**DRAFT**
-`madded` is VA-Form:
+`madded` is similar to v3.0 `madd`.
+`madded`, like `madd`, is VA-Form despite having 2 outputs: the second
+destination register is implicit.
|0.....5|6..10|11..15|16..20|21..25|26..31|
|-------|-----|------|------|------|------|
prod[0:127] = (RA) * (RB)
sum[0:127] = EXTZ(RC) + prod
RT <- sum[64:127]
- RS <- sum[0:63] # RS is either RC or RT+VL
+ RS <- sum[0:63] # RS is either RC or RT+MAXVL
RC is zero-extended (not shifted), the 128-bit product added
to it; the lower half of that result stored in RT and the upper half
When `EXTRA2_MODE` is set to zero, the implicit RS register takes
its Vector/Scalar setting from Rdest_EXTRA2, and takes
the register number from RT, but all numbering
-is offset by VL. *Note that element-width overrides influence this
+is offset by MAXVL. *Note that element-width overrides influence this
offset* (see SVP64 [[svp64/appendix]] for full details).
When `EXTRA2_MODE` is set to one, the implicit RS register is identical