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commit cd8ece41149037a525d0c0c2cc54bfe3350e9b20 Author: Niklas Haas <[email protected]> AuthorDate: Tue Apr 14 14:35:22 2026 +0200 Commit: Niklas Haas <[email protected]> CommitDate: Thu Apr 16 20:59:39 2026 +0000 swscale/ops_dispatch: generalize the number of tail blocks This is a mostly straightforward internal mechanical change that I wanted to isolate from the following commit to make bisection easier in the case of regressions. While the number of tail blocks could theoretically be different for input vs output memcpy, the extra complexity of handling that mismatch (and adjusting all of the tail offsets, strides etc.) seems not worth it. I tested this commit by manually setting `p->tail_blocks` to higher values and seeing if that still passed the self-check under valgrind. Signed-off-by: Niklas Haas <[email protected]> --- libswscale/ops_dispatch.c | 38 +++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 15 deletions(-) diff --git a/libswscale/ops_dispatch.c b/libswscale/ops_dispatch.c index fa24283db2..a0d3da6cc3 100644 --- a/libswscale/ops_dispatch.c +++ b/libswscale/ops_dispatch.c @@ -49,6 +49,7 @@ typedef struct SwsOpPass { bool memcpy_first; bool memcpy_last; bool memcpy_out; + size_t tail_blocks; uint8_t *tail_buf; /* extra memory for fixing unpadded tails */ unsigned int tail_buf_size; } SwsOpPass; @@ -220,8 +221,10 @@ static int op_pass_setup(const SwsFrame *out, const SwsFrame *in, size_t alloc_size = 0; *tail = *exec; - av_assert0(num_blocks >= 1); - const size_t safe_width = (num_blocks - 1) * block_size; + p->tail_blocks = 1; + av_assert0(num_blocks >= p->tail_blocks); + + const size_t safe_width = (num_blocks - p->tail_blocks) * block_size; const size_t tail_size = pass->width - safe_width; p->tail_off_out = pixel_bytes(safe_width, p->pixel_bits_out, AV_ROUND_DOWN); p->tail_size_out = pixel_bytes(tail_size, p->pixel_bits_out, AV_ROUND_UP); @@ -246,15 +249,17 @@ static int op_pass_setup(const SwsFrame *out, const SwsFrame *in, } else { needed_size = pixel_bytes(alloc_width, p->pixel_bits_in, AV_ROUND_UP); } + size_t loop_size = p->tail_blocks * exec->block_size_in; tail->in_stride[i] = FFALIGN(needed_size + comp->over_read, align); - tail->in_bump[i] = tail->in_stride[i] - exec->block_size_in; + tail->in_bump[i] = tail->in_stride[i] - loop_size; alloc_size += tail->in_stride[i] * in->height; } for (int i = 0; p->memcpy_out && i < p->planes_out; i++) { - size_t needed_size = pixel_bytes(alloc_width, p->pixel_bits_out, AV_ROUND_UP); + size_t needed_size = pixel_bytes(alloc_width, p->pixel_bits_out, AV_ROUND_UP); + size_t loop_size = p->tail_blocks * exec->block_size_out; tail->out_stride[i] = FFALIGN(needed_size + comp->over_write, align); - tail->out_bump[i] = tail->out_stride[i] - exec->block_size_out; + tail->out_bump[i] = tail->out_stride[i] - loop_size; alloc_size += tail->out_stride[i] * out->height; } @@ -329,7 +334,8 @@ static void op_pass_run(const SwsFrame *out, const SwsFrame *in, const int y, const bool memcpy_in = p->memcpy_last && y + h == pass->height || p->memcpy_first && y == 0; const bool memcpy_out = p->memcpy_out; - const size_t num_blocks = p->num_blocks; + const size_t num_blocks = p->num_blocks; + const size_t tail_blocks = p->tail_blocks; get_row_data(p, y, exec.in, exec.out); if (!memcpy_in && !memcpy_out) { @@ -338,18 +344,18 @@ static void op_pass_run(const SwsFrame *out, const SwsFrame *in, const int y, return; } - /* Non-aligned case (slow path); process num_blocks - 1 main blocks and + /* Non-aligned case (slow path); process main blocks as normal, and * a separate tail (via memcpy into an appropriately padded buffer) */ - if (num_blocks > 1) { + if (num_blocks > tail_blocks) { for (int i = 0; i < 4; i++) { - /* We process one fewer block, so the in_bump needs to be increased + /* We process fewer blocks, so the in_bump needs to be increased * to reflect that the plane pointers are left on the last block, * not the end of the processed line, after each loop iteration */ - exec.in_bump[i] += exec.block_size_in; - exec.out_bump[i] += exec.block_size_out; + exec.in_bump[i] += exec.block_size_in * tail_blocks; + exec.out_bump[i] += exec.block_size_out * tail_blocks; } - comp->func(&exec, comp->priv, 0, y, num_blocks - 1, y + h); + comp->func(&exec, comp->priv, 0, y, num_blocks - tail_blocks, y + h); } DECLARE_ALIGNED_32(SwsOpExec, tail) = p->exec_tail; @@ -373,21 +379,23 @@ static void op_pass_run(const SwsFrame *out, const SwsFrame *in, const int y, exec.in[i], exec.in_stride[i], h, p->tail_size_in); } else { /* Reuse input pointers directly */ + const size_t loop_size = tail_blocks * exec.block_size_in; tail.in[i] = exec.in[i]; tail.in_stride[i] = exec.in_stride[i]; - tail.in_bump[i] = exec.in_stride[i] - exec.block_size_in; + tail.in_bump[i] = exec.in_stride[i] - loop_size; } } for (int i = 0; !memcpy_out && i < p->planes_out; i++) { /* Reuse output pointers directly */ + const size_t loop_size = tail_blocks * exec.block_size_out; tail.out[i] = exec.out[i]; tail.out_stride[i] = exec.out_stride[i]; - tail.out_bump[i] = exec.out_stride[i] - exec.block_size_out; + tail.out_bump[i] = exec.out_stride[i] - loop_size; } /* Dispatch kernel over tail */ - comp->func(&tail, comp->priv, num_blocks - 1, y, num_blocks, y + h); + comp->func(&tail, comp->priv, num_blocks - tail_blocks, y, num_blocks, y + h); for (int i = 0; memcpy_out && i < p->planes_out; i++) { copy_lines(exec.out[i], exec.out_stride[i], _______________________________________________ ffmpeg-cvslog mailing list -- [email protected] To unsubscribe send an email to [email protected]
