));
 
-  // Function may have been optimized meanwhile by OSR.
-  if (FLAG_use_osr &&
-      optimizing_compiler->info()->closure()->IsOptimized()) {
-    return;
-  }
+  ASSERT(optimizing_compiler->info()->closure()->IsInRecompileQueue());
 
   OptimizingCompiler::Status status = optimizing_compiler->OptimizeGraph();
   ASSERT(status != OptimizingCompiler::FAILED);
   // Prevent an unused-variable error in release mode.
   USE(status);
 
   output_queue_.Enqueue(optimizing_compiler);
+
+  // After putting the finished function onto the install queue but before

[Jakob Kummerow, 2013/03/12 15:19:30]

This comment is misleading. Maybe something like:
The execution thread can call InstallOptimizedFunctions() at any time, including
right now, but that function doesn't do anything with the optimizing_compiler we
just enqueued unless its closure is marked for installing recompiled code.

[Yang, 2013/03/12 18:03:38]

Done.

+  // marking via builtin, OptimizeNow in the execution thread may have
+  // already called InstallOptimizedFunctions.
+
+  ASSERT(optimizing_compiler->info()->closure()->IsInRecompileQueue());
+  // Mark function to generate and install optimized code.  We assume this
+  // write to be atomic.
+  optimizing_compiler->info()->closure()->MarkForInstallingRecompiledCode();
 }
 
 
 void OptimizingCompilerThread::Stop() {
+  ASSERT(!IsOptimizerThread());
   Release_Store(&stop_thread_, static_cast<AtomicWord>(true));
   input_queue_semaphore_->Signal();
   stop_semaphore_->Wait();
 
   if (FLAG_parallel_recompilation_delay != 0) {
     // Execution ended before we managed to compile and install the remaining
     // functions in the queue.  We still want to do that for debugging though.
     // At this point the optimizing thread already stopped, so we finish
     // processing the queue in the main thread.
     InstallOptimizedFunctions();
     // Barrier when loading queue length is not necessary since the write
     // happens in CompileNext on the same thread.
     while (NoBarrier_Load(&queue_length_) > 0) {
       CompileNext();
       InstallOptimizedFunctions();
     }
   }
 
   if (FLAG_trace_parallel_recompilation) {
     double compile_time = static_cast<double>(time_spent_compiling_);
     double total_time = static_cast<double>(time_spent_total_);
     double percentage = (compile_time * 100) / total_time;
     PrintF("  ** Compiler thread did %.2f%% useful work\n", percentage);
   }
 }
 
 
 void OptimizingCompilerThread::InstallOptimizedFunctions() {
+  ASSERT(!IsOptimizerThread());
   HandleScope handle_scope(isolate_);
   int functions_installed = 0;
   while (!output_queue_.IsEmpty()) {
-    if (FLAG_manual_parallel_recompilation) {
-      output_queue_semaphore_->Wait();
+    OptimizingCompiler* compiler = *output_queue_.Peek();
+
+    if (compiler->info()->closure()->IsInRecompileQueue()) {
+      // A function may be queued for installing, but not been marked as such
+      // just yet, but still marked as in queue.  We continue with the output
+      // queue the next time.  Otherwise we may encounter a race condition.
+      break;
     }
-    OptimizingCompiler* compiler = NULL;
     output_queue_.Dequeue(&compiler);
+
+#ifdef DEBUG
+    // Create new closure handle since the deferred handle is about to die.
+    Handle<JSFunction> closure(*compiler->info()->closure());
+#endif  // DEBUG
+
     Compiler::InstallOptimizedCode(compiler);
+    // Assert that the marker builtin has been replaced by actual code.
+    ASSERT(!closure->IsInRecompileQueue());
     functions_installed++;
   }
-  if (FLAG_trace_parallel_recompilation && functions_installed != 0) {
-    PrintF("  ** Installed %d function(s).\n", functions_installed);
-  }
-}
-
-
-Handle<SharedFunctionInfo>
-    OptimizingCompilerThread::InstallNextOptimizedFunction() {
-  ASSERT(FLAG_manual_parallel_recompilation ||
-         FLAG_parallel_recompilation_delay != 0);
-  output_queue_semaphore_->Wait();
-  OptimizingCompiler* compiler = NULL;
-  output_queue_.Dequeue(&compiler);
-  // Copy a handle from deferred handle scope to the normal handle scope.
-  Handle<SharedFunctionInfo> shared(*compiler->info()->shared_info());
-  Compiler::InstallOptimizedCode(compiler);
-  return shared;
 }
 
 
 void OptimizingCompilerThread::QueueForOptimization(
     OptimizingCompiler* optimizing_compiler) {
   ASSERT(IsQueueAvailable());
+  ASSERT(!IsOptimizerThread());
   Barrier_AtomicIncrement(&queue_length_, static_cast<Atomic32>(1));
   input_queue_.Enqueue(optimizing_compiler);
   input_queue_semaphore_->Signal();
 }
 
+
 #ifdef DEBUG
 bool OptimizingCompilerThread::IsOptimizerThread() {
   if (!FLAG_parallel_recompilation) return false;
   return ThreadId::Current().ToInteger() == thread_id_;
 }
 #endif
 
 
 } }  // namespace v8::internal