MemRef type in interface

It is a follow-up to #44, and maybe I've asked about this earlier: could we generate function interface that has MemRef types with explicit dimensionality? For example, take the code from #44:

module attributes {llvm.data_layout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128", llvm.target_triple = "x86_64-unknown-linux-gnu"}  {
  func @matmul(%arg0: memref<?x400xf32>, %arg1: memref<?x300xf32>, %arg2: memref<?x300xf32>) {
    affine.for %arg3 = 0 to 200 {
      affine.for %arg4 = 0 to 300 {
        affine.for %arg5 = 0 to 400 {
          %0 = affine.load %arg0[%arg3, %arg5] : memref<?x400xf32>
          %1 = affine.load %arg1[%arg5, %arg4] : memref<?x300xf32>
          %2 = mulf %0, %1 : f32
          %3 = affine.load %arg2[%arg3, %arg4] : memref<?x300xf32>
          %4 = addf %3, %2 : f32
          affine.store %4, %arg2[%arg3, %arg4] : memref<?x300xf32>
        }
      }
    }
    return
  }
}

How could we make the interface of @matmul to be:

func @matmul(%arg0: memref<200x400xf32>, %arg1: memref<400x300xf32>, %arg2: memref<200x300xf32>)

Thanks!