LibWasm+LibWeb: Partially resolve memory exports

This allows the JS side to access the wasm memory, assuming it's
exported by the module.
This can be used to draw stuff on the wasm side and display them from
the js side, for example :^)

Userland/Libraries/LibWasm/AbstractMachine/Interpreter.cpp

@@ -14,10 +14,19 @@
 
 namespace Wasm {
 
-#define TRAP_IF_NOT(x)      \
-    do {                    \
-        if (trap_if_not(x)) \
-            return;         \
+#define TRAP_IF_NOT(x)                                                                         \
+    do {                                                                                       \
+        if (trap_if_not(x)) {                                                                  \
+            dbgln_if(WASM_TRACE_DEBUG, "Trapped because {} failed, at line {}", #x, __LINE__); \
+            return;                                                                            \
+        }                                                                                      \
+    } while (false)
+
+#define TRAP_IF_NOT_NORETURN(x)                                                                \
+    do {                                                                                       \
+        if (trap_if_not(x)) {                                                                  \
+            dbgln_if(WASM_TRACE_DEBUG, "Trapped because {} failed, at line {}", #x, __LINE__); \
+        }                                                                                      \
     } while (false)
 
 void Interpreter::interpret(Configuration& configuration)
@@ -56,9 +65,8 @@ void Interpreter::branch_to_label(Configuration& configuration, LabelIndex index
         configuration.stack().pop();
     }
 
-    // Push results in reverse
-    for (size_t i = results.size(); i > 0; --i)
-        configuration.stack().push(move(static_cast<Vector<NonnullOwnPtr<Value>>&>(results)[i - 1]));
+    for (auto& result : results)
+        configuration.stack().push(move(result));
 
     configuration.ip() = label->continuation();
 }
@@ -269,13 +277,12 @@ struct ConvertToRaw<double> {
 Vector<NonnullOwnPtr<Value>> Interpreter::pop_values(Configuration& configuration, size_t count)
 {
     Vector<NonnullOwnPtr<Value>> results;
-    // Pop results in order
     for (size_t i = 0; i < count; ++i) {
         auto top_of_stack = configuration.stack().pop();
         if (auto value = top_of_stack.get_pointer<NonnullOwnPtr<Value>>())
-            results.append(move(*value));
+            results.prepend(move(*value));
         else
-            trap_if_not(value);
+            TRAP_IF_NOT_NORETURN(value);
     }
     return results;
 }
@@ -361,9 +368,8 @@ void Interpreter::interpret(Configuration& configuration, InstructionPointer& ip
                 break;
         }
 
-        // Push results in reverse
-        for (size_t i = 1; i < results.size() + 1; ++i)
-            configuration.stack().push(move(static_cast<Vector<NonnullOwnPtr<Value>>&>(results)[results.size() - i]));
+        for (auto& result : results)
+            configuration.stack().push(move(result));
 
         if (instruction.opcode() == Instructions::structured_end)
             return;

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -222,6 +222,7 @@ set(SOURCES
     UIEvents/MouseEvent.cpp
     URLEncoder.cpp
     WebAssembly/WebAssemblyObject.cpp
+    WebAssembly/WebAssemblyObjectPrototype.cpp
     WebContentClient.cpp
     XHR/EventNames.cpp
     XHR/XMLHttpRequest.cpp

Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.cpp

@@ -4,11 +4,13 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ScopeGuard.h>
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/ArrayBuffer.h>
 #include <LibJS/Runtime/BigInt.h>
 #include <LibJS/Runtime/TypedArray.h>
 #include <LibWasm/AbstractMachine/Interpreter.h>
+#include <LibWeb/Bindings/WindowObject.h>
 #include <LibWeb/WebAssembly/WebAssemblyObject.h>
 
 namespace Web::Bindings {
@@ -57,6 +59,11 @@ static Result<size_t, JS::Value> parse_module(JS::GlobalObject& global_object, J
     }
     InputMemoryStream stream { *bytes };
     auto module_result = Wasm::Module::parse(stream);
+    ScopeGuard drain_errors {
+        [&] {
+            stream.handle_any_error();
+        }
+    };
     if (module_result.is_error()) {
         // FIXME: Throw CompileError instead.
         auto error = JS::TypeError::create(global_object, Wasm::parse_error_to_string(module_result.error()));
@@ -192,7 +199,11 @@ JS_DEFINE_NATIVE_FUNCTION(WebAssemblyObject::instantiate)
                 },
                 [&](const auto&) {
                     // FIXME: Implement these.
+                    dbgln("Unimplemented import of non-function attempted");
+                    vm.throw_exception<JS::TypeError>(global_object, "LinkError: Not Implemented");
                 });
+            if (vm.exception())
+                break;
         }
 
         if (take_exception_and_reject_if_needed())
@@ -231,7 +242,7 @@ WebAssemblyModuleObject::WebAssemblyModuleObject(JS::GlobalObject& global_object
 }
 
 WebAssemblyInstanceObject::WebAssemblyInstanceObject(JS::GlobalObject& global_object, size_t index)
-    : Object(*global_object.object_prototype())
+    : Object(static_cast<WindowObject&>(global_object).ensure_web_prototype<WebAssemblyInstancePrototype>(class_name()))
     , m_index(index)
 {
 }
@@ -341,12 +352,6 @@ JS::NativeFunction* create_native_function(Wasm::FunctionAddress address, String
         });
 }
 
-void WebAssemblyInstancePrototype::initialize(JS::GlobalObject& global_object)
-{
-    Object::initialize(global_object);
-    define_native_property("exports", exports_getter, nullptr);
-}
-
 void WebAssemblyInstanceObject::initialize(JS::GlobalObject& global_object)
 {
     Object::initialize(global_object);
@@ -361,6 +366,11 @@ void WebAssemblyInstanceObject::initialize(JS::GlobalObject& global_object)
                 auto function = create_native_function(address, export_.name(), global_object);
                 m_exports_object->define_property(export_.name(), function);
             },
+            [&](const Wasm::MemoryAddress& address) {
+                // FIXME: Cache this.
+                auto memory = heap().allocate<WebAssemblyMemoryObject>(global_object, global_object, address);
+                m_exports_object->define_property(export_.name(), memory);
+            },
             [&](const auto&) {
                 // FIXME: Implement other exports!
             });
@@ -369,24 +379,64 @@ void WebAssemblyInstanceObject::initialize(JS::GlobalObject& global_object)
     m_exports_object->set_integrity_level(IntegrityLevel::Frozen);
 }
 
-JS_DEFINE_NATIVE_GETTER(WebAssemblyInstancePrototype::exports_getter)
+void WebAssemblyInstanceObject::visit_edges(Cell::Visitor& visitor)
+{
+    Object::visit_edges(visitor);
+    visitor.visit(m_exports_object);
+}
+
+WebAssemblyMemoryObject::WebAssemblyMemoryObject(JS::GlobalObject& global_object, Wasm::MemoryAddress address)
+    : JS::Object(global_object)
+    , m_address(address)
 {
-    auto this_value = vm.this_value(global_object);
-    auto this_object = this_value.to_object(global_object);
+}
+
+void WebAssemblyMemoryObject::initialize(JS::GlobalObject& global_object)
+{
+    Object::initialize(global_object);
+    define_native_function("grow", grow, 1);
+    define_native_property("buffer", buffer, nullptr);
+}
+
+JS_DEFINE_NATIVE_FUNCTION(WebAssemblyMemoryObject::grow)
+{
+    auto page_count = vm.argument(0).to_u32(global_object);
     if (vm.exception())
         return {};
-    if (!is<WebAssemblyInstanceObject>(this_object)) {
-        vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotAn, "WebAssemblyInstance");
+    auto* this_object = vm.this_value(global_object).to_object(global_object);
+    if (!this_object || !is<WebAssemblyMemoryObject>(this_object)) {
+        vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotA, "Memory");
+        return {};
+    }
+    auto* memory_object = static_cast<WebAssemblyMemoryObject*>(this_object);
+    auto address = memory_object->m_address;
+    auto* memory = WebAssemblyObject::s_abstract_machine.store().get(address);
+    if (!memory)
+        return JS::js_undefined();
+
+    auto previous_size = memory->size() / Wasm::Constants::page_size;
+    if (!memory->grow(page_count * Wasm::Constants::page_size)) {
+        vm.throw_exception<JS::TypeError>(global_object, "Memory.grow() grows past the stated limit of the memory instance");
         return {};
     }
-    auto object = static_cast<WebAssemblyInstanceObject*>(this_object);
-    return object->m_exports_object;
+
+    return JS::Value(static_cast<u32>(previous_size));
 }
 
-void WebAssemblyInstanceObject::visit_edges(Cell::Visitor& visitor)
+JS_DEFINE_NATIVE_GETTER(WebAssemblyMemoryObject::buffer)
 {
-    Object::visit_edges(visitor);
-    visitor.visit(m_exports_object);
+    auto* this_object = vm.this_value(global_object).to_object(global_object);
+    if (!this_object || !is<WebAssemblyMemoryObject>(this_object)) {
+        vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotA, "Memory");
+        return {};
+    }
+    auto* memory_object = static_cast<WebAssemblyMemoryObject*>(this_object);
+    auto address = memory_object->m_address;
+    auto* memory = WebAssemblyObject::s_abstract_machine.store().get(address);
+    if (!memory)
+        return JS::js_undefined();
+
+    return JS::ArrayBuffer::create(global_object, &memory->data());
 }
 
 }

Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObject.h

@@ -9,6 +9,7 @@
 #include <LibJS/Runtime/Object.h>
 #include <LibWasm/AbstractMachine/AbstractMachine.h>
 #include <LibWeb/Forward.h>
+#include <LibWeb/WebAssembly/WebAssemblyObjectPrototype.h>
 
 namespace Web::Bindings {
 
@@ -58,21 +59,6 @@ private:
     size_t m_index { 0 };
 };
 
-class WebAssemblyInstancePrototype final : public JS::Object {
-    JS_OBJECT(WebAssemblyInstancePrototype, JS::Object);
-
-public:
-    explicit WebAssemblyInstancePrototype(JS::GlobalObject& global_object)
-        : JS::Object(global_object)
-    {
-    }
-
-    virtual void initialize(JS::GlobalObject&) override;
-
-private:
-    JS_DECLARE_NATIVE_GETTER(exports_getter);
-};
-
 class WebAssemblyInstanceObject final : public JS::Object {
     JS_OBJECT(WebAssemblyInstanceObject, JS::Object);
 
@@ -93,4 +79,21 @@ private:
     JS::Object* m_exports_object { nullptr };
 };
 
+class WebAssemblyMemoryObject final : public JS::Object {
+    JS_OBJECT(WebAssemblyModuleObject, JS::Object);
+
+public:
+    explicit WebAssemblyMemoryObject(JS::GlobalObject&, Wasm::MemoryAddress);
+    virtual void initialize(JS::GlobalObject&) override;
+    virtual ~WebAssemblyMemoryObject() override = default;
+
+    auto address() const { return m_address; }
+
+private:
+    JS_DECLARE_NATIVE_FUNCTION(grow);
+    JS_DECLARE_NATIVE_GETTER(buffer);
+
+    Wasm::MemoryAddress m_address;
+};
+
 }

Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObjectPrototype.cpp

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/WebAssembly/WebAssemblyObject.h>
+#include <LibWeb/WebAssembly/WebAssemblyObjectPrototype.h>
+
+namespace Web::Bindings {
+
+void WebAssemblyInstancePrototype::initialize(JS::GlobalObject& global_object)
+{
+    Object::initialize(global_object);
+    define_native_property("exports", exports_getter, nullptr);
+}
+
+JS_DEFINE_NATIVE_GETTER(WebAssemblyInstancePrototype::exports_getter)
+{
+    auto this_value = vm.this_value(global_object);
+    auto this_object = this_value.to_object(global_object);
+    if (vm.exception())
+        return {};
+    if (!is<WebAssemblyInstanceObject>(this_object)) {
+        vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotAn, "WebAssemblyInstance");
+        return {};
+    }
+    auto object = static_cast<WebAssemblyInstanceObject*>(this_object);
+    return object->m_exports_object;
+}
+
+}

Userland/Libraries/LibWeb/WebAssembly/WebAssemblyObjectPrototype.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Object.h>
+#include <LibJS/Runtime/VM.h>
+#include <LibWeb/Forward.h>
+
+namespace Web::Bindings {
+
+class WebAssemblyInstancePrototype final : public JS::Object {
+    JS_OBJECT(WebAssemblyInstancePrototype, JS::Object);
+
+public:
+    explicit WebAssemblyInstancePrototype(JS::GlobalObject& global_object)
+        : JS::Object(global_object)
+    {
+    }
+
+    virtual void initialize(JS::GlobalObject&) override;
+
+private:
+    JS_DECLARE_NATIVE_GETTER(exports_getter);
+    static JS::Handle<WebAssemblyInstancePrototype> s_instance;
+};
+
+}