src/wasm/wasm-js.cc

// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/api.h"
#include "src/api-natives.h"
#include "src/assert-scope.h"
#include "src/ast/ast.h"
#include "src/ast/scopes.h"
#include "src/factory.h"
#include "src/handles.h"
#include "src/isolate.h"
#include "src/objects.h"
#include "src/parsing/parser.h"
#include "src/typing-asm.h"

#include "src/wasm/asm-wasm-builder.h"
#include "src/wasm/encoder.h"
#include "src/wasm/module-decoder.h"
#include "src/wasm/wasm-js.h"
#include "src/wasm/wasm-module.h"
#include "src/wasm/wasm-result.h"

typedef uint8_t byte;

using v8::internal::wasm::ErrorThrower;

namespace v8 {

namespace {
struct RawBuffer {
  const byte* start;
  const byte* end;
  size_t size() { return static_cast<size_t>(end - start); }
};

RawBuffer GetRawBufferArgument(
    ErrorThrower& thrower, const v8::FunctionCallbackInfo<v8::Value>& args) {
  if (args.Length() < 1) {
    thrower.Error("Argument 0 must be an array buffer");
    return {nullptr, nullptr};
  }

  const byte* start = nullptr;
  const byte* end = nullptr;

  if (args[0]->IsArrayBuffer()) {
    // A raw array buffer was passed.
    Local<ArrayBuffer> buffer = Local<ArrayBuffer>::Cast(args[0]);
    ArrayBuffer::Contents contents = buffer->GetContents();

    start = reinterpret_cast<const byte*>(contents.Data());
    end = start + contents.ByteLength();

    if (start == nullptr || end == start) {
      thrower.Error("ArrayBuffer argument is empty");
    }
  } else if (args[0]->IsTypedArray()) {
    // A TypedArray was passed.
    Local<TypedArray> array = Local<TypedArray>::Cast(args[0]);
    Local<ArrayBuffer> buffer = array->Buffer();

    ArrayBuffer::Contents contents = buffer->GetContents();

    start =
        reinterpret_cast<const byte*>(contents.Data()) + array->ByteOffset();
    end = start + array->ByteLength();

    if (start == nullptr || end == start) {
      thrower.Error("ArrayBuffer argument is empty");
    }
  } else {
    thrower.Error("Argument 0 must be an ArrayBuffer or Uint8Array");
  }

  return {start, end};
}

void VerifyModule(const v8::FunctionCallbackInfo<v8::Value>& args) {
  HandleScope scope(args.GetIsolate());
  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
  ErrorThrower thrower(isolate, "WASM.verifyModule()");

  RawBuffer buffer = GetRawBufferArgument(thrower, args);
  if (thrower.error()) return;

  i::Zone zone(isolate->allocator());
  internal::wasm::ModuleResult result =
      internal::wasm::DecodeWasmModule(isolate, &zone, buffer.start, buffer.end,
                                       true, internal::wasm::kWasmOrigin);

  if (result.failed()) {
    thrower.Failed("", result);
  }

  if (result.val) delete result.val;
}

void VerifyFunction(const v8::FunctionCallbackInfo<v8::Value>& args) {
  HandleScope scope(args.GetIsolate());
  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
  ErrorThrower thrower(isolate, "WASM.verifyFunction()");

  RawBuffer buffer = GetRawBufferArgument(thrower, args);
  if (thrower.error()) return;

  internal::wasm::FunctionResult result;
  {
    // Verification of a single function shouldn't allocate.
    i::DisallowHeapAllocation no_allocation;
    i::Zone zone(isolate->allocator());
    result = internal::wasm::DecodeWasmFunction(isolate, &zone, nullptr,
                                                buffer.start, buffer.end);
  }

  if (result.failed()) {
    thrower.Failed("", result);
  }

  if (result.val) delete result.val;
}

v8::internal::wasm::WasmModuleIndex* TranslateAsmModule(
    i::ParseInfo* info, i::Handle<i::Object> foreign, ErrorThrower* thrower) {
  info->set_global();
  info->set_lazy(false);
  info->set_allow_lazy_parsing(false);
  info->set_toplevel(true);

  if (!i::Compiler::ParseAndAnalyze(info)) {
    return nullptr;
  }

  if (info->scope()->declarations()->length() == 0) {
    thrower->Error("Asm.js validation failed: no declarations in scope");
    return nullptr;
  }

  info->set_literal(
      info->scope()->declarations()->at(0)->AsFunctionDeclaration()->fun());

  v8::internal::AsmTyper typer(info->isolate(), info->zone(), *(info->script()),
                               info->literal());
  if (i::FLAG_enable_simd_asmjs) {
    typer.set_allow_simd(true);
  }
  if (!typer.Validate()) {
    thrower->Error("Asm.js validation failed: %s", typer.error_message());
    return nullptr;
  }

  auto module =
      v8::internal::wasm::AsmWasmBuilder(info->isolate(), info->zone(),
                                         info->literal(), foreign, &typer)
          .Run();

  return module;
}

void InstantiateModuleCommon(const v8::FunctionCallbackInfo<v8::Value>& args,
                             const byte* start, const byte* end,
                             ErrorThrower* thrower,
                             internal::wasm::ModuleOrigin origin) {
  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());

  i::Handle<i::JSArrayBuffer> memory = i::Handle<i::JSArrayBuffer>::null();
  if (args.Length() > 2 && args[2]->IsArrayBuffer()) {
    Local<Object> obj = Local<Object>::Cast(args[2]);
    i::Handle<i::Object> mem_obj = v8::Utils::OpenHandle(*obj);
    memory = i::Handle<i::JSArrayBuffer>(i::JSArrayBuffer::cast(*mem_obj));
  }

  // Decode but avoid a redundant pass over function bodies for verification.
  // Verification will happen during compilation.
  i::Zone zone(isolate->allocator());
  internal::wasm::ModuleResult result = internal::wasm::DecodeWasmModule(
      isolate, &zone, start, end, false, origin);

  if (result.failed() && origin == internal::wasm::kAsmJsOrigin) {
    thrower->Error("Asm.js converted module failed to decode");
  } else if (result.failed()) {
    thrower->Failed("", result);
  } else {
    // Success. Instantiate the module and return the object.
    i::Handle<i::JSReceiver> ffi = i::Handle<i::JSObject>::null();
    if (args.Length() > 1 && args[1]->IsObject()) {
      Local<Object> obj = Local<Object>::Cast(args[1]);
      ffi = i::Handle<i::JSReceiver>::cast(v8::Utils::OpenHandle(*obj));
    }

    i::MaybeHandle<i::JSObject> object =
        result.val->Instantiate(isolate, ffi, memory);

    if (!object.is_null()) {
      args.GetReturnValue().Set(v8::Utils::ToLocal(object.ToHandleChecked()));
    }
  }

  if (result.val) delete result.val;
}

void InstantiateModuleFromAsm(const v8::FunctionCallbackInfo<v8::Value>& args) {
  HandleScope scope(args.GetIsolate());
  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
  ErrorThrower thrower(isolate, "WASM.instantiateModuleFromAsm()");

  if (!args[0]->IsString()) {
    thrower.Error("Asm module text should be a string");
    return;
  }

  i::Factory* factory = isolate->factory();
  i::Zone zone(isolate->allocator());
  Local<String> source = Local<String>::Cast(args[0]);
  i::Handle<i::Script> script = factory->NewScript(Utils::OpenHandle(*source));
  i::ParseInfo info(&zone, script);

  i::Handle<i::Object> foreign;
  if (args.Length() > 1 && args[1]->IsObject()) {
    Local<Object> local_foreign = Local<Object>::Cast(args[1]);
    foreign = v8::Utils::OpenHandle(*local_foreign);
  }

  auto module = TranslateAsmModule(&info, foreign, &thrower);
  if (module == nullptr) {
    return;
  }

  InstantiateModuleCommon(args, module->Begin(), module->End(), &thrower,
                          internal::wasm::kAsmJsOrigin);
}

void InstantiateModule(const v8::FunctionCallbackInfo<v8::Value>& args) {
  HandleScope scope(args.GetIsolate());
  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
  ErrorThrower thrower(isolate, "WASM.instantiateModule()");

  RawBuffer buffer = GetRawBufferArgument(thrower, args);
  if (buffer.start == nullptr) return;

  InstantiateModuleCommon(args, buffer.start, buffer.end, &thrower,
                          internal::wasm::kWasmOrigin);
}
}  // namespace

// TODO(titzer): we use the API to create the function template because the
// internal guts are too ugly to replicate here.
static i::Handle<i::FunctionTemplateInfo> NewTemplate(i::Isolate* i_isolate,
                                                      FunctionCallback func) {
  Isolate* isolate = reinterpret_cast<Isolate*>(i_isolate);
  Local<FunctionTemplate> local = FunctionTemplate::New(isolate, func);
  return v8::Utils::OpenHandle(*local);
}

namespace internal {
static Handle<String> v8_str(Isolate* isolate, const char* str) {
  return isolate->factory()->NewStringFromAsciiChecked(str);
}

static void InstallFunc(Isolate* isolate, Handle<JSObject> object,
                        const char* str, FunctionCallback func) {
  Handle<String> name = v8_str(isolate, str);
  Handle<FunctionTemplateInfo> temp = NewTemplate(isolate, func);
  Handle<JSFunction> function =
      ApiNatives::InstantiateFunction(temp).ToHandleChecked();
  PropertyAttributes attributes =
      static_cast<PropertyAttributes>(DONT_DELETE | READ_ONLY);
  JSObject::AddProperty(object, name, function, attributes);
}

void WasmJs::Install(Isolate* isolate, Handle<JSGlobalObject> global) {
  // Setup wasm function map.
  Handle<Context> context(global->native_context(), isolate);
  InstallWasmFunctionMap(isolate, context);

  // Bind the WASM object.
  Factory* factory = isolate->factory();
  Handle<String> name = v8_str(isolate, "Wasm");
  Handle<JSFunction> cons = factory->NewFunction(name);
  JSFunction::SetInstancePrototype(
      cons, Handle<Object>(context->initial_object_prototype(), isolate));
  cons->shared()->set_instance_class_name(*name);
  Handle<JSObject> wasm_object = factory->NewJSObject(cons, TENURED);
  PropertyAttributes attributes = static_cast<PropertyAttributes>(DONT_ENUM);
  JSObject::AddProperty(global, name, wasm_object, attributes);

  // Install functions on the WASM object.
  InstallFunc(isolate, wasm_object, "verifyModule", VerifyModule);
  InstallFunc(isolate, wasm_object, "verifyFunction", VerifyFunction);
  InstallFunc(isolate, wasm_object, "instantiateModule", InstantiateModule);
  InstallFunc(isolate, wasm_object, "instantiateModuleFromAsm",
              InstantiateModuleFromAsm);

  {
    // Add the Wasm.experimentalVersion property.
    Handle<String> name = v8_str(isolate, "experimentalVersion");
    PropertyAttributes attributes =
        static_cast<PropertyAttributes>(DONT_DELETE | READ_ONLY);
    Handle<Smi> value = Handle<Smi>(Smi::FromInt(wasm::kWasmVersion), isolate);
    JSObject::AddProperty(wasm_object, name, value, attributes);
  }
}

void WasmJs::InstallWasmFunctionMap(Isolate* isolate, Handle<Context> context) {
  if (!context->get(Context::WASM_FUNCTION_MAP_INDEX)->IsMap()) {
    // TODO(titzer): Move this to bootstrapper.cc??
    // TODO(titzer): Also make one for strict mode functions?
    Handle<Map> prev_map = Handle<Map>(context->sloppy_function_map(), isolate);

    InstanceType instance_type = prev_map->instance_type();
    int internal_fields = JSObject::GetInternalFieldCount(*prev_map);
    CHECK_EQ(0, internal_fields);
    int pre_allocated =
        prev_map->GetInObjectProperties() - prev_map->unused_property_fields();
    int instance_size;
    int in_object_properties;
    JSFunction::CalculateInstanceSizeHelper(instance_type, internal_fields + 1,
                                            0, &instance_size,
                                            &in_object_properties);

    int unused_property_fields = in_object_properties - pre_allocated;
    Handle<Map> map = Map::CopyInitialMap(
        prev_map, instance_size, in_object_properties, unused_property_fields);

    context->set_wasm_function_map(*map);
  }
}

}  // namespace internal
}  // namespace v8