Subzero: Cleanly implement register allocation after phi lowering.

src/IceLiveness.h

 //===- subzero/src/IceLiveness.h - Liveness analysis ------------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 45 matching lines @@
     // LiveBegin and LiveEnd track the instruction numbers of the start
     // and end of each variable's live range within this block.  The
     // index/key of each element is less than NumLocals +
     // Liveness::NumGlobals.
     LiveBeginEndMap LiveBegin, LiveEnd;
   };
 
 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;
   SizeT getLiveIndex(SizeT VarIndex) const { return VarToLiveMap[VarIndex]; }
   SizeT getNumGlobalVars() const { return NumGlobals; }
   SizeT getNumVarsInNode(const CfgNode *Node) const {
     return NumGlobals + Nodes[Node->getIndex()].NumLocals;
   }
   SizeT &getNumNonDeadPhis(const CfgNode *Node) {
     return Nodes[Node->getIndex()].NumNonDeadPhis;
@@ skipping 13 matching lines @@
     resize(Index);
     return &Nodes[Index].LiveBegin;
   }
   LiveBeginEndMap *getLiveEnd(const CfgNode *Node) {
     SizeT Index = Node->getIndex();
     resize(Index);
     return &Nodes[Index].LiveEnd;
   }
 
 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())
       Nodes.resize(Index + 1);
   }
   Cfg *Func;
   LivenessMode Mode;
   SizeT NumGlobals = 0;
   /// Size of Nodes is Cfg::Nodes.size().
   std::vector<LivenessNode> Nodes;
   /// VarToLiveMap maps a Variable's Variable::Number to its live index
   /// within its basic block.
   std::vector<SizeT> VarToLiveMap;
   /// LiveToVarMap is analogous to LivenessNode::LiveToVarMap, but for
   /// non-local variables.
   std::vector<Variable *> LiveToVarMap;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICELIVENESS_H