[SVE] Remove invalid usage of getNumElements in Instructions

[ctetreau]

Summary

Remove invalid usage of VectorType::getNumElements in
ShuffleVectorInst::isValidOperands identified by test case
llvm::Analysis/ConstantFolding/vscale-shufflevector.ll. The tested
conditions hold for both fixed width and scalable vectors; use
getElementCount().

[sdesmalen]

LGTM

llvm/lib/IR/Instructions.cpp

void ShuffleVectorInst::commute() {
   }
   setShuffleMask(NewMask);
   Op<0>().swap(Op<1>());
 }
 
 bool ShuffleVectorInst::isValidOperands(const Value *V1, const Value *V2,
                                         ArrayRef<int> Mask) {
   // V1 and V2 must be vectors of the same type.
-  if (!V1->getType()->isVectorTy() || V1->getType() != V2->getType())
+  if (!isa<VectorType>(V1->getType()) || V1->getType() != V2->getType())
     return false;
 
   // Make sure the mask elements make sense.
-  int V1Size = cast<VectorType>(V1->getType())->getNumElements();
+  int V1Size = cast<VectorType>(V1->getType())->getElementCount().Min;
   for (int Elem : Mask)
     if (Elem != UndefMaskElem && Elem >= V1Size * 2)
       return false;
 
   if (isa<ScalableVectorType>(V1->getType()))
     if ((Mask[0] != 0 && Mask[0] != UndefMaskElem) || !is_splat(Mask))
       return false;