[Bug symtab/24620] [cc-with-gdb-index] SIGSEGV in write_one_signatured_type in fission-reread

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

https://sourceware.org/bugzilla/show_bug.cgi?id=24620

--- Comment #6 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=2bd3e4b8d2580839a457e221d4e1e09105248215

commit 2bd3e4b8d2580839a457e221d4e1e09105248215
Author: Tom de Vries <tdevries@suse.de>
Date:   Tue Feb 2 08:37:45 2021 +0100

    [gdb/symtab] Fix assert in write_one_signatured_type

    When running test-case gdb.dwarf2/fission-reread.exp with target board
    cc-with-gdb-index, we run into an abort during the generation of the
gdb-index
    by cc-with-tweaks.sh:
    ...
    build/gdb/testsuite/cache/gdb.sh: line 1: 27275 Aborted  (core dumped)
    ...

    This can be reproduced on the command line like this:
    ...
    $ gdb -batch ./outputs/gdb.dwarf2/fission-reread/fission-reread \
      -ex 'save gdb-index  ./outputs/gdb.dwarf2/fission-reread'
    warning: Could not find DWO TU fission-reread.dwo(0x9022f1ceac7e8b19) \
      referenced by TU at offset 0x0 [in module fission-reread]
    warning: Could not find DWO CU fission-reread.dwo(0x807060504030201) \
      referenced by CU at offset 0x561 [in module fission-reread]
    Aborted (core dumped)
    ...

    The abort is a segfault due to a using a nullptr psymtab in
    write_one_signatured_type.

    The problem is that we're trying to write index entries for the type unit
    with signature:
    ...
    (gdb) p /x entry->signature
    $2 = 0x9022f1ceac7e8b19
    ...
    which is a skeleton type unit:
    ...
    Contents of the .debug_types section:

      Compilation Unit @ offset 0x0:
       Length:        0x4a (32-bit)
       Version:       4
       Abbrev Offset: 0x165
       Pointer Size:  4
       Signature:     0x9022f1ceac7e8b19
       Type Offset:   0x0
     <0><17>: Abbrev Number: 2 (DW_TAG_type_unit)
        <18>   DW_AT_comp_dir    : /tmp/src/gdb/testsuite
        <2f>   DW_AT_GNU_dwo_name: fission-reread.dwo
        <42>   DW_AT_GNU_pubnames: 0x0
        <46>   DW_AT_GNU_pubtypes: 0x0
        <4a>   DW_AT_GNU_addr_base: 0x0
    ...
    referring to a .dwo file, but as the warnings show, the .dwo file is not
    found.

    Fix this by skipping the type unit in write_one_signatured_type if
    psymtab == nullptr.

    Tested on x86_64-linux.

    gdb/ChangeLog:

    2021-02-02  Tom de Vries  <tdevries@suse.de>

            PR symtab/24620
            * dwarf2/index-write.c (write_one_signatured_type): Skip if
            psymtab == nullptr.

    gdb/testsuite/ChangeLog:

    2021-02-02  Tom de Vries  <tdevries@suse.de>

            PR symtab/24620
            * gdb.dwarf2/fission-reread.exp: Add test-case.

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