Re: [RFA/RFC] dwarf2-frame read_reg

[Michael Snyder <msnyder@redhat.com>]

Mark Kettenis wrote:
>>Date: Tue, 11 Apr 2006 21:42:01 -0700
>>From: "Jim Blandy" <jimb@red-bean.com>
>>
>>On 4/11/06, Michael Snyder <msnyder@redhat.com> wrote:
>>
>>>I want you guys to vett this change.  I was getting wrong results
>>>on a target where sizeof (SP) != sizeof (void *).  The local func
>>>read_reg was calling extract_unsigned_integer with the wrong size.
>>
>>Well, extract_typed_address requires the type of the register to be
>>some sort of pointer.  read_reg is given as a callback to the Dwarf
>>expression evaluator in dwarf2expr.c, so it could be handed any
>>register at all.
>>
>>How about unpack_long (buf, register_type (gdbarch, regnum))? 
>>Definitely regression-test this on several platforms...
> 
> 
> This is likely to be wrong for platforms where addresses are signed.
> 
> Michael, what kind of funny target is this?  It has a stack pointer
> register, but its size is different from the size of pointers?

Yep, the reg size is 3 bytes.  When it's pushed onto the stack,
it occupies 3 bytes of memory.  Funky, huh?  The cpu can only
reach 24 bits worth of address space.