De-virtualize ArrayData::release.

Of the four horsemen of the SmartAllocator, ArrayData was the only virtual
call. This meant an extra layer of indirection when coming from the TC
to allow the c++ compiler to emit its virtual call, and slightly larger
callsites when using non-generic paths.

While we're moving in this direction, consolidate ArrayData introspection
on its type enum. isSharedMap() was previously implemented with a vtable
slot, and we had no way of asking if an ArrayData was a NameValueTable.

hphp/runtime/base/array/array_data.cpp

@@ -23,6 +23,7 @@
 #include <runtime/base/variable_serializer.h>
 #include <runtime/base/runtime_option.h>
 #include <runtime/base/macros.h>
+#include <runtime/base/shared/shared_map.h>
 #include <util/exception.h>
 #include <tbb/concurrent_hash_map.h>
 
@@ -102,6 +103,22 @@ ArrayData *ArrayData::nonSmartCopy() const {
   throw FatalErrorException("nonSmartCopy not implemented.");
 }
 
+HOT_FUNC
+void ArrayData::release() {
+  if (isHphpArray()) {
+    HphpArray* that = static_cast<HphpArray*>(this);
+    that->release();
+    return;
+  }
+  if (isSharedMap()) {
+    SharedMap* that = static_cast<SharedMap*>(this);
+    that->release();
+    return;
+  }
+  assert(m_kind == kNameValueTableWrapper);
+  // NameValueTableWrapper: nop.
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // reads