On Tue, 2005-04-19 at 18:29 +0200, Jerome Guitton wrote: > A Dwarf interpretation question: > > We have a problem to make GCC-compiled code interact with the HP > native debugger, and it looks like it is caused by the way the > attribute DW_AT_frame_base is interpreted. Apparently, when a frame > pointer can be found in a register, the value generated by GCC for the > DW_AT_frame_base of the corresponding subroutine is a register name > (i.e. DW_OP_reg<some_number>). Is it really allowed by the dwarf 2 > standard? I would tend to think that it is not. > > The "definition" of DW_AT_frame_base is: > > "A subroutine or entry point entry may also have a DW_AT_frame_base > attribute, whose value is a location description that computes the > frame base for the subroutine or entry point." > > OK. So, it is a location description. A location description can be > either a register name or an addressing operation, so at first glance > it is correct. But if the value is a "location description that > computes the frame base", when evaluated it should be an address; > so it cannot be a register name, IMHO.
> So, when a frame pointer is stored into a register <regno>, I would > say that the value of DW_AT_frame_base should be something like > "DW_OP_bregx <regno> 0" instead of something like "DW_OP_regx <regno>". We are having this exact discussion on the DWARF3 standard mailing list right now (whether fbreg has an implicit dereference, etc). You should probably take this there.
