[Bug lto/81968] [8 regression] early lto debug objects make Solaris ld SEGV

[ro at CeBiTec dot Uni-Bielefeld.DE]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81968

--- Comment #45 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #43 from rguenther at suse dot de <rguenther at suse dot de> ---
> On Tue, 2 Jan 2018, ro at CeBiTec dot Uni-Bielefeld.DE wrote:
>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81968
>> 
>> --- Comment #42 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec
>> dot Uni-Bielefeld.DE> ---
>> > --- Comment #41 from rguenther at suse dot de <rguenther at suse dot de> ---
>> [...]
>> >> Unfortunately not: it's really the section index pointing to the
>> >> non-existing (i.e. eliminated) .gnu.debuglto_.debug_info section.
>> >
>> > But that section shouldn't be eliminated :/
>> 
>> IIUC it has been renamed to .debug_info:
>> 
>> * input object (cp_lto_pr42987_0.o):
>> 
>> Section Header[9]:  sh_name: .gnu.debuglto_.debug_info
>>     sh_addr:      0               sh_flags:   0
>>     sh_size:      0x3d4           sh_type:    [ SHT_PROGBITS ]
>>     sh_offset:    0x7fb           sh_entsize: 0
>>     sh_link:      0               sh_info:    0
>>     sh_addralign: 0x1       
>> 
>> * output object (ccw3tETddebugobjtem):
>> 
>> Section Header[2]:  sh_name: .debug_info
>>     sh_addr:      0               sh_flags:   0
>>     sh_size:      0x3d4           sh_type:    [ SHT_PROGBITS ]
>>     sh_offset:    0x84d           sh_entsize: 0
>>     sh_link:      0               sh_info:    0
>>     sh_addralign: 0x1       
>> 
>> without adapting section indices in .symtab.
>
> Yes.  It should have retained [9] as section index.  Hmmm - you
> have the patch removing sections in your tree?  I guess you need

Indeed: without it, Solaris results are far worse.

> to adapt (aka remap) the first_shndx section index I added with
> the patch for the hpux ld issue.

Right: with that change, the .symtab warnings are gone.

>> Besides, there's also a dangling
>> 
>> Section Header[6]:  sh_name: .rel.gnu.debuglto_.debug_info
>>     sh_addr:      0               sh_flags:   0
>>     sh_size:      0x8             sh_type:    [ SHT_REL ]
>>     sh_offset:    0x11c8          sh_entsize: 0x8 (1 entry)
>>     sh_link:      5               sh_info:    9
>>     sh_addralign: 0x4       
>> 
>> in the output object.
>
> that should have been used as the reloc section for the new section 2.
> I see sh_info is still 9, it should be 2.  That's eventually
> missing handling in the section removal patch.

I'll try to figure this out.

> I've committed the hpux fix so in case you re-base the patch and
> fix up the first_shndx issue please attach the rebased one.

Just did so.

        Rainer