Subzero: Dump register numbers as signed quantities.

src/IceRegAlloc.cpp

 //===- subzero/src/IceRegAlloc.cpp - Linear-scan implementation -----------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 53 matching lines @@
     Str << "," << Defs[i]->getNumber();
   }
   Str << "\n";
 }
 
 void dumpLiveRange(const Variable *Var, const Cfg *Func) {
   if (!BuildDefs::dump())
     return;
   Ostream &Str = Func->getContext()->getStrDump();
   char buf[30];
-  snprintf(buf, llvm::array_lengthof(buf), "%2u",
-           unsigned(Var->getRegNumTmp()));
+  snprintf(buf, llvm::array_lengthof(buf), "%2d",

[John, 2016/04/06 16:36:14]

What about printing None instead of -1?

[Jim Stichnoth, 2016/04/06 17:04:37]

I tried that, but then I realized that the whole snprintf plumbing is to try to
make the output line up nicely in columns.  Practically all register numbers
(including -1) fit within 2 chars.

I could do something else, maybe "xx" or "--"?  What do you think?  One think I
noticed is that "R=-1" and "R= 1" are a bit hard to distinguish in the output.

+           int32_t(Var->getRegNumTmp()));
   Str << "R=" << buf << "  V=";
   Var->dump(Func);
   Str << "  Range=" << Var->getLiveRange();
 }
 
 int32_t findMinWeightIndex(
     const SmallBitVector &RegMask,
     const llvm::SmallVector<RegWeight, LinearScan::REGS_SIZE> &Weights) {
   int MinWeightIndex = -1;
   for (RegNumT i : RegNumBVIter(RegMask)) {
@@ skipping 923 matching lines @@
     Str << "\n";
   }
   Str << "++++++ Inactive:\n";
   for (const Variable *Item : Inactive) {
     dumpLiveRange(Item, Func);
     Str << "\n";
   }
 }
 
 } // end of namespace Ice