-/// index. Also identify the WriteResources of this def. When the operand
-/// expands to a sequence of writes, this ID is the last write in the sequence.
+/// index. -1 indicates an invalid latency. Heuristics would typically consider
+/// an instruction with invalid latency to have infinite latency. Also identify
+/// the WriteResources of this def. When the operand expands to a sequence of
+/// writes, this ID is the last write in the sequence.