libunwind/src/Unwind-sjlj.c - rust-lang/llvm-project - Git at Google

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //
 //  Implements setjump-longjump based C++ exceptions
 //
 //===----------------------------------------------------------------------===//

 #include <unwind.h>

 #include <inttypes.h>
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdlib.h>

 #include "config.h"

 /// With SJLJ based exceptions, any function that has a catch clause or needs to
 /// do any clean up when an exception propagates through it, needs to call
 /// \c _Unwind_SjLj_Register at the start of the function and
 /// \c _Unwind_SjLj_Unregister at the end.  The register function is called with
 /// the address of a block of memory in the function's stack frame.  The runtime
 /// keeps a linked list (stack) of these blocks - one per thread.  The calling
 /// function also sets the personality and lsda fields of the block.

 #if defined(_LIBUNWIND_BUILD_SJLJ_APIS)

 struct _Unwind_FunctionContext {
   // next function in stack of handlers
   struct _Unwind_FunctionContext *prev;

 #if defined(__ve__)
   // VE requires to store 64 bit pointers in the buffer for SjLj execption.
   // We expand the size of values defined here.  This size must be matched
   // to the size returned by TargetMachine::getSjLjDataSize().

   // set by calling function before registering to be the landing pad
   uint64_t                        resumeLocation;

   // set by personality handler to be parameters passed to landing pad function
   uint64_t                        resumeParameters[4];
 #else
   // set by calling function before registering to be the landing pad
   uint32_t                        resumeLocation;

   // set by personality handler to be parameters passed to landing pad function
   uint32_t                        resumeParameters[4];
 #endif

   // set by calling function before registering
   _Unwind_Personality_Fn personality;          // arm offset=24
   uintptr_t                       lsda;        // arm offset=28

   // variable length array, contains registers to restore
   // 0 = r7, 1 = pc, 2 = sp
   void                           *jbuf[];
 };

 #if defined(_LIBUNWIND_HAS_NO_THREADS)
 # define _LIBUNWIND_THREAD_LOCAL
 #else
 # if __STDC_VERSION__ >= 201112L
 #  define _LIBUNWIND_THREAD_LOCAL _Thread_local
 # elif defined(_MSC_VER)
 #  define _LIBUNWIND_THREAD_LOCAL __declspec(thread)
 # elif defined(__GNUC__) || defined(__clang__)
 #  define _LIBUNWIND_THREAD_LOCAL __thread
 # else
 #  error Unable to create thread local storage
 # endif
 #endif


 #if !defined(FOR_DYLD)

 #if defined(__APPLE__)
 #include <System/pthread_machdep.h>
 #else
 static _LIBUNWIND_THREAD_LOCAL struct _Unwind_FunctionContext *stack = NULL;
 #endif

 static struct _Unwind_FunctionContext *__Unwind_SjLj_GetTopOfFunctionStack() {
 #if defined(__APPLE__)
   return _pthread_getspecific_direct(__PTK_LIBC_DYLD_Unwind_SjLj_Key);
 #else
   return stack;
 #endif
 }

 static void
 __Unwind_SjLj_SetTopOfFunctionStack(struct _Unwind_FunctionContext *fc) {
 #if defined(__APPLE__)
   _pthread_setspecific_direct(__PTK_LIBC_DYLD_Unwind_SjLj_Key, fc);
 #else
   stack = fc;
 #endif
 }

 #endif


 /// Called at start of each function that catches exceptions
 _LIBUNWIND_EXPORT void
 _Unwind_SjLj_Register(struct _Unwind_FunctionContext *fc) {
   fc->prev = __Unwind_SjLj_GetTopOfFunctionStack();
   __Unwind_SjLj_SetTopOfFunctionStack(fc);
 }


 /// Called at end of each function that catches exceptions
 _LIBUNWIND_EXPORT void
 _Unwind_SjLj_Unregister(struct _Unwind_FunctionContext *fc) {
   __Unwind_SjLj_SetTopOfFunctionStack(fc->prev);
 }


 static _Unwind_Reason_Code
 unwind_phase1(struct _Unwind_Exception *exception_object) {
   _Unwind_FunctionContext_t c = __Unwind_SjLj_GetTopOfFunctionStack();
   _LIBUNWIND_TRACE_UNWINDING("unwind_phase1: initial function-context=%p",
                              (void *)c);

   // walk each frame looking for a place to stop
   for (bool handlerNotFound = true; handlerNotFound; c = c->prev) {

     // check for no more frames
     if (c == NULL) {
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): reached "
                                  "bottom => _URC_END_OF_STACK",
                                  (void *)exception_object);
       return _URC_END_OF_STACK;
     }

     _LIBUNWIND_TRACE_UNWINDING("unwind_phase1: function-context=%p", (void *)c);
     // if there is a personality routine, ask it if it will want to stop at this
     // frame
     if (c->personality != NULL) {
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): calling "
                                  "personality function %p",
                                  (void *)exception_object,
                                  (void *)c->personality);
       _Unwind_Reason_Code personalityResult = (*c->personality)(
           1, _UA_SEARCH_PHASE, exception_object->exception_class,
           exception_object, (struct _Unwind_Context *)c);
       switch (personalityResult) {
       case _URC_HANDLER_FOUND:
         // found a catch clause or locals that need destructing in this frame
         // stop search and remember function context
         handlerNotFound = false;
         exception_object->private_2 = (uintptr_t) c;
         _LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): "
                                    "_URC_HANDLER_FOUND",
                                    (void *)exception_object);
         return _URC_NO_REASON;

       case _URC_CONTINUE_UNWIND:
         _LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): "
                                    "_URC_CONTINUE_UNWIND",
                                    (void *)exception_object);
         // continue unwinding
         break;

       default:
         // something went wrong
         _LIBUNWIND_TRACE_UNWINDING(
             "unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR",
             (void *)exception_object);
         return _URC_FATAL_PHASE1_ERROR;
       }
     }
   }
   return _URC_NO_REASON;
 }


 static _Unwind_Reason_Code
 unwind_phase2(struct _Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)",
                              (void *)exception_object);

   // walk each frame until we reach where search phase said to stop
   _Unwind_FunctionContext_t c = __Unwind_SjLj_GetTopOfFunctionStack();
   while (true) {
     _LIBUNWIND_TRACE_UNWINDING("unwind_phase2s(ex_ojb=%p): context=%p",
                                (void *)exception_object, (void *)c);

     // check for no more frames
     if (c == NULL) {
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2(ex_ojb=%p): __unw_step() reached "
           "bottom => _URC_END_OF_STACK",
           (void *)exception_object);
       return _URC_END_OF_STACK;
     }

     // if there is a personality routine, tell it we are unwinding
     if (c->personality != NULL) {
       _Unwind_Action action = _UA_CLEANUP_PHASE;
       if ((uintptr_t) c == exception_object->private_2)
         action = (_Unwind_Action)(
             _UA_CLEANUP_PHASE |
             _UA_HANDLER_FRAME); // tell personality this was the frame it marked
                                 // in phase 1
       _Unwind_Reason_Code personalityResult =
           (*c->personality)(1, action, exception_object->exception_class,
                             exception_object, (struct _Unwind_Context *)c);
       switch (personalityResult) {
       case _URC_CONTINUE_UNWIND:
         // continue unwinding
         _LIBUNWIND_TRACE_UNWINDING(
             "unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND",
             (void *)exception_object);
         if ((uintptr_t) c == exception_object->private_2) {
           // phase 1 said we would stop at this frame, but we did not...
           _LIBUNWIND_ABORT("during phase1 personality function said it would "
                            "stop here, but now if phase2 it did not stop here");
         }
         break;
       case _URC_INSTALL_CONTEXT:
         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): "
                                    "_URC_INSTALL_CONTEXT, will resume at "
                                    "landing pad %p",
                                    (void *)exception_object, c->jbuf[1]);
         // personality routine says to transfer control to landing pad
         // we may get control back if landing pad calls _Unwind_Resume()
         __Unwind_SjLj_SetTopOfFunctionStack(c);
         __builtin_longjmp(c->jbuf, 1);
         // __unw_resume() only returns if there was an error
         return _URC_FATAL_PHASE2_ERROR;
       default:
         // something went wrong
         _LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d",
                       personalityResult);
         return _URC_FATAL_PHASE2_ERROR;
       }
     }
     c = c->prev;
   }

   // clean up phase did not resume at the frame that the search phase said it
   // would
   return _URC_FATAL_PHASE2_ERROR;
 }


 static _Unwind_Reason_Code
 unwind_phase2_forced(struct _Unwind_Exception *exception_object,
                      _Unwind_Stop_Fn stop, void *stop_parameter) {
   // walk each frame until we reach where search phase said to stop
   _Unwind_FunctionContext_t c = __Unwind_SjLj_GetTopOfFunctionStack();
   while (true) {

     // get next frame (skip over first which is _Unwind_RaiseException)
     if (c == NULL) {
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2(ex_ojb=%p): __unw_step() reached "
           "bottom => _URC_END_OF_STACK",
           (void *)exception_object);
       return _URC_END_OF_STACK;
     }

     // call stop function at each frame
     _Unwind_Action action =
         (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE);
     _Unwind_Reason_Code stopResult =
         (*stop)(1, action, exception_object->exception_class, exception_object,
                 (struct _Unwind_Context *)c, stop_parameter);
     _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                "stop function returned %d",
                                (void *)exception_object, stopResult);
     if (stopResult != _URC_NO_REASON) {
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                  "stopped by stop function",
                                  (void *)exception_object);
       return _URC_FATAL_PHASE2_ERROR;
     }

     // if there is a personality routine, tell it we are unwinding
     if (c->personality != NULL) {
       _Unwind_Personality_Fn p = (_Unwind_Personality_Fn)c->personality;
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                  "calling personality function %p",
                                  (void *)exception_object, (void *)p);
       _Unwind_Reason_Code personalityResult =
           (*p)(1, action, exception_object->exception_class, exception_object,
                (struct _Unwind_Context *)c);
       switch (personalityResult) {
       case _URC_CONTINUE_UNWIND:
         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p):  "
                                    "personality returned _URC_CONTINUE_UNWIND",
                                    (void *)exception_object);
         // destructors called, continue unwinding
         break;
       case _URC_INSTALL_CONTEXT:
         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                    "personality returned _URC_INSTALL_CONTEXT",
                                    (void *)exception_object);
         // we may get control back if landing pad calls _Unwind_Resume()
         __Unwind_SjLj_SetTopOfFunctionStack(c);
         __builtin_longjmp(c->jbuf, 1);
         break;
       default:
         // something went wrong
         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                    "personality returned %d, "
                                    "_URC_FATAL_PHASE2_ERROR",
                                    (void *)exception_object, personalityResult);
         return _URC_FATAL_PHASE2_ERROR;
       }
     }
     c = c->prev;
   }

   // call stop function one last time and tell it we've reached the end of the
   // stack
   _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): calling stop "
                              "function with _UA_END_OF_STACK",
                              (void *)exception_object);
   _Unwind_Action lastAction =
       (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE | _UA_END_OF_STACK);
   (*stop)(1, lastAction, exception_object->exception_class, exception_object,
           (struct _Unwind_Context *)c, stop_parameter);

   // clean up phase did not resume at the frame that the search phase said it
   // would
   return _URC_FATAL_PHASE2_ERROR;
 }


 /// Called by __cxa_throw.  Only returns if there is a fatal error
 _LIBUNWIND_EXPORT _Unwind_Reason_Code
 _Unwind_SjLj_RaiseException(struct _Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("_Unwind_SjLj_RaiseException(ex_obj=%p)",
                        (void *)exception_object);

   // mark that this is a non-forced unwind, so _Unwind_Resume() can do the right
   // thing
   exception_object->private_1 = 0;
   exception_object->private_2 = 0;

   // phase 1: the search phase
   _Unwind_Reason_Code phase1 = unwind_phase1(exception_object);
   if (phase1 != _URC_NO_REASON)
     return phase1;

   // phase 2: the clean up phase
   return unwind_phase2(exception_object);
 }


 /// When _Unwind_RaiseException() is in phase2, it hands control
 /// to the personality function at each frame.  The personality
 /// may force a jump to a landing pad in that function, the landing
 /// pad code may then call _Unwind_Resume() to continue with the
 /// unwinding.  Note: the call to _Unwind_Resume() is from compiler
 /// geneated user code.  All other _Unwind_* routines are called
 /// by the C++ runtime __cxa_* routines.
 ///
 /// Re-throwing an exception is implemented by having the code call
 /// __cxa_rethrow() which in turn calls _Unwind_Resume_or_Rethrow()
 _LIBUNWIND_EXPORT void
 _Unwind_SjLj_Resume(struct _Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("_Unwind_SjLj_Resume(ex_obj=%p)",
                        (void *)exception_object);

   if (exception_object->private_1 != 0)
     unwind_phase2_forced(exception_object,
                          (_Unwind_Stop_Fn) exception_object->private_1,
                          (void *)exception_object->private_2);
   else
     unwind_phase2(exception_object);

   // clients assume _Unwind_Resume() does not return, so all we can do is abort.
   _LIBUNWIND_ABORT("_Unwind_SjLj_Resume() can't return");
 }


 ///  Called by __cxa_rethrow().
 _LIBUNWIND_EXPORT _Unwind_Reason_Code
 _Unwind_SjLj_Resume_or_Rethrow(struct _Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("__Unwind_SjLj_Resume_or_Rethrow(ex_obj=%p), "
                        "private_1=%" PRIuPTR,
                        (void *)exception_object, exception_object->private_1);
   // If this is non-forced and a stopping place was found, then this is a
   // re-throw.
   // Call _Unwind_RaiseException() as if this was a new exception.
   if (exception_object->private_1 == 0) {
     return _Unwind_SjLj_RaiseException(exception_object);
     // should return if there is no catch clause, so that __cxa_rethrow can call
     // std::terminate()
   }

   // Call through to _Unwind_Resume() which distiguishes between forced and
   // regular exceptions.
   _Unwind_SjLj_Resume(exception_object);
   _LIBUNWIND_ABORT("__Unwind_SjLj_Resume_or_Rethrow() called "
                     "_Unwind_SjLj_Resume() which unexpectedly returned");
 }


 /// Called by personality handler during phase 2 to get LSDA for current frame.
 _LIBUNWIND_EXPORT uintptr_t
 _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
   _Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
   _LIBUNWIND_TRACE_API("_Unwind_GetLanguageSpecificData(context=%p) "
                        "=> 0x%" PRIuPTR,
                        (void *)context, ufc->lsda);
   return ufc->lsda;
 }


 /// Called by personality handler during phase 2 to get register values.
 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetGR(struct _Unwind_Context *context,
                                           int index) {
   _LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d)", (void *)context,
                        index);
   _Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
   return ufc->resumeParameters[index];
 }


 /// Called by personality handler during phase 2 to alter register values.
 _LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index,
                                      uintptr_t new_value) {
   _LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%" PRIuPTR
                        ")",
                        (void *)context, index, new_value);
   _Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
   ufc->resumeParameters[index] = new_value;
 }


 /// Called by personality handler during phase 2 to get instruction pointer.
 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
   _Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
   _LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIu32,
                        (void *)context, ufc->resumeLocation + 1);
   return ufc->resumeLocation + 1;
 }


 /// Called by personality handler during phase 2 to get instruction pointer.
 /// ipBefore is a boolean that says if IP is already adjusted to be the call
 /// site address.  Normally IP is the return address.
 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,
                                               int *ipBefore) {
   _Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
   *ipBefore = 0;
   _LIBUNWIND_TRACE_API("_Unwind_GetIPInfo(context=%p, %p) => 0x%" PRIu32,
                        (void *)context, (void *)ipBefore,
                        ufc->resumeLocation + 1);
   return ufc->resumeLocation + 1;
 }


 /// Called by personality handler during phase 2 to alter instruction pointer.
 _LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
                                      uintptr_t new_value) {
   _LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%" PRIuPTR ")",
                        (void *)context, new_value);
   _Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
   ufc->resumeLocation = new_value - 1;
 }


 /// Called by personality handler during phase 2 to find the start of the
 /// function.
 _LIBUNWIND_EXPORT uintptr_t
 _Unwind_GetRegionStart(struct _Unwind_Context *context) {
   // Not supported or needed for sjlj based unwinding
   (void)context;
   _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p)", (void *)context);
   return 0;
 }


 /// Called by personality handler during phase 2 if a foreign exception
 /// is caught.
 _LIBUNWIND_EXPORT void
 _Unwind_DeleteException(struct _Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)",
                        (void *)exception_object);
   if (exception_object->exception_cleanup != NULL)
     (*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT,
                                            exception_object);
 }


 /// Called by personality handler during phase 2 to get base address for data
 /// relative encodings.
 _LIBUNWIND_EXPORT uintptr_t
 _Unwind_GetDataRelBase(struct _Unwind_Context *context) {
   // Not supported or needed for sjlj based unwinding
   (void)context;
   _LIBUNWIND_TRACE_API("_Unwind_GetDataRelBase(context=%p)", (void *)context);
   _LIBUNWIND_ABORT("_Unwind_GetDataRelBase() not implemented");
 }


 /// Called by personality handler during phase 2 to get base address for text
 /// relative encodings.
 _LIBUNWIND_EXPORT uintptr_t
 _Unwind_GetTextRelBase(struct _Unwind_Context *context) {
   // Not supported or needed for sjlj based unwinding
   (void)context;
   _LIBUNWIND_TRACE_API("_Unwind_GetTextRelBase(context=%p)", (void *)context);
   _LIBUNWIND_ABORT("_Unwind_GetTextRelBase() not implemented");
 }


 /// Called by personality handler to get "Call Frame Area" for current frame.
 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) {
   _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p)", (void *)context);
   if (context != NULL) {
     _Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
     // Setjmp/longjmp based exceptions don't have a true CFA.
     // Instead, the SP in the jmpbuf is the closest approximation.
     return (uintptr_t) ufc->jbuf[2];
   }
   return 0;
 }

 #endif // defined(_LIBUNWIND_BUILD_SJLJ_APIS)
	//===----------------------------------------------------------------------===//
	//
	// 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
	//
	//
	// Implements setjump-longjump based C++ exceptions
	//
	//===----------------------------------------------------------------------===//

	#include <unwind.h>

	#include <inttypes.h>
	#include <stdint.h>
	#include <stdbool.h>
	#include <stdlib.h>

	#include "config.h"

	/// With SJLJ based exceptions, any function that has a catch clause or needs to
	/// do any clean up when an exception propagates through it, needs to call
	/// \c _Unwind_SjLj_Register at the start of the function and
	/// \c _Unwind_SjLj_Unregister at the end. The register function is called with
	/// the address of a block of memory in the function's stack frame. The runtime
	/// keeps a linked list (stack) of these blocks - one per thread. The calling
	/// function also sets the personality and lsda fields of the block.

	#if defined(_LIBUNWIND_BUILD_SJLJ_APIS)

	struct _Unwind_FunctionContext {
	// next function in stack of handlers
	struct _Unwind_FunctionContext *prev;

	#if defined(__ve__)
	// VE requires to store 64 bit pointers in the buffer for SjLj execption.
	// We expand the size of values defined here. This size must be matched
	// to the size returned by TargetMachine::getSjLjDataSize().

	// set by calling function before registering to be the landing pad
	uint64_t resumeLocation;

	// set by personality handler to be parameters passed to landing pad function
	uint64_t resumeParameters[4];
	#else
	// set by calling function before registering to be the landing pad
	uint32_t resumeLocation;

	// set by personality handler to be parameters passed to landing pad function
	uint32_t resumeParameters[4];
	#endif

	// set by calling function before registering
	_Unwind_Personality_Fn personality; // arm offset=24
	uintptr_t lsda; // arm offset=28

	// variable length array, contains registers to restore
	// 0 = r7, 1 = pc, 2 = sp
	void *jbuf[];
	};

	#if defined(_LIBUNWIND_HAS_NO_THREADS)
	# define _LIBUNWIND_THREAD_LOCAL
	#else
	# if __STDC_VERSION__ >= 201112L
	# define _LIBUNWIND_THREAD_LOCAL _Thread_local
	# elif defined(_MSC_VER)
	# define _LIBUNWIND_THREAD_LOCAL __declspec(thread)
	# elif defined(__GNUC__) \|\| defined(__clang__)
	# define _LIBUNWIND_THREAD_LOCAL __thread
	# else
	# error Unable to create thread local storage
	# endif
	#endif


	#if !defined(FOR_DYLD)

	#if defined(__APPLE__)
	#include <System/pthread_machdep.h>
	#else
	static _LIBUNWIND_THREAD_LOCAL struct _Unwind_FunctionContext *stack = NULL;
	#endif

	static struct _Unwind_FunctionContext *__Unwind_SjLj_GetTopOfFunctionStack() {
	#if defined(__APPLE__)
	return _pthread_getspecific_direct(__PTK_LIBC_DYLD_Unwind_SjLj_Key);
	#else
	return stack;
	#endif
	}

	static void
	__Unwind_SjLj_SetTopOfFunctionStack(struct _Unwind_FunctionContext *fc) {
	#if defined(__APPLE__)
	_pthread_setspecific_direct(__PTK_LIBC_DYLD_Unwind_SjLj_Key, fc);
	#else
	stack = fc;
	#endif
	}

	#endif


	/// Called at start of each function that catches exceptions
	_LIBUNWIND_EXPORT void
	_Unwind_SjLj_Register(struct _Unwind_FunctionContext *fc) {
	fc->prev = __Unwind_SjLj_GetTopOfFunctionStack();
	__Unwind_SjLj_SetTopOfFunctionStack(fc);
	}


	/// Called at end of each function that catches exceptions
	_LIBUNWIND_EXPORT void
	_Unwind_SjLj_Unregister(struct _Unwind_FunctionContext *fc) {
	__Unwind_SjLj_SetTopOfFunctionStack(fc->prev);
	}


	static _Unwind_Reason_Code
	unwind_phase1(struct _Unwind_Exception *exception_object) {
	_Unwind_FunctionContext_t c = __Unwind_SjLj_GetTopOfFunctionStack();
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase1: initial function-context=%p",
	(void *)c);

	// walk each frame looking for a place to stop
	for (bool handlerNotFound = true; handlerNotFound; c = c->prev) {

	// check for no more frames
	if (c == NULL) {
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): reached "
	"bottom => _URC_END_OF_STACK",
	(void *)exception_object);
	return _URC_END_OF_STACK;
	}

	_LIBUNWIND_TRACE_UNWINDING("unwind_phase1: function-context=%p", (void *)c);
	// if there is a personality routine, ask it if it will want to stop at this
	// frame
	if (c->personality != NULL) {
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): calling "
	"personality function %p",
	(void *)exception_object,
	(void *)c->personality);
	_Unwind_Reason_Code personalityResult = (*c->personality)(
	1, _UA_SEARCH_PHASE, exception_object->exception_class,
	exception_object, (struct _Unwind_Context *)c);
	switch (personalityResult) {
	case _URC_HANDLER_FOUND:
	// found a catch clause or locals that need destructing in this frame
	// stop search and remember function context
	handlerNotFound = false;
	exception_object->private_2 = (uintptr_t) c;
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): "
	"_URC_HANDLER_FOUND",
	(void *)exception_object);
	return _URC_NO_REASON;

	case _URC_CONTINUE_UNWIND:
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): "
	"_URC_CONTINUE_UNWIND",
	(void *)exception_object);
	// continue unwinding
	break;

	default:
	// something went wrong
	_LIBUNWIND_TRACE_UNWINDING(
	"unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR",
	(void *)exception_object);
	return _URC_FATAL_PHASE1_ERROR;
	}
	}
	}
	return _URC_NO_REASON;
	}


	static _Unwind_Reason_Code
	unwind_phase2(struct _Unwind_Exception *exception_object) {
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)",
	(void *)exception_object);

	// walk each frame until we reach where search phase said to stop
	_Unwind_FunctionContext_t c = __Unwind_SjLj_GetTopOfFunctionStack();
	while (true) {
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2s(ex_ojb=%p): context=%p",
	(void )exception_object, (void )c);

	// check for no more frames
	if (c == NULL) {
	_LIBUNWIND_TRACE_UNWINDING(
	"unwind_phase2(ex_ojb=%p): __unw_step() reached "
	"bottom => _URC_END_OF_STACK",
	(void *)exception_object);
	return _URC_END_OF_STACK;
	}

	// if there is a personality routine, tell it we are unwinding
	if (c->personality != NULL) {
	_Unwind_Action action = _UA_CLEANUP_PHASE;
	if ((uintptr_t) c == exception_object->private_2)
	action = (_Unwind_Action)(
	_UA_CLEANUP_PHASE \|
	_UA_HANDLER_FRAME); // tell personality this was the frame it marked
	// in phase 1
	_Unwind_Reason_Code personalityResult =
	(*c->personality)(1, action, exception_object->exception_class,
	exception_object, (struct _Unwind_Context *)c);
	switch (personalityResult) {
	case _URC_CONTINUE_UNWIND:
	// continue unwinding
	_LIBUNWIND_TRACE_UNWINDING(
	"unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND",
	(void *)exception_object);
	if ((uintptr_t) c == exception_object->private_2) {
	// phase 1 said we would stop at this frame, but we did not...
	_LIBUNWIND_ABORT("during phase1 personality function said it would "
	"stop here, but now if phase2 it did not stop here");
	}
	break;
	case _URC_INSTALL_CONTEXT:
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): "
	"_URC_INSTALL_CONTEXT, will resume at "
	"landing pad %p",
	(void *)exception_object, c->jbuf[1]);
	// personality routine says to transfer control to landing pad
	// we may get control back if landing pad calls _Unwind_Resume()
	__Unwind_SjLj_SetTopOfFunctionStack(c);
	__builtin_longjmp(c->jbuf, 1);
	// __unw_resume() only returns if there was an error
	return _URC_FATAL_PHASE2_ERROR;
	default:
	// something went wrong
	_LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d",
	personalityResult);
	return _URC_FATAL_PHASE2_ERROR;
	}
	}
	c = c->prev;
	}

	// clean up phase did not resume at the frame that the search phase said it
	// would
	return _URC_FATAL_PHASE2_ERROR;
	}


	static _Unwind_Reason_Code
	unwind_phase2_forced(struct _Unwind_Exception *exception_object,
	_Unwind_Stop_Fn stop, void *stop_parameter) {
	// walk each frame until we reach where search phase said to stop
	_Unwind_FunctionContext_t c = __Unwind_SjLj_GetTopOfFunctionStack();
	while (true) {

	// get next frame (skip over first which is _Unwind_RaiseException)
	if (c == NULL) {
	_LIBUNWIND_TRACE_UNWINDING(
	"unwind_phase2(ex_ojb=%p): __unw_step() reached "
	"bottom => _URC_END_OF_STACK",
	(void *)exception_object);
	return _URC_END_OF_STACK;
	}

	// call stop function at each frame
	_Unwind_Action action =
	(_Unwind_Action)(_UA_FORCE_UNWIND \| _UA_CLEANUP_PHASE);
	_Unwind_Reason_Code stopResult =
	(*stop)(1, action, exception_object->exception_class, exception_object,
	(struct _Unwind_Context *)c, stop_parameter);
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
	"stop function returned %d",
	(void *)exception_object, stopResult);
	if (stopResult != _URC_NO_REASON) {
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
	"stopped by stop function",
	(void *)exception_object);
	return _URC_FATAL_PHASE2_ERROR;
	}

	// if there is a personality routine, tell it we are unwinding
	if (c->personality != NULL) {
	_Unwind_Personality_Fn p = (_Unwind_Personality_Fn)c->personality;
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
	"calling personality function %p",
	(void )exception_object, (void )p);
	_Unwind_Reason_Code personalityResult =
	(*p)(1, action, exception_object->exception_class, exception_object,
	(struct _Unwind_Context *)c);
	switch (personalityResult) {
	case _URC_CONTINUE_UNWIND:
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
	"personality returned _URC_CONTINUE_UNWIND",
	(void *)exception_object);
	// destructors called, continue unwinding
	break;
	case _URC_INSTALL_CONTEXT:
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
	"personality returned _URC_INSTALL_CONTEXT",
	(void *)exception_object);
	// we may get control back if landing pad calls _Unwind_Resume()
	__Unwind_SjLj_SetTopOfFunctionStack(c);
	__builtin_longjmp(c->jbuf, 1);
	break;
	default:
	// something went wrong
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
	"personality returned %d, "
	"_URC_FATAL_PHASE2_ERROR",
	(void *)exception_object, personalityResult);
	return _URC_FATAL_PHASE2_ERROR;
	}
	}
	c = c->prev;
	}

	// call stop function one last time and tell it we've reached the end of the
	// stack
	_LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): calling stop "
	"function with _UA_END_OF_STACK",
	(void *)exception_object);
	_Unwind_Action lastAction =
	(_Unwind_Action)(_UA_FORCE_UNWIND \| _UA_CLEANUP_PHASE \| _UA_END_OF_STACK);
	(*stop)(1, lastAction, exception_object->exception_class, exception_object,
	(struct _Unwind_Context *)c, stop_parameter);

	// clean up phase did not resume at the frame that the search phase said it
	// would
	return _URC_FATAL_PHASE2_ERROR;
	}


	/// Called by __cxa_throw. Only returns if there is a fatal error
	_LIBUNWIND_EXPORT _Unwind_Reason_Code
	_Unwind_SjLj_RaiseException(struct _Unwind_Exception *exception_object) {
	_LIBUNWIND_TRACE_API("_Unwind_SjLj_RaiseException(ex_obj=%p)",
	(void *)exception_object);

	// mark that this is a non-forced unwind, so _Unwind_Resume() can do the right
	// thing
	exception_object->private_1 = 0;
	exception_object->private_2 = 0;

	// phase 1: the search phase
	_Unwind_Reason_Code phase1 = unwind_phase1(exception_object);
	if (phase1 != _URC_NO_REASON)
	return phase1;

	// phase 2: the clean up phase
	return unwind_phase2(exception_object);
	}



	/// When _Unwind_RaiseException() is in phase2, it hands control
	/// to the personality function at each frame. The personality
	/// may force a jump to a landing pad in that function, the landing
	/// pad code may then call _Unwind_Resume() to continue with the
	/// unwinding. Note: the call to _Unwind_Resume() is from compiler
	/// geneated user code. All other _Unwind_* routines are called
	/// by the C++ runtime __cxa_* routines.
	///
	/// Re-throwing an exception is implemented by having the code call
	/// __cxa_rethrow() which in turn calls _Unwind_Resume_or_Rethrow()
	_LIBUNWIND_EXPORT void
	_Unwind_SjLj_Resume(struct _Unwind_Exception *exception_object) {
	_LIBUNWIND_TRACE_API("_Unwind_SjLj_Resume(ex_obj=%p)",
	(void *)exception_object);

	if (exception_object->private_1 != 0)
	unwind_phase2_forced(exception_object,
	(_Unwind_Stop_Fn) exception_object->private_1,
	(void *)exception_object->private_2);
	else
	unwind_phase2(exception_object);

	// clients assume _Unwind_Resume() does not return, so all we can do is abort.
	_LIBUNWIND_ABORT("_Unwind_SjLj_Resume() can't return");
	}


	/// Called by __cxa_rethrow().
	_LIBUNWIND_EXPORT _Unwind_Reason_Code
	_Unwind_SjLj_Resume_or_Rethrow(struct _Unwind_Exception *exception_object) {
	_LIBUNWIND_TRACE_API("__Unwind_SjLj_Resume_or_Rethrow(ex_obj=%p), "
	"private_1=%" PRIuPTR,
	(void *)exception_object, exception_object->private_1);
	// If this is non-forced and a stopping place was found, then this is a
	// re-throw.
	// Call _Unwind_RaiseException() as if this was a new exception.
	if (exception_object->private_1 == 0) {
	return _Unwind_SjLj_RaiseException(exception_object);
	// should return if there is no catch clause, so that __cxa_rethrow can call
	// std::terminate()
	}

	// Call through to _Unwind_Resume() which distiguishes between forced and
	// regular exceptions.
	_Unwind_SjLj_Resume(exception_object);
	_LIBUNWIND_ABORT("__Unwind_SjLj_Resume_or_Rethrow() called "
	"_Unwind_SjLj_Resume() which unexpectedly returned");
	}


	/// Called by personality handler during phase 2 to get LSDA for current frame.
	_LIBUNWIND_EXPORT uintptr_t
	_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
	_Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
	_LIBUNWIND_TRACE_API("_Unwind_GetLanguageSpecificData(context=%p) "
	"=> 0x%" PRIuPTR,
	(void *)context, ufc->lsda);
	return ufc->lsda;
	}


	/// Called by personality handler during phase 2 to get register values.
	_LIBUNWIND_EXPORT uintptr_t _Unwind_GetGR(struct _Unwind_Context *context,
	int index) {
	_LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d)", (void *)context,
	index);
	_Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
	return ufc->resumeParameters[index];
	}


	/// Called by personality handler during phase 2 to alter register values.
	_LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index,
	uintptr_t new_value) {
	_LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%" PRIuPTR
	")",
	(void *)context, index, new_value);
	_Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
	ufc->resumeParameters[index] = new_value;
	}


	/// Called by personality handler during phase 2 to get instruction pointer.
	_LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
	_Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
	_LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIu32,
	(void *)context, ufc->resumeLocation + 1);
	return ufc->resumeLocation + 1;
	}


	/// Called by personality handler during phase 2 to get instruction pointer.
	/// ipBefore is a boolean that says if IP is already adjusted to be the call
	/// site address. Normally IP is the return address.
	_LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,
	int *ipBefore) {
	_Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
	*ipBefore = 0;
	_LIBUNWIND_TRACE_API("_Unwind_GetIPInfo(context=%p, %p) => 0x%" PRIu32,
	(void )context, (void )ipBefore,
	ufc->resumeLocation + 1);
	return ufc->resumeLocation + 1;
	}


	/// Called by personality handler during phase 2 to alter instruction pointer.
	_LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
	uintptr_t new_value) {
	_LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%" PRIuPTR ")",
	(void *)context, new_value);
	_Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
	ufc->resumeLocation = new_value - 1;
	}


	/// Called by personality handler during phase 2 to find the start of the
	/// function.
	_LIBUNWIND_EXPORT uintptr_t
	_Unwind_GetRegionStart(struct _Unwind_Context *context) {
	// Not supported or needed for sjlj based unwinding
	(void)context;
	_LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p)", (void *)context);
	return 0;
	}


	/// Called by personality handler during phase 2 if a foreign exception
	/// is caught.
	_LIBUNWIND_EXPORT void
	_Unwind_DeleteException(struct _Unwind_Exception *exception_object) {
	_LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)",
	(void *)exception_object);
	if (exception_object->exception_cleanup != NULL)
	(*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT,
	exception_object);
	}



	/// Called by personality handler during phase 2 to get base address for data
	/// relative encodings.
	_LIBUNWIND_EXPORT uintptr_t
	_Unwind_GetDataRelBase(struct _Unwind_Context *context) {
	// Not supported or needed for sjlj based unwinding
	(void)context;
	_LIBUNWIND_TRACE_API("_Unwind_GetDataRelBase(context=%p)", (void *)context);
	_LIBUNWIND_ABORT("_Unwind_GetDataRelBase() not implemented");
	}


	/// Called by personality handler during phase 2 to get base address for text
	/// relative encodings.
	_LIBUNWIND_EXPORT uintptr_t
	_Unwind_GetTextRelBase(struct _Unwind_Context *context) {
	// Not supported or needed for sjlj based unwinding
	(void)context;
	_LIBUNWIND_TRACE_API("_Unwind_GetTextRelBase(context=%p)", (void *)context);
	_LIBUNWIND_ABORT("_Unwind_GetTextRelBase() not implemented");
	}


	/// Called by personality handler to get "Call Frame Area" for current frame.
	_LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) {
	_LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p)", (void *)context);
	if (context != NULL) {
	_Unwind_FunctionContext_t ufc = (_Unwind_FunctionContext_t) context;
	// Setjmp/longjmp based exceptions don't have a true CFA.
	// Instead, the SP in the jmpbuf is the closest approximation.
	return (uintptr_t) ufc->jbuf[2];
	}
	return 0;
	}

	#endif // defined(_LIBUNWIND_BUILD_SJLJ_APIS)