Re: [RFC/RFA] MIPS extract_return_value

[Andrew Cagney <cagney@gnu.org>]

> Hey Andrew, Daniel,
> 
> I encountered another problem with 32/64 bit mips.  Don't know if this
> is the right way to fix it, but it illustrates it (and fixes several
> hundred failures).
> 
> The problem is that extract_return_value and store_return_value both
> call return_value_location, but then one of them uses the raw register
> and the other uses the cooked register (which are not the same size).
> So the offset into the register cache, computed by
> return_value_location, has to be wrong for one of them.

The underlying problem here is that eabi (32 and 64) and o64 still use:

       set_gdbarch_deprecated_store_return_value (gdbarch,
       set_gdbarch_deprecated_extract_return_value (gdbarch,

There should instead be separate eabi and o64 return_value methods (see 
  mips_n32n64_return_value for an example).

If this is done the return/finish code will really be fixed (and as a 
side effect return_value_location will be eliminated).  Can that be done?

> The simple-minded approach I've taken below is to add a parameter
> to return_value_location, telling it whether to use the raw or cooked
> registers.  I've only tested it on one architecture (isa64 with gcc
> -mips32), so consider it more of a suggestion than a patch.

Just FYI, the code should just manipulate the cooked registers.

Andrew