Thanks for the feedback. My apologies for delayed reply.
> -----Original Message-----
> From: Konstantin Ananyev <konstantin.v.anan...@yandex.ru>
> Sent: Sunday, August 7, 2022 5:56 PM
> To: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>; Amit Prakash
> Shukla <amitpraka...@marvell.com>
> Cc: dev@dpdk.org; Jerin Jacob Kollanukkaran <jer...@marvell.com>;
> sta...@dpdk.org; nd <n...@arm.com>
> Subject: [EXT] Re: [PATCH] ring: compilation fix with GCC-12
>
> External Email
>
> ----------------------------------------------------------------------
> 06/08/2022 19:35, Honnappa Nagarahalli пишет:
> > <snip>
> >
> >>
> >> GCC 12 raises the following warning:
> >>
> >> In function '__rte_ring_dequeue_elems_128',
> >> inlined from '__rte_ring_dequeue_elems' at
> >> ../lib/ring/rte_ring_elem_pvt.h:262:3,
> >> inlined from '__rte_ring_do_hts_dequeue_elem' at
> >> ../lib/ring/rte_ring_hts_elem_pvt.h:237:3,
> >> inlined from 'rte_ring_mc_hts_dequeue_bulk_elem' at
> >> ../lib/ring/rte_ring_hts.h:83:9,
> >> inlined from 'rte_ring_dequeue_bulk_elem' at
> >> ../lib/ring/rte_ring_elem.h:391:10,
> >> inlined from 'rte_ring_dequeue_elem' at
> >> ../lib/ring/rte_ring_elem.h:476:9,
> >> inlined from 'rte_ring_dequeue' at
> >> ../lib/ring/rte_ring.h:463:9,
> >> inlined from 'rxa_intr_ring_dequeue' at
> >> ../lib/eventdev/rte_event_eth_rx_adapter.c:1196:10:
> >> ../lib/ring/rte_ring_elem_pvt.h:234:25: error: 'memcpy' writing
> >> 32 bytes into a region of size 8 overflows the destination
> >> [-Werror=stringop-overflow=]
> >> 234 | memcpy((void *)(obj + i), (void *)(ring + idx), 32);
> >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>
> >> Replacing memcpy with rte_memcpy fixes the GCC-12 compilation issue.
> > Any reason why this replacement fixes the problem?
> > Do you have any performance numbers with this change?
> >
> >> Also it would be better to change to rte_memcpy as the function is
> >> called in fastpath.
> > On Arm platforms, memcpy in the later versions has the best performance.
>
> I agree with Honnappa, it is better to keep memcpy() here.
> Actually what is strange - why it ends up in
> __rte_ring_dequeue_elems_128() at all?
> Inside rxa_intr_ring_dequeue() we clearly doing: rte_ring_dequeue(), which
> should boil down to ___rte_ring_dequeue_elems_64().
> it should go to __rte_ring_dequeue_elems_128() at all.
I agree. After having close look and doing few experiments, ideally it should
not be going to __rte_ring_dequeue_elems_128().
Sizeof(in call of rte_ring_enqueue_elem) gets evaluated at compile time which
in this case it is evaluated to 8 bytes so
__rte_ring_dequeue_elems_128() shall not be in the path. Looks like more of a
gcc-12 bug.?
>
> Another q - is this warning happens only on arm platforms?
Warning is observed on x86 with build type as debug.
"meson --werror --buildtype=debug build"
>
> >
> >>
> >> Bugzilla ID: 1062
> >> Fixes: 1fc73390bcf5 ("ring: refactor exported headers")
> >> Cc: sta...@dpdk.org
> >>
> >> Signed-off-by: Amit Prakash Shukla <amitpraka...@marvell.com>
> >> ---
> >> lib/ring/rte_ring_elem_pvt.h | 18 ++++++++++--------
> >> 1 file changed, 10 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/lib/ring/rte_ring_elem_pvt.h
> >> b/lib/ring/rte_ring_elem_pvt.h index
> >> 83788c56e6..3d85b13333 100644
> >> --- a/lib/ring/rte_ring_elem_pvt.h
> >> +++ b/lib/ring/rte_ring_elem_pvt.h
> >> @@ -10,6 +10,8 @@
> >> #ifndef _RTE_RING_ELEM_PVT_H_
> >> #define _RTE_RING_ELEM_PVT_H_
> >>
> >> +#include <rte_memcpy.h>
> >> +
> >> static __rte_always_inline void
> >> __rte_ring_enqueue_elems_32(struct rte_ring *r, const uint32_t size,
> >> uint32_t idx, const void *obj_table, uint32_t n) @@ -97,20
> >> +99,20 @@ __rte_ring_enqueue_elems_128(struct rte_ring *r, uint32_t
> >> prod_head,
> >> const rte_int128_t *obj = (const rte_int128_t *)obj_table;
> >> if (likely(idx + n <= size)) {
> >> for (i = 0; i < (n & ~0x1); i += 2, idx += 2)
> >> - memcpy((void *)(ring + idx),
> >> + rte_memcpy((void *)(ring + idx),
> >> (const void *)(obj + i), 32);
> >> switch (n & 0x1) {
> >> case 1:
> >> - memcpy((void *)(ring + idx),
> >> + rte_memcpy((void *)(ring + idx),
> >> (const void *)(obj + i), 16);
> >> }
> >> } else {
> >> for (i = 0; idx < size; i++, idx++)
> >> - memcpy((void *)(ring + idx),
> >> + rte_memcpy((void *)(ring + idx),
> >> (const void *)(obj + i), 16);
> >> /* Start at the beginning */
> >> for (idx = 0; i < n; i++, idx++)
> >> - memcpy((void *)(ring + idx),
> >> + rte_memcpy((void *)(ring + idx),
> >> (const void *)(obj + i), 16);
> >> }
> >> }
> >> @@ -231,17 +233,17 @@ __rte_ring_dequeue_elems_128(struct rte_ring
> >> *r, uint32_t prod_head,
> >> rte_int128_t *obj = (rte_int128_t *)obj_table;
> >> if (likely(idx + n <= size)) {
> >> for (i = 0; i < (n & ~0x1); i += 2, idx += 2)
> >> - memcpy((void *)(obj + i), (void *)(ring + idx), 32);
> >> + rte_memcpy((void *)(obj + i), (void *)(ring + idx),
> 32);
> >> switch (n & 0x1) {
> >> case 1:
> >> - memcpy((void *)(obj + i), (void *)(ring + idx), 16);
> >> + rte_memcpy((void *)(obj + i), (void *)(ring + idx),
> 16);
> >> }
> >> } else {
> >> for (i = 0; idx < size; i++, idx++)
> >> - memcpy((void *)(obj + i), (void *)(ring + idx), 16);
> >> + rte_memcpy((void *)(obj + i), (void *)(ring + idx),
> 16);
> >> /* Start at the beginning */
> >> for (idx = 0; i < n; i++, idx++)
> >> - memcpy((void *)(obj + i), (void *)(ring + idx), 16);
> >> + rte_memcpy((void *)(obj + i), (void *)(ring + idx),
> 16);
> >> }
> >> }
> >>
> >> --
> >> 2.25.1
> >
