Re: [PATCH v2 23/24] gdb: migrate arm to new gdbarch_pseudo_register_write

[Luis Machado <luis.machado@arm.com>]

On 11/24/23 21:26, Simon Marchi wrote:
> Make arm use the new gdbarch_pseudo_register_write.  This fixes writing
> pseudo registers to non-current frames for that architecture.
> 
> Change-Id: Icb2a649ab6394817844230e9e94c3d0564d2f765
> Reviewed-By: John Baldwin <jhb@FreeBSD.org>
> ---
>  gdb/arm-tdep.c | 62 +++++++++++++++++++++++++++++---------------------
>  1 file changed, 36 insertions(+), 26 deletions(-)
> 
> diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
> index cded66c91454..4e34203243af 100644
> --- a/gdb/arm-tdep.c
> +++ b/gdb/arm-tdep.c
> @@ -9908,57 +9908,67 @@ arm_neon_quad_write (struct gdbarch *gdbarch, struct regcache *regcache,
>    regcache->raw_write (double_regnum + 1, buf + 8);
>  }
>  
> +static void
> +arm_neon_quad_write (gdbarch *gdbarch, frame_info_ptr next_frame,
> +		     int quad_reg_index, gdb::array_view<const gdb_byte> buf)
> +{
> +  std::string raw_reg_name = string_printf ("d%d", quad_reg_index << 1);
> +  int double_regnum
> +    = user_reg_map_name_to_regnum (gdbarch, raw_reg_name.data (),
> +				   raw_reg_name.length ());
> +
> +  pseudo_to_concat_raw (next_frame, buf, double_regnum, double_regnum + 1);
> +}
> +
>  /* Store the contents of BUF to the MVE pseudo register REGNUM.  */
>  
>  static void
> -arm_mve_pseudo_write (struct gdbarch *gdbarch, struct regcache *regcache,
> -		      int regnum, const gdb_byte *buf)
> +arm_mve_pseudo_write (gdbarch *gdbarch, frame_info_ptr next_frame,
> +		      int pseudo_reg_num, gdb::array_view<const gdb_byte> buf)
>  {
>    arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);
>  
>    /* P0 is the first 16 bits of VPR.  */
> -  regcache->raw_write_part (tdep->mve_vpr_regnum, 0, 2, buf);
> +  pseudo_to_raw_part(next_frame, buf, tdep->mve_vpr_regnum, 0);
>  }
>  
>  static void
> -arm_pseudo_write (struct gdbarch *gdbarch, struct regcache *regcache,
> -		  int regnum, const gdb_byte *buf)
> +arm_pseudo_write (gdbarch *gdbarch, frame_info_ptr next_frame,
> +		  const int pseudo_reg_num,
> +		  gdb::array_view<const gdb_byte> buf)
>  {
> -  const int num_regs = gdbarch_num_regs (gdbarch);
> -  char name_buf[4];
> -  gdb_byte reg_buf[8];
> -  int offset, double_regnum;
>    arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);
>  
> -  gdb_assert (regnum >= num_regs);
> +  gdb_assert (pseudo_reg_num >= gdbarch_num_regs (gdbarch));
>  
> -  if (is_q_pseudo (gdbarch, regnum))
> +  if (is_q_pseudo (gdbarch, pseudo_reg_num))
>      {
>        /* Quad-precision register.  */
> -      arm_neon_quad_write (gdbarch, regcache,
> -			   regnum - tdep->q_pseudo_base, buf);
> +      arm_neon_quad_write (gdbarch, next_frame,
> +			   pseudo_reg_num - tdep->q_pseudo_base, buf);
>      }
> -  else if (is_mve_pseudo (gdbarch, regnum))
> -    arm_mve_pseudo_write (gdbarch, regcache, regnum, buf);
> +  else if (is_mve_pseudo (gdbarch, pseudo_reg_num))
> +    arm_mve_pseudo_write (gdbarch, next_frame, pseudo_reg_num, buf);
>    else
>      {
> -      regnum -= tdep->s_pseudo_base;
> +      int s_reg_index = pseudo_reg_num - tdep->s_pseudo_base;
> +
>        /* Single-precision register.  */
> -      gdb_assert (regnum < 32);
> +      gdb_assert (s_reg_index < 32);
>  
>        /* s0 is always the least significant half of d0.  */
> +      int offset;
>        if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
> -	offset = (regnum & 1) ? 0 : 4;
> +	offset = (s_reg_index & 1) ? 0 : 4;
>        else
> -	offset = (regnum & 1) ? 4 : 0;
> +	offset = (s_reg_index & 1) ? 4 : 0;
>  
> -      xsnprintf (name_buf, sizeof (name_buf), "d%d", regnum >> 1);
> -      double_regnum = user_reg_map_name_to_regnum (gdbarch, name_buf,
> -						   strlen (name_buf));
> +      std::string raw_reg_name = string_printf ("d%d", s_reg_index >> 1);
> +      int double_regnum
> +	= user_reg_map_name_to_regnum (gdbarch, raw_reg_name.c_str (),
> +				       raw_reg_name.length ());
>  
> -      regcache->raw_read (double_regnum, reg_buf);
> -      memcpy (reg_buf + offset, buf, 4);
> -      regcache->raw_write (double_regnum, reg_buf);
> +      pseudo_to_raw_part (next_frame, buf, double_regnum, offset);
>      }
>  }
>  
> @@ -10918,7 +10928,7 @@ arm_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
>      {
>        set_gdbarch_num_pseudo_regs (gdbarch, num_pseudos);
>        set_gdbarch_pseudo_register_read_value (gdbarch, arm_pseudo_read_value);
> -      set_gdbarch_deprecated_pseudo_register_write (gdbarch, arm_pseudo_write);
> +      set_gdbarch_pseudo_register_write (gdbarch, arm_pseudo_write);
>      }
>  
>    /* Add standard register aliases.  We add aliases even for those

LGTM.

Approved-by: Luis Machado <luis.machado@arm.com>