5 hours to compile macro, what can I do?

[dtolnay]

LLVM is not good at big functions, I have seen this before as well. One of the functions you are generating is almost 100,000 lines of Rust code including tons of internal control flow: starting here, repeated 300× in the definition of VANILLA_ID_MAP. You should reorganize define_blocks to break this one function up into 300 individual functions and it will compile in minutes.