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Optimize SkWuffsCodec pixbuf zero-initialization

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Pushing the zero-initialization into the sk_malloc_etc call can be more
efficient than a two-step malloc-and-then-memset, e.g. if the memory
allocator gives us something from an already-known-zeroed region.

Some microbenchmark numbers (milliseconds per decode) from running
Chromium's image_decode_bench program on a few GIF files:

Before  After   Ratio   Filename        Width x Height = Pixels
 0.109   0.107  1.02    hat.gif           90  x  112   =   10080
 7.062   6.879  1.03    harvesters.gif  1165  x  859   = 1000735
33.342  30.544  1.09    droids.gif      2560  x 1920   = 4915200

Ratio > 1.00 means a performance improvement.

image_decode_bench comes from:
https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/testing/image_decode_bench.cc

hat.gif and harvesters.gif come from:
https://github.com/google/wuffs/tree/master/test/data

droids.gif comes from:
https://cs.chromium.org/chromium/src/third_party/blink/perf_tests/image_decoder/resources/

These are x86_64 Broadwell numbers. I don't have ARM numbers readily
available, but nothing about this commit should be arch-specific.

Bug: skia:8235
Change-Id: Icf45b7ac5b7194eaab455628e44d4aedf30ddbfe
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/254836
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
This commit is contained in:
Nigel Tao 2019-11-15 15:27:44 +11:00 committed by Skia Commit-Bot
parent 301015ce1e
commit 39da10b556
1 changed files with 26 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
src/codec/SkWuffsCodec.cpp
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@ -132,7 +132,6 @@ static SkCodec::Result reset_and_decode_image_config(wuffs_gif__decoder* d
return SkCodec::kSuccess;
}
// -------------------------------- Class definitions
class SkWuffsCodec;
@ -179,6 +178,7 @@ public:
std::unique_ptr<SkStream> stream,
std::unique_ptr<wuffs_gif__decoder, decltype(&sk_free)> dec,
std::unique_ptr<uint8_t, decltype(&sk_free)> pixbuf_ptr,
bool pixbuf_zeroed,
std::unique_ptr<uint8_t, decltype(&sk_free)> workbuf_ptr,
size_t workbuf_len,
wuffs_base__image_config imgcfg,
@ -266,6 +266,10 @@ private:
std::vector<SkWuffsFrame> fFrames;
bool fFramesComplete;
// True if fPixelBuffer's contents are known to be already zeroed. This is
// conservative, and may be false even if the buffer is zeroed.
bool fPixbufZeroed;
// If calling an fDecoders[which] method returns an incomplete status, then
// fDecoders[which] is suspended in a coroutine (i.e. waiting on I/O or
// halted on a non-recoverable error). To keep its internal proof-of-safety
@ -333,6 +337,7 @@ SkWuffsCodec::SkWuffsCodec(SkEncodedInfo&&
std::unique_ptr<SkStream> stream,
std::unique_ptr<wuffs_gif__decoder, decltype(&sk_free)> dec,
std::unique_ptr<uint8_t, decltype(&sk_free)> pixbuf_ptr,
bool pixbuf_zeroed,
std::unique_ptr<uint8_t, decltype(&sk_free)> workbuf_ptr,
size_t workbuf_len,
wuffs_base__image_config imgcfg,
@ -367,6 +372,7 @@ SkWuffsCodec::SkWuffsCodec(SkEncodedInfo&&
fFrameCountReaderIOPosition(0),
fNumFullyReceivedFrames(0),
fFramesComplete(false),
fPixbufZeroed(pixbuf_zeroed),
fDecoderIsSuspended{
false,
false,
@ -443,12 +449,20 @@ SkCodec::Result SkWuffsCodec::onStartIncrementalDecode(const SkImageInfo& d
size_t src_bytes_per_pixel = src_bits_per_pixel / 8;
// Zero-initialize Wuffs' buffer covering the frame rect.
if (!fPixbufZeroed) {
wuffs_base__rect_ie_u32 frame_rect = fFrameConfigs[WhichDecoder::kIncrDecode].bounds();
wuffs_base__table_u8 pixels = fPixelBuffer.plane(0);
for (uint32_t y = frame_rect.min_incl_y; y < frame_rect.max_excl_y; y++) {
sk_bzero(pixels.ptr + (y * pixels.stride) + (frame_rect.min_incl_x * src_bytes_per_pixel),
sk_bzero(
pixels.ptr + (y * pixels.stride) + (frame_rect.min_incl_x * src_bytes_per_pixel),
frame_rect.width() * src_bytes_per_pixel);
}
}
// The buffer is zeroed now, but this onStartIncrementalDecode call will
// almost certainly be followed by some onIncrementalDecode calls that can
// modify fPixelBuffer's contents. We set fPixbufZeroed to false so that
// the next onStartIncrementalDecode call will zero-initialize the buffer.
fPixbufZeroed = false;
fIncrDecDst = static_cast<uint8_t*>(dst);
fIncrDecReaderIOPosition = fIOBuffer.reader_io_position();
@ -886,8 +900,10 @@ std::unique_ptr<SkCodec> SkWuffsCodec_MakeFromStream(std::unique_ptr<SkStream> s
std::unique_ptr<uint8_t, decltype(&sk_free)> workbuf_ptr(
reinterpret_cast<uint8_t*>(workbuf_ptr_raw), &sk_free);
constexpr int pixbuf_sk_malloc_flags = SK_MALLOC_ZERO_INITIALIZE;
uint64_t pixbuf_len = imgcfg.pixcfg.pixbuf_len();
void* pixbuf_ptr_raw = pixbuf_len <= SIZE_MAX ? sk_malloc_canfail(pixbuf_len) : nullptr;
void* pixbuf_ptr_raw =
pixbuf_len <= SIZE_MAX ? sk_malloc_flags(pixbuf_len, pixbuf_sk_malloc_flags) : nullptr;
if (!pixbuf_ptr_raw) {
*result = SkCodec::kInternalError;
return nullptr;
@ -919,5 +935,6 @@ std::unique_ptr<SkCodec> SkWuffsCodec_MakeFromStream(std::unique_ptr<SkStream> s
*result = SkCodec::kSuccess;
return std::unique_ptr<SkCodec>(new SkWuffsCodec(
std::move(encodedInfo), std::move(stream), std::move(decoder), std::move(pixbuf_ptr),
std::move(workbuf_ptr), workbuf_len, imgcfg, pixbuf, iobuf));
(pixbuf_sk_malloc_flags & SK_MALLOC_ZERO_INITIALIZE) != 0, std::move(workbuf_ptr),
workbuf_len, imgcfg, pixbuf, iobuf));
}