1 files changed, 27 insertions, 6 deletions

diff --git a/polly/lib/External/isl/isl_tarjan.c b/polly/lib/External/isl/isl_tarjan.c
index 414a2e09cc2..a958c016e0b 100644
--- a/polly/lib/External/isl/isl_tarjan.c
+++ b/polly/lib/External/isl/isl_tarjan.c
@@ -14,14 +14,15 @@
 #include <isl/ctx.h>
 #include <isl_tarjan.h>
 
-void isl_tarjan_graph_free(struct isl_tarjan_graph *g)
+struct isl_tarjan_graph *isl_tarjan_graph_free(struct isl_tarjan_graph *g)
 {
 	if (!g)
-		return;
+		return NULL;
 	free(g->node);
 	free(g->stack);
 	free(g->order);
 	free(g);
+	return NULL;
 }
 
 static struct isl_tarjan_graph *isl_tarjan_graph_alloc(isl_ctx *ctx, int len)
@@ -128,11 +129,31 @@ struct isl_tarjan_graph *isl_tarjan_graph_init(isl_ctx *ctx, int len,
 		if (g->node[i].index >= 0)
 			continue;
 		if (isl_tarjan_components(g, i, follows, user) < 0)
-			goto error;
+			return isl_tarjan_graph_free(g);
 	}
 
 	return g;
-error:
-	isl_tarjan_graph_free(g);
-	return NULL;
+}
+
+/* Decompose the graph with "len" nodes and edges defined by "follows"
+ * into the strongly connected component (SCC) that contains "node"
+ * as well as all SCCs that are followed by this SCC.
+ * follows(i, j, user) should return 1 if "i" follows "j" and 0 otherwise.
+ * It should return -1 on error.
+ *
+ * The SCC containing "node" will appear as the last component
+ * in g->order.
+ */
+struct isl_tarjan_graph *isl_tarjan_graph_component(isl_ctx *ctx, int len,
+	int node, isl_bool (*follows)(int i, int j, void *user), void *user)
+{
+	struct isl_tarjan_graph *g;
+
+	g = isl_tarjan_graph_alloc(ctx, len);
+	if (!g)
+		return NULL;
+	if (isl_tarjan_components(g, node, follows, user) < 0)
+		return isl_tarjan_graph_free(g);
+
+	return g;
 }