experiment: mechanism for interacting with external Wasm components

rts/motoko-rts/src/component.rs

@@ -0,0 +1,57 @@
+// Wasm Component Model utilities
+
+use crate::{
+    barriers::allocation_barrier,
+    memory::{alloc_blob, Memory},
+    types::Value,
+    Bytes,
+};
+use alloc as alloc_crate;
+use core::convert::TryInto;
+use motoko_rts_macros::ic_mem_fn;
+
+/// Convert a Canonical ABI `list<u8>` pointer to a Motoko `Blob`.
+#[ic_mem_fn]
+unsafe fn blob_of_cabi<M: Memory>(mem: &mut M, ret: *const usize) -> Value {
+    let content = *ret as *const u8;
+    let len = *ret.add(1);
+
+    // TODO: reuse Blob from `cabi_realloc`?
+    let value = alloc_blob(mem, Bytes(len.try_into().unwrap())); // Checked conversion from `usize` to `u32`
+    let blob = value.as_blob_mut();
+    let dest = blob.payload_addr();
+    for i in 0..len as usize {
+        *dest.add(i) = *content.add(i);
+    }
+    allocation_barrier(value)
+}
+
+/// Canonical ABI allocation logic.
+/// Derived from: https://docs.rs/wit-bindgen-rt/0.27.0/src/wit_bindgen_rt/lib.rs.html#54-88
+#[ic_mem_fn]
+unsafe fn cabi_realloc<M: Memory>(
+    _mem: &mut M,
+    old_ptr: *mut u8,
+    old_len: usize,
+    align: usize,
+    new_len: usize,
+) -> *mut u8 {
+    use alloc_crate::alloc::{self, Layout};
+
+    let layout;
+    let ptr = if old_len == 0 {
+        if new_len == 0 {
+            return align as *mut u8;
+        }
+        layout = Layout::from_size_align_unchecked(new_len, align);
+        alloc::alloc(layout)
+    } else {
+        debug_assert_ne!(new_len, 0, "non-zero old_len requires non-zero new_len!");
+        layout = Layout::from_size_align_unchecked(old_len, align);
+        alloc::realloc(old_ptr, layout, new_len)
+    };
+    if ptr.is_null() {
+        unreachable!();
+    }
+    ptr
+}

rts/motoko-rts/src/lib.rs

@@ -26,6 +26,7 @@ pub mod bitrel;
 mod blob_iter;
 pub mod buf;
 mod char;
+mod component;
 pub mod constants;
 pub mod continuation_table;
 #[cfg(feature = "ic")]

src/codegen/compile.ml

@@ -1259,6 +1259,9 @@ module RTS = struct
     E.add_func_import env "rts" "stream_shutdown" [I32Type] [];
     E.add_func_import env "rts" "stream_reserve" [I32Type; I32Type] [I32Type];
     E.add_func_import env "rts" "stream_stable_dest" [I32Type; I64Type; I64Type] [];
+    if !Flags.import_component then (
+      E.add_func_import env "rts" "blob_of_cabi" [I32Type] [I32Type];
+      E.add_func_import env "rts" "cabi_realloc" [I32Type; I32Type; I32Type; I32Type] [I32Type]);
     if !Flags.gc_strategy = Flags.Incremental then
       incremental_gc_imports env
     else
@@ -11257,6 +11260,24 @@ and compile_prim_invocation (env : E.t) ae p es at =
     compile_exp_as env ae SR.UnboxedFloat64 e ^^
     E.call_import env "rts" "log" (* musl *)
 
+  | OtherPrim "wit:component:call", [e] ->
+    assert !Flags.import_component;
+    SR.Vanilla,
+    (* Read blob pointer and length *)
+    let set_blob, get_blob = new_local env "blob" in
+    compile_exp_as env ae SR.Vanilla e ^^ set_blob ^^
+    (* Allocate return value *)
+    let set_ret, get_ret = new_local env "ret" in
+    (* TODO: optimize? *)
+    Blob.lit env "\x00\x00\x00\x00\x00\x00\x00\x00" ^^ set_ret ^^ (* pointer, length *)
+    (* Call component export *)
+    get_blob ^^ Blob.payload_ptr_unskewed env ^^
+    get_blob ^^ Blob.len env ^^
+    get_ret ^^ Blob.payload_ptr_unskewed env ^^
+    E.call_import env "component" "call" ^^
+    get_ret ^^ Blob.payload_ptr_unskewed env ^^
+    E.call_import env "rts" "blob_of_cabi"
+
   (* Other prims, nullary *)
 
   | SystemTimePrim, [] ->
@@ -12830,6 +12851,10 @@ let compile mode rts (prog : Ir.prog) : Wasm_exts.CustomModule.extended_module =
   IC.system_imports env;
   RTS.system_imports env;
 
+  (* Wasm Component Model *)
+  if !Flags.import_component then
+    E.add_func_import env "component" "call" [I32Type; I32Type; I32Type] [];
+
   compile_init_func env prog;
   let start_fi_o = match E.mode env with
     | Flags.ICMode | Flags.RefMode ->

src/exes/moc.ml

@@ -109,6 +109,9 @@ let argspec = [
   "-wasi-system-api",
     Arg.Unit (fun () -> Flags.(compile_mode := WASIMode)),
       " use the WASI system API (wasmtime)";
+  "-import-component",
+    Arg.Unit (fun () -> Flags.(import_component := true)),
+      " enable calling an external Wasm component";
   "-ref-system-api",
   Arg.Unit (fun () -> Flags.(compile_mode := RefMode)),
       " use the reference implementation of the Internet Computer system API (ic-ref-run)";

src/lang_utils/error_codes.ml

@@ -203,4 +203,5 @@ let error_codes : (string * string option) list =
     "M0197", Some([%blob "lang_utils/error_codes/M0197.md"]); (* `system` capability required *)
     "M0198", Some([%blob "lang_utils/error_codes/M0198.md"]); (* Unused field pattern warning *)
     "M0199", Some([%blob "lang_utils/error_codes/M0199.md"]); (* Deprecate experimental stable memory *)
+    "M0200", Some([%blob "lang_utils/error_codes/M0200.md"]); (* Component import is unavailable *)
   ]

src/lang_utils/error_codes/M0200.md

@@ -0,0 +1,5 @@
+# M0200
+
+This error indicates that the Wasm Component Model (cross-language) functionality is not enabled. 
+
+You can fix this by passing the `-import-component` compiler flag, e.g. `moc -wasi-system-api -import-component ...`.

src/linking/linkModule.ml

@@ -258,6 +258,7 @@ let remove_non_ic_exports (em : extended_module) : extended_module =
    exported in the final module *)
   let is_ic_export (exp : export) =
     Lib.String.chop_prefix "canister_" (Lib.Utf8.encode exp.it.name) <> None ||
+    (!Mo_config.Flags.import_component && Lib.String.chop_prefix "cabi_" (Lib.Utf8.encode exp.it.name) <> None) || (* Wasm Component Model *)
     "_start" = Lib.Utf8.encode exp.it.name
   in
 

src/mo_config/flags.ml

@@ -52,3 +52,4 @@ let use_stable_regions = ref false
 let share_code = ref false
 let experimental_stable_memory_default = 0 (* _ < 0: error; _ = 0: warn, _ > 0: allow *)
 let experimental_stable_memory = ref experimental_stable_memory_default
+let import_component = ref false

src/mo_frontend/typing.ml

@@ -162,7 +162,10 @@ let check_deprecation env at desc id depr =
        | _ -> fun _ _ _ _ -> ())
        env at code
        "this code is (or uses) the deprecated library `ExperimentalStableMemory`.\nPlease use the `Region` library instead: https://internetcomputer.org/docs/current/motoko/main/stable-memory/stable-regions/#the-region-library or compile with flag `--experimental-stable-memory 1` to suppress this message."
-    end
+      end
+  | Some ("M0200" as code) ->
+    if not !Flags.import_component then
+      error env at code "component import is unavailable (pass `-import-component` flag)"
   | Some msg ->
     warn env at "M0154" "%s %s is deprecated:\n%s" desc id msg
   | None -> ()

src/prelude/prim.mo

@@ -267,6 +267,11 @@ func arctan2(y : Float, x : Float) : Float = (prim "fatan2" : (Float, Float) ->
 func exp(f : Float) : Float = (prim "fexp" : Float -> Float) f;
 func log(f : Float) : Float = (prim "flog" : Float -> Float) f;
 
+// Wasm Component Model functions
+
+/// @deprecated M0200
+func componentCall(value : Blob) : Blob = (prim "wit:component:call" : Blob -> Blob) value;
+
 // Array utilities
 
 func Array_init<T>(len : Nat, x : T) : [var T] {

test/bench/ok/heap-32.drun-run-opt.ok

@@ -1,5 +1,5 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
 debug.print: (50_227, +29_863_068, 708_174_952)
-debug.print: (50_070, +32_992_212, 766_613_680)
+debug.print: (50_070, +32_992_212, 766_613_760)
 ingress Completed: Reply: 0x4449444c0000

test/bench/ok/heap-32.drun-run.ok

@@ -1,5 +1,5 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
 debug.print: (50_227, +29_863_068, 769_000_085)
-debug.print: (50_070, +32_992_212, 830_427_376)
+debug.print: (50_070, +32_992_212, 830_427_500)
 ingress Completed: Reply: 0x4449444c0000

test/fail/M0200.mo

@@ -0,0 +1,3 @@
+import Prim = "mo:⛔";
+
+ignore Prim.componentCall(123);

test/fail/ok/M0200.tc.ok

@@ -0,0 +1 @@
+M0200.mo:3.8-3.26: type error [M0200], component import is unavailable (pass `-import-component` flag)

test/fail/ok/M0200.tc.ret.ok

@@ -0,0 +1 @@
+Return code 1

test/fail/ok/no-timer-canc.tc.ok

@@ -74,6 +74,7 @@ no-timer-canc.mo:3.10-3.21: type error [M0119], object field cancelTimer is not
     clzNat32 : Nat32 -> Nat32;
     clzNat64 : Nat64 -> Nat64;
     clzNat8 : Nat8 -> Nat8;
+    componentCall : Blob -> Blob;
     cos : Float -> Float;
     createActor : (Blob, Blob) -> async Principal;
     ctzInt16 : Int16 -> Int16;

test/fail/ok/no-timer-set.tc.ok

@@ -74,6 +74,7 @@ no-timer-set.mo:3.10-3.18: type error [M0119], object field setTimer is not cont
     clzNat32 : Nat32 -> Nat32;
     clzNat64 : Nat64 -> Nat64;
     clzNat8 : Nat8 -> Nat8;
+    componentCall : Blob -> Blob;
     cos : Float -> Float;
     createActor : (Blob, Blob) -> async Principal;
     ctzInt16 : Int16 -> Int16;