[PATCH v5 02/39] eal: redefine macro to be integer literal for MSVC

[Tyler Retzlaff]

On Mon, Feb 26, 2024 at 12:51:38PM +0000, Konstantin Ananyev wrote:
> 
> 
> > MSVC __declspec(align(#)) is limited and accepts only integer literals
> > as opposed to constant expressions. define XMM_SIZE to be 16 instead of
> > sizeof(xmm_t) and static_assert that sizeof(xmm_t) == 16 for
> > compatibility.
> > 
> > Signed-off-by: Tyler Retzlaff <roretzla at linux.microsoft.com>
> > Acked-by: Morten Brørup <mb at smartsharesystems.com>
> > ---
> >  lib/eal/x86/include/rte_vect.h | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/lib/eal/x86/include/rte_vect.h b/lib/eal/x86/include/rte_vect.h
> > index a1a537e..441f1a0 100644
> > --- a/lib/eal/x86/include/rte_vect.h
> > +++ b/lib/eal/x86/include/rte_vect.h
> > @@ -11,6 +11,7 @@
> >   * RTE SSE/AVX related header.
> >   */
> > 
> > +#include <assert.h>
> >  #include <stdint.h>
> >  #include <rte_config.h>
> >  #include <rte_common.h>
> > @@ -33,9 +34,11 @@
> > 
> >  typedef __m128i xmm_t;
> > 
> > -#define	XMM_SIZE	(sizeof(xmm_t))
> > +#define	XMM_SIZE	16
> >  #define	XMM_MASK	(XMM_SIZE - 1)
> > 
> > +static_assert(sizeof(xmm_t) == 16, "");
> 
> I think it is better be:
> static_assert(sizeof(xmm_t) == XMM_SIZE, "");
> 

ack, will fix

> 
> BTW, is there any chance that in future versions MSVC would accept align(<constant_expression>)?

it does seem an oversight. i will ask the msvc team if they would like to enhance it.

thanks

> 
> > +
> >  typedef union rte_xmm {
> >  	xmm_t    x;
> >  	uint8_t  u8[XMM_SIZE / sizeof(uint8_t)];
> > --
> > 1.8.3.1
>