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The result of the emitter is a vector of bytes holding machine code, jump tables, and (in the future) other read-only data. Some clients, notably Firefox's Wasm compiler, needs to separate the machine code from the data in order to insert more code directly after the code generated by Cranelift. To make such separation possible, we record more information about the emitted bytes: the sizes of each of the sections of code, jump tables, and read-only data, as well as the locations within the code that reference (PC-relatively) the jump tables and read-only data.
This crate provides module-level functionality, which allow multiple functions and data to be emitted with Cranelift and then linked together.
This crate is structured as an optional layer on top of cranelift-codegen. It provides additional functionality, such as linking, however users that require greater flexibility don't need to use it.
A Module is a collection of functions and data objects that are linked
together. Backend is a trait that defines an interface for backends
that compile modules into various forms. Most users will use one of the
following Backend implementations:
SimpleJITBackend, provided by cranelift-simplejit, which JITs code to memory for direct execution.FaerieBackend, provided by cranelift-faerie, which emits native object files.