Add initial AVX512 support for dot product on Linux

* Update Makefile to detect AVX512 support and add compiler flags if it's available
 * Based on existing AVX2 implementation, dot product on one 32-value block of 4-bit quantized ints at a time
 * Perform 8 bit -> 16 bit sign extension and multiply+add on 32 values at time instead of 16
 * Use built-in AVX512 horizontal reduce add to get sum at the end
 * Manual unrolling on inner dot product loop to reduce loop counter overhead

Makefile

@@ -95,6 +95,38 @@ ifeq ($(UNAME_M),$(filter $(UNAME_M),x86_64 i686))
 		ifneq (,$(findstring sse3,$(SSE3_M)))
 			CFLAGS += -msse3
 		endif
+		AVX512F_M := $(shell grep "avx512f " /proc/cpuinfo)
+		ifneq (,$(findstring avx512f,$(AVX512F_M)))
+			CFLAGS += -mavx512f
+		endif
+		AVX512BW_M := $(shell grep "avx512bw " /proc/cpuinfo)
+		ifneq (,$(findstring avx512bw,$(AVX512BW_M)))
+			CFLAGS += -mavx512bw
+		endif
+		AVX512DQ_M := $(shell grep "avx512dq " /proc/cpuinfo)
+		ifneq (,$(findstring avx512dq,$(AVX512DQ_M)))
+			CFLAGS += -mavx512dq
+		endif
+		AVX512VL_M := $(shell grep "avx512vl " /proc/cpuinfo)
+		ifneq (,$(findstring avx512vl,$(AVX512VL_M)))
+			CFLAGS += -mavx512vl
+		endif
+		AVX512CD_M := $(shell grep "avx512cd " /proc/cpuinfo)
+		ifneq (,$(findstring avx512cd,$(AVX512CD_M)))
+			CFLAGS += -mavx512cd
+		endif
+		AVX512ER_M := $(shell grep "avx512er " /proc/cpuinfo)
+		ifneq (,$(findstring avx512er,$(AVX512ER_M)))
+			CFLAGS += -mavx512er
+		endif
+		AVX512IFMA_M := $(shell grep "avx512ifma " /proc/cpuinfo)
+		ifneq (,$(findstring avx512ifma,$(AVX512IFMA_M)))
+			CFLAGS += -mavx512ifma
+		endif
+		AVX512PF_M := $(shell grep "avx512pf " /proc/cpuinfo)
+		ifneq (,$(findstring avx512pf,$(AVX512PF_M)))
+			CFLAGS += -mavx512pf
+		endif
 	else ifeq ($(UNAME_S),Haiku)
 		AVX1_M := $(shell sysinfo -cpu | grep "AVX ")
 		ifneq (,$(findstring avx,$(AVX1_M)))

ggml.c

@@ -1417,6 +1417,93 @@ inline static void ggml_vec_dot_q4_0(const int n, float * restrict s, const void
 #else
 #error "not implemented for QK"
 #endif
+#elif defined(__AVX512F__)
+inline __m256i bytesFromNibbles( const uint8_t* rsi ){
+    // Load 16 bytes from memory
+    __m128i tmp = _mm_loadu_si128( ( const __m128i* )rsi );
+
+    // Expand bytes into uint16_t values
+    __m256i bytes = _mm256_cvtepu8_epi16( tmp );
+
+    // Unpack values into individual bytes
+    const __m256i lowMask = _mm256_set1_epi8( 0xF );
+    __m256i high = _mm256_andnot_si256( lowMask, bytes );
+    __m256i low = _mm256_and_si256( lowMask, bytes );
+    high = _mm256_slli_epi16( high, 4 );
+    bytes = _mm256_or_si256( low, high );
+    return bytes;
+}
+
+inline __m512 process_one_block(
+    __m512 acc,
+    const uint8_t * pd0,
+    const uint8_t * pd1,
+    const uint8_t * pb0,
+    const uint8_t * pb1,
+    int i
+) {
+    const float * d0_0 = (const float *) (pd0 + i*bs);
+    const float * d1_0 = (const float *) (pd1 + i*bs);
+
+    const uint8_t * restrict p0 = pb0 + (i+0)*bs;
+    const uint8_t * restrict p1 = pb1 + (i+0)*bs;
+
+    // Compute combined scale for the block
+    float scaleScalar = d0_0[0] * d1_0[0];
+    __m512 scale = _mm512_set1_ps( scaleScalar );
+
+    __m256i bx = bytesFromNibbles( p0 );
+    __m256i by = bytesFromNibbles( p1 );
+
+    // Now we have a vector with bytes in [ 0 .. 15 ] interval. Offset them into [ -8 .. +7 ] interval.
+    const __m256i off = _mm256_set1_epi8( 8 );
+    bx = _mm256_sub_epi8( bx, off );
+    by = _mm256_sub_epi8( by, off );
+
+    // Sign-extend 16 signed bytes into int16_t
+    __m512i x32 = _mm512_cvtepi8_epi16( bx );
+    __m512i y32 = _mm512_cvtepi8_epi16( by );
+    // Compute products of int16_t integers, add pairwise
+    __m512i i64 = _mm512_madd_epi16( x32, y32 );
+
+    // Convert int32_t to float
+    __m512 p = _mm512_cvtepi32_ps( i64 );
+    // Apply the scale, and accumulate
+    return _mm512_fmadd_ps( scale, p, acc );
+}
+
+#if QK == 32
+    // Initialize accumulator with zeros
+    __m512 acc0 = _mm512_setzero_ps();
+    __m512 acc1 = _mm512_setzero_ps();
+
+    const int superblock_size = 8;
+    const int superblock_count = nb / superblock_size;
+    const int remainder = nb % superblock_size;
+
+    for (int superblock_ix = 0; superblock_ix < superblock_count; superblock_ix += 1) {
+        int i = superblock_ix * superblock_size;
+
+        acc0 = process_one_block( acc0, pd0, pd1, pb0, pb1, i+0 );
+        acc1 = process_one_block( acc1, pd0, pd1, pb0, pb1, i+1 );
+        acc0 = process_one_block( acc0, pd0, pd1, pb0, pb1, i+2 );
+        acc1 = process_one_block( acc1, pd0, pd1, pb0, pb1, i+3 );
+        acc0 = process_one_block( acc0, pd0, pd1, pb0, pb1, i+4 );
+        acc1 = process_one_block( acc1, pd0, pd1, pb0, pb1, i+5 );
+        acc0 = process_one_block( acc0, pd0, pd1, pb0, pb1, i+6 );
+        acc1 = process_one_block( acc1, pd0, pd1, pb0, pb1, i+7 );
+    }
+
+    // Remainders
+    for (int i = superblock_count * superblock_size; i < nb; ++i) {
+        acc0 = process_one_block( acc0, pd0, pd1, pb0, pb1, i );
+    }
+
+    // Horizontal sum of all lanes of the accumulator
+    sumf = _mm512_reduce_add_ps( acc0 ) + _mm512_reduce_add_ps( acc1 );
+#else
+#error "not implemented for QK"
+#endif
 #elif defined(__AVX2__)
 #if QK == 32
     const size_t countBlocks = nb;