[Support] Optionally call signal handlers when a function wrapped by the the CrashRecoveryContext fails

This patch allows for handling a failure inside a CrashRecoveryContext in the same way as the global exception/signal handler. A failure will have the same side-effect, such as cleanup of temporarty file, printing callstack, calling relevant signal handlers, and finally returning an exception code. This is an optional feature, disabled by default.
This is a support patch for D69825.

Differential Revision: https://reviews.llvm.org/D70568

1 files changed, 52 insertions, 13 deletions

diff --git a/llvm/lib/Support/CrashRecoveryContext.cpp b/llvm/lib/Support/CrashRecoveryContext.cpp
index a9e0fcc73b9..548cce058c5 100644
--- a/llvm/lib/Support/CrashRecoveryContext.cpp
+++ b/llvm/lib/Support/CrashRecoveryContext.cpp
@@ -10,9 +10,17 @@
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/Signals.h"
 #include "llvm/Support/ThreadLocal.h"
 #include <mutex>
 #include <setjmp.h>
+#ifdef _WIN32
+#include <excpt.h> // for GetExceptionInformation
+#endif
+#if LLVM_ON_UNIX
+#include <sysexits.h> // EX_IOERR
+#endif
+
 using namespace llvm;
 
 namespace {
@@ -54,7 +62,11 @@ public:
 #endif
   }
 
-  void HandleCrash() {
+  // If the function ran by the CrashRecoveryContext crashes or fails, then
+  // 'RetCode' represents the returned error code, as if it was returned by a
+  // process. 'Context' represents the signal type on Unix; on Windows, it is
+  // the ExceptionContext.
+  void HandleCrash(int RetCode, uintptr_t Context) {
     // Eliminate the current context entry, to avoid re-entering in case the
     // cleanup code crashes.
     CurrentContext->set(Next);
@@ -62,7 +74,10 @@ public:
     assert(!Failed && "Crash recovery context already failed!");
     Failed = true;
 
-    // FIXME: Stash the backtrace.
+    if (CRC->DumpStackAndCleanupOnFailure)
+      sys::CleanupOnSignal(Context);
+
+    CRC->RetCode = RetCode;
 
     // Jump back to the RunSafely we were called under.
     longjmp(JumpBuffer, 1);
@@ -171,19 +186,32 @@ CrashRecoveryContext::unregisterCleanup(CrashRecoveryContextCleanup *cleanup) {
 static void installExceptionOrSignalHandlers() {}
 static void uninstallExceptionOrSignalHandlers() {}
 
-bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
-  if (!gCrashRecoveryEnabled) {
+// We need this function because the call to GetExceptionInformation() can only
+// occur inside the __except evaluation block
+static int ExceptionFilter(bool DumpStackAndCleanup,
+                           _EXCEPTION_POINTERS *Except) {
+  if (DumpStackAndCleanup)
+    sys::CleanupOnSignal((uintptr_t)Except);
+  return EXCEPTION_EXECUTE_HANDLER;
+}
+
+static bool InvokeFunctionCall(function_ref<void()> Fn,
+                               bool DumpStackAndCleanup, int &RetCode) {
+  __try {
     Fn();
-    return true;
+  } __except (ExceptionFilter(DumpStackAndCleanup, GetExceptionInformation())) {
+    RetCode = GetExceptionCode();
+    return false;
   }
+  return true;
+}
 
-  bool Result = true;
-  __try {
+bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
+  if (!gCrashRecoveryEnabled) {
     Fn();
-  } __except (1) { // Catch any exception.
-    Result = false;
+    return true;
   }
-  return Result;
+  return InvokeFunctionCall(Fn, DumpStackAndCleanupOnFailure, RetCode);
 }
 
 #else // !_MSC_VER
@@ -237,7 +265,8 @@ static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo)
   // implementation if we so choose.
 
   // Handle the crash
-  const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
+  const_cast<CrashRecoveryContextImpl *>(CRCI)->HandleCrash(
+      (int)ExceptionInfo->ExceptionRecord->ExceptionCode, ExceptionInfo);
 
   // Note that we don't actually get here because HandleCrash calls
   // longjmp, which means the HandleCrash function never returns.
@@ -319,8 +348,16 @@ static void CrashRecoverySignalHandler(int Signal) {
   sigaddset(&SigMask, Signal);
   sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
 
+  // As per convention, -2 indicates a crash or timeout as opposed to failure to
+  // execute (see llvm/include/llvm/Support/Program.h)
+  int RetCode = -2;
+
+  // Don't consider a broken pipe as a crash (see clang/lib/Driver/Driver.cpp)
+  if (Signal == SIGPIPE)
+    RetCode = EX_IOERR;
+
   if (CRCI)
-    const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
+    const_cast<CrashRecoveryContextImpl *>(CRCI)->HandleCrash(RetCode, Signal);
 }
 
 static void installExceptionOrSignalHandlers() {
@@ -364,7 +401,9 @@ bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
 void CrashRecoveryContext::HandleCrash() {
   CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
   assert(CRCI && "Crash recovery context never initialized!");
-  CRCI->HandleCrash();
+  // As per convention, -2 indicates a crash or timeout as opposed to failure to
+  // execute (see llvm/include/llvm/Support/Program.h)
+  CRCI->HandleCrash(-2, 0);
 }
 
 // FIXME: Portability.