From 466c23b78a89940cf01be639409685db3f17b8ba Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Tue, 13 Sep 2011 21:13:29 +0000
Subject: [PATCH] Add a check to make sure schedulePass() has not deleted stale
 RequiredPass.

llvm-svn: 139642
---
 lib/VMCore/PassManager.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/VMCore/PassManager.cpp b/lib/VMCore/PassManager.cpp
index 34f37686362..ecedb1db66b 100644
--- a/lib/VMCore/PassManager.cpp
+++ b/lib/VMCore/PassManager.cpp
@@ -1634,9 +1634,11 @@ void MPPassManager::addLowerLevelRequiredPass(Pass *P, Pass *RequiredPass) {
   FPP->add(RequiredPass);
 
   // Register P as the last user of RequiredPass.
-  SmallVector<Pass *, 1> LU;
-  LU.push_back(RequiredPass);
-  FPP->setLastUser(LU,  P);
+  if (RequiredPass) {
+    SmallVector<Pass *, 1> LU;
+    LU.push_back(RequiredPass);
+    FPP->setLastUser(LU,  P);
+  }
 }
 
 /// Return function pass corresponding to PassInfo PI, that is