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Re: Fix PR 31903, type info for types in anonymous namespaces


On 10/30/07, Geoffrey Keating <geoffk@apple.com> wrote:
>
> On 29/10/2007, at 6:41 AM, Richard Guenther wrote:
>
> > On 10/29/07, Richard Guenther <richard.guenther@gmail.com> wrote:
> >> On 6/14/07, Geoffrey Keating <gkeating@apple.com> wrote:
> >>>
> >>> In the 'else' clause right below the code I remove, there is:
> >>>
> >>>      else if (TREE_CODE (decl) == VAR_DECL && DECL_TINFO_P (decl))
> >>>        {
> >>>          /* tinfo visibility is based on the type it's for.  */
> >>>          constrain_visibility
> >>>            (decl, type_visibility (TREE_TYPE (DECL_NAME (decl))));
> >>>        }
> >>>
> >>> which is more correct, and in the presence of the code I deleted, is
> >>> never used for type info of class types.
> >>>
> >>> Tested with 'make bootstrap', rebuilding libsdc++, and running the
> >>> C++
> >>> dejagnu testsuite on i386-apple-darwin9.
> >>
> >> This causes PR33871 and reverting the change still ends up with the
> >> testcase
> >> working.  On *-linux-gnu that is.  Any idea why?
> >>
> >> Please investigate.
> >
> > In fact, I think the new testcase should _fail_ now, but the matching
> > pattern doesn't
> > fail on
> >
> >        .file   "anon4.C"
> > .globl X
> >        .section        .rodata
> >        .align 8
> >        .type   X, @object
> >        .size   X, 8
> > X:
> >        .quad   _ZTIN12_GLOBAL__N_13fooE
> >        .section
> >         .gnu.linkonce.r._ZTSN12_GLOBAL__N_13fooE,"a",@progbits
> >        .align 16
> >        .type   _ZTSN12_GLOBAL__N_13fooE, @object
> >        .size   _ZTSN12_GLOBAL__N_13fooE, 21
> > _ZTSN12_GLOBAL__N_13fooE:
> >        .string "N12_GLOBAL__N_13fooE"
> >        .section        .rodata
> >        .align 16
> >        .type   _ZTIN12_GLOBAL__N_13fooE, @object
> >        .size   _ZTIN12_GLOBAL__N_13fooE, 16
> > _ZTIN12_GLOBAL__N_13fooE:
> >        .quad   _ZTVN10__cxxabiv117__class_type_infoE+16
> >        .quad   _ZTSN12_GLOBAL__N_13fooE
> >        .ident  "GCC: (GNU) 4.3.0 20071029 (experimental)"
> >        .section        .note.GNU-stack,"",@progbits
>
> Could you explain more about why you think it should fail?  I only see
> one instance of '.globl' in this snippet of assembler and it's not the
> one the testcase is checking for, which would look like
>
> .globl _ZTIN12_GLOBAL__N_13fooE
>
> (note that the testcase is trying to make sure that .globl does *not*
> appear.)

The symbols were weak before and are now not weak.  readelf shows
after your patch:

Symbol table '.symtab' contains 38 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
...
    14: 0000000000000000     0 SECTION LOCAL  DEFAULT   16
    15: 0000000000000020    24 OBJECT  LOCAL  DEFAULT   16
_ZTIN12_GLOBAL__N_11tE
    16: 0000000000000000     0 SECTION LOCAL  DEFAULT   18
    17: 0000000000000000    19 OBJECT  LOCAL  DEFAULT   18
_ZTSN12_GLOBAL__N_11tE

while before your patch

 26: 0000000000000000    24 OBJECT  WEAK   DEFAULT   12 _ZTIN12_GLOBAL__N_11tE
28: 0000000000000000    19 OBJECT  WEAK   DEFAULT   14 _ZTSN12_GLOBAL__N_11tE

I don't know what version is more "correct", but certainly you did change
behavior and that changed behavior broke numerous applications at
link time.  So I ask you to provide either reasoning for the change
(citing ABIs or whatever) or to restore the previous behavior to unbreak
applications.

Thanks,
Richard.


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