An update, I read about protocols and multimethods. I think multimethods
are a decent way to go (cant use protocols without a defrecord) provided
they work across namespaces.
On Tuesday, April 15, 2014 11:52:36 AM UTC+12, Andrew Chambers wrote:
>
> Hi everyone,
>
> I'm new to clojure and in order to learn I'm working on making some
> compiler tools which converts a lightweight IR code into assembly.
>
> My data model for an IR function is along the lines of
> (def code
> {
> :entry
> [[:loadaddr :x "global_label"]
> [:loadconst 1 :y]
> [:add :x :y :z]
> [:jmp :exit]]
> :exit
> [[:ret :z]]
> })
>
> This, when translated to assembly and after register allocation would turn
> into something like (ignoring calling conventions etc):
> (def assembly-code
> {
> :entry
> [[:x86.lea :eax "global_label"]
> [:x86.loadimm 1, :eax]
> [:x86.add32 :ebx :eax]
> [:jmp :exit]]
> :exit
> [[:ret]]
> })
>
> The problem arises when I have to query the IR code for things like
> accesses-memory? or get-output-vars in an
> extensible way so that multiple target architectures can be supported.
> e.g. (get-output-vars [:add :a :b :c]) -> :c
> (get-output-vars [:x86.add :a :b]) -> :b ;; the input and output
> positions are opcode specific
> (get-output-vars [:x86.add :a :b]) -> :b
> (get-output-vars [:divmod :a :b :c :d]) -> :c :d
> (accesses-memory? :x86.add) -> false
> (accesses-memory? :x86.load) -> true
> (accesses-memory? :loadconst) ->false
> I have to be able to write these functions in a way that knows about the
> format of the basic IR opcodes, but can also be extended
> to handle opcodes of architectures that don't exist in my code yet, the
> extensions would exist within the namespaces of that specific architecture
> and shouldn't need to modify the code for the built in opcodes.
>
> What is the most seamless and efficient way to achieve this sort of
> function extension in clojure? Also, how would I allow sharing
> of implementations where instructions have similar layouts.
>
> e.g.
> (get-output-vars [:add :a :b :c]) -> :c
> (get-output-vars [:sub :a :b :c]) -> :c
>
>
>
>
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