Compute the loop nest depth of each CfgNode and weight Variables by it.

src/IceCfg.h

 //===- subzero/src/IceCfg.h - Control flow graph ----------------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 68 matching lines @@
   /// translator handle the function.
   void setError(const IceString &Message);
   bool hasError() const { return HasError; }
   IceString getError() const { return ErrorMessage; }
   /// @}
 
   /// \name Manage nodes (a.k.a. basic blocks, CfgNodes).
   /// @{
   void setEntryNode(CfgNode *EntryNode) { Entry = EntryNode; }
   CfgNode *getEntryNode() const { return Entry; }
-  /// Create a node and append it to the end of the linearized list.
+  /// Create a node and append it to the end of the linearized list. The loop
+  /// nest depth of the new node may not be valid if it is created after
+  /// computeLoopNestDepth.
   CfgNode *makeNode();
   SizeT getNumNodes() const { return Nodes.size(); }
   const NodeList &getNodes() const { return Nodes; }
   /// Swap nodes of Cfg with given list of nodes.
   void swapNodes(NodeList &NewNodes);
   /// @}
 
   typedef int32_t IdentifierIndexType;
   /// Adds a name to the list and returns its index, suitable for the
   /// argument to getIdentifierName().  No checking for duplicates is
@@ skipping 82 matching lines @@
   void placePhiStores();
   void deletePhis();
   void advancedPhiLowering();
   void reorderNodes();
   void shuffleNodes();
   void doAddressOpt();
   void doArgLowering();
   void doNopInsertion();
   void genCode();
   void genFrame();
+  void computeLoopNestDepth();
   void livenessLightweight();
   void liveness(LivenessMode Mode);
   bool validateLiveness() const;
   void contractEmptyNodes();
   void doBranchOpt();
   void markNodesForSandboxing();
 
   /// \name  Manage the CurrentNode field.
   /// CurrentNode is used for validating the Variable::DefNode field during
   /// dumping/emitting.
@@ skipping 83 matching lines @@
   /// other uses are possible.
   ICE_TLS_DECLARE_FIELD(const Cfg *, CurrentCfg);
 
 public:
   static void TlsInit() { ICE_TLS_INIT_FIELD(CurrentCfg); }
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICECFG_H