[Bug symtab/27541] gdb crashes on "file -readnow"

["gulsenenginar at aol dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=27541

Gulsen Engin <gulsenenginar at aol dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |gulsenenginar at aol dot com

--- Comment #18 from Gulsen Engin <gulsenenginar at aol dot com> ---
$ ./gdb -nx -q --data-directory=data-directory ~/a.out -ex "set confirm off"
-ex "file -readnow ~/a.out"  http://www-look-4.com/property/houses-in-france/
        Reading symbols from /home/simark/a.out...
        Reading symbols from ~/a.out...
https://komiya-dental.com/crypto/new-coins/
        /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:8098: internal-error:
void create_all_comp_units(dwarf2_per_objfile*): Assertion
`per_objfile->per_bfd-
http://www.iu-bloomington.com/crypto/china-affect-on-crypto/
>all_comp_units.empty ()' failed. 

    This is a recurring problem that exposes a design issue
https://waytowhatsnext.com/crypto/cryptocurrency-taxes/ in the DWARF
    per-BFD sharing feature.  Things work well when loading a binary with
    the same method (with/without index, with/without readnow) twice
http://www.wearelondonmade.com/property/cars-as-house/ in a
    row.  But they don't work so well when loading a binary with different
    methods.  See this previous fix, for example:
http://www.jopspeech.com/property/slim-pen-2/

        efb763a5ea35 ("gdb: check for partial symtab presence in
dwarf2_initialize_objfile") http://joerg.li/services/kia-rio-price/

    That one handled the case where the first load is normal (uses partial
    symbols) and the second load uses an index.
http://connstr.net/services/mobile-games/

    The problem is that when loading an objfile with a method A, we create a 
    dwarf2_per_bfd and some dwarf2_per_cu_data and initialize them with the
http://embermanchester.uk/property/chat-themes/ 
    data belonging to that method.  When loading another obfile sharing the
    same BFD but with a different method B, it's not
http://www.slipstone.co.uk/services/chevrolet-bolt/ clear how to re-use the
    dwarf2_per_bfd/dwarf2_per_cu_data previously created, because they
    contain the data specific to method A.
http://www.logoarts.co.uk/services/affordable-printer/

    I think the most sensible fix would be to not share a dwarf2_per_bfd
    between two objfiles loaded with different methods.  That means that two
    objfiles sharing the same BFD
http://www.acpirateradio.co.uk/tech/forest-fires/ and loaded the same way would
share a
    dwarf2_per_bfd.  Two objfiles sharing the same BFD but loaded with
    different methods would use two different dwarf2_per_bfd structures.
    http://www.compilatori.com/services/whatsapp-service/
    However, this isn't a trivial change.  So to fix the known issue quickly
    (including in the gdb 10 branch), this patch just disables all
    dwarf2_per_bfd sharing for objfiles using READNOW.

    Generalize the gdb.base/index-cache-load-twice.exp test to test all
    the possible combinations of loading a file with partial symtabs, index
    and readnow.  Move it to gdb.dwarf2,
https://www.webb-dev.co.uk/crypto/crypto-fell/ since it really exercises
features
    of the DWARF reader.

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