zeroshade commented on a change in pull request #9671: URL: https://github.com/apache/arrow/pull/9671#discussion_r595189145
########## File path: go/parquet/internal/bmi/bmi_init.go ########## @@ -0,0 +1,66 @@ +// 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 bmi + +import ( + "golang.org/x/sys/cpu" +) + +type funcs struct { + extractBits func(uint64, uint64) uint64 + popcount64 func(uint64) uint64 + popcount32 func(uint32) uint32 + gtbitmap func([]int16, int16) uint64 +} + +var funclist funcs + +func init() { + if cpu.X86.HasPOPCNT { + funclist.popcount64 = popCount64BMI2 Review comment: just to alleviate curiosity, i tried comparing the calls without the indirection and `bits.OnesCount` is still faster even though the calls for the popcnt drop down to ~1.8 ns/op so that confirms that despite my initial assumption, the builtin OnesCount is indeed more efficient in addition to being portable. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
