Port Graph Optimizations

[tanneberger]

About

This pull requests add functionality, so the port graph can be first optimized before instantiating.

• Graph Expansion with Path Merging
• Dead Edge Elimination by looking at triggers and dependencies and taking the shortest path
• Instantiating

Current Algorithm

Create a spanning tree for every port and then squash the edges together so ideally only a tree of depth 1 remains.

Challanges

Given a port-graph like this:

graph TD;
    A-->B;
    X((R1)) --> A;
    B-->D;
    B-->C;
    C-->Y((R2));

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The current graph optimizer would create something like this:

graph TD;
    X((R1)) --> A;
    A-->B;
    A-->C;
    B-->C;
    B-->D;
    A-->D;
    C-->Y((R2));

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If B just forwards data and

Dead Path Elimination

Paths: (A-->D, A-->B and B-->C) can be eliminated with the following reasoning:

• We take a look at all the ports that have triggers. Then taking all the downstream ports that have dependencies and then determine the shortest path between them.

graph TD;
    X((R1)) --> A;
    A-->C;
    C-->Y((R2));

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target Cpp;

reactor A {
    output out: void;
    timer t(500ms);

    reaction (t) -> out {=
        out.set();
    =}
}

reactor C {
    input in: void;

    reaction(in) {=
        std::cout << "C triggert" << std::endl;
    =}
}

reactor D {
    input in: void;

    reaction(in) {=
        std::cout << "D triggert" << std::endl;
    =}
}

reactor B {
    input in: void;

    c = new C();
    d = new D();
    
    in -> c.in;
    in -> d.in;

}


main reactor Forward {
    a = new A();
    b = new B();

    a.out -> b.in;
}

[cmnrd]

Cool!

[cmnrd]

I think all these cases should be invalid for now (except for Phycical + Normal)

[cmnrd]

I think all these cases should be invalid for now (except for PhycicalEnclaved + Normal)

[cmnrd]

The copy constructor is deleted on purpose and we should try to avoid enabling it

[cmnrd]

this can be handled more conveniently in config.hh.in

[cmnrd]

Easier:

  constexpr bool enable_optimizations = (GRAPH_OPTIMIZATIONS == 1);

[cmnrd]

Suggested change

	container->register_action(reinterpret_cast<BaseAction*>(this)); // NOLINT
	container->register_action(static_cast<BaseAction*>(this)); // NOLINT

[cmnrd]

Suggested change

	container->register_reaction(reinterpret_cast<Reaction*>(this)); // NOLINT
	container->register_reaction(static_cast<Reaction*>(this)); // NOLINT

[cmnrd]

I think it would be really helpful to have a more lengthy comment explaining the high level idea of the algorithm.

[cmnrd]

?

[tanneberger]

TODO: Mermaid Function fixen