Re: [dpdk-dev] [PATCH 1/2] net/ice: fix build error on lower version GCC

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Nov 03, 2020 at 08:56:28PM +0800, Leyi Rong wrote:
> Fix the build error when -march=skylake-avx512 is not supported on
> lower version GCC.
> 
> Fixes: ef5d52dae5e2 ("net/ice: add AVX512 vector path")
> 
> Signed-off-by: Leyi Rong <leyi.rong@intel.com>
> ---
>  drivers/net/ice/meson.build | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ice/meson.build b/drivers/net/ice/meson.build
> index 7d54a49236..ec8933aa1a 100644
> --- a/drivers/net/ice/meson.build
> +++ b/drivers/net/ice/meson.build
> @@ -46,12 +46,21 @@ if arch_subdir == 'x86'
>  
>  	if ice_avx512_cpu_support == true or ice_avx512_cc_support == true
>  		cflags += ['-DCC_AVX512_SUPPORT']
> -		ice_avx512_lib = static_library('ice_avx512_lib',
> -				      'ice_rxtx_vec_avx512.c',
> -				      dependencies: [static_rte_ethdev,
> -					static_rte_kvargs, static_rte_hash],
> -				      include_directories: includes,
> -				      c_args: [cflags, '-march=skylake-avx512', '-mavx512f', '-mavx512bw'])
> +		if cc.has_argument('-march=skylake-avx512')
> +			ice_avx512_lib = static_library('ice_avx512_lib',
> +					      'ice_rxtx_vec_avx512.c',
> +					      dependencies: [static_rte_ethdev,
> +						static_rte_kvargs, static_rte_hash],
> +					      include_directories: includes,
> +					      c_args: [cflags, '-march=skylake-avx512', '-mavx512f', '-mavx512bw'])
> +		else
> +			ice_avx512_lib = static_library('ice_avx512_lib',
> +					      'ice_rxtx_vec_avx512.c',
> +					      dependencies: [static_rte_ethdev,
> +						static_rte_kvargs, static_rte_hash],
> +					      include_directories: includes,
> +					      c_args: [cflags, '-mavx512f', '-mavx512bw'])
> +		endif

Rather than duplicating the whole static_library call, you can just do:
	avx512_cflags = [cflags, '-mavx512f', '-mavx512bw']
	if cc.has_argument('-march=skylake-avx512')
		avx512_cflags += '-march=skylake-avx512'
	endif

and then use avx512_cflags inside a single static_library call. Much
shorter code.

/Bruce

>  		objs += ice_avx512_lib.extract_objects('ice_rxtx_vec_avx512.c')
>  	endif
>  endif
> -- 
> 2.17.1
>