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Re: [RFA] mips 32/64 register/stack fix
On Thu, Apr 29, 2004 at 09:40:23AM -0400, Andrew Cagney wrote:
> >On Wed, Apr 28, 2004 at 05:45:22PM -0400, Andrew Cagney wrote:
> >
> >>>>>Here's your tdep info:
> >>>>>{elf_flags = 1610625025, mips_abi = MIPS_ABI_EABI32,
> >>
> >>>
> >>>I was looking to see if anything like that was present -> it is clearly
> >>>identified as a 32-bit ABI binary.
> >>>
> >>>I think the bug is in mips_register_type, the tail end should probably
> >>>be changed to read something like:
> >>>
> >>> else if (regnum >= NUM_REGS
> >>> && gdbarch_tdep (gdbarch)->mips64_transfers_32bit_regs_p)
> >>> /* The target, while using a 64-bit raw register buffer, is only
> >>> transfering 32-bits of each integer register. Reflect this in
> >>> the cooked/pseudo register value. */
> >>> return builtin_type_int32;
> >>> else if (regnum > NUM_REGS
>
> >= NUM_REGS
>
> >>> && mips_saved_regsize (gdbarch) == 4)
> >>> /* A 32-bit ABI such as o32 possibly running on a 64-bit ISA. */
> >>> return builtin_type_int32;
> >>> else if (mips_regsize (gdbarch) == 8)
> >>> /* 64-bit ISA. */
> >>> return builtin_type_int64;
> >>> else
> >>> /* 32-bit ISA. */
> >>> return builtin_type_int32;
> >
> >
> >Would you mind clarifying the reason for having mips_regsize, which is
> >used in a number of other places, return a regsize based on the ISA?
>
> Hasn't this all come up before?
Yes, but obviously it hasn't been resolved :) I've dropped it a couple
of times - got distracted.
> It's the register size of the underlying ISA, on top of which the ABI is
> implemented. I think I'll rename mips_regsize and mips_saved_regsize to
> clarify this.
Please.
> >This change to mips_register_type conveys the fact that we've only got
> >32 bits of data. But we'll choose to print (in info registers) a
> >64-bit wide field for each GPR if the binary is tagged E_MIPS_ARCH_64 |
> >E_MIPS_ABI_EABI32, and a 32-bit field if it's tagged E_MIPS_ARCH_2 |
> >E_MIPS_ABI_EABI32. Conceptually, I think we're interested in some
> >combination of the available register size (-> a property of the target)
> >and the size of registers known to the inferior program (-> unclear mix
> >of its ABI and ISA).
>
> It does? With the above it should always print a 32-bit GPR reflecting
> the 32-bit ABI. If you think it should display something else, look at
> user-regs which lets you implement registers using the frame register
> values (something psuedo registers can't handle).
It makes decisions based on mips_regsize. See print_gp_register_row.
So does mips32_heuristic_proc_desc; which has probably been converted
incorrectly at some point in the past, since it takes "8 - mips_regsize
(current_gdbarch)" and wants 4 for N32. I think that whole block of
code is bogus.
Hmm, I was just using print_gp_register_row as an example - but it
turns out to be the only example. Only the two functions above and
mips_register_type reference mips_regsize now - and a bunch of NetBSD
specific code which is almost certainly wrong. With the functions
renamed, I guess it'll be much easier to spot the errors.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer