Function pre_instantiate_raw

crates/wasmtime/src/runtime/instance.rs:962–1022

Helper function shared between `InstancePre::{instantiate,instantiate_async}` This is an out-of-line function to avoid the generic on `InstancePre` and get this compiled into the `wasmtime` crate to avoid having it monomorphized elsewhere.

(
    store: &mut StoreOpaque,
    module: &Module,
    items: &Arc<TryVec<Definition>>,
    host_funcs: usize,
    func_refs: &Arc<TryVec<VMFuncRef>>,
    asyncness: Asyncness,
)

/// get this compiled into the `wasmtime` crate to avoid having it monomorphized
/// elsewhere.
fn pre_instantiate_raw(
    store: &mut StoreOpaque,
    module: &Module,
    items: &Arc<TryVec<Definition>>,
    host_funcs: usize,
    func_refs: &Arc<TryVec<VMFuncRef>>,
    asyncness: Asyncness,
) -> Result<OwnedImports> {
    // Register this module and use it to fill out any funcref wasm_call holes
    // we can. For more comments on this see `typecheck_externs`.
    let (modules, engine, breakpoints) = store.modules_and_engine_and_breakpoints_mut();
    modules.register_module(module, engine, breakpoints)?;
    let (funcrefs, modules) = store.func_refs_and_modules();
    funcrefs.fill(modules);

    if host_funcs > 0 {
        // Any linker-defined function of the `Definition::HostFunc` variant
        // will insert a function into the store automatically as part of
        // instantiation, so reserve space here to make insertion more efficient
        // as it won't have to realloc during the instantiation.
        funcrefs.reserve_storage(host_funcs)?;

        // The usage of `to_extern_store_rooted` requires that the items are
        // rooted via another means, which happens here by cloning the list of
        // items into the store once. This avoids cloning each individual item
        // below.
        funcrefs.push_instance_pre_definitions(items.clone())?;
        funcrefs.push_instance_pre_func_refs(func_refs.clone())?;
    }

    store.set_async_required(asyncness);

    let mut func_refs = func_refs.iter().map(|f| NonNull::from(f));
    let mut imports = OwnedImports::new(module)?;
    for import in items.iter() {
        if !import.comes_from_same_store(store) {
            bail!("cross-`Store` instantiation is not currently supported");
        }
        // This unsafety should be encapsulated in the constructor of
        // `InstancePre` where the `T` of the original item should match the
        // `T` of the store. Additionally the rooting necessary has happened
        // above.
        let item = match import {
            Definition::Extern(e, _) => e.clone(),
            Definition::HostFunc(func) => unsafe {
                func.to_func_store_rooted(
                    store,
                    if func.func_ref().wasm_call.is_none() {
                        Some(func_refs.next().unwrap())
                    } else {
                        None
                    },
                )
                .into()
            },
        };
        imports.push(&item, store)?;
    }