On Mon, Mar 9, 2015 at 11:06 PM, Matt Turner <matts...@gmail.com> wrote:
> On Mon, Mar 9, 2015 at 6:36 PM, Kenneth Graunke <kenn...@whitecape.org> > wrote: > > From: Jason Ekstrand <jason.ekstr...@intel.com> > > > > __next and __prev are pointers to the structure containing the exec_node > > link, not the embedded exec_node. NULL checks would fail unless the > > embedded exec_node happened to be at offset 0 in the parent struct. > > > > Signed-off-by: Jason Ekstrand <jason.ekstr...@intel.com> > > Reviewed-by: Kenneth Graunke <kenn...@whitecape.org> > > --- > > src/glsl/list.h | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/src/glsl/list.h b/src/glsl/list.h > > index ddb98f7..680e963 100644 > > --- a/src/glsl/list.h > > +++ b/src/glsl/list.h > > @@ -684,7 +684,7 @@ inline void exec_node::insert_before(exec_list > *before) > > exec_node_data(__type, (__list)->head, __field), > \ > > * __next = > \ > > exec_node_data(__type, (__node)->__field.next, __field); > \ > > - __next != NULL; > \ > > + &__next->__field != NULL; > \ > > Wow. Okay, so this apparently relies on exec_node_data (which is > pretty confusingly named, I think) returning a negative pointer value > if passed NULL as its node parameter, such that &...->__field > effectively adds back the offset of the field in the struct, giving a > NULL pointer? > > That's sufficiently confusing to warrant a lengthy comment at the very > least. > > Testing that the address of a field in a struct is NULL... just looks > insane. > How about we do things slightly differently and check "(__node)->field.next != NULL" just like we do on regular versions. Since the check happens between the increment step and running the user's code, __node is valid for every invocation of the checking condition. Would that make you feel better about it? --Jason _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/mesa-dev >
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