Verification of Parameterised FPGA Circuit Descriptions with Layout ...

Chapter 5
Specialisation
In this chapter we illustrate how Quartz can be used to create specialised, placed designs when
some input values are known at compile-time. Section 5.1 introduces the benefits of design
specialisation and some of its applications. In Section 5.2 we illustrate how we can achieve
distributed specialisation transparently using Quartz “clever components” as primitive ele-
ments. In Section 5.3 we discuss the limitations of our current infrastructure for distributed
specialisation and outline the requirements for an optimal system, while Section 5.4 discusses
the role of specialisation code at a higher-level than primitive components. Section 5.5 illus-
trates high level specialisation of a multiplier circuit and evaluates the performance impact
of compacting designs when logic is optimised away. Section 5.6 summarises this chapter.
5.1 Introduction
Design specialisation is a useful tool that can be used to optimise the performance of digital
circuits when the values of some inputs are known. It is something that is so commonly used
in circuit design as to almost not be worth mentioning with simple optimisations such as
replacing a full multiplier by a constant co-efficient multiplier when one input is fixed or, at
a meta-level, the choice of selecting a multiplier implementation rather than a full ALU for
a circuit that will only perform multiplication.
Typically most design specialisation is static specialisation - a design-time optimisation that
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