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b7f0150d16
This function accounts for 2% of "godoc -analysis=pointer" and this change makes it twice as fast---and simpler. Added test and benchmark. Change-Id: I8578fa42dce34df057d81f6c522a7b4e0506d09d Reviewed-on: https://go-review.googlesource.com/15211 Run-TryBot: Robert Griesemer <gri@golang.org> Reviewed-by: Ilya Tocar <ilya.tocar@intel.com> Reviewed-by: Robert Griesemer <gri@golang.org>
21 lines
465 B
Go
21 lines
465 B
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build amd64
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package intsets
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func popcnt(x word) int
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func havePOPCNT() bool
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var hasPOPCNT = havePOPCNT()
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// popcount returns the population count (number of set bits) of x.
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func popcount(x word) int {
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if hasPOPCNT {
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return popcnt(x)
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}
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return popcountTable(x) // faster than Hacker's Delight
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}
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