gcc/testsuite/gcc.target/i386/pr105493.c

/* { dg-do compile { target { ! ia32 } } } */
/* { dg-options "-Ofast -march=icelake-server -fdump-tree-slp-details" } */

typedef unsigned char uint8_t;
typedef unsigned int uint32_t;
typedef unsigned short uint16_t;

static inline
uint32_t abs2 ( uint32_t a )
{
    uint32_t s = ((a>>15)&0x10001)*0xffff;
    return (a+s)^s;
}

#define HADAMARD4(d0, d1, d2, d3, s0, s1, s2, s3) {\
    int t0 = s0 + s1;\
    int t1 = s0 - s1;\
    int t2 = s2 + s3;\
    int t3 = s2 - s3;\
    d0 = t0 + t2;\
    d2 = t0 - t2;\
    d1 = t1 + t3;\
    d3 = t1 - t3;\
}

int
foo ( uint8_t *pix1, int i_pix1, uint8_t *pix2, int i_pix2 )
{
    uint32_t tmp[4][4];
    uint32_t a0, a1, a2, a3;
    int sum = 0;
    for( int i = 0; i < 4; i++, pix1 += i_pix1, pix2 += i_pix2 )
    {
        a0 = (pix1[0] - pix2[0]) + ((pix1[4] - pix2[4]) << 16);
        a1 = (pix1[1] - pix2[1]) + ((pix1[5] - pix2[5]) << 16);
        a2 = (pix1[2] - pix2[2]) + ((pix1[6] - pix2[6]) << 16);
        a3 = (pix1[3] - pix2[3]) + ((pix1[7] - pix2[7]) << 16);
        HADAMARD4( tmp[i][0], tmp[i][1], tmp[i][2], tmp[i][3], a0,a1,a2,a3 );
    }
    for( int i = 0; i < 4; i++ )
    {
        HADAMARD4( a0, a1, a2, a3, tmp[0][i], tmp[1][i], tmp[2][i], tmp[3][i] );
        sum += abs2(a0) + abs2(a1) + abs2(a2) + abs2(a3);
    }
    return (((uint16_t)sum) + ((uint32_t)sum>>16)) >> 1;
}


/* The first loop should be vectorized, which will eliminate redundant stores
   and loads.  */
/* { dg-final { scan-tree-dump-times "  MEM <vector\\\(4\\\) unsigned int> \\\[\[\^\]\]\*\\\] = " 4 "slp1" } } */