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

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index 229607266004673f87054898df272440f22105f0..890797f41966f5b8a6932f730719f6f22b1a0ff7 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -33,6 +33,7 @@
 #include "isolate.h"
 #include "compilation-cache.h"
 #include "execution.h"
+#include "objects.h"
 #include "snapshot.h"
 #include "platform.h"
 #include "utils.h"
@@ -10873,6 +10874,110 @@ THREADED_TEST(NestedHandleScopeAndContexts) {
 }
 
 
+static i::Handle<i::JSFunction>* foo_ptr = NULL;
+static int foo_count = 0;
+static i::Handle<i::JSFunction>* bar_ptr = NULL;
+static int bar_count = 0;
+
+
+static void entry_hook(uintptr_t function,
+                       uintptr_t return_addr_location) {
+  i::Code* code = i::Code::GetCodeFromTargetAddress(
+      reinterpret_cast<i::Address>(function));
+  CHECK(code != NULL);
+
+  if (bar_ptr != NULL && code == (*bar_ptr)->code())
+    ++bar_count;
+
+  if (foo_ptr != NULL && code == (*foo_ptr)->code())
+    ++foo_count;
+
+  // TODO(siggi): Verify return_addr_location.

[danno, 2012/07/12 15:23:11]

Do you want to do something about the TODO?

[Sigurður Ásgeirsson, 2012/07/12 15:38:54]

I'd prefer to leave it in for now, if that's all right?
I figure that once I have entry hooks for code stubs, I should be able to verify
that the return address seen on foo/bar invocations refers to code that I've
seen before.

+}
+
+
+static void RunLoopInNewEnv() {
+  bar_ptr = NULL;
+  foo_ptr = NULL;
+
+  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; }";
+  CompileRun(script);
+  i::Handle<i::JSFunction> bar =
+      i::Handle<i::JSFunction>::cast(
+          v8::Utils::OpenHandle(*env->Global()->Get(v8_str("bar"))));
+  ASSERT(*bar);
+
+  i::Handle<i::JSFunction> foo =
+      i::Handle<i::JSFunction>::cast(
+           v8::Utils::OpenHandle(*env->Global()->Get(v8_str("foo"))));
+  ASSERT(*foo);
+
+  bar_ptr = &bar;
+  foo_ptr = &foo;
+
+  v8::Handle<v8::Value> value = CompileRun("bar();");
+  CHECK(value->IsNumber());
+  CHECK_EQ(9801.0, v8::Number::Cast(*value)->Value());
+
+  // Test the optimized codegen path.
+  value = CompileRun("%OptimizeFunctionOnNextCall(foo);"
+                     "bar();");
+  CHECK(value->IsNumber());
+  CHECK_EQ(9801.0, v8::Number::Cast(*value)->Value());
+
+  env->Exit();
+}
+
+
+THREADED_TEST(SetFunctionEntryHook) {
+  i::FLAG_allow_natives_syntax = true;
+
+  // Test setting and resetting the entry hook.
+  // Nulling it should alwasy succeed.

[danno, 2012/07/12 15:23:11]

nit: always

[Sigurður Ásgeirsson, 2012/07/12 15:38:54]

Done.

+  CHECK(v8::V8::SetFunctionEntryHook(NULL));
+
+  CHECK(v8::V8::SetFunctionEntryHook(entry_hook));
+  // Setting a hook while one's active should fail.
+  CHECK_EQ(false, v8::V8::SetFunctionEntryHook(entry_hook));
+
+  CHECK(v8::V8::SetFunctionEntryHook(NULL));
+
+  // Reset the entry count to zero and set the entry hook.
+  bar_count = 0;
+  foo_count = 0;
+  CHECK(v8::V8::SetFunctionEntryHook(entry_hook));
+  RunLoopInNewEnv();
+
+  CHECK_EQ(2, bar_count);
+  CHECK_EQ(200, foo_count);
+
+  // Clear the entry hook and count.
+  bar_count = 0;
+  foo_count = 0;
+  v8::V8::SetFunctionEntryHook(NULL);
+
+  // 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(0u == bar_count);
+  CHECK(0u == foo_count);
+}
+
+
 static int64_t cast(intptr_t x) { return static_cast<int64_t>(x); }