Expose function addresses as symbols to assembler

[ColdHeat]

Mac Build 1.0.272 Beta

Helpful for patching.

[psifertex]

Thanks -- we've definitely talked about doing that before and have some ideas how to do it, definitely agree it would be super handy.

[jeffli678]

To do this, we will need to do some basic parsing of the assembly, replace function names (or other similar stuff), with the actual address and send it to the assembler. Its definitely do-able, just need some time to write the code

[xusheng6]

For x86, yasm returns the unknown symbol, and we can replace it with its actual value. For LLVM MC, I am pretty sure the lexer can give us the same or even more information, which enables us to achieve the goal

[jonpalmisc]

It's worth noting that for LLVM MC backends (or at least for AArch64), attempts to use symbols actually just silently fail (and turn into spinning branches) rather than producing an error.