[Dwarf-Discuss] DW_OP_regX vs. DW_OP_bregX 0

David Anderson davea42 at earthlink.net
Thu Feb 12 14:47:03 PST 2009


Roland McGrath wrote:
>> GCC is producing nonstandard expressions.
>>     
>
> That is not in dispute.
>
>   
>> If the 0 offset happens really a lot, it could be worth doing something
>> about it.  Blessing GCC's current behavior doesn't feel right, though,
>> as it overloads DW_OP_regN to mean one thing when used by itself and 
>> another thing when embedded in a larger expression.  
>>     
>
> One could say that DW_OP_addr is overloaded in the same way.
> Alone it means "this address is the location".  Embedded it
> means "push this address on the expression stack".  The two
> (proposed) meanings for DW_OP_reg* are precisely analogous.
>
>   
Roland, I suppose  you mean  "gcc overloads DW_OP_addr
in a similar non-standard way". ?  What else could you mean?

DW_OP_addr is not overloaded in the DWARF3 spec.  Either alone or
any other way it means 'push this address on the expression stack'.
Nothing else.

At least ... AFAICT.
DavidAnderson






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