[Support] Ignore OutputDebugString exceptions in our crash recovery.

Zachary Turner · Zachary Turner · commit 13e87f43d9ed · 2017-05-16T22:50:32.000Z
Since we use AddVectoredExceptionHandler, we get notified of every exception that gets raised by a program. Sometimes these are not necessarily errors though, and this can be especially true when linking against a library that we have no control over, and may raise an exception internally which it intends to catch. In particular, the Windows API OutputDebugString does exactly this. It raises an exception inside of a __try / __except, giving the debugger a chance to handle the exception to print the message to the debug console. But this doesn't interoperate nicely with our vectored exception handler, which just sees another exception and decides that we need to terminate the program. Add a special case for this so that we ignore ODS exceptions and continue normally. Note that a better fix is to simply not use vectored exception handlers and use SEH instead, but given that MinGW doesn't support SEH, this is the only solution for MinGW. Differential Revision: https://reviews.llvm.org/D33260 llvm-svn: 303219
diff --git a/llvm/lib/Support/CrashRecoveryContext.cpp b/llvm/lib/Support/CrashRecoveryContext.cpp
@@ -164,6 +164,14 @@ CrashRecoveryContext::unregisterCleanup(CrashRecoveryContextCleanup *cleanup) {
 
 static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo)
 {
+  switch (ExceptionInfo->ExceptionRecord->ExceptionCode)
+  {
+  case DBG_PRINTEXCEPTION_C:
+  case DBG_PRINTEXCEPTION_WIDE_C:
+  case 0x406D1388:  // set debugger thread name
+    return EXCEPTION_CONTINUE_EXECUTION;
+  }
+
   // Lookup the current thread local recovery object.
   const CrashRecoveryContextImpl *CRCI = CurrentContext->get();
 
