[dpdk-dev] [PATCH 1/8] lpm: Fix pointer aliasing issues

[Bruce Richardson]

On Thu, Feb 25, 2016 at 01:48:34PM -0500, Aaron Conole wrote:
> The current implementation attempts to use a uint16_t to alias the lpm table
> structures. Such aliasing can break optimizer performance. This patch uses
> union type indirection and adds static inline functions for performing the
> aliasing.
> 
> Signed-off-by: Aaron Conole <aconole at redhat.com>
> ---
>  lib/librte_lpm/rte_lpm.h | 53 +++++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 41 insertions(+), 12 deletions(-)
> 
> diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h
> index c299ce2..eae6ff1 100644
> --- a/lib/librte_lpm/rte_lpm.h
> +++ b/lib/librte_lpm/rte_lpm.h
> @@ -157,6 +157,33 @@ struct rte_lpm {
>  };
>  
>  /**
> + * Convert from tbl_entry types to integer types
> + */
> +static inline uint16_t
> +rte_lpm_tbl24_entry_to_uint16(const struct rte_lpm_tbl24_entry *entry)
> +{
> +	union {
> +		uint16_t                   i;
> +		struct rte_lpm_tbl24_entry s;
> +	} tbl_entry_u;
> +
> +	tbl_entry_u.s = *entry;
> +	return tbl_entry_u.i;
> +}
> +
> +static inline uint16_t
> +rte_lpm_tbl8_entry_to_uint16(const struct rte_lpm_tbl8_entry *entry)
> +{
> +	union {
> +		uint16_t                  i;
> +		struct rte_lpm_tbl8_entry s;
> +	} tbl_entry_u;
> +
> +	tbl_entry_u.s = *entry;
> +	return tbl_entry_u.i;
> +}
> +

These two new functions could be reduced to one with the help of patch:
http://dpdk.org/dev/patchwork/patch/9087/

Anyone care to go back and review or ack that patch for me and simplify all
the lpm code just that little bit?

/Bruce