Re: [PATCH 5/6] acl: make compatible with instruction set updates for MSVC

[Andre Muezerie <andremue@linux.microsoft.com>]

On Tue, Feb 25, 2025 at 09:03:37AM +0000, Bruce Richardson wrote:
> On Mon, Feb 24, 2025 at 01:01:18PM -0800, Andre Muezerie wrote:
> > Top level 'cc_avx2_flags' was created and holds the correct flags
> > depending on the compiler used.
> > 
> > File meson.build was updated to handle the correct AVX512 flags
> > depending on compiler used.
> > 
> > Signed-off-by: Andre Muezerie <andremue@linux.microsoft.com>
> > ---
> >  lib/acl/meson.build | 16 +++++++++-------
> >  1 file changed, 9 insertions(+), 7 deletions(-)
> > 
> > diff --git a/lib/acl/meson.build b/lib/acl/meson.build
> > index fefe131a48..24e47b6cc1 100644
> > --- a/lib/acl/meson.build
> > +++ b/lib/acl/meson.build
> > @@ -19,7 +19,7 @@ if dpdk_conf.has('RTE_ARCH_X86')
> >      avx2_tmplib = static_library('avx2_tmp',
> >              'acl_run_avx2.c',
> >              dependencies: static_rte_eal,
> > -            c_args: cflags + ['-mavx2'])
> > +            c_args: [cflags, cc_avx2_flags])
> >      objs += avx2_tmplib.extract_objects('acl_run_avx2.c')
> >  
> >      # compile AVX512 version if:
> > @@ -38,6 +38,12 @@ if dpdk_conf.has('RTE_ARCH_X86')
> >          # compiler flags, and then have the .o file from static lib
> >          # linked into main lib.
> >  
> > +        if is_ms_compiler
> > +            acl_avx512_args = cc_avx512_flags
> > +        else
> > +            acl_avx512_args = ['-mavx512f', '-mavx512vl', '-mavx512cd', '-mavx512bw']
> > +        endif
> > +
> 
> in the non-msvc case are these flags not the same as cc_avx512_flags too?
> If so, let's just get rid of the acl_avx512_args variable generally.
> 
> /Bruce

It's not an exact match. I did not look further to see if this was intentional or result
of a typo. TBH I'm not even sure if it would be possible to deduct this from the code.
Also, all the CPUs I have looked at bring all these 5 instruction sets together, but we
know this might not hold true in the future as each one of them has an independent CPUID flag.

    cc_avx512_flags = ['-mavx512f', '-mavx512vl', '-mavx512dq', '-mavx512bw']

My choice was to keep the flags that were used initially, but I can change that if the
maintainers tell me this was a mistake.