Re: [PATCH 3/3] gdb: remove target_ops parameter from gdbarch_core_read_description

[John Baldwin <jhb@FreeBSD.org>]

On 11/28/22 6:50 PM, Simon Marchi via Gdb-patches wrote:
> Following the previous patch ("gdb: change order of core_target
> initialization"), it is no longer necessary for the core target to pass
> a pointer to itself to gdbarch_core_read_description.  Implementations
> of this method can just do regular calls to target_read_auxv, through
> the inferior target stack.
> 
> This allows removing the target_ops parameter in
> gdbarch_core_read_description and a bunch of functions called
> downstream.  Some auxv-related functions received the auxv data as a
> parameter, since they could not assume it could be read from the current
> inferior, that is also no longer needed.
> 
> Regression tested.  I also tested manually against an AArch64 MTE test
> case that Luis Machado sent me a while ago when we were working on this
> auxv caching issue, the desired behavior of reporting the MTE tags when
> opening the code still worked.
> 
> Change-Id: I1e00361209028e9b65dde085d383cf950a7b5e3a
> ---
>   gdb/aarch64-fbsd-tdep.c   |  3 +--
>   gdb/aarch64-linux-tdep.c  |  8 +++-----
>   gdb/amd64-fbsd-tdep.c     |  4 +---
>   gdb/amd64-linux-tdep.c    |  4 +---
>   gdb/arc-linux-tdep.c      |  4 +---
>   gdb/arm-fbsd-tdep.c       | 24 +++++-------------------
>   gdb/arm-fbsd-tdep.h       | 15 +++++----------
>   gdb/arm-linux-tdep.c      |  7 ++-----
>   gdb/auxv.c                | 11 ++---------
>   gdb/auxv.h                |  4 ----
>   gdb/corelow.c             |  2 +-
>   gdb/gdbarch-components.py |  2 +-
>   gdb/gdbarch-gen.h         |  4 ++--
>   gdb/gdbarch.c             |  4 ++--
>   gdb/i386-fbsd-tdep.c      |  4 +---
>   gdb/i386-linux-tdep.c     |  4 +---
>   gdb/linux-tdep.c          | 24 ++++++++++--------------
>   gdb/linux-tdep.h          | 14 ++++++--------
>   gdb/mips-linux-tdep.c     |  4 +---
>   gdb/ppc-linux-tdep.c      |  7 ++-----
>   gdb/s390-linux-tdep.c     |  6 ++----
>   21 files changed, 50 insertions(+), 109 deletions(-)
> 
> diff --git a/gdb/arm-fbsd-tdep.c b/gdb/arm-fbsd-tdep.c
> index 75ee08eba506..4ea238de7c7f 100644
> --- a/gdb/arm-fbsd-tdep.c
> +++ b/gdb/arm-fbsd-tdep.c
> @@ -215,10 +215,11 @@ arm_fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
>   /* See arm-fbsd-tdep.h.  */
>   
>   const struct target_desc *
> -arm_fbsd_read_description_auxv (const gdb::optional<gdb::byte_vector> &auxv,
> -				target_ops *target, gdbarch *gdbarch, bool tls)
> +arm_fbsd_read_description_auxv (gdbarch *gdbarch, bool tls)
>   {
>     CORE_ADDR arm_hwcap = 0;
> +  gdb::optional<gdb::byte_vector> auxv = target_read_auxv ();
> +  target_ops *target = current_inferior ()->top_target ();
>   
>     if (!auxv.has_value ()
>         || target_auxv_search (*auxv, target, gdbarch, AT_FREEBSD_HWCAP,
> @@ -239,29 +240,14 @@ arm_fbsd_read_description_auxv (const gdb::optional<gdb::byte_vector> &auxv,
>     return arm_read_description (ARM_FP_TYPE_NONE, tls);
>   }
>   
> -/* See arm-fbsd-tdep.h.  */
> -
> -const struct target_desc *
> -arm_fbsd_read_description_auxv (bool tls)
> -{
> -  gdb::optional<gdb::byte_vector> auxv = target_read_auxv ();
> -  return arm_fbsd_read_description_auxv (auxv,
> -					 current_inferior ()->top_target (),
> -					 current_inferior ()->gdbarch,
> -					 tls);
> -}
> -

This function is used by arm-fbsd-nat.c in the read_description target
method.  Probably that function just needs to be updated to pass in the
gdbarch explicitly rather than keeping this wrapper method though:

diff --git a/gdb/arm-fbsd-nat.c b/gdb/arm-fbsd-nat.c
index 340b8e0d710..0ed3104d12d 100644
--- a/gdb/arm-fbsd-nat.c
+++ b/gdb/arm-fbsd-nat.c
@@ -96,7 +96,7 @@ arm_fbsd_nat_target::read_description ()
  #ifdef PT_GETREGSET
    tls = have_regset (inferior_ptid, NT_ARM_TLS) != 0;
  #endif
-  desc = arm_fbsd_read_description_auxv (tls);
+  desc = arm_fbsd_read_description_auxv (current_inferior ()->gdbarch, tls);
    if (desc == NULL)
      desc = this->beneath ()->read_description ();
    return desc;

-- 
John Baldwin