jdk-sandbox: src/hotspot/share/utilities/count_trailing

46437 cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	1	/*
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	2	* Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	4	*
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	5	* This code is free software; you can redistribute it and/or modify it
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	6	* under the terms of the GNU General Public License version 2 only, as
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	7	* published by the Free Software Foundation.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	8	*
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	9	* This code is distributed in the hope that it will be useful, but WITHOUT
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	12	* version 2 for more details (a copy is included in the LICENSE file that
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	13	* accompanied this code).
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	14	*
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	15	* You should have received a copy of the GNU General Public License version
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	16	* 2 along with this work; if not, write to the Free Software Foundation,
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	18	*
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	20	* or visit www.oracle.com if you need additional information or have any
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	21	* questions.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	22	*
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	23	*/
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	24
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	25	#ifndef SHARE_VM_UTILITIES_COUNTTRAILINGZEROS_HPP
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	26	#define SHARE_VM_UTILITIES_COUNTTRAILINGZEROS_HPP
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	27
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	28	#include "utilities/debug.hpp"
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	29	#include "utilities/globalDefinitions.hpp"
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	30
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	31	// unsigned count_trailing_zeros(uintx x)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	32	// Return the number of trailing zeros in x, e.g. the zero-based index
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	33	// of the least significant set bit in x.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	34	// Precondition: x != 0.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	35
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	36	// Dispatch on toolchain to select implementation.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	37
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	38	/*****************************************************************************
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	39	* GCC and compatible (including Clang)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	40	*****************************************************************************/
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	41	#if defined(TARGET_COMPILER_gcc)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	42
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	43	inline unsigned count_trailing_zeros(uintx x) {
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	44	STATIC_ASSERT(sizeof(unsigned long) == sizeof(uintx));
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	45	assert(x != 0, "precondition");
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	46	return __builtin_ctzl(x);
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	47	}
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	48
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	49	/*****************************************************************************
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	50	* Microsoft Visual Studio
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	51	*****************************************************************************/
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	52	#elif defined(TARGET_COMPILER_visCPP)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	53
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	54	#include <intrin.h>
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	55
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	56	#ifdef _LP64
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	57	#pragma intrinsic(_BitScanForward64)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	58	#else
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	59	#pragma intrinsic(_BitScanForward)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	60	#endif
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	61
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	62	inline unsigned count_trailing_zeros(uintx x) {
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	63	assert(x != 0, "precondition");
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	64	unsigned long index;
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	65	#ifdef _LP64
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	66	_BitScanForward64(&index, x);
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	67	#else
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	68	_BitScanForward(&index, x);
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	69	#endif
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	70	return index;
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	71	}
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	72
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	73	/*****************************************************************************
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	74	* IBM XL C/C++
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	75	*****************************************************************************/
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	76	#elif defined(TARGET_COMPILER_xlc)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	77
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	78	#include <builtins.h>
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	79
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	80	inline unsigned count_trailing_zeros(uintx x) {
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	81	assert(x != 0, "precondition");
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	82	#ifdef _LP64
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	83	return __cnttz8(x);
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	84	#else
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	85	return __cnttz4(x);
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	86	#endif
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	87	}
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	88
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	89	/*****************************************************************************
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	90	* Oracle Studio
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	91	*****************************************************************************/
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	92	#elif defined(TARGET_COMPILER_sparcWorks)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	93
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	94	// No compiler built-in / intrinsic, so use inline assembler.
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	95
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	96	#include "utilities/macros.hpp"
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	97
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	98	#include OS_CPU_HEADER(count_trailing_zeros)
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	99
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	100	/*****************************************************************************
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	101	* Unknown toolchain
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	102	*****************************************************************************/
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	103	#else
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	104	#error Unknown TARGET_COMPILER
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	105
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	106	#endif // Toolchain dispatch
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	107
cda23e690843 8179004: Add an efficient implementation of the "count trailing zeros" operation kbarrett parents: diff changeset	108	#endif // include guard

author	stefank
	Tue, 28 Nov 2017 21:43:45 +0100
changeset 48157	7c4d43c26352
parent 47216	71c04702a3d5
child 51605	2ca553d34949
permissions	-rw-r--r--