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Re: [rfc] dwarf2 unwinder and MIPS n32
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: drow at false dot org (Daniel Jacobowitz)
- Cc: gdb-patches at sourceware dot org
- Date: Sun, 29 Apr 2007 00:40:41 +0200 (CEST)
- Subject: Re: [rfc] dwarf2 unwinder and MIPS n32
Daniel Jacobowitz wrote:
> So what do we do about it? The patch below works for MIPS, but I'm
> reasonably sure it's wrong; it avoids the architecture's
> ADDRESS_TO_POINTER method entirely. If we pass the register's type to
> store_typed_address we'll get various failures if the architecture
> doesn't define the relevant register as a pointer. And MIPS doesn't,
> partly because the register is 64-bit and the pointer would only be
> 32-bit.
Well, when we *read* a register in order to get (or compute) the CFA,
read_reg does
unpack_long (register_type (gdbarch, regnum), buf)
which in turn uses either extract_type_address, extract_signed_integer,
or extract_unsigned_integer, depending on the type.
It may make sense to perform the analogous operation when *writing*
the CFA to (an unwound copy of the contents of) a register. There
is no "pack_long", but something like
memcpy (buf, value_contents
(value_from_longest (register_type (gdbarch, regnum), cfa)),
register_size (gdbarch, regnum));
should have that effect.
Not sure if that is the right thing to do in all cases, but at least
it would be consistent ...
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com