isl_union_set_compute_schedule: fix computation of maximal number of rows

The original computation wasn't documented, but was probably wrong.
The maximal number of schedule rows is now computed in a separate
and documented function.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>

diff --git a/isl_schedule.c b/isl_schedule.c
index 7435a55..3c08e5e 100644 (file)
--- a/isl_schedule.c
+++ b/isl_schedule.c
@@ -135,6 +135,7 @@ struct isl_sched_edge {
  * n is the number of nodes
  * node is the list of nodes
  * maxvar is the maximal number of variables over all nodes
+ * max_row is the allocated number of rows in the schedule
  * n_row is the current (maximal) number of linearly independent
  *     rows in the node schedules
  * n_total_row is the current number of rows in the node schedules
@@ -175,6 +176,7 @@ struct isl_sched_graph {
        struct isl_sched_node *node;
        int n;
        int maxvar;
+       int max_row;
        int n_row;
 
        int *sorted;
@@ -372,6 +374,43 @@ static void graph_free(isl_ctx *ctx, struct isl_sched_graph *graph)
        isl_basic_set_free(graph->lp);
 }
 
+/* For each "set" on which this function is called, increment
+ * graph->n by one and update graph->maxvar.
+ */
+static int init_n_maxvar(__isl_take isl_set *set, void *user)
+{
+       struct isl_sched_graph *graph = user;
+       int nvar = isl_set_dim(set, isl_dim_set);
+
+       graph->n++;
+       if (nvar > graph->maxvar)
+               graph->maxvar = nvar;
+
+       isl_set_free(set);
+
+       return 0;
+}
+
+/* Compute the number of rows that should be allocated for the schedule.
+ * The graph can be split at most "n - 1" times, there can be at most
+ * two rows for each dimension in the iteration domains (in particular,
+ * we usually have one row, but it may be split by split_parallel),
+ * and there can be one extra row for ordering the statements.
+ * Note that if we have actually split "n - 1" times, then no ordering
+ * is needed, so in principle we could use "graph->n + 2 * graph->maxvar - 1".
+ */
+static int compute_max_row(struct isl_sched_graph *graph,
+       __isl_keep isl_union_set *domain)
+{
+       graph->n = 0;
+       graph->maxvar = 0;
+       if (isl_union_set_foreach_set(domain, &init_n_maxvar, graph) < 0)
+               return -1;
+       graph->max_row = graph->n + 2 * graph->maxvar;
+
+       return 0;
+}
+
 /* Add a new node to the graph representing the given set.
  */
 static int extract_node(__isl_take isl_set *set, void *user)
@@ -396,11 +435,11 @@ static int extract_node(__isl_take isl_set *set, void *user)
        graph->node[graph->n].nparam = nparam;
        graph->node[graph->n].sched = sched;
        graph->node[graph->n].sched_map = NULL;
-       band = isl_alloc_array(ctx, int, graph->n_edge + nvar);
+       band = isl_alloc_array(ctx, int, graph->max_row);
        graph->node[graph->n].band = band;
-       band_id = isl_calloc_array(ctx, int, graph->n_edge + nvar);
+       band_id = isl_calloc_array(ctx, int, graph->max_row);
        graph->node[graph->n].band_id = band_id;
-       zero = isl_calloc_array(ctx, int, graph->n_edge + nvar);
+       zero = isl_calloc_array(ctx, int, graph->max_row);
        graph->node[graph->n].zero = zero;
        graph->n++;
 
@@ -2556,6 +2595,8 @@ __isl_give isl_schedule *isl_union_set_compute_schedule(
        if (graph_alloc(ctx, &graph, graph.n,
            isl_union_map_n_map(validity) + isl_union_map_n_map(proximity)) < 0)
                goto error;
+       if (compute_max_row(&graph, domain) < 0)
+               goto error;
        graph.root = 1;
        graph.n = 0;
        if (isl_union_set_foreach_set(domain, &extract_node, &graph) < 0)