diff mbox series

[2/3] lpm: fix xmm_t casting for C++ in scalar version

Message ID 20220609121701.716299-3-kda@semihalf.com (mailing list archive)
State Accepted, archived
Delegated to: David Marchand
Headers
Series Fix xmm_t to rte_xmm_t scalar conversion |

Checks

Context Check Description
ci/checkpatch success coding style OK

Commit Message

Stanislaw Kardach June 9, 2022, 12:17 p.m. UTC 
  rte_xmm_t is a union type which wraps around xmm_t and maps its contents
to scalar structures. Since C++ has stricter type conversion rules than
C, the rte_xmm_t::x has to be used instead of C-casting.

The generated assembly is identical to the code without the fix (checked
both on x86 and RISC-V).

Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
---
 lib/lpm/rte_lpm_scalar.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Comments

David Marchand June 13, 2022, 9:29 a.m. UTC | #1 
On Thu, Jun 9, 2022 at 2:17 PM Stanislaw Kardach <kda@semihalf.com> wrote:
>
> rte_xmm_t is a union type which wraps around xmm_t and maps its contents
> to scalar structures. Since C++ has stricter type conversion rules than
> C, the rte_xmm_t::x has to be used instead of C-casting.
>
> The generated assembly is identical to the code without the fix (checked
> both on x86 and RISC-V).

Fixes: 406937f89ffd ("lpm: add scalar version of lookupx4")

>
> Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>


> ---
>  lib/lpm/rte_lpm_scalar.h | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/lib/lpm/rte_lpm_scalar.h b/lib/lpm/rte_lpm_scalar.h
> index f0d9f37894..161b40ff80 100644
> --- a/lib/lpm/rte_lpm_scalar.h
> +++ b/lib/lpm/rte_lpm_scalar.h
> @@ -15,18 +15,19 @@ extern "C" {
>
>  static inline void
>  rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
> -               uint32_t defv)
> +                uint32_t defv)

Nit: unrelated whitespace change.
Besides, indent is supposed to be one tab.
This can be dropped when applying.
diff mbox series

Patch

diff --git a/lib/lpm/rte_lpm_scalar.h b/lib/lpm/rte_lpm_scalar.h
index f0d9f37894..161b40ff80 100644
--- a/lib/lpm/rte_lpm_scalar.h
+++ b/lib/lpm/rte_lpm_scalar.h
@@ -15,18 +15,19 @@  extern "C" {
 
 static inline void
 rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
-		uint32_t defv)
+		 uint32_t defv)
 {
+	rte_xmm_t xip = { .x = ip };
 	uint32_t nh;
 	int ret;
 
-	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[0], &nh);
+	ret = rte_lpm_lookup(lpm, xip.u32[0], &nh);
 	hop[0] = (ret == 0) ? nh : defv;
-	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[1], &nh);
+	ret = rte_lpm_lookup(lpm, xip.u32[1], &nh);
 	hop[1] = (ret == 0) ? nh : defv;
-	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[2], &nh);
+	ret = rte_lpm_lookup(lpm, xip.u32[2], &nh);
 	hop[2] = (ret == 0) ? nh : defv;
-	ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[3], &nh);
+	ret = rte_lpm_lookup(lpm, xip.u32[3], &nh);
 	hop[3] = (ret == 0) ? nh : defv;
 }