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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 /gcc/builtins.c | |
| 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 'gcc/builtins.c')
| -rw-r--r-- | gcc/builtins.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/gcc/builtins.c b/gcc/builtins.c index bf68e31..0a0e8b9 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -6157,8 +6157,9 @@ fold_builtin_atomic_always_lock_free (tree arg0, tree arg1) /* Check if a compare_and_swap pattern exists for the mode which represents the required size. The pattern is not allowed to fail, so the existence - of the pattern indicates support is present. */ - if (can_compare_and_swap_p (mode, true)) + of the pattern indicates support is present. Also require that an + atomic load exists for the required size. */ + if (can_compare_and_swap_p (mode, true) && can_atomic_load_p (mode)) return boolean_true_node; else return boolean_false_node; |