Index: lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
===================================================================
--- lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1813,6 +1813,20 @@
                                                   CI->getOperand(0), BaseValue);
   }
 
+  // PHI nodes that have the same incoming values, and belonging to the same
+  // basic blocks are essentially the same SSA value.
+  if (PHINode *PhiCurr = dyn_cast<PHINode>(CurrentValue))
+    if (PHINode *PhiBase = dyn_cast<PHINode>(BaseValue)) {
+      int phiNum = PhiCurr->getNumIncomingValues();
+      if (phiNum != PhiBase->getNumIncomingValues() ||
+          PhiCurr->getParent() != PhiBase->getParent())
+        return false;
+      for (unsigned i = 0; i < phiNum; i++)
+        if (PhiCurr->getIncomingValue(i) != PhiBase->getIncomingValue(i))
+          return false;
+      return true;
+    }
+
   // Not supported instruction in the chain
   return false;
 }