static ManagedStatic<sys::ThreadLocal<const CrashRecoveryContext>>
tlIsRecoveringFromCrash;
+static void installExceptionOrSignalHandlers();
+static void uninstallExceptionOrSignalHandlers();
+
CrashRecoveryContextCleanup::~CrashRecoveryContextCleanup() {}
CrashRecoveryContext::~CrashRecoveryContext() {
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)
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() {}
-// 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.
+bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
+ if (!gCrashRecoveryEnabled) {
+ Fn();
+ return true;
+ }
+
+ bool Result = true;
+ __try {
+ Fn();
+ } __except (1) { // Catch any exception.
+ Result = false;
+ }
+ return Result;
+}
+
+#else // !_MSC_VER
+
+#if defined(LLVM_ON_WIN32)
+// This is a non-MSVC compiler, probably mingw gcc or clang without
+// -fms-extensions. Use vectored exception handling (VEH).
+//
+// 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 exception handling is built on top of SEH, and so it
-// works on a per-thread basis.
+// 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)
{
// 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
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
}
}
-#else
+#else // !LLVM_ON_WIN32
// Generic POSIX implementation.
//
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;
}
}
-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.
return true;
}
+#endif // !_MSC_VER
+
void CrashRecoveryContext::HandleCrash() {
CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
assert(CRCI && "Crash recovery context never initialized!");
--- /dev/null
+//===- llvm/unittest/Support/CrashRecoveryTest.cpp ------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/CrashRecoveryContext.h"
+#include "llvm/Support/Compiler.h"
+#include "gtest/gtest.h"
+
+#ifdef LLVM_ON_WIN32
+#define WIN32_LEAN_AND_MEAN
+#define NOGDI
+#include <windows.h>
+#endif
+
+using namespace llvm;
+using namespace llvm::sys;
+
+static int GlobalInt = 0;
+static void nullDeref() { *(volatile int *)nullptr = 0; }
+static void incrementGlobal() { ++GlobalInt; }
+static void llvmTrap() { LLVM_BUILTIN_TRAP; }
+
+TEST(CrashRecoveryTest, Basic) {
+ llvm::CrashRecoveryContext::Enable();
+ GlobalInt = 0;
+ EXPECT_TRUE(CrashRecoveryContext().RunSafely(incrementGlobal));
+ EXPECT_EQ(1, GlobalInt);
+ EXPECT_FALSE(CrashRecoveryContext().RunSafely(nullDeref));
+ EXPECT_FALSE(CrashRecoveryContext().RunSafely(llvmTrap));
+}
+
+struct IncrementGlobalCleanup : CrashRecoveryContextCleanup {
+ IncrementGlobalCleanup(CrashRecoveryContext *CRC)
+ : CrashRecoveryContextCleanup(CRC) {}
+ virtual void recoverResources() { ++GlobalInt; }
+};
+
+static void noop() {}
+
+TEST(CrashRecoveryTest, Cleanup) {
+ llvm::CrashRecoveryContext::Enable();
+ GlobalInt = 0;
+ {
+ CrashRecoveryContext CRC;
+ CRC.registerCleanup(new IncrementGlobalCleanup(&CRC));
+ EXPECT_TRUE(CRC.RunSafely(noop));
+ } // run cleanups
+ EXPECT_EQ(1, GlobalInt);
+
+ GlobalInt = 0;
+ {
+ CrashRecoveryContext CRC;
+ CRC.registerCleanup(new IncrementGlobalCleanup(&CRC));
+ EXPECT_FALSE(CRC.RunSafely(nullDeref));
+ } // run cleanups
+ EXPECT_EQ(1, GlobalInt);
+}
+
+#ifdef LLVM_ON_WIN32
+static void raiseIt() {
+ RaiseException(123, EXCEPTION_NONCONTINUABLE, 0, NULL);
+}
+
+TEST(CrashRecoveryTest, RaiseException) {
+ llvm::CrashRecoveryContext::Enable();
+ EXPECT_FALSE(CrashRecoveryContext().RunSafely(raiseIt));
+}
+
+static void outputString() {
+ OutputDebugStringA("output for debugger\n");
+}
+
+TEST(CrashRecoveryTest, CallOutputDebugString) {
+ llvm::CrashRecoveryContext::Enable();
+ EXPECT_TRUE(CrashRecoveryContext().RunSafely(outputString));
+}
+
+#endif
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