isl_basic_set_dim_residue_class: only set *modulo to 0 when dimension is fixed

[platform/upstream/isl.git] / isl_equalities.c

diff --git a/isl_equalities.c b/isl_equalities.c
index 1b517b6..cb16d17 100644 (file)
--- a/isl_equalities.c
+++ b/isl_equalities.c
@@ -550,6 +550,11 @@ error:
 /* Check if dimension dim belongs to a residue class
  *             i_dim \equiv r mod m
  * with m != 1 and if so return m in *modulo and r in *residue.
+ * As a special case, when i_dim has a fixed value v, then
+ * *modulo is set to 0 and *residue to v.
+ *
+ * If i_dim does not belong to such a residue class, then *modulo
+ * is set to 1 and *residue is set to 0.
  */
 int isl_basic_set_dim_residue_class(struct isl_basic_set *bset,
        int pos, isl_int *modulo, isl_int *residue)
@@ -562,6 +567,11 @@ int isl_basic_set_dim_residue_class(struct isl_basic_set *bset,
        if (!bset || !modulo || !residue)
                return -1;
 
+       if (isl_basic_set_fast_dim_is_fixed(bset, pos, residue)) {
+               isl_int_set_si(*modulo, 0);
+               return 0;
+       }
+
        ctx = bset->ctx;
        total = isl_basic_set_total_dim(bset);
        nparam = isl_basic_set_n_param(bset);
@@ -572,7 +582,9 @@ int isl_basic_set_dim_residue_class(struct isl_basic_set *bset,
 
        isl_seq_gcd(U->row[nparam + pos]+bset->n_eq,
                        total-bset->n_eq, modulo);
-       if (isl_int_is_zero(*modulo) || isl_int_is_one(*modulo)) {
+       if (isl_int_is_zero(*modulo))
+               isl_int_set_si(*modulo, 1);
+       if (isl_int_is_one(*modulo)) {
                isl_int_set_si(*residue, 0);
                isl_mat_free(H);
                isl_mat_free(U);
@@ -598,7 +610,7 @@ int isl_basic_set_dim_residue_class(struct isl_basic_set *bset,
                bset = isl_basic_set_copy(bset);
                bset = isl_basic_set_set_to_empty(bset);
                isl_basic_set_free(bset);
-               isl_int_set_si(*modulo, 0);
+               isl_int_set_si(*modulo, 1);
                isl_int_set_si(*residue, 0);
                return 0;
        }