The compiler is failing to draw the connection between
slice cap and slice len, so is missing some obvious BCE opportunities.
Give it a hint by making the cap equal to the length.
The generated code is smaller and cleaner, and a bit faster.
name old time/op new time/op delta
Decode/tcp4-8 12.2ns ± 1% 11.6ns ± 3% -5.31% (p=0.000 n=28+29)
Decode/tcp6-8 12.5ns ± 2% 11.9ns ± 2% -4.84% (p=0.000 n=30+30)
Decode/udp4-8 11.5ns ± 1% 11.1ns ± 1% -3.11% (p=0.000 n=25+24)
Decode/udp6-8 11.8ns ± 3% 11.4ns ± 1% -3.08% (p=0.000 n=30+26)
Decode/icmp4-8 11.0ns ± 3% 10.6ns ± 1% -3.38% (p=0.000 n=25+30)
Decode/icmp6-8 11.4ns ± 1% 11.1ns ± 2% -2.29% (p=0.000 n=27+30)
Decode/igmp-8 10.3ns ± 0% 10.0ns ± 1% -3.26% (p=0.000 n=19+23)
Decode/unknown-8 8.68ns ± 1% 8.38ns ± 1% -3.55% (p=0.000 n=28+29)
Josh Bleecher SnyderandJosh Bleecher Snyder
efad55cf86