• file
• revisions
• annotate
• diff
• comparison
• raw

src/share/vm/runtime/atomic.cpp@595c0f60d50d (annotated)

src/share/vm/runtime/atomic.cpp

Tue, 18 Mar 2014 19:07:22 +0100

author

pliden

date

Tue, 18 Mar 2014 19:07:22 +0100

changeset 6413

595c0f60d50d

parent 6198

55fb97c4c58d

child 6503

a9becfeecd1b

permissions

-rw-r--r--

8029075: String deduplication in G1
Summary: Implementation of JEP 192, http://openjdk.java.net/jeps/192
Reviewed-by: brutisso, tschatzl, coleenp

duke@435	1	/*
mikael@6198	2	* Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
stefank@2314	25	#include "precompiled.hpp"
stefank@2314	26	#include "runtime/atomic.hpp"
stefank@2314	27	#ifdef TARGET_OS_FAMILY_linux
stefank@2314	28	# include "os_linux.inline.hpp"
stefank@2314	29	#endif
stefank@2314	30	#ifdef TARGET_OS_FAMILY_solaris
stefank@2314	31	# include "os_solaris.inline.hpp"
stefank@2314	32	#endif
stefank@2314	33	#ifdef TARGET_OS_FAMILY_windows
stefank@2314	34	# include "os_windows.inline.hpp"
stefank@2314	35	#endif
never@3156	36	#ifdef TARGET_OS_FAMILY_bsd
never@3156	37	# include "os_bsd.inline.hpp"
never@3156	38	#endif
twisti@4318	39
twisti@4318	40	#include "runtime/atomic.inline.hpp"
duke@435	41
duke@435	42	jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
duke@435	43	assert(sizeof(jbyte) == 1, "assumption.");
duke@435	44	uintptr_t dest_addr = (uintptr_t)dest;
duke@435	45	uintptr_t offset = dest_addr % sizeof(jint);
duke@435	46	volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
duke@435	47	jint cur = *dest_int;
duke@435	48	jbyte* cur_as_bytes = (jbyte*)(&cur);
duke@435	49	jint new_val = cur;
duke@435	50	jbyte* new_val_as_bytes = (jbyte*)(&new_val);
duke@435	51	new_val_as_bytes[offset] = exchange_value;
duke@435	52	while (cur_as_bytes[offset] == compare_value) {
duke@435	53	jint res = cmpxchg(new_val, dest_int, cur);
duke@435	54	if (res == cur) break;
duke@435	55	cur = res;
duke@435	56	new_val = cur;
duke@435	57	new_val_as_bytes[offset] = exchange_value;
duke@435	58	}
duke@435	59	return cur_as_bytes[offset];
duke@435	60	}
coleenp@548	61
coleenp@548	62	unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) {
coleenp@548	63	assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
coleenp@548	64	return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest);
coleenp@548	65	}
coleenp@548	66
coleenp@548	67	unsigned Atomic::cmpxchg(unsigned int exchange_value,
coleenp@548	68	volatile unsigned int* dest, unsigned int compare_value) {
coleenp@548	69	assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
coleenp@548	70	return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest,
coleenp@548	71	(jint)compare_value);
coleenp@548	72	}
minqi@2964	73
minqi@2964	74	jlong Atomic::add(jlong add_value, volatile jlong* dest) {
minqi@2964	75	jlong old = load(dest);
minqi@2964	76	jlong new_value = old + add_value;
minqi@2964	77	while (old != cmpxchg(new_value, dest, old)) {
minqi@2964	78	old = load(dest);
minqi@2964	79	new_value = old + add_value;
minqi@2964	80	}
minqi@2964	81	return old;
minqi@2964	82	}
iklam@5306	83
iklam@5306	84	void Atomic::inc(volatile short* dest) {
iklam@5306	85	// Most platforms do not support atomic increment on a 2-byte value. However,
iklam@5306	86	// if the value occupies the most significant 16 bits of an aligned 32-bit
iklam@5306	87	// word, then we can do this with an atomic add of 0x10000 to the 32-bit word.
iklam@5306	88	//
iklam@5306	89	// The least significant parts of this 32-bit word will never be affected, even
iklam@5306	90	// in case of overflow/underflow.
iklam@5306	91	//
iklam@5306	92	// Use the ATOMIC_SHORT_PAIR macro to get the desired alignment.
iklam@5306	93	#ifdef VM_LITTLE_ENDIAN
iklam@5306	94	assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
iklam@5306	95	(void)Atomic::add(0x10000, (volatile int*)(dest-1));
iklam@5306	96	#else
iklam@5306	97	assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
iklam@5306	98	(void)Atomic::add(0x10000, (volatile int*)(dest));
iklam@5306	99	#endif
iklam@5306	100	}
iklam@5306	101
iklam@5306	102	void Atomic::dec(volatile short* dest) {
iklam@5306	103	#ifdef VM_LITTLE_ENDIAN
iklam@5306	104	assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
iklam@5306	105	(void)Atomic::add(-0x10000, (volatile int*)(dest-1));
iklam@5306	106	#else
iklam@5306	107	assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
iklam@5306	108	(void)Atomic::add(-0x10000, (volatile int*)(dest));
iklam@5306	109	#endif
iklam@5306	110	}
iklam@5306	111