[Bug regression/40905] New: GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[Bug regression/40905] New: GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[ramiro dot polla at gmail dot com]

GCC creates invalid executable when an array from one DLL is accessed from
another DLL in a function with __attribute__((cold)).

----------
$ cat dll1.c 
int foo[2] = {0, 1};
$ cat dll2.c
extern int foo[2];
__attribute__((cold))
int bar(void)
{
    return foo[1];
}
$ cat main.c
int bar(void);
int main()
{
    bar();
    return 0;
}
$ cat Makefile 
CC=i686-mingw32-gcc-4.4.1

all:
        $(CC) -shared -o dll1.dll dll1.c
        $(CC) -shared -o dll2.dll dll2.c dll1.dll -O2
        $(CC) -o main.exe main.c dll1.dll dll2.dll
$ make
i686-mingw32-gcc-4.4.1 -shared -o dll1.dll dll1.c
i686-mingw32-gcc-4.4.1 -shared -o dll2.dll dll2.c dll1.dll -O2
Info: resolving _foo by linking to __imp__foo (auto-import)
/opt/i686-mingw32/lib/gcc/i686-mingw32/4.4.1/../../../../i686-mingw32/bin/ld:
warning: auto-importing has been activated without --enable-auto-import
specified on the command line.
This should work unless it involves constant data structures referencing
symbols from auto-imported DLLs.
i686-mingw32-gcc-4.4.1 -o main.exe main.c dll1.dll dll2.dll
$ ./main.exe
err:module:attach_process_dlls "dll2.dll" failed to initialize, aborting
err:module:LdrInitializeThunk Main exe initialization for
L"Z:\\home\\ramiro\\code\\smalls\\gcc_bug\\main.exe" failed, status c0000005
----------
This error message is from wine, but it also fails on Windows XP.

The auto-import warning seems to fit perfectly here but the same test doesn't
fail at -O1, or if __attribute__((cold)) is removed.


-- 
           Summary: GCC creates invalid executable with auto-imported DLL
                    and __attribute__((cold))
           Product: gcc
           Version: 4.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ramiro dot polla at gmail dot com
GCC target triplet: i686-mingw32


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2009-07-29 16:10 -------
IIRC the cold attribute does a couple of things.  The only thing I think that
might cause this is putting it into a .text.cold section.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|regression                  |target


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[ramiro dot polla at gmail dot com]

------- Comment #2 from ramiro dot polla at gmail dot com  2009-07-30 03:43 -------
I might be guessing wildly since I don't know that much about PE, but this is
what more I've found:

It crashes loading the dll in __pei386_runtime_relocator at address 65ec12a8:
65ec1290 <__pei386_runtime_relocator>:
65ec1290:       55                      push   %ebp
65ec1291:       b9 28 40 ec 65          mov    $0x65ec4028,%ecx
65ec1296:       89 e5                   mov    %esp,%ebp
65ec1298:       eb 14                   jmp    65ec12ae
<__pei386_runtime_relocator+0x1e>
65ec129a:       8d b6 00 00 00 00       lea    0x0(%esi),%esi
65ec12a0:       8b 51 04                mov    0x4(%ecx),%edx
65ec12a3:       8b 01                   mov    (%ecx),%eax
65ec12a5:       83 c1 08                add    $0x8,%ecx
65ec12a8:       01 82 00 00 ec 65       add    %eax,0x65ec0000(%edx)
65ec12ae:       81 f9 30 40 ec 65       cmp    $0x65ec4030,%ecx
65ec12b4:       72 ea                   jb     65ec12a0
<__pei386_runtime_relocator+0x10>
65ec12b6:       5d                      pop    %ebp
65ec12b7:       c3                      ret    


In the same testcase compiled without -O2, I get the sole entry of
runtime_pseudo_reloc in __RUNTIME_PSEUDO_RELOC_LIST__ (the equivalent to
0x65ec4028) is:

addend = 0x00000004
target = 0x000011d5

and the .text section is:
  0 .text         00000344  67701000  67701000  00000400  2**4
                  CONTENTS, ALLOC, LOAD, CODE, DATA

With -O2 it is:
addend = 0x00000004
target = 0x00002005

  0 .text         00000334  65ec1000  65ec1000  00000600  2**4
                  CONTENTS, ALLOC, LOAD, CODE, DATA
  1 .text.unlikely 0000000c  65ec2000  65ec2000  00000a00  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE

Is it possible that it triggers the exception trying to write in text.unlikely
which is READONLY?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2009-07-30 03:59 -------
Doesn't DLL source need to be compiled with -fPIC to allow it to work?

So what is happening is you are getting a runtime relocation inside the
.text.unlikely section which should not happen for DLLs I think ...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[dannysmith at users dot sourceforge dot net]

------- Comment #4 from dannysmith at users dot sourceforge dot net  2009-07-30 08:00 -------
(In reply to comment #2)

> 
> Is it possible that it triggers the exception trying to write in text.unlikely
> which is READONLY?
> 

Exactly.  This is a linker, not a compiler issue.  If you are using a
relatively recent binutils and mingw run time, the addition of the switch
-Wl,--enable-runtime-pseudo-reloc-v2 should get around the READONLY problem.
Otherwise, you could always just add __declspec (dllimport) to
 extern int foo[2]; and so retain portability with the rest of the PE-COFF
world.

Danny


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[ktietz at gcc dot gnu dot org]

------- Comment #5 from ktietz at gcc dot gnu dot org  2009-09-04 13:27 -------
(In reply to comment #4)
> (In reply to comment #2)
> 
> > 
> > Is it possible that it triggers the exception trying to write in text.unlikely
> > which is READONLY?
> > 
> 
> Exactly.  This is a linker, not a compiler issue.  If you are using a
> relatively recent binutils and mingw run time, the addition of the switch
> -Wl,--enable-runtime-pseudo-reloc-v2 should get around the READONLY problem.
> Otherwise, you could always just add __declspec (dllimport) to
>  extern int foo[2]; and so retain portability with the rest of the PE-COFF
> world.
> 
> Danny
> 

Right, this is a linker issue (or runtime issue of pseudo-relocation). But
newer mingw32's runtime uses new code for v1 relocations, too. So for it, this
issue should be solved, too.

So can we close this bug?

Cheers,
Kai


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[ktietz at gcc dot gnu dot org]

------- Comment #6 from ktietz at gcc dot gnu dot org  2009-09-12 10:55 -------
I added you to this thread, as you merged new pseudo-relocation code to
mingw.org's runtime.


-- 

ktietz at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dannysmith at users dot
                   |                            |sourceforge dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[ktietz at gcc dot gnu dot org]

------- Comment #7 from ktietz at gcc dot gnu dot org  2010-04-05 09:17 -------
(In reply to comment #6)
> I added you to this thread, as you merged new pseudo-relocation code to
> mingw.org's runtime.
> 

As cygwin and mingw.org are supporting now new linker generated
runtime-pseudo-relocation, could you please confirm that your issue is solved.
I tested your issue and for me it works with recent version of cygwin/mingw.org
runtimes.

Kai


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905

[Bug target/40905] GCC creates invalid executable with auto-imported DLL and __attribute__((cold))

[ktietz at gcc dot gnu dot org]

------- Comment #8 from ktietz at gcc dot gnu dot org  2010-05-23 07:41 -------
As there is no feed-back for some time now. I've tested this issue with recent
mingw runtimes and the issue is solved.
As this isse is related to old pseudo-relocation and linker, and not related to
gcc itself, I close this bug as works-for-me.


-- 

ktietz at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |WORKSFORME


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40905