intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 763 insertions, 0 deletions

diff --git a/contrib/libs/cxxsupp/libcxxabi/src/cxa_exception.cpp b/contrib/libs/cxxsupp/libcxxabi/src/cxa_exception.cpp
new file mode 100644
index 0000000000..36388d50da
--- /dev/null
+++ b/contrib/libs/cxxsupp/libcxxabi/src/cxa_exception.cpp
@@ -0,0 +1,763 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the "Exception Handling APIs"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
+//
+//===----------------------------------------------------------------------===//
+
+#include "cxxabi.h"
+
+#include <exception>        // for std::terminate
+#include <string.h>         // for memset
+#include "cxa_exception.h"
+#include "cxa_handlers.h"
+#include "fallback_malloc.h"
+#include "include/atomic_support.h" // from libc++
+
+#if __has_feature(address_sanitizer)
+#include <sanitizer/asan_interface.h>
+#endif
+
+// +---------------------------+-----------------------------+---------------+
+// | __cxa_exception           | _Unwind_Exception CLNGC++\0 | thrown object |
+// +---------------------------+-----------------------------+---------------+
+//                                                           ^
+//                                                           |
+//   +-------------------------------------------------------+
+//   |
+// +---------------------------+-----------------------------+
+// | __cxa_dependent_exception | _Unwind_Exception CLNGC++\1 |
+// +---------------------------+-----------------------------+
+
+namespace __cxxabiv1 {
+
+//  Utility routines
+static
+inline
+__cxa_exception*
+cxa_exception_from_thrown_object(void* thrown_object)
+{
+    return static_cast<__cxa_exception*>(thrown_object) - 1;
+}
+
+// Note:  This is never called when exception_header is masquerading as a
+//        __cxa_dependent_exception.
+static
+inline
+void*
+thrown_object_from_cxa_exception(__cxa_exception* exception_header)
+{
+    return static_cast<void*>(exception_header + 1);
+}
+
+//  Get the exception object from the unwind pointer.
+//  Relies on the structure layout, where the unwind pointer is right in
+//  front of the user's exception object
+static
+inline
+__cxa_exception*
+cxa_exception_from_exception_unwind_exception(_Unwind_Exception* unwind_exception)
+{
+    return cxa_exception_from_thrown_object(unwind_exception + 1 );
+}
+
+// Round s up to next multiple of a.
+static inline
+size_t aligned_allocation_size(size_t s, size_t a) {
+    return (s + a - 1) & ~(a - 1);
+}
+
+static inline
+size_t cxa_exception_size_from_exception_thrown_size(size_t size) {
+    return aligned_allocation_size(size + sizeof (__cxa_exception),
+                                   alignof(__cxa_exception));
+}
+
+void __setExceptionClass(_Unwind_Exception* unwind_exception, uint64_t newValue) {
+    ::memcpy(&unwind_exception->exception_class, &newValue, sizeof(newValue));
+}
+
+
+static void setOurExceptionClass(_Unwind_Exception* unwind_exception) {
+    __setExceptionClass(unwind_exception, kOurExceptionClass);
+}
+
+static void setDependentExceptionClass(_Unwind_Exception* unwind_exception) {
+    __setExceptionClass(unwind_exception, kOurDependentExceptionClass);
+}
+
+//  Is it one of ours?
+uint64_t __getExceptionClass(const _Unwind_Exception* unwind_exception) {
+    // On x86 and some ARM unwinders, unwind_exception->exception_class is
+    // a uint64_t. On other ARM unwinders, it is a char[8].
+    // See: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf
+    // So we just copy it into a uint64_t to be sure.
+    uint64_t exClass;
+    ::memcpy(&exClass, &unwind_exception->exception_class, sizeof(exClass));
+    return exClass;
+}
+
+bool __isOurExceptionClass(const _Unwind_Exception* unwind_exception) {
+    return (__getExceptionClass(unwind_exception) & get_vendor_and_language) ==
+           (kOurExceptionClass                    & get_vendor_and_language);
+}
+
+static bool isDependentException(_Unwind_Exception* unwind_exception) {
+    return (__getExceptionClass(unwind_exception) & 0xFF) == 0x01;
+}
+
+//  This does not need to be atomic
+static inline int incrementHandlerCount(__cxa_exception *exception) {
+    return ++exception->handlerCount;
+}
+
+//  This does not need to be atomic
+static inline  int decrementHandlerCount(__cxa_exception *exception) {
+    return --exception->handlerCount;
+}
+
+/*
+    If reason isn't _URC_FOREIGN_EXCEPTION_CAUGHT, then the terminateHandler
+    stored in exc is called.  Otherwise the exceptionDestructor stored in
+    exc is called, and then the memory for the exception is deallocated.
+
+    This is never called for a __cxa_dependent_exception.
+*/
+static
+void
+exception_cleanup_func(_Unwind_Reason_Code reason, _Unwind_Exception* unwind_exception)
+{
+    __cxa_exception* exception_header = cxa_exception_from_exception_unwind_exception(unwind_exception);
+    if (_URC_FOREIGN_EXCEPTION_CAUGHT != reason)
+        std::__terminate(exception_header->terminateHandler);
+    // Just in case there exists a dependent exception that is pointing to this,
+    //    check the reference count and only destroy this if that count goes to zero.
+    __cxa_decrement_exception_refcount(unwind_exception + 1);
+}
+
+static _LIBCXXABI_NORETURN void failed_throw(__cxa_exception* exception_header) {
+//  Section 2.5.3 says:
+//      * For purposes of this ABI, several things are considered exception handlers:
+//      ** A terminate() call due to a throw.
+//  and
+//      * Upon entry, Following initialization of the catch parameter,
+//          a handler must call:
+//      * void *__cxa_begin_catch(void *exceptionObject );
+    (void) __cxa_begin_catch(&exception_header->unwindHeader);
+    std::__terminate(exception_header->terminateHandler);
+}
+
+// Return the offset of the __cxa_exception header from the start of the
+// allocated buffer. If __cxa_exception's alignment is smaller than the maximum
+// useful alignment for the target machine, padding has to be inserted before
+// the header to ensure the thrown object that follows the header is
+// sufficiently aligned. This happens if _Unwind_exception isn't double-word
+// aligned (on Darwin, for example).
+static size_t get_cxa_exception_offset() {
+  struct S {
+  } __attribute__((aligned));
+
+  // Compute the maximum alignment for the target machine.
+  constexpr size_t alignment = alignof(S);
+  constexpr size_t excp_size = sizeof(__cxa_exception);
+  constexpr size_t aligned_size =
+      (excp_size + alignment - 1) / alignment * alignment;
+  constexpr size_t offset = aligned_size - excp_size;
+  static_assert((offset == 0 || alignof(_Unwind_Exception) < alignment),
+                "offset is non-zero only if _Unwind_Exception isn't aligned");
+  return offset;
+}
+
+extern "C" {
+
+//  Allocate a __cxa_exception object, and zero-fill it.
+//  Reserve "thrown_size" bytes on the end for the user's exception
+//  object. Zero-fill the object. If memory can't be allocated, call
+//  std::terminate. Return a pointer to the memory to be used for the
+//  user's exception object.
+void *__cxa_allocate_exception(size_t thrown_size) throw() {
+    size_t actual_size = cxa_exception_size_from_exception_thrown_size(thrown_size);
+
+    // Allocate extra space before the __cxa_exception header to ensure the
+    // start of the thrown object is sufficiently aligned.
+    size_t header_offset = get_cxa_exception_offset();
+    char *raw_buffer =
+        (char *)__aligned_malloc_with_fallback(header_offset + actual_size);
+    if (NULL == raw_buffer)
+        std::terminate();
+    __cxa_exception *exception_header =
+        static_cast<__cxa_exception *>((void *)(raw_buffer + header_offset));
+    ::memset(exception_header, 0, actual_size);
+    return thrown_object_from_cxa_exception(exception_header);
+}
+
+
+//  Free a __cxa_exception object allocated with __cxa_allocate_exception.
+void __cxa_free_exception(void *thrown_object) throw() {
+    // Compute the size of the padding before the header.
+    size_t header_offset = get_cxa_exception_offset();
+    char *raw_buffer =
+        ((char *)cxa_exception_from_thrown_object(thrown_object)) - header_offset;
+    __aligned_free_with_fallback((void *)raw_buffer);
+}
+
+
+//  This function shall allocate a __cxa_dependent_exception and
+//  return a pointer to it. (Really to the object, not past its' end).
+//  Otherwise, it will work like __cxa_allocate_exception.
+void * __cxa_allocate_dependent_exception () {
+    size_t actual_size = sizeof(__cxa_dependent_exception);
+    void *ptr = __aligned_malloc_with_fallback(actual_size);
+    if (NULL == ptr)
+        std::terminate();
+    ::memset(ptr, 0, actual_size);
+    return ptr;
+}
+
+
+//  This function shall free a dependent_exception.
+//  It does not affect the reference count of the primary exception.
+void __cxa_free_dependent_exception (void * dependent_exception) {
+    __aligned_free_with_fallback(dependent_exception);
+}
+
+
+// 2.4.3 Throwing the Exception Object
+/*
+After constructing the exception object with the throw argument value,
+the generated code calls the __cxa_throw runtime library routine. This
+routine never returns.
+
+The __cxa_throw routine will do the following:
+
+* Obtain the __cxa_exception header from the thrown exception object address,
+which can be computed as follows:
+ __cxa_exception *header = ((__cxa_exception *) thrown_exception - 1);
+* Save the current unexpected_handler and terminate_handler in the __cxa_exception header.
+* Save the tinfo and dest arguments in the __cxa_exception header.
+* Set the exception_class field in the unwind header. This is a 64-bit value
+representing the ASCII string "XXXXC++\0", where "XXXX" is a
+vendor-dependent string. That is, for implementations conforming to this
+ABI, the low-order 4 bytes of this 64-bit value will be "C++\0".
+* Increment the uncaught_exception flag.
+* Call _Unwind_RaiseException in the system unwind library, Its argument is the
+pointer to the thrown exception, which __cxa_throw itself received as an argument.
+__Unwind_RaiseException begins the process of stack unwinding, described
+in Section 2.5. In special cases, such as an inability to find a
+handler, _Unwind_RaiseException may return. In that case, __cxa_throw
+will call terminate, assuming that there was no handler for the
+exception.
+*/
+void
+__cxa_throw(void *thrown_object, std::type_info *tinfo, void (*dest)(void *)) {
+    __cxa_eh_globals *globals = __cxa_get_globals();
+    __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+
+    exception_header->unexpectedHandler = std::get_unexpected();
+    exception_header->terminateHandler  = std::get_terminate();
+    exception_header->exceptionType = tinfo;
+    exception_header->exceptionDestructor = dest;
+    setOurExceptionClass(&exception_header->unwindHeader);
+    exception_header->referenceCount = 1;  // This is a newly allocated exception, no need for thread safety.
+    globals->uncaughtExceptions += 1;   // Not atomically, since globals are thread-local
+
+    exception_header->unwindHeader.exception_cleanup = exception_cleanup_func;
+
+#if __has_feature(address_sanitizer)
+    // Inform the ASan runtime that now might be a good time to clean stuff up.
+    __asan_handle_no_return();
+#endif
+
+#ifdef __USING_SJLJ_EXCEPTIONS__
+    _Unwind_SjLj_RaiseException(&exception_header->unwindHeader);
+#else
+    _Unwind_RaiseException(&exception_header->unwindHeader);
+#endif
+    //  This only happens when there is no handler, or some unexpected unwinding
+    //     error happens.
+    failed_throw(exception_header);
+}
+
+
+// 2.5.3 Exception Handlers
+/*
+The adjusted pointer is computed by the personality routine during phase 1
+  and saved in the exception header (either __cxa_exception or
+  __cxa_dependent_exception).
+
+  Requires:  exception is native
+*/
+void *__cxa_get_exception_ptr(void *unwind_exception) throw() {
+#if defined(_LIBCXXABI_ARM_EHABI)
+    return reinterpret_cast<void*>(
+        static_cast<_Unwind_Control_Block*>(unwind_exception)->barrier_cache.bitpattern[0]);
+#else
+    return cxa_exception_from_exception_unwind_exception(
+        static_cast<_Unwind_Exception*>(unwind_exception))->adjustedPtr;
+#endif
+}
+
+#if defined(_LIBCXXABI_ARM_EHABI)
+/*
+The routine to be called before the cleanup.  This will save __cxa_exception in
+__cxa_eh_globals, so that __cxa_end_cleanup() can recover later.
+*/
+bool __cxa_begin_cleanup(void *unwind_arg) throw() {
+    _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(unwind_arg);
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    __cxa_exception* exception_header =
+        cxa_exception_from_exception_unwind_exception(unwind_exception);
+
+    if (__isOurExceptionClass(unwind_exception))
+    {
+        if (0 == exception_header->propagationCount)
+        {
+            exception_header->nextPropagatingException = globals->propagatingExceptions;
+            globals->propagatingExceptions = exception_header;
+        }
+        ++exception_header->propagationCount;
+    }
+    else
+    {
+        // If the propagatingExceptions stack is not empty, since we can't
+        // chain the foreign exception, terminate it.
+        if (NULL != globals->propagatingExceptions)
+            std::terminate();
+        globals->propagatingExceptions = exception_header;
+    }
+    return true;
+}
+
+/*
+The routine to be called after the cleanup has been performed.  It will get the
+propagating __cxa_exception from __cxa_eh_globals, and continue the stack
+unwinding with _Unwind_Resume.
+
+According to ARM EHABI 8.4.1, __cxa_end_cleanup() should not clobber any
+register, thus we have to write this function in assembly so that we can save
+{r1, r2, r3}.  We don't have to save r0 because it is the return value and the
+first argument to _Unwind_Resume().  In addition, we are saving lr in order to
+align the stack to 16 bytes and lr will be used to identify the caller and its
+frame information. _Unwind_Resume never return and we need to keep the original
+lr so just branch to it.
+*/
+__attribute__((used)) static _Unwind_Exception *
+__cxa_end_cleanup_impl()
+{
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    __cxa_exception* exception_header = globals->propagatingExceptions;
+    if (NULL == exception_header)
+    {
+        // It seems that __cxa_begin_cleanup() is not called properly.
+        // We have no choice but terminate the program now.
+        std::terminate();
+    }
+
+    if (__isOurExceptionClass(&exception_header->unwindHeader))
+    {
+        --exception_header->propagationCount;
+        if (0 == exception_header->propagationCount)
+        {
+            globals->propagatingExceptions = exception_header->nextPropagatingException;
+            exception_header->nextPropagatingException = NULL;
+        }
+    }
+    else
+    {
+        globals->propagatingExceptions = NULL;
+    }
+    return &exception_header->unwindHeader;
+}
+
+asm("	.pushsection	.text.__cxa_end_cleanup,\"ax\",%progbits\n"
+    "	.globl	__cxa_end_cleanup\n"
+    "	.type	__cxa_end_cleanup,%function\n"
+    "__cxa_end_cleanup:\n"
+#if defined(__ARM_FEATURE_BTI_DEFAULT)
+    "	bti\n"
+#endif
+    "	push	{r1, r2, r3, lr}\n"
+    "	bl	__cxa_end_cleanup_impl\n"
+    "	pop	{r1, r2, r3, r4}\n"
+    "	mov	lr, r4\n"
+#if defined(LIBCXXABI_BAREMETAL)
+    "	ldr	r4,	=_Unwind_Resume\n"
+    "	bx	r4\n"
+#else
+    "   b _Unwind_Resume\n"
+#endif
+    "	.popsection");
+#endif // defined(_LIBCXXABI_ARM_EHABI)
+
+/*
+This routine can catch foreign or native exceptions.  If native, the exception
+can be a primary or dependent variety.  This routine may remain blissfully
+ignorant of whether the native exception is primary or dependent.
+
+If the exception is native:
+* Increment's the exception's handler count.
+* Push the exception on the stack of currently-caught exceptions if it is not
+  already there (from a rethrow).
+* Decrements the uncaught_exception count.
+* Returns the adjusted pointer to the exception object, which is stored in
+  the __cxa_exception by the personality routine.
+
+If the exception is foreign, this means it did not originate from one of throw
+routines.  The foreign exception does not necessarily have a __cxa_exception
+header.  However we can catch it here with a catch (...), or with a call
+to terminate or unexpected during unwinding.
+* Do not try to increment the exception's handler count, we don't know where
+  it is.
+* Push the exception on the stack of currently-caught exceptions only if the
+  stack is empty.  The foreign exception has no way to link to the current
+  top of stack.  If the stack is not empty, call terminate.  Even with an
+  empty stack, this is hacked in by pushing a pointer to an imaginary
+  __cxa_exception block in front of the foreign exception.  It would be better
+  if the __cxa_eh_globals structure had a stack of _Unwind_Exception, but it
+  doesn't.  It has a stack of __cxa_exception (which has a next* in it).
+* Do not decrement the uncaught_exception count because we didn't increment it
+  in __cxa_throw (or one of our rethrow functions).
+* If we haven't terminated, assume the exception object is just past the
+  _Unwind_Exception and return a pointer to that.
+*/
+void*
+__cxa_begin_catch(void* unwind_arg) throw()
+{
+    _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(unwind_arg);
+    bool native_exception = __isOurExceptionClass(unwind_exception);
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    // exception_header is a hackish offset from a foreign exception, but it
+    //   works as long as we're careful not to try to access any __cxa_exception
+    //   parts.
+    __cxa_exception* exception_header =
+            cxa_exception_from_exception_unwind_exception
+            (
+                static_cast<_Unwind_Exception*>(unwind_exception)
+            );
+    if (native_exception)
+    {
+        // Increment the handler count, removing the flag about being rethrown
+        exception_header->handlerCount = exception_header->handlerCount < 0 ?
+            -exception_header->handlerCount + 1 : exception_header->handlerCount + 1;
+        //  place the exception on the top of the stack if it's not already
+        //    there by a previous rethrow
+        if (exception_header != globals->caughtExceptions)
+        {
+            exception_header->nextException = globals->caughtExceptions;
+            globals->caughtExceptions = exception_header;
+        }
+        globals->uncaughtExceptions -= 1;   // Not atomically, since globals are thread-local
+#if defined(_LIBCXXABI_ARM_EHABI)
+        return reinterpret_cast<void*>(exception_header->unwindHeader.barrier_cache.bitpattern[0]);
+#else
+        return exception_header->adjustedPtr;
+#endif
+    }
+    // Else this is a foreign exception
+    // If the caughtExceptions stack is not empty, terminate
+    if (globals->caughtExceptions != 0)
+        std::terminate();
+    // Push the foreign exception on to the stack
+    globals->caughtExceptions = exception_header;
+    return unwind_exception + 1;
+}
+
+
+/*
+Upon exit for any reason, a handler must call:
+    void __cxa_end_catch ();
+
+This routine can be called for either a native or foreign exception.
+For a native exception:
+* Locates the most recently caught exception and decrements its handler count.
+* Removes the exception from the caught exception stack, if the handler count goes to zero.
+* If the handler count goes down to zero, and the exception was not re-thrown
+  by throw, it locates the primary exception (which may be the same as the one
+  it's handling) and decrements its reference count. If that reference count
+  goes to zero, the function destroys the exception. In any case, if the current
+  exception is a dependent exception, it destroys that.
+
+For a foreign exception:
+* If it has been rethrown, there is nothing to do.
+* Otherwise delete the exception and pop the catch stack to empty.
+*/
+void __cxa_end_catch() {
+  static_assert(sizeof(__cxa_exception) == sizeof(__cxa_dependent_exception),
+                "sizeof(__cxa_exception) must be equal to "
+                "sizeof(__cxa_dependent_exception)");
+  static_assert(__builtin_offsetof(__cxa_exception, referenceCount) ==
+                    __builtin_offsetof(__cxa_dependent_exception,
+                                       primaryException),
+                "the layout of __cxa_exception must match the layout of "
+                "__cxa_dependent_exception");
+  static_assert(__builtin_offsetof(__cxa_exception, handlerCount) ==
+                    __builtin_offsetof(__cxa_dependent_exception, handlerCount),
+                "the layout of __cxa_exception must match the layout of "
+                "__cxa_dependent_exception");
+    __cxa_eh_globals* globals = __cxa_get_globals_fast(); // __cxa_get_globals called in __cxa_begin_catch
+    __cxa_exception* exception_header = globals->caughtExceptions;
+    // If we've rethrown a foreign exception, then globals->caughtExceptions
+    //    will have been made an empty stack by __cxa_rethrow() and there is
+    //    nothing more to be done.  Do nothing!
+    if (NULL != exception_header)
+    {
+        bool native_exception = __isOurExceptionClass(&exception_header->unwindHeader);
+        if (native_exception)
+        {
+            // This is a native exception
+            if (exception_header->handlerCount < 0)
+            {
+                //  The exception has been rethrown by __cxa_rethrow, so don't delete it
+                if (0 == incrementHandlerCount(exception_header))
+                {
+                    //  Remove from the chain of uncaught exceptions
+                    globals->caughtExceptions = exception_header->nextException;
+                    // but don't destroy
+                }
+                // Keep handlerCount negative in case there are nested catch's
+                //   that need to be told that this exception is rethrown.  Don't
+                //   erase this rethrow flag until the exception is recaught.
+            }
+            else
+            {
+                // The native exception has not been rethrown
+                if (0 == decrementHandlerCount(exception_header))
+                {
+                    //  Remove from the chain of uncaught exceptions
+                    globals->caughtExceptions = exception_header->nextException;
+                    // Destroy this exception, being careful to distinguish
+                    //    between dependent and primary exceptions
+                    if (isDependentException(&exception_header->unwindHeader))
+                    {
+                        // Reset exception_header to primaryException and deallocate the dependent exception
+                        __cxa_dependent_exception* dep_exception_header =
+                            reinterpret_cast<__cxa_dependent_exception*>(exception_header);
+                        exception_header =
+                            cxa_exception_from_thrown_object(dep_exception_header->primaryException);
+                        __cxa_free_dependent_exception(dep_exception_header);
+                    }
+                    // Destroy the primary exception only if its referenceCount goes to 0
+                    //    (this decrement must be atomic)
+                    __cxa_decrement_exception_refcount(thrown_object_from_cxa_exception(exception_header));
+                }
+            }
+        }
+        else
+        {
+            // The foreign exception has not been rethrown.  Pop the stack
+            //    and delete it.  If there are nested catch's and they try
+            //    to touch a foreign exception in any way, that is undefined
+            //     behavior.  They likely can't since the only way to catch
+            //     a foreign exception is with catch (...)!
+            _Unwind_DeleteException(&globals->caughtExceptions->unwindHeader);
+            globals->caughtExceptions = 0;
+        }
+    }
+}
+
+// Note:  exception_header may be masquerading as a __cxa_dependent_exception
+//        and that's ok.  exceptionType is there too.
+//        However watch out for foreign exceptions.  Return null for them.
+std::type_info *__cxa_current_exception_type() {
+//  get the current exception
+    __cxa_eh_globals *globals = __cxa_get_globals_fast();
+    if (NULL == globals)
+        return NULL;     //  If there have never been any exceptions, there are none now.
+    __cxa_exception *exception_header = globals->caughtExceptions;
+    if (NULL == exception_header)
+        return NULL;        //  No current exception
+    if (!__isOurExceptionClass(&exception_header->unwindHeader))
+        return NULL;
+    return exception_header->exceptionType;
+}
+
+// 2.5.4 Rethrowing Exceptions
+/*  This routine can rethrow native or foreign exceptions.
+If the exception is native:
+* marks the exception object on top of the caughtExceptions stack
+  (in an implementation-defined way) as being rethrown.
+* If the caughtExceptions stack is empty, it calls terminate()
+  (see [C++FDIS] [except.throw], 15.1.8).
+* It then calls _Unwind_RaiseException which should not return
+   (terminate if it does).
+  Note:  exception_header may be masquerading as a __cxa_dependent_exception
+         and that's ok.
+*/
+void __cxa_rethrow() {
+    __cxa_eh_globals* globals = __cxa_get_globals();
+    __cxa_exception* exception_header = globals->caughtExceptions;
+    if (NULL == exception_header)
+        std::terminate();      // throw; called outside of a exception handler
+    bool native_exception = __isOurExceptionClass(&exception_header->unwindHeader);
+    if (native_exception)
+    {
+        //  Mark the exception as being rethrown (reverse the effects of __cxa_begin_catch)
+        exception_header->handlerCount = -exception_header->handlerCount;
+        globals->uncaughtExceptions += 1;
+        //  __cxa_end_catch will remove this exception from the caughtExceptions stack if necessary
+    }
+    else  // this is a foreign exception
+    {
+        // The only way to communicate to __cxa_end_catch that we've rethrown
+        //   a foreign exception, so don't delete us, is to pop the stack here
+        //   which must be empty afterwards.  Then __cxa_end_catch will do
+        //   nothing
+        globals->caughtExceptions = 0;
+    }
+#ifdef __USING_SJLJ_EXCEPTIONS__
+    _Unwind_SjLj_RaiseException(&exception_header->unwindHeader);
+#else
+    _Unwind_RaiseException(&exception_header->unwindHeader);
+#endif
+
+    //  If we get here, some kind of unwinding error has occurred.
+    //  There is some weird code generation bug happening with
+    //     Apple clang version 4.0 (tags/Apple/clang-418.0.2) (based on LLVM 3.1svn)
+    //     If we call failed_throw here.  Turns up with -O2 or higher, and -Os.
+    __cxa_begin_catch(&exception_header->unwindHeader);
+    if (native_exception)
+        std::__terminate(exception_header->terminateHandler);
+    // Foreign exception: can't get exception_header->terminateHandler
+    std::terminate();
+}
+
+/*
+    If thrown_object is not null, atomically increment the referenceCount field
+    of the __cxa_exception header associated with the thrown object referred to
+    by thrown_object.
+
+    Requires:  If thrown_object is not NULL, it is a native exception.
+*/
+void
+__cxa_increment_exception_refcount(void *thrown_object) throw() {
+    if (thrown_object != NULL )
+    {
+        __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+        std::__libcpp_atomic_add(&exception_header->referenceCount, size_t(1));
+    }
+}
+
+/*
+    If thrown_object is not null, atomically decrement the referenceCount field
+    of the __cxa_exception header associated with the thrown object referred to
+    by thrown_object.  If the referenceCount drops to zero, destroy and
+    deallocate the exception.
+
+    Requires:  If thrown_object is not NULL, it is a native exception.
+*/
+_LIBCXXABI_NO_CFI
+void __cxa_decrement_exception_refcount(void *thrown_object) throw() {
+    if (thrown_object != NULL )
+    {
+        __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+        if (std::__libcpp_atomic_add(&exception_header->referenceCount, size_t(-1)) == 0)
+        {
+            if (NULL != exception_header->exceptionDestructor)
+                exception_header->exceptionDestructor(thrown_object);
+            __cxa_free_exception(thrown_object);
+        }
+    }
+}
+
+/*
+    Returns a pointer to the thrown object (if any) at the top of the
+    caughtExceptions stack.  Atomically increment the exception's referenceCount.
+    If there is no such thrown object or if the thrown object is foreign,
+    returns null.
+
+    We can use __cxa_get_globals_fast here to get the globals because if there have
+    been no exceptions thrown, ever, on this thread, we can return NULL without
+    the need to allocate the exception-handling globals.
+*/
+void *__cxa_current_primary_exception() throw() {
+//  get the current exception
+    __cxa_eh_globals* globals = __cxa_get_globals_fast();
+    if (NULL == globals)
+        return NULL;        //  If there are no globals, there is no exception
+    __cxa_exception* exception_header = globals->caughtExceptions;
+    if (NULL == exception_header)
+        return NULL;        //  No current exception
+    if (!__isOurExceptionClass(&exception_header->unwindHeader))
+        return NULL;        // Can't capture a foreign exception (no way to refcount it)
+    if (isDependentException(&exception_header->unwindHeader)) {
+        __cxa_dependent_exception* dep_exception_header =
+            reinterpret_cast<__cxa_dependent_exception*>(exception_header);
+        exception_header = cxa_exception_from_thrown_object(dep_exception_header->primaryException);
+    }
+    void* thrown_object = thrown_object_from_cxa_exception(exception_header);
+    __cxa_increment_exception_refcount(thrown_object);
+    return thrown_object;
+}
+
+/*
+    If reason isn't _URC_FOREIGN_EXCEPTION_CAUGHT, then the terminateHandler
+    stored in exc is called.  Otherwise the referenceCount stored in the
+    primary exception is decremented, destroying the primary if necessary.
+    Finally the dependent exception is destroyed.
+*/
+static
+void
+dependent_exception_cleanup(_Unwind_Reason_Code reason, _Unwind_Exception* unwind_exception)
+{
+    __cxa_dependent_exception* dep_exception_header =
+                      reinterpret_cast<__cxa_dependent_exception*>(unwind_exception + 1) - 1;
+    if (_URC_FOREIGN_EXCEPTION_CAUGHT != reason)
+        std::__terminate(dep_exception_header->terminateHandler);
+    __cxa_decrement_exception_refcount(dep_exception_header->primaryException);
+    __cxa_free_dependent_exception(dep_exception_header);
+}
+
+/*
+    If thrown_object is not null, allocate, initialize and throw a dependent
+    exception.
+*/
+void
+__cxa_rethrow_primary_exception(void* thrown_object)
+{
+    if ( thrown_object != NULL )
+    {
+        // thrown_object guaranteed to be native because
+        //   __cxa_current_primary_exception returns NULL for foreign exceptions
+        __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
+        __cxa_dependent_exception* dep_exception_header =
+            static_cast<__cxa_dependent_exception*>(__cxa_allocate_dependent_exception());
+        dep_exception_header->primaryException = thrown_object;
+        __cxa_increment_exception_refcount(thrown_object);
+        dep_exception_header->exceptionType = exception_header->exceptionType;
+        dep_exception_header->unexpectedHandler = std::get_unexpected();
+        dep_exception_header->terminateHandler = std::get_terminate();
+        setDependentExceptionClass(&dep_exception_header->unwindHeader);
+        __cxa_get_globals()->uncaughtExceptions += 1;
+        dep_exception_header->unwindHeader.exception_cleanup = dependent_exception_cleanup;
+#ifdef __USING_SJLJ_EXCEPTIONS__
+        _Unwind_SjLj_RaiseException(&dep_exception_header->unwindHeader);
+#else
+        _Unwind_RaiseException(&dep_exception_header->unwindHeader);
+#endif
+        // Some sort of unwinding error.  Note that terminate is a handler.
+        __cxa_begin_catch(&dep_exception_header->unwindHeader);
+    }
+    // If we return client will call terminate()
+}
+
+bool
+__cxa_uncaught_exception() throw() { return __cxa_uncaught_exceptions() != 0; }
+
+unsigned int
+__cxa_uncaught_exceptions() throw()
+{
+    // This does not report foreign exceptions in flight
+    __cxa_eh_globals* globals = __cxa_get_globals_fast();
+    if (globals == 0)
+        return 0;
+    return globals->uncaughtExceptions;
+}
+
+}  // extern "C"
+
+}  // abi