isl_basic_map_gauss: be careful not to introduce circular div definitions

diff --git a/isl_map_simplify.c b/isl_map_simplify.c
index b1f874e..4ffb507 100644 (file)
--- a/isl_map_simplify.c
+++ b/isl_map_simplify.c
@@ -395,8 +395,12 @@ static void eliminate_var_using_equality(struct isl_basic_map *bmap,
 {
        unsigned total;
        int k;
+       int contains_divs;
 
        total = isl_basic_map_total_dim(bmap);
+       contains_divs =
+               isl_seq_first_non_zero(eq + 1 + isl_dim_total(bmap->dim),
+                                               bmap->n_div) != -1;
        for (k = 0; k < bmap->n_eq; ++k) {
                if (bmap->eq[k] == eq)
                        continue;
@@ -423,8 +427,15 @@ static void eliminate_var_using_equality(struct isl_basic_map *bmap,
                        continue;
                if (progress)
                        *progress = 1;
-               isl_seq_elim(bmap->div[k]+1, eq,
-                               1+pos, 1+total, &bmap->div[k][0]);
+               /* We need to be careful about circular definitions,
+                * so for now we just remove the definition of div k
+                * if the equality contains any divs.
+                */
+               if (contains_divs)
+                       isl_seq_clr(bmap->div[k], 1 + total);
+               else
+                       isl_seq_elim(bmap->div[k]+1, eq,
+                                       1+pos, 1+total, &bmap->div[k][0]);
                F_CLR(bmap, ISL_BASIC_MAP_NORMALIZED);
        }
 }