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Flush to zero when loading f16 with sse2/sse4.1.

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The multiply by 0x77800000 is quite slow when the input is denormalized.
We don't mind flushing those values (in the range of 1e-5) to zero.

Implement portable load_f16() / store_f16() too.

Change-Id: I125cff1c79ca71d9abe22ac7877136d86707cb56
Reviewed-on: https://skia-review.googlesource.com/8467
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
This commit is contained in:
Mike Klein 2017-02-16 06:21:54 -05:00
parent 8729e5bbf7
commit fa64774820
4 changed files with 48 additions and 13 deletions
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2
src/jumper/SkJumper.cpp
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@ -18,7 +18,7 @@ static const SkJumper_constants kConstants = {
{0.0f, 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f, 7.0f},
0.0025f, 0.6975f, 0.3000f, 1/12.92f, 0.055f, // from_srgb
12.46f, 0.411192f, 0.689206f, -0.0988f, 0.0043f, // to_srgb
0x77800000, 0x07800000, // fp16 <-> fp32
0x77800000, 0x07800000, 0x04000400, // fp16 <-> fp32
};
using JumperStage = void(size_t, void**, const SkJumper_constants*);

1
src/jumper/SkJumper.h
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@ -46,6 +46,7 @@ struct SkJumper_constants {
// fp16 <-> fp32
uint32_t _0x77800000;
uint32_t _0x07800000;
uint32_t _0x04000400;
};
#endif//SkJumper_DEFINED

30
src/jumper/SkJumper_generated.h
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@ -1953,12 +1953,19 @@ static const unsigned char sse41_sk_load_f16[] = {
0x48,0x8b,0x00, // mov (%rax),%rax
0xf3,0x0f,0x6f,0x04,0xf8, // movdqu (%rax,%rdi,8),%xmm0
0xf3,0x0f,0x6f,0x4c,0xf8,0x10, // movdqu 0x10(%rax,%rdi,8),%xmm1
0x66,0x0f,0x6f,0xd8, // movdqa %xmm0,%xmm3
0x66,0x0f,0x61,0xd9, // punpcklwd %xmm1,%xmm3
0x66,0x0f,0x6f,0xd0, // movdqa %xmm0,%xmm2
0x66,0x0f,0x61,0xd1, // punpcklwd %xmm1,%xmm2
0x66,0x0f,0x69,0xc1, // punpckhwd %xmm1,%xmm0
0x66,0x44,0x0f,0x6f,0xc2, // movdqa %xmm2,%xmm8
0x66,0x44,0x0f,0x61,0xc0, // punpcklwd %xmm0,%xmm8
0x66,0x0f,0x69,0xd0, // punpckhwd %xmm0,%xmm2
0x66,0x0f,0x6e,0x42,0x64, // movd 0x64(%rdx),%xmm0
0x66,0x0f,0x70,0xd8,0x00, // pshufd $0x0,%xmm0,%xmm3
0x66,0x0f,0x6f,0xcb, // movdqa %xmm3,%xmm1
0x66,0x0f,0x61,0xc8, // punpcklwd %xmm0,%xmm1
0x66,0x0f,0x69,0xd8, // punpckhwd %xmm0,%xmm3
0x66,0x41,0x0f,0x65,0xc8, // pcmpgtw %xmm8,%xmm1
0x66,0x41,0x0f,0xdf,0xc8, // pandn %xmm8,%xmm1
0x66,0x0f,0x65,0xda, // pcmpgtw %xmm2,%xmm3
0x66,0x0f,0xdf,0xda, // pandn %xmm2,%xmm3
0x66,0x0f,0x38,0x33,0xc1, // pmovzxwd %xmm1,%xmm0
0x66,0x0f,0x72,0xf0,0x0d, // pslld $0xd,%xmm0
0x66,0x0f,0x6e,0x52,0x5c, // movd 0x5c(%rdx),%xmm2
@ -2586,12 +2593,19 @@ static const unsigned char sse2_sk_load_f16[] = {
0x48,0x8b,0x00, // mov (%rax),%rax
0xf3,0x0f,0x6f,0x04,0xf8, // movdqu (%rax,%rdi,8),%xmm0
0xf3,0x0f,0x6f,0x4c,0xf8,0x10, // movdqu 0x10(%rax,%rdi,8),%xmm1
0x66,0x0f,0x6f,0xd8, // movdqa %xmm0,%xmm3
0x66,0x0f,0x61,0xd9, // punpcklwd %xmm1,%xmm3
0x66,0x0f,0x6f,0xd0, // movdqa %xmm0,%xmm2
0x66,0x0f,0x61,0xd1, // punpcklwd %xmm1,%xmm2
0x66,0x0f,0x69,0xc1, // punpckhwd %xmm1,%xmm0
0x66,0x44,0x0f,0x6f,0xc2, // movdqa %xmm2,%xmm8
0x66,0x44,0x0f,0x61,0xc0, // punpcklwd %xmm0,%xmm8
0x66,0x0f,0x69,0xd0, // punpckhwd %xmm0,%xmm2
0x66,0x0f,0x6e,0x42,0x64, // movd 0x64(%rdx),%xmm0
0x66,0x0f,0x70,0xd8,0x00, // pshufd $0x0,%xmm0,%xmm3
0x66,0x0f,0x6f,0xcb, // movdqa %xmm3,%xmm1
0x66,0x0f,0x61,0xc8, // punpcklwd %xmm0,%xmm1
0x66,0x0f,0x69,0xd8, // punpckhwd %xmm0,%xmm3
0x66,0x41,0x0f,0x65,0xc8, // pcmpgtw %xmm8,%xmm1
0x66,0x41,0x0f,0xdf,0xc8, // pandn %xmm8,%xmm1
0x66,0x0f,0x65,0xda, // pcmpgtw %xmm2,%xmm3
0x66,0x0f,0xdf,0xda, // pandn %xmm2,%xmm3
0x66,0x45,0x0f,0xef,0xc0, // pxor %xmm8,%xmm8
0x66,0x0f,0x6f,0xc1, // movdqa %xmm1,%xmm0
0x66,0x41,0x0f,0x61,0xc0, // punpcklwd %xmm8,%xmm0

28
src/jumper/SkJumper_stages.cpp
View File

@ -402,8 +402,16 @@ STAGE(load_f16) {
auto ptr = *(const uint64_t**)ctx + x;
#if !defined(JUMPER)
// TODO:
(void)ptr;
auto half_to_float = [&](int16_t h) {
if (h < 0x0400) { h = 0; } // Flush denorm and negative to zero.
return bit_cast<F>(h << 13) // Line up the mantissa,
* bit_cast<F>(U32(k->_0x77800000)); // then fix up the exponent.
};
auto rgba = (const int16_t*)ptr;
r = half_to_float(rgba[0]);
g = half_to_float(rgba[1]);
b = half_to_float(rgba[2]);
a = half_to_float(rgba[3]);
#elif defined(__aarch64__)
auto halfs = vld4_f16((const float16_t*)ptr);
r = vcvt_f32_f16(halfs.val[0]);
@ -448,6 +456,11 @@ STAGE(load_f16) {
auto rg = _mm_unpacklo_epi16(_02, _13), // r0 r1 r2 r3 g0 g1 g2 g3
ba = _mm_unpackhi_epi16(_02, _13); // b0 b1 b2 b3 a0 a1 a2 a3
// half_to_float() slows down ~10x for denorm inputs, so we flush them to zero.
// With a signed comparison this conveniently also flushes negative half floats to zero.
rg = _mm_andnot_si128(_mm_cmplt_epi16(rg, U32(k->_0x04000400)), rg);
ba = _mm_andnot_si128(_mm_cmplt_epi16(ba, U32(k->_0x04000400)), ba);
auto half_to_float = [&](U32 h) {
return bit_cast<F>(h << 13) // Line up the mantissa,
* bit_cast<F>(U32(k->_0x77800000)); // then fix up the exponent.
@ -464,8 +477,15 @@ STAGE(store_f16) {
auto ptr = *(uint64_t**)ctx + x;
#if !defined(JUMPER)
// TODO:
(void)ptr;
auto float_to_half = [&](F f) {
return bit_cast<U32>(f * bit_cast<F>(U32(k->_0x07800000))) // Fix up the exponent,
>> 13; // then line up the mantissa.
};
auto rgba = (int16_t*)ptr;
rgba[0] = float_to_half(r);
rgba[1] = float_to_half(g);
rgba[2] = float_to_half(b);
rgba[3] = float_to_half(a);
#elif defined(__aarch64__)
float16x4x4_t halfs = {{
vcvt_f16_f32(r),