Constify the key in Mi2IndexMap.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76801 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 261fa5e..ee07211 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -464,7 +464,7 @@
   i2miMap_.resize(highestSlot + 1);
   for (Mi2IndexMap::iterator MI = mi2iMap_.begin(), ME = mi2iMap_.end();
        MI != ME; ++MI) {
-    i2miMap_[MI->second] = MI->first;
+    i2miMap_[MI->second] = const_cast<MachineInstr *>(MI->first);
   }
 
 }