[Dwarf-Discuss] How to interpret DW_AT_artificial tag?

[Ron Louzon]

 Thanks for the responses.? We have mission critical airborne real-time processors and we have tools which use the DWARF information to locate and monitor variables while the processors are running.? Our tools generate memory addresses of the variables to be monitored and when addressing certain structures, these DW_AT_artifical members will cause the actual structure members to move in memory.? Your responses have verified what I thought I was seeing in the DWARF information.? Thanks again.? - ron??

    On Monday, February 28, 2022, 09:01:39 AM EST, Robinson, Paul <paul.robinson at sony.com> wrote:  
 
 
DW_AT_artificial generally means the item is compiler-generated, or otherwise has no explicit representation in the source.
 
An artificial member in a structure takes up however much space it takes, just like any other member, and the compiler should have generated the correct offsets for the other members of the structure.? So, I?d expect the first non-artificial member to have offset 4 (or greater).? Whether the consumer (in this case, your application) has to compensate really depends on what the application is doing.
 
--paulr
 
 ?
 
From: Dwarf-Discuss <dwarf-discuss-bounces@lists.dwarfstd.org>On Behalf Of Ron Louzon via Dwarf-Discuss
Sent: Monday, February 28, 2022 8:50 AM
To: Dwarf-Discuss at lists.dwarfstd.org
Subject: [Dwarf-Discuss] How to interpret DW_AT_artificial tag?
 
 ?
 
I have an application which uses DwarfLib to extract type information from debug executable images.? I have found in the DWARF data that some structure types have a "virtual" pointer added as their first member and this pointer's DIE contains the tag DW_AT_artificial=true.? How does that pointer member affect the offsets of the members that follow it in the structure.? Should this 4-byte pointer be ignored or will its size cause the other structure members to be pushed out in memory by 4 bytes?
 
 ?
 
thanks,
 
ron
   
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