From d028a266c37e167dbe7b838fae63b4b380f421d2 Mon Sep 17 00:00:00 2001
From: Sven Verdoolaege <skimo@kotnet.org>
Date: Fri, 26 Sep 2008 10:06:15 +0200
Subject: [PATCH] add isl_set_fast_dim_has_fixed_lower_bound

---
 include/isl_set.h |  2 ++
 isl_map.c         | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/include/isl_set.h b/include/isl_set.h
index ec0626f..a4262d0 100644
--- a/include/isl_set.h
+++ b/include/isl_set.h
@@ -150,6 +150,8 @@ struct isl_set *isl_set_drop_basic_set(struct isl_set *set,
 						struct isl_basic_set *bset);
 
 int isl_set_fast_dim_is_fixed(struct isl_set *set, unsigned dim, isl_int *val);
+int isl_set_fast_dim_has_fixed_lower_bound(struct isl_set *set,
+	unsigned dim, isl_int *val);
 
 struct isl_set *isl_set_gist(struct isl_set *set,
 	struct isl_basic_set *context);
diff --git a/isl_map.c b/isl_map.c
index 8c646e7..47a1218 100644
--- a/isl_map.c
+++ b/isl_map.c
@@ -3798,6 +3798,81 @@ int isl_map_fast_input_is_fixed(struct isl_map *map, unsigned in, isl_int *val)
 	return isl_map_fast_has_fixed_var(map, map->nparam + in, val);
 }
 
+/* Check if dimension dim has an (obvious) fixed lower bound and if so
+ * and if val is not NULL, then return this lower bound in *val.
+ */
+int isl_basic_set_fast_dim_has_fixed_lower_bound(struct isl_basic_set *bset,
+	unsigned dim, isl_int *val)
+{
+	int i, i_eq = -1, i_ineq = -1;
+	isl_int *c;
+	unsigned total;
+
+	if (!bset)
+		return -1;
+	total = bset->nparam + bset->dim + bset->n_div;
+	for (i = 0; i < bset->n_eq; ++i) {
+		if (isl_int_is_zero(bset->eq[i][1+bset->nparam+dim]))
+			continue;
+		if (i_eq != -1)
+			return 0;
+		i_eq = i;
+	}
+	for (i = 0; i < bset->n_ineq; ++i) {
+		if (!isl_int_is_pos(bset->ineq[i][1+bset->nparam+dim]))
+			continue;
+		if (i_eq != -1 || i_ineq != -1)
+			return 0;
+		i_ineq = i;
+	}
+	if (i_eq == -1 && i_ineq == -1)
+		return 0;
+	c = i_eq != -1 ? bset->eq[i_eq] : bset->ineq[i_ineq];
+	/* The coefficient should always be one due to normalization. */
+	if (!isl_int_is_one(c[1+bset->nparam+dim]))
+		return 0;
+	if (isl_seq_first_non_zero(c+1, bset->nparam+dim) != -1)
+		return 0;
+	if (isl_seq_first_non_zero(c+1+bset->nparam+dim+1,
+					total - bset->nparam - dim - 1) != -1)
+		return 0;
+	if (val)
+		isl_int_neg(*val, c[0]);
+	return 1;
+}
+
+int isl_set_fast_dim_has_fixed_lower_bound(struct isl_set *set,
+	unsigned dim, isl_int *val)
+{
+	int i;
+	isl_int v;
+	isl_int tmp;
+	int fixed;
+
+	if (!set)
+		return -1;
+	if (set->n == 0)
+		return 0;
+	if (set->n == 1)
+		return isl_basic_set_fast_dim_has_fixed_lower_bound(set->p[0],
+								dim, val);
+	isl_int_init(v);
+	isl_int_init(tmp);
+	fixed = isl_basic_set_fast_dim_has_fixed_lower_bound(set->p[0],
+								dim, &v);
+	for (i = 1; fixed == 1 && i < set->n; ++i) {
+		fixed = isl_basic_set_fast_dim_has_fixed_lower_bound(set->p[i],
+								dim, &tmp);
+		if (fixed == 1 && isl_int_ne(tmp, v))
+			fixed = 0;
+	}
+	if (val)
+		isl_int_set(*val, v);
+	isl_int_clear(tmp);
+	isl_int_clear(v);
+	return fixed;
+}
+
 /* Remove all information from bset that is redundant in the context
  * of context.  In particular, equalities that are linear combinations
  * of those in context are remobed.  Then the inequalities that are
-- 
2.7.4