[CodeGen] Use llvm::Type::getVectorNumElements instead of casting to llvm::VectorType and calling getNumElements. This is equivalent and shorter.

llvm-svn: 274823
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 50fbadf..3e1ae36 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -1758,8 +1758,7 @@
 
   if (const VectorType *VTy = Dst.getType()->getAs<VectorType>()) {
     unsigned NumSrcElts = VTy->getNumElements();
-    unsigned NumDstElts =
-       cast<llvm::VectorType>(Vec->getType())->getNumElements();
+    unsigned NumDstElts = Vec->getType()->getVectorNumElements();
     if (NumDstElts == NumSrcElts) {
       // Use shuffle vector is the src and destination are the same number of
       // elements and restore the vector mask since it is on the side it will be