[LLVMdev] Debugging LLVM IR with GDB

[Duncan Sands]

Hi Pablo,

> Has anybody debugged LLVM IR with GDB? I'm using dragonegg to transform C into
> IR, then applying my optimizations. Passing "-g" to dragonegg doesn't seem to
> work since it generates debug info for the C code, not the IR. I really need GDB
> (lli doesn't solve my problems) in order to debug multi-threaded and
> multi-process MPI code.
>
> More clearly, if I have a file hello.ll and I execute:
>
> $> llc hello.ll -march=x86-64 -o hello.s
> $> mpicc -O0 hello.s -o hello
>
> Can I debug "hello" with GDB at the IR level? If so, how? If not, would it be
> possible to add debug info generation at the IR level (and how much effort
> required)? I read something about DwarfDebug but it's not clear to me how to use
> it or even if it does what I need. I hope I didn't miss any obvious solution.

it would be great to have a utility that, given an IR file, adds location debug
info to each line of it, the location being the line number within the IR file.
Then in the debugger you would get to see yourself moving around in the IR file
as you step through the program built from it.  Unfortunately I have no idea how
to implement this in a reasonable way.

Ciao, Duncan.