How to disable import optimization?

[petrihakkinen]

This may be a silly question or XY problem, but is there some way to disable import optimization for all globals (without listing them all explicitly in compile options)? I'm missing being able to monkey patch global functions, which has been a very useful debugging method in the past. I understand there are security and performance considerations, but this would only be used for debugging.

[zeux]

Setting optimizationLevel to 0 in CompileOptions would do this.

[zeux]

I guess I should also mention that lua_setsafeenv to false will have a similar effect but will work at runtime, which may be preferable as you can conditionally activate it during debugging without recompiling. This needs to be done per thread of execution. Needless to say both options have a performance impact.

[petrihakkinen]

lua_setsafeenv seems to be exactly what I'm looking for. Thank you!

Out of curiosity, does it deoptimize by patching the compiled bytecode, or how does it work?

[zeux]

Interpreter validates safeenv status before running certain instructions; this results in GETIMPORT falling back to running global lookup explicitly without assuming cached imports are valid, and various FASTCALL instructions using the special fallback bytecode that exists anyway to handle complex cases that interpreter builtins by itself don't handle. So it doesn't require runtime patching of bytecode but it does rely on special code inside interpreter or special bytecode generated by the compiler.

[petrihakkinen]

That's a very nice solution indeed.