diff options
Diffstat (limited to 'llvm/lib/Support/CrashRecoveryContext.cpp')
| -rw-r--r-- | llvm/lib/Support/CrashRecoveryContext.cpp | 114 |
1 files changed, 66 insertions, 48 deletions
diff --git a/llvm/lib/Support/CrashRecoveryContext.cpp b/llvm/lib/Support/CrashRecoveryContext.cpp index 6ebde46203f..1b0d452829b 100644 --- a/llvm/lib/Support/CrashRecoveryContext.cpp +++ b/llvm/lib/Support/CrashRecoveryContext.cpp @@ -78,6 +78,9 @@ static bool gCrashRecoveryEnabled = false; static ManagedStatic<sys::ThreadLocal<const CrashRecoveryContext>> tlIsRecoveringFromCrash; +static void installExceptionOrSignalHandlers(); +static void uninstallExceptionOrSignalHandlers(); + CrashRecoveryContextCleanup::~CrashRecoveryContextCleanup() {} CrashRecoveryContext::~CrashRecoveryContext() { @@ -113,6 +116,23 @@ CrashRecoveryContext *CrashRecoveryContext::GetCurrent() { return CRCI->CRC; } +void CrashRecoveryContext::Enable() { + sys::ScopedLock L(*gCrashRecoveryContextMutex); + // FIXME: Shouldn't this be a refcount or something? + if (gCrashRecoveryEnabled) + return; + gCrashRecoveryEnabled = true; + installExceptionOrSignalHandlers(); +} + +void CrashRecoveryContext::Disable() { + sys::ScopedLock L(*gCrashRecoveryContextMutex); + if (!gCrashRecoveryEnabled) + return; + gCrashRecoveryEnabled = false; + uninstallExceptionOrSignalHandlers(); +} + void CrashRecoveryContext::registerCleanup(CrashRecoveryContextCleanup *cleanup) { if (!cleanup) @@ -140,27 +160,51 @@ CrashRecoveryContext::unregisterCleanup(CrashRecoveryContextCleanup *cleanup) { delete cleanup; } -#ifdef LLVM_ON_WIN32 +#if defined(_MSC_VER) +// If _MSC_VER is defined, we must have SEH. Use it if it's available. It's way +// better than VEH. Vectored exception handling catches all exceptions happening +// on the thread with installed exception handlers, so it can interfere with +// internal exception handling of other libraries on that thread. SEH works +// exactly as you would expect normal exception handling to work: it only +// catches exceptions if they would bubble out from the stack frame with __try / +// __except. -#include "Windows/WindowsSupport.h" +static void installExceptionOrSignalHandlers() {} +static void uninstallExceptionOrSignalHandlers() {} + +bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) { + bool Result = true; + __try { + Fn(); + } __except (1) { // Catch any exception. + Result = false; + } + return Result; +} + +#else // !_MSC_VER -// On Windows, we can make use of vectored exception handling to -// catch most crashing situations. Note that this does mean -// we will be alerted of exceptions *before* structured exception -// handling has the opportunity to catch it. But that isn't likely -// to cause problems because nowhere in the project is SEH being -// used. +#if defined(LLVM_ON_WIN32) +// This is a non-MSVC compiler, probably mingw gcc or clang without +// -fms-extensions. Use vectored exception handling (VEH). // -// Vectored exception handling is built on top of SEH, and so it -// works on a per-thread basis. +// On Windows, we can make use of vectored exception handling to catch most +// crashing situations. Note that this does mean we will be alerted of +// exceptions *before* structured exception handling has the opportunity to +// catch it. Unfortunately, this causes problems in practice with other code +// running on threads with LLVM crash recovery contexts, so we would like to +// eventually move away from VEH. +// +// Vectored works on a per-thread basis, which is an advantage over +// SetUnhandledExceptionFilter. SetUnhandledExceptionFilter also doesn't have +// any native support for chaining exception handlers, but VEH allows more than +// one. // // The vectored exception handler functionality was added in Windows // XP, so if support for older versions of Windows is required, // it will have to be added. -// -// If we want to support as far back as Win2k, we could use the -// SetUnhandledExceptionFilter API, but there's a risk of that -// being entirely overwritten (it's not a chain). + +#include "Windows/WindowsSupport.h" static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo) { @@ -203,14 +247,7 @@ static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo) // non-NULL, valid VEH handles, or NULL. static sys::ThreadLocal<const void> sCurrentExceptionHandle; -void CrashRecoveryContext::Enable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = true; - +static void installExceptionOrSignalHandlers() { // We can set up vectored exception handling now. We will install our // handler as the front of the list, though there's no assurances that // it will remain at the front (another call could install itself before @@ -219,14 +256,7 @@ void CrashRecoveryContext::Enable() { sCurrentExceptionHandle.set(handle); } -void CrashRecoveryContext::Disable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (!gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = false; - +static void uninstallExceptionOrSignalHandlers() { PVOID currentHandle = const_cast<PVOID>(sCurrentExceptionHandle.get()); if (currentHandle) { // Now we can remove the vectored exception handler from the chain @@ -237,7 +267,7 @@ void CrashRecoveryContext::Disable() { } } -#else +#else // !LLVM_ON_WIN32 // Generic POSIX implementation. // @@ -289,14 +319,7 @@ static void CrashRecoverySignalHandler(int Signal) { const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash(); } -void CrashRecoveryContext::Enable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = true; - +static void installExceptionOrSignalHandlers() { // Setup the signal handler. struct sigaction Handler; Handler.sa_handler = CrashRecoverySignalHandler; @@ -308,20 +331,13 @@ void CrashRecoveryContext::Enable() { } } -void CrashRecoveryContext::Disable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (!gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = false; - +static void uninstallExceptionOrSignalHandlers() { // Restore the previous signal handlers. for (unsigned i = 0; i != NumSignals; ++i) sigaction(Signals[i], &PrevActions[i], nullptr); } -#endif +#endif // !LLVM_ON_WIN32 bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) { // If crash recovery is disabled, do nothing. @@ -339,6 +355,8 @@ bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) { return true; } +#endif // !_MSC_VER + void CrashRecoveryContext::HandleCrash() { CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl; assert(CRCI && "Crash recovery context never initialized!"); |
