[dpdk-dev] [PATCH v2 3/6] fib: introduce AVX512 lookup

[Bruce Richardson]

On Thu, May 14, 2020 at 01:28:27PM +0100, Vladimir Medvedkin wrote:
> Add new lookup implementation for DIR24_8 algorithm using
> AVX512 instruction set
> 
> Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin at intel.com>
> ---
<snip>
> diff --git a/lib/librte_fib/meson.build b/lib/librte_fib/meson.build
> index 771828f..86b1d4a 100644
> --- a/lib/librte_fib/meson.build
> +++ b/lib/librte_fib/meson.build
> @@ -5,3 +5,13 @@
>  sources = files('rte_fib.c', 'rte_fib6.c', 'dir24_8.c', 'trie.c')
>  headers = files('rte_fib.h', 'rte_fib6.h')
>  deps += ['rib']
> +
> +if dpdk_conf.has('RTE_ARCH_X86')
> +	if cc.has_argument('-mavx512f')
> +		cflags += '-DCC_AVX512_SUPPORT'
> +		cflags += '-mavx512f'
> +	endif
> +	if cc.has_argument('-mavx512dq')
> +		cflags += '-mavx512dq'
> +	endif
> +endif

This will likely break the FIB library for systems which don't have AVX-512
support, since you are enabling AVX-512 for the whole library, meaning that
the compiler can put AVX-512 instructions anywhere it wants in the library.
You need to separate out the AVX-512 code into a separate file, and compile
that file - and only that file - for AVX-512. An example of how this should
be done, can be seen in the AVX support in the i40e net driver.

Regards,
/Bruce