Subzero: Improve non-MINIMAL string performance.

src/IceCfgNode.h

 //===- subzero/src/IceCfgNode.h - Control flow graph node -------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 19 matching lines @@
 public:
   static CfgNode *create(Cfg *Func, SizeT Number) {
     return new (Func->allocate<CfgNode>()) CfgNode(Func, Number);
   }
 
   Cfg *getCfg() const { return Func; }
 
   /// Access the label number and name for this node.
   SizeT getIndex() const { return Number; }
   void resetIndex(SizeT NewNumber) { Number = NewNumber; }
-  NodeString getName() const { return Name; }
+  std::string getName() const {
+    if (Name.hasStdString())
+      return Name.toString();
+    return "__" + std::to_string(NumberOrig);
+  }
   void setName(const std::string &NewName) {
     if (NewName.empty())
       return;
     Name = NodeString::createWithString(Func, NewName);
   }
   std::string getAsmName() const {
     return ".L" + Func->getFunctionName() + "$" + getName();
   }
 
   void incrementLoopNestDepth() { ++LoopNestDepth; }
@@ skipping 60 matching lines @@
   void profileExecutionCount(VariableDeclaration *Var);
 
   void addOutEdge(CfgNode *Out) { OutEdges.push_back(Out); }
   void addInEdge(CfgNode *In) { InEdges.push_back(In); }
 
   bool hasSingleOutEdge() const {
     return (getOutEdges().size() == 1 || getOutEdges()[0] == getOutEdges()[1]);
   }
 
 private:
-  CfgNode(Cfg *Func, SizeT Number);
+  CfgNode(Cfg *Func, SizeT Number)
+      : Func(Func), Number(Number), NumberOrig(Number),
+        Name(NodeString::createWithoutString(Func)) {}
   bool livenessValidateIntervals(Liveness *Liveness) const;
   Cfg *const Func;
-  SizeT Number; /// invariant: Func->Nodes[Number]==this
+  SizeT Number;           /// invariant: Func->Nodes[Number]==this
+  const SizeT NumberOrig; /// used for name auto-generation
   NodeString Name;
   SizeT LoopNestDepth = 0; /// the loop nest depth of this node
   bool HasReturn = false;  /// does this block need an epilog?
   bool NeedsPlacement = false;
   bool NeedsAlignment = false;       /// is sandboxing required?
   InstNumberT InstCountEstimate = 0; /// rough instruction count estimate
   NodeList InEdges;                  /// in no particular order
   NodeList OutEdges;                 /// in no particular order
   PhiList Phis;                      /// unordered set of phi instructions
   InstList Insts;                    /// ordered list of non-phi instructions
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICECFGNODE_H