fix: remove unnecessary hash calculations

[jrandolf]

No description provided.

[marijnh]

What's the reasoning behind this change? The extra shift and add won't actually be expensive, and I've often seen this pattern (with a bitshift on both values) in simple hash functions.

[jrandolf]

I don't see the reason why both values are bit shifted. The depth is already bit shifted (<< 0) and the parent just bit shifts to allocate for the maximal depth (in this case, 2^8).

[Edit]: We also need to modulo the parent hash with some prime to truncate for later, but this hash holds for at least 16 or so indents without overflowing.

[marijnh]

I don't know a lot about hash functions, but running a simulation on hashing groups of small integers this change increases the amounts of clashes by about 30%, so I don't think it's a good idea.