[dev] JIT & VM discussion

From: Connor Lane Smith <cls_AT_lubutu.com>
Date: Sat, 18 Jun 2016 10:33:23 +0100

Hi all,

I was wondering if others had an opinion on JIT. Suppose we don't need
anything fancy like adaptive optimisation, but just wanted to compile
a program at runtime. One possibility might be to generate C code and
store that in a file and then call the C compiler and then execute the
resulting binary... But that seems a bit unpleasant, prone to
compilation failure, and not particularly lightweight either.

One solution could be simply to produce assembly code, but then that
is tied to a specific architecture, which is unfortunate. There's also
LLVM, but that is a very big and complicated dependency, which
shouldn't really be necessary if we're just jitting something quickly
and don't mind it being a little unoptimised for the sake of
simplicity and speed of compilation. We just want to portably generate
machine code and then run it.

An ideal might be something like an abstract instruction set together
with a JIT for the abstract machine. To be honest a JIT might not even
be necessary so long as it is has very little interpretation overhead,
the instruction set is general purpose and fixed, and it plays well
with the C memory model.

Does anyone have any ideas?

Thanks,
cls
Received on Sat Jun 18 2016 - 11:33:23 CEST