Statically register host WASM functions (#10394)

* Statically register host WASM functions

* Fix `substrate-test-client` compilation

* Move `ExtendedHostFunctions` to `sp-wasm-interface`

* Fix `sp-runtime-interface` tests' compilation

* Fix `sc-executor-wasmtime` tests' compilation

* Use `runtime_interface` macro in `test-runner`

* Fix `sc-executor` tests' compilation

* Reformatting/`rustfmt`

* Add an extra comment regarding the `H` generic arg in `create_runtime`

* Even more `rustfmt`

* Depend on `wasmtime` without default features in `sp-wasm-interface`

* Bump version of `sp-wasm-interface` to 4.0.1

* Bump `sp-wasm-interface` in `Cargo.lock` too

* Bump all of the `sp-wasm-interface` requirements to 4.0.1

Maybe this will appease cargo-unleash?

* Revert "Bump all of the `sp-wasm-interface` requirements to 4.0.1"

This reverts commit 0f7ccf8e0f371542861121b145ab87af6541ac30.

* Make `cargo-unleash` happy (maybe)

* Use `cargo-unleash` to bump the crates' versions

* Align to review comments

substrate/primitives/core/Cargo.toml

@@ -69,7 +69,7 @@ libsecp256k1 = { version = "0.7", default-features = false, features = ["hmac",
 merlin = { version = "2.0", default-features = false, optional = true }
 ss58-registry = { version = "1.5.0", default-features = false }
 sp-core-hashing = { version = "4.0.0", path = "./hashing", default-features = false, optional = true }
-sp-runtime-interface = { version = "4.0.0", default-features = false, path = "../runtime-interface" }
+sp-runtime-interface = { version = "4.1.0-dev", default-features = false, path = "../runtime-interface" }
 
 [dev-dependencies]
 sp-serializer = { version = "4.0.0-dev", path = "../serializer" }

substrate/primitives/io/Cargo.toml

@@ -22,8 +22,8 @@ sp-keystore = { version = "0.10.0-dev", default-features = false, optional = tru
 sp-std = { version = "4.0.0", default-features = false, path = "../std" }
 libsecp256k1 = { version = "0.7", optional = true }
 sp-state-machine = { version = "0.10.0-dev", optional = true, path = "../state-machine" }
-sp-wasm-interface = { version = "4.0.0", path = "../wasm-interface", default-features = false }
-sp-runtime-interface = { version = "4.0.0", default-features = false, path = "../runtime-interface" }
+sp-wasm-interface = { version = "4.1.0-dev", path = "../wasm-interface", default-features = false }
+sp-runtime-interface = { version = "4.1.0-dev", default-features = false, path = "../runtime-interface" }
 sp-trie = { version = "4.0.0-dev", optional = true, path = "../trie" }
 sp-externalities = { version = "0.10.0", optional = true, path = "../externalities" }
 sp-tracing = { version = "4.0.0", default-features = false, path = "../tracing" }

substrate/primitives/runtime-interface/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sp-runtime-interface"
-version = "4.0.0"
+version = "4.1.0-dev"
 authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2021"
 license = "Apache-2.0"
@@ -14,7 +14,7 @@ readme = "README.md"
 targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
-sp-wasm-interface = { version = "4.0.0", path = "../wasm-interface", default-features = false }
+sp-wasm-interface = { version = "4.1.0-dev", path = "../wasm-interface", default-features = false }
 sp-std = { version = "4.0.0", default-features = false, path = "../std" }
 sp-tracing = { version = "4.0.0", default-features = false, path = "../tracing" }
 sp-runtime-interface-proc-macro = { version = "4.0.0", path = "proc-macro" }

substrate/primitives/runtime-interface/proc-macro/src/runtime_interface/host_function_interface.rs

@@ -35,11 +35,11 @@ use syn::{
 
 use proc_macro2::{Span, TokenStream};
 
-use quote::{quote, ToTokens};
+use quote::quote;
 
 use inflector::Inflector;
 
-use std::iter::{self, Iterator};
+use std::iter::Iterator;
 
 /// Generate the extern host functions for wasm and the `HostFunctions` struct that provides the
 /// implementations for the host functions on the host.
@@ -163,14 +163,20 @@ fn generate_host_functions_struct(
 ) -> Result<TokenStream> {
 	let crate_ = generate_crate_access();
 
-	let host_functions = get_runtime_interface(trait_def)?
-		.all_versions()
-		.map(|(version, method)| {
-			generate_host_function_implementation(&trait_def.ident, method, version, is_wasm_only)
-		})
-		.collect::<Result<Vec<_>>>()?;
+	let mut host_function_impls = Vec::new();
+	let mut host_function_names = Vec::new();
+	let mut register_bodies = Vec::new();
+	for (version, method) in get_runtime_interface(trait_def)?.all_versions() {
+		let (implementation, name, register_body) =
+			generate_host_function_implementation(&trait_def.ident, method, version, is_wasm_only)?;
+		host_function_impls.push(implementation);
+		host_function_names.push(name);
+		register_bodies.push(register_body);
+	}
 
 	Ok(quote! {
+		#(#host_function_impls)*
+
 		/// Provides implementations for the extern host functions.
 		#[cfg(feature = "std")]
 		pub struct HostFunctions;
@@ -178,7 +184,16 @@ fn generate_host_functions_struct(
 		#[cfg(feature = "std")]
 		impl #crate_::sp_wasm_interface::HostFunctions for HostFunctions {
 			fn host_functions() -> Vec<&'static dyn #crate_::sp_wasm_interface::Function> {
-				vec![ #( #host_functions ),* ]
+				vec![ #( &#host_function_names as &dyn #crate_::sp_wasm_interface::Function ),* ]
+			}
+
+			#crate_::sp_wasm_interface::if_wasmtime_is_enabled! {
+				fn register_static<T>(registry: &mut T) -> core::result::Result<(), T::Error>
+					where T: #crate_::sp_wasm_interface::HostFunctionRegistry
+				{
+					#(#register_bodies)*
+					Ok(())
+				}
 			}
 		}
 	})
@@ -194,47 +209,182 @@ fn generate_host_function_implementation(
 	method: &TraitItemMethod,
 	version: u32,
 	is_wasm_only: bool,
-) -> Result<TokenStream> {
+) -> Result<(TokenStream, Ident, TokenStream)> {
 	let name = create_host_function_ident(&method.sig.ident, version, trait_name).to_string();
 	let struct_name = Ident::new(&name.to_pascal_case(), Span::call_site());
 	let crate_ = generate_crate_access();
 	let signature = generate_wasm_interface_signature_for_host_function(&method.sig)?;
-	let wasm_to_ffi_values =
-		generate_wasm_to_ffi_values(&method.sig, trait_name).collect::<Result<Vec<_>>>()?;
-	let ffi_to_host_values = generate_ffi_to_host_value(&method.sig).collect::<Result<Vec<_>>>()?;
-	let host_function_call = generate_host_function_call(&method.sig, version, is_wasm_only);
-	let into_preallocated_ffi_value = generate_into_preallocated_ffi_value(&method.sig)?;
-	let convert_return_value = generate_return_value_into_wasm_value(&method.sig);
 
-	Ok(quote! {
-		{
-			struct #struct_name;
+	let fn_name = create_function_ident_with_version(&method.sig.ident, version);
+	let ref_and_mut = get_function_argument_types_ref_and_mut(&method.sig);
 
-			impl #crate_::sp_wasm_interface::Function for #struct_name {
-				fn name(&self) -> &str {
-					#name
-				}
+	// List of variable names containing WASM FFI-compatible arguments.
+	let mut ffi_names = Vec::new();
 
-				fn signature(&self) -> #crate_::sp_wasm_interface::Signature {
-					#signature
-				}
+	// List of `$name: $ty` tokens containing WASM FFI-compatible arguments.
+	let mut ffi_args_prototype = Vec::new();
 
-				fn execute(
-					&self,
-					__function_context__: &mut dyn #crate_::sp_wasm_interface::FunctionContext,
-					args: &mut dyn Iterator<Item = #crate_::sp_wasm_interface::Value>,
-				) -> std::result::Result<Option<#crate_::sp_wasm_interface::Value>, String> {
-					#( #wasm_to_ffi_values )*
-					#( #ffi_to_host_values )*
-					#host_function_call
-					#into_preallocated_ffi_value
-					#convert_return_value
-				}
+	// List of variable names containing arguments already converted into native Rust types.
+	// Also includes the preceding `&` or `&mut`. To be used to call the actual implementation of
+	// the host function.
+	let mut host_names_with_ref = Vec::new();
+
+	// List of code snippets to copy over the results returned from a host function through
+	// any `&mut` arguments back into WASM's linear memory.
+	let mut copy_data_into_ref_mut_args = Vec::new();
+
+	// List of code snippets to convert dynamic FFI args (`Value` enum) into concrete static FFI
+	// types (`u32`, etc.).
+	let mut convert_args_dynamic_ffi_to_static_ffi = Vec::new();
+
+	// List of code snippets to convert static FFI args (`u32`, etc.) into native Rust types.
+	let mut convert_args_static_ffi_to_host = Vec::new();
+
+	for ((host_name, host_ty), ref_and_mut) in
+		get_function_argument_names_and_types_without_ref(&method.sig).zip(ref_and_mut)
+	{
+		let ffi_name = generate_ffi_value_var_name(&host_name)?;
+		let host_name_ident = match *host_name {
+			Pat::Ident(ref pat_ident) => pat_ident.ident.clone(),
+			_ => unreachable!("`generate_ffi_value_var_name` above would return an error on `Pat` != `Ident`; qed"),
+		};
+
+		let ffi_ty = quote! { <#host_ty as #crate_::RIType>::FFIType };
+		ffi_args_prototype.push(quote! { #ffi_name: #ffi_ty });
+		ffi_names.push(quote! { #ffi_name });
+
+		let convert_arg_error = format!(
+			"could not marshal the '{}' argument through the WASM FFI boundary while executing '{}' from interface '{}'",
+			host_name_ident,
+			method.sig.ident,
+			trait_name
+		);
+		convert_args_static_ffi_to_host.push(quote! {
+			let mut #host_name = <#host_ty as #crate_::host::FromFFIValue>::from_ffi_value(__function_context__, #ffi_name)
+				.map_err(|err| format!("{}: {}", err, #convert_arg_error))?;
+		});
+
+		let ref_and_mut_tokens =
+			ref_and_mut.map(|(token_ref, token_mut)| quote!(#token_ref #token_mut));
+
+		host_names_with_ref.push(quote! { #ref_and_mut_tokens #host_name });
+
+		if ref_and_mut.map(|(_, token_mut)| token_mut.is_some()).unwrap_or(false) {
+			copy_data_into_ref_mut_args.push(quote! {
+				<#host_ty as #crate_::host::IntoPreallocatedFFIValue>::into_preallocated_ffi_value(
+					#host_name,
+					__function_context__,
+					#ffi_name,
+				)?;
+			});
+		}
+
+		let arg_count_mismatch_error = format!(
+			"missing argument '{}': number of arguments given to '{}' from interface '{}' does not match the expected number of arguments",
+			host_name_ident,
+			method.sig.ident,
+			trait_name
+		);
+		convert_args_dynamic_ffi_to_static_ffi.push(quote! {
+			let #ffi_name = args.next().ok_or_else(|| #arg_count_mismatch_error.to_owned())?;
+			let #ffi_name: #ffi_ty = #crate_::sp_wasm_interface::TryFromValue::try_from_value(#ffi_name)
+				.ok_or_else(|| #convert_arg_error.to_owned())?;
+		});
+	}
+
+	let ffi_return_ty = match &method.sig.output {
+		ReturnType::Type(_, ty) => quote! { <#ty as #crate_::RIType>::FFIType },
+		ReturnType::Default => quote! { () },
+	};
+
+	let convert_return_value_host_to_static_ffi = match &method.sig.output {
+		ReturnType::Type(_, ty) => quote! {
+			let __result__ = <#ty as #crate_::host::IntoFFIValue>::into_ffi_value(
+				__result__,
+				__function_context__
+			);
+		},
+		ReturnType::Default => quote! {
+			let __result__ = Ok(__result__);
+		},
+	};
+
+	let convert_return_value_static_ffi_to_dynamic_ffi = match &method.sig.output {
+		ReturnType::Type(_, _) => quote! {
+			let __result__ = Ok(Some(#crate_::sp_wasm_interface::IntoValue::into_value(__result__)));
+		},
+		ReturnType::Default => quote! {
+			let __result__ = Ok(None);
+		},
+	};
+
+	if is_wasm_only {
+		host_names_with_ref.push(quote! {
+			__function_context__
+		});
+	}
+
+	let implementation = quote! {
+		#[cfg(feature = "std")]
+		struct #struct_name;
+
+		#[cfg(feature = "std")]
+		impl #struct_name {
+			fn call(
+				__function_context__: &mut dyn #crate_::sp_wasm_interface::FunctionContext,
+				#(#ffi_args_prototype),*
+			) -> std::result::Result<#ffi_return_ty, String> {
+				#(#convert_args_static_ffi_to_host)*
+				let __result__ = #fn_name(#(#host_names_with_ref),*);
+				#(#copy_data_into_ref_mut_args)*
+				#convert_return_value_host_to_static_ffi
+				__result__
+			}
+		}
+
+		#[cfg(feature = "std")]
+		impl #crate_::sp_wasm_interface::Function for #struct_name {
+			fn name(&self) -> &str {
+				#name
 			}
 
-			&#struct_name as &dyn #crate_::sp_wasm_interface::Function
+			fn signature(&self) -> #crate_::sp_wasm_interface::Signature {
+				#signature
+			}
+
+			fn execute(
+				&self,
+				__function_context__: &mut dyn #crate_::sp_wasm_interface::FunctionContext,
+				args: &mut dyn Iterator<Item = #crate_::sp_wasm_interface::Value>,
+			) -> std::result::Result<Option<#crate_::sp_wasm_interface::Value>, String> {
+				#(#convert_args_dynamic_ffi_to_static_ffi)*
+				let __result__ = Self::call(
+					__function_context__,
+					#(#ffi_names),*
+				)?;
+				#convert_return_value_static_ffi_to_dynamic_ffi
+				__result__
+			}
 		}
-	})
+	};
+
+	let register_body = quote! {
+		registry.register_static(
+			#crate_::sp_wasm_interface::Function::name(&#struct_name),
+			|mut caller: #crate_::sp_wasm_interface::wasmtime::Caller<T::State>, #(#ffi_args_prototype),*|
+				-> std::result::Result<#ffi_return_ty, #crate_::sp_wasm_interface::wasmtime::Trap>
+			{
+				T::with_function_context(caller, move |__function_context__| {
+					#struct_name::call(
+						__function_context__,
+						#(#ffi_names,)*
+					)
+				}).map_err(#crate_::sp_wasm_interface::wasmtime::Trap::new)
+			}
+		)?;
+	};
+
+	Ok((implementation, struct_name, register_body))
 }
 
 /// Generate the `wasm_interface::Signature` for the given host function `sig`.
@@ -260,86 +410,6 @@ fn generate_wasm_interface_signature_for_host_function(sig: &Signature) -> Resul
 	})
 }
 
-/// Generate the code that converts the wasm values given to `HostFunctions::execute` into the FFI
-/// values.
-fn generate_wasm_to_ffi_values<'a>(
-	sig: &'a Signature,
-	trait_name: &'a Ident,
-) -> impl Iterator<Item = Result<TokenStream>> + 'a {
-	let crate_ = generate_crate_access();
-	let function_name = &sig.ident;
-	let error_message = format!(
-		"Number of arguments given to `{}` does not match the expected number of arguments!",
-		function_name,
-	);
-
-	get_function_argument_names_and_types_without_ref(sig).map(move |(name, ty)| {
-		let try_from_error = format!(
-			"Could not instantiate `{}` from wasm value while executing `{}` from interface `{}`!",
-			name.to_token_stream(),
-			function_name,
-			trait_name,
-		);
-
-		let var_name = generate_ffi_value_var_name(&name)?;
-
-		Ok(quote! {
-			let val = args.next().ok_or_else(|| #error_message)?;
-			let #var_name = <
-				<#ty as #crate_::RIType>::FFIType as #crate_::sp_wasm_interface::TryFromValue
-			>::try_from_value(val).ok_or_else(|| #try_from_error)?;
-		})
-	})
-}
-
-/// Generate the code to convert the ffi values on the host to the host values using `FromFFIValue`.
-fn generate_ffi_to_host_value<'a>(
-	sig: &'a Signature,
-) -> impl Iterator<Item = Result<TokenStream>> + 'a {
-	let mut_access = get_function_argument_types_ref_and_mut(sig);
-	let crate_ = generate_crate_access();
-
-	get_function_argument_names_and_types_without_ref(sig)
-		.zip(mut_access.map(|v| v.and_then(|m| m.1)))
-		.map(move |((name, ty), mut_access)| {
-			let ffi_value_var_name = generate_ffi_value_var_name(&name)?;
-
-			Ok(quote! {
-				let #mut_access #name = <#ty as #crate_::host::FromFFIValue>::from_ffi_value(
-					__function_context__,
-					#ffi_value_var_name,
-				)?;
-			})
-		})
-}
-
-/// Generate the code to call the host function and the ident that stores the result.
-fn generate_host_function_call(sig: &Signature, version: u32, is_wasm_only: bool) -> TokenStream {
-	let host_function_name = create_function_ident_with_version(&sig.ident, version);
-	let result_var_name = generate_host_function_result_var_name(&sig.ident);
-	let ref_and_mut =
-		get_function_argument_types_ref_and_mut(sig).map(|ram| ram.map(|(vr, vm)| quote!(#vr #vm)));
-	let names = get_function_argument_names(sig);
-
-	let var_access = names
-		.zip(ref_and_mut)
-		.map(|(n, ref_and_mut)| quote!( #ref_and_mut #n ))
-		// If this is a wasm only interface, we add the function context as last parameter.
-		.chain(
-			iter::from_fn(|| if is_wasm_only { Some(quote!(__function_context__)) } else { None })
-				.take(1),
-		);
-
-	quote! {
-		let #result_var_name = #host_function_name ( #( #var_access ),* );
-	}
-}
-
-/// Generate the variable name that stores the result of the host function.
-fn generate_host_function_result_var_name(name: &Ident) -> Ident {
-	Ident::new(&format!("{}_result", name), Span::call_site())
-}
-
 /// Generate the variable name that stores the FFI value.
 fn generate_ffi_value_var_name(pat: &Pat) -> Result<Ident> {
 	match pat {
@@ -354,49 +424,3 @@ fn generate_ffi_value_var_name(pat: &Pat) -> Result<Ident> {
 		_ => Err(Error::new(pat.span(), "Not supported as variable name!")),
 	}
 }
-
-/// Generate code that copies data from the host back to preallocated wasm memory.
-///
-/// Any argument that is given as `&mut` is interpreted as preallocated memory and it is expected
-/// that the type implements `IntoPreAllocatedFFIValue`.
-fn generate_into_preallocated_ffi_value(sig: &Signature) -> Result<TokenStream> {
-	let crate_ = generate_crate_access();
-	let ref_and_mut = get_function_argument_types_ref_and_mut(sig)
-		.map(|ram| ram.and_then(|(vr, vm)| vm.map(|v| (vr, v))));
-	let names_and_types = get_function_argument_names_and_types_without_ref(sig);
-
-	ref_and_mut
-		.zip(names_and_types)
-		.filter_map(|(ram, (name, ty))| ram.map(|_| (name, ty)))
-		.map(|(name, ty)| {
-			let ffi_var_name = generate_ffi_value_var_name(&name)?;
-
-			Ok(quote! {
-				<#ty as #crate_::host::IntoPreallocatedFFIValue>::into_preallocated_ffi_value(
-					#name,
-					__function_context__,
-					#ffi_var_name,
-				)?;
-			})
-		})
-		.collect()
-}
-
-/// Generate the code that converts the return value into the appropriate wasm value.
-fn generate_return_value_into_wasm_value(sig: &Signature) -> TokenStream {
-	let crate_ = generate_crate_access();
-
-	match &sig.output {
-		ReturnType::Default => quote!(Ok(None)),
-		ReturnType::Type(_, ty) => {
-			let result_var_name = generate_host_function_result_var_name(&sig.ident);
-
-			quote! {
-				<#ty as #crate_::host::IntoFFIValue>::into_ffi_value(
-					#result_var_name,
-					__function_context__,
-				).map(#crate_::sp_wasm_interface::IntoValue::into_value).map(Some)
-			}
-		},
-	}
-}

substrate/primitives/runtime-interface/src/impls.rs

@@ -95,36 +95,36 @@ macro_rules! impl_traits_for_primitives {
 }
 
 impl_traits_for_primitives! {
-	u8, u8,
-	u16, u16,
+	u8, u32,
+	u16, u32,
 	u32, u32,
 	u64, u64,
-	i8, i8,
-	i16, i16,
+	i8, i32,
+	i16, i32,
 	i32, i32,
 	i64, i64,
 }
 
-/// `bool` is passed as `u8`.
+/// `bool` is passed as `u32`.
 ///
 /// - `1`: true
 /// - `0`: false
 impl RIType for bool {
-	type FFIType = u8;
+	type FFIType = u32;
 }
 
 #[cfg(not(feature = "std"))]
 impl IntoFFIValue for bool {
 	type Owned = ();
 
-	fn into_ffi_value(&self) -> WrappedFFIValue<u8> {
+	fn into_ffi_value(&self) -> WrappedFFIValue<u32> {
 		if *self { 1 } else { 0 }.into()
 	}
 }
 
 #[cfg(not(feature = "std"))]
 impl FromFFIValue for bool {
-	fn from_ffi_value(arg: u8) -> bool {
+	fn from_ffi_value(arg: u32) -> bool {
 		arg == 1
 	}
 }
@@ -133,14 +133,14 @@ impl FromFFIValue for bool {
 impl FromFFIValue for bool {
 	type SelfInstance = bool;
 
-	fn from_ffi_value(_: &mut dyn FunctionContext, arg: u8) -> Result<bool> {
+	fn from_ffi_value(_: &mut dyn FunctionContext, arg: u32) -> Result<bool> {
 		Ok(arg == 1)
 	}
 }
 
 #[cfg(feature = "std")]
 impl IntoFFIValue for bool {
-	fn into_ffi_value(self, _: &mut dyn FunctionContext) -> Result<u8> {
+	fn into_ffi_value(self, _: &mut dyn FunctionContext) -> Result<u32> {
 		Ok(if self { 1 } else { 0 })
 	}
 }

substrate/primitives/runtime-interface/src/lib.rs

@@ -80,17 +80,17 @@
 //!
 //! | Type | FFI type | Conversion |
 //! |----|----|----|
-//! | `u8` | `u8` | `Identity` |
-//! | `u16` | `u16` | `Identity` |
+//! | `u8` | `u32` | zero-extended to 32-bits |
+//! | `u16` | `u32` | zero-extended to 32-bits |
 //! | `u32` | `u32` | `Identity` |
 //! | `u64` | `u64` | `Identity` |
 //! | `i128` | `u32` | `v.as_ptr()` (pointer to a 16 byte array) |
-//! | `i8` | `i8` | `Identity` |
-//! | `i16` | `i16` | `Identity` |
+//! | `i8` | `i32` | sign-extended to 32-bits |
+//! | `i16` | `i32` | sign-extended to 32-bits |
 //! | `i32` | `i32` | `Identity` |
 //! | `i64` | `i64` | `Identity` |
 //! | `u128` | `u32` | `v.as_ptr()` (pointer to a 16 byte array) |
-//! | `bool` | `u8` | `if v { 1 } else { 0 }` |
+//! | `bool` | `u32` | `if v { 1 } else { 0 }` |
 //! | `&str` | `u64` | <code>v.len() 32bit << 32 &#124; v.as_ptr() 32bit</code> |
 //! | `&[u8]` | `u64` | <code>v.len() 32bit << 32 &#124; v.as_ptr() 32bit</code> |
 //! | `Vec<u8>` | `u64` | <code>v.len() 32bit << 32 &#124; v.as_ptr() 32bit</code> |
@@ -325,7 +325,9 @@ pub use util::{pack_ptr_and_len, unpack_ptr_and_len};
 pub trait RIType {
 	/// The ffi type that is used to represent `Self`.
 	#[cfg(feature = "std")]
-	type FFIType: sp_wasm_interface::IntoValue + sp_wasm_interface::TryFromValue;
+	type FFIType: sp_wasm_interface::IntoValue
+		+ sp_wasm_interface::TryFromValue
+		+ sp_wasm_interface::WasmTy;
 	#[cfg(not(feature = "std"))]
 	type FFIType;
 }

substrate/primitives/runtime-interface/src/pass_by.rs

@@ -403,11 +403,11 @@ pub struct Enum<T: Copy + Into<u8> + TryFrom<u8>>(PhantomData<T>);
 #[cfg(feature = "std")]
 impl<T: Copy + Into<u8> + TryFrom<u8>> PassByImpl<T> for Enum<T> {
 	fn into_ffi_value(instance: T, _: &mut dyn FunctionContext) -> Result<Self::FFIType> {
-		Ok(instance.into())
+		Ok(instance.into() as u32)
 	}
 
 	fn from_ffi_value(_: &mut dyn FunctionContext, arg: Self::FFIType) -> Result<T> {
-		T::try_from(arg).map_err(|_| format!("Invalid enum discriminant: {}", arg))
+		T::try_from(arg as u8).map_err(|_| format!("Invalid enum discriminant: {}", arg))
 	}
 }
 
@@ -417,17 +417,17 @@ impl<T: Copy + Into<u8> + TryFrom<u8, Error = ()>> PassByImpl<T> for Enum<T> {
 
 	fn into_ffi_value(instance: &T) -> WrappedFFIValue<Self::FFIType, Self::Owned> {
 		let value: u8 = (*instance).into();
-		value.into()
+		(value as u32).into()
 	}
 
 	fn from_ffi_value(arg: Self::FFIType) -> T {
-		T::try_from(arg).expect("Host to wasm provides a valid enum discriminant; qed")
+		T::try_from(arg as u8).expect("Host to wasm provides a valid enum discriminant; qed")
 	}
 }
 
-/// The type is passed as `u8`.
+/// The type is passed as `u32`.
 ///
 /// The value is corresponds to the discriminant of the variant.
 impl<T: Copy + Into<u8> + TryFrom<u8>> RIType for Enum<T> {
-	type FFIType = u8;
+	type FFIType = u32;
 }

substrate/primitives/runtime-interface/test-wasm-deprecated/Cargo.toml

@@ -13,7 +13,7 @@ publish = false
 targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
-sp-runtime-interface = { version = "4.0.0", default-features = false, path = "../" }
+sp-runtime-interface = { version = "4.1.0-dev", default-features = false, path = "../" }
 sp-std = { version = "4.0.0", default-features = false, path = "../../std" }
 sp-io = { version = "4.0.0-dev", default-features = false, path = "../../io" }
 sp-core = { version = "4.1.0-dev", default-features = false, path = "../../core" }

substrate/primitives/runtime-interface/test-wasm/Cargo.toml

@@ -13,7 +13,7 @@ publish = false
 targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
-sp-runtime-interface = { version = "4.0.0", default-features = false, path = "../" }
+sp-runtime-interface = { version = "4.1.0-dev", default-features = false, path = "../" }
 sp-std = { version = "4.0.0", default-features = false, path = "../../std" }
 sp-io = { version = "4.0.0-dev", default-features = false, path = "../../io" }
 sp-core = { version = "4.1.0-dev", default-features = false, path = "../../core" }

substrate/primitives/runtime-interface/test/Cargo.toml

@@ -12,7 +12,7 @@ repository = "https://github.com/paritytech/substrate/"
 targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
-sp-runtime-interface = { version = "4.0.0", path = "../" }
+sp-runtime-interface = { version = "4.1.0-dev", path = "../" }
 sc-executor = { version = "0.10.0-dev", path = "../../../client/executor" }
 sc-executor-common = { version = "0.10.0-dev", path = "../../../client/executor/common" }
 sp-runtime-interface-test-wasm = { version = "2.0.0", path = "../test-wasm" }

substrate/primitives/runtime-interface/test/src/lib.rs

@@ -24,7 +24,7 @@ use sp_runtime_interface_test_wasm::{test_api::HostFunctions, wasm_binary_unwrap
 use sp_runtime_interface_test_wasm_deprecated::wasm_binary_unwrap as wasm_binary_deprecated_unwrap;
 
 use sc_executor_common::runtime_blob::RuntimeBlob;
-use sp_wasm_interface::HostFunctions as HostFunctionsT;
+use sp_wasm_interface::{ExtendedHostFunctions, HostFunctions as HostFunctionsT};
 
 use std::{
 	collections::HashSet,
@@ -39,17 +39,11 @@ fn call_wasm_method_with_result<HF: HostFunctionsT>(
 ) -> Result<TestExternalities, String> {
 	let mut ext = TestExternalities::default();
 	let mut ext_ext = ext.ext();
-	let mut host_functions = HF::host_functions();
-	host_functions.extend(sp_io::SubstrateHostFunctions::host_functions());
 
-	let executor = sc_executor::WasmExecutor::new(
-		sc_executor::WasmExecutionMethod::Interpreted,
-		Some(8),
-		host_functions,
-		8,
-		None,
-		2,
-	);
+	let executor = sc_executor::WasmExecutor::<
+		ExtendedHostFunctions<sp_io::SubstrateHostFunctions, HF>,
+	>::new(sc_executor::WasmExecutionMethod::Interpreted, Some(8), 8, None, 2);
+
 	executor
 		.uncached_call(
 			RuntimeBlob::uncompress_if_needed(binary).expect("Failed to parse binary"),

substrate/primitives/sandbox/Cargo.toml

@@ -23,7 +23,7 @@ wasmi = { version = "0.9.0", optional = true }
 sp-core = { version = "4.1.0-dev", default-features = false, path = "../core" }
 sp-std = { version = "4.0.0", default-features = false, path = "../std" }
 sp-io = { version = "4.0.0-dev", default-features = false, path = "../io" }
-sp-wasm-interface = { version = "4.0.0", default-features = false, path = "../wasm-interface" }
+sp-wasm-interface = { version = "4.1.0-dev", default-features = false, path = "../wasm-interface" }
 codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false }
 log = { version = "0.4", default-features = false }
 

substrate/primitives/tasks/Cargo.toml

@@ -18,7 +18,7 @@ log = { version = "0.4.8", optional = true }
 sp-core = { version = "4.1.0-dev", default-features = false, path = "../core" }
 sp-externalities = { version = "0.10.0", optional = true, path = "../externalities" }
 sp-io = { version = "4.0.0-dev", default-features = false, path = "../io" }
-sp-runtime-interface = { version = "4.0.0", default-features = false, path = "../runtime-interface" }
+sp-runtime-interface = { version = "4.1.0-dev", default-features = false, path = "../runtime-interface" }
 sp-std = { version = "4.0.0", default-features = false, path = "../std" }
 
 [dev-dependencies]

substrate/primitives/wasm-interface/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sp-wasm-interface"
-version = "4.0.0"
+version = "4.1.0-dev"
 authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2021"
 license = "Apache-2.0"
@@ -15,10 +15,12 @@ targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
 wasmi = { version = "0.9.1", optional = true }
+wasmtime = { version = "0.31.0", optional = true, default-features = false }
+log = { version = "0.4.14", optional = true }
 impl-trait-for-tuples = "0.2.1"
 sp-std = { version = "4.0.0", path = "../std", default-features = false }
 codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false, features = ["derive"] }
 
 [features]
 default = [ "std" ]
-std = [ "wasmi", "sp-std/std", "codec/std" ]
+std = [ "wasmi", "sp-std/std", "codec/std", "log" ]

substrate/primitives/wasm-interface/src/lib.rs

@@ -24,6 +24,25 @@ use sp_std::{borrow::Cow, iter::Iterator, marker::PhantomData, mem, result, vec,
 #[cfg(feature = "std")]
 mod wasmi_impl;
 
+#[cfg(not(all(feature = "std", feature = "wasmtime")))]
+#[macro_export]
+macro_rules! if_wasmtime_is_enabled {
+	($($token:tt)*) => {};
+}
+
+#[cfg(all(feature = "std", feature = "wasmtime"))]
+#[macro_export]
+macro_rules! if_wasmtime_is_enabled {
+    ($($token:tt)*) => {
+        $($token)*
+    }
+}
+
+if_wasmtime_is_enabled! {
+	// Reexport wasmtime so that its types are accessible from the procedural macro.
+	pub use wasmtime;
+}
+
 /// Result type used by traits in this crate.
 #[cfg(feature = "std")]
 pub type Result<T> = result::Result<T, String>;
@@ -105,7 +124,8 @@ impl Value {
 	}
 }
 
-/// Provides `Sealed` trait to prevent implementing trait `PointerType` outside of this crate.
+/// Provides `Sealed` trait to prevent implementing trait `PointerType` and `WasmTy` outside of this
+/// crate.
 mod private {
 	pub trait Sealed {}
 
@@ -113,6 +133,9 @@ mod private {
 	impl Sealed for u16 {}
 	impl Sealed for u32 {}
 	impl Sealed for u64 {}
+
+	impl Sealed for i32 {}
+	impl Sealed for i64 {}
 }
 
 /// Something that can be wrapped in a wasm `Pointer`.
@@ -338,10 +361,48 @@ pub trait Sandbox {
 	fn get_global_val(&self, instance_idx: u32, name: &str) -> Result<Option<Value>>;
 }
 
+if_wasmtime_is_enabled! {
+	/// A trait used to statically register host callbacks with the WASM executor,
+	/// so that they call be called from within the runtime with minimal overhead.
+	///
+	/// This is used internally to interface the wasmtime-based executor with the
+	/// host functions' definitions generated through the runtime interface macro,
+	/// and is not meant to be used directly.
+	pub trait HostFunctionRegistry {
+		type State;
+		type Error;
+		type FunctionContext: FunctionContext;
+
+		/// Wraps the given `caller` in a type which implements `FunctionContext`
+		/// and calls the given `callback`.
+		fn with_function_context<R>(
+			caller: wasmtime::Caller<Self::State>,
+			callback: impl FnOnce(&mut dyn FunctionContext) -> R,
+		) -> R;
+
+		/// Registers a given host function with the WASM executor.
+		///
+		/// The function has to be statically callable, and all of its arguments
+		/// and its return value have to be compatible with WASM FFI.
+		fn register_static<Params, Results>(
+			&mut self,
+			fn_name: &str,
+			func: impl wasmtime::IntoFunc<Self::State, Params, Results> + 'static,
+		) -> core::result::Result<(), Self::Error>;
+	}
+}
+
 /// Something that provides implementations for host functions.
-pub trait HostFunctions: 'static {
+pub trait HostFunctions: 'static + Send + Sync {
 	/// Returns the host functions `Self` provides.
 	fn host_functions() -> Vec<&'static dyn Function>;
+
+	if_wasmtime_is_enabled! {
+		/// Statically registers the host functions.
+		fn register_static<T>(registry: &mut T) -> core::result::Result<(), T::Error>
+		where
+			T: HostFunctionRegistry;
+	}
 }
 
 #[impl_trait_for_tuples::impl_for_tuples(30)]
@@ -353,8 +414,146 @@ impl HostFunctions for Tuple {
 
 		host_functions
 	}
+
+	#[cfg(all(feature = "std", feature = "wasmtime"))]
+	fn register_static<T>(registry: &mut T) -> core::result::Result<(), T::Error>
+	where
+		T: HostFunctionRegistry,
+	{
+		for_tuples!(
+			#( Tuple::register_static(registry)?; )*
+		);
+
+		Ok(())
+	}
 }
 
+/// A wrapper which merges two sets of host functions, and allows the second set to override
+/// the host functions from the first set.
+pub struct ExtendedHostFunctions<Base, Overlay> {
+	phantom: PhantomData<(Base, Overlay)>,
+}
+
+impl<Base, Overlay> HostFunctions for ExtendedHostFunctions<Base, Overlay>
+where
+	Base: HostFunctions,
+	Overlay: HostFunctions,
+{
+	fn host_functions() -> Vec<&'static dyn Function> {
+		let mut base = Base::host_functions();
+		let overlay = Overlay::host_functions();
+		base.retain(|host_fn| {
+			!overlay.iter().any(|ext_host_fn| host_fn.name() == ext_host_fn.name())
+		});
+		base.extend(overlay);
+		base
+	}
+
+	if_wasmtime_is_enabled! {
+		fn register_static<T>(registry: &mut T) -> core::result::Result<(), T::Error>
+		where
+			T: HostFunctionRegistry,
+		{
+			struct Proxy<'a, T> {
+				registry: &'a mut T,
+				seen_overlay: std::collections::HashSet<String>,
+				seen_base: std::collections::HashSet<String>,
+				overlay_registered: bool,
+			}
+
+			impl<'a, T> HostFunctionRegistry for Proxy<'a, T>
+			where
+				T: HostFunctionRegistry,
+			{
+				type State = T::State;
+				type Error = T::Error;
+				type FunctionContext = T::FunctionContext;
+
+				fn with_function_context<R>(
+					caller: wasmtime::Caller<Self::State>,
+					callback: impl FnOnce(&mut dyn FunctionContext) -> R,
+				) -> R {
+					T::with_function_context(caller, callback)
+				}
+
+				fn register_static<Params, Results>(
+					&mut self,
+					fn_name: &str,
+					func: impl wasmtime::IntoFunc<Self::State, Params, Results> + 'static,
+				) -> core::result::Result<(), Self::Error> {
+					if self.overlay_registered {
+						if !self.seen_base.insert(fn_name.to_owned()) {
+							log::warn!(
+								target: "extended_host_functions",
+								"Duplicate base host function: '{}'",
+								fn_name,
+							);
+
+							// TODO: Return an error here?
+							return Ok(())
+						}
+
+						if self.seen_overlay.contains(fn_name) {
+							// Was already registered when we went through the overlay, so just ignore it.
+							log::debug!(
+								target: "extended_host_functions",
+								"Overriding base host function: '{}'",
+								fn_name,
+							);
+
+							return Ok(())
+						}
+					} else if !self.seen_overlay.insert(fn_name.to_owned()) {
+						log::warn!(
+							target: "extended_host_functions",
+							"Duplicate overlay host function: '{}'",
+							fn_name,
+						);
+
+						// TODO: Return an error here?
+						return Ok(())
+					}
+
+					self.registry.register_static(fn_name, func)
+				}
+			}
+
+			let mut proxy = Proxy {
+				registry,
+				seen_overlay: Default::default(),
+				seen_base: Default::default(),
+				overlay_registered: false,
+			};
+
+			// The functions from the `Overlay` can override those from the `Base`,
+			// so `Overlay` is registered first, and then we skip those functions
+			// in `Base` if they were already registered from the `Overlay`.
+			Overlay::register_static(&mut proxy)?;
+			proxy.overlay_registered = true;
+			Base::register_static(&mut proxy)?;
+
+			Ok(())
+		}
+	}
+}
+
+/// A trait for types directly usable at the WASM FFI boundary without any conversion at all.
+///
+/// This trait is sealed and should not be implemented downstream.
+#[cfg(all(feature = "std", feature = "wasmtime"))]
+pub trait WasmTy: wasmtime::WasmTy + private::Sealed {}
+
+/// A trait for types directly usable at the WASM FFI boundary without any conversion at all.
+///
+/// This trait is sealed and should not be implemented downstream.
+#[cfg(not(all(feature = "std", feature = "wasmtime")))]
+pub trait WasmTy: private::Sealed {}
+
+impl WasmTy for i32 {}
+impl WasmTy for u32 {}
+impl WasmTy for i64 {}
+impl WasmTy for u64 {}
+
 /// Something that can be converted into a wasm compatible `Value`.
 pub trait IntoValue {
 	/// The type of the value in wasm.