runtime/vm/native_arguments.h - sdk - Git at Google

 // 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 RUNTIME_VM_NATIVE_ARGUMENTS_H_
 #define RUNTIME_VM_NATIVE_ARGUMENTS_H_

 #include "platform/assert.h"
 #include "platform/memory_sanitizer.h"
 #include "vm/globals.h"
 #include "vm/simulator.h"
 #include "vm/stub_code.h"

 namespace dart {

 // Forward declarations.
 class BootstrapNatives;
 class Object;
 class Simulator;
 class Thread;

 #if defined(TESTING) || defined(DEBUG)

 #if defined(USING_SIMULATOR)
 #define CHECK_STACK_ALIGNMENT                                                  \
   {                                                                            \
     uword current_sp = Simulator::Current()->get_register(SPREG);              \
     ASSERT(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment()));      \
   }
 #elif defined(DART_HOST_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::GetCStackPointer().EntryPoint());                            \
     uword current_sp = func();                                                 \
     ASSERT(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment()));      \
   }
 #endif

 #define DEOPTIMIZE_ALOT                                                        \
   if (FLAG_deoptimize_alot) {                                                  \
     DeoptimizeFunctionsOnStack();                                              \
   }

 #else

 #define CHECK_STACK_ALIGNMENT                                                  \
   {}
 #define DEOPTIMIZE_ALOT                                                        \
   {}

 #endif

 // 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.NativeArgAt(0));
 //   const Smi& arg1 = Smi::CheckedHandle(arguments.NativeArgAt(1));
 // If the function is generic, type arguments are accessed as follows:
 //   const TypeArguments& type_args =
 //       TypeArguments::Handle(arguments.NativeTypeArgs());
 // 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:
   Thread* thread() const { return thread_; }

   // Includes type arguments vector.
   int ArgCount() const { return ArgcBits::decode(argc_tag_); }

   ObjectPtr ArgAt(int index) const {
     ASSERT((index >= 0) && (index < ArgCount()));
     ObjectPtr* arg_ptr = &(argv_[-index]);
     // Tell MemorySanitizer the ObjectPtr was initialized (by generated code).
     MSAN_UNPOISON(arg_ptr, kWordSize);
     return *arg_ptr;
   }

   void SetArgAt(int index, const Object& value) const {
     ASSERT(thread_->execution_state() == Thread::kThreadInVM);
     ASSERT((index >= 0) && (index < ArgCount()));
     argv_[-index] = value.ptr();
   }

   // Does not include hidden type arguments vector.
   int NativeArgCount() const {
     int function_bits = FunctionBits::decode(argc_tag_);
     return ArgCount() - NumHiddenArgs(function_bits);
   }

   ObjectPtr NativeArg0() const {
     int function_bits = FunctionBits::decode(argc_tag_);
     if ((function_bits & (kClosureFunctionBit | kInstanceFunctionBit)) ==
         (kClosureFunctionBit | kInstanceFunctionBit)) {
       // Retrieve the receiver from the context.
       const int closure_index =
           (function_bits & kGenericFunctionBit) != 0 ? 1 : 0;
       const Object& closure = Object::Handle(ArgAt(closure_index));
       const Context& context =
           Context::Handle(Closure::Cast(closure).context());
       return context.At(0);
     }
     return ArgAt(NumHiddenArgs(function_bits));
   }

   ObjectPtr NativeArgAt(int index) const {
     ASSERT((index >= 0) && (index < NativeArgCount()));
     if (index == 0) {
       return NativeArg0();
     }
     int function_bits = FunctionBits::decode(argc_tag_);
     const int actual_index = index + NumHiddenArgs(function_bits);
     return ArgAt(actual_index);
   }

   TypeArgumentsPtr NativeTypeArgs() const {
     ASSERT(ToGenericFunction());
     return TypeArguments::RawCast(ArgAt(0));
   }

   int NativeTypeArgCount() const {
     if (ToGenericFunction()) {
       TypeArguments& type_args = TypeArguments::Handle(NativeTypeArgs());
       if (type_args.IsNull()) {
         // null vector represents infinite list of dynamics
         return INT_MAX;
       }
       return type_args.Length();
     }
     return 0;
   }

   AbstractTypePtr NativeTypeArgAt(int index) const {
     ASSERT((index >= 0) && (index < NativeTypeArgCount()));
     TypeArguments& type_args = TypeArguments::Handle(NativeTypeArgs());
     if (type_args.IsNull()) {
       // null vector represents infinite list of dynamics
       return Type::dynamic_type().ptr();
     }
     return type_args.TypeAt(index);
   }

   void SetReturn(const Object& value) const {
     ASSERT(thread_->execution_state() == Thread::kThreadInVM);
     *retval_ = value.ptr();
   }

   ObjectPtr ReturnValue() const {
     // Tell MemorySanitizer the retval_ was initialized (by generated code).
     MSAN_UNPOISON(retval_, kWordSize);
     return *retval_;
   }

   static intptr_t thread_offset() {
     return OFFSET_OF(NativeArguments, thread_);
   }
   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 intptr_t ParameterCountForResolution(const Function& function) {
     ASSERT(function.is_native());
     ASSERT(!function.IsGenerativeConstructor());  // Not supported.
     intptr_t 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 hiding the closure object at index 0.
       count--;
     }
     return count;
   }

   static int ComputeArgcTag(const Function& function) {
     ASSERT(function.is_native());
     ASSERT(!function.IsGenerativeConstructor());  // Not supported.
     int argc = function.NumParameters();
     int function_bits = 0;
     if (!function.is_static()) {
       function_bits |= kInstanceFunctionBit;
     }
     if (function.IsClosureFunction()) {
       function_bits |= kClosureFunctionBit;
     }
     if (function.IsGeneric()) {
       function_bits |= kGenericFunctionBit;
       argc++;
     }
     int tag = ArgcBits::encode(argc);
     tag = FunctionBits::update(function_bits, tag);
     return tag;
   }

  private:
   enum {
     kInstanceFunctionBit = 1,
     kClosureFunctionBit = 2,
     kGenericFunctionBit = 4,
   };
   enum ArgcTagBits {
     kArgcBit = 0,
     kArgcSize = 24,
     kFunctionBit = kArgcBit + kArgcSize,
     kFunctionSize = 3,
   };
   class ArgcBits : public BitField<intptr_t, int32_t, kArgcBit, kArgcSize> {};
   class FunctionBits
       : public BitField<intptr_t, int, kFunctionBit, kFunctionSize> {};
   friend class Api;
   friend class NativeEntry;
   friend class Simulator;

   // Since this function is passed an ObjectPtr 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(ObjectPtr value) const {
     ASSERT(thread_->execution_state() == Thread::kThreadInVM);
     *retval_ = value;
   }

   // Returns true if the arguments are those of an instance function call.
   bool ToInstanceFunction() const {
     return (FunctionBits::decode(argc_tag_) & kInstanceFunctionBit) != 0;
   }

   // Returns true if the arguments are those of a closure function call.
   bool ToClosureFunction() const {
     return (FunctionBits::decode(argc_tag_) & kClosureFunctionBit) != 0;
   }

   // Returns true if the arguments are those of a generic function call.
   bool ToGenericFunction() const {
     return (FunctionBits::decode(argc_tag_) & kGenericFunctionBit) != 0;
   }

   int NumHiddenArgs(int function_bits) const {
     int num_hidden_args = 0;
     // 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 ((function_bits & kClosureFunctionBit) == kClosureFunctionBit) {
       num_hidden_args++;
     }
     if ((function_bits & kGenericFunctionBit) == kGenericFunctionBit) {
       num_hidden_args++;
     }
     return num_hidden_args;
   }

   Thread* thread_;      // Current thread pointer.
   intptr_t argc_tag_;   // Encodes argument count and invoked native call type.
   ObjectPtr* argv_;     // Pointer to an array of arguments to runtime call.
   ObjectPtr* retval_;   // Pointer to the return value area.
 };

 }  // namespace dart

 #endif  // RUNTIME_VM_NATIVE_ARGUMENTS_H_
	// 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 RUNTIME_VM_NATIVE_ARGUMENTS_H_
	#define RUNTIME_VM_NATIVE_ARGUMENTS_H_

	#include "platform/assert.h"
	#include "platform/memory_sanitizer.h"
	#include "vm/globals.h"
	#include "vm/simulator.h"
	#include "vm/stub_code.h"

	namespace dart {

	// Forward declarations.
	class BootstrapNatives;
	class Object;
	class Simulator;
	class Thread;

	#if defined(TESTING) \|\| defined(DEBUG)

	#if defined(USING_SIMULATOR)
	#define CHECK_STACK_ALIGNMENT \
	{ \
	uword current_sp = Simulator::Current()->get_register(SPREG); \
	ASSERT(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment())); \
	}
	#elif defined(DART_HOST_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::GetCStackPointer().EntryPoint()); \
	uword current_sp = func(); \
	ASSERT(Utils::IsAligned(current_sp, OS::ActivationFrameAlignment())); \
	}
	#endif

	#define DEOPTIMIZE_ALOT \
	if (FLAG_deoptimize_alot) { \
	DeoptimizeFunctionsOnStack(); \
	}

	#else

	#define CHECK_STACK_ALIGNMENT \
	{}
	#define DEOPTIMIZE_ALOT \
	{}

	#endif

	// 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.NativeArgAt(0));
	// const Smi& arg1 = Smi::CheckedHandle(arguments.NativeArgAt(1));
	// If the function is generic, type arguments are accessed as follows:
	// const TypeArguments& type_args =
	// TypeArguments::Handle(arguments.NativeTypeArgs());
	// 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:
	Thread* thread() const { return thread_; }

	// Includes type arguments vector.
	int ArgCount() const { return ArgcBits::decode(argc_tag_); }

	ObjectPtr ArgAt(int index) const {
	ASSERT((index >= 0) && (index < ArgCount()));
	ObjectPtr* arg_ptr = &(argv_[-index]);
	// Tell MemorySanitizer the ObjectPtr was initialized (by generated code).
	MSAN_UNPOISON(arg_ptr, kWordSize);
	return *arg_ptr;
	}

	void SetArgAt(int index, const Object& value) const {
	ASSERT(thread_->execution_state() == Thread::kThreadInVM);
	ASSERT((index >= 0) && (index < ArgCount()));
	argv_[-index] = value.ptr();
	}

	// Does not include hidden type arguments vector.
	int NativeArgCount() const {
	int function_bits = FunctionBits::decode(argc_tag_);
	return ArgCount() - NumHiddenArgs(function_bits);
	}

	ObjectPtr NativeArg0() const {
	int function_bits = FunctionBits::decode(argc_tag_);
	if ((function_bits & (kClosureFunctionBit \| kInstanceFunctionBit)) ==
	(kClosureFunctionBit \| kInstanceFunctionBit)) {
	// Retrieve the receiver from the context.
	const int closure_index =
	(function_bits & kGenericFunctionBit) != 0 ? 1 : 0;
	const Object& closure = Object::Handle(ArgAt(closure_index));
	const Context& context =
	Context::Handle(Closure::Cast(closure).context());
	return context.At(0);
	}
	return ArgAt(NumHiddenArgs(function_bits));
	}

	ObjectPtr NativeArgAt(int index) const {
	ASSERT((index >= 0) && (index < NativeArgCount()));
	if (index == 0) {
	return NativeArg0();
	}
	int function_bits = FunctionBits::decode(argc_tag_);
	const int actual_index = index + NumHiddenArgs(function_bits);
	return ArgAt(actual_index);
	}

	TypeArgumentsPtr NativeTypeArgs() const {
	ASSERT(ToGenericFunction());
	return TypeArguments::RawCast(ArgAt(0));
	}

	int NativeTypeArgCount() const {
	if (ToGenericFunction()) {
	TypeArguments& type_args = TypeArguments::Handle(NativeTypeArgs());
	if (type_args.IsNull()) {
	// null vector represents infinite list of dynamics
	return INT_MAX;
	}
	return type_args.Length();
	}
	return 0;
	}

	AbstractTypePtr NativeTypeArgAt(int index) const {
	ASSERT((index >= 0) && (index < NativeTypeArgCount()));
	TypeArguments& type_args = TypeArguments::Handle(NativeTypeArgs());
	if (type_args.IsNull()) {
	// null vector represents infinite list of dynamics
	return Type::dynamic_type().ptr();
	}
	return type_args.TypeAt(index);
	}

	void SetReturn(const Object& value) const {
	ASSERT(thread_->execution_state() == Thread::kThreadInVM);
	*retval_ = value.ptr();
	}

	ObjectPtr ReturnValue() const {
	// Tell MemorySanitizer the retval_ was initialized (by generated code).
	MSAN_UNPOISON(retval_, kWordSize);
	return *retval_;
	}

	static intptr_t thread_offset() {
	return OFFSET_OF(NativeArguments, thread_);
	}
	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 intptr_t ParameterCountForResolution(const Function& function) {
	ASSERT(function.is_native());
	ASSERT(!function.IsGenerativeConstructor()); // Not supported.
	intptr_t 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 hiding the closure object at index 0.
	count--;
	}
	return count;
	}

	static int ComputeArgcTag(const Function& function) {
	ASSERT(function.is_native());
	ASSERT(!function.IsGenerativeConstructor()); // Not supported.
	int argc = function.NumParameters();
	int function_bits = 0;
	if (!function.is_static()) {
	function_bits \|= kInstanceFunctionBit;
	}
	if (function.IsClosureFunction()) {
	function_bits \|= kClosureFunctionBit;
	}
	if (function.IsGeneric()) {
	function_bits \|= kGenericFunctionBit;
	argc++;
	}
	int tag = ArgcBits::encode(argc);
	tag = FunctionBits::update(function_bits, tag);
	return tag;
	}

	private:
	enum {
	kInstanceFunctionBit = 1,
	kClosureFunctionBit = 2,
	kGenericFunctionBit = 4,
	};
	enum ArgcTagBits {
	kArgcBit = 0,
	kArgcSize = 24,
	kFunctionBit = kArgcBit + kArgcSize,
	kFunctionSize = 3,
	};
	class ArgcBits : public BitField<intptr_t, int32_t, kArgcBit, kArgcSize> {};
	class FunctionBits
	: public BitField<intptr_t, int, kFunctionBit, kFunctionSize> {};
	friend class Api;
	friend class NativeEntry;
	friend class Simulator;

	// Since this function is passed an ObjectPtr 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(ObjectPtr value) const {
	ASSERT(thread_->execution_state() == Thread::kThreadInVM);
	*retval_ = value;
	}

	// Returns true if the arguments are those of an instance function call.
	bool ToInstanceFunction() const {
	return (FunctionBits::decode(argc_tag_) & kInstanceFunctionBit) != 0;
	}

	// Returns true if the arguments are those of a closure function call.
	bool ToClosureFunction() const {
	return (FunctionBits::decode(argc_tag_) & kClosureFunctionBit) != 0;
	}

	// Returns true if the arguments are those of a generic function call.
	bool ToGenericFunction() const {
	return (FunctionBits::decode(argc_tag_) & kGenericFunctionBit) != 0;
	}

	int NumHiddenArgs(int function_bits) const {
	int num_hidden_args = 0;
	// 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 ((function_bits & kClosureFunctionBit) == kClosureFunctionBit) {
	num_hidden_args++;
	}
	if ((function_bits & kGenericFunctionBit) == kGenericFunctionBit) {
	num_hidden_args++;
	}
	return num_hidden_args;
	}

	Thread* thread_; // Current thread pointer.
	intptr_t argc_tag_; // Encodes argument count and invoked native call type.
	ObjectPtr* argv_; // Pointer to an array of arguments to runtime call.
	ObjectPtr* retval_; // Pointer to the return value area.
	};

	} // namespace dart

	#endif // RUNTIME_VM_NATIVE_ARGUMENTS_H_