test.cc

#define JSDynamicCast(To) \
    [] (auto from) -> To { \
        static thread_local const JSC::ClassInfo* cache = nullptr; \
        auto* classInfo = extractClassInfo(from); \
        if (UNLIKELY(!classInfo)) \
            return nullptr; \
        if (classInfo == cache) \
            return JSC::jsCast<To>(from); \
        auto* result = JSC::jsDynamicCast<To>(from); \
        if (result) \
            cache = classInfo; \
        return result; \
    }