Quoting Thierry Reding (2018-02-23 05:18:28)
> From: Thierry Reding <tred...@nvidia.com>
>
> The disk cache implementation uses 64-bit atomic operations. For some
> architectures, such as 32-bit ARM, GCC will not be able to translate
> these operations into lock-free instructions and will instead rely on
> the external atomics library to provide these operations.
>
> Check at configuration time whether or not linking against libatomic
> is necessary and if so, create a dependency that can be used while
> linking the mesautil library.
>
> This is the meson equivalent of 2ef7f23820a6 ("configure: check if
> -latomic is needed for __atomic_*").
>
> Signed-off-by: Thierry Reding <tred...@nvidia.com>
> ---
> meson.build | 15 +++++++++++++++
> src/util/meson.build | 2 +-
> 2 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/meson.build b/meson.build
> index 121341a950c4..7c6f40573421 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -800,6 +800,21 @@ endif
> if cc.compiles('int main() { int n; return __atomic_load_n(&n,
> __ATOMIC_ACQUIRE); }',
> name : 'GCC atomic builtins')
> pre_args += '-DUSE_GCC_ATOMIC_BUILTINS'
> +
> + # Not all atomic calls can be turned into lock-free instructions, in which
> + # GCC will make calls into the libatomic library. Check whether we need to
> + # link with -latomic.
> + #
> + # This can happen for 64-bit atomic operations on 32-bit architectures such
> + # as ARM.
> + if not cc.links('''#include <stdint.h>
> + int main() {
> + uint64_t n;
> + return (int)__atomic_load_n(&n, __ATOMIC_ACQUIRE);
> + }''',
> + name : 'GCC atomic builtins required -latomic')
> + dep_atomic = cc.find_library('atomic')dep_atomic is undefined if the cc.links() succeeds right? Dylan
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