Implements a new API to set a function entry hook for profiling.

test/cctest/test-api.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 10855 matching lines @@
   v8::Persistent<Context> env = Context::New();
   env->Enter();
   v8::Handle<Value> value = NestedScope(env);
   v8::Handle<String> str(value->ToString());
   CHECK(!str.IsEmpty());
   env->Exit();
   env.Dispose();
 }
 
 
+#if defined(V8_HOST_ARCH_IA32)
+static size_t entry_count = 0;
+
+
+__declspec(naked) static void entry_hook() {
+  __asm {
+    inc entry_count
+    ret
+  }
+}
+
+
+static void RunLoopInNewEnv() {
+  v8::HandleScope outer;
+  v8::Persistent<Context> env = Context::New();
+  env->Enter();
+
+  const char* script =
+      "function bar() {"
+      "  var sum = 0;"
+      "  for (i = 0; i < 100; ++i)"
+      "    sum = foo(i);"
+      "  return sum;"
+      "}"
+      "function foo(i) { return i * i; }"

[danno, 2012/06/27 23:01:54]

To test optimized code, you can for V8 to optimize a function the next time it
gets called. You need to call OptimizeFunctionOnNextCall, take a look at the
test case in "UndetectableOptimized" for an example of usage. Make sure that you
called the unoptimized version of a function at least once before optimizing it,
otherwise we won't have type information and will likely deopt immediately after
optimizing, and you won't be testing what you think.

[Sigurður Ásgeirsson, 2012/06/28 10:35:34]

Done.

+      "bar();";
+  v8::Handle<v8::Value> value = CompileRun(script);
+  CHECK(value->IsNumber());
+  CHECK_EQ(9801.0, v8::Number::Cast(*value)->Value());
+  env->Exit();
+}
+
+
+THREADED_TEST(SetFunctionEntryHook) {
+  // Reset the entry count to zero and set the entry hook.
+  entry_count = 0;
+  v8::V8::SetFunctionEntryHook(reinterpret_cast<uintptr_t>(entry_hook));
+  RunLoopInNewEnv(); 
+  // TODO(siggi): This will fail if ever V8 inlines the function foo().
+  CHECK_LE(102, entry_count);
+
+  // Clear the entry hook and count.
+  entry_count = 0;
+  v8::V8::SetFunctionEntryHook(0);
+  
+  // Clear the compilation cache to make sure we don't reuse the
+  // functions from the previous invocation.
+  v8::internal::Isolate::Current()->compilation_cache()->Clear();
+
+  // Verify that entry hooking is now disabled.
+  RunLoopInNewEnv(); 
+  CHECK_EQ(0, entry_count);
+}
+#endif
+
+
 static int64_t cast(intptr_t x) { return static_cast<int64_t>(x); }
 
 
 THREADED_TEST(ExternalAllocatedMemory) {
   v8::HandleScope outer;
   v8::Persistent<Context> env(Context::New());
   CHECK(!env.IsEmpty());
   const intptr_t kSize = 1024*1024;
   CHECK_EQ(cast(v8::V8::AdjustAmountOfExternalAllocatedMemory(kSize)),
            cast(kSize));
@@ skipping 5920 matching lines @@
         "  x++;                      \n"
         "  throw new Error('again'); \n"  // This is the new uncaught error.
         "}                           \n";
     CompileRun(throw_again);
     CHECK(try_catch.HasCaught());
     Local<Message> message = try_catch.Message();
     CHECK(!message.IsEmpty());
     CHECK_EQ(6, message->GetLineNumber());
   }
 }