Test code and result for MVTools ToPixels

CPU: Intel Xeon E3-1240v3 @3.40GHz

Test code:
#include <emmintrin.h>
#include <immintrin.h>
#include <avx2intrin.h>
#include <cstdint>
#include <random>
#include <cstdio>
#include <intrin.h>

#ifndef min
#define min(a,b)            (((a) < (b)) ? (a) : (b))
#endif

#include "../iaca-win64/iacaMarks.h"

#define avx 1
#define IACA_MARKS_OFF

typedef uint32_t PixelType2;
typedef uint16_t PixelType;

__inline __m256i _mm256_loadu2_m128i(__m128i *low, __m128i *high)
{
    return _mm256_inserti128_si256(_mm256_castsi128_si256(_mm_loadu_si128((__m128i*)low)),
                                                          _mm_loadu_si128((__m128i*)high),1);

}

void ToPixels_orig(uint8_t *pDst8, int nDstPitch, const uint8_t *pSrc8, int nSrcPitch, int nWidth, int nHeight, int bitsPerSample)
{
    int pixelMax = (1 << bitsPerSample) - 1;

    for (int h=0; h<nHeight; h++)
    {
        const PixelType2 *pSrc = (const PixelType2 *)pSrc8;
        PixelType *pDst = (PixelType *)pDst8;
        for (int i=0; i<nWidth; i++)
        {
            int a = (pSrc[i] + 16)>>5;
            if (sizeof(PixelType) == 1)
                pDst[i] = a | ((255-a) >> (sizeof(int)*8-1));
            else
                pDst[i] = min(pixelMax, a);
        }
        pDst8 += nDstPitch;
        pSrc8 += nSrcPitch;
    }
}

void ToPixels_AVX2_16bit(uint8_t *pDst8, int nDstPitch, const uint8_t *pSrc8, int nSrcPitch, int nWidth, int nHeight, int bitsPerSample)
{
    static __m256i const sixteen  = _mm256_set1_epi32(16);
    static __m128i const five     = _mm_set1_epi64x(5);
    for (int h=0; h<nHeight; h++)
    {
        const uint32_t *pSrc = (const uint32_t *)pSrc8;
        uint16_t *pDst = (uint16_t *)pDst8;

        nWidth_16 = (nWidth & ~15);
        for (int i = 0; i < nWidth_16; i += 16)
        {
            __m256i src_1 = _mm256_loadu2_m128i((__m128i* )(pSrc + i), (__m128i* )(pSrc + i + 8));
            __m256i src_2 = _mm256_loadu2_m128i((__m128i* )(pSrc + i + 4), (__m128i* )(pSrc + i + 12));

            __m256i a1 = _mm256_srl_epi32(_mm256_add_epi32(src_1, sixteen), five);
            __m256i a2 = _mm256_srl_epi32(_mm256_add_epi32(src_2, sixteen), five);
            _mm256_storeu_si256((__m256i* )(pDst + i), _mm256_packus_epi32(a1, a2));

        }

        for (int i = nWidth_16; nWidth_16 < nWidth; i++)
        {
            int a = (pSrc[i] + 16)>>5;
            pDst[i] = min(pixelMax, a);
        }
        pDst8 += nDstPitch;
        pSrc8 += nSrcPitch;
    }
}

void ToPixels_SSE2_16bit(uint8_t *pDst8, int nDstPitch, const uint8_t *pSrc8, int nSrcPitch, int nWidth, int nHeight, int bitsPerSample)
{
    static __m128i const sixteen  = _mm_set1_epi32(16);
    static __m128i const five     = _mm_set1_epi64x(5);
    for (int h=0; h<nHeight; h++)
    {
        const uint32_t *pSrc = (const uint32_t *)pSrc8;
        uint16_t *pDst = (uint16_t *)pDst8;

        nWidth_8 = (nWidth & ~7);
        for (int i = 0; i < nWidth_8; i += 8)
        {
            __m128i src_1 = _mm_lddqu_si128((__m128i* )(pSrc + i));
            __m128i src_2 = _mm_lddqu_si128((__m128i* )(pSrc + i + 4));

            __m128i a1 = _mm_srl_epi32(_mm_add_epi32(src_1, sixteen), five);
            __m128i a2 = _mm_srl_epi32(_mm_add_epi32(src_2, sixteen), five);
            _mm_storeu_si128((__m128i* )(pDst + i), _mm_packus_epi32(a1, a2));
        }

        for (int i = nWidth_8; nWidth_8 < nWidth; i++)
        {
            int a = (pSrc[i] + 16)>>5;
            pDst[i] = min(pixelMax, a);
        }
        pDst8 += nDstPitch;
        pSrc8 += nSrcPitch;
    }
}

uint64_t const MAX = 4294967296;
uint32_t const BATCH = 65536;
uint8_t const ITER = 10;

using namespace std;

int main()
{
    uint32_t *src = new uint32_t[BATCH];
    uint16_t *dst = new uint16_t[BATCH];
    uint16_t *sse = new uint16_t[BATCH];
    uint64_t tot_c = 0, tot_avx = 0, tot_sse = 0;
    uint64_t start, end;
    for(uint8_t j = 0; j < ITER; j++)
    {
        for(uint32_t iter = 0; iter < BATCH; iter++)
        {
            for(uint64_t i = 0; i < BATCH; i++)
                src[i] = BATCH * iter + i;

            start = __rdtsc();
            ToPixels_orig((uint8_t*)dst, BATCH, (uint8_t*)src, BATCH, BATCH, 1, 16);
            end = __rdtsc();
            tot_c += end - start;

            start = __rdtsc();
            ToPixels_SSE2_16bit((uint8_t*)sse, BATCH, (uint8_t*)src, BATCH, BATCH, 1, 16);
            end = __rdtsc();
            tot_sse += end - start;

            start = __rdtsc();
            ToPixels_AVX2_16bit((uint8_t*)sse, BATCH, (uint8_t*)src, BATCH, BATCH, 1, 16);
            end = __rdtsc();
            tot_avx += end - start;

        }

        printf("cicli c  : %20llu\n"
               "cicli avx: %20llu\n"
               "cicli sse: %20llu\n"
               "diffenza c/avx: %f\n"
               "diffenza c/sse: %f\n"
               "diffenza sse/avx: %f\n", tot_c, tot_avx, tot_sse, (float)tot_c/(float)tot_avx, (float)tot_c/(float)tot_sse, (float)tot_sse/(float)tot_avx);


    }
        system("pause");

    return 0;
}

 -O2 -march=core-avx2
 cicli c  :          16069028936
cicli avx:           3479067731
cicli sse:           3952420122
diffenza c/avx: 4.618774
diffenza c/sse: 4.065618
diffenza sse/avx: 1.136057
cicli c  :          36326105778
cicli avx:           7875570050
cicli sse:           8945499109
diffenza c/avx: 4.612505
diffenza c/sse: 4.060825
diffenza sse/avx: 1.135854
cicli c  :          53213062764
cicli avx:          11534067363
cicli sse:          13100670525
diffenza c/avx: 4.613555
diffenza c/sse: 4.061858
diffenza sse/avx: 1.135824
cicli c  :          67941010573
cicli avx:          14727013850
cicli sse:          16725254304
diffenza c/avx: 4.613360
diffenza c/sse: 4.062181
diffenza sse/avx: 1.135685
cicli c  :          89191667408
cicli avx:          19335612709
cicli sse:          21957883495
diffenza c/avx: 4.612818
diffenza c/sse: 4.061943
diffenza sse/avx: 1.135619
cicli c  :         109229600089
cicli avx:          23575137811
cicli sse:          26813487597
diffenza c/avx: 4.633254
diffenza c/sse: 4.073681
diffenza sse/avx: 1.137363
cicli c  :         122392466376
cicli avx:          26355151378
cicli sse:          29993017323
diffenza c/avx: 4.643968
diffenza c/sse: 4.080699
diffenza sse/avx: 1.138032
cicli c  :         139711839407
cicli avx:          30032840475
cicli sse:          34210571303
diffenza c/avx: 4.651969
diffenza c/sse: 4.083879
diffenza sse/avx: 1.139105
cicli c  :         154549375786
cicli avx:          33205606096
cicli sse:          37834240435
diffenza c/avx: 4.654315
diffenza c/sse: 4.084908
diffenza sse/avx: 1.139393
cicli c  :         167509109185
cicli avx:          36013172486
cicli sse:          41023592505
diffenza c/avx: 4.651329
diffenza c/sse: 4.083239
diffenza sse/avx: 1.139127

-O3 -march=core-avx2
cicli c  :           6871242081
cicli avx:           5664816544
cicli sse:           6254182296
diffenza c/avx: 1.212968
diffenza c/sse: 1.098664
diffenza sse/avx: 1.104040
cicli c  :          12683725691
cicli avx:          10469204071
cicli sse:          11560038037
diffenza c/avx: 1.211527
diffenza c/sse: 1.097204
diffenza sse/avx: 1.104195
cicli c  :          17847899606
cicli avx:          14773516038
cicli sse:          16374322201
diffenza c/avx: 1.208101
diffenza c/sse: 1.089993
diffenza sse/avx: 1.108356
cicli c  :          23062613551
cicli avx:          19120545569
cicli sse:          21234215418
diffenza c/avx: 1.206169
diffenza c/sse: 1.086106
diffenza sse/avx: 1.110544
cicli c  :          27206401088
cicli avx:          22573441790
cicli sse:          25082508148
diffenza c/avx: 1.205239
diffenza c/sse: 1.084676
diffenza sse/avx: 1.111151
cicli c  :          31937676651
cicli avx:          26493333877
cicli sse:          29447055320
diffenza c/avx: 1.205499
diffenza c/sse: 1.084580
diffenza sse/avx: 1.111489
cicli c  :          37115015173
cicli avx:          30810575815
cicli sse:          34294225401
diffenza c/avx: 1.204619
diffenza c/sse: 1.082253
diffenza sse/avx: 1.113067
cicli c  :          41459165763
cicli avx:          34391557986
cicli sse:          38270611514
diffenza c/avx: 1.205504
diffenza c/sse: 1.083316
diffenza sse/avx: 1.112791
cicli c  :          47518820008
cicli avx:          39417068102
cicli sse:          43835101728
diffenza c/avx: 1.205539
diffenza c/sse: 1.084036
diffenza sse/avx: 1.112084
cicli c  :          53266037373
cicli avx:          44166766473
cicli sse:          49077206995
diffenza c/avx: 1.206021
diffenza c/sse: 1.085352
diffenza sse/avx: 1.111180