[Bug lto/96385] New: GCC generates separate debug info with undefined symbols without relocations

[Bug lto/96385] New: GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

            Bug ID: 96385
           Summary: GCC generates separate debug info with undefined
                    symbols without relocations
           Product: gcc
           Version: 10.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

Created attachment 48956
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48956&action=edit
LTO debug output

GCC may generate separate debug info files which contain undefined symbols
without relocations.  Here is the lto output from binutils LTO build:

[hjl@gnu-cfl-2 binutils-cross-run]$ readelf -rsW /tmp/gcc.lto.debug.o | grep
lreal
    96: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND lrealpath
[hjl@gnu-cfl-2 binutils-cross-run]$ 

It triggered a linker bug:

https://sourceware.org/bugzilla/show_bug.cgi?id=26314

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |lto, wrong-debug
                 CC|                            |rguenth at gcc dot gnu.org

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Such early debug is bogus - do you have the preprocessed source for the
corresponding TU?

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-07-30
             Status|UNCONFIRMED                 |WAITING
     Ever confirmed|0                           |1

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
A testcase is on pr96385 branch at:

https://gitlab.com/x86-gcc/gcc-bugs

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #3 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 30 Jul 2020, hjl.tools at gmail dot com wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385
> 
> H.J. Lu <hjl.tools at gmail dot com> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>              Status|WAITING                     |NEW
> 
> --- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
> A testcase is on pr96385 branch at:
> 
> https://gitlab.com/x86-gcc/gcc-bugs

I'd like to have the _source_ to whichever of the .o files
has the bogus relocation in the .gnulto.debug_info section.

The bug happens at the compile stage.

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 30 Jul 2020, rguenther at suse dot de wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385
> 
> --- Comment #3 from rguenther at suse dot de <rguenther at suse dot de> ---
> On Thu, 30 Jul 2020, hjl.tools at gmail dot com wrote:
> 
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385
> > 
> > H.J. Lu <hjl.tools at gmail dot com> changed:
> > 
> >            What    |Removed                     |Added
> > ----------------------------------------------------------------------------
> >              Status|WAITING                     |NEW
> > 
> > --- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
> > A testcase is on pr96385 branch at:
> > 
> > https://gitlab.com/x86-gcc/gcc-bugs
> 
> I'd like to have the _source_ to whichever of the .o files
> has the bogus relocation in the .gnulto.debug_info section.
> 
> The bug happens at the compile stage.

More specifically, .rela.gnu.debuglto_.debug_info may only contain
relocations to other .gnu.debuglto_.* sections and definitely
_not_ relocations to UNDEF symbols.

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #5 from H.J. Lu <hjl.tools at gmail dot com> ---
Please get users/hjl/pr26314/test branch at

https://gitlab.com/x86-binutils/binutils-gdb/-/tree/users/hjl/pr26314/test

and build binutils with GCC 10:

CC="/usr/gcc-10.1.1-x32/bin/gcc -flto -ffat-lto-objects -Wl,--as-needed
-fcf-protection" CXX="/usr/gcc-10.1.1-x32/bin/g++ -flto -ffat-lto-objects
-Wl,--as-needed -fcf-protection"
/export/gnu/import/git/gitlab/x86-binutils/configure \
        --enable-shared \
         \
        --enable-plugins --disable-gdb --disable-gdbserver
--disable-libdecnumber --disable-readline --disable-sim --with-sysroot=/
--with-system-zlib \
        --prefix=/usr/local \
        --with-local-prefix=/usr/local

I got

[hjl@gnu-cfl-2 build-x86_64-linux]$ nm -D binutils/.libs/ar | grep lrealpath
0000000000000000 A lrealpath
[hjl@gnu-cfl-2 build-x86_64-linux]$

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=26324

--- Comment #6 from H.J. Lu <hjl.tools at gmail dot com> ---
There is a small testcase in

https://sourceware.org/bugzilla/show_bug.cgi?id=26324

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> ---
[hjl@gnu-cfl-2 pr26324]$ cat pr15146a.c
extern int xxx;

int
bar (void)
{
  return xxx;
}

int
main ()
{ 
  return 0;
}
[hjl@gnu-cfl-2 pr26324]$ cat pr15146b.c
int xxx = 3;
[hjl@gnu-cfl-2 pr26324]$ cat pr15146c.c
[hjl@gnu-cfl-2 pr26324]$ make
gcc -B./  -O2 -g -o x -Wl,-R,. \
  -Wl,--no-copy-dt-needed-entries -Wl,--no-as-needed pr15146a.o pr15146c.so
./ld: /tmp/ccHirkTe.debug.temp.o: undefined reference to symbol 'xxx'
./ld: ./pr15146b.so: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
make: *** [Makefile:15: x] Error 1
[hjl@gnu-cfl-2 pr26324]$

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #8 from H.J. Lu <hjl.tools at gmail dot com> ---
The original pr26324a.o debug info contains reference to xxx.  But reference
to xxx has been removed by LTO.  simple_object_copy_lto_debug_sections fails
to remove the un-referenced symbol, xxx, from symbol table.

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #48956|0                           |1
        is obsolete|                            |

--- Comment #9 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 48975
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48975&action=edit
A testcase

[hjl@gnu-cfl-2 pr26324]$ make
gcc -B./ -O2 -g -flto -ffat-lto-objects   -c -o pr26324a.o pr26324a.c
gcc -B./ -O2 -g -fPIC   -c -o pr15146c.o pr15146c.c
gcc -B./ -O2 -g -fPIC   -c -o pr15146b.o pr15146b.c
gcc -B./ -shared  -o pr15146b.so pr15146b.o
gcc -B./ -shared  -o pr15146c.so pr15146c.o pr15146b.so
gcc -B./  -O2 -g -o x -Wl,-R,. \
  -Wl,--no-copy-dt-needed-entries -Wl,--no-as-needed pr26324a.o pr15146c.so
./ld: /tmp/ccCGQCqp.debug.temp.o: undefined reference to symbol 'xxx'
./ld: ./pr15146b.so: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
make: *** [Makefile:20: x] Error 1
[hjl@gnu-cfl-2 pr26324]$ 

-flto -ffat-lto-objects is the key.

[Bug lto/96385] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #10 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to H.J. Lu from comment #8)
> The original pr26324a.o debug info contains reference to xxx.  But reference
> to xxx has been removed by LTO.  simple_object_copy_lto_debug_sections fails
> to remove the un-referenced symbol, xxx, from symbol table.

The alternative is to ask linker to handle it:

https://sourceware.org/pipermail/binutils/2020-July/112673.html

[Bug lto/96385] [8/9/10/11 Regression] GCC generates separate debug info with undefined symbols without relocations

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|GCC generates separate      |[8/9/10/11 Regression] GCC
                   |debug info with undefined   |generates separate debug
                   |symbols without relocations |info with undefined symbols
                   |                            |without relocations

--- Comment #11 from H.J. Lu <hjl.tools at gmail dot com> ---
GCC 7.3.1 is OK:

[hjl@gnu-cfl-2 pr26324]$ make
/usr/gcc-7.3.1-x32/bin/gcc -B./ -O2 -g -flto -ffat-lto-objects   -c -o
pr26324a.o pr26324a.c
/usr/gcc-7.3.1-x32/bin/gcc -B./ -O2 -g -fPIC   -c -o pr15146c.o pr15146c.c
/usr/gcc-7.3.1-x32/bin/gcc -B./ -O2 -g -fPIC   -c -o pr15146b.o pr15146b.c
/usr/gcc-7.3.1-x32/bin/gcc -B./ -shared  -o pr15146b.so pr15146b.o
/usr/gcc-7.3.1-x32/bin/gcc -B./ -shared  -o pr15146c.so pr15146c.o pr15146b.so
/usr/gcc-7.3.1-x32/bin/gcc -B./  -O2 -g -o x -Wl,-R,. \
  -Wl,--no-copy-dt-needed-entries -Wl,--no-as-needed pr26324a.o pr15146c.so
./x
PASS
[hjl@gnu-cfl-2 pr26324]$

[Bug lto/96385] [8/9/10/11 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #10)
> (In reply to H.J. Lu from comment #8)
> > The original pr26324a.o debug info contains reference to xxx.  But reference
> > to xxx has been removed by LTO.  simple_object_copy_lto_debug_sections fails
> > to remove the un-referenced symbol, xxx, from symbol table.
> 
> The alternative is to ask linker to handle it:
> 
> https://sourceware.org/pipermail/binutils/2020-July/112673.html

The bug is we create the reference in the first place.

[Bug lto/96385] [8/9/10/11 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #12)
> (In reply to H.J. Lu from comment #10)
> > (In reply to H.J. Lu from comment #8)
> > > The original pr26324a.o debug info contains reference to xxx.  But reference
> > > to xxx has been removed by LTO.  simple_object_copy_lto_debug_sections fails
> > > to remove the un-referenced symbol, xxx, from symbol table.
> > 
> > The alternative is to ask linker to handle it:
> > 
> > https://sourceware.org/pipermail/binutils/2020-July/112673.html
> 
> The bug is we create the reference in the first place.

Oh, I see.  So we had multiple choices for "pruning" symbols from the symbol
table during simple_object_copy_lto_debug_sections and factoring in
HP-UX and Solaris (sic!...) emptying UND symbol names didn't work out.
So we do now

              if (discard)
                {
                  /* Make discarded symbols undefined and unnamed
                     in case it is local.  */
                  int bind = ELF_ST_BIND (*st_info);
                  int other = STV_DEFAULT;
                  if (bind == STB_LOCAL)
                    {
                      /* Make discarded local symbols unnamed and
                         defined in the first prevailing section.  */
                      ELF_SET_FIELD (type_functions, ei_class, Sym,
                                     ent, st_name, Elf_Word, 0);
                      ELF_SET_FIELD (type_functions, ei_class, Sym,
                                     ent, st_shndx, Elf_Half,
                                     sh_map[first_shndx]);
                    }
                  else
                    {
                      /* Make discarded global symbols hidden weak
                         undefined and sharing a name of a prevailing
                         symbol.  */
                      bind = STB_WEAK;
                      other = STV_HIDDEN;
                      ELF_SET_FIELD (type_functions, ei_class, Sym,
                                     ent, st_name, Elf_Word,
                                     prevailing_name_idx);
                      ELF_SET_FIELD (type_functions, ei_class, Sym,
                                     ent, st_shndx, Elf_Half, SHN_UNDEF);
                    }
                  *st_other = other;
                  *st_info = ELF_ST_INFO (bind, STT_NOTYPE);
                  ELF_SET_FIELD (type_functions, ei_class, Sym,
                                 ent, st_value, Elf_Addr, 0);
                  ELF_SET_FIELD (type_functions, ei_class, Sym,
                                 ent, st_size, Elf_Word, 0);
                }

but somehow the else path isn't triggered(?).  Note that all we try to
avoid is the need to rewrite relocation sections if we really would
prune symbols rather than NULL-ifying them somehow.  You can trace history
as to how the above code morphed with various bugs in the past...

Hmm, we don't treat SHN_UNDEF any special here - I guess we could at most
make all of them WEAK ... the following should address this.

diff --git a/libiberty/simple-object-elf.c b/libiberty/simple-object-elf.c
index c62d5bba551..7c9d492f6a4 100644
--- a/libiberty/simple-object-elf.c
+++ b/libiberty/simple-object-elf.c
@@ -1467,6 +1467,11 @@ simple_object_elf_copy_lto_debug_sections
(simple_object_read *sobj,
                       && st_shndx < shnum
                       && pfnret[st_shndx - 1] == -1)
                discard = 1;
+             /* We also need to remove global UNDEFs which can
+                cause link fails later.  */
+             else if (st_shndx == SHN_UNDEF
+                      && ELF_ST_BIND (*st_info) == STB_GLOBAL)
+               discard = 1;

              if (discard)
                {

[Bug lto/96385] [8/9/10/11 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note the symbol table entry should be "unused" (if there's anything like that).
At least ld usually treats it like so.  IIRC I left those dangling because
UNDEFs into the copied .debug_info section are bogus - and I did not want to
parse relocation sections to see where it is referenced from (otherwise I'd
assert for such UNDEFs).

I know it's all a bit awkward but originally this was supposed to be
a temporary measure until ld + plugin API understands how to only
partly claim an object and make ld link the original .gnu.debuglto_
prefixed debug-info sections unchanged into the final object ...

So you basically found a case where ld does _not_ treat the UNDEF as "unused".
In case that is not a bug in ld I am not really understanding how the bug
manifests which means I have a hard time creating a testcase for GCCs
LTO testsuite :/

Now the patch itself should be quite safe (we shouldn't be left with any
global UNDEFs).  But I'm curious if it resolves a "real" bug...

[Bug lto/96385] [8/9/10/11 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |amodra at gcc dot gnu.org

--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> ---
I also wonder if the result of the patch,

    34: 0000000000000000     0 NOTYPE  WEAK   HIDDEN     1 t.c.5958f17d
    35: 0000000000000000     0 NOTYPE  WEAK   HIDDEN   UND t.c.5958f17d
    36: 0000000000000000     0 NOTYPE  WEAK   HIDDEN   UND t.c.5958f17d
    37: 0000000000000000     0 NOTYPE  WEAK   HIDDEN   UND t.c.5958f17d

is in any way "safer" from an ELF perspective (not so much GNU ld since
we've dealt with Solaris and HP-UX linker issues in the past).

Alan, you fiddled with this earlier so any comments?

[Bug lto/96385] [8/9/10/11 Regression] GCC generates separate debug info with undefined symbols without relocations

[amodra at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #16 from Alan Modra <amodra at gmail dot com> ---
It looks fine to me, assuming you don't need to keep any of these undefined
symbols.

[Bug lto/96385] [8/9/10/11 Regression] GCC generates separate debug info with undefined symbols without relocations

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #17 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:b32c5d0b72fda2588b4e170e75a9c64e4bf266c7

commit r11-2506-gb32c5d0b72fda2588b4e170e75a9c64e4bf266c7
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Aug 3 15:05:37 2020 +0200

    lto/96385 - avoid unused global UNDEFs in debug objects

    Unused global UNDEFs can have side-effects in some circumstances so
    the following patch avoids them by treating them the same as other
    to be discarded DEFs - make them local.

    2020-08-03  Richard Biener  <rguenther@suse.de>

            PR lto/96385
    libiberty/
            * simple-object-elf.c
            (simple_object_elf_copy_lto_debug_sections): Localize global
            UNDEFs and reuse the prevailing name.

[Bug lto/96385] [8/9/10 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[8/9/10/11 Regression] GCC  |[8/9/10 Regression] GCC
                   |generates separate debug    |generates separate debug
                   |info with undefined symbols |info with undefined symbols
                   |without relocations         |without relocations
      Known to work|                            |11.0

--- Comment #18 from Richard Biener <rguenth at gcc dot gnu.org> ---
So let's see whether HPUX or Solaris folks complain.

[Bug lto/96385] [8/9/10 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |8.5

[Bug lto/96385] [8/9/10 Regression] GCC generates separate debug info with undefined symbols without relocations

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #19 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:63a2bdbfb42628800a6999e98804928855592ce7

commit r10-8746-g63a2bdbfb42628800a6999e98804928855592ce7
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Aug 3 15:05:37 2020 +0200

    lto/96385 - avoid unused global UNDEFs in debug objects

    Unused global UNDEFs can have side-effects in some circumstances so
    the following patch avoids them by treating them the same as other
    to be discarded DEFs - make them local.

    2020-08-03  Richard Biener  <rguenther@suse.de>

            PR lto/96385
    libiberty/
            * simple-object-elf.c
            (simple_object_elf_copy_lto_debug_sections): Localize global
            UNDEFs and reuse the prevailing name.

    (cherry picked from commit b32c5d0b72fda2588b4e170e75a9c64e4bf266c7)

[Bug lto/96385] [8/9 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[8/9/10 Regression] GCC     |[8/9 Regression] GCC
                   |generates separate debug    |generates separate debug
                   |info with undefined symbols |info with undefined symbols
                   |without relocations         |without relocations
      Known to fail|                            |10.2.0
           Priority|P3                          |P2
      Known to work|                            |10.2.1

[Bug lto/96385] [8/9 Regression] GCC generates separate debug info with undefined symbols without relocations

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #20 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:969be2412231d3bdd73300ac32684d416345a029

commit r9-9340-g969be2412231d3bdd73300ac32684d416345a029
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Aug 3 15:05:37 2020 +0200

    lto/96385 - avoid unused global UNDEFs in debug objects

    Unused global UNDEFs can have side-effects in some circumstances so
    the following patch avoids them by treating them the same as other
    to be discarded DEFs - make them local.

    2020-08-03  Richard Biener  <rguenther@suse.de>

            PR lto/96385
    libiberty/
            * simple-object-elf.c
            (simple_object_elf_copy_lto_debug_sections): Localize global
            UNDEFs and reuse the prevailing name.

    (cherry picked from commit b32c5d0b72fda2588b4e170e75a9c64e4bf266c7)

[Bug lto/96385] [8 Regression] GCC generates separate debug info with undefined symbols without relocations

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

--- Comment #21 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-8 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:e6a720bf5b1328ff018880063ae3d1e777e5b61d

commit r8-10922-ge6a720bf5b1328ff018880063ae3d1e777e5b61d
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Aug 3 15:05:37 2020 +0200

    lto/96385 - avoid unused global UNDEFs in debug objects

    Unused global UNDEFs can have side-effects in some circumstances so
    the following patch avoids them by treating them the same as other
    to be discarded DEFs - make them local.

    2020-08-03  Richard Biener  <rguenther@suse.de>

            PR lto/96385
    libiberty/
            * simple-object-elf.c
            (simple_object_elf_copy_lto_debug_sections): Localize global
            UNDEFs and reuse the prevailing name.

    (cherry picked from commit b32c5d0b72fda2588b4e170e75a9c64e4bf266c7)

[Bug lto/96385] [8 Regression] GCC generates separate debug info with undefined symbols without relocations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96385

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
      Known to work|                            |8.4.1
         Resolution|---                         |FIXED
      Known to fail|                            |8.4.0

--- Comment #22 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.