[Mesa-dev] [PATCH 1/5] nir: Make nir_block_{first, last}_instr return NULL for empty blocks.

[Jason Ekstrand]

On Thu, Aug 27, 2015 at 11:45 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> On Tue, Aug 25, 2015 at 1:24 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
>> This is a lot more reasonable than returning an offset from NULL.
>>
>> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
>> ---
>>  src/glsl/nir/nir.h | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
>> index 40871f7..12ddeb2 100644
>> --- a/src/glsl/nir/nir.h
>> +++ b/src/glsl/nir/nir.h
>> @@ -1219,14 +1219,14 @@ static inline nir_instr *
>>  nir_block_first_instr(nir_block *block)
>>  {
>>     struct exec_node *head = exec_list_get_head(&block->instr_list);
>> -   return exec_node_data(nir_instr, head, node);
>> +   return head ? exec_node_data(nir_instr, head, node) : NULL;
>
> node is the first element of nir_instr so this is a no-op.  Perhaps we
> should instead just add a
>
> STATIC_ASSERT(offsetof(nir_instr, node) == 0)
>
> and a comment.

Other than that, the series is

Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>

The TGSI stuff seems sane but it'd be good to test it.
--Jason

>
>>  }
>>
>>  static inline nir_instr *
>>  nir_block_last_instr(nir_block *block)
>>  {
>>     struct exec_node *tail = exec_list_get_tail(&block->instr_list);
>> -   return exec_node_data(nir_instr, tail, node);
>> +   return tail ? exec_node_data(nir_instr, tail, node) : NULL;
>>  }
>>
>>  #define nir_foreach_instr(block, instr) \
>> --
>> 2.5.0
>>
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