Print real-time V8 JIT code events.

trace-jit-code-events.patch

diff --git a/src/node.cc b/src/node.cc
index 32cff12..3c5b616 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -2954,6 +2954,36 @@ static char **copy_argv(int argc, char **argv) {
   return argv_copy;
 }
 
+
+static void OnJitCodeEvent(const JitCodeEvent* event) {
+  switch (event->type) {
+  case JitCodeEvent::CODE_ADDED:
+    printf("CODE_ADDED code_start=%p code_len=%zu name=\"%.*s\"\n",
+           event->code_start,
+           event->code_len,
+           (int) event->name.len,
+           event->name.str);
+    break;
+
+  case JitCodeEvent::CODE_MOVED:
+    printf("CODE_MOVED code_start=%p code_len=%zu new_code_start=%p\n",
+           event->code_start,
+           event->code_len,
+           event->new_code_start);
+    break;
+
+  case JitCodeEvent::CODE_REMOVED:
+    printf("CODE_REMOVED code_start=%p code_len=%zu\n",
+           event->code_start,
+           event->code_len);
+    break;
+
+  default:
+    ;  // Ignore.
+  }
+}
+
+
 int Start(int argc, char *argv[]) {
   // Hack aroung with the argv pointer. Used for process.title = "blah".
   argv = uv_setup_args(argc, argv);
@@ -2967,6 +2997,7 @@ int Start(int argc, char *argv[]) {
   Init(argc, argv_copy);
 
   V8::Initialize();
+  V8::SetJitCodeEventHandler(kJitCodeEventEnumExisting, OnJitCodeEvent);
   {
     Locker locker;
     HandleScope handle_scope;