Subzero: Improve debugging controls, plus minor refactoring.

src/IceOperand.cpp

 //===- subzero/src/IceOperand.cpp - High-level operand implementation -----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the Operand class and its target-independent
@@ skipping 153 matching lines @@
 }
 
 void LiveRange::trim(InstNumberT Lower) {
   while (TrimmedBegin != Range.end() && TrimmedBegin->second <= Lower)
     ++TrimmedBegin;
 }
 
 IceString Variable::getName() const {
   if (!Name.empty())
     return Name;
-  char buf[30];
-  snprintf(buf, llvm::array_lengthof(buf), "__%u", getIndex());
-  return buf;
+  return "__" + std::to_string(getIndex());
 }
 
 Variable Variable::asType(Type Ty) {
   // Note: This returns a Variable, even if the "this" object is a
   // subclass of Variable.
   Variable V(kVariable, Ty, Number, Name);
   V.RegNum = RegNum;
   V.StackOffset = StackOffset;
   return V;
 }
@@ skipping 302 matching lines @@
 
 Ostream &operator<<(Ostream &Str, const RegWeight &W) {
   if (W.getWeight() == RegWeight::Inf)
     Str << "Inf";
   else
     Str << W.getWeight();
   return Str;
 }
 
 } // end of namespace Ice