Break decodedCosineSimilarity out by HAS_AVX512

Author: michaeljmarshall

jvector-twenty/src/main/java/io/github/jbellis/jvector/vector/SimdOps.java

@@ -660,6 +660,12 @@ public static void quantizePartials(float delta, ArrayVectorFloat partials, Arra
     }
 
     public static float decodedCosineSimilarity(ArrayByteSequence encoded, int clusterCount, ArrayVectorFloat partialSums, ArrayVectorFloat aMagnitude, float bMagnitude) {
+        return HAS_AVX512
+                ? decodedCosineSimilarity512(encoded, clusterCount, partialSums, aMagnitude, bMagnitude)
+                : decodedCosineSimilarity256(encoded, clusterCount, partialSums, aMagnitude, bMagnitude);
+    }
+
+    public static float decodedCosineSimilarity512(ArrayByteSequence encoded, int clusterCount, ArrayVectorFloat partialSums, ArrayVectorFloat aMagnitude, float bMagnitude) {
         var sum = FloatVector.zero(FloatVector.SPECIES_512);
         var vaMagnitude = FloatVector.zero(FloatVector.SPECIES_512);
         var baseOffsets = encoded.get();
@@ -697,4 +703,43 @@ public static float decodedCosineSimilarity(ArrayByteSequence encoded, int clust
 
         return (float) (sumResult / Math.sqrt(aMagnitudeResult * bMagnitude));
     }
+
+    public static float decodedCosineSimilarity256(ArrayByteSequence encoded, int clusterCount, ArrayVectorFloat partialSums, ArrayVectorFloat aMagnitude, float bMagnitude) {
+        var sum = FloatVector.zero(FloatVector.SPECIES_256);
+        var vaMagnitude = FloatVector.zero(FloatVector.SPECIES_256);
+        var baseOffsets = encoded.get();
+        var partialSumsArray = partialSums.get();
+        var aMagnitudeArray = aMagnitude.get();
+
+        int[] convOffsets = scratchInt256.get();
+        int i = 0;
+        int limit = ByteVector.SPECIES_64.loopBound(baseOffsets.length);
+
+        var scale = IntVector.zero(IntVector.SPECIES_256).addIndex(clusterCount);
+
+        for (; i < limit; i += ByteVector.SPECIES_64.length()) {
+
+            ByteVector.fromArray(ByteVector.SPECIES_64, baseOffsets, i)
+                    .convertShape(VectorOperators.B2I, IntVector.SPECIES_256, 0)
+                    .lanewise(VectorOperators.AND, BYTE_TO_INT_MASK_256)
+                    .reinterpretAsInts()
+                    .add(scale)
+                    .intoArray(convOffsets,0);
+
+            var offset = i * clusterCount;
+            sum = sum.add(FloatVector.fromArray(FloatVector.SPECIES_256, partialSumsArray, offset, convOffsets, 0));
+            vaMagnitude = vaMagnitude.add(FloatVector.fromArray(FloatVector.SPECIES_256, aMagnitudeArray, offset, convOffsets, 0));
+        }
+
+        float sumResult = sum.reduceLanes(VectorOperators.ADD);
+        float aMagnitudeResult = vaMagnitude.reduceLanes(VectorOperators.ADD);
+
+        for (; i < baseOffsets.length; i++) {
+            int offset = clusterCount * i + Byte.toUnsignedInt(baseOffsets[i]);
+            sumResult += partialSumsArray[offset];
+            aMagnitudeResult += aMagnitudeArray[offset];
+        }
+
+        return (float) (sumResult / Math.sqrt(aMagnitudeResult * bMagnitude));
+    }
 }