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
|
commit f8fa1d08d7cbfef508bab355bda80f495e928f98
Author: Ben Gamari <bgamari.foss@gmail.com>
Date: Mon Apr 17 21:04:47 2023 +0000
ghc-prim: Use C11 atomics
Previously `ghc-prim`'s atomic wrappers used the legacy `__sync_*`
family of C builtins. Here we refactor these to rather use the
appropriate C11 atomic equivalents, allowing us to be more explicit
about the expected ordering semantics.
Index: b/libraries/ghc-prim/cbits/atomic.c
===================================================================
--- a/libraries/ghc-prim/cbits/atomic.c
+++ b/libraries/ghc-prim/cbits/atomic.c
@@ -291,28 +291,36 @@ extern StgWord hs_cmpxchg8(StgWord x, St
StgWord
hs_cmpxchg8(StgWord x, StgWord old, StgWord new)
{
- return __sync_val_compare_and_swap((volatile StgWord8 *) x, (StgWord8) old, (StgWord8) new);
+ StgWord8 expected = (StgWord8) old;
+ __atomic_compare_exchange_n((StgWord8 *) x, &expected, (StgWord8) new, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+ return expected;
}
extern StgWord hs_cmpxchg16(StgWord x, StgWord old, StgWord new);
StgWord
hs_cmpxchg16(StgWord x, StgWord old, StgWord new)
{
- return __sync_val_compare_and_swap((volatile StgWord16 *) x, (StgWord16) old, (StgWord16) new);
+ StgWord16 expected = (StgWord16) old;
+ __atomic_compare_exchange_n((StgWord16 *) x, &expected, (StgWord16) new, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+ return expected;
}
extern StgWord hs_cmpxchg32(StgWord x, StgWord old, StgWord new);
StgWord
hs_cmpxchg32(StgWord x, StgWord old, StgWord new)
{
- return __sync_val_compare_and_swap((volatile StgWord32 *) x, (StgWord32) old, (StgWord32) new);
+ StgWord32 expected = (StgWord32) old;
+ __atomic_compare_exchange_n((StgWord32 *) x, &expected, (StgWord32) new, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+ return expected;
}
extern StgWord64 hs_cmpxchg64(StgWord x, StgWord64 old, StgWord64 new);
StgWord64
hs_cmpxchg64(StgWord x, StgWord64 old, StgWord64 new)
{
- return __sync_val_compare_and_swap((volatile StgWord64 *) x, old, new);
+ StgWord64 expected = (StgWord64) old;
+ __atomic_compare_exchange_n((StgWord64 *) x, &expected, (StgWord64) new, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+ return expected;
}
// Atomic exchange operations
|
