+ if (VectorType *VecTy = dyn_cast<VectorType>(SI.getType())) {
+ unsigned VWidth = VecTy->getNumElements();
+ APInt UndefElts(VWidth, 0);
+ APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
+ if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
+ if (V != &SI)
+ return ReplaceInstUsesWith(SI, V);
+ return &SI;
+ }
+
+ if (ConstantVector *CV = dyn_cast<ConstantVector>(CondVal)) {
+ // Form a shufflevector instruction.
+ SmallVector<Constant *, 8> Mask(VWidth);
+ Type *Int32Ty = Type::getInt32Ty(CV->getContext());
+ for (unsigned i = 0; i != VWidth; ++i) {
+ Constant *Elem = cast<Constant>(CV->getOperand(i));
+ if (ConstantInt *E = dyn_cast<ConstantInt>(Elem))
+ Mask[i] = ConstantInt::get(Int32Ty, i + (E->isZero() ? VWidth : 0));
+ else if (isa<UndefValue>(Elem))
+ Mask[i] = UndefValue::get(Int32Ty);
+ else
+ return 0;
+ }
+ Constant *MaskVal = ConstantVector::get(Mask);
+ Value *V = Builder->CreateShuffleVector(TrueVal, FalseVal, MaskVal);
+ return ReplaceInstUsesWith(SI, V);
+ }
+
+ if (isa<ConstantAggregateZero>(CondVal)) {
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+ }
+