Re: [tcf-dev] symbols.h

[Xavier Pouyollon <xavier.pouyollon@xxxxxxxxxxxxx>]

On 08/28/2014 09:16 AM, Stefan.Falk@xxxxxxxxxxxx wrote:

Hi folks!

Could someone explain to me a few things about the SYM_CLASS_* and TYPE_CLASS_* macros?

 

E.g. where do things like char, short, void struct, bit, bitfield fall into?

What would be a “cardinal class type”?

 

Thank you.

 

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Hi Stefan,

> E.g. where do things like char, short, void struct, bit, bitfield fall into?

Take a look at Dwarf3 specs, page 65.
(http://dwarfstd.org/doc/Dwarf3.pdf)

You'll got an AT_base_type with an encoding.
Depending of the encoding, you can have a boolean, an address.
 (page 146).

symbols_elf.c / get_symbol_type_class will decypher a Symbol object to return it's class.

For instance, on linux, compile a program with debug info and do readelf -wi

 <1><141>: Abbrev Number: 2 (DW_TAG_subprogram)
    <142>   DW_AT_external    : 1   
    <143>   DW_AT_name        : (indirect string, offset: 0x169): usrRtpAppInit
    <147>   DW_AT_decl_file   : 1   
    <148>   DW_AT_decl_line   : 25   
    <149>   DW_AT_prototyped  : 1   
    <14a>   DW_AT_low_pc      : 0x100044   
    <14e>   DW_AT_high_pc     : 0x100048   

That describes a function. Look in get_symbol_type_class, it will convert the TAG_subprogram as TYPE_CLASS_FUNCTION.
Same logic applies for data types like ARRAY, ENUMERATION.

> What would be a “cardinal class type”?

get_symbol_type sees :
DW_ATE_unsigned_char unsigned (character) as cardinal.

I'm not 100% sure what a cardinal type means but cardinal is number used for counting.

Hope it helps a little,
Very Best Regards,
Xavier.