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..4eafd4ff250f025f2a38bf683a097b57fda862cd 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 +10874,89 @@ THREADED_TEST(NestedHandleScopeAndContexts) {
 }
 
 
+static size_t entry_count = 0;
+static uint64_t last_cycles = 0;
+
+
+static void entry_hook(intptr_t function,
+                       intptr_t stack_pointer,
+                       uint64_t entry_time) {
+  CHECK(entry_time >= last_cycles);
+
+  i::Code* code = i::Code::GetCodeFromTargetAddress(
+      reinterpret_cast<i::Address>(function));
+  CHECK(code != NULL);
+
+  // TODO(siggi): How can I reach back to the JS function objects and test
+  //    some of their properties (like name)?
+
+  last_cycles = entry_time;
+  ++entry_count;
+}
+
+
+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; }"
+      "bar();";
+  v8::Handle<v8::Value> value = CompileRun(script);
+  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.
+  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.
+  entry_count = 0;
+  CHECK(v8::V8::SetFunctionEntryHook(entry_hook));
+  RunLoopInNewEnv(); 
+  // TODO(siggi): This will fail if ever V8 inlines the function foo() above.
+  CHECK_LE(204, entry_count);
+
+  // Clear the entry hook and count.
+  entry_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 == entry_count);
+}
+
+
 static int64_t cast(intptr_t x) { return static_cast<int64_t>(x); }