Subzero: Add -Wshadow to the build.

src/IceTargetLoweringX86BaseImpl.h

Index: src/IceTargetLoweringX86BaseImpl.h
diff --git a/src/IceTargetLoweringX86BaseImpl.h b/src/IceTargetLoweringX86BaseImpl.h
index a277db23adc70e92847a998e9dd6ac8e9e1a6454..47fcf2755c807dd7a4af019ca245c049cd8abce2 100644
--- a/src/IceTargetLoweringX86BaseImpl.h
+++ b/src/IceTargetLoweringX86BaseImpl.h
@@ -26,7 +26,12 @@
 #include "IceLiveness.h"
 #include "IceOperand.h"
 #include "IceUtils.h"
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-parameter"
+#pragma clang diagnostic ignored "-Wshadow"
 #include "llvm/Support/MathExtras.h"
+#pragma clang diagnostic pop
 
 namespace Ice {
 namespace X86Internal {
@@ -193,10 +198,10 @@ void BoolFolding<MachineTraits>::init(CfgNode *Node) {
       Operand *Src = Instr.getSrc(I);
       SizeT NumVars = Src->getNumVars();
       for (SizeT J = 0; J < NumVars; ++J) {
-        const Variable *Var = Src->getVar(J);
-        SizeT VarNum = Var->getIndex();
+        const Variable *V = Src->getVar(J);
+        SizeT VarNum = V->getIndex();
         if (containsValid(VarNum)) {
-          if (I != 0 // All valid consumers use Var as the first source operand
+          if (I != 0 // All valid consumers use V as the first source operand
               || getConsumerKind(&Instr) == CK_None // must be white-listed
               || (Producers[VarNum].IsComplex && // complex can't be multi-use
                   Producers[VarNum].NumUses > 0)) {
@@ -204,7 +209,7 @@ void BoolFolding<MachineTraits>::init(CfgNode *Node) {
             continue;
           }
           ++Producers[VarNum].NumUses;
-          if (Instr.isLastUse(Var)) {
+          if (Instr.isLastUse(V)) {
             Producers[VarNum].IsLiveOut = false;
           }
         }
@@ -4705,9 +4710,9 @@ template <class Machine> void TargetX86Base<Machine>::prelowerPhis() {
       Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
       InstPhi *PhiLo = InstPhi::create(Func, Phi->getSrcSize(), DestLo);
       InstPhi *PhiHi = InstPhi::create(Func, Phi->getSrcSize(), DestHi);
-      for (SizeT I = 0; I < Phi->getSrcSize(); ++I) {
-        Operand *Src = Phi->getSrc(I);
-        CfgNode *Label = Phi->getLabel(I);
+      for (SizeT i = 0; i < Phi->getSrcSize(); ++i) {
+        Operand *Src = Phi->getSrc(i);
+        CfgNode *Label = Phi->getLabel(i);
         if (llvm::isa<ConstantUndef>(Src))
           Src = Ctx->getConstantZero(Dest->getType());
         PhiLo->addArgument(loOperand(Src), Label);