return 1;
}
+/* Would an expression for div "div" based on inequality "ineq" of "bmap"
+ * be a better expression than the current one?
+ *
+ * If we do not have any expression yet, then any expression would be better.
+ * Otherwise we check if the last variable involved in the inequality
+ * (disregarding the div that it would define) is in an earlier position
+ * than the last variable involved in the current div expression.
+ */
+static int better_div_constraint(__isl_keep isl_basic_map *bmap,
+ int div, int ineq)
+{
+ unsigned total = 1 + isl_space_dim(bmap->dim, isl_dim_all);
+ int last_div;
+ int last_ineq;
+
+ if (isl_int_is_zero(bmap->div[div][0]))
+ return 1;
+
+ if (isl_seq_last_non_zero(bmap->ineq[ineq] + total + div + 1,
+ bmap->n_div - (div + 1)) >= 0)
+ return 0;
+
+ last_ineq = isl_seq_last_non_zero(bmap->ineq[ineq], total + div);
+ last_div = isl_seq_last_non_zero(bmap->div[div] + 1,
+ total + bmap->n_div);
+
+ return last_ineq < last_div;
+}
+
/* Given two constraints "k" and "l" that are opposite to each other,
* except for the constant term, check if we can use them
- * to obtain an expression for one of the hitherto unknown divs.
+ * to obtain an expression for one of the hitherto unknown divs or
+ * a "better" expression for a div for which we already have an expression.
* "sum" is the sum of the constant terms of the constraints.
* If this sum is strictly smaller than the coefficient of one
* of the divs, then this pair can be used define the div.
unsigned total = 1 + isl_space_dim(bmap->dim, isl_dim_all);
for (i = 0; i < bmap->n_div; ++i) {
- if (!isl_int_is_zero(bmap->div[i][0]))
- continue;
if (isl_int_is_zero(bmap->ineq[k][total + i]))
continue;
if (isl_int_abs_ge(sum, bmap->ineq[k][total + i]))
continue;
+ if (!better_div_constraint(bmap, i, k))
+ continue;
if (!ok_to_set_div_from_bound(bmap, i, k))
break;
if (isl_int_is_pos(bmap->ineq[k][total + i]))
return NULL;
while (progress) {
progress = 0;
+ if (!bmap)
+ break;
+ if (isl_basic_map_plain_is_empty(bmap))
+ break;
bmap = isl_basic_map_normalize_constraints(bmap);
bmap = normalize_div_expressions(bmap);
bmap = remove_duplicate_divs(bmap, &progress);