/*
* Copyright 1998-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
// 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);
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);)
NOT_PRODUCT(static void debug_check_abort(const char *value_string);)
};
// 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)
// 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);