Re: [RFC] eal: use same atomic intrinsics for gcc and clang

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

On Fri, Feb 10, 2023 at 07:56:22PM -0600, Honnappa Nagarahalli wrote:
> The size generic atomic intrinsics generate the same
> code as the size specific intrinsics for gcc. Use size
> generic intrinsics for both gcc and clang.
> 
> Fixes: 7bdccb93078e ("eal: fix ARM build with clang")
> Cc: stable@dpdk.org
> Cc: pbhagavatula@marvell.com
> 
> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>

so first of all thanks for fixing this up. it was confusing me why it
was being conditionally compiled (there was no documented rationale).

i do have a slight concern that perhaps the reason this was done was
because __atomic_exchange_n on some gcc versions or for some specific
target processor was generating less than desirable code but if nobody
else has this concern i won't get in the way since it simplifies things.

thanks!

> ---
>  lib/eal/include/generic/rte_atomic.h | 12 ------------
>  1 file changed, 12 deletions(-)
> 
> diff --git a/lib/eal/include/generic/rte_atomic.h b/lib/eal/include/generic/rte_atomic.h
> index f5c49a9870..234b268b91 100644
> --- a/lib/eal/include/generic/rte_atomic.h
> +++ b/lib/eal/include/generic/rte_atomic.h
> @@ -176,11 +176,7 @@ rte_atomic16_exchange(volatile uint16_t *dst, uint16_t val);
>  static inline uint16_t
>  rte_atomic16_exchange(volatile uint16_t *dst, uint16_t val)
>  {
> -#if defined(__clang__)
>  	return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
> -#else
> -	return __atomic_exchange_2(dst, val, __ATOMIC_SEQ_CST);
> -#endif
>  }
>  #endif
>  
> @@ -459,11 +455,7 @@ rte_atomic32_exchange(volatile uint32_t *dst, uint32_t val);
>  static inline uint32_t
>  rte_atomic32_exchange(volatile uint32_t *dst, uint32_t val)
>  {
> -#if defined(__clang__)
>  	return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
> -#else
> -	return __atomic_exchange_4(dst, val, __ATOMIC_SEQ_CST);
> -#endif
>  }
>  #endif
>  
> @@ -741,11 +733,7 @@ rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val);
>  static inline uint64_t
>  rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val)
>  {
> -#if defined(__clang__)
>  	return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
> -#else
> -	return __atomic_exchange_8(dst, val, __ATOMIC_SEQ_CST);
> -#endif
>  }
>  #endif
>  
> -- 
> 2.25.1