Dead code elimination may separate the live interval into multiple connected components.

I have convinced myself that it can only happen when a phi value dies. When it
happens, allocate new virtual registers for the components.

llvm-svn: 127827

1 files changed, 8 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/LiveRangeEdit.h b/llvm/lib/CodeGen/LiveRangeEdit.h
index 2bd34611c24..0846961f5b9 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.h
+++ b/llvm/lib/CodeGen/LiveRangeEdit.h
@@ -65,6 +65,9 @@ private:
   /// live range trimmed or entirely removed.
   SmallPtrSet<const VNInfo*,4> rematted_;
 
+  /// createFrom - Create a new virtual register based on OldReg.
+  LiveInterval &createFrom(unsigned, LiveIntervals&, VirtRegMap &);
+
   /// scanRemattable - Identify the parent_ values that may rematerialize.
   void scanRemattable(LiveIntervals &lis,
                       const TargetInstrInfo &tii,
@@ -110,9 +113,11 @@ public:
     return uselessRegs_;
   }
 
-  /// create - Create a new register with the same class and stack slot as
+  /// create - Create a new register with the same class and original slot as
   /// parent.
-  LiveInterval &create(MachineRegisterInfo&, LiveIntervals&, VirtRegMap&);
+  LiveInterval &create(LiveIntervals &LIS, VirtRegMap &VRM) {
+    return createFrom(getReg(), LIS, VRM);
+  }
 
   /// anyRematerializable - Return true if any parent values may be
   /// rematerializable.
@@ -166,7 +171,7 @@ public:
   /// (allDefsAreDead returns true). This may cause live intervals to be trimmed
   /// and further dead efs to be eliminated.
   void eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
-                         LiveIntervals&,
+                         LiveIntervals&, VirtRegMap&,
                          const TargetInstrInfo&);
 
 };