From aaf3291466b7d04b830fca2cc53f93ba0b661d8b Mon Sep 17 00:00:00 2001
From: Nikolay Bogoychev <nheart@gmail.com>
Date: Thu, 11 Apr 2019 18:43:16 +0100
Subject: WiP

---
 ssse3_gemm.h | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 77 insertions(+), 6 deletions(-)

(limited to 'ssse3_gemm.h')

diff --git a/ssse3_gemm.h b/ssse3_gemm.h
index 4993ef6..69ac298 100644
--- a/ssse3_gemm.h
+++ b/ssse3_gemm.h
@@ -3,32 +3,103 @@
 #include <cstdint>
 #include <stdint.h>
 
+#include "interleave.h"
+#include "multiply.h"
+
 // 16-bit is in sse2_gemm.h
 
 namespace intgemm {
 
+namespace ssse3 {
+// Same implementation as AVX512, just width.  Grabs 4 32-bit values.
+//TODO duplicated function requires the removal of the annonymous namespace
+SSSE3 inline __m128i QuantizerGrab(const float *input, const __m128 quant_mult_reg) {
+  return _mm_cvtps_epi32(_mm_mul_ps(*reinterpret_cast<const __m128*>(input), quant_mult_reg));
+}
+
+class QuantizeTile8 {
+  public:
+    typedef __m128i Integer;
+
+    SSSE3 explicit QuantizeTile8(float mult) : mult_reg_(_mm_set1_ps(mult)) {}
+
+    SSSE3 inline __m128i ForReshape(const float *input, Index cols) {
+      // Skip a row.
+      return Tile(input, input + 2 * cols);
+    }
+
+    SSSE3 inline __m128i Consecutive(const float *input) {
+      return Tile(input, input + 8);
+    }
+
+  private:
+    // Quantize 16xfloat into 16xint8_t
+    SSSE3 inline __m128i Tile(const float *input0, const float *input1) {
+      const __m128i neg128 = _mm_set1_epi8(-128);
+      __m128i g0 = QuantizerGrab(input0, mult_reg_);
+      __m128i g1 = QuantizerGrab(input0 + 4, mult_reg_);
+      __m128i g2 = QuantizerGrab(input1, mult_reg_);
+      __m128i g3 = QuantizerGrab(input1 + 4, mult_reg_);
+      __m128i packed0 = _mm_packs_epi32(g0, g1);
+      __m128i packed1 = _mm_packs_epi32(g2, g3);
+      __m128i packed = _mm_packs_epi16(packed0, packed1);
+      /* Ban -128.
+       * Don't use the SSE4.1 instruction _mm_max_epi8(packed, neg127).  Instead,
+       * use SSE2 instructions _mm_cmpeq_epi8 and _mm_sub_epi8.
+       * The first generates 0xff for fields -128.
+       * The second subtracts 0xff from -128 which has the effect of converting
+       * to -127.
+       */
+      // packed = _mm_max_epi8(packed, neg127);
+      __m128i evils = _mm_cmpeq_epi8(packed, neg128);
+      return _mm_sub_epi8(packed, evils);
+      // No permute needed.  packs is in order for SSE.
+    }
+
+  private:
+    const __m128 mult_reg_;
+};
+
+} // namespace
+
+
 // pmaddubsw (the 8-bit multiply) is SSSE3, so pedantically that's the version we need.
 struct SSSE3_8bit {
   typedef int8_t Integer;
 
   // Currently A is prepared by quantization but this could theoretically change.
-  static inline void PrepareA(const float *input, int8_t *output, float quant_mult, Index rows, Index cols) {
+  SSSE3 static inline void PrepareA(const float *input, int8_t *output, float quant_mult, Index rows, Index cols) {
     Quantize(input, output, quant_mult, rows * cols);
   }
 
-  static void Quantize(const float *input, int8_t *output, float quant_mult, Index size);
+  SSSE3 static void Quantize(const float *input, int8_t *output, float quant_mult, Index size) {
+    assert(size % 16 == 0);
+    assert(reinterpret_cast<uintptr_t>(input) % 16 == 0);
+    assert(reinterpret_cast<uintptr_t>(output) % 16 == 0);
+    ssse3::QuantizeTile8 q(quant_mult);
+    const float *end = input + size;
+    for (; input != end; input += 16, output += 16) {
+      *reinterpret_cast<__m128i*>(output) = q.Consecutive(input);
+    }
+  }
 
   // Tile size for B; B must be a multiple of this block size.
   static const Index kBTileRow = 16;
   static const Index kBTileCol = 8;
 
-  static void PrepareB(const float *input, int8_t *output, float quant_mult, Index rows, Index cols);
+  SSSE3 static void PrepareB(const float *input, int8_t *output, float quant_mult, Index rows, Index cols) {
+    PrepareBFor8(input, output, ssse3::QuantizeTile8(quant_mult), rows, cols);
+  }
 
-  static void SelectColumnsB(const int8_t *input, int8_t *output, Index rows, const Index *cols_begin, const Index *cols_end);
+  SSSE3 static void SelectColumnsB(const int8_t *input, int8_t *output, Index rows, const Index *cols_begin, const Index *cols_end) {
+    SelectColumnsOfB((const __m128i*)input, (__m128i*)output, rows, cols_begin, cols_end);
+  }
 
-  static void Multiply(const int8_t *A, const int8_t *B, float *C, float unquant_mult, Index A_rows, Index width, Index B_cols);
+  SSSE3 static void Multiply(const int8_t *A, const int8_t *B, float *C, float unquant_mult, Index A_rows, Index width, Index B_cols) {
+    Multiply8_SSE2OrAVX2<Multiply8_C, __m128i, __m128>(A, B, C, unquant_mult, A_rows, width, B_cols);
+  }
   
-  static const char *const kName;
+  constexpr static const char *const kName = "8-bit SSSE3";
 
   static const CPUType kUses = CPU_SSSE3;
 };
-- 
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