+++
title = "Parallel semantics of phi functions"
author = "Yann Herklotz"
tags = []
categories = []
backlinks = ["3a8a1"]
forwardlinks = ["3a8a3"]
zettelid = "3a8a2"
+++

The semantics of the phi instructions are parallel, which means that
they all use the same starting state as input, and then update the
registers based on that that phi instruction. Modelling of the phi
instructions as a sequential update is not performed.

There are some cases, however, where the sequential execution of phi
instructions does not lead to equivalent behaviour as the parallel
execution of the instructions. There are then optimisations that can
take advantage of this, and that the inputs and outputs of the phi
instructions are independent.