Revert "Improve hashCode for closure objects"

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 43620a8200584ffe9d1ada17b62cd7e14fbb7678..3a45edf9bf946230095921753dafe12b4d63331c 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -6889,13 +6889,25 @@ RawInstance* Function::ImplicitInstanceClosure(const Instance& receiver) const {
                       *this, context);
 }
 
-intptr_t Function::ComputeClosureHash() 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();
-  return result;
+  // 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(NameVisibility name_visibility) const {
@@ -7315,6 +7327,10 @@ void ClosureData::set_implicit_static_closure(const Instance& closure) const {
   StorePointer(&raw_ptr()->closure_, closure.raw());
 }
 
+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());
 }
@@ -14864,10 +14880,6 @@ RawObject* Instance::HashCode() const {
   return DartLibraryCalls::HashCode(*this);
 }
 
-RawObject* Instance::IdentityHashCode() const {
-  return DartLibraryCalls::IdentityHashCode(*this);
-}
-
 bool Instance::CanonicalizeEquals(const Instance& other) const {
   if (this->raw() == other.raw()) {
     return true;  // "===".
@@ -21657,36 +21669,6 @@ const char* Closure::ToCString() const {
                      from, fun_desc);
 }
 
-int64_t Closure::ComputeHash() const {
-  const Function& func = Function::Handle(function());
-  uint32_t result = 0;
-  if (func.IsImplicitInstanceClosureFunction()) {
-    // Implicit instance closures are not unqiue, so combine function's hash
-    // code with identityHashCode of cached receiver.
-    result = static_cast<uint32_t>(func.ComputeClosureHash());
-    const Context& context = Context::Handle(this->context());
-    const Object& receiver = Object::Handle(context.At(0));
-    const Object& receiverHash =
-        Object::Handle(Instance::Cast(receiver).IdentityHashCode());
-    if (receiverHash.IsError()) {
-      Exceptions::PropagateError(Error::Cast(receiverHash));
-      UNREACHABLE();
-    }
-    result = CombineHashes(
-        result, Integer::Cast(receiverHash).AsTruncatedUint32Value());
-  } else {
-    // Explicit closures and implicit static closures are unique,
-    // so identityHashCode of closure object is good enough.
-    const Object& identityHash = Object::Handle(this->IdentityHashCode());
-    if (identityHash.IsError()) {
-      Exceptions::PropagateError(Error::Cast(identityHash));
-      UNREACHABLE();
-    }
-    result = Integer::Cast(identityHash).AsTruncatedUint32Value();
-  }
-  return FinalizeHash(result, String::kHashBits);
-}
-
 RawClosure* Closure::New(const TypeArguments& instantiator_type_arguments,
                          const TypeArguments& function_type_arguments,
                          const Function& function,