[turbofan] Collect invocation counts and compute relative call frequencies.

src/type-feedback-vector.cc

Index: src/type-feedback-vector.cc
diff --git a/src/type-feedback-vector.cc b/src/type-feedback-vector.cc
index b4886ce2cfab28d570a076d3c57b5df7dd1a9dc7..e21ad93ba6dfff57abe0111222f679598ea88664 100644
--- a/src/type-feedback-vector.cc
+++ b/src/type-feedback-vector.cc
@@ -230,11 +230,13 @@ Handle<TypeFeedbackVector> TypeFeedbackVector::New(
   const int slot_count = metadata->slot_count();
   const int length = slot_count + kReservedIndexCount;
   if (length == kReservedIndexCount) {
-    return Handle<TypeFeedbackVector>::cast(factory->empty_fixed_array());
+    return Handle<TypeFeedbackVector>::cast(
+        factory->empty_type_feedback_vector());
   }
 
   Handle<FixedArray> array = factory->NewFixedArray(length, TENURED);
   array->set(kMetadataIndex, *metadata);
+  array->set(kInvocationCountIndex, Smi::FromInt(0));
 
   DisallowHeapAllocation no_gc;
 
@@ -628,6 +630,12 @@ int CallICNexus::ExtractCallCount() {
   return value;
 }
 
+float CallICNexus::ComputeCallFrequency() {
+  double const invocation_count = vector()->invocation_count();
+  double const call_count = ExtractCallCount();
+  return static_cast<float>(call_count / invocation_count);
+}
+
 void CallICNexus::Clear(Code* host) { CallIC::Clear(GetIsolate(), host, this); }
 
 void CallICNexus::ConfigureUninitialized() {