[LLVMdev] unwind's permanent residence

[Renato Golin]

On 30 January 2015 at 20:43, Jonathan Roelofs <jonathan at codesourcery.com> wrote:
> Last time we brought this up, there was only partial consensus, and then
> someone arbitrarily declared total consensus (without compelling arguments
> in any particular direction) that we were going to move it to compiler_rt.
> Then the discussion fell on the floor because no-one had time to actually do
> the move. Please, let's not let that happen again this time.

So, do we have a consensus?

AFAICS, the most agree solution (with optionals to be defined):

1. Move Unwinder to its own repository in the LLVM server
2. Make the CMake connections from libc++abi and compiler-rt
  2.1 OPTIONAL 1: err if libunwinder is not there, clang errs if rtlib=RT
  2.2 OPTIONAL 2: warns if libunwind is not there, clang errs if rtlib=RT
  2.3 OPTIONAL 3: nothing, make clang smarter to pick existing unwinder
3. Change clang to assume -lunwind when --rtlib=compiler-rt
  3.1 OPTIONAL 4: allow linker error if no -lunwind / -lgcc_s
  3.2 OPTIONAL 5: Add option to change unwinder library by not adding
-lunwind/-lgcc_s, but whatever comes as argument

1, 2, and 3 must be changed.

I vote for adding { 2.2, 3.1 } for now, { 2.2, 3.1, 3.2 } for later.

My idea for 3.2 is something like --unwinder=libgcc_s / libunwind, or
something like that.

I personally don't think the front-end scanning existing libraries is
a good thing to do, but I'm not against the idea, if anyone feels
strongly about it.

If all of us could agree to a common solution, and make sure all
interested parties are in, we should do the move before 3.7.

Please, cast your votes.

cheers,
--renato