shylie/llvm-project
1
0
Fork 0
Code Issues Pull Requests Actions 6 Packages Projects Releases Wiki Activity

[SystemZ][z/OS] Modify cxxabi to be compatible with existing z/OS runtime

Browse Source 
This patch is to enable exception handling on the z/OS platform that is compatible with the existing z/OS runtime. No functionality of libcxxabi has been changed for other platforms. With this patch the hope is we can add z/OS as a platform to perform testing on any C++ ABI changes.

There is a primary difference for the z/OS implementation. On z/OS the thrown object is added to a linked list of caught and uncaught exceptions. The unwinder uses the top one as the current exception it is trying to find the landing pad for. We have to pop the top exception after we get it’s landing pad for our unwinder to correctly get any subsequent rethrows or nested exception calls.

Differential Revision: https://reviews.llvm.org/D99913
This commit is contained in:
Muiez Ahmed 2022-06-28 20:59:49 +03:00
parent cfd474e0d0
commit 85593e7bb5
2 changed files with 12 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
libcxxabi/src/cxa_exception.cpp
View File

@ -444,6 +444,14 @@ __cxa_begin_catch(void* unwind_arg) throw()
(
static_cast<_Unwind_Exception*>(unwind_exception)
);
#if defined(__MVS__)
// Remove the exception object from the linked list of exceptions that the z/OS unwinder
// maintains before adding it to the libc++abi list of caught exceptions.
// The libc++abi will manage the lifetime of the exception from this point forward.
_UnwindZOS_PopException();
#endif
if (native_exception)
{
// Increment the handler count, removing the flag about being rethrown

6
libcxxabi/src/cxa_personality.cpp
View File

@ -622,7 +622,7 @@ static void scan_eh_tab(scan_results &results, _Unwind_Action actions,
results.reason = _URC_FATAL_PHASE1_ERROR;
return;
}
// Start scan by getting exception table address
// Start scan by getting exception table address.
const uint8_t *lsda = (const uint8_t *)_Unwind_GetLanguageSpecificData(context);
if (lsda == 0)
{
@ -912,6 +912,8 @@ static _Unwind_Reason_Code __gxx_personality_imp
_LIBCXXABI_FUNC_VIS _Unwind_Reason_Code
#ifdef __USING_SJLJ_EXCEPTIONS__
__gxx_personality_sj0
#elif defined(__MVS__)
__zos_cxx_personality_v2
#else
__gxx_personality_v0
#endif
@ -1121,7 +1123,7 @@ __gxx_personality_v0(_Unwind_State state,
}
// Either we didn't do a phase 1 search (due to forced unwinding), or
// phase 1 reported no catching-handlers.
// phase 1 reported no catching-handlers.
// Search for a (non-catching) cleanup
if (is_force_unwinding)
scan_eh_tab(