Make reorder_node() more clear (at least to me).

[r22512]

diff --git a/heuristical.c b/heuristical.c
index 7605ffb..973dc03 100644 (file)
--- a/heuristical.c
+++ b/heuristical.c
@@ -158,9 +158,12 @@ static void normalize_towards_target(pbqp *pbqp, pbqp_edge *edge)
 
 static void reorder_node(pbqp_node *node)
 {
-       unsigned arity;
-       unsigned old_arity;
-       unsigned old_bucket_len;
+       unsigned    arity;
+       unsigned    old_arity;
+       unsigned    old_bucket_len;
+       unsigned    old_bucket_index;
+       pbqp_node **old_bucket;
+       pbqp_node  *other;
 
        if (!buckets_filled) return;
 
@@ -168,31 +171,34 @@ static void reorder_node(pbqp_node *node)
 
        arity = ARR_LEN(node->edges);
 
-       /* Equal bucket as before */
+       /* Same bucket as before */
        if (arity > 2) return;
 
        /* Assume node lost one incident edge. */
-       old_arity = arity + 1;
+       old_arity        = arity + 1;
+       old_bucket       = node_buckets[old_arity];
+       old_bucket_len   = ARR_LEN(old_bucket);
+       old_bucket_index = node->bucket_index;
 
-       if (ARR_LEN(node_buckets[old_arity]) <= (int)node->bucket_index
-                       || node_buckets[old_arity][node->bucket_index] != node) {
+       if (old_bucket_len <= old_bucket_index ||
+           old_bucket[old_bucket_index] != node) {
                /* Old arity is new arity, so we have nothing to do. */
+               assert(old_bucket_index < ARR_LEN(node_buckets[arity]) &&
+                      node_buckets[arity][old_bucket_index] == node);
                return;
        }
 
-       old_bucket_len = ARR_LEN(node_buckets[old_arity]);
-       assert (node_buckets[old_arity][node->bucket_index] == node);
+       assert(old_bucket[old_bucket_index] == node);
 
        /* Delete node from old bucket... */
-       node_buckets[old_arity][old_bucket_len - 1]->bucket_index
-                       = node->bucket_index;
-       node_buckets[old_arity][node->bucket_index]
-                       = node_buckets[old_arity][old_bucket_len - 1];
-       ARR_SHRINKLEN(node_buckets[old_arity], (int)old_bucket_len - 1);
+       other                        = old_bucket[old_bucket_len - 1];
+       other->bucket_index          = old_bucket_index;
+       old_bucket[old_bucket_index] = other;
+       ARR_SHRINKLEN(node_buckets[old_arity], old_bucket_len - 1);
 
        /* ..and add to new one. */
        node->bucket_index = ARR_LEN(node_buckets[arity]);
-       ARR_APP1(pbqp_node *, node_buckets[arity], node);
+       ARR_APP1(pbqp_node*, node_buckets[arity], node);
 }
 
 static void simplify_edge(pbqp *pbqp, pbqp_edge *edge)