[Bug debug/93865] .debug_line with LTO refers to bogus file-names

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93865

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:ceabd8fc7c299b3428f37e8c07b0c9662b119c75

commit r10-8736-gceabd8fc7c299b3428f37e8c07b0c9662b119c75
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Sep 10 11:25:02 2020 +0200

    lto: Stream current working directory for first streamed relative filename
and adjust relative paths [PR93865]

    If the gcc -c -flto ... commands to compile some or all objects are run in
a
    different directory (or in different directories) from the directory in
    which the gcc -flto link line is invoked, then the .debug_line will be
    incorrect if there are any relative filenames, it will use those relative
    filenames while .debug_info will contain a different DW_AT_comp_dir.

    The following patch streams (at most once after each clear_line_info)
    the current working directory (what we record in DW_AT_comp_dir) when
    encountering the first relative pathname, and when reading the location
info
    reads it back and if the current working directory at that point is
    different from the saved one, adjusts relative paths by adding a relative
    prefix how to go from the current working directory to the previously saved
    path (with a fallback e.g. for DOS e:\\foo vs. d:\\bar change to use
    absolute directory).

    2020-09-10  Jakub Jelinek  <jakub@redhat.com>

            PR debug/93865
            * lto-streamer.h (struct output_block): Add emit_pwd member.
            * lto-streamer-out.c: Include toplev.h.
            (clear_line_info): Set emit_pwd.
            (lto_output_location_1): Encode the ob->current_file != xloc.file
            bit directly into the location number.  If changing file, emit
            additionally a bit whether pwd is emitted and emit it before the
            first relative pathname since clear_line_info.
            (output_function, output_constructor): Don't call clear_line_info
            here.
            * lto-streamer-in.c (struct string_pair_map): New type.
            (struct string_pair_map_hasher): New type.
            (string_pair_map_hasher::hash): New method.
            (string_pair_map_hasher::equal): New method.
            (path_name_pair_hash_table, string_pair_map_allocator): New
variables.
            (relative_path_prefix, canon_relative_path_prefix,
            canon_relative_file_name): New functions.
            (canon_file_name): Add relative_prefix argument, if non-NULL
            and string is a relative path, return canon_relative_file_name.
            (lto_location_cache::input_location_and_block): Decode file change
            bit from the location number.  If changing file, unpack bit whether
            pwd is streamed and stream in pwd.  Adjust canon_file_name caller.
            (lto_free_file_name_hash): Delete path_name_pair_hash_table
            and string_pair_map_allocator.

    (cherry picked from commit 3d0af0c997fe42a7f0963d970a9c495b81041206)