Compiler: emit DWARF2 line number information

[vbgl]

Demo: when compiling the program below (jasminc -o crash.s crash.jazz && cc -o crash crash.s) and running it within gdb, here is the resulting output:

Program received signal SIGSEGV, Segmentation fault.
main () at crash.jazz:6
6         r = (u8)[end];

Here are the full contents of crash.jazz:

export
fn main(reg u64 argc argv) -> reg u8 {
  reg u64 end;
  reg u8 r;
  end = [argv + 8 * argc];
  r = (u8)[end];
  return r;
}

and the assembly listing produced by jasminc:

        .att_syntax
        .text
        .p2align        5
        .globl  _main
        .globl  main
_main:
main:
        .file 1 "crash.jazz"
        .loc 1 5 2
        movq    (%rsi,%rdi,8), %rax
        .loc 1 6 2
        movb    (%rax), %al
        ret

[vbgl]

I’ve just added a command line flag -g to turn ON this new feature. It is OFF by default.