[Bug cli/16224] add "pahole" functionality to ptype

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

https://sourceware.org/bugzilla/show_bug.cgi?id=16224

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Sergio Durigan Junior
<sergiodj@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7c1618381fdaa0697a211721ac31844f884797ac

commit 7c1618381fdaa0697a211721ac31844f884797ac
Author: Sergio Durigan Junior <sergiodj@redhat.com>
Date:   Mon Nov 20 16:34:59 2017 -0500

    Implement pahole-like 'ptype /o' option

    This commit implements the pahole-like '/o' option for 'ptype', which
    prints the offsets and sizes of struct fields, reporting whenever
    there is a hole found.

    The output is heavily based on pahole(1), with a few modifications
    here and there to adjust it to our reality.  Here's an example:

      /* offset    |  size */  type = struct wer : public tuv {
                           public:
      /*   32      |    24 */    struct tyu {
      /*   32:31   |     4 */        int a1 : 1;
      /*   32:28   |     4 */        int a2 : 3;
      /*   32: 5   |     4 */        int a3 : 23;
      /*   35: 3   |     1 */        char a4 : 2;
      /* XXX  3-bit hole   */
      /* XXX  4-byte hole  */
      /*   40      |     8 */        int64_t a5;
      /*   48:27   |     4 */        int a6 : 5;
      /*   48:56   |     8 */        int64_t a7 : 3;

                                 /* total size (bytes):   24 */
                             } a1;

                             /* total size (bytes):   56 */
                           }

    A big part of this patch handles the formatting logic of 'ptype',
    which is a bit messy.  The code to handle bitfield offsets, however,
    took some time to craft.  My thanks to Pedro Alves for figuring things
    out and pointing me to the right direction, as well as coming up with
    a way to inspect the layout of structs with bitfields (see testcase
    for comments).

    After many discussions both on IRC and at the mailing list, I tried to
    implement printing vtables and inherited classes.  Unfortunately the
    code grew too complex and there were still a few corner cases failing
    so I had to drop the attempt.  This should be implemented in a future
    patch.

    This patch is the start of a long-term work I'll do to flush the local
    patches we carry for Fedora GDB.  In this specific case, I'm aiming at
    upstreaming the feature implemented by the 'pahole.py' script that is
    shipped with Fedora GDB:

     
<https://src.fedoraproject.org/rpms/gdb/blob/master/f/gdb-archer.patch#_311>

    This has been regression-tested on the BuildBot.  There's a new
    testcase for it, along with an update to the documentation.  I also
    thought it was worth mentioning this feature in the NEWS file.

    gdb/ChangeLog:
    2017-12-15  Sergio Durigan Junior  <sergiodj@redhat.com>
            Pedro Alves  <palves@redhat.com>

        PR cli/16224
        * NEWS (Changes since GDB 8.0): Mention new '/o' flag.
        * c-typeprint.c (OFFSET_SPC_LEN): New define.
        (c_type_print_varspec_prefix): New argument 'struct
        print_offset_data *'.
        (c_type_print_base_1): New function and prototype.
        (c_print_type_1): New function, with code from 'c_print_type'.
        (c_print_type): Use 'c_print_type_1'.
        (c_type_print_varspec_prefix): New argument 'struct
        print_offset_data *'.  Use it.  Call 'c_type_print_base_1'
        instead of 'c_print_type_base'.
        (print_spaces_filtered_with_print_options): New function.
        (output_access_specifier): Take new argument FLAGS.  Modify
        function to call 'print_spaces_filtered_with_print_options'.
        (c_print_type_vtable_offset_marker): New function.
        (c_print_type_union_field_offset): New function.
        (c_print_type_struct_field_offset): New function.
        (c_print_type_no_offsets): New function.
        (c_type_print_base_struct_union): New argument 'struct
        print_offset_data *'.  Print offsets and sizes for
        struct/union/class fields.
        * typeprint.c (const struct type_print_options
        type_print_raw_options): Initialize 'print_offsets'.
        (static struct type_print_options default_ptype_flags):
        Likewise.
        (struct print_offset_data print_offset_default_data): New
        variable.
        (whatis_exp): Handle '/o' option.
        (_initialize_typeprint): Add '/o' flag to ptype's help.
        * typeprint.h (struct print_offset_data): New struct.
        (struct type_print_options) <print_offsets>: New field.

    gdb/testsuite/ChangeLog:
    2017-12-15  Sergio Durigan Junior  <sergiodj@redhat.com>

        PR cli/16224
        * gdb.base/ptype-offsets.cc: New file.
        * gdb.base/ptype-offsets.exp: New file.

    gdb/doc/ChangeLog:
    2017-12-15  Sergio Durigan Junior  <sergiodj@redhat.com>

        PR cli/16224
        * gdb.texinfo (ptype): Add documentation for new flag '/o'.

-- 
You are receiving this mail because:
You are on the CC list for the bug.