Revert r135074 and r135080. They broke clamscan.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135096 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/InterferenceCache.h b/lib/CodeGen/InterferenceCache.h
index 6434b3a..6c36fa4 100644
--- a/lib/CodeGen/InterferenceCache.h
+++ b/lib/CodeGen/InterferenceCache.h
@@ -127,14 +127,10 @@
     Entry *CacheEntry;
     BlockInterference *Current;
   public:
-    /// Cursor - Create a dangling cursor.
-    Cursor() : CacheEntry(0), Current(0) {}
-
-    /// setPhysReg - Point this cursor to PhysReg's interference.
-    void setPhysReg(InterferenceCache &Cache, unsigned PhysReg) {
-      CacheEntry = Cache.get(PhysReg);
-      Current = 0;
-    }
+    /// Cursor - Create a cursor for the interference allocated to PhysReg and
+    /// all its aliases.
+    Cursor(InterferenceCache &Cache, unsigned PhysReg)
+      : CacheEntry(Cache.get(PhysReg)), Current(0) {}
 
     /// moveTo - Move cursor to basic block MBBNum.
     void moveToBlock(unsigned MBBNum) {