Heads-Up: early LTO debug to land, breaking Mach-O / [X]COFF

[Richard Biener]

On Fri, 12 May 2017, Richard Biener wrote:

> 
> This is a heads-up that I am in the process of implementing the last
> of Jasons review comments on the dwarf2out parts of early LTO debug
> support.  I hope to post final patches early next week after thoroughly
> re-testing everything.
> 
> Note that Mach-O and [X]COFF support in the simple-object machinery
> is still missing for the early LTO debug feature so I am going to
> break LTOing with DWARF debuginfo on Darwin and Windows (CCing
> maintainers).  Mach-O support has been worked on a bit by Iain
> and myself but the simple-object piece is still missing.
> A workaround is to use stabs on these targets with LTO.
> 
> DWARF part: https://gcc.gnu.org/ml/gcc-patches/2016-11/msg01023.html
> simple-object part: 
> https://gcc.gnu.org/ml/gcc-patches/2016-10/msg01733.html
> 
> both still apply with some fuzz.

The patches have been applied now (r251220).  You'll see -flto -g
testcases on the above archs fail (I'm still curious how exactly).
There's going to be a "workaround" I plan to apply no earlier than
stage3, it will effectively force -g0 on those targets when you
use DWARF.

Seeing the FAILs might be enough hunch to look into the (small)
task of implementing the simple-object implementation of
simple_object_copy_lto_debug_sections for your object format.

Richard.