[PATCH] D147739: [libunwind] [SEH] Handle ExceptionContinueExecution in forced unwinding

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo created this revision.
mstorsjo added a reviewer: cdavis5x.
Herald added projects: libunwind, All.
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This fixes the libcxxabi test force_unwind3.pass.cpp when run on native
Windows.

When unwinding past the main thread function into the system functions
that brought up the thread, we can hit functions whose personality
functions return ExceptionContinueExecution (instead of the regular
ExceptionContinueSearch). Interpret this as a signal to stop the
unwind.

Curiously, in this case, it does return ExceptionContinueSearch if
running within a debugger.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D147739

Files:
  libunwind/src/Unwind-seh.cpp


Index: libunwind/src/Unwind-seh.cpp
===================================================================
--- libunwind/src/Unwind-seh.cpp
+++ libunwind/src/Unwind-seh.cpp
@@ -217,6 +217,7 @@
                                                            disp_ctx->ContextRecord,
                                                            disp_ctx);
   switch (ms_act) {
+  case ExceptionContinueExecution: return _URC_END_OF_STACK;
   case ExceptionContinueSearch: return _URC_CONTINUE_UNWIND;
   case 4 /*ExceptionExecuteHandler*/:
     return phase2 ? _URC_INSTALL_CONTEXT : _URC_HANDLER_FOUND;
@@ -304,6 +305,12 @@
         // We may get control back if landing pad calls _Unwind_Resume().
         __unw_resume(&cursor2);
         break;
+      case _URC_END_OF_STACK:
+        _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
+                                   "personality returned "
+                                   "_URC_END_OF_STACK",
+                                   (void *)exception_object);
+        break;
       default:
         // Personality routine returned an unknown result code.
         _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
@@ -312,6 +319,8 @@
                                    (void *)exception_object, personalityResult);
         return _URC_FATAL_PHASE2_ERROR;
       }
+      if (personalityResult == _URC_END_OF_STACK)
+        break;
     }
   }
 


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