DWARF-2 and address sizes

[Daniel Jacobowitz <drow@mvista.com>]

[Kevin, I noticed you doing some work in this area re S/390, maybe you've
got a comment?  Anyone else?  I'm grasping at straws.]

I'm trying to figure out how to handle addresses in the DWARF expression
evaluator.  First consider DW_OP_deref: the following data is "the size of
an address on the target machine", which I would personally take to mean
cu_header->addr_size.  Is this ever different from TARGET_ADDRESS_BIT /
TARGET_CHAR_BIT, which is what Daniel was originally using?  Do we have to
worry about a binary in which different compilation units (or different
shared objects, even) have a different value for this?

If the consensus is "no, that's too stupid to be allowed to live", then this
gets much easier.

(Then consider DW_OP_deref_size; this is a fun one, since it has to be
zero-extended to the size of an address on the target machine according to
the spec, and then in GDB it may have to be zero or sign extended to the
size of a CORE_ADDR for storage.  I haven't tested any of this on MIPS yet
and I don't want to, damn it.  I don't know of any MIPS ABI with multiple
pointer sizes, and you can't link different ABIs, so encountering
DW_OP_deref_size is probably impossible.  I hope.)

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer