Don't worry about clobbering physical register defs that aren't used.

llvm-svn: 56281
diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index b9dcc25..0cf155e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -1709,6 +1709,8 @@
     MVT VT = N->getValueType(i);
     if (VT == MVT::Flag || VT == MVT::Other)
       continue;
+    if (!N->hasAnyUseOfValue(i))
+      continue;
     unsigned Reg = ImpDefs[i - NumDefs];
     for (;*SUImpDefs; ++SUImpDefs) {
       unsigned SUReg = *SUImpDefs;