Re: MPS: unable to build due to assertion violation in igc_dump_check_object_starts

["Gerd Möllmann" <gerd.moellmann@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Tue, 23 Jul 2024 17:26:29 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: pipcet@protonmail.com, eller.helmut@gmail.com, emacs-devel@gnu.org
>> 
>>   #3  0x00fee189 in igc_dump_check_object_starts (relocs=0x11d32853,
>>       dump_base=0x1aa41020, hot_start=0x1aa41098, hot_end=0x1b055c70,
>>       cold_start=0x1b081020, heap_end=0x1b1f9e98) at igc.c:4820
>>   4820              eassert (end == p);
>>   (gdb) p obj_size(start)
>>   $1 = 801749580
>>   (gdb) p igc_header_nwords(start)
>>   $2 = 200437395
>>   (gdb) p header_tag(start)
>>   $3 = 0
>>   (gdb) p header_nwords(start)
>>   $4 = 200437395
>>   (gdb) p *(struct igc_header *)start
>>   $5 = {v = 1721744118644157000}
>>   (gdb) p/x *(struct igc_header *)start
>>   $6 = {v = 0x17e4dd2759e72a48}
>
> And note that the next region after the one that causes the abort
> seems to be perfectly normal:
>
>   #3  0x00fee189 in igc_dump_check_object_starts (relocs=0x11ce31a3,
>       dump_base=0x1a9d5020, hot_start=0x1a9d5098, hot_end=0x1afe41e8,
>       cold_start=0x1b005020, heap_end=0x1b17de88) at igc.c:4820
>   4820              eassert (end == p);
>   (gdb) ptype struct igc_header
>   type = struct igc_header {
>       uint64_t v;
>   }
>   (gdb) p obj_size(end)
>   $1 = 24
>   (gdb) p header_tag(end)
>   $2 = 1
>   (gdb) p IGC_TAG_EXTHDR+0
>   $4 = 2
>   (gdb) p *(struct igc_header *)end
>   $5 = {v = 55835531293}
>   (gdb) p/x *(struct igc_header *)end
>   $6 = {v = 0xd000e981d}
>   (gdb)
>
> So some relocation in the pdump corresponds to a corrupted bloc or
> something?

Could you do

  p header_type(start)

please, that should show the IGC_OBJ_xy type of the offending header

  p header_nwords(start)

is the, presumably wrong, size in words, but I think we have already
seen it's too large.