[Bug symtab/30739] [gdb/symtab] wrong parent for cooked index entry

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=30739

--- 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=aa5b8b8cc3c0246f00617ec23ebf15203fd75242

commit aa5b8b8cc3c0246f00617ec23ebf15203fd75242
Author: Tom de Vries <tdevries@suse.de>
Date:   Thu Aug 10 21:16:30 2023 +0200

    [gdb/symtab] Fix off-by-one error in cooked_indexer::recurse

    Test-case gdb.dwarf2/pr13961.exp contains:
    ...
     <1><25>: Abbrev Number: 8 (DW_TAG_class_type)
        <26>   DW_AT_specification: <0x2a>
     <1><2a>: Abbrev Number: 2 (DW_TAG_class_type)
        <2b>   DW_AT_name        : foo
        <2f>   DW_AT_byte_size   : 4
        <30>   DW_AT_decl_file   : 1
        <31>   DW_AT_decl_line   : 1
        <32>   DW_AT_sibling     : <0x44>
    ...

    The DIE at 0x25 contains an intra-CU forward reference, and is deferred
during
    DIE indexing in the cooked_index, by adding it to m_deferred_entries.

    The resulting cooked index entries are:
    ...
            [25] ((cooked_index_entry *) 0x333b5d0)
            name:       foo
            canonical:  foo
            qualified:  foo
            DWARF tag:  DW_TAG_class_type
            flags:      0x0 []
            DIE offset: 0x2a
            parent:     ((cooked_index_entry *) 0)

            [26] ((cooked_index_entry *) 0x333b630)
            name:       foo
            canonical:  foo
            qualified:  foo::foo
            DWARF tag:  DW_TAG_class_type
            flags:      0x0 []
            DIE offset: 0x25
            parent:     ((cooked_index_entry *) 0x333b5d0) [foo]
    ...

    Notice that 0x2a is the parent of 0x25, and that this is why the qualified
    name of 0x25 is "foo::foo", which is incorrect, it's supposed to be "foo".

    The parent is set here in cooked_indexer::make_index:
    ...
      for (const auto &entry : m_deferred_entries)
        {
          void *obj = m_die_range_map.find (entry.spec_offset);
          cooked_index_entry *parent = static_cast<cooked_index_entry *> (obj);
          m_index_storage->add (entry.die_offset, entry.tag, entry.flags,
                                entry.name, parent, m_per_cu);
        }
    ...
    and AFAICT, we store in m_die_range_map the parent of the respective
    spec_offset DIE (though that's not clear from the comment describing it).

    So, the root cause of this is that when we lookup the parent for DIE 0x25,
we get
    m_die_range_map.find (0x2a) == 0x2a.

    This is an off-by-one error, fixed in cooked_indexer::recurse by:
    ...
    -      CORE_ADDR start = form_addr (parent_entry->die_offset,
    +      CORE_ADDR start = form_addr (parent_entry->die_offset + 1,
    ...
    which gives us:
    ...
        [12] ((cooked_index_entry *) 0x41e21f0)
        name:       foo
        canonical:  foo
        qualified:  foo
        DWARF tag:  DW_TAG_class_type
        flags:      0x0 []
        DIE offset: 0x25
        parent:     ((cooked_index_entry *) 0)

        [13] ((cooked_index_entry *) 0x41e2190)
        name:       foo
        canonical:  foo
        qualified:  foo
        DWARF tag:  DW_TAG_class_type
        flags:      0x0 []
        DIE offset: 0x2a
        parent:     ((cooked_index_entry *) 0)
    ...

    Tested on x86_64-linux.

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

    PR symtab/30739
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30739

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