i965: Make bblock_t::next and friends return NULL at sentinels.

The bblock_t::prev/prev_const/next/next_const API returns bblock_t
pointers, rather than exec_nodes.  So it's a bit surprising.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>
Reviewed-by: Matt Turner <[email protected]>

2 files changed, 13 insertions, 1 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_cfg.h b/src/mesa/drivers/dri/i965/brw_cfg.h
index 405020b77e5..5b770aa7af1 100644
--- a/src/mesa/drivers/dri/i965/brw_cfg.h
+++ b/src/mesa/drivers/dri/i965/brw_cfg.h
@@ -121,24 +121,36 @@ bblock_end_const(const struct bblock_t *block)
 static inline struct bblock_t *
 bblock_next(struct bblock_t *block)
 {
+   if (exec_node_is_tail_sentinel(block->link.next))
+      return NULL;
+
    return (struct bblock_t *)block->link.next;
 }
 
 static inline const struct bblock_t *
 bblock_next_const(const struct bblock_t *block)
 {
+   if (exec_node_is_tail_sentinel(block->link.next))
+      return NULL;
+
    return (const struct bblock_t *)block->link.next;
 }
 
 static inline struct bblock_t *
 bblock_prev(struct bblock_t *block)
 {
+   if (exec_node_is_head_sentinel(block->link.prev))
+      return NULL;
+
    return (struct bblock_t *)block->link.prev;
 }
 
 static inline const struct bblock_t *
 bblock_prev_const(const struct bblock_t *block)
 {
+   if (exec_node_is_head_sentinel(block->link.prev))
+      return NULL;
+
    return (const struct bblock_t *)block->link.prev;
 }
 
diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp
index 736deb443dd..376cb258232 100644
--- a/src/mesa/drivers/dri/i965/brw_shader.cpp
+++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
@@ -938,7 +938,7 @@ static void
 adjust_later_block_ips(bblock_t *start_block, int ip_adjustment)
 {
    for (bblock_t *block_iter = start_block->next();
-        !block_iter->link.is_tail_sentinel();
+        block_iter;
         block_iter = block_iter->next()) {
       block_iter->start_ip += ip_adjustment;
       block_iter->end_ip += ip_adjustment;