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| author | Ian Lance Taylor <ian@gcc.gnu.org> | 2019-02-06 20:46:00 +0000 |
|---|---|---|
| committer | Ian Lance Taylor <ian@gcc.gnu.org> | 2019-02-06 20:46:00 +0000 |
| commit | 73fe55d7522864d20026dc8d427026dc4078f9cc (patch) | |
| tree | e70328d426f425d14f9064eb8c7cc43c12f1772f | |
| parent | 16e2bcd5b9371ca6062bf035bc1d6b88540841d1 (diff) | |
| download | gcc-73fe55d7522864d20026dc8d427026dc4078f9cc.zip gcc-73fe55d7522864d20026dc8d427026dc4078f9cc.tar.gz gcc-73fe55d7522864d20026dc8d427026dc4078f9cc.tar.bz2 | |
re PR go/89199 (libgo regression in implementation of CompareAndSwap functions resulting in intermittent testcase failures on ppc64le power9 after r268458)
PR go/89199
sync/atomic: use strong form of atomic_compare_exchange_n
In the recent change to use atomic_compare_exchange_n I thought we
could use the weak form, which can spuriously fail. But that is not
how it is implemented in the gc library, and it is not what the rest
of the library expects.
Thanks to Lynn Boger for identifying the problem.
Fixes https://gcc.gnu.org/PR89199
Reviewed-on: https://go-review.googlesource.com/c/161359
From-SVN: r268591
| -rw-r--r-- | gcc/go/gofrontend/MERGE | 2 | ||||
| -rw-r--r-- | libgo/go/sync/atomic/atomic.c | 10 |
2 files changed, 6 insertions, 6 deletions
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE index 100d30e2..63499b3 100644 --- a/gcc/go/gofrontend/MERGE +++ b/gcc/go/gofrontend/MERGE @@ -1,4 +1,4 @@ -74ffeddbe6fef446129af65581b3a9094715bc22 +d89db31db68d09aa13a6137122cc096c1d92597b The first line of this file holds the git revision number of the last merge done from the gofrontend repository. diff --git a/libgo/go/sync/atomic/atomic.c b/libgo/go/sync/atomic/atomic.c index 25e439d..90a4ff3 100644 --- a/libgo/go/sync/atomic/atomic.c +++ b/libgo/go/sync/atomic/atomic.c @@ -69,7 +69,7 @@ _Bool CompareAndSwapInt32 (int32_t *, int32_t, int32_t) _Bool CompareAndSwapInt32 (int32_t *val, int32_t old, int32_t new) { - return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST, + return __atomic_compare_exchange_n (val, &old, new, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED); } @@ -82,7 +82,7 @@ CompareAndSwapInt64 (int64_t *val, int64_t old, int64_t new) { if (((uintptr_t) val & 7) != 0) val = NULL; - return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST, + return __atomic_compare_exchange_n (val, &old, new, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED); } @@ -93,7 +93,7 @@ _Bool CompareAndSwapUint32 (uint32_t *, uint32_t, uint32_t) _Bool CompareAndSwapUint32 (uint32_t *val, uint32_t old, uint32_t new) { - return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST, + return __atomic_compare_exchange_n (val, &old, new, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED); } @@ -106,7 +106,7 @@ CompareAndSwapUint64 (uint64_t *val, uint64_t old, uint64_t new) { if (((uintptr_t) val & 7) != 0) val = NULL; - return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST, + return __atomic_compare_exchange_n (val, &old, new, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED); } @@ -117,7 +117,7 @@ _Bool CompareAndSwapUintptr (uintptr_t *, uintptr_t, uintptr_t) _Bool CompareAndSwapUintptr (uintptr_t *val, uintptr_t old, uintptr_t new) { - return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST, + return __atomic_compare_exchange_n (val, &old, new, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED); } |