Re: [PATCH 1/3] Add sp_regnum_from_eax and pc_regnum_from_eax

Mark Kettenis
2012-07-04T19:53:34Z

> Date: Tue, 3 Jul 2012 16:55:59 -0700
> From: "H.J. Lu" <hjl.tools@gmail.com>
>
> On Tue, Jul 3, 2012 at 12:14 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> > On Tue, Jul 3, 2012 at 10:35 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> >> On Tue, Jul 3, 2012 at 8:54 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> >>> On Tue, Jul 3, 2012 at 7:08 AM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> >>>>> Date: Thu, 21 Jun 2012 11:14:52 -0700
> >>>>> From: "H.J. Lu" <hongjiu.lu@intel.com>
> >>>>>
> >>>>> Hi,
> >>>>>
> >>>>> Here are the first of the last 3 patches for x32 support in GDB. This
> >>>>> patch maps $pc to $eip and $sp to $esp for x32. OK to install?
> >>>>
> >>>> The pseudo register handling code is getting too complex :(. I feel
> >>>> that hiding the set_gdbarch_pc_regnum() and set_gdbarch_sp_regnum()
> >>>> calls in i386-tdep.c isn't the right approach. But I haven't found a
> >>>> better one yet :(.
> >>>>
> >>>
> >>> One possibility is to set pc/sp to register name instead of regnum.
> >>> i386_gdbarch_init can map them to regnum after all pseudo registers
> >>> are finalized.
> >>>
> >>> --
> >>> H.J.
> >>
> >> How about this patch? I can also change amd64 and i386
> >> to use "rsp/"rsp"/"esp"/"eip".
> >>
> >
> > This patch sets SP?PC regnums from register names.
> >
> >
>
> Here is another approach to set SP/PC regnums after
> setting up pseudo registers.

I've come to the conclusion that the speudo register handling in
i386/amd64 needs some serious surgery. I think your origional diff:

http://sourceware.org/ml/gdb-patches/2012-06/msg00664.html

is the least invasive. Can you commit that one?

> --
> H.J.
> ---
> * amd64-tdep.c (amd64_init_abi): Set sp_regnum to AMD64_RSP_REGNUM
> and set pc_regnum to AMD64_RIP_REGNUM. Don't call
> set_gdbarch_sp_regnum nor set_gdbarch_pc_regnum here.
> (amd64_x32_init_abi): Set sp_regnum to -AMD64_RSP_REGNUM and set
> pc_regnum to -AMD64_RIP_REGNUM.
>
> * i386-tdep.c (i386_gdbarch_init): Set sp_regnum to I386_ESP_REGNUM
> and set pc_regnum to I386_EIP_REGNUM. Call set_gdbarch_sp_regnum
> and set_gdbarch_pc_regnum after setting up pseudo registers.
>
> * i386-tdep.h (gdbarch_tdep): Add sp_regnum and pc_regnum.
>
> diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
> index 8ae1142..df0df08 100644
> --- a/gdb/amd64-tdep.c
> +++ b/gdb/amd64-tdep.c
> @@ -2846,8 +2846,8 @@ amd64_init_abi (struct gdbarch_info info, struct
> gdbarch *gdbarch)
> set_gdbarch_num_regs (gdbarch, AMD64_NUM_REGS);
>
> /* Register numbers of various important registers. */
> - set_gdbarch_sp_regnum (gdbarch, AMD64_RSP_REGNUM); /* %rsp */
> - set_gdbarch_pc_regnum (gdbarch, AMD64_RIP_REGNUM); /* %rip */
> + tdep->sp_regnum = AMD64_RSP_REGNUM; /* %rsp */
> + tdep->pc_regnum = AMD64_RIP_REGNUM; /* %rip */
> set_gdbarch_ps_regnum (gdbarch, AMD64_EFLAGS_REGNUM); /* %eflags */
> set_gdbarch_fp0_regnum (gdbarch, AMD64_ST0_REGNUM); /* %st(0) */
>
> @@ -2946,6 +2946,9 @@ amd64_x32_init_abi (struct gdbarch_info info,
> struct gdbarch *gdbarch)
> tdesc = tdesc_x32;
> tdep->tdesc = tdesc;
>
> + tdep->sp_regnum = -AMD64_RSP_REGNUM; /* %esp */
> + tdep->pc_regnum = -AMD64_RIP_REGNUM; /* %eip */
> +
> tdep->num_dword_regs = 17;
> set_tdesc_pseudo_register_type (gdbarch, amd64_x32_pseudo_register_type);
>
> diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
> index fd5969d..a287785 100644
> --- a/gdb/i386-tdep.c
> +++ b/gdb/i386-tdep.c
> @@ -7671,8 +7671,8 @@ i386_gdbarch_init (struct gdbarch_info info,
> struct gdbarch_list *arches)
> set_gdbarch_long_double_bit (gdbarch, 96);
>
> /* Register numbers of various important registers. */
> - set_gdbarch_sp_regnum (gdbarch, I386_ESP_REGNUM); /* %esp */
> - set_gdbarch_pc_regnum (gdbarch, I386_EIP_REGNUM); /* %eip */
> + tdep->sp_regnum = I386_ESP_REGNUM; /* %esp */
> + tdep->pc_regnum = I386_EIP_REGNUM; /* %eip */
> set_gdbarch_ps_regnum (gdbarch, I386_EFLAGS_REGNUM); /* %eflags */
> set_gdbarch_fp0_regnum (gdbarch, I386_ST0_REGNUM); /* %st(0) */
>
> @@ -7871,6 +7871,16 @@ i386_gdbarch_init (struct gdbarch_info info,
> struct gdbarch_list *arches)
> else
> tdep->mm0_regnum = -1;
>
> + /* Set up SP and PC register numbers. */
> + set_gdbarch_sp_regnum (gdbarch,
> + tdep->sp_regnum >= 0
> + ? tdep->sp_regnum
> + : tdep->eax_regnum - tdep->sp_regnum);
> + set_gdbarch_pc_regnum (gdbarch,
> + tdep->pc_regnum >= 0
> + ? tdep->pc_regnum
> + : tdep->eax_regnum - tdep->pc_regnum);
> +
> /* Hook in the legacy prologue-based unwinders last (fallback). */
> frame_unwind_append_unwinder (gdbarch, &i386_stack_tramp_frame_unwind);
> frame_unwind_append_unwinder (gdbarch, &i386_sigtramp_frame_unwind);
> diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
> index 5f233f5..99b5f42 100644
> --- a/gdb/i386-tdep.h
> +++ b/gdb/i386-tdep.h
> @@ -149,6 +149,14 @@ struct gdbarch_tdep
> of pseudo dword register support. */
> int eax_regnum;
>
> + /* Register number for SP. If it < 0, SP register number is
> + eax_regnum - sp_regnum. */
> + int sp_regnum;
> +
> + /* Register number for PC. If it < 0, PC register number is
> + eax_regnum - pc_regnum. */
> + int pc_regnum;
> +
> /* Number of core registers. */
> int num_core_regs;
>