// CHECK-DAG: %[[ZERO_MAT:.*]] = "mhlo.broadcast"(%[[ZERO]]) <{broadcast_sizes = dense<12> : tensor<2xi64>}> : (tensor<f32>) -> tensor<12x12xf32>
  // CHECK-DAG: %[[SEL:.*]] = mhlo.select %[[COMP]], %[[RS]], %[[ZERO_MAT]] : tensor<12x12xi1>, tensor<12x12xf32>
  // CHECK-DAG: %[[RED:.*]] = mhlo.reduce(%[[SEL]] init: %[[ZERO]]) applies mhlo.add across dimensions = [0] : (tensor<12x12xf32>, tensor<f32>) -> tensor<12xf32>

func fieldIdx(n *ir.SelectorExpr) int {
	t := n.X.Type()
	if !t.IsStruct() {
		panic("ODOT's LHS is not a struct")
	}

	for i, f := range t.Fields() {
		if f.Sym == n.Sel {
			if f.Offset != n.Offset() {
				panic("field offset doesn't match")
			}
			return i
		}
	}
	panic(fmt.Sprintf("can't find field in expr %v\n", n))