On Wed, 16 Oct 2024 17:32:27 +0200
David Marchand <david.march...@redhat.com> wrote:
> On Wed, Oct 16, 2024 at 5:04 PM Stephen Hemminger
> <step...@networkplumber.org> wrote:
> >
> > On Wed, 16 Oct 2024 15:54:11 +0200
> > Mattias Rönnblom <mattias.ronnb...@ericsson.com> wrote:
> >
> > > Extend checkpatches.sh to detect the use of __builtin_(ffs|ffsll).
> > >
> > > These intrinsics are not available in MSVC, and there are perfectly
> > > serviceable alternatives in <rte_bitops.h>.
> > >
> > > Signed-off-by: Mattias Rönnblom <mattias.ronnb...@ericsson.com>
> > > Suggested-by: David Marchand <david.march...@redhat.com>
> >
> > Shouldn't this apply to all _builtin_ functions.
> >
> > There are a lot of drivers still doing this.
>
> - The updated check here is about use of __builtin_XXX instead of DPDK
> bit count ops.
> So when you refer to all builtin functions, there may be other
> builtins related to bit count we are missing, but at least the current
> patch is better than before.
>
>
> - On the larger topic of refusing *any* __builtin_, some use of them
> are "legit" under compiler checks.
> So the check would have to skip headers where wrappers are provided to
> the rest of DPDK.
> This seems possible, but a larger and probably more tricky change for now.
>
> Are you ok if we go with this patch as is, in a first step?
>
>
Examples of direct use of builtin
app/dumpcap/main.c: log2 = sizeof(size) * 8 - __builtin_clzl(size -
1);
app/test-dma-perf/benchmark.c:
__builtin_ia32_clflush(data + offset);
drivers/bus/fslmc/qbman/include/compat.h:#define likely(x)
__builtin_expect(!!(x), 1)
drivers/bus/fslmc/qbman/include/compat.h:#define unlikely(x)
__builtin_expect(!!(x), 0)
drivers/common/nfp/nfp_platform.h:#define __bf_shf(x)
(__builtin_ffsll(x) - 1)
drivers/crypto/ccp/ccp_dev.c: first_zero = __builtin_ffsl(~word);
app/test/test_memcpy_perf.c: if (__builtin_constant_p(n))
drivers/net/bonding/rte_eth_bond_pmd.c: if
(__builtin_popcountl(link_speeds) != 2) {
Think that direct use of __builitin_expect should be flagged.
And the lots of __builtin_in mlx5 should also be flagged.
