Make ICData changes thread safe (first compute array, then set it). Install code in the main thread…

runtime/vm/compiler.h

Index: runtime/vm/compiler.h
diff --git a/runtime/vm/compiler.h b/runtime/vm/compiler.h
index 28732f4ccbfe27b6305f0343e705594930722e67..70c436f846de029977616079320fc3d504c30de5 100644
--- a/runtime/vm/compiler.h
+++ b/runtime/vm/compiler.h
@@ -14,6 +14,7 @@ namespace dart {
 
 // Forward declarations.
 class Class;
+class Code;
 class Function;
 class Library;
 class ParsedFunction;
@@ -23,6 +24,8 @@ class SequenceNode;
 
 class Compiler : public AllStatic {
  public:
+  static const intptr_t kNoOSRDeoptId = Thread::kNoDeoptId;
+
   // Extracts top level entities from the script and populates
   // the class dictionary of the library.
   //
@@ -47,10 +50,13 @@ class Compiler : public AllStatic {
   // Generates optimized code for function.
   //
   // Returns Error::null() if there is no compilation error.
+  // If 'result_code' is not NULL, then the generated code is returned but
+  // not installed.
   static RawError* CompileOptimizedFunction(
       Thread* thread,
       const Function& function,
-      intptr_t osr_id = Thread::kNoDeoptId);
+      intptr_t osr_id = kNoOSRDeoptId,
+      Code* result_code = NULL);
 
   // Generates code for given parsed function (without parsing it again) and
   // sets its code field.
@@ -104,26 +110,39 @@ class Compiler : public AllStatic {
 // Class to run optimizing compilation in a background thread.
 // Current implementation: one task per isolate, it dies with the owning
 // isolate.
+// No OSR compilation in the background compiler.
 class BackgroundCompiler : public ThreadPool::Task {
  public:
   static void EnsureInit(Thread* thread);
 
   static void Stop(BackgroundCompiler* task);
 
+  // Call to optimize a function in the background, enters the function in the
+  // compilation queue.
   void CompileOptimized(const Function& function);
 
+  // Call to activate/install optimized code (must occur in the mutator thread).
+  void InstallGeneratedCode();
+
   // Access to queue length is guarded with queue_monitor_;
-  intptr_t queue_length() const { return queue_length_; }
-  void set_queue_length(intptr_t value) { queue_length_ = value; }
+  intptr_t function_queue_length() const { return function_queue_length_; }
+  void set_function_queue_length(intptr_t value) {
+    function_queue_length_ = value;
+  }
 
  private:
   explicit BackgroundCompiler(Isolate* isolate);
 
+  GrowableObjectArray* FunctionsQueue() const;
+  GrowableObjectArray* CodesQueue() const;
+
   virtual void Run();
 
-  void Add(const Function& f);
-  RawFunction* RemoveOrNull();
-  RawFunction* LastOrNull() const;
+  void AddFunction(const Function& f);
+  RawFunction* RemoveFunctionOrNull();
+  RawFunction* LastFunctionOrNull() const;
+
+  void AddCode(const Code& c);
 
   Isolate* isolate_;
   bool running_;       // While true, will try to read queue and compile.
@@ -131,7 +150,8 @@ class BackgroundCompiler : public ThreadPool::Task {
   Monitor* queue_monitor_;  // Controls access to the queue.
   Monitor* done_monitor_;   // Notify/wait that the thread is done.
 
-  intptr_t queue_length_;  // Lightweight access to length of compiler queue.
+  // Lightweight access to length of compiler queue.
+  intptr_t function_queue_length_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BackgroundCompiler);
 };