add test for root equality

Author: j2kun

mlir/test/Dialect/Polynomial/canonicalization.mlir

@@ -101,3 +101,17 @@ func.func @test_canonicalize_fold_sub_through_intt(
   %out = polynomial.ntt %a_plus_b {root=#root} : !ntt_poly_ty -> !tensor_ty
   return %out : !tensor_ty
 }
+
+
+// CHECK-LABEL: test_canonicalize_do_not_fold_different_roots
+// CHECK: arith.addi
+func.func @test_canonicalize_do_not_fold_different_roots(
+    %poly0 : !ntt_poly_ty,
+    %poly1 : !ntt_poly_ty) -> !ntt_poly_ty {
+  %0 = polynomial.ntt %poly0 {root=#polynomial.primitive_root<value=31:i32, degree=8:index>} : !ntt_poly_ty -> !tensor_ty
+  %1 = polynomial.ntt %poly1 {root=#polynomial.primitive_root<value=33:i32, degree=8:index>} : !ntt_poly_ty -> !tensor_ty
+  %a_plus_b = arith.addi %0, %1 : !tensor_ty
+  %out = polynomial.intt %a_plus_b {root=#root} : !tensor_ty -> !ntt_poly_ty
+  return %out : !ntt_poly_ty
+}
+