Fix printing of debugging information in LiveIntervals::shrinkToUses

Print VNI->def before calling VNI->markUnused(), since markUnused makes
the def invalid.

llvm-svn: 275196
diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 1a8360b..5f3281f 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -564,9 +564,9 @@
       continue;
     if (VNI->isPHIDef()) {
       // This is a dead PHI. Remove it.
+      DEBUG(dbgs() << "Dead PHI at " << VNI->def << " may separate interval\n");
       VNI->markUnused();
       SR.removeSegment(*Segment);
-      DEBUG(dbgs() << "Dead PHI at " << VNI->def << " may separate interval\n");
     }
   }