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go/container/intsets/popcnt_gccgo_c.c
Ian Lance Taylor d94e6fe0fd container/intsets: use fast popcount with gccgo
Use the compiler intrinsic __builtin_popcount.

Change-Id: I58286fbcf66d1068390ea9caff2f98b8fe244c2d
Reviewed-on: https://go-review.googlesource.com/16831
Reviewed-by: Andrew Gerrand <adg@golang.org>
2015-11-11 02:17:02 +00:00

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529 B
C

// 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));
}