blob: 230ed87c43f74560ceab20f5ab267975c97b395d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Lock-free stack.
#include "runtime.h"
#include "arch.h"
#if __SIZEOF_POINTER__ == 8
// Amd64 uses 48-bit virtual addresses, 47-th bit is used as kernel/user flag.
// So we use 17msb of pointers as ABA counter.
# define PTR_BITS 47
#else
# define PTR_BITS 32
#endif
#define PTR_MASK ((1ull<<PTR_BITS)-1)
#define CNT_MASK (0ull-1)
#if __SIZEOF_POINTER__ == 8 && (defined(__sparc__) || (defined(__sun__) && defined(__amd64__)))
// SPARC64 and Solaris on AMD64 uses all 64 bits of virtual addresses.
// Use low-order three bits as ABA counter.
// http://docs.oracle.com/cd/E19120-01/open.solaris/816-5138/6mba6ua5p/index.html
#undef PTR_BITS
#undef CNT_MASK
#undef PTR_MASK
#define PTR_BITS 0
#define CNT_MASK 7
#define PTR_MASK ((0ull-1)<<3)
#endif
void
runtime_lfstackpush(uint64 *head, LFNode *node)
{
uint64 old, new;
if((uintptr)node != ((uintptr)node&PTR_MASK)) {
runtime_printf("p=%p\n", node);
runtime_throw("runtime_lfstackpush: invalid pointer");
}
node->pushcnt++;
new = (uint64)(uintptr)node|(((uint64)node->pushcnt&CNT_MASK)<<PTR_BITS);
old = runtime_atomicload64(head);
for(;;) {
node->next = (LFNode*)(uintptr)(old&PTR_MASK);
if(runtime_cas64(head, &old, new))
break;
}
}
LFNode*
runtime_lfstackpop(uint64 *head)
{
LFNode *node, *node2;
uint64 old, new;
old = runtime_atomicload64(head);
for(;;) {
if(old == 0)
return nil;
node = (LFNode*)(uintptr)(old&PTR_MASK);
node2 = runtime_atomicloadp(&node->next);
new = 0;
if(node2 != nil)
new = (uint64)(uintptr)node2|(((uint64)node2->pushcnt&CNT_MASK)<<PTR_BITS);
if(runtime_cas64(head, &old, new))
return node;
}
}
LFNode* runtime_lfstackpop2(uint64*)
__asm__ (GOSYM_PREFIX "runtime.lfstackpop2");
LFNode*
runtime_lfstackpop2(uint64 *head)
{
return runtime_lfstackpop(head);
}
|
