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Imported Upstream version 5.18.0.207

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Former-commit-id: 3b152f462918d427ce18620a2cbe4f8b79650449
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Xamarin Public Jenkins (auto-signing)
2018-11-17 08:23:10 +00:00
parent 8e12397d70
commit eb85e2fc17
28480 changed files with 72 additions and 3866936 deletions
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412
external/llvm/lib/Support/CrashRecoveryContext.cpp vendored
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@ -1,412 +0,0 @@
//===--- CrashRecoveryContext.cpp - Crash Recovery ------------------------===//
//
// 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/Config/config.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Mutex.h"
#include "llvm/Support/ThreadLocal.h"
#include <setjmp.h>
using namespace llvm;
namespace {
struct CrashRecoveryContextImpl;
static ManagedStatic<
sys::ThreadLocal<const CrashRecoveryContextImpl> > CurrentContext;
struct CrashRecoveryContextImpl {
// When threads are disabled, this links up all active
// CrashRecoveryContextImpls. When threads are enabled there's one thread
// per CrashRecoveryContext and CurrentContext is a thread-local, so only one
// CrashRecoveryContextImpl is active per thread and this is always null.
const CrashRecoveryContextImpl *Next;
CrashRecoveryContext *CRC;
::jmp_buf JumpBuffer;
volatile unsigned Failed : 1;
unsigned SwitchedThread : 1;
public:
CrashRecoveryContextImpl(CrashRecoveryContext *CRC) : CRC(CRC),
Failed(false),
SwitchedThread(false) {
Next = CurrentContext->get();
CurrentContext->set(this);
}
~CrashRecoveryContextImpl() {
if (!SwitchedThread)
CurrentContext->set(Next);
}
/// \brief Called when the separate crash-recovery thread was finished, to
/// indicate that we don't need to clear the thread-local CurrentContext.
void setSwitchedThread() {
#if defined(LLVM_ENABLE_THREADS) && LLVM_ENABLE_THREADS != 0
SwitchedThread = true;
#endif
}
void HandleCrash() {
// Eliminate the current context entry, to avoid re-entering in case the
// cleanup code crashes.
CurrentContext->set(Next);
assert(!Failed && "Crash recovery context already failed!");
Failed = true;
// FIXME: Stash the backtrace.
// Jump back to the RunSafely we were called under.
longjmp(JumpBuffer, 1);
}
};
}
static ManagedStatic<sys::Mutex> gCrashRecoveryContextMutex;
static bool gCrashRecoveryEnabled = false;
static ManagedStatic<sys::ThreadLocal<const CrashRecoveryContext>>
tlIsRecoveringFromCrash;
static void installExceptionOrSignalHandlers();
static void uninstallExceptionOrSignalHandlers();
CrashRecoveryContextCleanup::~CrashRecoveryContextCleanup() {}
CrashRecoveryContext::~CrashRecoveryContext() {
// Reclaim registered resources.
CrashRecoveryContextCleanup *i = head;
const CrashRecoveryContext *PC = tlIsRecoveringFromCrash->get();
tlIsRecoveringFromCrash->set(this);
while (i) {
CrashRecoveryContextCleanup *tmp = i;
i = tmp->next;
tmp->cleanupFired = true;
tmp->recoverResources();
delete tmp;
}
tlIsRecoveringFromCrash->set(PC);
CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
delete CRCI;
}
bool CrashRecoveryContext::isRecoveringFromCrash() {
return tlIsRecoveringFromCrash->get() != nullptr;
}
CrashRecoveryContext *CrashRecoveryContext::GetCurrent() {
if (!gCrashRecoveryEnabled)
return nullptr;
const CrashRecoveryContextImpl *CRCI = CurrentContext->get();
if (!CRCI)
return nullptr;
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)
return;
if (head)
head->prev = cleanup;
cleanup->next = head;
head = cleanup;
}
void
CrashRecoveryContext::unregisterCleanup(CrashRecoveryContextCleanup *cleanup) {
if (!cleanup)
return;
if (cleanup == head) {
head = cleanup->next;
if (head)
head->prev = nullptr;
}
else {
cleanup->prev->next = cleanup->next;
if (cleanup->next)
cleanup->next->prev = cleanup->prev;
}
delete cleanup;
}
#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.
static void installExceptionOrSignalHandlers() {}
static void uninstallExceptionOrSignalHandlers() {}
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 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.
#include "Windows/WindowsSupport.h"
static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo)
{
// DBG_PRINTEXCEPTION_WIDE_C is not properly defined on all supported
// compilers and platforms, so we define it manually.
constexpr ULONG DbgPrintExceptionWideC = 0x4001000AL;
switch (ExceptionInfo->ExceptionRecord->ExceptionCode)
{
case DBG_PRINTEXCEPTION_C:
case DbgPrintExceptionWideC:
case 0x406D1388: // set debugger thread name
return EXCEPTION_CONTINUE_EXECUTION;
}
// Lookup the current thread local recovery object.
const CrashRecoveryContextImpl *CRCI = CurrentContext->get();
if (!CRCI) {
// Something has gone horribly wrong, so let's just tell everyone
// to keep searching
CrashRecoveryContext::Disable();
return EXCEPTION_CONTINUE_SEARCH;
}
// TODO: We can capture the stack backtrace here and store it on the
// implementation if we so choose.
// Handle the crash
const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
// Note that we don't actually get here because HandleCrash calls
// longjmp, which means the HandleCrash function never returns.
llvm_unreachable("Handled the crash, should have longjmp'ed out of here");
}
// Because the Enable and Disable calls are static, it means that
// there may not actually be an Impl available, or even a current
// CrashRecoveryContext at all. So we make use of a thread-local
// exception table. The handles contained in here will either be
// non-NULL, valid VEH handles, or NULL.
static sys::ThreadLocal<const void> sCurrentExceptionHandle;
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
// our handler). This 1) isn't likely, and 2) shouldn't cause problems.
PVOID handle = ::AddVectoredExceptionHandler(1, ExceptionHandler);
sCurrentExceptionHandle.set(handle);
}
static void uninstallExceptionOrSignalHandlers() {
PVOID currentHandle = const_cast<PVOID>(sCurrentExceptionHandle.get());
if (currentHandle) {
// Now we can remove the vectored exception handler from the chain
::RemoveVectoredExceptionHandler(currentHandle);
// Reset the handle in our thread-local set.
sCurrentExceptionHandle.set(NULL);
}
}
#else // !LLVM_ON_WIN32
// Generic POSIX implementation.
//
// This implementation relies on synchronous signals being delivered to the
// current thread. We use a thread local object to keep track of the active
// crash recovery context, and install signal handlers to invoke HandleCrash on
// the active object.
//
// This implementation does not to attempt to chain signal handlers in any
// reliable fashion -- if we get a signal outside of a crash recovery context we
// simply disable crash recovery and raise the signal again.
#include <signal.h>
static const int Signals[] =
{ SIGABRT, SIGBUS, SIGFPE, SIGILL, SIGSEGV, SIGTRAP };
static const unsigned NumSignals = array_lengthof(Signals);
static struct sigaction PrevActions[NumSignals];
static void CrashRecoverySignalHandler(int Signal) {
// Lookup the current thread local recovery object.
const CrashRecoveryContextImpl *CRCI = CurrentContext->get();
if (!CRCI) {
// We didn't find a crash recovery context -- this means either we got a
// signal on a thread we didn't expect it on, the application got a signal
// outside of a crash recovery context, or something else went horribly
// wrong.
//
// Disable crash recovery and raise the signal again. The assumption here is
// that the enclosing application will terminate soon, and we won't want to
// attempt crash recovery again.
//
// This call of Disable isn't thread safe, but it doesn't actually matter.
CrashRecoveryContext::Disable();
raise(Signal);
// The signal will be thrown once the signal mask is restored.
return;
}
// Unblock the signal we received.
sigset_t SigMask;
sigemptyset(&SigMask);
sigaddset(&SigMask, Signal);
sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
if (CRCI)
const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
}
static void installExceptionOrSignalHandlers() {
// Setup the signal handler.
struct sigaction Handler;
Handler.sa_handler = CrashRecoverySignalHandler;
Handler.sa_flags = 0;
sigemptyset(&Handler.sa_mask);
for (unsigned i = 0; i != NumSignals; ++i) {
sigaction(Signals[i], &Handler, &PrevActions[i]);
}
}
static void uninstallExceptionOrSignalHandlers() {
// Restore the previous signal handlers.
for (unsigned i = 0; i != NumSignals; ++i)
sigaction(Signals[i], &PrevActions[i], nullptr);
}
#endif // !LLVM_ON_WIN32
bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
// If crash recovery is disabled, do nothing.
if (gCrashRecoveryEnabled) {
assert(!Impl && "Crash recovery context already initialized!");
CrashRecoveryContextImpl *CRCI = new CrashRecoveryContextImpl(this);
Impl = CRCI;
if (setjmp(CRCI->JumpBuffer) != 0) {
return false;
}
}
Fn();
return true;
}
#endif // !_MSC_VER
void CrashRecoveryContext::HandleCrash() {
CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
assert(CRCI && "Crash recovery context never initialized!");
CRCI->HandleCrash();
}
// FIXME: Portability.
static void setThreadBackgroundPriority() {
#ifdef __APPLE__
setpriority(PRIO_DARWIN_THREAD, 0, PRIO_DARWIN_BG);
#endif
}
static bool hasThreadBackgroundPriority() {
#ifdef __APPLE__
return getpriority(PRIO_DARWIN_THREAD, 0) == 1;
#else
return false;
#endif
}
namespace {
struct RunSafelyOnThreadInfo {
function_ref<void()> Fn;
CrashRecoveryContext *CRC;
bool UseBackgroundPriority;
bool Result;
};
}
static void RunSafelyOnThread_Dispatch(void *UserData) {
RunSafelyOnThreadInfo *Info =
reinterpret_cast<RunSafelyOnThreadInfo*>(UserData);
if (Info->UseBackgroundPriority)
setThreadBackgroundPriority();
Info->Result = Info->CRC->RunSafely(Info->Fn);
}
bool CrashRecoveryContext::RunSafelyOnThread(function_ref<void()> Fn,
unsigned RequestedStackSize) {
bool UseBackgroundPriority = hasThreadBackgroundPriority();
RunSafelyOnThreadInfo Info = { Fn, this, UseBackgroundPriority, false };
llvm_execute_on_thread(RunSafelyOnThread_Dispatch, &Info, RequestedStackSize);
if (CrashRecoveryContextImpl *CRC = (CrashRecoveryContextImpl *)Impl)
CRC->setSwitchedThread();
return Info.Result;
}