00a4e93bcd
This adds a feature which allows one to look up an export by name without knowing what module it's in -- `lookup_global_export` on an `InstanceContents`. The main expected use for this is to support APIs where module A imports a function from module B, and module B needs to access module A's memory. B can't import it from A in the normal way, because that would create a dependency cycle. So for now, allow B to look up A's exported memory dynamically with `lookup_global_export`. In the future, with reference types and possibly host bindings, we'll be able to pass references to memory as arguments, which will obviate the need for this mechanism.
This is the wasmtime-jit crate, which contains JIT-based execution
for wasm, using the wasm ABI defined by wasmtime-environ and the
runtime support provided by wasmtime-runtime.