+
+/* Compute the preimage of "ls" under the function represented by "ma".
+ * In other words, plug in "ma" in "ls". The result is a local space
+ * that is part of the domain space of "ma".
+ *
+ * If the divs in "ls" are represented as
+ *
+ * floor((a_i(p) + b_i x + c_i(divs))/n_i)
+ *
+ * and ma is represented by
+ *
+ * x = D(p) + F(y) + G(divs')
+ *
+ * then the resulting divs are
+ *
+ * floor((a_i(p) + b_i D(p) + b_i F(y) + B_i G(divs') + c_i(divs))/n_i)
+ *
+ * We first copy over the divs from "ma" and then
+ * we add the modified divs from "ls".
+ */
+__isl_give isl_local_space *isl_local_space_preimage_multi_aff(
+ __isl_take isl_local_space *ls, __isl_take isl_multi_aff *ma)
+{
+ int i;
+ isl_space *space;
+ isl_local_space *res = NULL;
+ int n_div_ls, n_div_ma;
+ isl_int f, c1, c2, g;
+
+ ma = isl_multi_aff_align_divs(ma);
+ if (!ls || !ma)
+ goto error;
+ if (!isl_space_is_range_internal(ls->dim, ma->space))
+ isl_die(isl_local_space_get_ctx(ls), isl_error_invalid,
+ "spaces don't match", goto error);
+
+ n_div_ls = isl_local_space_dim(ls, isl_dim_div);
+ n_div_ma = ma->n ? isl_aff_dim(ma->p[0], isl_dim_div) : 0;
+
+ space = isl_space_domain(isl_multi_aff_get_space(ma));
+ res = isl_local_space_alloc(space, n_div_ma + n_div_ls);
+ if (!res)
+ goto error;
+
+ if (n_div_ma) {
+ isl_mat_free(res->div);
+ res->div = isl_mat_copy(ma->p[0]->ls->div);
+ res->div = isl_mat_add_zero_cols(res->div, n_div_ls);
+ res->div = isl_mat_add_rows(res->div, n_div_ls);
+ if (!res->div)
+ goto error;
+ }
+
+ isl_int_init(f);
+ isl_int_init(c1);
+ isl_int_init(c2);
+ isl_int_init(g);
+
+ for (i = 0; i < ls->div->n_row; ++i) {
+ if (isl_int_is_zero(ls->div->row[i][0])) {
+ isl_int_set_si(res->div->row[n_div_ma + i][0], 0);
+ continue;
+ }
+ isl_seq_preimage(res->div->row[n_div_ma + i], ls->div->row[i],
+ ma, 0, 0, n_div_ma, n_div_ls, f, c1, c2, g, 1);
+ normalize_div(res, n_div_ma + i);
+ }
+
+ isl_int_clear(f);
+ isl_int_clear(c1);
+ isl_int_clear(c2);
+ isl_int_clear(g);
+
+ isl_local_space_free(ls);
+ isl_multi_aff_free(ma);
+ return res;
+error:
+ isl_local_space_free(ls);
+ isl_multi_aff_free(ma);
+ isl_local_space_free(res);
+ return NULL;
+}