[fpc-pascal] Obtain Class hierarchy (in MacPas mode)

Adriaan van Os fpc at microbizz.nl
Mon Sep 27 14:51:19 CEST 2010

Michael Van Canneyt wrote:
> On Tue, 21 Sep 2010, Adriaan van Os wrote:
>> Michael Van Canneyt wrote:
>>> On Tue, 21 Sep 2010, Florian Klaempfl wrote:
>>>> Am 21.09.2010 13:42, schrieb Adriaan van Os:
>>>>> Michael Van Canneyt wrote:
>>>>>> On Tue, 21 Sep 2010, Adriaan van Os wrote:
>>>>>>> I am looking for a way to obtain the class hierarchy of a program in
>>>>>>> MacPas mode (where there are no published properties). TObject has
>>>>>>> ClassParent, so a list of Class types would be sufficient, I 
>>>>>>> think. I
>>>>>>> can't find however a routine in the RTL to obtain such a list.
>>>>>> There is no such routine in the RTL, to my knowledge.
>>>>> Can I add it ? I guess a low-level pointer to a list of VMT's would be
>>>>> sufficient to implement it ?
>>>> Problem is: it breaks smartlinking.
>> Yes, I understand that. I looked at the assembly generated for a 
>> simple test program and there are separate al_globals entries for each 
>> vmt and separate al_rtti entries for the vmt rtti. I asssume the very 
>> reason for the separate entries is smart linking.
>> Hm, I guess I can look at the data section of the executable but it 
>> would be highly dependant of the executable binary format.
>> Is it possible to produce a separate data section/entry that refers to 
>> all al_globals and/or all al_rtti entries without breaking 
>> smart-linking ?
> Maybe when doing whole-program optimization as implemented by Jonas.
> I guess the WPO could be extended to generate the tree you want.
> But under 'normal' compilation, I don't think it is possible to do as you
> ask without breaking the smartlinking stuff; the tree would of necessity
> contain all declared classes of all loaded units.

I implemented it now by looking at the Mach-O symbol table. It works like a charm (only classes 
that are actually used are listed and it doesn't break smart-linking).

If someone feels like implementing this for other binary formats (with the purpose of adding it to 
the rtl), I can donate the Mach-O source code under the usual license.


Adriaan van Os

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