[Bug target/82005] [8 regression] early lto debug creates invalid assembly on Darwin

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82005

--- Comment #8 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 30 Aug 2017, dominiq at lps dot ens.fr wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82005
> 
> --- Comment #7 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> With the patch in comment 6, compiling the test in comment 0 with -g -flto
> gives
> 
> while processing
> /var/folders/8q/sh_swgz96r7f5vnn08f7fxr00000gn/T//ccqniUp8.ltrans0.ltrans.o:
> warning: could not find referenced DIE
> while processing
> /var/folders/8q/sh_swgz96r7f5vnn08f7fxr00000gn/T//ccqniUp8.ltrans0.ltrans.o:
> warning: could not find referenced DIE
> while processing
> /var/folders/8q/sh_swgz96r7f5vnn08f7fxr00000gn/T//ccqniUp8.ltrans0.ltrans.o:
> warning: could not find referenced DIE
> while processing
> /var/folders/8q/sh_swgz96r7f5vnn08f7fxr00000gn/T//ccqniUp8.ltrans0.ltrans.o:
> warning: could not find referenced DIE

I guess that's expected given the missing implementation of simple-objects
copy_lto_debug_sections for Mach-O.

If you manually do the extraction / renaming and link with the early
debug part it should work(?)  (I didn't try myself, doing this
manually might be a bit tricky -- look at the compile assembler,
remove the DWARF segment and rename the GNU_DWARF_LTO segment to
DWARF, remove all text and data sections and assemble.