cascade followed by a final divide.
Note that single-operand or three-operand scalar-dest reduce is perfectly
-well permitted: both still meet the qualifying characteristics that one
-source operand can also be the destination, which allows the "accumulator"
-to be identified.
-
-If the "accumulator" cannot be identified (one of the sources is also
-a destination) the results are **UNDEFINED**. This permits implementations
-to not have to have complex decoding analysis of register fields: it
-is thus up to the programmer to ensure that one of the source registers
-is also a destination register in order to take advantage of Scalar
-Reduce Mode.
+well permitted: the programmer may still declare one register, used as
+both a Vector source and Scalar destination, to be utilised as
+the "accumulator". In the case of `sv.fmadds` and `sv.maddhw` etc
+this naturally fits well with the normal expected usage of these
+operations.
If an interrupt or exception occurs in the middle of the scalar mapreduce,
the scalar destination register **MUST** be updated with the current
as far as the user is concerned, all exceptions and interrupts **MUST**
be precise.
-It is also possible, using this mode, to perform iterative computations.
-Setting the source register to be one greater or one less than the
-destination will result in a cumulative cascade of element-based
-operations being issued to the underlying hardware, where standard
-Register Hazard observance is expected and required. "Reverse Gear"
-may prove useful in some circumstances.
-
## Vector result reduce mode
Vector result reduce mode may utilise the destination vector for