add vector descriptor helper

Author: yhmtsai

include/spblas/vendor/rocsparse/descriptor.hpp

@@ -29,5 +29,17 @@ rocsparse_spmat_descr create_matrix_descr(mat&& a) {
   return descr;
 }
 
+// create dense vector from mdspan
+template <vector vec>
+  requires __ranges::contiguous_range<vec>
+rocsparse_dnvec_descr create_vector_descr(vec&& v) {
+  using vector_type = std::remove_cvref_t<vec>;
+  rocsparse_dnvec_descr descr;
+  throw_if_error(rocsparse_create_dnvec_descr(
+      &descr, v.size(), v.data(),
+      to_rocsparse_datatype<typename vector_type::value_type>()));
+  return descr;
+}
+
 } // namespace __rocsparse
 } // namespace spblas

include/spblas/vendor/rocsparse/multiply.hpp

@@ -61,14 +61,8 @@ class spmv_state_t {
     auto handle = this->handle_.get();
 
     rocsparse_spmat_descr mat = __rocsparse::create_matrix_descr(a_base);
-    rocsparse_dnvec_descr vecb;
-    rocsparse_dnvec_descr vecc;
-    __rocsparse::throw_if_error(rocsparse_create_dnvec_descr(
-        &vecb, b_base.size(), b_base.data(),
-        to_rocsparse_datatype<typename input_type::value_type>()));
-    __rocsparse::throw_if_error(rocsparse_create_dnvec_descr(
-        &vecc, c.size(), c.data(),
-        to_rocsparse_datatype<typename output_type::value_type>()));
+    rocsparse_dnvec_descr vecb = __rocsparse::create_vector_descr(b_base);
+    rocsparse_dnvec_descr vecc = __rocsparse::create_vector_descr(c);
     value_type alpha_val = alpha;
     value_type beta = 0.0;
     long unsigned int buffer_size = 0;