LIU:::Query: Query LiveRange instead of LiveInterval; NFC

- We only need the information from the base class, not the additional
  details in the LiveInterval class.
- Spread more `const`
- Some code cleanup

llvm-svn: 296684
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 01753ce..6ec0c82 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -698,7 +698,7 @@
     MCRegUnitIterator Units(PhysReg, TRI);
     for (; Units.isValid(); ++Units) {
       // Instantiate a "subquery", not to be confused with the Queries array.
-      LiveIntervalUnion::Query subQ(&VirtReg, &Matrix->getLiveUnions()[*Units]);
+      LiveIntervalUnion::Query subQ(VirtReg, Matrix->getLiveUnions()[*Units]);
       if (subQ.checkInterference())
         break;
     }