Initial commit

vendor/golang.org/x/tools/container/intsets/popcnt_amd64.go

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+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64,!appengine,!gccgo
+
+package intsets
+
+func popcnt(x word) int
+func havePOPCNT() bool
+
+var hasPOPCNT = havePOPCNT()
+
+// popcount returns the population count (number of set bits) of x.
+func popcount(x word) int {
+	if hasPOPCNT {
+		return popcnt(x)
+	}
+	return popcountTable(x) // faster than Hacker's Delight
+}

vendor/golang.org/x/tools/container/intsets/popcnt_amd64.s

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+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64,!appengine,!gccgo
+
+#include "textflag.h"
+
+// func havePOPCNT() bool
+TEXT ·havePOPCNT(SB),4,$0
+	MOVQ	$1, AX
+	CPUID
+	SHRQ	$23, CX
+	ANDQ	$1, CX
+	MOVB	CX, ret+0(FP)
+	RET
+
+// func popcnt(word) int
+TEXT ·popcnt(SB),NOSPLIT,$0-8
+	XORQ	AX, AX
+	MOVQ	x+0(FP), SI
+	// POPCNT (SI), AX is not recognized by Go assembler,
+	// so we assemble it ourselves.
+	BYTE	$0xf3
+	BYTE	$0x48
+	BYTE	$0x0f
+	BYTE	$0xb8
+	BYTE	$0xc6
+	MOVQ	AX, ret+8(FP)
+	RET

vendor/golang.org/x/tools/container/intsets/popcnt_gccgo.go

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+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build gccgo
+
+package intsets
+
+func popcount(x word) int

vendor/golang.org/x/tools/container/intsets/popcnt_gccgo_c.c

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+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build gccgo
+
+#include <errno.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#define _STRINGIFY2_(x) #x
+#define _STRINGIFY_(x) _STRINGIFY2_(x)
+#define GOSYM_PREFIX _STRINGIFY_(__USER_LABEL_PREFIX__)
+
+extern intptr_t popcount(uintptr_t x) __asm__(GOSYM_PREFIX GOPKGPATH ".popcount");
+
+intptr_t popcount(uintptr_t x) {
+	return __builtin_popcountl((unsigned long)(x));
+}

vendor/golang.org/x/tools/container/intsets/popcnt_generic.go

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+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !amd64 appengine
+// +build !gccgo
+
+package intsets
+
+import "runtime"
+
+// We compared three algorithms---Hacker's Delight, table lookup,
+// and AMD64's SSE4.1 hardware POPCNT---on a 2.67GHz Xeon X5550.
+//
+// % GOARCH=amd64 go test -run=NONE -bench=Popcount
+// POPCNT               5.12 ns/op
+// Table                8.53 ns/op
+// HackersDelight       9.96 ns/op
+//
+// % GOARCH=386 go test -run=NONE -bench=Popcount
+// Table               10.4  ns/op
+// HackersDelight       5.23 ns/op
+//
+// (AMD64's ABM1 hardware supports ntz and nlz too,
+// but they aren't critical.)
+
+// popcount returns the population count (number of set bits) of x.
+func popcount(x word) int {
+	if runtime.GOARCH == "386" {
+		return popcountHD(uint32(x))
+	}
+	return popcountTable(x)
+}

vendor/golang.org/x/tools/container/intsets/util.go

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+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package intsets
+
+// From Hacker's Delight, fig 5.2.
+func popcountHD(x uint32) int {
+	x -= (x >> 1) & 0x55555555
+	x = (x & 0x33333333) + ((x >> 2) & 0x33333333)
+	x = (x + (x >> 4)) & 0x0f0f0f0f
+	x = x + (x >> 8)
+	x = x + (x >> 16)
+	return int(x & 0x0000003f)
+}
+
+var a [1 << 8]byte
+
+func init() {
+	for i := range a {
+		var n byte
+		for x := i; x != 0; x >>= 1 {
+			if x&1 != 0 {
+				n++
+			}
+		}
+		a[i] = n
+	}
+}
+
+func popcountTable(x word) int {
+	return int(a[byte(x>>(0*8))] +
+		a[byte(x>>(1*8))] +
+		a[byte(x>>(2*8))] +
+		a[byte(x>>(3*8))] +
+		a[byte(x>>(4*8))] +
+		a[byte(x>>(5*8))] +
+		a[byte(x>>(6*8))] +
+		a[byte(x>>(7*8))])
+}
+
+// nlz returns the number of leading zeros of x.
+// From Hacker's Delight, fig 5.11.
+func nlz(x word) int {
+	x |= (x >> 1)
+	x |= (x >> 2)
+	x |= (x >> 4)
+	x |= (x >> 8)
+	x |= (x >> 16)
+	x |= (x >> 32)
+	return popcount(^x)
+}
+
+// ntz returns the number of trailing zeros of x.
+// From Hacker's Delight, fig 5.13.
+func ntz(x word) int {
+	if x == 0 {
+		return bitsPerWord
+	}
+	n := 1
+	if bitsPerWord == 64 {
+		if (x & 0xffffffff) == 0 {
+			n = n + 32
+			x = x >> 32
+		}
+	}
+	if (x & 0x0000ffff) == 0 {
+		n = n + 16
+		x = x >> 16
+	}
+	if (x & 0x000000ff) == 0 {
+		n = n + 8
+		x = x >> 8
+	}
+	if (x & 0x0000000f) == 0 {
+		n = n + 4
+		x = x >> 4
+	}
+	if (x & 0x00000003) == 0 {
+		n = n + 2
+		x = x >> 2
+	}
+	return n - int(x&1)
+}