[RFC] Use address_from_register in dwarf2-frame.c:read_addr_from_reg
Maciej W. Rozycki
macro@codesourcery.com
Wed Aug 27 18:15:00 GMT 2014
On Wed, 27 Aug 2014, Ulrich Weigand wrote:
> Andrew Pinski wrote:
>
> > I think this patch broke MIPS64 n32 big-endian support. We assert here:
> > gdb_assert (!gdbarch_convert_register_p (gdbarch, regnum, type));
> >
> > The convert_register_p code for MIPS does:
> > return (register_size (gdbarch, regnum) == 8
> > && regnum % num_regs > 0 && regnum % num_regs < 32
> > && TYPE_LENGTH (type) < 8);
> >
> >
> > Since the register size is 8 byte wide (MIPS64) and the type length is
> > 4 (pointer), we return true. In MIPS64, the registers are stored
> > 64bits but pointers are 32bits.
> >
> > Here is the code that is used by mips_register_to_value:
> > int len = TYPE_LENGTH (type);
> > CORE_ADDR offset;
> >
> > offset = gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG ? 8 - len : 0;
> > if (!get_frame_register_bytes (frame, regnum, offset, len, to,
> > optimizedp, unavailablep))
> > return 0;
> >
> > *optimizedp = *unavailablep = 0;
> > return 1;
>
> Huh, I wasn't aware of that conversion. Note that for the register_to_value
> case, I don't actually see any difference to the default behavior; it's the
> value_to_register routine that's really special (because of the sign-extension
> in performs).
>
> > Is there a way to fix this in a target neutral way? (I might need a
> > way like this for AARCH64 ILP32 also).
>
> I guess it isn't too hard to support gdbarch_convert_register_p in that
> routine as well; I just didn't have any target to test on.
>
> Can you try whether something along the following lines works for you?
I'll see if I can push it through testing, though it may take a few days
as some of MIPS hardware I use (and especially 64-bit one) is slooow (and
I already have a test run under way).
I'd expect the issue to be consistent across all ILP32 64-bit ABIs BTW,
that is e.g. x32 x86-64 as well.
Maciej
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