wasi: use WasmMemoryObject handle for perf

Author: devsnek

lib/wasi.js

@@ -10,14 +10,12 @@ const {
 } = primordials;
 
 const {
-  ERR_INVALID_ARG_TYPE,
   ERR_WASI_ALREADY_STARTED
 } = require('internal/errors').codes;
 const {
   emitExperimentalWarning,
   kEmptyObject,
 } = require('internal/util');
-const { isArrayBuffer } = require('internal/util/types');
 const {
   validateArray,
   validateBoolean,
@@ -39,20 +37,6 @@ function setupInstance(self, instance) {
   validateObject(instance, 'instance');
   validateObject(instance.exports, 'instance.exports');
 
-  // WASI::_SetMemory() in src/node_wasi.cc only expects that |memory| is
-  // an object. It will try to look up the .buffer property when needed
-  // and fail with UVWASI_EINVAL when the property is missing or is not
-  // an ArrayBuffer. Long story short, we don't need much validation here
-  // but we type-check anyway because it helps catch bugs in the user's
-  // code early.
-  validateObject(instance.exports.memory, 'instance.exports.memory');
-  if (!isArrayBuffer(instance.exports.memory.buffer)) {
-    throw new ERR_INVALID_ARG_TYPE(
-      'instance.exports.memory.buffer',
-      ['WebAssembly.Memory'],
-      instance.exports.memory.buffer);
-  }
-
   self[kInstance] = instance;
   self[kSetMemory](instance.exports.memory);
 }

src/node_wasi.cc

@@ -89,7 +89,7 @@ using v8::Object;
 using v8::String;
 using v8::Uint32;
 using v8::Value;
-
+using v8::WasmMemoryObject;
 
 static MaybeLocal<Value> WASIException(Local<Context> context,
                                        int errorno,
@@ -1643,25 +1643,20 @@ void WASI::SockShutdown(const FunctionCallbackInfo<Value>& args) {
 void WASI::_SetMemory(const FunctionCallbackInfo<Value>& args) {
   WASI* wasi;
   CHECK_EQ(args.Length(), 1);
-  CHECK(args[0]->IsObject());
+  if (!args[0]->IsWasmMemoryObject()) {
+    return node::THROW_ERR_INVALID_ARG_TYPE(
+        env, "instance.exports.memory must be a WebAssembly.Memory object");
+  }
   ASSIGN_OR_RETURN_UNWRAP(&wasi, args.This());
-  wasi->memory_.Reset(wasi->env()->isolate(), args[0].As<Object>());
+  wasi->memory_.Reset(wasi->env()->isolate(), args[0].As<WasmMemoryObject>());
 }
 
 
 uvwasi_errno_t WASI::backingStore(char** store, size_t* byte_length) {
   Environment* env = this->env();
-  Local<Object> memory = PersistentToLocal::Strong(this->memory_);
-  Local<Value> prop;
-
-  if (!memory->Get(env->context(), env->buffer_string()).ToLocal(&prop))
-    return UVWASI_EINVAL;
-
-  if (!prop->IsArrayBuffer())
-    return UVWASI_EINVAL;
-
-  Local<ArrayBuffer> ab = prop.As<ArrayBuffer>();
-  std::shared_ptr<BackingStore> backing_store = ab->GetBackingStore();
+  Local<WasmMemoryObject> memory = PersistentToLocal::Strong(this->memory_);
+  std::shared_ptr<BackingStore> backing_store =
+      memory->Buffer()->GetBackingStore();
   *byte_length = backing_store->ByteLength();
   *store = static_cast<char*>(backing_store->Data());
   CHECK_NOT_NULL(*store);

src/node_wasi.h

@@ -94,7 +94,7 @@ class WASI : public BaseObject,
   inline void writeUInt64(char* memory, uint64_t value, uint32_t offset);
   uvwasi_errno_t backingStore(char** store, size_t* byte_length);
   uvwasi_t uvw_;
-  v8::Global<v8::Object> memory_;
+  v8::Global<v8::WasmMemoryObject> memory_;
   uvwasi_mem_t alloc_info_;
   size_t current_uvwasi_memory_ = 0;
 };