addMulVVW is an unnecessarily special case.
All other assembly routines taking []Word (V as in vector) arguments
take separate source and destination. For example:
addVV: z = x+y
mulAddVWW: z = x*m+a
addMulVVW uses the z parameter as both destination and source:
addMulVVW: z = z+x*m
Even looking at the signatures is confusing: all the VV routines take
two input vectors x and y, but addMulVVW takes only x: where is y?
(The answer is that the two inputs are z and x.)
It would be nice to fix this, both for understandability and regularity,
and to simplify a future assembly generator.
We cannot remove or redefine addMulVVW, because it has been used
in linknames. Instead, the CL adds a new final addend argument ‘a’
like in mulAddVWW, making the natural name addMulVVWW
(two input vectors, two input words):
addMulVVWW: z = x+y*m+a
This CL updates all the assembly implementations to rename the
inputs z, x, y -> x, y, m, and then introduces a separate destination z.
Change-Id: Ib76c80b53f6d1f4a901f663566e9c4764bb20488
Reviewed-on: https://go-review.googlesource.com/c/go/+/664895
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Alan Donovan <adonovan@google.com>