rmuir commented on code in PR #12311: URL: https://github.com/apache/lucene/pull/12311#discussion_r1201114747
########## lucene/core/src/java20/org/apache/lucene/util/VectorUtilPanamaProvider.java: ########## @@ -0,0 +1,157 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.lucene.util; + +import jdk.incubator.vector.ByteVector; +import jdk.incubator.vector.FloatVector; +import jdk.incubator.vector.IntVector; +import jdk.incubator.vector.ShortVector; +import jdk.incubator.vector.Vector; +import jdk.incubator.vector.VectorOperators; +import jdk.incubator.vector.VectorShape; +import jdk.incubator.vector.VectorSpecies; + +/** A VectorUtil provider implementation that leverages the Panama Vector API. */ +final class VectorUtilPanamaProvider implements VectorUtilProvider { + + static final VectorSpecies<Float> SPECIES = FloatVector.SPECIES_PREFERRED; + + VectorUtilPanamaProvider() {} + + @Override + public float dotProduct(float[] a, float[] b) { + int i = 0; + float res = 0; + // if the array size is large (> 2x platform vector size), its worth the overhead to vectorize + if (a.length > 2 * SPECIES.length()) { + // vector loop is unrolled 4x (4 accumulators in parallel) + FloatVector acc1 = FloatVector.zero(SPECIES); + FloatVector acc2 = FloatVector.zero(SPECIES); + FloatVector acc3 = FloatVector.zero(SPECIES); + FloatVector acc4 = FloatVector.zero(SPECIES); + int upperBound = SPECIES.loopBound(a.length - 3 * SPECIES.length()); + for (; i < upperBound; i += 4 * SPECIES.length()) { + FloatVector va = FloatVector.fromArray(SPECIES, a, i); + FloatVector vb = FloatVector.fromArray(SPECIES, b, i); + acc1 = acc1.add(va.mul(vb)); + FloatVector vc = FloatVector.fromArray(SPECIES, a, i + SPECIES.length()); + FloatVector vd = FloatVector.fromArray(SPECIES, b, i + SPECIES.length()); + acc2 = acc2.add(vc.mul(vd)); + FloatVector ve = FloatVector.fromArray(SPECIES, a, i + 2 * SPECIES.length()); + FloatVector vf = FloatVector.fromArray(SPECIES, b, i + 2 * SPECIES.length()); + acc3 = acc3.add(ve.mul(vf)); + FloatVector vg = FloatVector.fromArray(SPECIES, a, i + 3 * SPECIES.length()); + FloatVector vh = FloatVector.fromArray(SPECIES, b, i + 3 * SPECIES.length()); + acc4 = acc4.add(vg.mul(vh)); + } + // vector tail: less scalar computations for unaligned sizes, esp with big vector sizes + upperBound = SPECIES.loopBound(a.length); + for (; i < upperBound; i += SPECIES.length()) { + FloatVector va = FloatVector.fromArray(SPECIES, a, i); + FloatVector vb = FloatVector.fromArray(SPECIES, b, i); + acc1 = acc1.add(va.mul(vb)); + } + // reduce + FloatVector res1 = acc1.add(acc2); + FloatVector res2 = acc3.add(acc4); + res += res1.add(res2).reduceLanes(VectorOperators.ADD); + } + + for (; i < a.length; i++) { + res += b[i] * a[i]; + } + return res; + } + + static final VectorSpecies<Byte> PREFERRED_BYTE_SPECIES; + static final VectorSpecies<Short> PREFERRED_SHORT_SPECIES; + + static { + if (IntVector.SPECIES_PREFERRED.vectorBitSize() >= 256) { + PREFERRED_BYTE_SPECIES = + ByteVector.SPECIES_MAX.withShape( + VectorShape.forBitSize(IntVector.SPECIES_PREFERRED.vectorBitSize() >> 2)); + PREFERRED_SHORT_SPECIES = + ShortVector.SPECIES_MAX.withShape( + VectorShape.forBitSize(IntVector.SPECIES_PREFERRED.vectorBitSize() >> 1)); + } else { + PREFERRED_BYTE_SPECIES = null; + PREFERRED_SHORT_SPECIES = null; + } + } + + @Override + public int dotProduct(byte[] a, byte[] b) { + int i = 0; + int res = 0; + final int vectorSize = IntVector.SPECIES_PREFERRED.vectorBitSize(); + // only vectorize if we'll at least enter the loop a single time, and we have at least 128-bit + // vectors + if (a.length >= 16 && vectorSize >= 128) { + // compute vectorized dot product consistent with VPDPBUSD instruction, acts like: + // int sum = 0; + // for (...) { + // short product = (short) (x[i] * y[i]); + // sum += product; + // } + if (vectorSize >= 256) { Review Comment: yeah. we should also rename constant. as well as many other variables in this messy code i am pushing. needs heavy cleanup. gimme some time, i want to get all 6 of the necessary methods (3 float[], 3 byte[]) in here and then clean up everything. -- This is an automated message from the Apache Git Service. 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