AuroraMiddleware/skia2
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

add alternate x-lerp using vpmaddubsw

Browse Source 
This looks like a _very_ minor perf and code size win.

Change-Id: Ieb9d07eb056f66fc90b0e3c36835cc05329ff7b6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/244920
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
This commit is contained in:
Mike Klein 2019-09-27 12:58:01 -05:00 committed by Skia Commit-Bot
parent 1e9112fbb4
commit ac353cbbfc
1 changed files with 35 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
src/opts/SkBitmapProcState_opts.h
View File

@ -82,6 +82,40 @@ static void decode_packed_coordinates_and_weight(U32 packed, Out* v0, Out* v1, O
skvx::Vec<8,uint32_t> tl = gather(row0, x0), tr = gather(row0, x1),
bl = gather(row1, x0), br = gather(row1, x1);
#if 1
// We'll use _mm256_maddubs_epi16() to lerp much like in the SSSE3 code.
auto lerp_x = [&](skvx::Vec<8,uint32_t> L, skvx::Vec<8,uint32_t> R) {
__m256i l = skvx::bit_pun<__m256i>(L),
r = skvx::bit_pun<__m256i>(R),
wr = skvx::bit_pun<__m256i>(wx),
wl = _mm256_sub_epi8(_mm256_set1_epi8(16), wr);
// Interlace l,r bytewise and line them up with their weights, then lerp.
__m256i lo = _mm256_maddubs_epi16(_mm256_unpacklo_epi8( l, r),
_mm256_unpacklo_epi8(wl,wr));
__m256i hi = _mm256_maddubs_epi16(_mm256_unpackhi_epi8( l, r),
_mm256_unpackhi_epi8(wl,wr));
// Those _mm256_unpack??_epi8() calls left us in a bit of an odd order:
//
// if l = a b c d | e f g h
// and r = A B C D | E F G H
//
// then lo = a A b B | e E f F (low half of each input)
// and hi = c C d D | g G h H (high half of each input)
//
// To get everything back in original order we need to transpose that.
__m256i abcd = _mm256_permute2x128_si256(lo, hi, 0x20),
efgh = _mm256_permute2x128_si256(lo, hi, 0x31);
return skvx::join(skvx::bit_pun<skvx::Vec<16,uint16_t>>(abcd),
skvx::bit_pun<skvx::Vec<16,uint16_t>>(efgh));
};
skvx::Vec<32, uint16_t> top = lerp_x(tl, tr),
bot = lerp_x(bl, br),
sum = 16*top + (bot-top)*wy;
#else
// Treat 32-bit pixels as 4 8-bit values, and expand to 16-bit for room to multiply.
auto to_16x4 = [](auto v) -> skvx::Vec<32, uint16_t> {
return skvx::cast<uint16_t>(skvx::bit_pun<skvx::Vec<32, uint8_t>>(v));
@ -100,6 +134,7 @@ static void decode_packed_coordinates_and_weight(U32 packed, Out* v0, Out* v1, O
};
skvx::Vec<32, uint16_t> sum = lerp(lerp(to_16x4(tl), to_16x4(bl), wy),
lerp(to_16x4(tr), to_16x4(br), wy), to_16x4(wx));
#endif
// Get back to [0,255] by dividing by maximum weight 16x16 = 256.
sum >>= 8;