[Bug symtab/30799] New: [gdb/symtab] hang in inherit_abstract_dies

[Bug symtab/30799] New: [gdb/symtab] hang in inherit_abstract_dies

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30799

            Bug ID: 30799
           Summary: [gdb/symtab] hang in inherit_abstract_dies
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: symtab
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

I build gdb with gcc 7.5.0 and -O2 -flto -flto-partition=one, and ran into
timeouts in gdb.gdb/*.exp.

The hang seems to be related to a self-referencing DIE:
...
 <2><91dace>: Abbrev Number: 405 (DW_TAG_label)
    <91dad0>   DW_AT_abstract_origin: <0x91dace>
...

We're stuck in this loop in inherit_abstract_dies:
...
      /* For each CHILD_DIE, find the corresponding child of                    
         ORIGIN_DIE.  If there is more than one layer of                        
         DW_AT_abstract_origin, follow them all; there shouldn't be,            
         but GCC versions at least through 4.4 generate this (GCC PR            
         40573).  */
      die_info *child_origin_die = child_die;
      dwarf2_cu *child_origin_cu = cu;
      while (true)
        {
          attr = dwarf2_attr (child_origin_die, DW_AT_abstract_origin,
                              child_origin_cu);
          if (attr == nullptr)
            break;


          child_origin_die = follow_die_ref (child_origin_die, attr,
                                             &child_origin_cu);
        }
...

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[Bug symtab/30799] [gdb/symtab] hang in inherit_abstract_dies

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30799

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
Tentative patch:
...
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index eb4cb9ba72e..d68882ae657 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -9935,8 +9935,12 @@ inherit_abstract_dies (struct die_info *die, struct
dwarf2_cu *cu)
          if (attr == nullptr)
            break;

+         die_info *prev_child_origin_die = child_origin_die;
          child_origin_die = follow_die_ref (child_origin_die, attr,
                                             &child_origin_cu);
+         if (prev_child_origin_die == child_origin_die)
+           break;
        }

       /* If missing DW_AT_abstract_origin, try the corresponding child
...

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[Bug symtab/30799] [gdb/symtab] hang in inherit_abstract_dies

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30799

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
https://sourceware.org/pipermail/gdb-patches/2023-August/201914.html

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[Bug symtab/30799] [gdb/symtab] hang in inherit_abstract_dies

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30799

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=8d83f51b91072bc3d79061eba7e564ba9be6afd7

commit 8d83f51b91072bc3d79061eba7e564ba9be6afd7
Author: Tom de Vries <tdevries@suse.de>
Date:   Mon Aug 28 16:27:58 2023 +0200

    [gdb/symtab] Handle self-reference in inherit_abstract_dies

    Building gdb with gcc 7.5.0 and -flto -O2 -flto-partition=one generates a
    self-referencing DIE:
    ...
     <2><91dace>: Abbrev Number: 405 (DW_TAG_label)
        <91dad0>   DW_AT_abstract_origin: <0x91dace>
    ...

    When encountering the self-reference DIE in inherit_abstract_dies we loop
    following the abstract origin, effectively hanging gdb.

    Fix this by handling self-referencing DIEs in the loop in
    inherit_abstract_dies.

    Tested on x86_64-linux.

    Approved-By: Tom Tromey <tom@tromey.com>

    PR symtab/30799
    https://sourceware.org/bugzilla/show_bug.cgi?id=30799

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[Bug symtab/30799] [gdb/symtab] hang in inherit_abstract_dies

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30799

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |14.1
             Status|NEW                         |RESOLVED

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
Fixed.

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