From 2d61ed7fc6c56de61fd347624b1fd40496ac1b4f Mon Sep 17 00:00:00 2001
From: Ilya Kurdyukov <59548320+ilyakurdyukov@users.noreply.github.com>
Date: Tue, 16 May 2023 17:19:05 +0700
Subject: [PATCH] ~7% faster Q5_1 AVX2 code

X is always positive (range 0..31) in ggml_vec_dot_q5_1_q8_1(), so there's no need for two _mm256_sign_epi8().
---
 ggml.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/ggml.c b/ggml.c
index 4311ce7cf..fad137ad6 100644
--- a/ggml.c
+++ b/ggml.c
@@ -543,12 +543,7 @@ static inline __m256 sum_i16_pairs_float(const __m256i x) {
     return _mm256_cvtepi32_ps(summed_pairs);
 }
 
-// multiply int8_t, add results pairwise twice and return as float vector
-static inline __m256 mul_sum_i8_pairs_float(const __m256i x, const __m256i y) {
-    // Get absolute values of x vectors
-    const __m256i ax = _mm256_sign_epi8(x, x);
-    // Sign the values of the y vectors
-    const __m256i sy = _mm256_sign_epi8(y, x);
+static inline __m256 mul_sum_us8_pairs_float(const __m256i ax, const __m256i sy) {
 #if __AVXVNNI__
     const __m256i zero = _mm256_setzero_si256();
     const __m256i summed_pairs = _mm256_dpbusd_epi32(zero, ax, sy);
@@ -560,6 +555,15 @@ static inline __m256 mul_sum_i8_pairs_float(const __m256i x, const __m256i y) {
 #endif
 }
 
+// multiply int8_t, add results pairwise twice and return as float vector
+static inline __m256 mul_sum_i8_pairs_float(const __m256i x, const __m256i y) {
+    // Get absolute values of x vectors
+    const __m256i ax = _mm256_sign_epi8(x, x);
+    // Sign the values of the y vectors
+    const __m256i sy = _mm256_sign_epi8(y, x);
+    return mul_sum_us8_pairs_float(ax, sy);
+}
+
 static inline __m128i packNibbles( __m256i bytes )
 {
     // Move bits within 16-bit lanes from 0000_abcd_0000_efgh into 0000_0000_abcd_efgh
@@ -2906,7 +2910,7 @@ static void ggml_vec_dot_q5_1_q8_1(const int n, float * restrict s, const void *
         const __m256 dy = _mm256_broadcast_ss(&y[i].d);
         const __m256i by = _mm256_loadu_si256((const __m256i *)y[i].qs);
 
-        const __m256 q = mul_sum_i8_pairs_float(bx, by);
+        const __m256 q = mul_sum_us8_pairs_float(bx, by);
 
         acc = _mm256_fmadd_ps(q, _mm256_mul_ps(dx, dy), acc);
     }
@@ -2940,7 +2944,7 @@ static void ggml_vec_dot_q5_1_q8_1(const int n, float * restrict s, const void *
         const __m256 dy = _mm256_broadcast_ss(&y[i].d);
         const __m256i by = _mm256_loadu_si256((const __m256i *)y[i].qs);
 
-        const __m256 q = mul_sum_i8_pairs_float(bx, by);
+        const __m256 q = mul_sum_us8_pairs_float(bx, by);
 
         acc = _mm256_add_ps(_mm256_mul_ps(q, _mm256_mul_ps(dx, dy)), acc);
     }