Re: [PATCH] mips-tdep.c: Fix bug in evaluating signed address

Corinna Vinschen
2006-06-28T13:22:12Z

Ping?

On Jun 16 18:23, Corinna Vinschen wrote:
> If the incoming type is an *unsigned* value, then unpack_long takes the
> (un)signedness into account. This results in `val' not being signed
> extended, as the mips_integer_to_address function was originally
> designed for.

I missed to add the fact that this can be demonstrated using an existing
testcase, gdb.base/ending-run.exp with mips64-elf. There's a statement

(gdb) cle *0xa0123456

Which fails with

No breakpoint at 0xa0123456

The reason is that the breakpoint address is correctly stored sign
extended (0xffffffffa0123456), but the evaluation of "*0xa0123456"
evaluates the expression 0xa0123456 as unsigned int type. This in
turn leads to the above described behaviour.

> So, to enforce correct signedness of the resulting address, I changed
> the unpack_long call to extract_signed_integer. This way, val is always
> sign extended and the mips address is correctly signed.
>
>
> Ok to apply?
>
>
> Thanks,
> Corinna
>
>
> * mips-tdep.c (mips_integer_to_address): Call extract_signed_integer
> instead of unpack_long to maintain signedness.
>
>
> Index: gdb/mips-tdep.c
> ===================================================================
> RCS file: /cvs/cvsfiles/gnupro/gdb/mips-tdep.c,v
> retrieving revision 1.24
> diff -u -p -r1.24 mips-tdep.c
> --- gdb/mips-tdep.c 15 Jun 2006 08:57:17 -0000 1.24
> +++ gdb/mips-tdep.c 16 Jun 2006 16:15:48 -0000
> @@ -4749,7 +4749,7 @@ mips_integer_to_address (struct gdbarch
> struct type *type, const gdb_byte *buf)
> {
> gdb_byte *tmp = alloca (TYPE_LENGTH (builtin_type_void_data_ptr));
> - LONGEST val = unpack_long (type, buf);
> + LONGEST val = extract_signed_integer (buf, TYPE_LENGTH (type));
> store_signed_integer (tmp, TYPE_LENGTH (builtin_type_void_data_ptr), val);
> return extract_signed_integer (tmp,
> TYPE_LENGTH (builtin_type_void_data_ptr));