Mon, 23 Jun 2008 14:11:12 -0700
6708714: Optimize long LShift on 32-bits x86
Summary: For small (1-3 bits) left long shifts in 32-bits VM use sets of add+addc instructions instead of shld+shl on new AMD cpus.
Reviewed-by: never
Contributed-by: shrinivas.joshi@amd.com
1 /*
2 * Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_atomic.cpp.incl"
28 jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
29 assert(sizeof(jbyte) == 1, "assumption.");
30 uintptr_t dest_addr = (uintptr_t)dest;
31 uintptr_t offset = dest_addr % sizeof(jint);
32 volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
33 jint cur = *dest_int;
34 jbyte* cur_as_bytes = (jbyte*)(&cur);
35 jint new_val = cur;
36 jbyte* new_val_as_bytes = (jbyte*)(&new_val);
37 new_val_as_bytes[offset] = exchange_value;
38 while (cur_as_bytes[offset] == compare_value) {
39 jint res = cmpxchg(new_val, dest_int, cur);
40 if (res == cur) break;
41 cur = res;
42 new_val = cur;
43 new_val_as_bytes[offset] = exchange_value;
44 }
45 return cur_as_bytes[offset];
46 }
48 unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) {
49 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
50 return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest);
51 }
53 unsigned Atomic::cmpxchg(unsigned int exchange_value,
54 volatile unsigned int* dest, unsigned int compare_value) {
55 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
56 return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest,
57 (jint)compare_value);
58 }