Add AVX2 version of ggml_vec_dot_q4_1

This commit is contained in:
Matvey Soloviev 2023-03-14 19:37:58 +01:00
parent 9b4a15b17d
commit 561733cafa

72
ggml.c
View file

@ -1595,7 +1595,77 @@ inline static void ggml_vec_dot_q4_1(const int n, float * restrict s, const void
float sumf = 0.0;
#if 1
#if defined(__AVX2__)
#if QK == 32
// Initialize accumulator with zeros
__m256 acc = _mm256_setzero_ps();
// Accumulator for constant offsets
float acc_offset = 0.0f;
// Main loop
for (int i = 0; i < nb; ++i) {
const float * m0 = (const float *) (pm0 + i);
const float * m1 = (const float *) (pm1 + i);
const float * d0 = (const float *) (pd0 + i);
const float * d1 = (const float *) (pd1 + i);
const uint8_t * restrict p0 = pb0 + i*QK/2;
const uint8_t * restrict p1 = pb1 + i*QK/2;
// Compute combined scale for the block
const __m256 scale_01 = _mm256_mul_ps( _mm256_broadcast_ss( d0 ), _mm256_broadcast_ss( d1 ) );
// Compute cross scales for the block
const __m256 scale_0 = _mm256_mul_ps( _mm256_broadcast_ss( d0 ), _mm256_broadcast_ss( m1 ) );
const __m256 scale_1 = _mm256_mul_ps( _mm256_broadcast_ss( m0 ), _mm256_broadcast_ss( d1 ) );
// Load 16 bytes, and unpack 4 bit fields into bytes, making 32 bytes
__m256i bx = bytesFromNibbles( p0 );
__m256i by = bytesFromNibbles( p1 );
// Now we have a vector with bytes in [ 0 .. 15 ] interval.
// Sign-extend first 16 signed bytes into int16_t
__m256i x16 = _mm256_cvtepi8_epi16( _mm256_castsi256_si128( bx ) );
__m256i y16 = _mm256_cvtepi8_epi16( _mm256_castsi256_si128( by ) );
// Compute products of int16_t integers, add pairwise
__m256i i32 = _mm256_madd_epi16( x16, y16 );
// Sign-extend last 16 signed bytes into int16_t vectors
__m256i x16_h = _mm256_cvtepi8_epi16( _mm256_extracti128_si256( bx, 1 ) );
__m256i y16_h = _mm256_cvtepi8_epi16( _mm256_extracti128_si256( by, 1 ) );
// Accumulate products of int16_t integers
i32 = _mm256_add_epi32( i32, _mm256_madd_epi16( x16_h, y16_h ) );
// compute sums of unsigned bytes in bx, by in blocks of 8.
// This results in a layout like S100 0000 S200 0000 S300 0000 S400 0000,
// so if we then cast to 8 singles, we get 8 floats like [ s0_7, 0.0, s8_15, 0.0, s16_23, 0.0, s24_31, 0.0 ]
__m256 xsum = _mm256_cvtepi32_ps( _mm256_sad_epu8( bx, _mm256_setzero_si256() ) );
__m256 ysum = _mm256_cvtepi32_ps( _mm256_sad_epu8( by, _mm256_setzero_si256() ) );
// Convert int32_t to float
__m256 p = _mm256_cvtepi32_ps( i32 );
// Apply the scale, and accumulate
// acc += d0*d1*x*y + d0*m1*x + d1*m0*y
acc = _mm256_fmadd_ps( scale_01, p, acc );
acc = _mm256_fmadd_ps( scale_0, xsum, acc );
acc = _mm256_fmadd_ps( scale_1, ysum, acc );
// acc_offset += m0*m1 (for each entry in the block)
acc_offset += (*m0)*(*m1)*QK;
}
// Return horizontal sum of the acc vector
__m128 res = _mm256_extractf128_ps( acc, 1 );
res = _mm_add_ps( res, _mm256_castps256_ps128( acc ) );
res = _mm_add_ps( res, _mm_movehl_ps( res, res ) );
res = _mm_add_ss( res, _mm_movehdup_ps( res ) );
sumf = _mm_cvtss_f32( res ) + acc_offset;
#else
#error "not implemented for QK"
#endif
#else
// scalar
for (int i = 0; i < nb; i++) {
const float m0 = pm0[i];