Re: [ANN] LuaJIT-2.0.0-beta8
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- Subject: Re: [ANN] LuaJIT-2.0.0-beta8
- From: Josh Haberman <jhaberman@...>
- Date: 2011年6月23日 19:24:49 +0000 (UTC)
Mike Pall <mikelu-1106 <at> mike.de> writes:
> For the bytecode I'm already delta-encoding most values and use a
> couple of other tricks to reduce their range. So the majority of
> values for the ULEB128 encoding fit into 0-127 and only need a
> single byte. Then it _is_ faster to do this:
>
> v = *p++;
> if (LJ_UNLIKELY(v >= 0x80)) { ... decode the remaining bytes ... }
> return v
The scheme I mentioned has exactly the same encoding for values
0-127, so the code for the 1-byte case could be identical. The only
difference is for multi-byte values (ie. the "...decode the remaining
bytes..." part.)
But if it's extremely rare to have values of more than one or two
bytes, it probably won't make a difference in the end.
Josh