What's the current status of optimization passes for LLVM18/20?

[thetayloredman]

It is my understanding that LLVM's new pass builder does not expose its defaults (-O2 for example) through the C ABI until LLVM21. How is one meant to enable optimization passes considering there aren't even any passes to be added?

[gxtaillon]

It's possible to call module.run_passes("default<O3>", ...), I've used it since LLVM17 with good results.