DECODE_COMPACT_TERM is used pretty everywhere, so avoiding aggressive inlining might reduce performances quite a lot, so let's review this from 2 different point of views:

• Module loading: not very frequent, we do this just once every time a new module is called. On ESP32 code size isn't a big constraint, but reducing size on a less frequent situation might be good anyway.
• Execution: here performance are critical so we need to find a way to make inlining level tunable. On targets such as ESP32 I would keep aggressive inlining.

We have following options on the table:

• macro
• (always) inline function
• regular function

Open points:

is the compiler able to peform same kind of optimizations on both the "macro" and the "(always) inline function" scenario?

If no, we might do this:

#define DECODE_COMPACT_TERM_IMPL(...)

#ifdef OPTIMIZE_SIZE

void decode_compact_term(...) {
DECODE_COMPACT_TERM_IMPL
}

#define DECODE_COMPACT_TERM(...)
decode_compact_term(...)

#else

#define DECODE_COMPACT_TERM(...)
DECODE_COMPACT_TERM_IMPL(...)

#endif

I'll investigate the real impact on the 2 scenarios for execution.