From 6fd2691af8b426078996469960834e9bdd65ab9d Mon Sep 17 00:00:00 2001
From: Sven Verdoolaege <skimo@kotnet.org>
Date: Sat, 28 Nov 2009 19:47:58 +0100
Subject: [PATCH] isl_tab: add isl_tab_freeze_constraint

---
 isl_map_simplify.c |  3 ++-
 isl_tab.c          | 24 ++++++++++++++++++++++++
 isl_tab.h          |  3 +++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/isl_map_simplify.c b/isl_map_simplify.c
index 354de119..e17dffb9 100644
--- a/isl_map_simplify.c
+++ b/isl_map_simplify.c
@@ -1576,7 +1576,8 @@ static struct isl_basic_set *uset_gist(struct isl_basic_set *bset,
 	if (!tab)
 		goto error;
 	for (i = 0; i < context_ineq; ++i)
-		tab->con[i].frozen = 1;
+		if (isl_tab_freeze_constraint(tab, i) < 0)
+			goto error;
 	tab = isl_tab_extend(tab, bset->n_ineq);
 	if (!tab)
 		goto error;
diff --git a/isl_tab.c b/isl_tab.c
index 38a3aef1..2583e091 100644
--- a/isl_tab.c
+++ b/isl_tab.c
@@ -936,6 +936,26 @@ int isl_tab_mark_empty(struct isl_tab *tab)
 	return 0;
 }
 
+int isl_tab_freeze_constraint(struct isl_tab *tab, int con)
+{
+	struct isl_tab_var *var;
+
+	if (!tab)
+		return -1;
+
+	var = &tab->con[con];
+	if (var->frozen)
+		return 0;
+	if (var->index < 0)
+		return 0;
+	var->frozen = 1;
+
+	if (tab->need_undo)
+		return isl_tab_push_var(tab, isl_tab_undo_freeze, var);
+
+	return 0;
+}
+
 /* Update the rows signs after a pivot of "row" and "col", with "row_sgn"
  * the original sign of the pivot element.
  * We only keep track of row signs during PILP solving and in this case
@@ -2628,6 +2648,9 @@ static int perform_undo_var(struct isl_tab *tab, struct isl_tab_undo *undo)
 		var->is_redundant = 0;
 		tab->n_redundant--;
 		break;
+	case isl_tab_undo_freeze:
+		var->frozen = 0;
+		break;
 	case isl_tab_undo_zero:
 		var->is_zero = 0;
 		if (!var->is_row)
@@ -2748,6 +2771,7 @@ static int perform_undo(struct isl_tab *tab, struct isl_tab_undo *undo)
 		break;
 	case isl_tab_undo_nonneg:
 	case isl_tab_undo_redundant:
+	case isl_tab_undo_freeze:
 	case isl_tab_undo_zero:
 	case isl_tab_undo_allocate:
 	case isl_tab_undo_relax:
diff --git a/isl_tab.h b/isl_tab.h
index 9f55e0cc..920dea75 100644
--- a/isl_tab.h
+++ b/isl_tab.h
@@ -22,6 +22,7 @@ enum isl_tab_undo_type {
 	isl_tab_undo_empty,
 	isl_tab_undo_nonneg,
 	isl_tab_undo_redundant,
+	isl_tab_undo_freeze,
 	isl_tab_undo_zero,
 	isl_tab_undo_allocate,
 	isl_tab_undo_relax,
@@ -183,6 +184,8 @@ int isl_tab_add_ineq(struct isl_tab *tab, isl_int *ineq) WARN_UNUSED;
 struct isl_tab *isl_tab_add_eq(struct isl_tab *tab, isl_int *eq) WARN_UNUSED;
 struct isl_tab *isl_tab_add_valid_eq(struct isl_tab *tab, isl_int *eq) WARN_UNUSED;
 
+int isl_tab_freeze_constraint(struct isl_tab *tab, int con) WARN_UNUSED;
+
 int isl_tab_is_equality(struct isl_tab *tab, int con);
 int isl_tab_is_redundant(struct isl_tab *tab, int con);
 
-- 
2.11.4.GIT