From c56d8f90fd2afe302a2bade752b9b97a4d8a90e4 Mon Sep 17 00:00:00 2001
From: Hal Finkel <hfinkel@anl.gov>
Date: Thu, 12 Sep 2013 04:22:31 +0000
Subject: [PATCH] Fix crash in AggressiveAntiDepBreaker with empty
 CriticalPathSet

If no register classes are added to CriticalPathRCs, then the CriticalPathSet
bitmask will be empty. In that case, ExcludeRegs must remain NULL or else this
line will cause a segfault:

  } else if ((ExcludeRegs != NULL) && ExcludeRegs->test(AntiDepReg)) {

I have no in-tree test case.

llvm-svn: 190584
---
 lib/CodeGen/AggressiveAntiDepBreaker.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/CodeGen/AggressiveAntiDepBreaker.cpp b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
index e0797079c5e..2ee77671158 100644
--- a/lib/CodeGen/AggressiveAntiDepBreaker.cpp
+++ b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
@@ -782,7 +782,7 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
     if (MI == CriticalPathMI) {
       CriticalPathSU = CriticalPathStep(CriticalPathSU);
       CriticalPathMI = (CriticalPathSU) ? CriticalPathSU->getInstr() : 0;
-    } else {
+    } else if (CriticalPathSet.any()) {
       ExcludeRegs = &CriticalPathSet;
     }