[PATCH 22/24] gdb: migrate arm to gdbarch_pseudo_register_read_value

Simon Marchi
2023-11-08T05:26:59Z

From: Simon Marchi <simon.marchi@efficios.com>

Make arm use the "newer" gdbarch_pseudo_register_read_value. This fixes
reading pseudo registers in non-current frames on that architecture.

Change-Id: Ic4d3d5d96957a4addfa3443c7b567dc4a31794a9
---
gdb/arm-tdep.c | 76 +++++++++++++++++++++++++++++---------------------
1 file changed, 44 insertions(+), 32 deletions(-)

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index cd4c760c2ff4..9bf51485b800 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -9816,61 +9816,73 @@ arm_neon_quad_read (struct gdbarch *gdbarch, readable_regcache *regcache,
return REG_VALID;
}

-/* Read the contents of the MVE pseudo register REGNUM and store it
- in BUF. */
+/* Read the contents of a NEON quad register, by reading from two double
+ registers, and return it as a value. QUAD_REG_INDEX is the index of the quad
+ register, in [0, 15]. */

-static enum register_status
-arm_mve_pseudo_read (struct gdbarch *gdbarch, readable_regcache *regcache,
- int regnum, gdb_byte *buf)
+static value *
+arm_neon_quad_read_value (gdbarch *gdbarch, frame_info_ptr next_frame,
+ int pseudo_reg_num, int quad_reg_index)
+{
+ 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.c_str (),
+ raw_reg_name.length ());
+
+ return pseudo_from_concat_raw (next_frame, pseudo_reg_num, double_regnum,
+ double_regnum + 1);
+}
+
+/* Read the contents of the MVE pseudo register REGNUM and return it as a
+ value. */
+static value *
+arm_mve_pseudo_read_value (gdbarch *gdbarch, frame_info_ptr next_frame,
+ int pseudo_reg_num)
{
arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);

/* P0 is the first 16 bits of VPR. */
- return regcache->raw_read_part (tdep->mve_vpr_regnum, 0, 2, buf);
+ return pseudo_from_raw_part (next_frame, pseudo_reg_num,
+ tdep->mve_vpr_regnum, 0);
}

-static enum register_status
-arm_pseudo_read (struct gdbarch *gdbarch, readable_regcache *regcache,
- int regnum, gdb_byte *buf)
+static value *
+arm_pseudo_read_value (gdbarch *gdbarch, frame_info_ptr next_frame,
+ const int pseudo_reg_num)
{
- 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. */
- return arm_neon_quad_read (gdbarch, regcache,
- regnum - tdep->q_pseudo_base, buf);
+ return arm_neon_quad_read_value (gdbarch, next_frame, pseudo_reg_num,
+ pseudo_reg_num - tdep->q_pseudo_base);
}
- else if (is_mve_pseudo (gdbarch, regnum))
- return arm_mve_pseudo_read (gdbarch, regcache, regnum, buf);
+ else if (is_mve_pseudo (gdbarch, pseudo_reg_num))
+ return arm_mve_pseudo_read_value (gdbarch, next_frame, pseudo_reg_num);
else
{
- enum register_status status;
+ int s_reg_index = pseudo_reg_num - tdep->s_pseudo_base;

- regnum -= 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 ());

- status = regcache->raw_read (double_regnum, reg_buf);
- if (status == REG_VALID)
- memcpy (buf, reg_buf + offset, 4);
- return status;
+ return pseudo_from_raw_part (next_frame, pseudo_reg_num, double_regnum,
+ offset);
}
}

@@ -10905,7 +10917,7 @@ arm_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
if (tdep->have_s_pseudos || have_mve || have_pacbti)
{
set_gdbarch_num_pseudo_regs (gdbarch, num_pseudos);
- set_gdbarch_pseudo_register_read (gdbarch, arm_pseudo_read);
+ set_gdbarch_pseudo_register_read_value (gdbarch, arm_pseudo_read_value);
set_gdbarch_deprecated_pseudo_register_write (gdbarch, arm_pseudo_write);
}

--
2.42.1