> there's the brute-force approach of simply embedding textual macro definitions. That might be good enough for most use cases in practice
I very much want this for usage from Rust, so that doesn't suffice.
> It might be possible to do something similar for BTF. As output format, either add a new 'constant integer' node
That sounds promising to me, for the common case.
> Edit: Forgot to mention – functional macros would be nice too, but of course they're much harder to translate. And heck, what about inline functions? Convert them to BPF?
In an ideal world, 1) emit a symbol for them so they can be used from any language, albeit not "inline", and 2) compile them to bytecode that LTO can incorporate and optimize, for languages using the same linker.
Neither of those would work for macros designed for especially unusual usages that can't possibly work as functions. (The two most common cases I can think of: macros that accept names and use them as lvalues, and macros that emit partial syntax such as paired macros emitting unmatched braces.) But honestly, flagging those and handling all the common cases via BTF information would still be a huge improvement.
Perhaps we should continue this on an IRLO thread?
I very much want this for usage from Rust, so that doesn't suffice.
> It might be possible to do something similar for BTF. As output format, either add a new 'constant integer' node
That sounds promising to me, for the common case.
> Edit: Forgot to mention – functional macros would be nice too, but of course they're much harder to translate. And heck, what about inline functions? Convert them to BPF?
In an ideal world, 1) emit a symbol for them so they can be used from any language, albeit not "inline", and 2) compile them to bytecode that LTO can incorporate and optimize, for languages using the same linker.
Neither of those would work for macros designed for especially unusual usages that can't possibly work as functions. (The two most common cases I can think of: macros that accept names and use them as lvalues, and macros that emit partial syntax such as paired macros emitting unmatched braces.) But honestly, flagging those and handling all the common cases via BTF information would still be a huge improvement.
Perhaps we should continue this on an IRLO thread?