Support: Add CrashRecoveryContext helper object.

- Designed as a simple wrapper to allow clients to attempt to catch crashes
   (memory errors, assertion violations, etc.) and do some kind of recovery.

 - Currently doesn't actually attempt to catch crashes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109586 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/CrashRecoveryContext.cpp

@@ -0,0 +1,88 @@
+//===--- 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/ADT/SmallString.h"
+#include <setjmp.h>
+using namespace llvm;
+
+namespace {
+
+struct CrashRecoveryContextImpl;
+
+struct CrashRecoveryContextImpl {
+  std::string Backtrace;
+  ::jmp_buf JumpBuffer;
+  volatile unsigned Failed : 1;
+
+public:
+  CrashRecoveryContextImpl() : Failed(false) {}
+
+  void HandleCrash() {
+    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 bool gCrashRecoveryEnabled = false;
+
+CrashRecoveryContext::~CrashRecoveryContext() {
+  CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
+  delete CRCI;
+}
+
+void CrashRecoveryContext::Enable() {
+  if (gCrashRecoveryEnabled)
+    return;
+
+  gCrashRecoveryEnabled = true;
+}
+
+void CrashRecoveryContext::Disable() {
+  if (!gCrashRecoveryEnabled)
+    return;
+
+  gCrashRecoveryEnabled = false;
+}
+
+bool CrashRecoveryContext::RunSafely(void (*Fn)(void*), void *UserData) {
+  // If crash recovery is disabled, do nothing.
+  if (gCrashRecoveryEnabled) {
+    assert(!Impl && "Crash recovery context already initialized!");
+    CrashRecoveryContextImpl *CRCI = new CrashRecoveryContextImpl;
+    Impl = CRCI;
+
+    if (setjmp(CRCI->JumpBuffer) != 0) {
+      return false;
+    }
+  }
+
+  Fn(UserData);
+  return true;
+}
+
+void CrashRecoveryContext::HandleCrash() {
+  CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
+  assert(CRCI && "Crash recovery context never initialized!");
+  CRCI->HandleCrash();
+}
+
+const std::string &CrashRecoveryContext::getBacktrace() const {
+  CrashRecoveryContextImpl *CRC = (CrashRecoveryContextImpl *) Impl;
+  assert(CRC && "Crash recovery context never initialized!");
+  assert(CRC->Failed && "No crash was detected!");
+  return CRC->Backtrace;
+}