Use a single entry point with several optional parameters.
Differential Revision: https://reviews.llvm.org/D118776
// integer kind.
std::int32_t RTNAME(ArgumentCount)();
+// 16.9.82 GET_COMMAND
+// Try to get the value of the whole command. All of the parameters are
+// optional.
+// Return a STATUS as described in the standard.
+std::int32_t RTNAME(GetCommand)(const Descriptor *command = nullptr,
+ const Descriptor *length = nullptr, const Descriptor *errmsg = nullptr);
+
// 16.9.83 GET_COMMAND_ARGUMENT
// We're breaking up the interface into several different functions, since most
// of the parameters are optional.