FFI Compiler based on code stub assembler

src/ffi/ffi-compiler.cc

+// Copyright 2017 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/ffi/ffi-compiler.h"
+#include "src/api.h"
+#include "src/code-factory.h"
+
+namespace v8 {
+namespace internal {
+
+void InstallFFIMap(Isolate* isolate) {
+  Handle<Context> context(isolate->context());
+  DCHECK(!context->get(Context::NATIVE_FUNCTION_MAP_INDEX)->IsMap());
+  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, 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_native_function_map(*map);
+}
+
+namespace ffi {
+
+class FFIAssembler : public CodeStubAssembler {
+ public:
+  explicit FFIAssembler(CodeAssemblerState* state) : CodeStubAssembler(state) {}
+
+  Node* ToJS(Node* node, Node* context, MachineType type) {
+    UNREACHABLE();
+    // TODO(mattloring): Needs to be implemented.
+    return nullptr;
+  }
+
+  Node* FromJS(Node* node, Node* context, MachineType type) {
+    UNREACHABLE();
+    // TODO(mattloring): Needs to be implemented.
+    return nullptr;
+  }
+
+  void GenerateJSToNativeWrapper(NativeFunction* func) {
+    int params = static_cast<int>(func->sig->parameter_count());
+    int returns = static_cast<int>(func->sig->return_count());
+    ApiFunction api_func(func->start);
+    ExternalReference ref(&api_func, ExternalReference::DIRECT_API_CALL,
+                          isolate());
+
+    Node* context_param = GetJSContextParameter();
+
+    Node** inputs = zone()->NewArray<Node*>(params + 1);
+    int input_count = 0;
+    inputs[input_count++] = ExternalConstant(ref);
+    for (int i = 0; i < params; i++) {
+      inputs[input_count++] =
+          FromJS(Parameter(i), context_param, func->sig->GetParam(i));
+    }
+
+    Node* call = CallCFunctionN(func->sig, input_count, inputs);
+    Node* return_val = UndefinedConstant();
+    if (returns == 1) {
+      return_val = ToJS(call, context_param, func->sig->GetReturn());
+    }
+    Return(return_val);
+  }
+};
+
+Handle<JSFunction> CompileJSToNativeWrapper(Isolate* isolate,
+                                            Handle<String> name,
+                                            NativeFunction func) {
+  int params = static_cast<int>(func.sig->parameter_count());
+  Zone zone(isolate->allocator(), ZONE_NAME);
+  CodeAssemblerState state(isolate, &zone, params,
+                           Code::ComputeFlags(Code::FUNCTION), "js-to-native");
+  FFIAssembler assembler(&state);
+  assembler.GenerateJSToNativeWrapper(&func);
+  Handle<Code> code = assembler.GenerateCode(&state);
+
+  Handle<SharedFunctionInfo> shared =
+      isolate->factory()->NewSharedFunctionInfo(name, code, false);
+  shared->set_length(params);
+  shared->set_internal_formal_parameter_count(params);
+  Handle<JSFunction> function = isolate->factory()->NewFunction(
+      isolate->native_function_map(), name, code);
+  function->set_shared(*shared);
+  return function;
+}
+
+}  // namespace ffi
+}  // namespace internal
+}  // namespace v8