Subzero: Cleanly implement register allocation after phi lowering.

src/IceLiveness.h

Index: src/IceLiveness.h
diff --git a/src/IceLiveness.h b/src/IceLiveness.h
index 7fcad253a8d04618f3a9d5f3076747179d90952b..da2c52ea47142543a778fed88308c366fa0f8408 100644
--- a/src/IceLiveness.h
+++ b/src/IceLiveness.h
@@ -63,6 +63,8 @@ class Liveness {
 public:
   Liveness(Cfg *Func, LivenessMode Mode) : Func(Func), Mode(Mode) {}
   void init();
+  void initPhiEdgeSplits(NodeList::const_iterator FirstNode,
+                         VarList::const_iterator FirstVar);
   Cfg *getFunc() const { return Func; }
   LivenessMode getMode() const { return Mode; }
   Variable *getVariable(SizeT LiveIndex, const CfgNode *Node) const;
@@ -96,6 +98,8 @@ public:
   }
 
 private:
+  void initInternal(NodeList::const_iterator FirstNode,
+                    VarList::const_iterator FirstVar, bool IsFullInit);
   /// Resize Nodes so that Nodes[Index] is valid.
   void resize(SizeT Index) {
     if (Index >= Nodes.size())