Cache hash code for closures.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index d447c93c07974800b1b7eed09d92a695f0fbbebd..516c6ded8ae27ceb7a6eaad1129fe7d3b1767d8b 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -6845,6 +6845,28 @@ RawInstance* Function::ImplicitInstanceClosure(const Instance& receiver) const {
 }
 
 
+RawSmi* Function::GetClosureHashCode() const {
+  ASSERT(IsClosureFunction());
+  const Object& obj = Object::Handle(raw_ptr()->data_);
+  ASSERT(!obj.IsNull());
+  if (ClosureData::Cast(obj).hash() != Object::null()) {
+    return Smi::RawCast(ClosureData::Cast(obj).hash());
+  }
+  // Hash not yet computed. Compute and cache it.
+  const Class& cls = Class::Handle(Owner());
+  intptr_t result = String::Handle(name()).Hash();
+  result += String::Handle(Signature()).Hash();
+  result += String::Handle(cls.Name()).Hash();
+  // Finalize hash value like for strings so that it fits into a smi.
+  result += result << 3;
+  result ^= result >> 11;
+  result += result << 15;
+  result &= ((static_cast<intptr_t>(1) << String::kHashBits) - 1);
+  ClosureData::Cast(obj).set_hash(result);
+  return Smi::New(result);
+}
+
+
 RawString* Function::BuildSignature(bool instantiate,
                                     NameVisibility name_visibility,
                                     const TypeArguments& instantiator) const {
@@ -7221,6 +7243,11 @@ void ClosureData::set_implicit_static_closure(const Instance& closure) const {
 }
 
 
+void ClosureData::set_hash(intptr_t value) const {
+  StorePointer(&raw_ptr()->hash_, static_cast<RawObject*>(Smi::New(value)));
+}
+
+
 void ClosureData::set_parent_function(const Function& value) const {
   StorePointer(&raw_ptr()->parent_function_, value.raw());
 }