[SubZero] Implement Fcmp, ICmp, Cast and Select for vector type

src/IceTargetLowering.h

 //===- subzero/src/IceTargetLowering.h - Lowering interface -----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 493 matching lines @@
     assert(GeneratingTargetHelpers &&
            "scalarizeInstruction called during incorrect phase");
     const Type DestTy = Dest->getType();
     assert(isVectorType(DestTy));
     const Type DestElementTy = typeElementType(DestTy);
     const SizeT NumElements = typeNumElements(DestTy);
 
     Variable *T = Func->makeVariable(DestTy);
     if (auto *VarVecOn32 = llvm::dyn_cast<VariableVecOn32>(T)) {
       VarVecOn32->initVecElement(Func);
+      auto *Undef = ConstantUndef::create(Ctx, DestTy);
+      Context.insert<InstAssign>(T, Undef);
+    } else {
+      Context.insert<InstFakeDef>(T);
     }
-    Context.insert<InstFakeDef>(T);
 
     for (SizeT I = 0; I < NumElements; ++I) {
       auto *Index = Ctx->getConstantInt32(I);
 
       auto makeExtractThunk = [this, Index, NumElements](Operand *Src) {
         return [this, Index, NumElements, Src]() {
           assert(typeNumElements(Src->getType()) == NumElements);
 
           const auto ElementTy = typeElementType(Src->getType());
           auto *Op = Func->makeVariable(ElementTy);
@@ skipping 116 matching lines @@
   virtual void lower() {}
 
 protected:
   explicit TargetHeaderLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H