Fix _Unwind_Backtrace for libc++abi built with libgcc.

Implement an undocumented _US_FORCE_UNWIND flag for force
unwinding.

llvm-svn: 226820
This commit is contained in:
Logan Chien 2015-01-22 13:28:39 +00:00
parent 4947eb6e56
commit a713fce539
2 changed files with 14 additions and 0 deletions

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@ -63,6 +63,8 @@ typedef uint32_t _Unwind_State;
static const _Unwind_State _US_VIRTUAL_UNWIND_FRAME = 0;
static const _Unwind_State _US_UNWIND_FRAME_STARTING = 1;
static const _Unwind_State _US_UNWIND_FRAME_RESUME = 2;
/* Undocumented flag for force unwinding. */
static const _Unwind_State _US_FORCE_UNWIND = 8;
typedef uint32_t _Unwind_EHT_Header;

View File

@ -1101,9 +1101,16 @@ __gxx_personality_v0(_Unwind_State state,
_Unwind_SetGR(context, REG_UCB, reinterpret_cast<uint32_t>(unwind_exception));
#endif
// Check the undocumented force unwinding behavior
bool is_force_unwinding = state & _US_FORCE_UNWIND;
state &= ~_US_FORCE_UNWIND;
scan_results results;
switch (state) {
case _US_VIRTUAL_UNWIND_FRAME:
if (is_force_unwinding)
return continue_unwind(unwind_exception, context);
// Phase 1 search: All we're looking for in phase 1 is a handler that halts unwinding
scan_eh_tab(results, _UA_SEARCH_PHASE, native_exception, unwind_exception, context);
if (results.reason == _URC_HANDLER_FOUND)
@ -1119,6 +1126,11 @@ __gxx_personality_v0(_Unwind_State state,
return results.reason;
case _US_UNWIND_FRAME_STARTING:
// TODO: Support force unwinding in the phase 2 search.
// NOTE: In order to call the cleanup functions, _Unwind_ForcedUnwind()
// will call this personality function with (_US_FORCE_UNWIND |
// _US_UNWIND_FRAME_STARTING).
// Phase 2 search
if (unwind_exception->barrier_cache.sp == _Unwind_GetGR(context, REG_SP))
{