[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 #38 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
>> --- Comment #33 from rguenther at suse dot de <rguenther at suse dot de> ---
> [...]
>>>* Invalid sh_info:
>>>
>>>FAIL: g++.dg/lto/pr42987 cp_lto_pr42987_0.o-cp_lto_pr42987_1.o link, 
>>>-flto
>>>-flto-partition=none -g 
>>>FAIL: g++.dg/lto/pr42987 cp_lto_pr42987_0.o-cp_lto_pr42987_1.o link, 
>>>-flto -g 
>>>
>>>ld: fatal: file /var/tmp//ccXwdzGddebugobjtem: section
>>>[6].rel.gnu.debuglto_.debug_info: has invalid sh_info: 9
>>>ld: fatal: file /var/tmp//ccuVJOVbdebugobjtem: section
>>>[6].rel.gnu.debuglto_.debug_info: has invalid sh_info: 8
>>>
>>>  seen during the ld -r -o ccrIZb_ddebugobj ccSerOuddebugobjtem
>>>  cc5b3Arcdebugobjtem step:
>>>
>>>ccSerOuddebugobjtem: .rel.gnu.debuglto_.debug_info: sh_info: 9: does
>>>not point
>>>to a valid section
>>>
>>>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       
>>>
>>>  But there's no section 9 any longer.
>>
>> I fixed that in the posted patch for the hpux issue(s). 
>
> Good: I'll try to merge the two after the christmas holidays.

I've used the attached patch, with mixed results:

* No changes on SPARC (which wasn't affected by this issue in the first
  place).

* On x86, of the previous 32 ld: fatal: has invalid sh_info errors, 16
  are now gone.

  However, I've many (1284 in g++.log) instances of

ld: warning: symbol .symtab[2] has invalid section index; ignored:
        (file /var/tmp//ccyttLYbdebugobjtem value=9);

  Those links end with

ld: fatal: file /var/tmp//ccyttLYbdebugobjtem: section
[6].rel.gnu.debuglto_.debug_info: has invalid sh_info: 9

  and ld SEGVing, again in the ld -r step.

  The warnings are from symtab entries like

Symbol Table Section:  .symtab
  index  value size  type bind oth ver shndx         name
    [0]      0    0  NOTY LOCL  D    0 UNDEF         
    [1]      0    0  FILE LOCL  D    0 ABS           pr42987_0.C
    [2]      0    0  NOTY LOCL  D    0 9             

  and section 9 doesn't exist, where the input object (cp_lto_pr42987_0.o) has

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       

Symbol Table Section:  .symtab
  index  value size  type bind oth ver shndx / name
    [0]      0    0  NOTY LOCL  D    0 UNDEF          
    [1]      0    0  FILE LOCL  D    0 ABS            pr42987_0.C
    [2]      0    0  SECT LOCL  D    0 .text          
    [3]      0    0  SECT LOCL  D    0 .gnu.debuglto_.debug_info 

        Rainer