[PATCH 3/9] eal: use barrier intrinsics when compiling with msvc

[Bruce Richardson]

On Mon, Apr 03, 2023 at 02:52:25PM -0700, Tyler Retzlaff wrote:
> Inline assembly is not supported for msvc x64 instead use
> _{Read,Write,ReadWrite}Barrier() intrinsics.
> 
> Signed-off-by: Tyler Retzlaff <roretzla at linux.microsoft.com>
> ---
>  lib/eal/include/generic/rte_atomic.h |  4 ++++
>  lib/eal/x86/include/rte_atomic.h     | 10 +++++++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/eal/include/generic/rte_atomic.h b/lib/eal/include/generic/rte_atomic.h
> index 234b268..e973184 100644
> --- a/lib/eal/include/generic/rte_atomic.h
> +++ b/lib/eal/include/generic/rte_atomic.h
> @@ -116,9 +116,13 @@
>   * Guarantees that operation reordering does not occur at compile time
>   * for operations directly before and after the barrier.
>   */
> +#ifndef RTE_TOOLCHAIN_MSVC
>  #define	rte_compiler_barrier() do {		\
>  	asm volatile ("" : : : "memory");	\
>  } while(0)
> +#else
> +#define rte_compiler_barrier() _ReadWriteBarrier()

Does this actually add a full memory barrier? If so, that's really not what we
want, and will slow things down.