Another AIX Bootstrap failure

[David Edelsohn]

It looks like _Settings is miscompiled, or more specifically a
function descriptor has a bogus value

   0x100bcbac <_ZN14__gnu_parallel9_SettingsC1Ev>:      addi    r12,r2,-168
   0x100bcbb0 <_ZN14__gnu_parallel9_SettingsC1Ev+4>:    stw     r2,20(r1)
   0x100bcbb4 <_ZN14__gnu_parallel9_SettingsC1Ev+8>:    lwz     r0,0(r12)
   0x100bcbb8 <_ZN14__gnu_parallel9_SettingsC1Ev+12>:   lwz     r2,4(r12)
   0x100bcbbc <_ZN14__gnu_parallel9_SettingsC1Ev+16>:   mtctr   r0
=> 0x100bcbc0 <_ZN14__gnu_parallel9_SettingsC1Ev+20>:   bctr

(gdb) x/x $r2-168
0x3002f90c <__dbargs+11440>:    0x100bcbac
(gdb) x/x $r12
0x3002f90c <__dbargs+11440>:    0x100bcbac
(gdb) p/x $ctr
$5 = 0x100bcbac

For some reason, the additional inlining is creating the wrong address
for the target.

- David



On Mon, Jun 16, 2014 at 6:06 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> On Mon, Jun 16, 2014 at 12:35 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>>
>> > @@ -512,9 +516,9 @@ function_and_variable_visibility (bool w
>> >                      next = next->same_comdat_group)
>> >                 {
>> >                   next->set_comdat_group (NULL);
>> > -                 if (!next->alias)
>> > -                   next->set_section (NULL);
>> >                   symtab_make_decl_local (next->decl);
>> > +                 if (!node->alias)
>> > +                   node->reset_section ();
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> >                   next->unique_name = ((next->resolution == LDPR_PREVAILING_DEF_IRONLY
>> >                                         || next->unique_name
>> >                                         || next->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
>>
>> Honza, did you really intend to change the above from next->alias and
>> next->set_section () to node->alias and node->reset_section () ?  That
>> doesn't look right.
>
> You are right, this is a pasto in anoying code duplication here.  I fixed that
> in my local copy of the patch.  I have a followup patch in the ipa-visibility
> TLC to merge the code duplication here, I am just holding it until we debug the
> issues.
>
> This bug will not affect AIX, becuase there are no comdat groups.  It only
> wastes a bit of code size on ELF systems because of extra alignment coming
> from the named section.
>
> The hang happens in
> (gdb) bt
> #0  0x100be244 in __gnu_parallel::_Settings::_Settings() ()
> #1  0x10008d54 in _GLOBAL__FI_libstdc___so ()
> #2  0x10008e88 in _GLOBAL__AIXI_libstdc___so ()
> #3  0x100be954 in _GLOBAL__FI_genconstants ()
> #4  0xd017fa54 in mod_init1 () from /usr/lib/libc.a(shr.o)
> #5  0xd017f774 in __modinit () from /usr/lib/libc.a(shr.o)
> #6  0x100001a0 in __start ()
>
> I suppose it may be crtbegin/crtend miscompile.  Any insight would be welcome,
> otherwise I will try to progress on debugging tonight or tomorrow.
>
> Honza