[wasm] Store signature with {WebAssembly.Function} objects.

This adds simple serialization and deserialization of the signature
provided when a {WebAssembly.Function} object is constructed. For now
this signature is only used by the {WebAssembly.Function.type} method,
but will soon be used when importing such functions as well.

R=jkummerow@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: If4a687ea537d8c12f4f01a7d3ac5a795ceb999c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1632211Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61898}

src/builtins/base.tq

@@ -878,7 +878,12 @@ extern class WasmExportedFunctionData extends Struct {
   function_index: Smi;
 }
 
-extern class WasmJSFunctionData extends Struct { wrapper_code: Code; }
+extern class WasmJSFunctionData extends Struct {
+  wrapper_code: Code;
+  serialized_return_count: Smi;
+  serialized_parameter_count: Smi;
+  serialized_signature: ByteArray;  // PodArray<wasm::ValueType>
+}
 
 extern class WasmCapiFunctionData extends Struct {
   call_target: RawPtr;

src/objects/fixed-array.h

@@ -552,9 +552,9 @@ class PodArray : public ByteArray {
   static Handle<PodArray<T>> New(
       Isolate* isolate, int length,
       AllocationType allocation = AllocationType::kYoung);
-  void copy_out(int index, T* result) {
+  void copy_out(int index, T* result, int length) {
     ByteArray::copy_out(index * sizeof(T), reinterpret_cast<byte*>(result),
-                        sizeof(T));
+                        length * sizeof(T));
   }
 
   void copy_in(int index, const T* buffer, int length) {
@@ -564,7 +564,7 @@ class PodArray : public ByteArray {
 
   T get(int index) {
     T result;
-    copy_out(index, &result);
+    copy_out(index, &result, 1);
     return result;
   }
 

src/wasm/wasm-js.cc

@@ -1437,7 +1437,7 @@ void WebAssemblyFunction(const v8::FunctionCallbackInfo<v8::Value>& args) {
 
   // Decode the function type and construct a signature.
   i::Zone zone(i_isolate->allocator(), ZONE_NAME);
-  i::wasm::FunctionSig::Builder builder(&zone, parameters_len, results_len);
+  i::wasm::FunctionSig::Builder builder(&zone, results_len, parameters_len);
   for (uint32_t i = 0; i < parameters_len; ++i) {
     i::wasm::ValueType type;
     MaybeLocal<Value> maybe = parameters->Get(context, i);
@@ -1513,13 +1513,12 @@ void WebAssemblyFunctionType(const v8::FunctionCallbackInfo<v8::Value>& args) {
   ScheduledErrorThrower thrower(i_isolate, "WebAssembly.Function.type()");
 
   i::wasm::FunctionSig* sig;
+  i::Zone zone(i_isolate->allocator(), ZONE_NAME);
   i::Handle<i::Object> arg0 = Utils::OpenHandle(*args[0]);
   if (i::WasmExportedFunction::IsWasmExportedFunction(*arg0)) {
     sig = i::Handle<i::WasmExportedFunction>::cast(arg0)->sig();
   } else if (i::WasmJSFunction::IsWasmJSFunction(*arg0)) {
-    // TODO(7742): Implement deserialization of signature.
-    sig = nullptr;
-    UNIMPLEMENTED();
+    sig = i::Handle<i::WasmJSFunction>::cast(arg0)->GetSignature(&zone);
   } else {
     thrower.TypeError("Argument 0 must be a WebAssembly.Function");
     return;

src/wasm/wasm-objects-inl.h

@@ -317,6 +317,12 @@ CAST_ACCESSOR(WasmJSFunction)
 // WasmJSFunctionData
 OBJECT_CONSTRUCTORS_IMPL(WasmJSFunctionData, Struct)
 CAST_ACCESSOR(WasmJSFunctionData)
+SMI_ACCESSORS(WasmJSFunctionData, serialized_return_count,
+              kSerializedReturnCountOffset)
+SMI_ACCESSORS(WasmJSFunctionData, serialized_parameter_count,
+              kSerializedParameterCountOffset)
+ACCESSORS(WasmJSFunctionData, serialized_signature, PodArray<wasm::ValueType>,
+          kSerializedSignatureOffset)
 ACCESSORS(WasmJSFunctionData, wrapper_code, Code, kWrapperCodeOffset)
 
 // WasmCapiFunction

src/wasm/wasm-objects.cc

@@ -2143,9 +2143,19 @@ bool WasmJSFunction::IsWasmJSFunction(Object object) {
 Handle<WasmJSFunction> WasmJSFunction::New(Isolate* isolate,
                                            wasm::FunctionSig* sig,
                                            Handle<JSReceiver> callable) {
+  DCHECK_LE(sig->all().size(), kMaxInt);
+  int sig_size = static_cast<int>(sig->all().size());
+  int return_count = static_cast<int>(sig->return_count());
+  int parameter_count = static_cast<int>(sig->parameter_count());
+  Handle<PodArray<wasm::ValueType>> serialized_sig =
+      PodArray<wasm::ValueType>::New(isolate, sig_size, AllocationType::kOld);
+  serialized_sig->copy_in(0, sig->all().begin(), sig_size);
   Handle<WasmJSFunctionData> function_data =
       Handle<WasmJSFunctionData>::cast(isolate->factory()->NewStruct(
           WASM_JS_FUNCTION_DATA_TYPE, AllocationType::kOld));
+  function_data->set_serialized_return_count(return_count);
+  function_data->set_serialized_parameter_count(parameter_count);
+  function_data->set_serialized_signature(*serialized_sig);
   // TODO(7742): Make this callable by using a proper wrapper code.
   function_data->set_wrapper_code(
       isolate->builtins()->builtin(Builtins::kIllegal));
@@ -2160,6 +2170,16 @@ Handle<WasmJSFunction> WasmJSFunction::New(Isolate* isolate,
   return Handle<WasmJSFunction>::cast(js_function);
 }
 
+wasm::FunctionSig* WasmJSFunction::GetSignature(Zone* zone) {
+  WasmJSFunctionData function_data = shared().wasm_js_function_data();
+  int sig_size = function_data.serialized_signature().length();
+  wasm::ValueType* types = zone->NewArray<wasm::ValueType>(sig_size);
+  function_data.serialized_signature().copy_out(0, types, sig_size);
+  int return_count = function_data.serialized_return_count();
+  int parameter_count = function_data.serialized_parameter_count();
+  return new (zone) wasm::FunctionSig(return_count, parameter_count, types);
+}
+
 Address WasmCapiFunction::GetHostCallTarget() const {
   return shared().wasm_capi_function_data().call_target();
 }

src/wasm/wasm-objects.h

@@ -681,6 +681,10 @@ class WasmJSFunction : public JSFunction {
   static Handle<WasmJSFunction> New(Isolate* isolate, wasm::FunctionSig* sig,
                                     Handle<JSReceiver> callable);
 
+  // Deserializes the signature of this function using the provided zone. Note
+  // that lifetime of the signature is hence directly coupled to the zone.
+  wasm::FunctionSig* GetSignature(Zone* zone);
+
   DECL_CAST(WasmJSFunction)
   OBJECT_CONSTRUCTORS(WasmJSFunction, JSFunction);
 };
@@ -754,6 +758,9 @@ class WasmExportedFunctionData : public Struct {
 // {SharedFunctionInfo::HasWasmJSFunctionData} predicate.
 class WasmJSFunctionData : public Struct {
  public:
+  DECL_INT_ACCESSORS(serialized_return_count)
+  DECL_INT_ACCESSORS(serialized_parameter_count)
+  DECL_ACCESSORS(serialized_signature, PodArray<wasm::ValueType>)
   DECL_ACCESSORS(wrapper_code, Code)
 
   DECL_CAST(WasmJSFunctionData)

test/mjsunit/wasm/type-reflection.js

@@ -239,6 +239,21 @@ load('test/mjsunit/wasm/wasm-module-builder.js');
   assertDoesNotThrow(() => fun());
 })();
 
+(function TestFunctionTypeOfConstructedFunction() {
+  let testcases = [
+    {parameters:[], results:[]},
+    {parameters:["i32"], results:[]},
+    {parameters:["i64"], results:["i32"]},
+    {parameters:["f64", "f64", "i32"], results:[]},
+    {parameters:["f32"], results:["f32"]},
+  ];
+  testcases.forEach(function(expected) {
+    let fun = new WebAssembly.Function(expected, _ => 0);
+    let type = WebAssembly.Function.type(fun);
+    assertEquals(expected, type)
+  });
+})();
+
 (function TestFunctionTypeOfExportedFunction() {
   let testcases = [
     [kSig_v_v, {parameters:[], results:[]}],