[rfc] For mips, sign-extended ecoff offsets

[Ulf Carlsson]

Hi Andrew,

 > > > The attatched patch changes the MIPS ELF32 backend so that it is more
 > > > likely to return a sign-extended offset.  At present the ELF backend
 > > > returns sign-extended symbol table values but not sign extended debug
 > > > information.
 > > 
 > > Hi Andrew,
 > >    Would it be better to just change ecoff_swap_sym_in?  It seems like
 > > this would achieve what you want, and not risk breaking quite so much.
 > > I'm worried about what happens if things like PDR.adr get changed from
 > > 0xa0000000 to 0xffffffffa0000000.
 > 
 > Thats why I'm asking :-) Remember though, on the MIPS platform, if
 > ``PDR.adr'' is an address then, the canonical form of the value
 > ``0xa0000000'' obtained from an elf32 binary is 0xffffffffa00000000. 
 > GDB and BFD have, for too many years, been bribed and cajoled into
 > perpetuated the lie that MIPS doesn't sign extend addresses.   GDB's now
 > decided to come clean on this matter (and purge an amazing amount of
 > bogus code :-).

On a 64-bit MIPS processor 32-bit addresses are of course sign
extended, but this shouldn't concern the 32-bit BFD backend for MIPS
in any way.  Whether we sign extend the addresses or not shouldn't
make any difference except in our internal representation of the
bfd_vma.  I may be wrong though!

Ulf