isl_map_simplify.c: remove_duplicate_divs: remove divs from last to first

diff --git a/isl_map_simplify.c b/isl_map_simplify.c
index 4ffb507..d1c23d2 100644 (file)
--- a/isl_map_simplify.c
+++ b/isl_map_simplify.c
@@ -533,11 +533,17 @@ static int set_hash_index(isl_int ***index, unsigned int size, int bits,
        return hash_index(index, size, bits, (struct isl_basic_map *)bset, k);
 }
 
+/* If we can eliminate more than one div, then we need to make
+ * sure we do it from last div to first div, in order not to
+ * change the position of the other divs that still need to
+ * be removed.
+ */
 static struct isl_basic_map *remove_duplicate_divs(
        struct isl_basic_map *bmap, int *progress)
 {
        unsigned int size;
        int *index;
+       int *elim_for;
        int k, l, h;
        int bits;
        struct isl_blk eq;
@@ -555,6 +561,7 @@ static struct isl_basic_map *remove_duplicate_divs(
        if (k <= 0)
                return bmap;
 
+       elim_for = isl_calloc_array(ctx, int, bmap->n_div);
        size = round_up(4 * bmap->n_div / 3 - 1);
        bits = ffs(size) - 1;
        index = isl_calloc_array(ctx, int, size);
@@ -580,18 +587,25 @@ static struct isl_basic_map *remove_duplicate_divs(
                if (index[h]) {
                        *progress = 1;
                        l = index[h] - 1;
-                       isl_int_set_si(eq.data[1+total_var+k], -1);
-                       isl_int_set_si(eq.data[1+total_var+l], 1);
-                       eliminate_div(bmap, eq.data, l);
-                       isl_int_set_si(eq.data[1+total_var+k], 0);
-                       isl_int_set_si(eq.data[1+total_var+l], 0);
+                       elim_for[l] = k + 1;
                }
                index[h] = k+1;
        }
+       for (l = bmap->n_div - 1; l >= 0; --l) {
+               if (!elim_for[l])
+                       continue;
+               k = elim_for[l] - 1;
+               isl_int_set_si(eq.data[1+total_var+k], -1);
+               isl_int_set_si(eq.data[1+total_var+l], 1);
+               eliminate_div(bmap, eq.data, l);
+               isl_int_set_si(eq.data[1+total_var+k], 0);
+               isl_int_set_si(eq.data[1+total_var+l], 0);
+       }
 
        isl_blk_free(ctx, eq);
 out:
        free(index);
+       free(elim_for);
        return bmap;
 }