[FFmpeg-devel] [PATCH] avcodec/libx264: silence -Waddress

[Ganesh Ajjanagadde]

On Thu, Sep 17, 2015 at 6:15 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
> On Thu, Sep 17, 2015 at 12:19 AM, Ganesh Ajjanagadde
> <gajjanagadde at gmail.com> wrote:
>> This patch moves the pointer validity check outside the macro,
>> and silences the -Waddress observed with GCC 5.2.
>>
>> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>> ---
>>  libavcodec/libx264.c | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
>> index 58fcfb0..c7c772e 100644
>> --- a/libavcodec/libx264.c
>> +++ b/libavcodec/libx264.c
>> @@ -346,7 +346,7 @@ static av_cold int X264_close(AVCodecContext *avctx)
>>  #define OPT_STR(opt, param)                                                   \
>>      do {                                                                      \
>>          int ret;                                                              \
>> -        if (param && (ret = x264_param_parse(&x4->params, opt, param)) < 0) { \
>> +        if ((ret = x264_param_parse(&x4->params, opt, param)) < 0) { \
>>              if(ret == X264_PARAM_BAD_NAME)                                    \
>>                  av_log(avctx, AV_LOG_ERROR,                                   \
>>                          "bad option '%s': '%s'\n", opt, param);               \
>> @@ -437,7 +437,8 @@ static av_cold int X264_init(AVCodecContext *avctx)
>>      x4->params.i_log_level          = X264_LOG_DEBUG;
>>      x4->params.i_csp                = convert_pix_fmt(avctx->pix_fmt);
>>
>> -    OPT_STR("weightp", x4->wpredp);
>> +    if (x4->wpredp)
>> +        OPT_STR("weightp", x4->wpredp);
>>
>>      if (avctx->bit_rate) {
>>          x4->params.rc.i_bitrate   = avctx->bit_rate / 1000;
>> @@ -467,7 +468,8 @@ static av_cold int X264_init(AVCodecContext *avctx)
>>              (float)avctx->rc_initial_buffer_occupancy / avctx->rc_buffer_size;
>>      }
>>
>> -    OPT_STR("level", x4->level);
>> +    if (x4->level)
>> +        OPT_STR("level", x4->level);
>>
>>      if (avctx->i_quant_factor > 0)
>>          x4->params.rc.f_ip_factor         = 1 / fabs(avctx->i_quant_factor);
>
>
> Instead of adding explicit checks here, why not make the file more
> consistent and use PARSE_X264_OPT for the things from the x4 context
> (like its already done for a bunch of other variables), and only use
> OPT_STR for the two special cases further down (without the check
> then)

The behavior then won't be identical before and after the patch; e.g
the log portion of PARSE_X264_OPT is different from that of OPT_STR.
The current patch retains identical behavior. In particular, your
change does change the "user-facing" output slightly. Unless you (or
someone else) can confirm that it is irrelevant; I do not think your
proposal is good.

>
> - Hendrik