Introduce concurrent on-stack replacement.

src/compiler.h

 // 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 290 matching lines @@
   void AbortDueToDependencyChange() {
     ASSERT(!isolate()->optimizing_compiler_thread()->IsOptimizerThread());
     abort_due_to_dependency_ = true;
   }
 
   bool HasAbortedDueToDependencyChange() {
     ASSERT(!isolate()->optimizing_compiler_thread()->IsOptimizerThread());
     return abort_due_to_dependency_;
   }
 
+  void set_osr_pc_offset(uint32_t pc_offset) {
+    osr_pc_offset_ = pc_offset;
+  }
+
+  bool HasSameOsrEntry(Handle<JSFunction> function, uint32_t pc_offset) {
+    return osr_pc_offset_ == pc_offset && function.is_identical_to(closure_);
+  }
+
  protected:
   CompilationInfo(Handle<Script> script,
                   Zone* zone);
   CompilationInfo(Handle<SharedFunctionInfo> shared_info,
                   Zone* zone);
   CompilationInfo(HydrogenCodeStub* stub,
                   Isolate* isolate,
                   Zone* zone);
 
  private:
@@ skipping 74 matching lines @@
   v8::Extension* extension_;
   ScriptDataImpl* pre_parse_data_;
 
   // The context of the caller for eval code, and the global context for a
   // global script. Will be a null handle otherwise.
   Handle<Context> context_;
 
   // Compilation mode flag and whether deoptimization is allowed.
   Mode mode_;
   BailoutId osr_ast_id_;
+  // The pc_offset corresponding to osr_ast_id_ in unoptimized code.
+  // We can look this up in the back edge table, but cache it for quick access.
+  uint32_t osr_pc_offset_;
 
   // Flag whether compilation needs to be aborted due to dependency change.
   bool abort_due_to_dependency_;
 
   // The zone from which the compilation pipeline working on this
   // CompilationInfo allocates.
   Zone* zone_;
 
   DeferredHandles* deferred_handles_;
 
@@ skipping 178 matching lines @@
                                                 Handle<Context> context,
                                                 bool is_global,
                                                 LanguageMode language_mode,
                                                 ParseRestriction restriction,
                                                 int scope_position);
 
   // Compile from function info (used for lazy compilation). Returns true on
   // success and false if the compilation resulted in a stack overflow.
   static bool CompileLazy(CompilationInfo* info);
 
-  static void RecompileConcurrent(Handle<JSFunction> function);
+  static bool RecompileConcurrent(Handle<JSFunction> function,
+                                  uint32_t osr_pc_offset = 0);
 
   // Compile a shared function info object (the function is possibly lazily
   // compiled).
   static Handle<SharedFunctionInfo> BuildFunctionInfo(FunctionLiteral* node,
                                                       Handle<Script> script);
 
   // Set the function info for a newly compiled function.
   static void SetFunctionInfo(Handle<SharedFunctionInfo> function_info,
                               FunctionLiteral* lit,
                               bool is_toplevel,
                               Handle<Script> script);
 
-  static void InstallOptimizedCode(OptimizingCompiler* info);
+  static bool InstallOptimizedCode(OptimizingCompiler* info);
+
+  static BailoutId CompileForOnStackReplacement(Handle<JSFunction> function);
+
+  static BailoutId CompileForConcurrentOSR(Handle<JSFunction> function);
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
   static bool MakeCodeForLiveEdit(CompilationInfo* info);
 #endif
 
   static void RecordFunctionCompilation(Logger::LogEventsAndTags tag,
                                         CompilationInfo* info,
                                         Handle<SharedFunctionInfo> shared);
 };
 
@@ skipping 18 matching lines @@
   unsigned info_zone_start_allocation_size_;
   ElapsedTimer timer_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilationPhase);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_COMPILER_H_