Subzero: Ignore variables with no actual uses.

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 201 matching lines @@
   // Iterate across all instructions and record the begin and end of the live
   // range for each variable that is pre-colored or infinite weight.
   CfgVector<InstNumberT> LRBegin(Vars.size(), Inst::NumberSentinel);
   CfgVector<InstNumberT> LREnd(Vars.size(), Inst::NumberSentinel);
   DefUseErrorList DefsWithoutUses, UsesBeforeDefs;
   for (CfgNode *Node : Func->getNodes()) {
     for (Inst &Instr : Node->getInsts()) {
       if (Instr.isDeleted())
         continue;
       FOREACH_VAR_IN_INST(Var, Instr) {
-        if (Var->isRematerializable())
-          continue;
         if (Var->getIgnoreLiveness())
           continue;
         if (Var->hasReg() || Var->mustHaveReg()) {
           SizeT VarNum = Var->getIndex();
           LREnd[VarNum] = Instr.getNumber();
           if (!Var->getIsArg() && LRBegin[VarNum] == Inst::NumberSentinel)
             UsesBeforeDefs.push_back(VarNum);
         }
       }
       if (const Variable *Var = Instr.getDest()) {
-        if (!Var->isRematerializable() && !Var->getIgnoreLiveness() &&
+        if (!Var->getIgnoreLiveness() &&
             (Var->hasReg() || Var->mustHaveReg())) {
           if (LRBegin[Var->getIndex()] == Inst::NumberSentinel) {
             LRBegin[Var->getIndex()] = Instr.getNumber();
             ++NumVars;
           }
         }
       }
     }
   }
 
@@ skipping 766 matching lines @@
     Str << "\n";
   }
   Str << "++++++ Inactive:\n";
   for (const Variable *Item : Inactive) {
     dumpLiveRange(Item, Func);
     Str << "\n";
   }
 }
 
 } // end of namespace Ice