From 969a32ce9354585f5f2b89df2e025f52eb0e1644 Mon Sep 17 00:00:00 2001 From: Torvald Riegel Date: Wed, 1 Feb 2017 17:21:59 +0000 Subject: 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 --- libatomic/config/x86/host-config.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'libatomic/config') 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 -- cgit v1.1