Now that we are deleting unused live intervals during allocation, poi…

…nters may be reused.

Use the virtual register number as a cache tag instead. They are not reused.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127561 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/LiveIntervalUnion.h

@@ -163,7 +163,7 @@ class LiveIntervalUnion {
     bool CheckedFirstInterference;
     bool SeenAllInterferences;
     bool SeenUnspillableVReg;
-    unsigned Tag;
+    unsigned Tag, VTag;
 
   public:
     Query(): LiveUnion(), VirtReg() {}
@@ -181,18 +181,20 @@ class LiveIntervalUnion {
       SeenAllInterferences = false;
       SeenUnspillableVReg = false;
       Tag = 0;
+      VTag = 0;
     }
 
     void init(LiveInterval *VReg, LiveIntervalUnion *LIU) {
       assert(VReg && LIU && "Invalid arguments");
-      if (VirtReg == VReg && LiveUnion == LIU && !LIU->changedSince(Tag)) {
+      if (VReg->reg == VTag && LiveUnion == LIU && !LIU->changedSince(Tag)) {
         // Retain cached results, e.g. firstInterference.
         return;
       }
       clear();
       LiveUnion = LIU;
       VirtReg = VReg;
       Tag = LIU->getTag();
+      VTag = VReg->reg;
     }
 
     LiveInterval &virtReg() const {