Strengthen ICF hash

Andi Kleen andi@firstfloor.org
Wed Mar 4 13:20:00 GMT 2015


Hi Honza,

Regarding modern hash functions, as far as I understand the trend
is to just stop doing anything fancy and just use the CRC instructions
in modern CPUs (unless you need a somewhat cryto hash to guard against
DoS attacks). spooky doesn't do that though, it's just a highly
optimized classical hash. It's much more stream lined than the somewhat
weird iterative hash construction that standard gcc uses, and I suspect
has better avalance effect. Also it'll do much less work per bit
(at the cost of larger code)

> Said all that I would be very curious if actual stronger hading would help.
> I saw some miscompares for stuff that should be covered by hash. I will try
> to get some stats soon.

I sent you the spooky patches in separate mail. I did a quick test run
and they don't seem to regress anything.

-Andi



More information about the Gcc-patches mailing list