Simplify liveness validation.

This also fixes a possible null pointer access.

ir/be/beverify.c

@@ -764,32 +764,24 @@ static const char *lv_flags_to_str(unsigned flags)
 
 static void lv_check_walker(ir_node *bl, void *data)
 {
-	lv_walker_t  *const w    = (lv_walker_t*)data;
-	be_lv_info_t *const curr = ir_nodehashmap_get(be_lv_info_t, &w->given->map, bl);
-	be_lv_info_t *const fr   = ir_nodehashmap_get(be_lv_info_t, &w->fresh->map, bl);
-
-	if (!fr && curr && curr->n_members > 0) {
-		ir_fprintf(stderr, "%+F liveness should be empty but current liveness contains:\n", bl);
-		for (unsigned i = 0; i < curr->n_members; ++i) {
-			ir_fprintf(stderr, "\t%+F\n", curr->nodes[i].node);
+	lv_walker_t    *const w       = (lv_walker_t*)data;
+	be_lv_info_t   *const curr    = ir_nodehashmap_get(be_lv_info_t, &w->given->map, bl);
+	be_lv_info_t   *const fresh   = ir_nodehashmap_get(be_lv_info_t, &w->fresh->map, bl);
+	unsigned const        n_curr  = curr  ? curr->n_members  : 0;
+	unsigned const        n_fresh = fresh ? fresh->n_members : 0;
+	if (n_curr != n_fresh) {
+		ir_fprintf(stderr, "%+F: liveness set sizes differ. curr %d, correct %d\n", bl, n_curr, n_fresh);
+
+		ir_fprintf(stderr, "current:\n");
+		for (unsigned i = 0; i < n_curr; ++i) {
+			be_lv_info_node_t *const n = &curr->nodes[i];
+			ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, n->node, lv_flags_to_str(n->flags));
 		}
-	} else if (curr) {
-		unsigned const n_curr  = curr->n_members;
-		unsigned const n_fresh = fr->n_members;
-		if (n_curr != n_fresh) {
-			ir_fprintf(stderr, "%+F: liveness set sizes differ. curr %d, correct %d\n", bl, n_curr, n_fresh);
-
-			ir_fprintf(stderr, "current:\n");
-			for (unsigned i = 0; i < n_curr; ++i) {
-				be_lv_info_node_t *const n = &curr->nodes[i];
-				ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, n->node, lv_flags_to_str(n->flags));
-			}
 
-			ir_fprintf(stderr, "correct:\n");
-			for (unsigned i = 0; i < n_fresh; ++i) {
-				be_lv_info_node_t *const n = &fr->nodes[i];
-				ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, n->node, lv_flags_to_str(n->flags));
-			}
+		ir_fprintf(stderr, "correct:\n");
+		for (unsigned i = 0; i < n_fresh; ++i) {
+			be_lv_info_node_t *const n = &fresh->nodes[i];
+			ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, n->node, lv_flags_to_str(n->flags));
 		}
 	}
 }