IA-16: initial DWARF2 support

[asiekierka]

This PR technically fixes #38 - but without a way to use it in a DOS debugger, it is arguably of little use on its own. I have worked on it for two reasons:

• Even addr2line-level line number and symbol information could be of potential use to WonderSwan emulators, which do not have any defined debugging format at this time;
• Newer GCC versions make it increasingly harder to disable debug output for a target without things breaking, so it'd be good to at least have partial debug symbol support before attempting an update again.

It does not provide call frame/unwind information - only symbol and line number information is provided, and even then, something seems broken. The matching binutils-ia16 PR is required.

[asiekierka]

The DWARF2 line number information support works fine, but not for segelf - it seems that something in the process ends up modifying the offset so that the address 0x0 in the line number information starts at the end of the program. I suspect it's related to tkchia/binutils-ia16#6

[asiekierka]

I've figured it out. The GCC side is fine; it's the Binutils side which needs a workaround, I'll document it more on that PR.

As such, I am (finally) un-drafting the PR. Sorry for taking so long.

[ppsilv]

You are adding a new support to this project but it does not compile, how did you do that?

[asiekierka]

Compiles on my machine just fine (both using latest Arch Linux and Alpine Linux).

[ppsilv]

Compiles on my machine just fine (both using latest Arch Linux and Alpine Linux).

This is the best statement of bad developers "IN MY MACHINE WORKS...".
When I develop I say works in all machines of the world.

[asiekierka]

You're trying to compile a GCC version from eight years ago, which has not been maintained in almost a year. I distribute binary builds as part of my project, but these are fine-tuned to target the WonderSwan and do not have everything necessary to compile standard DOS programs, which is why I did not recommend it. Nevertheless, here are my build scripts.

[asiekierka]

If you're trying to build gcc-ia16, it has official build scripts available: https://codeberg.org/tkchia/build-ia16