1 files changed, 7 insertions, 2 deletions
diff --git a/lib/CodeGen/RegAllocBase.h b/lib/CodeGen/RegAllocBase.h
index 5af0ce79acf7..f431d5a5a026 100644
--- a/lib/CodeGen/RegAllocBase.h
+++ b/lib/CodeGen/RegAllocBase.h
@@ -61,6 +61,11 @@ class LiveVirtRegQueue;
 /// assignment order.
 class RegAllocBase {
   LiveIntervalUnion::Allocator UnionAllocator;
+
+  // Cache tag for PhysReg2LiveUnion entries. Increment whenever virtual
+  // registers may have changed.
+  unsigned UserTag;
+
 protected:
   // Array of LiveIntervalUnions indexed by physical register.
   class LiveUnionArray {
@@ -92,7 +97,7 @@ protected:
   // query on a new live virtual register.
   OwningArrayPtr<LiveIntervalUnion::Query> Queries;
 
-  RegAllocBase(): TRI(0), MRI(0), VRM(0), LIS(0) {}
+  RegAllocBase(): UserTag(0), TRI(0), MRI(0), VRM(0), LIS(0) {}
 
   virtual ~RegAllocBase() {}
 
@@ -104,7 +109,7 @@ protected:
   // before querying a new live virtual register. This ties Queries and
   // PhysReg2LiveUnion together.
   LiveIntervalUnion::Query &query(LiveInterval &VirtReg, unsigned PhysReg) {
-    Queries[PhysReg].init(&VirtReg, &PhysReg2LiveUnion[PhysReg]);
+    Queries[PhysReg].init(UserTag, &VirtReg, &PhysReg2LiveUnion[PhysReg]);
     return Queries[PhysReg];
   }