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// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#ifndef VM_NATIVE_ARGUMENTS_H_
#define VM_NATIVE_ARGUMENTS_H_
#include "platform/assert.h"
#include "vm/globals.h"
#include "vm/simulator.h"
#include "vm/stub_code.h"
namespace dart {
// Forward declarations.
class BootstrapNatives;
class Isolate;
class Object;
class RawObject;
class Simulator;
#if defined(TESTING) || defined(DEBUG)
#if defined(USING_SIMULATOR)
#define CHECK_STACK_ALIGNMENT { \
uword current_sp = Simulator::Current()->get_register(SPREG); \
ASSERT((OS::ActivationFrameAlignment() == 0) || \
(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment()))); \
}
#elif defined(TARGET_OS_WINDOWS)
// The compiler may dynamically align the stack on Windows, so do not check.
#define CHECK_STACK_ALIGNMENT { }
#else
#define CHECK_STACK_ALIGNMENT { \
uword (*func)() = \
reinterpret_cast<uword (*)()>(StubCode::GetStackPointerEntryPoint()); \
uword current_sp = func(); \
ASSERT((OS::ActivationFrameAlignment() == 0) || \
(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment()))); \
}
#endif
#else
#define CHECK_STACK_ALIGNMENT { }
#endif
void SetReturnValueHelper(Dart_NativeArguments, Dart_Handle);
// Class NativeArguments is used to access arguments passed in from
// generated dart code to a runtime function or a dart library native
// function. It is also used to set the return value if any at the slot
// reserved for return values.
// All runtime function/dart library native functions have the
// following signature:
// void function_name(NativeArguments arguments);
// Inside the function, arguments are accessed as follows:
// const Instance& arg0 = Instance::CheckedHandle(arguments.ArgAt(0));
// const Smi& arg1 = Smi::CheckedHandle(arguments.ArgAt(1));
// The return value is set as follows:
// arguments.SetReturn(result);
// NOTE: Since we pass 'this' as a pass-by-value argument in the stubs we don't
// have DISALLOW_COPY_AND_ASSIGN in the class definition and do not make it a
// subclass of ValueObject.
class NativeArguments {
public:
Isolate* isolate() const { return isolate_; }
int ArgCount() const { return ArgcBits::decode(argc_tag_); }
// Returns true if the arguments are those of an instance function call.
bool ToInstanceFunction() const {
return InstanceFunctionBit::decode(argc_tag_);
}
// Returns true if the arguments are those of a closure function call.
bool ToClosureFunction() const {
return ClosureFunctionBit::decode(argc_tag_);
}
RawObject* ArgAt(int index) const {
ASSERT((index >= 0) && (index < ArgCount()));
return (*argv_)[-index];
}
int NumHiddenArgs() const {
// For static closure functions, the closure at index 0 is hidden.
// In the instance closure function case, the receiver is accessed from
// the context and the closure at index 0 is hidden, so the apparent
// argument count remains unchanged.
if (ToClosureFunction() && !ToInstanceFunction()) {
return 1;
}
return 0;
}
int NativeArgCount() const {
return ArgCount() - NumHiddenArgs();
}
RawObject* NativeArgAt(int index) const {
ASSERT((index >= 0) && (index < NativeArgCount()));
if ((index == 0) && ToClosureFunction() && ToInstanceFunction()) {
// Retrieve the receiver from the context.
const Context& context = Context::Handle(isolate_->top_context());
return context.At(0);
} else {
const int actual_index = index + NumHiddenArgs();
return ArgAt(actual_index);
}
}
void SetReturn(const Object& value) const;
static intptr_t isolate_offset() {
return OFFSET_OF(NativeArguments, isolate_);
}
static intptr_t argc_tag_offset() {
return OFFSET_OF(NativeArguments, argc_tag_);
}
static intptr_t argv_offset() { return OFFSET_OF(NativeArguments, argv_); }
static intptr_t retval_offset() {
return OFFSET_OF(NativeArguments, retval_);
}
static int ParameterCountForResolution(const Function& function) {
ASSERT(function.is_native());
ASSERT(!function.IsConstructor()); // Not supported.
int count = function.NumParameters();
if (function.is_static() && function.IsClosureFunction()) {
// The closure object is hidden and not accessible from native code.
// However, if the function is an instance closure function, the captured
// receiver located in the context is made accessible in native code at
// index 0, thereby hidding the closure object at index 0.
count--;
}
return count;
}
static int ComputeArgcTag(const Function& function) {
ASSERT(function.is_native());
ASSERT(!function.IsConstructor()); // Not supported.
int tag = ArgcBits::encode(function.NumParameters());
tag = InstanceFunctionBit::update(!function.is_static(), tag);
tag = ClosureFunctionBit::update(function.IsClosureFunction(), tag);
return tag;
}
private:
enum ArgcTagBits {
kArgcBit = 0,
kArgcSize = 24,
kInstanceFunctionBit = 24,
kClosureFunctionBit = 25,
};
class ArgcBits : public BitField<int, kArgcBit, kArgcSize> {};
class InstanceFunctionBit : public BitField<bool, kInstanceFunctionBit, 1> {};
class ClosureFunctionBit : public BitField<bool, kClosureFunctionBit, 1> {};
friend class BootstrapNatives;
friend class Simulator;
friend void SetReturnValueHelper(Dart_NativeArguments, Dart_Handle);
// Since this function is passed a RawObject directly, we need to be
// exceedingly careful when we use it. If there are any other side
// effects in the statement that may cause GC, it could lead to
// bugs.
void SetReturnUnsafe(RawObject* value) const;
Isolate* isolate_; // Current isolate pointer.
int argc_tag_; // Encodes argument count and invoked native call type.
RawObject*(*argv_)[]; // Pointer to an array of arguments to runtime call.
RawObject** retval_; // Pointer to the return value area.
};
} // namespace dart
#endif // VM_NATIVE_ARGUMENTS_H_