Re: [PATCH v12 2/3] drivers/common: add diagnostics macros to make code portable

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

On Tue, Jan 14, 2025 at 08:27:17PM -0800, Andre Muezerie wrote:
> It was a common pattern to have "GCC diagnostic ignored" pragmas
> sprinkled over the code and only activate these pragmas for certain
> compilers (gcc and clang). Clang supports GCC's pragma for
> compatibility with existing source code, so #pragma GCC diagnostic
> and #pragma clang diagnostic are synonyms for Clang
> (https://clang.llvm.org/docs/UsersManual.html).
> 
> Now that effort is being made to make the code compatible with MSVC
> these expressions would become more complex. It makes sense to hide
> this complexity behind macros. This makes maintenance easier as these
> macros are defined in a single place. As a plus the code becomes
> more readable as well.
> 
> Signed-off-by: Andre Muezerie <andremue@linux.microsoft.com>
> ---
>  drivers/common/idpf/idpf_common_rxtx_avx512.c | 77 ++++++++++---------
>  1 file changed, 39 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/common/idpf/idpf_common_rxtx_avx512.c b/drivers/common/idpf/idpf_common_rxtx_avx512.c
> index b8450b03ae..fefc0a05ca 100644
> --- a/drivers/common/idpf/idpf_common_rxtx_avx512.c
> +++ b/drivers/common/idpf/idpf_common_rxtx_avx512.c
> @@ -6,10 +6,6 @@
>  #include "idpf_common_device.h"
>  #include "idpf_common_rxtx.h"
>  
> -#ifndef __INTEL_COMPILER
> -#pragma GCC diagnostic ignored "-Wcast-qual"
> -#endif
> -
>  #define IDPF_DESCS_PER_LOOP_AVX 8
>  #define PKTLEN_SHIFT 10
>  
> @@ -34,7 +30,7 @@ idpf_singleq_rearm_common(struct idpf_rx_queue *rxq)
>  			dma_addr0 = _mm_setzero_si128();
>  			for (i = 0; i < IDPF_VPMD_DESCS_PER_LOOP; i++) {
>  				rxp[i] = &rxq->fake_mbuf;
> -				_mm_store_si128((__m128i *)&rxdp[i].read,
> +				_mm_store_si128((__m128i *)RTE_IGNORE_CAST_QUAL(&rxdp[i].read),
>  						dma_addr0);
>  			}
>  		}

<SNIP for brevity>

Adding in the (void *) to the IGNORE macro will hugely reduce the amount of
casting being done in this file!

/Bruce