[Bug debug/70578] internal compiler error: in output_index_string, at dwarf2out.c with -gsplit-dwarf

[ishikawa at yk dot rim.or.jp]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70578

--- Comment #8 from ishikawa,chiaki <ishikawa at yk dot rim.or.jp> ---
As for gcc-5 ICE, I observe an important thing after a little experimentation.

This is a shortened command line that causes the ICE.

 /usr/bin/gcc-5 -std=gnu99 -o vp9_dsubexp.o -c -DNDEBUG=1 -DTRIMMED=1 \
 -DHAVE_CONFIG_H=vpx_config.h -fPIC -DMOZILLA_CLIENT                  \
 -fno-builtin-strlen -Wl,--gdb-index -Dfdatasync=fdatasync            \
 -DDEBUG_4GB_CHECK -DUSEHELGRIND=1                \
 -gsplit-dwarf -g3 -Og ./vp9_dsubexp.i

If I remove -gsplit-dwarf, I don't get the ICE.


ishikawa@debian-vbox-ci:/tmp$  /usr/bin/gcc-5 -std=gnu99 -o vp9_dsubexp.o -c
-DNDEBUG=1 -DTRIMMED=1 \
 -DHAVE_CONFIG_H=vpx_config.h -fPIC -DMOZILLA_CLIENT                  \
 -fno-builtin-strlen -Wl,--gdb-index -Dfdatasync=fdatasync            \
 -DDEBUG_4GB_CHECK -DUSEHELGRIND=1                \
 -g3 -Og ./vp9_dsubexp.i
> > > > ishikawa@debian-vbox-ci:/tmp$ 

But then, leaving -gsplit-dwarf intact, if I change "-g3" to "-g", I don't get
an ICE.

ishikawa@debian-vbox-ci:/tmp$ /usr/bin/gcc-5 -std=gnu99 -o vp9_dsubexp.o -c
-DNDEBUG=1 -DTRIMMED=1 \
 -DHAVE_CONFIG_H=vpx_config.h -fPIC -DMOZILLA_CLIENT                  \
 -fno-builtin-strlen -Wl,--gdb-index -Dfdatasync=fdatasync            \
 -DDEBUG_4GB_CHECK -DUSEHELGRIND=1                \
 -gsplit-dwarf -g -Og ./vp9_dsubexp.i
> > > > ishikawa@debian-vbox-ci:/tmp$ 

So it could be a combination of -gsplit-dwarf and -g3 in my GCC-5 case.
I have no idea what the cause of ICE for G++-6 case, though.

TIA