diff --git a/lib/CodeGen/ShrinkWrapping.cpp b/lib/CodeGen/ShrinkWrapping.cpp
index aeaa38b..7b5bca4 100644
--- a/lib/CodeGen/ShrinkWrapping.cpp
+++ b/lib/CodeGen/ShrinkWrapping.cpp
@@ -226,7 +226,7 @@
   // AnticIn[MBB] = UNION(CSRUsed[MBB], AnticOut[MBB]);
   CSRegSet prevAnticIn = AnticIn[MBB];
   AnticIn[MBB] = CSRUsed[MBB] | AnticOut[MBB];
-  if (prevAnticIn |= AnticIn[MBB])
+  if (prevAnticIn != AnticIn[MBB])
     changed = true;
   return changed;
 }
@@ -264,7 +264,7 @@
   // AvailOut[MBB] = UNION(CSRUsed[MBB], AvailIn[MBB]);
   CSRegSet prevAvailOut = AvailOut[MBB];
   AvailOut[MBB] = CSRUsed[MBB] | AvailIn[MBB];
-  if (prevAvailOut |= AvailOut[MBB])
+  if (prevAvailOut != AvailOut[MBB])
     changed = true;
   return changed;
 }