Re: [dpdk-dev] [PATCH v2] build: fix SVE compile error with gcc8.3

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

On Thu, May 20, 2021 at 07:40:12PM +0800, Chengwen Feng wrote:
> If the target machine has SVE feature (e.g. "-march=armv8.2-a+sve'),
> and the compiler is gcc8.3, it will compile error:
> 	In file included from ../dpdk-next-net/lib/eal/common/
> 	eal_common_options.c:38:
> 	../dpdk-next-net/lib/eal/arm/include/rte_vect.h:13:10: fatal
> 	error: arm_sve.h: No such file or directory
> 	#include <arm_sve.h>
> 	       ^~~~~~~~~~~
> 	compilation terminated.
> 
> The root cause is that gcc8.3 support SVE (the macro __ARM_FEATURE_SVE
> was 1), but it doesn't support SVE ACLE [1].
> 
> The solution:
> a) Detect compiler whether support SVE ACLE, if support then define
> CC_SVE_ACLE_SUPPORT macro.
> b) Use the CC_SVE_ACLE_SUPPORT macro to include SVE header file.
> 
> [1] ACLE:  Arm C Language Extensions, the SVE ACLE header file is
> <arm_sve.h>, user should include it when writing ACLE SVE code.
> 
> Fixes: 67b68824a82d ("lpm/arm: support SVE")
> 
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> ---
> v2: 
> * modify title start with 'build'
> 

One minor comment inline below.
/Bruce
> ---
>  config/arm/meson.build         | 5 +++++
>  lib/eal/arm/include/rte_vect.h | 2 +-
>  lib/lpm/rte_lpm.h              | 2 +-
>  3 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build
> index e83a56e..bff70e4 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -480,6 +480,11 @@ if (cc.get_define('__ARM_NEON', args: machine_args) != '' or
>      compile_time_cpuflags += ['RTE_CPUFLAG_NEON']
>  endif
>  
> +if (cc.get_define('__ARM_FEATURE_SVE', args: machine_args) != '' and
> +    cc.check_header('arm_sve.h'))
Please double-indent this line. It looks like part of the condition body
as-is.