Serialize and deserialize compilation artifacts. (#2020)

* Serialize and deserialize Module
* Use bincode to serialize
* Add wasm_module_serialize; docs
* Simple tests

tests/all/module_serialize.rs

@@ -0,0 +1,48 @@
+use anyhow::{bail, Result};
+use wasmtime::*;
+
+fn serialize(engine: &Engine, wat: &'static str) -> Result<Vec<u8>> {
+    let module = Module::new(&engine, wat)?;
+    Ok(module.serialize()?)
+}
+
+fn deserialize_and_instantiate(store: &Store, buffer: &[u8]) -> Result<Instance> {
+    let module = Module::deserialize(store.engine(), buffer)?;
+    Ok(Instance::new(&store, &module, &[])?)
+}
+
+#[test]
+fn test_module_serialize_simple() -> Result<()> {
+    let buffer = serialize(
+        &Engine::default(),
+        "(module (func (export \"run\") (result i32) i32.const 42))",
+    )?;
+
+    let store = Store::default();
+    let instance = deserialize_and_instantiate(&store, &buffer)?;
+    let run = instance
+        .get_func("run")
+        .ok_or(anyhow::format_err!("failed to find `run` function export"))?
+        .get0::<i32>()?;
+    let result = run()?;
+
+    assert_eq!(42, result);
+    Ok(())
+}
+
+#[test]
+fn test_module_serialize_fail() -> Result<()> {
+    let buffer = serialize(
+        &Engine::default(),
+        "(module (func (export \"run\") (result i32) i32.const 42))",
+    )?;
+
+    let mut config = Config::new();
+    config.cranelift_opt_level(OptLevel::None);
+    let store = Store::new(&Engine::new(&config));
+    match deserialize_and_instantiate(&store, &buffer) {
+        Ok(_) => bail!("expected failure at deserialization"),
+        Err(_) => (),
+    }
+    Ok(())
+}