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 /*

  * Copyright (c) 1998, 2009, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * 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.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

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  */

 // 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 symbolHandle;

 class symbolOopDesc;

 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, symbolHandle 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,

                          symbolHandle name, const char* message, Handle loader,

                          Handle protection_domain);

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

                          symbolOop name, const char* message);

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

                          symbolHandle name, const char* message);

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

                           symbolHandle name, symbolHandle signature,

                           JavaCallArguments* args);

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

                          int line, symbolHandle 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,

                             symbolHandle 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, symbolHandle name,

                      const char* format, ...);

   // Create and initialize a new exception

   static Handle new_exception(Thread* thread, symbolHandle name,

                               symbolHandle signature, JavaCallArguments* args,

                               Handle cause, Handle loader,

                               Handle protection_domain);

   static Handle new_exception(Thread* thread, symbolHandle name,

                               const char* message, Handle cause, Handle loader,

                               Handle protection_domain,

                               ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);

  static Handle new_exception(Thread* thread, symbolOop 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);