payload: refine payload expr merging

nf_tables can handle payload exprs for sizes <= sizeof(u32) via a direct
operation from the eval loop, rather than a a call to the payload
expression.  Two loads for four byte quantities are thus faster than a
single load for an 8 byte load.

ip saddr 1.2.3.4 ip daddr 2.3.4.5

is faster with this applied, even though it involves two payload and two
two compare expressions, just because all can be handled from the main
loop without any calls to expression ops.

Keep merging for linklayer and when at least one of the expressions
already exceeded the 4 byte "limit" anyway.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

0 files changed, 0 insertions, 0 deletions