RE: [PATCH] DWZ aborted "write_types: Assertion `ref && ref->die_dup == NULL'"

["George, Jini Susan" <JiniSusan.George@amd.com>]

[AMD Public Use]

Hi Mark, 

This was triggering with the gdb test case gdb.dwarf2/dw4-sig-types.exp  when compiled with clang. 

Thanks,
Jini.

-----Original Message-----
From: Mark Wielaard <mark@klomp.org> 
Sent: Friday, February 5, 2021 6:39 PM
To: Sharma, Alok Kumar <AlokKumar.Sharma@amd.com>; dwz@sourceware.org
Cc: George, Jini Susan <JiniSusan.George@amd.com>; E, Nagajyothi <Nagajyothi.E@amd.com>; Achra, Nitika <Nitika.Achra@amd.com>
Subject: Re: [PATCH] DWZ aborted "write_types: Assertion `ref && ref->die_dup == NULL'"

[CAUTION: External Email]

Hi Alok,

On Fri, 2021-02-05 at 06:09 +0000, Sharma, Alok Kumar via Dwz wrote:
> Would you please review the attached patch containing modification of 
> assert condition.
> It was required to fix an abort which seem to be incorrect.
>
> There is an assert condition as "ref && ref->die_dup == NULL".
> As per definition of "struct dw_die", the structure fields starting 
> from 'die_dup' are present only if 'die_toplevel' is 1. In line with 
> this at multiple places in code, full/paritial memory is allocated for 
> pointer of type dw_die.
> Ex.  die = pool_alloc (dw_die, offsetof (struct dw_die, die_dup)); Due 
> to this, since memory is not allocated for field die_dup onwards, it 
> may contain junk values. Macro 'die_safe_dupe' must be used in place 
> of directly accessing 'die_dup' field whenever required.
>
>       * dwz.c (write_types): Use 'die_safe_dup' to access field 'die_dup'.

I think you analysis and the code fix are correct. Thanks.

This was probably missed before because -fdebug-types-section isn't the default, so we are not seeing many DWARF files with debug types.

Do you have an example where this triggers?

Thanks,

Mark