Racket now available on Compiler Explorer

[jryans]

@samth

Few of the PLT_ flags control optimization. Are there particular ones you are interested in?

Ah yeah, I guess most of them are for printing diagnostic output, like PLT_LINKLET_SHOW and friends. I may have mentally bucketed the CS Compilation Modes as controlling "optimisation", but after looking again, those are mainly selecting e.g. interpreter vs. machine code and such.

Are there other optimisation settings that would be interesting to try?

Even if they aren't really about optimisation, it may still be convenient to wire up the PLT_* flags on Compiler Explorer, as there's a button to show the output the toolchain printed during compilation. This could be used as a cheap way of viewing things like the PLT_LINKLET_SHOW output until a more polished UI is added.

@samth

For correlating to source lines, I think this would be a really big win for Racket, but is as you say a significant challenge. A lot of infrastructure is already there to do this, but it would take significant integration work. I think there are two major ways you could go about this:

• Emitting debug information using an existing format (eg DWARF).
• Printing out something along with the assembly code and then correlating that back.

The second would probably be less work in Chez Scheme itself but more work in the external tooling and is probably where I would start.

Thanks for these hints! It helps to have confirmation that my (very rough) understanding of Racket's debug info handling was mostly correct.

My ongoing research is focused on reliable debug info, and I think it could be quite fun to add some level of debug info support to Racket, so I'll keep exploring what's possible here. I'd really like to try aiming for stronger guarantees of debug info correctness than you typically get with other toolchains, but perhaps I should start with making a basic version work first.