qemu

I was curious, so I looked into it. - TCG = Tiny Code Generator; QEMU's framework for emulating CPU architectures via translating instructions[1] - TCI = Tiny Code Interpreter? The source code says: "(TCG with bytecode interpreter, experimental and slow)"[2] - TCTI = Tiny Code Threaded-Dispatch Interpreter? The source code says: "TCTI (TCG with threaded-dispatch bytecode interpreter, experimental and slow; but faster than TCI)"[3] So, apparently, it's some kind of optimized interpreter. Exactly what it means by "threaded-dispatch" is unclear, there's some surprisingly tricky looking things going on[4]. Does threaded refer to OS threading, or does it maybe mean that it's doing something a bit more like a cached interpreter? I wonder if it's even more clever than that. [1]: https://wiki.qemu.org/Documentation/TCG [2]: https://github.com/tct

It's a backend for qemu's cpu JIT that doesn't actually JIT code for the host CPU, but code that's simply more performant to interpret than the target CPU arch as a set of JOP/ROP gadgets. It's so it works as perfomantly as possible without in case without the ability to set pages executable like on iOS. https://github.com/tctiSH/qemu/blob/with_tcti_vectors/tcg/aa...