5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
8 //  This file implements the "Exception Handling APIs"
15 #include <exception>        // for std::terminate
58 //  Get the exception object from the unwind pointer.
60 //  front of the user's exception object
115 static inline int incrementHandlerCount(__cxa_exception *exception) {  in incrementHandlerCount()  argument
116     return ++exception->handlerCount;  in incrementHandlerCount()
120 static inline  int decrementHandlerCount(__cxa_exception *exception) {  in decrementHandlerCount()  argument
121     return --exception->handlerCount;  in decrementHandlerCount()
127     exc is called, and then the memory for the exception is deallocated.
138     // Just in case there exists a dependent exception that is pointing to this,  in exception_cleanup_func()
145 //      * For purposes of this ABI, several things are considered exception handlers:  in failed_throw()
179 //  Reserve "thrown_size" bytes on the end for the user's exception
182 //  user's exception object.
242 //  It does not affect the reference count of the primary exception.  in __cxa_init_primary_exception()
248 // 2.4.3 Throwing the Exception Object  in __cxa_init_primary_exception()
250 After constructing the exception object with the throw argument value,  in __cxa_init_primary_exception()
256 * Obtain the __cxa_exception header from the thrown exception object address,  in __cxa_init_primary_exception()
267 pointer to the thrown exception, which __cxa_throw itself received as an argument.  in __cxa_init_primary_exception()
272 exception.  in __cxa_init_primary_exception()
285 …exception_header->referenceCount = 1; // This is a newly allocated exception, no need for thread s…  in __cxa_init_primary_exception()
303 // 2.5.3 Exception Handlers  in __cxa_init_primary_exception()
306   and saved in the exception header (either __cxa_exception or  in __cxa_init_primary_exception()
309   Requires:  exception is native  in __cxa_init_primary_exception()
344         // chain the foreign exception, terminate it.  in __cxa_init_primary_exception()
419 This routine can catch foreign or native exceptions.  If native, the exception  in __cxa_init_primary_exception()
421 ignorant of whether the native exception is primary or dependent.  in __cxa_init_primary_exception()
423 If the exception is native:  in __cxa_init_primary_exception()
424 * Increment's the exception's handler count.  in __cxa_init_primary_exception()
425 * Push the exception on the stack of currently-caught exceptions if it is not  in __cxa_init_primary_exception()
428 * Returns the adjusted pointer to the exception object, which is stored in  in __cxa_init_primary_exception()
431 If the exception is foreign, this means it did not originate from one of throw  in __cxa_init_primary_exception()
432 routines.  The foreign exception does not necessarily have a __cxa_exception  in __cxa_init_primary_exception()
435 * Do not try to increment the exception's handler count, we don't know where  in __cxa_init_primary_exception()
437 * Push the exception on the stack of currently-caught exceptions only if the  in __cxa_init_primary_exception()
438   stack is empty.  The foreign exception has no way to link to the current  in __cxa_init_primary_exception()
441   __cxa_exception block in front of the foreign exception.  It would be better  in __cxa_init_primary_exception()
446 * If we haven't terminated, assume the exception object is just past the  in __cxa_init_primary_exception()
455     // exception_header is a hackish offset from a foreign exception, but it  in __cxa_init_primary_exception()
465     // Remove the exception object from the linked list of exceptions that the z/OS unwinder  in __cxa_init_primary_exception()
467     // The libc++abi will manage the lifetime of the exception from this point forward.  in __cxa_init_primary_exception()
476         //  place the exception on the top of the stack if it's not already  in __cxa_init_primary_exception()
490     // Else this is a foreign exception  in __cxa_init_primary_exception()
494     // Push the foreign exception on to the stack  in __cxa_init_primary_exception()
504 This routine can be called for either a native or foreign exception.  in __cxa_init_primary_exception()
505 For a native exception:  in __cxa_init_primary_exception()
506 * Locates the most recently caught exception and decrements its handler count.  in __cxa_init_primary_exception()
507 * Removes the exception from the caught exception stack, if the handler count goes to zero.  in __cxa_init_primary_exception()
508 * If the handler count goes down to zero, and the exception was not re-thrown  in __cxa_init_primary_exception()
509   by throw, it locates the primary exception (which may be the same as the one  in __cxa_init_primary_exception()
511   goes to zero, the function destroys the exception. In any case, if the current  in __cxa_init_primary_exception()
512   exception is a dependent exception, it destroys that.  in __cxa_init_primary_exception()
514 For a foreign exception:  in __cxa_init_primary_exception()
516 * Otherwise delete the exception and pop the catch stack to empty.  in __cxa_init_primary_exception()
533     // If we've rethrown a foreign exception, then globals->caughtExceptions  in __cxa_init_primary_exception()
541             // This is a native exception  in __cxa_init_primary_exception()
544                 //  The exception has been rethrown by __cxa_rethrow, so don't delete it  in __cxa_init_primary_exception()
552                 //   that need to be told that this exception is rethrown.  Don't  in __cxa_init_primary_exception()
553                 //   erase this rethrow flag until the exception is recaught.  in __cxa_init_primary_exception()
557                 // The native exception has not been rethrown  in __cxa_init_primary_exception()
562                     // Destroy this exception, being careful to distinguish  in __cxa_init_primary_exception()
566 …               // Reset exception_header to primaryException and deallocate the dependent exception  in __cxa_init_primary_exception()
573                     // Destroy the primary exception only if its referenceCount goes to 0  in __cxa_init_primary_exception()
581             // The foreign exception has not been rethrown.  Pop the stack  in __cxa_init_primary_exception()
583             //    to touch a foreign exception in any way, that is undefined  in __cxa_init_primary_exception()
585             //     a foreign exception is with catch (...)!  in __cxa_init_primary_exception()
601 //  get the current exception  in __cxa_init_primary_exception()
607         return NULL;        //  No current exception  in __cxa_init_primary_exception()
615 If the exception is native:  in __cxa_init_primary_exception()
616 * marks the exception object on top of the caughtExceptions stack  in __cxa_init_primary_exception()
629         std::terminate();      // throw; called outside of a exception handler  in __cxa_init_primary_exception()
633         //  Mark the exception as being rethrown (reverse the effects of __cxa_begin_catch)  in __cxa_init_primary_exception()
636         //  __cxa_end_catch will remove this exception from the caughtExceptions stack if necessary  in __cxa_init_primary_exception()
638     else  // this is a foreign exception  in __cxa_init_primary_exception()
641         //   a foreign exception, so don't delete us, is to pop the stack here  in __cxa_init_primary_exception()
659     // Foreign exception: can't get exception_header->terminateHandler  in __cxa_init_primary_exception()
668     Requires:  If thrown_object is not NULL, it is a native exception.  in __cxa_init_primary_exception()
683     deallocate the exception.  in __cxa_init_primary_exception()
685     Requires:  If thrown_object is not NULL, it is a native exception.  in __cxa_init_primary_exception()
703     caughtExceptions stack.  Atomically increment the exception's referenceCount.  in __cxa_init_primary_exception()
709     the need to allocate the exception-handling globals.  in __cxa_init_primary_exception()
712 //  get the current exception  in __cxa_init_primary_exception()
715         return NULL;        //  If there are no globals, there is no exception  in __cxa_init_primary_exception()
718         return NULL;        //  No current exception  in __cxa_init_primary_exception()
720         return NULL;        // Can't capture a foreign exception (no way to refcount it)  in __cxa_init_primary_exception()
734     primary exception is decremented, destroying the primary if necessary.  in __cxa_init_primary_exception()
735     Finally the dependent exception is destroyed.  in __cxa_init_primary_exception()
751     exception.  in __cxa_init_primary_exception()