From c67d184a2bd24ee827479db5556fbaaac0bc9507 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Tue, 13 Sep 2011 21:13:29 +0000
Subject: Add a check to make sure schedulePass() has not deleted stale
 RequiredPass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139642 91177308-0d34-0410-b5e6-96231b3b80d8
---
 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 34f3768..ecedb1d 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
-- 
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