| Message ID | 20200801134704.3647-4-andreas.rheinhardt@gmail.com |
|---|---|
| State | Accepted |
| Commit | 943a4581570728b4b1a2bf97e5601e24f3f80404 |
| Headers | show |
| Series | [FFmpeg-devel,1/8] avcodec/smacker: Remove write-only and unused variables | expand |
| Context | Check | Description |
|---|---|---|
| andriy/default | pending | |
| andriy/make | success | Make finished |
| andriy/make_fate | success | Make fate finished |
probably fine On 8/1/20, Andreas Rheinhardt <andreas.rheinhardt@gmail.com> wrote: > When length is zero for a leaf node (which happens iff the Huffman tree > consists of one leaf node only), prefix is also automatically zero. > > Performance impact is negligible: For GCC 9 and the sample from #2425, > the time for one call to smka_decode_frame() decreased from 2053758 to > 2053671 decicycles; for Clang 9 it went from 1523153 to 1521288. > > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> > --- > libavcodec/smacker.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/libavcodec/smacker.c b/libavcodec/smacker.c > index c249ce7514..991622eb0e 100644 > --- a/libavcodec/smacker.c > +++ b/libavcodec/smacker.c > @@ -105,13 +105,8 @@ static int smacker_decode_tree(GetBitContext *gb, > HuffContext *hc, uint32_t pref > av_log(NULL, AV_LOG_ERROR, "Tree size exceeded!\n"); > return AVERROR_INVALIDDATA; > } > - if(length){ > - hc->bits[hc->current] = prefix; > - hc->lengths[hc->current] = length; > - } else { > - hc->bits[hc->current] = 0; > - hc->lengths[hc->current] = 0; > - } > + hc->bits[hc->current] = prefix; > + hc->lengths[hc->current] = length; > hc->values[hc->current] = get_bits(gb, 8); > hc->current++; > return 0; > -- > 2.20.1 > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
diff --git a/libavcodec/smacker.c b/libavcodec/smacker.c index c249ce7514..991622eb0e 100644 --- a/libavcodec/smacker.c +++ b/libavcodec/smacker.c @@ -105,13 +105,8 @@ static int smacker_decode_tree(GetBitContext *gb, HuffContext *hc, uint32_t pref av_log(NULL, AV_LOG_ERROR, "Tree size exceeded!\n"); return AVERROR_INVALIDDATA; } - if(length){ - hc->bits[hc->current] = prefix; - hc->lengths[hc->current] = length; - } else { - hc->bits[hc->current] = 0; - hc->lengths[hc->current] = 0; - } + hc->bits[hc->current] = prefix; + hc->lengths[hc->current] = length; hc->values[hc->current] = get_bits(gb, 8); hc->current++; return 0;
When length is zero for a leaf node (which happens iff the Huffman tree consists of one leaf node only), prefix is also automatically zero. Performance impact is negligible: For GCC 9 and the sample from #2425, the time for one call to smka_decode_frame() decreased from 2053758 to 2053671 decicycles; for Clang 9 it went from 1523153 to 1521288. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> --- libavcodec/smacker.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)