| Message ID | 20200801134704.3647-13-andreas.rheinhardt@gmail.com |
|---|---|
| State | Accepted |
| Commit | 6ffc7be5da0ece247cf26f1d6b94cd1d6af3d338 |
| 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 |
On 8/1/20, Andreas Rheinhardt <andreas.rheinhardt@gmail.com> wrote: > Besides the obvious advantage of less code this also has a performance > impact: For GCC 9 the time spent on one call to smka_decode_frame() for > the sample from ticket #2425 decreased from 1693619 to 1498127 > decicycles. For Clang 9, it decreased from 1369089 to 1366465 > decicycles. > > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> > --- > The numbers for GCC surprised me (as did the fact that GCC was so much > worse than Clang). > > libavcodec/smacker.c | 62 ++++++++++++++------------------------------ > 1 file changed, 20 insertions(+), 42 deletions(-) > > diff --git a/libavcodec/smacker.c b/libavcodec/smacker.c > index d2b1c68162..ffd24c11e7 100644 > --- a/libavcodec/smacker.c > +++ b/libavcodec/smacker.c > @@ -671,37 +671,23 @@ static int smka_decode_frame(AVCodecContext *avctx, > void *data, > for(i = 0; i <= stereo; i++) > *samples++ = pred[i]; > for(; i < unp_size / 2; i++) { > + unsigned idx = 2 * (i & stereo); > if (get_bits_left(&gb) < 0) { > ret = AVERROR_INVALIDDATA; > goto error; > } > - if(i & stereo) { > - if(vlc[2].table) > - res = get_vlc2(&gb, vlc[2].table, SMKTREE_BITS, 3); > - else > - res = values[2]; > - val = res; > - if(vlc[3].table) > - res = get_vlc2(&gb, vlc[3].table, SMKTREE_BITS, 3); > - else > - res = values[3]; > - val |= res << 8; > - pred[1] += val; > - *samples++ = pred[1]; > - } else { > - if(vlc[0].table) > - res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3); > - else > - res = values[0]; > - val = res; > - if(vlc[1].table) > - res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3); > - else > - res = values[1]; > - val |= res << 8; > - pred[0] += val; > - *samples++ = pred[0]; > - } > + if (vlc[idx].table) > + res = get_vlc2(&gb, vlc[idx].table, SMKTREE_BITS, 3); > + else > + res = values[idx]; > + val = res; > + if (vlc[++idx].table) > + res = get_vlc2(&gb, vlc[idx].table, SMKTREE_BITS, 3); > + else > + res = values[idx]; > + val |= res << 8; > + pred[idx / 2] += val; > + *samples++ = pred[idx / 2]; > } > } else { //8-bit data > for(i = stereo; i >= 0; i--) > @@ -709,25 +695,17 @@ static int smka_decode_frame(AVCodecContext *avctx, > void *data, > for(i = 0; i <= stereo; i++) > *samples8++ = pred[i]; > for(; i < unp_size; i++) { > + unsigned idx = i & stereo; > if (get_bits_left(&gb) < 0) { > ret = AVERROR_INVALIDDATA; > goto error; > } > - if(i & stereo){ > - if(vlc[1].table) > - res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3); > - else > - res = values[1]; > - pred[1] += res; > - *samples8++ = pred[1]; > - } else { > - if(vlc[0].table) > - res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3); > - else > - res = values[0]; > - pred[0] += res; > - *samples8++ = pred[0]; > - } > + if (vlc[idx].table) > + val = get_vlc2(&gb, vlc[idx].table, SMKTREE_BITS, 3); > + else > + val = values[idx]; > + pred[idx] += val; > + *samples8++ = pred[idx]; > } > } > > -- > 2.20.1 > LGTM > _______________________________________________ > 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 d2b1c68162..ffd24c11e7 100644 --- a/libavcodec/smacker.c +++ b/libavcodec/smacker.c @@ -671,37 +671,23 @@ static int smka_decode_frame(AVCodecContext *avctx, void *data, for(i = 0; i <= stereo; i++) *samples++ = pred[i]; for(; i < unp_size / 2; i++) { + unsigned idx = 2 * (i & stereo); if (get_bits_left(&gb) < 0) { ret = AVERROR_INVALIDDATA; goto error; } - if(i & stereo) { - if(vlc[2].table) - res = get_vlc2(&gb, vlc[2].table, SMKTREE_BITS, 3); - else - res = values[2]; - val = res; - if(vlc[3].table) - res = get_vlc2(&gb, vlc[3].table, SMKTREE_BITS, 3); - else - res = values[3]; - val |= res << 8; - pred[1] += val; - *samples++ = pred[1]; - } else { - if(vlc[0].table) - res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3); - else - res = values[0]; - val = res; - if(vlc[1].table) - res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3); - else - res = values[1]; - val |= res << 8; - pred[0] += val; - *samples++ = pred[0]; - } + if (vlc[idx].table) + res = get_vlc2(&gb, vlc[idx].table, SMKTREE_BITS, 3); + else + res = values[idx]; + val = res; + if (vlc[++idx].table) + res = get_vlc2(&gb, vlc[idx].table, SMKTREE_BITS, 3); + else + res = values[idx]; + val |= res << 8; + pred[idx / 2] += val; + *samples++ = pred[idx / 2]; } } else { //8-bit data for(i = stereo; i >= 0; i--) @@ -709,25 +695,17 @@ static int smka_decode_frame(AVCodecContext *avctx, void *data, for(i = 0; i <= stereo; i++) *samples8++ = pred[i]; for(; i < unp_size; i++) { + unsigned idx = i & stereo; if (get_bits_left(&gb) < 0) { ret = AVERROR_INVALIDDATA; goto error; } - if(i & stereo){ - if(vlc[1].table) - res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3); - else - res = values[1]; - pred[1] += res; - *samples8++ = pred[1]; - } else { - if(vlc[0].table) - res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3); - else - res = values[0]; - pred[0] += res; - *samples8++ = pred[0]; - } + if (vlc[idx].table) + val = get_vlc2(&gb, vlc[idx].table, SMKTREE_BITS, 3); + else + val = values[idx]; + pred[idx] += val; + *samples8++ = pred[idx]; } }
Besides the obvious advantage of less code this also has a performance impact: For GCC 9 the time spent on one call to smka_decode_frame() for the sample from ticket #2425 decreased from 1693619 to 1498127 decicycles. For Clang 9, it decreased from 1369089 to 1366465 decicycles. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> --- The numbers for GCC surprised me (as did the fact that GCC was so much worse than Clang). libavcodec/smacker.c | 62 ++++++++++++++------------------------------ 1 file changed, 20 insertions(+), 42 deletions(-)