hotspot/src/os_cpu/solaris_x86/vm/count_trailing_zeros_solaris_x86.hpp
author kbarrett
Fri, 05 May 2017 16:20:42 -0400
changeset 46437 cda23e690843
permissions -rw-r--r--
8179004: Add an efficient implementation of the "count trailing zeros" operation Summary: Added count_trailing_zeros function, with platform-dependent implementations. Reviewed-by: dholmes, cjplummer

/*
 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef OS_CPU_SOLARIS_X86_VM_COUNTTRAILINGZEROS_HPP
#define OS_CPU_SOLARIS_X86_VM_COUNTTRAILINGZEROS_HPP

#include "utilities/globalDefinitions.hpp"

inline unsigned count_trailing_zeros(uintx x) {
  assert(x != 0, "precondition");
  uintx result;
  __asm__(" rep bsfq %1, %0" : "=r" (result) : "rm" (x));
  return result;
}

#endif // include guard