[fpc-devel] debug formats, differences and options?

[Graeme Geldenhuys]

Op 2010-11-08 16:34, Martin het geskryf:
> 
> In case it is in the ppu, are later dwarf downward compatible? eg, 
> compiling units with -gw3 or -gw4 => will it allow to create an exe with 
> -gw1 ?


I can't answer all your other questions, but as per the DWARF spec, 4 is
backward compatible with 3, and 3 is somewhat backward compatible with 2.


> Is there a list of the advantages, disadvantages of each format. (I 
> understand dwarf 3, and 4 are unstable, but what extra features to they 
> add (as in actually implemented features in fpc)

>From all the papers I have read I understood it as follows. DWARF 2 spec
was a mess and very vague. This caused most implementations to be
incompatible with other implementations. DWARF 3 is the first "real
standardized" spec that also tries to be future-proof - whereas it can be
extended by vendors without having to submit those extensions to become
part of the next DWARF spec. eg: you can define new types using existing
attributes etc. DWARF 4 simply builds on DWARF 3, but I haven't read in
detail what exactly is new.


As for FPC's DWARF support. The DWARF 3 class is a descendant of the DWARF
2 class. So I presume some things are reused in DWARF 3 output.... but how
correct that DWARF 3 out is, is another question.



Regards,
  - Graeme -

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