* but this is replaced when op is grafted in, when
* this op will point to the real next op, and the new
* parent takes over role of remembering starting op.)
+ * op_sibparent Pointer to the op's next sibling, or to the parent
+ * if there are no more siblings.
* op_ppaddr Pointer to current ppcode's function.
+ * op_targ An index into the current pad, identifying an SV
+ * that is typically used to store the OP's result
+ * (such as a lexical variable, or a SVs_PADTMP
+ * temporary intermediate value).
* op_type The type of the operation.
* op_opt Whether or not the op has been optimised by the
* peephole optimiser.