From b05b828eabc6b04c1c2e682048cb4187cc29a572 Mon Sep 17 00:00:00 2001
From: Steven Wu <stevenwu@apple.com>
Date: Thu, 7 May 2015 16:20:51 +0000
Subject: [PATCH] Fix another hang caused by ManagedStatic in SignalHandler

Fix two other variables that might cause the same hang fixed in r235914.
The hang is caused by constructing ManagedStatic in signalhandler. In
this case, if FileToRemove or CallBacksToRun is not contructed, it means
there is no work to do.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236741 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Support/Unix/Signals.inc | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/lib/Support/Unix/Signals.inc b/lib/Support/Unix/Signals.inc
index e7696c2f7ee..26fd5c3f4e6 100644
--- a/lib/Support/Unix/Signals.inc
+++ b/lib/Support/Unix/Signals.inc
@@ -139,6 +139,11 @@ static void UnregisterHandlers() {
 /// NB: This must be an async signal safe function. It cannot allocate or free
 /// memory, even in debug builds.
 static void RemoveFilesToRemove() {
+  // Avoid constructing ManagedStatic in the signal handler.
+  // If FilesToRemove is not constructed, there are no files to remove.
+  if (!FilesToRemove.isConstructed())
+    return;
+
   // We avoid iterators in case of debug iterators that allocate or release
   // memory.
   std::vector<std::string>& FilesToRemoveRef = *FilesToRemove;
@@ -200,10 +205,12 @@ static RETSIGTYPE SignalHandler(int Sig) {
   }
 
   // Otherwise if it is a fault (like SEGV) run any handler.
-  std::vector<std::pair<void (*)(void *), void *>>& CallBacksToRunRef =
-      *CallBacksToRun;
-  for (unsigned i = 0, e = CallBacksToRun->size(); i != e; ++i)
-    CallBacksToRunRef[i].first(CallBacksToRunRef[i].second);
+  if (CallBacksToRun.isConstructed()) {
+    std::vector<std::pair<void (*)(void *), void *>>& CallBacksToRunRef =
+        *CallBacksToRun;
+    for (unsigned i = 0, e = CallBacksToRun->size(); i != e; ++i)
+      CallBacksToRunRef[i].first(CallBacksToRunRef[i].second);
+  }
 
 #ifdef __s390__
   // On S/390, certain signals are delivered with PSW Address pointing to