[Mesa-dev] [RFC 1/2] glsl/list: Add an iteration helper that starts after the given node

[Kenneth Graunke]

On Thursday, September 15, 2016 9:00:35 PM PDT Jason Ekstrand wrote:
> ---
>  src/compiler/glsl/list.h | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/src/compiler/glsl/list.h b/src/compiler/glsl/list.h
> index b5b5b36..8371519 100644
> --- a/src/compiler/glsl/list.h
> +++ b/src/compiler/glsl/list.h
> @@ -714,6 +714,15 @@ inline void exec_node::insert_before(exec_list *before)
>          __node = __next, __next =                                          \
>             exec_node_data(__type, (__next)->__field.next, __field))
>  

Perhaps add:

/* __after must be a valid list node (not the tail sentinel) */

(if after is the tail sentinel, __node will be NULL, and then trying to
obtain (__node)->__field.next will dereference that NULL pointer.)

Either way, patch 1 is
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

(I haven't thought about patch 2, sorry)

> +#define foreach_list_typed_safe_after(__type, __node, __field, __after)    \
> +   for (__type * __node =                                                  \
> +           exec_node_data(__type, (__after)->__field.next, __field),       \
> +               * __next =                                                  \
> +           exec_node_data(__type, (__node)->__field.next, __field);        \
> +        (__node)->__field.next != NULL;                                    \
> +        __node = __next, __next =                                          \
> +           exec_node_data(__type, (__next)->__field.next, __field))
> +
>  #define foreach_list_typed_reverse_safe(__type, __node, __field, __list)   \
>     for (__type * __node =                                                  \
>             exec_node_data(__type, (__list)->tail_sentinel.prev, __field),  \
> 

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