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 *

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 * published by the Free Software Foundation.

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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#ifndef SHARE_VM_UTILITIES_EXCEPTIONS_HPP

#define SHARE_VM_UTILITIES_EXCEPTIONS_HPP

#include "memory/allocation.hpp"

#include "oops/oopsHierarchy.hpp"

#include "utilities/sizes.hpp"

// This file provides the basic support for exception handling in the VM.

// Note: We do not use C++ exceptions to avoid compiler dependencies and

// unpredictable performance.

//

// Scheme: Exceptions are stored with the thread. There is never more

// than one pending exception per thread. All functions that can throw

// an exception carry a THREAD argument (usually the last argument and

// declared with the TRAPS macro). Throwing an exception means setting

// a pending exception in the thread. Upon return from a function that

// can throw an exception, we must check if an exception is pending.

// The CHECK macros do this in a convenient way. Carrying around the

// thread provides also convenient access to it (e.g. for Handle

// creation, w/o the need for recomputation).

// Forward declarations to be independent of the include structure.

// This allows us to have exceptions.hpp included in top.hpp.

class Thread;

class Handle;

class Symbol;

class JavaCallArguments;

// The ThreadShadow class is a helper class to access the _pending_exception

// field of the Thread class w/o having access to the Thread's interface (for

// include hierachy reasons).

class ThreadShadow: public CHeapObj {

 protected:

  oop  _pending_exception;                       // Thread has gc actions.

  const char* _exception_file;                   // file information for exception (debugging only)

  int         _exception_line;                   // line information for exception (debugging only)

  friend void check_ThreadShadow();              // checks _pending_exception offset

  // The following virtual exists only to force creation of a vtable.

  // We need ThreadShadow to have a vtable, even in product builds,

  // so that its layout will start at an offset of zero relative to Thread.

  // Some C++ compilers are so "clever" that they put the ThreadShadow

  // base class at offset 4 in Thread (after Thread's vtable), if they

  // notice that Thread has a vtable but ThreadShadow does not.

  virtual void unused_initial_virtual() { }

 public:

  oop  pending_exception() const                 { return _pending_exception; }

  bool has_pending_exception() const             { return _pending_exception != NULL; }

  const char* exception_file() const             { return _exception_file; }

  int  exception_line() const                    { return _exception_line; }

  // Code generation support

  static ByteSize pending_exception_offset()     { return byte_offset_of(ThreadShadow, _pending_exception); }

  // use THROW whenever possible!

  void set_pending_exception(oop exception, const char* file, int line);

  // use CLEAR_PENDING_EXCEPTION whenever possible!

  void clear_pending_exception();

  ThreadShadow() : _pending_exception(NULL),

                   _exception_file(NULL), _exception_line(0) {}

};

// Exceptions is a helper class that encapsulates all operations

// that require access to the thread interface and which are

// relatively rare. The Exceptions operations should only be

// used directly if the macros below are insufficient.

class Exceptions {

  static bool special_exception(Thread *thread, const char* file, int line, Handle exception);

  static bool special_exception(Thread* thread, const char* file, int line, Symbol* name, const char* message);

 public:

  // this enum is defined to indicate whether it is safe to

  // ignore the encoding scheme of the original message string.

  typedef enum {

    safe_to_utf8 = 0,

    unsafe_to_utf8 = 1

  } ExceptionMsgToUtf8Mode;

  // Throw exceptions: w/o message, w/ message & with formatted message.

  static void _throw_oop(Thread* thread, const char* file, int line, oop exception);

  static void _throw(Thread* thread, const char* file, int line, Handle exception, const char* msg = NULL);

  static void _throw_msg(Thread* thread, const char* file, int line,

                         Symbol* name, const char* message, Handle loader,

                         Handle protection_domain);

  static void _throw_msg(Thread* thread, const char* file, int line,

                         Symbol* name, const char* message);

  static void _throw_args(Thread* thread, const char* file, int line,

                          Symbol* name, Symbol* signature,

                          JavaCallArguments* args);

  static void _throw_msg_cause(Thread* thread, const char* file,

                         int line, Symbol* h_name, const char* message,

                         Handle h_cause, Handle h_loader, Handle h_protection_domain);

  static void _throw_msg_cause(Thread* thread, const char* file, int line,

                            Symbol* name, const char* message, Handle cause);

  // There is no THROW... macro for this method. Caller should remember

  // to do a return after calling it.

  static void fthrow(Thread* thread, const char* file, int line, Symbol* name,

                     const char* format, ...);

  // Create and initialize a new exception

  static Handle new_exception(Thread* thread, Symbol* name,

                              Symbol* signature, JavaCallArguments* args,

                              Handle cause, Handle loader,

                              Handle protection_domain);

  static Handle new_exception(Thread* thread, Symbol* name,

                              const char* message, Handle cause, Handle loader,

                              Handle protection_domain,

                              ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);

 static Handle new_exception(Thread* thread, Symbol* name,

                             const char* message,

                             ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);

  static void throw_stack_overflow_exception(Thread* thread, const char* file, int line);

  // for AbortVMOnException flag

  NOT_PRODUCT(static void debug_check_abort(Handle exception, const char* message = NULL);)

  NOT_PRODUCT(static void debug_check_abort(const char *value_string, const char* message = NULL);)

};

// The THREAD & TRAPS macros facilitate the declaration of functions that throw exceptions.

// Convention: Use the TRAPS macro as the last argument of such a function; e.g.:

//

// int this_function_may_trap(int x, float y, TRAPS)

#define THREAD __the_thread__

#define TRAPS  Thread* THREAD

// The CHECK... macros should be used to pass along a THREAD reference and to check for pending

// exceptions. In special situations it is necessary to handle pending exceptions explicitly,

// in these cases the PENDING_EXCEPTION helper macros should be used.

//

// Macro naming conventions: Macros that end with _ require a result value to be returned. They

// are for functions with non-void result type. The result value is usually ignored because of

// the exception and is only needed for syntactic correctness. The _0 ending is a shortcut for

// _(0) since this is a frequent case. Example:

//

// int result = this_function_may_trap(x_arg, y_arg, CHECK_0);

//

// CAUTION: make sure that the function call using a CHECK macro is not the only statement of a

// conditional branch w/o enclosing {} braces, since the CHECK macros expand into several state-

// ments!

#define PENDING_EXCEPTION                        (((ThreadShadow*)THREAD)->pending_exception())

#define HAS_PENDING_EXCEPTION                    (((ThreadShadow*)THREAD)->has_pending_exception())

#define CLEAR_PENDING_EXCEPTION                  (((ThreadShadow*)THREAD)->clear_pending_exception())

#define CHECK                                    THREAD); if (HAS_PENDING_EXCEPTION) return       ; (0

#define CHECK_(result)                           THREAD); if (HAS_PENDING_EXCEPTION) return result; (0

#define CHECK_0                                  CHECK_(0)

#define CHECK_NH                                 CHECK_(Handle())

#define CHECK_NULL                               CHECK_(NULL)

#define CHECK_false                              CHECK_(false)

// The THROW... macros should be used to throw an exception. They require a THREAD variable to be

// visible within the scope containing the THROW. Usually this is achieved by declaring the function

// with a TRAPS argument.

#define THREAD_AND_LOCATION                      THREAD, __FILE__, __LINE__

#define THROW_OOP(e)                                \

  { Exceptions::_throw_oop(THREAD_AND_LOCATION, e);                             return;  }

#define THROW_HANDLE(e)                                \

  { Exceptions::_throw(THREAD_AND_LOCATION, e);                             return;  }

#define THROW(name)                                 \

  { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return;  }

#define THROW_MSG(name, message)                    \

  { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return;  }

#define THROW_MSG_LOADER(name, message, loader, protection_domain) \

  { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return;  }

#define THROW_ARG(name, signature, args) \

  { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args);   return; }

#define THROW_OOP_(e, result)                       \

  { Exceptions::_throw_oop(THREAD_AND_LOCATION, e);                           return result; }

#define THROW_HANDLE_(e, result)                       \

  { Exceptions::_throw(THREAD_AND_LOCATION, e);                           return result; }

#define THROW_(name, result)                        \

  { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return result; }

#define THROW_MSG_(name, message, result)           \

  { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return result; }

#define THROW_MSG_LOADER_(name, message, loader, protection_domain, result) \

  { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return result; }

#define THROW_ARG_(name, signature, args, result) \

  { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return result; }

#define THROW_MSG_CAUSE_(name, message, cause, result)   \

  { Exceptions::_throw_msg_cause(THREAD_AND_LOCATION, name, message, cause); return result; }

#define THROW_OOP_0(e)                      THROW_OOP_(e, 0)

#define THROW_HANDLE_0(e)                   THROW_HANDLE_(e, 0)

#define THROW_0(name)                       THROW_(name, 0)

#define THROW_MSG_0(name, message)          THROW_MSG_(name, message, 0)

#define THROW_WRAPPED_0(name, oop_to_wrap)  THROW_WRAPPED_(name, oop_to_wrap, 0)

#define THROW_ARG_0(name, signature, arg)   THROW_ARG_(name, signature, arg, 0)

#define THROW_MSG_CAUSE_0(name, message, cause) THROW_MSG_CAUSE_(name, message, cause, 0)

#define THROW_NULL(name)                    THROW_(name, NULL)

#define THROW_MSG_NULL(name, message)       THROW_MSG_(name, message, NULL)

// The CATCH macro checks that no exception has been thrown by a function; it is used at

// call sites about which is statically known that the callee cannot throw an exception

// even though it is declared with TRAPS.

#define CATCH                              \

  THREAD); if (HAS_PENDING_EXCEPTION) {    \

    oop ex = PENDING_EXCEPTION;            \

    CLEAR_PENDING_EXCEPTION;               \

    ex->print();                           \

    ShouldNotReachHere();                  \

  } (0

// ExceptionMark is a stack-allocated helper class for local exception handling.

// It is used with the EXCEPTION_MARK macro.

class ExceptionMark {

 private:

  Thread* _thread;

 public:

  ExceptionMark(Thread*& thread);

  ~ExceptionMark();

};

// Use an EXCEPTION_MARK for 'local' exceptions. EXCEPTION_MARK makes sure that no

// pending exception exists upon entering its scope and tests that no pending exception

// exists when leaving the scope.

// See also preserveException.hpp for PRESERVE_EXCEPTION_MARK macro,

// which preserves pre-existing exceptions and does not allow new

// exceptions.

#define EXCEPTION_MARK                           Thread* THREAD; ExceptionMark __em(THREAD);

#endif // SHARE_VM_UTILITIES_EXCEPTIONS_HPP