Re: speed of Lua/LPeg parsers

[Roberto Ierusalimschy <roberto@...>]

> This reminds me of something I was wondering about: could a special
> version of LPeg be created that takes direct advantage of LuaJIT
> acceleration, so that the "bytecode" of the PEG patterns itself gets
> JITtered? Does LuaJIT support (even conceptually, if not at this
> precise point in the beta) external C modules that have
> JIT-specialised functions, like the functions in the standard Lua
> modules are? If so, would it be possible for a single dynamically
> linked library to contain both the standard and JIT versions, or would
> they need to be separate? Or is this all a blind alley, and the only
> realistic way would be a port of LPeg to Lua itself?

Some time ago we implemented a simple JIT for LPeg. That JIT was
orders of magnitude simpler than LuaJIT, both because LPeg code
is much simpler than Lua code and because our JIT did not perform
any extra optimization: It uses a fixed translation for each LPeg
instruction. The end result was around three times faster than the
original.

-- Roberto