Fix PR9883. Make sure all caches are invalidated when a live range is repaired.

The previous invalidation missed the alias interference caches.

Also add a stats counter for the number of repaired ranges.

llvm-svn: 131133
diff --git a/llvm/lib/CodeGen/RegAllocBase.h b/llvm/lib/CodeGen/RegAllocBase.h
index f431d5a..b25ea23 100644
--- a/llvm/lib/CodeGen/RegAllocBase.h
+++ b/llvm/lib/CodeGen/RegAllocBase.h
@@ -113,6 +113,10 @@
     return Queries[PhysReg];
   }
 
+  // Invalidate all cached information about virtual registers - live ranges may
+  // have changed.
+  void invalidateVirtRegs() { ++UserTag; }
+
   // The top-level driver. The output is a VirtRegMap that us updated with
   // physical register assignments.
   //