Subzero: Fix a bug in register allocator overlap computation.

src/IceCfg.cpp

 //===- subzero/src/IceCfg.cpp - Control flow graph implementation ---------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 784 matching lines @@
   }
   resetCurrentNode();
   if (isVerbose(IceV_Liveness)) {
     // Print summary info about variables
     for (Variable *Var : Variables) {
       Str << "// multiblock=";
       if (getVMetadata()->isTracked(Var))
         Str << getVMetadata()->isMultiBlock(Var);
       else
         Str << "?";
+      Str << " defs=";
+      bool FirstPrint = true;
+      if (VMetadata->getKind() != VMK_Uses) {
+        if (const Inst *FirstDef = VMetadata->getFirstDefinition(Var)) {
+          Str << FirstDef->getNumber();
+          FirstPrint = false;
+        }
+      }
+      if (VMetadata->getKind() == VMK_All) {
+        for (const Inst *Instr : VMetadata->getLatterDefinitions(Var)) {
+          if (!FirstPrint)
+            Str << ",";
+          Str << Instr->getNumber();
+          FirstPrint = false;
+        }
+      }
       Str << " weight=" << Var->getWeight(this) << " ";
       Var->dump(this);
       Str << " LIVE=" << Var->getLiveRange() << "\n";
     }
   }
   // Print each basic block
   for (CfgNode *Node : Nodes)
     Node->dump(this);
   if (isVerbose(IceV_Instructions))
     Str << "}\n";
 }
 
 } // end of namespace Ice