Privatize an unused part of the LiveIntervalUnion::Query interface.

No clients are iterating over interference overlaps.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137350 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocBasic.cpp b/lib/CodeGen/RegAllocBasic.cpp
index a97b9b6..5496d69 100644
--- a/lib/CodeGen/RegAllocBasic.cpp
+++ b/lib/CodeGen/RegAllocBasic.cpp
@@ -498,8 +498,9 @@
       // Found an available register.
       return PhysReg;
     }
+    Queries[interfReg].collectInterferingVRegs(1);
     LiveInterval *interferingVirtReg =
-      Queries[interfReg].firstInterference().liveUnionPos().value();
+      Queries[interfReg].interferingVRegs().front();
 
     // The current VirtReg must either be spillable, or one of its interferences
     // must have less spill weight.