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| author | Torvald Riegel <torvald@gcc.gnu.org> | 2017-02-01 17:21:59 +0000 |
|---|---|---|
| committer | Torvald Riegel <torvald@gcc.gnu.org> | 2017-02-01 17:21:59 +0000 |
| commit | 969a32ce9354585f5f2b89df2e025f52eb0e1644 (patch) | |
| tree | ba5dc4787f7d4f9d23224810508207f4fcc188dc /libatomic/config | |
| parent | 55e75c7c6bcfe386d0ecbf4611cff81040af00b3 (diff) | |
| download | gcc-969a32ce9354585f5f2b89df2e025f52eb0e1644.zip gcc-969a32ce9354585f5f2b89df2e025f52eb0e1644.tar.gz gcc-969a32ce9354585f5f2b89df2e025f52eb0e1644.tar.bz2 | |
Fix __atomic to not implement atomic loads with CAS.
gcc/
* builtins.c (fold_builtin_atomic_always_lock_free): Make "lock-free"
conditional on existance of a fast atomic load.
* optabs-query.c (can_atomic_load_p): New function.
* optabs-query.h (can_atomic_load_p): Declare it.
* optabs.c (expand_atomic_exchange): Always delegate to libatomic if
no fast atomic load is available for the particular size of access.
(expand_atomic_compare_and_swap): Likewise.
(expand_atomic_load): Likewise.
(expand_atomic_store): Likewise.
(expand_atomic_fetch_op): Likewise.
* testsuite/lib/target-supports.exp
(check_effective_target_sync_int_128): Remove x86 because it provides
no fast atomic load.
(check_effective_target_sync_int_128_runtime): Likewise.
libatomic/
* acinclude.m4: Add #define FAST_ATOMIC_LDST_*.
* auto-config.h.in: Regenerate.
* config/x86/host-config.h (FAST_ATOMIC_LDST_16): Define to 0.
(atomic_compare_exchange_n): New.
* glfree.c (EXACT, LARGER): Change condition and add comments.
From-SVN: r245098
Diffstat (limited to 'libatomic/config')
| -rw-r--r-- | libatomic/config/x86/host-config.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/libatomic/config/x86/host-config.h b/libatomic/config/x86/host-config.h index 5754db4..2e9f85a 100644 --- a/libatomic/config/x86/host-config.h +++ b/libatomic/config/x86/host-config.h @@ -47,6 +47,9 @@ extern unsigned int libat_feat1_edx HIDDEN; # define MAYBE_HAVE_ATOMIC_EXCHANGE_16 IFUNC_COND_1 # undef MAYBE_HAVE_ATOMIC_LDST_16 # define MAYBE_HAVE_ATOMIC_LDST_16 IFUNC_COND_1 +/* Since load and store are implemented with CAS, they are not fast. */ +# undef FAST_ATOMIC_LDST_16 +# define FAST_ATOMIC_LDST_16 0 # if IFUNC_ALT == 1 # undef HAVE_ATOMIC_CAS_16 # define HAVE_ATOMIC_CAS_16 1 @@ -64,6 +67,21 @@ extern unsigned int libat_feat1_edx HIDDEN; # endif #endif +#if defined(__x86_64__) && N == 16 && IFUNC_ALT == 1 +static inline bool +atomic_compare_exchange_n (UTYPE *mptr, UTYPE *eptr, UTYPE newval, + bool weak_p UNUSED, int sm UNUSED, int fm UNUSED) +{ + UTYPE cmpval = *eptr; + UTYPE oldval = __sync_val_compare_and_swap_16 (mptr, cmpval, newval); + if (oldval == cmpval) + return true; + *eptr = oldval; + return false; +} +# define atomic_compare_exchange_n atomic_compare_exchange_n +#endif /* Have CAS 16 */ + #endif /* HAVE_IFUNC */ #include_next <host-config.h> |