From ecb64a53a940bf93c870c3eb271055bcda9fd4f3 Mon Sep 17 00:00:00 2001
From: Alden Torres <aldenml@gmail.com>
Date: Tue, 28 Jun 2016 00:34:21 -0400
Subject: [PATCH] backport of popcnt asm for x86 and gcc/clang (#864)

backport of popcnt asm for x86 and gcc/clang
---
 src/bitfield.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/bitfield.cpp b/src/bitfield.cpp
index 089491b1c..dab1d2259 100644
--- a/src/bitfield.cpp
+++ b/src/bitfield.cpp
@@ -65,7 +65,11 @@ namespace libtorrent
 			for (int i = 0; i < words; ++i)
 			{
 #ifdef __GNUC__
-				ret += __builtin_popcount(m_buf[i]);
+				boost::uint32_t cnt = 0;
+				__asm__("popcnt %1, %0"
+					: "=r"(cnt)
+					: "r"(m_buf[i]));
+				ret += cnt;
 #else
 				ret += _mm_popcnt_u32(m_buf[i]);
 #endif