Implement glue for V8 JIT code profiling.

chrome/common/profiling.cc

Index: chrome/common/profiling.cc
diff --git a/chrome/common/profiling.cc b/chrome/common/profiling.cc
index 1acb43fea13a9d4e0e4bb58ffa0d61710f461cba..1eb5829dc96bb31306e8e4e28f165106bb3461e9 100644
--- a/chrome/common/profiling.cc
+++ b/chrome/common/profiling.cc
@@ -16,6 +16,25 @@
 #include "v8/include/v8.h"
 
 namespace {
+
+base::debug::AddDynamicSymbol add_dynamic_symbol_func = NULL;
+base::debug::MoveDynamicSymbol move_dynamic_symbol_func = NULL;
+
+void JitCodeEventHandler(const v8::JitCodeEvent* event) {
+  DCHECK(add_dynamic_symbol_func != NULL &&  move_dynamic_symbol_func != NULL);

[jar (doing other things), 2013/06/22 00:38:14]

nit: probably better is a pair of DCHECK_NE() 

[Sigurður Ásgeirsson, 2013/06/27 17:42:35]

Done.

+
+  switch (event->type) {
+   case v8::JitCodeEvent::CODE_ADDED:

[jar (doing other things), 2013/06/22 00:38:14]

nit: indent 2 to the "case" and then 2 more (below) for the body of the case.

[Sigurður Ásgeirsson, 2013/06/27 17:42:35]

Done.

+    add_dynamic_symbol_func(event->code_start, event->code_len,
+                            event->name.str, event->name.len);
+    break;
+
+   case v8::JitCodeEvent::CODE_MOVED:
+    move_dynamic_symbol_func(event->code_start, event->new_code_start);
+    break;
+  }
+}
+
 std::string GetProfileName() {
   static const char kDefaultProfileName[] = "chrome-profile-{type}-{pid}";
   CR_DEFINE_STATIC_LOCAL(std::string, profile_name, ());
@@ -103,8 +122,7 @@ void Profiling::ProcessStarted() {
   std::string process_type =
       command_line.GetSwitchValueASCII(switches::kProcessType);
 
-  // Establish the V8 return address resolution hook if we're
-  // an instrumented binary.
+  // Establish the V8 profiling hooks if we're an instrumented binary.
   if (base::debug::IsBinaryInstrumented()) {
     base::debug::ReturnAddressLocationResolver resolve_func =
         base::debug::GetProfilerReturnAddrResolutionFunc();
@@ -112,6 +130,25 @@ void Profiling::ProcessStarted() {
     if (resolve_func != NULL) {
       v8::V8::SetReturnAddressLocationResolver(resolve_func);
     }
+
+    // Set up the JIT code entry handler and the symbol callbacks if the
+    // profiler supplies them.
+    // TODO(siggi): Maybe add a switch or an environment variable to turn off
+    //    V8 profiling?
+    base::debug::DynamicFunctionEntryHook entry_hook_func =
+        base::debug::GetProfilerDynamicFunctionEntryHookFunc();
+    add_dynamic_symbol_func = base::debug::GetProfilerAddDynamicSymbolFunc();
+    move_dynamic_symbol_func = base::debug::GetProfilerMoveDynamicSymbolFunc();
+
+    v8::Isolate* isolate = v8::Isolate::GetCurrent();
+    if (isolate != NULL &&
+        entry_hook_func != NULL &&
+        add_dynamic_symbol_func != NULL &&
+        move_dynamic_symbol_func != NULL) {
+      v8::V8::SetFunctionEntryHook(isolate, entry_hook_func);
+      v8::V8::SetJitCodeEventHandler(v8::kJitCodeEventDefault,
+                                     &JitCodeEventHandler);
+    }
   }
 
   if (command_line.HasSwitch(switches::kProfilingAtStart)) {