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Re: [RFA] MIPS DWARF2 CFI support
- From: Daniel Jacobowitz <drow at false dot org>
- To: "Martin M. Hunt" <hunt at redhat dot com>
- Cc: gdb-patches at sources dot redhat dot com, kevinb at redhat dot com
- Date: Tue, 8 Jun 2004 00:03:05 -0400
- Subject: Re: [RFA] MIPS DWARF2 CFI support
- References: <1086666547.5507.23.camel@hunt.cipe.redhat.com>
On Mon, Jun 07, 2004 at 08:49:08PM -0700, Martin M. Hunt wrote:
> This is really kevinb's work, with some minor tweaks. I've tested this
> on over 50 multilib combinations and it looks goood.
>
> 2004-05-26 Kevin Buettner:
>
> * dwarf2-frame.c (execute_cfa_program): Fix typo in which the
> alignment was being added to the offset instead of multiplied.
>
> * dwarf2-frame.c (struct comp_unit): Add new field ``signed_addr_p''.
> (encoding_for_size): Add new parameter ``signed_addr_p''. Adjust
> all callers. Add code for handling signed encodings.
> (dwarf2_build_frame_info): Initialize ``unit.signed_addr_p''.
>
> * dwarf2-frame.c (dwarf2_build_frame_info): Set unit.addr_size.
>
> * config/mips/tm-mips.h (SP_REGNUM): Delete define.
> * mips-tdep.h (MIPS_SP_REGNUM): Define.
> * mips-tdep.c (mips_gdbarch_init): Set SP_REGNUM via call
> to set_gdbarch_sp_regnum(). Use cooked register number.
> (SP_REGNUM): Replace all occurrences with MIPS_SP_REGNUM.
>
> * mips-tdep.c (mips_gdbarch_init): Set PC_REGNUM (via
> call to set_gdbarch_pc_regnum()) to cooked register number.
>
> * mips-tdep.c (dwarf2-frame.h): Include.
> (mips_gdbarch_init): Enable DWARF2 CFI support.
I've got three objections:
- This is a whole lot of changes. Please submit them independently,
with some sort of attempt at explanation.
> - unit.addr_size = objfile->obfd->arch_info->bits_per_address / 8;
> + unit.addr_size = TYPE_LENGTH (builtin_type_void_data_ptr);
> + unit.signed_addr_p = bfd_get_sign_extend_vma (unit.abfd);
- This is wrong; please don't introduce dependencies on GDB's type
system in dwarf2-frame.c. I imagine what's there isn't right
either because arch_info is completely unreliable on MIPS. There
is already a dwarf64_p where this is used; is that right?
Actually, this sounds like a problem in the dwarf3 draft that
someone (maybe Jim?) brought up on the dwarf2 list a few weeks ago.
Jim, do you remember?
And somewhat theoretical:
- I'd really rather not enable dwarf2 unwinding for MIPS until
someone makes a go at fixing the MIPS prologue unwinder. Either
that or rip it out; because after this patch it will get almost
zero coverage in the testsuite. This is an ongoing problem.
I know that the existing prologue unwinder is broken at the
beginning of functions and in a number of other situations.
--
Daniel Jacobowitz