Use optimized code map to cache OSR code.

src/runtime.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 8687 matching lines @@
         FindReadyOSRCandidate(function, pc_offset);
 
     if (job == NULL) {
       if (IsSuitableForOnStackReplacement(isolate, function, unoptimized) &&
           Compiler::RecompileConcurrent(function, pc_offset)) {
         if (function->IsMarkedForLazyRecompilation() ||
             function->IsMarkedForConcurrentRecompilation()) {
           // Prevent regular recompilation if we queue this for OSR.
           // TODO(yangguo): remove this as soon as OSR becomes one-shot.
           function->ReplaceCode(*unoptimized);
+        } else if (function->IsOptimized() &&
+                   !isolate->optimizing_compiler_thread()->
+                       IsQueuedForOSR(function, pc_offset)) {
+          // Function has already been optimized and no OSR job has been queued.
+          // This means that we have found cached code.
+          result = Handle<Code>(function->code());
+          ast_id = result->OsrAstId();
+          ASSERT(!ast_id.IsNone());
+          ASSERT_EQ(ast_id.ToInt(),
+                    unoptimized->TranslatePcOffsetToAstId(pc_offset).ToInt());
+          // Fall through to the part where we use the OSR code.
+        } else {
+          return NULL;
         }
-        return NULL;
       }
       // Fall through to the end in case of failure.
     } else {
       // TODO(titzer): don't install the OSR code into the function.
       ast_id = job->info()->osr_ast_id();
       result = Compiler::InstallOptimizedCode(job);
     }
   } else if (IsSuitableForOnStackReplacement(isolate, function, unoptimized)) {
     ast_id = unoptimized->TranslatePcOffsetToAstId(pc_offset);
     ASSERT(!ast_id.IsNone());
@@ skipping 6195 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal