About Core Ops

An Op’s primary role is to function as a node in a directed acyclic graph dependency computation graph.

Core ops are ops that are available and generally useful to all framework bridges and that can be compiled by all transformers. A framework bridge may define framework-specific ops to simplify graph construction, provided that the bridge can enable every transformer to replace all such ops with equivalent subgraphs composed of core ops. Similary, transformers may define transformer-specific ops to represent kernels or other intermediate operations.

If a framework supports extending the set of ops it offers, a bridge may even expose transformer-specific ops to the framework user.

Our design philosophy is that the graph is not a script for running kernels; rather, our compilation will match ops to appropriate kernels for the backend(s) in use. Thus, we expect that adding of new Core ops should be infrequent and that most functionality instead gets added with new functions that build sub-graphs from existing core ops.

It is easiest to define a new op by adapting an existing op. Some of the tasks that must be performed are:

  • Op constructor:
    • Checking type-consistency of arguments
    • Specifying the result type for a call
  • Serializer/Deserializer
  • Transformer handlers:
    • Interpreter (reference) implementation of behavior. The implementation should favor clarity over efficiency.