Subzero: Use "auto" per (unwritten) auto coding style.

src/IceInst.cpp

 //===- subzero/src/IceInst.cpp - High-level instruction implementation ----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 76 matching lines @@
 void Inst::deleteIfDead() {
   if (Dead)
     setDeleted();
 }
 
 // If Src is a Variable, it returns true if this instruction ends Src's live
 // range. Otherwise, returns false.
 bool Inst::isLastUse(const Operand *TestSrc) const {
   if (LiveRangesEnded == 0)
     return false; // early-exit optimization
-  if (const Variable *TestVar = llvm::dyn_cast<const Variable>(TestSrc)) {
+  if (auto *TestVar = llvm::dyn_cast<const Variable>(TestSrc)) {
     LREndedBits Mask = LiveRangesEnded;
     FOREACH_VAR_IN_INST(Var, *this) {
       if (Var == TestVar) {
         // We've found where the variable is used in the instruction.
         return Mask & 1;
       }
       Mask >>= 1;
       if (Mask == 0)
         return false; // another early-exit optimization
     }
@@ skipping 251 matching lines @@
 
 // Updates liveness for a particular operand based on the given predecessor
 // edge. Doesn't mark the operand as live if the Phi instruction is dead or
 // deleted.
 void InstPhi::livenessPhiOperand(LivenessBV &Live, CfgNode *Target,
                                  Liveness *Liveness) {
   if (isDeleted() || Dead)
     return;
   for (SizeT I = 0; I < getSrcSize(); ++I) {
     if (Labels[I] == Target) {
-      if (Variable *Var = llvm::dyn_cast<Variable>(getSrc(I))) {
+      if (auto *Var = llvm::dyn_cast<Variable>(getSrc(I))) {
         SizeT SrcIndex = Liveness->getLiveIndex(Var->getIndex());
         if (!Live[SrcIndex]) {
           setLastUse(I);
           Live[SrcIndex] = true;
         }
       }
       return;
     }
   }
   llvm_unreachable("Phi operand not found for specified target node");
@@ skipping 578 matching lines @@
     // upper 32 bits of rax. We need to recognize and preserve these.
     return true;
   }
   if (!Dest->hasReg() && !SrcVar->hasReg() &&
       Dest->getStackOffset() == SrcVar->getStackOffset())
     return true;
   return false;
 }
 
 } // end of namespace Ice