[Bug lto/51859] New: wrapped symbols (wrap linker option) do not link

[Bug lto/51859] New: wrapped symbols (wrap linker option) do not link

[ncahill_alt at yahoo dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51859

             Bug #: 51859
           Summary: wrapped symbols (wrap linker option) do not link
    Classification: Unclassified
           Product: gcc
           Version: 4.6.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ncahill_alt@yahoo.com


The following command,
> gcc -flto -Wl,-wrap,malloc -o a a.c
produces the following error,

`__wrap_malloc' referenced in section `.text' of
/tmp/ccCKjgAw.ltrans0.ltrans.o: defined in discarded section `.text' of
/tmp/ccREUpxM.o (symbol from plugin)
collect2: ld returned 1 exit status

Here is the test case:

--- a.c ---
void * __wrap_malloc(int bytes)
{
 __real_malloc(bytes);
}

int main()
{
 int *p = (int *)malloc(4);
 *p = 2;
 free(p);
 return 0;
}
--- end a.c ---

This has the result that xorg-server 1.11.2 does not build with lto enabled.
Thank you.

Neil.

[Bug lto/51859] Linker option effects not reflected in symbol resolution file

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51859

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-01-16
                 CC|                            |davek at gcc dot gnu.org
            Summary|wrapped symbols (wrap       |Linker option effects not
                   |linker option) do not link  |reflected in symbol
                   |                            |resolution file
     Ever Confirmed|0                           |1
           Severity|normal                      |enhancement

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-16 10:58:24 UTC ---
The linker plugin tells us:

1
t.o 3
164 4a7bed50da22d738 PREVAILING_DEF_IRONLY __wrap_malloc
172 4a7bed50da22d738 PREVAILING_DEF main
176 4a7bed50da22d738 RESOLVED_DYN __real_malloc

but it doesn't communicate in any way that malloc should refer to
__wrap_malloc.
That would be a nice enhancement.

For now you need to mark the __wrap_malloc function with __attribute__((used))
because we do not see any reference to it and thus remove it as dead during
optimization.

[Bug lto/51859] Linker option effects not reflected in symbol resolution file

[d.g.gorbachev at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51859

--- Comment #2 from Dmitry Gorbachev <d.g.gorbachev at gmail dot com> 2012-01-16 17:39:13 UTC ---
Created attachment 26343
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26343
Testcase

I also experienced this bug.

`_Unwind_Resume' referenced in section `.text' of
/tmp/ccsXTIlG.ltrans0.ltrans.o: defined in discarded section `.text' of foo.o
(symbol from plugin)

1
foo.o 7
160 fb8ca3051c18d571 PREVAILING_DEF_IRONLY _Unwind_Resume
167 fb8ca3051c18d571 PREVAILING_DEF foo
171 fb8ca3051c18d571 RESOLVED_EXEC __gxx_personality_v0
178 fb8ca3051c18d571 RESOLVED_EXEC __cxa_rethrow
180 fb8ca3051c18d571 RESOLVED_EXEC __cxa_begin_catch
186 fb8ca3051c18d571 RESOLVED_EXEC __cxa_end_catch
188 fb8ca3051c18d571 RESOLVED_EXEC bar

[Bug lto/51859] Linker option effects not reflected in symbol resolution file

[d.g.gorbachev at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51859

--- Comment #3 from Dmitry Gorbachev <d.g.gorbachev at gmail dot com> 2012-01-16 17:40:24 UTC ---
Created attachment 26344
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26344
Testcase #2 (mingw32 target)

`_bar' referenced in section `.text' of libfoobar.a(foo.o): defined in
discarded section `.text' of bar.o (symbol from plugin)

2
main.o 2
160 319f6338eecb5274 PREVAILING_DEF_IRONLY_EXP _main
164 319f6338eecb5274 RESOLVED_IR _bar
libfoobar.a@0xcc6 1
160 d8dca87d54fff4c6 PREVAILING_DEF_IRONLY _bar

[Bug lto/51859] Linker option effects not reflected in symbol resolution file

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51859

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-18 10:08:39 UTC ---
*** Bug 51887 has been marked as a duplicate of this bug. ***