Improve latency of FTransform2.

Benchmarks from vrabaud@:
8BIT/GRAY                corpus speed: faster: -4.3 % , corpus size: unchanged
skal/sources_png_skal    corpus speed: faster: -5.2 % , corpus size: unchanged
images/png_rgb           corpus speed: faster: -5.1 % , corpus size: unchanged
images/lpcb              corpus speed: unchanged, corpus size: unchanged
images/png_big           corpus speed: faster: -1.7 % , corpus size: unchanged
images/png_doc           corpus speed: unchanged, corpus size: unchanged
images/png_1bit          corpus speed: faster: -1.2 % , corpus size: unchanged
images/jpeg_small        corpus speed: unchanged, corpus size: unchanged
images/icip_core1        corpus speed: unchanged, corpus size: unchanged
images/png_gray          corpus speed: faster: -2.5 % , corpus size: unchanged
images/jpeg_high_quality corpus speed: faster: -4.0 % , corpus size: unchanged
images/jpeg              corpus speed: faster: -2.3 % , corpus size: unchanged
images/png_translucent   corpus speed: faster: -2.8 % , corpus size: unchanged
images/gif               corpus speed: faster: -1.4 % , corpus size: unchanged
images/png_opaque        corpus speed: faster: -2.8 % , corpus size: unchanged
images/png_rgb_opaque    corpus speed: unchanged, corpus size: unchanged
images/png_indexed       corpus speed: faster: -2.0 % , corpus size: unchanged
images/all               corpus speed: faster: -1.5 % , corpus size: unchanged
images/png_small         corpus speed: unchanged, corpus size: unchanged
images/png               corpus speed: unchanged, corpus size: unchanged
images/gif_still         corpus speed: faster: -1.6 % , corpus size: unchanged

Change-Id: I69fe11baa188c5d32cbc77a84b8c0deae13d792b
This commit is contained in:
Owen Rodley 2016-11-22 22:36:08 +00:00 committed by James Zern
parent 16951b1905
commit 67748b41db

View File

@ -251,25 +251,11 @@ static void FTransformPass2(const __m128i* const v01, const __m128i* const v32,
const __m128i k51000 = _mm_set1_epi32(51000);
// Same operations are done on the (0,3) and (1,2) pairs.
// a0 = v0 + v3
// a1 = v1 + v2
// a3 = v0 - v3
// a2 = v1 - v2
const __m128i a01 = _mm_add_epi16(*v01, *v32);
const __m128i a32 = _mm_sub_epi16(*v01, *v32);
const __m128i a11 = _mm_unpackhi_epi64(a01, a01);
const __m128i a22 = _mm_unpackhi_epi64(a32, a32);
const __m128i a01_plus_7 = _mm_add_epi16(a01, seven);
// d0 = (a0 + a1 + 7) >> 4;
// d2 = (a0 - a1 + 7) >> 4;
const __m128i c0 = _mm_add_epi16(a01_plus_7, a11);
const __m128i c2 = _mm_sub_epi16(a01_plus_7, a11);
const __m128i d0 = _mm_srai_epi16(c0, 4);
const __m128i d2 = _mm_srai_epi16(c2, 4);
// f1 = ((b3 * 5352 + b2 * 2217 + 12000) >> 16)
// f3 = ((b3 * 2217 - b2 * 5352 + 51000) >> 16)
const __m128i b23 = _mm_unpacklo_epi16(a22, a32);
const __m128i c1 = _mm_madd_epi16(b23, k5352_2217);
const __m128i c3 = _mm_madd_epi16(b23, k2217_5352);
@ -277,14 +263,28 @@ static void FTransformPass2(const __m128i* const v01, const __m128i* const v32,
const __m128i d3 = _mm_add_epi32(c3, k51000);
const __m128i e1 = _mm_srai_epi32(d1, 16);
const __m128i e3 = _mm_srai_epi32(d3, 16);
// f1 = ((b3 * 5352 + b2 * 2217 + 12000) >> 16)
// f3 = ((b3 * 2217 - b2 * 5352 + 51000) >> 16)
const __m128i f1 = _mm_packs_epi32(e1, e1);
const __m128i f3 = _mm_packs_epi32(e3, e3);
// f1 = f1 + (a3 != 0);
// g1 = f1 + (a3 != 0);
// The compare will return (0xffff, 0) for (==0, !=0). To turn that into the
// desired (0, 1), we add one earlier through k12000_plus_one.
// -> f1 = f1 + 1 - (a3 == 0)
// -> g1 = f1 + 1 - (a3 == 0)
const __m128i g1 = _mm_add_epi16(f1, _mm_cmpeq_epi16(a32, zero));
// a0 = v0 + v3
// a1 = v1 + v2
const __m128i a01 = _mm_add_epi16(*v01, *v32);
const __m128i a01_plus_7 = _mm_add_epi16(a01, seven);
const __m128i a11 = _mm_unpackhi_epi64(a01, a01);
const __m128i c0 = _mm_add_epi16(a01_plus_7, a11);
const __m128i c2 = _mm_sub_epi16(a01_plus_7, a11);
// d0 = (a0 + a1 + 7) >> 4;
// d2 = (a0 - a1 + 7) >> 4;
const __m128i d0 = _mm_srai_epi16(c0, 4);
const __m128i d2 = _mm_srai_epi16(c2, 4);
const __m128i d0_g1 = _mm_unpacklo_epi64(d0, g1);
const __m128i d2_f3 = _mm_unpacklo_epi64(d2, f3);
_mm_storeu_si128((__m128i*)&out[0], d0_g1);