+++
title = "Stability of MAC optimisation in Vericert"
date = "2022-11-09"
author = "Yann Herklotz"
tags = []
categories = []
backlinks = ["1c4b"]
forwardlinks = ["5b3"]
zettelid = "1c4b1"
+++

MAC Optimisations ([\#5b3]) for a fused multiply-add operation is not
very stable, because if the intermediate register is used anywhere else,
then it will not be able to fuse the two instructions. This means that
from a local perspective it looks quite random whether or not a series
of multipliers and adds are actually fused. The decision needs a global
property of whether that register is used anywhere, which means that it
is quite unreliable if it will fire or not.

  [\#5b3]: /zettel/5b3