Re: [PATCH 24/24] gdb/testsuite: add tests for unwinding of pseudo registers

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

On 12/1/23 16:27, Simon Marchi wrote:
> From: Simon Marchi <simon.marchi@polymtl.ca>
> 
> New in v2:
> 
>  - Switched to using x19/w19 in the aarch64 test
> 
> This patch adds tests to exercise the previous patches' changes.
> 
> All three tests:
> 
>  - aarch64-pseudo-unwind
>  - amd64-pseudo-unwind
>  - arm-pseudo-unwind
> 
> follow the same pattern, just with different registers.
> 
> The other test, arm-pseudo-unwind-legacy, tests the special case where
> the unwind information contains an entry for a register considered a
> pseudo-register by GDB.
> 
> Change-Id: Ic29ac040c5eb087b4a0d79f9d02f65b7979df30f
> Reviewed-By: John Baldwin <jhb@FreeBSD.org>
> Reviewed-by: Luis Machado <luis.machado@arm.com>
> ---
>  .../gdb.arch/aarch64-pseudo-unwind-asm.S      | 82 +++++++++++++++++
>  .../gdb.arch/aarch64-pseudo-unwind.c          | 33 +++++++
>  .../gdb.arch/aarch64-pseudo-unwind.exp        | 88 ++++++++++++++++++
>  .../gdb.arch/amd64-pseudo-unwind-asm.S        | 66 ++++++++++++++
>  gdb/testsuite/gdb.arch/amd64-pseudo-unwind.c  | 33 +++++++
>  .../gdb.arch/amd64-pseudo-unwind.exp          | 91 +++++++++++++++++++
>  .../gdb.arch/arm-pseudo-unwind-asm.S          | 79 ++++++++++++++++
>  .../gdb.arch/arm-pseudo-unwind-legacy-asm.S   | 84 +++++++++++++++++
>  .../gdb.arch/arm-pseudo-unwind-legacy.c       | 33 +++++++
>  .../gdb.arch/arm-pseudo-unwind-legacy.exp     | 86 ++++++++++++++++++
>  gdb/testsuite/gdb.arch/arm-pseudo-unwind.c    | 33 +++++++
>  gdb/testsuite/gdb.arch/arm-pseudo-unwind.exp  | 88 ++++++++++++++++++
>  12 files changed, 796 insertions(+)
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-pseudo-unwind-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.c
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.exp
>  create mode 100644 gdb/testsuite/gdb.arch/amd64-pseudo-unwind-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/amd64-pseudo-unwind.c
>  create mode 100644 gdb/testsuite/gdb.arch/amd64-pseudo-unwind.exp
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.c
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.exp
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind.c
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind.exp
> 
> diff --git a/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind-asm.S b/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind-asm.S
> new file mode 100644
> index 000000000000..575ed75ae9f5
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind-asm.S
> @@ -0,0 +1,82 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +.section .note.GNU-stack,"",%progbits
> +
> +.data
> +value_callee:
> +.quad 0x2021222324252627
> +value_caller:
> +.quad 0x1011121314151617
> +
> +.text
> +.global callee
> +callee:
> +	/* Standard prologue:
> +	    - push fp (x29) and lr (x30) to the stack.
> +	    - mov sp to fp  */
> +.cfi_startproc
> +	stp x29, x30, [sp, -16]!
> +.cfi_def_cfa 29, 16
> +.cfi_offset 29, -16
> +.cfi_offset 30, -8
> +	mov x29, sp
> +
> +	/* Save caller's x19 value on the stack.  */
> +.cfi_offset 19, -32
> +	str x19, [sp, -16]!
> +
> +	/* Put our own x19 value.  */
> +	adr x0, value_callee
> +	ldr x19, [x0]
> +
> +break_here_asm:
> +
> +	/* Restore caller's x19 value.  */
> +	ldr x19, [sp], 16
> +
> +	/* Standard epilogue:
> +	    - pop fp (x29) and lr (x30) from the stack  */
> +	ldp x29, x30, [sp], 16
> +	ret
> +.cfi_endproc
> +
> +
> +.global caller
> +caller:
> +	/* Standard prologue.  */
> +.cfi_startproc
> +	stp x29, x30, [sp, -16]!
> +.cfi_def_cfa 29, 16
> +.cfi_offset x29, -16
> +.cfi_offset x30, -8
> +	add x29, sp, 0
> +
> +	/* Put our own x19 value.  */
> +	adr x0, value_caller
> +	ldr x19, [x0]
> +
> +	/* Call callee.  */
> +	bl callee
> +
> +	/* Store our x19 value in x0 to return it.  */
> +	mov x0, x19
> +
> +	/* Standard epilogue.  */
> +	ldp x29, x30, [sp], 16
> +	ret
> +.cfi_endproc
> diff --git a/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.c b/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.c
> new file mode 100644
> index 000000000000..d18876fe3be3
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.c
> @@ -0,0 +1,33 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdint.h>
> +
> +uint64_t caller (void);
> +
> +static void
> +break_here_c (uint64_t value)
> +{
> +}
> +
> +int
> +main (void)
> +{
> +  uint64_t value = caller ();
> +  break_here_c (value);
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.exp b/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.exp
> new file mode 100644
> index 000000000000..62b3f8c4337c
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.exp
> @@ -0,0 +1,88 @@
> +# Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# This test is equivalent to amd64-pseudo-unwind, but specific to AArch64.  We
> +# use the raw register x19 which is 64 bits long and pseudo register w19, which
> +# is the bottom half of x19.
> +
> +if { ![istarget aarch64-*-* ] } {
> +    verbose "Skipping aarch64 pseudo register unwind."
> +    return
> +}
> +
> +standard_testfile aarch64-pseudo-unwind.c aarch64-pseudo-unwind-asm.S
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile} \
> +	"${srcfile} ${srcfile2}" {debug}] } {
> +    return -1
> +}
> +
> +clean_restart ${binfile}
> +
> +if ![runto_main] then {
> +    fail "could not run to main"
> +}
> +
> +gdb_breakpoint break_here_asm temporary
> +gdb_continue_to_breakpoint "continue to callee"
> +
> +# Verify the value of x19/w19 in the inner frame (callee).
> +with_test_prefix "callee, before change" {
> +    gdb_test "p/x \$x19" " = 0x2021222324252627"
> +    gdb_test "p/x \$w19" " = 0x24252627"
> +}
> +
> +# Verify that we can change the value of the pseudo register (w19) in the inner
> +# frame (callee).
> +gdb_test_no_output "set \$w19 = 0x34353637"
> +
> +# Verify the value of x19/w19 in the inner frame (callee) after the change.
> +with_test_prefix "callee, after change" {
> +    gdb_test "p/x \$x19" " = 0x34353637"
> +    gdb_test "p/x \$w19" " = 0x34353637"
> +}
> +
> +# Go up one frame (to caller) and do the same.
> +gdb_test "up"
> +
> +# Verify the value of x19/w19 in the outer frame (caller).
> +with_test_prefix "caller, before change" {
> +    gdb_test "p/x \$x19" " = 0x1011121314151617"
> +    gdb_test "p/x \$w19" " = 0x14151617"
> +}
> +
> +# Verify that we can change the value of the pseudo register (w19) in the outer
> +# frame (caller).
> +gdb_test_no_output "set \$w19 = 0x44454647"
> +
> +# Verify the value of x19/w19 in the outer frame (caller) after the change.
> +with_test_prefix "caller, after change" {
> +    gdb_test "p/x \$x19" " = 0x44454647"
> +    gdb_test "p/x \$w19" " = 0x44454647"
> +}
> +
> +# Go back to frame 0 (callee), check that the change to the outer frame didn't
> +# mess up anything there.
> +gdb_test "down"
> +with_test_prefix "callee, after change in caller" {
> +    gdb_test "p/x \$x19" " = 0x34353637"
> +    gdb_test "p/x \$w19" " = 0x34353637"
> +}
> +
> +# Verify that the value of the saved x19 we changed is correctly seen by the
> +# inferior.
> +gdb_breakpoint break_here_c temporary
> +gdb_continue_to_breakpoint "continue to break_here_c"
> +gdb_test "p/x value" " = 0x44454647"
> diff --git a/gdb/testsuite/gdb.arch/amd64-pseudo-unwind-asm.S b/gdb/testsuite/gdb.arch/amd64-pseudo-unwind-asm.S
> new file mode 100644
> index 000000000000..c306b82e4864
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/amd64-pseudo-unwind-asm.S
> @@ -0,0 +1,66 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +.section .note.GNU-stack,"",%progbits
> +
> +.text
> +.global callee
> +callee:
> +	/* Standard prologue.  */
> +.cfi_startproc
> +	push %rbp
> +.cfi_def_cfa rbp, 16
> +	mov %rsp, %rbp
> +
> +	/* Save caller's rbx value on the stack.  */
> +.cfi_offset rbx, -24
> +	push %rbx
> +
> +	/* Put our own rbx value.  */
> +	mov $0x2021222324252627, %rbx
> +break_here_asm:
> +
> +	/* Restore caller's rbx value.  */
> +	pop %rbx
> +
> +	/* Standard epilogue.  */
> +	pop %rbp
> +	ret
> +.cfi_endproc
> +
> +
> +.global caller
> +caller:
> +.cfi_startproc
> +	/* Standard prologue.  */
> +	push %rbp
> +.cfi_def_cfa_offset 16
> +	mov %rsp, %rbp
> +
> +	/* Put our own rbx value.  */
> +	mov $0x1011121314151617, %rbx
> +
> +	/* Call callee.  */
> +	call callee
> +
> +	/* Store our rbx value in rax to return it.  */
> +	mov %rbx, %rax
> +
> +	/* Standard epilogue.  */
> +	pop %rbp
> +	ret
> +.cfi_endproc
> diff --git a/gdb/testsuite/gdb.arch/amd64-pseudo-unwind.c b/gdb/testsuite/gdb.arch/amd64-pseudo-unwind.c
> new file mode 100644
> index 000000000000..d18876fe3be3
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/amd64-pseudo-unwind.c
> @@ -0,0 +1,33 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdint.h>
> +
> +uint64_t caller (void);
> +
> +static void
> +break_here_c (uint64_t value)
> +{
> +}
> +
> +int
> +main (void)
> +{
> +  uint64_t value = caller ();
> +  break_here_c (value);
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.arch/amd64-pseudo-unwind.exp b/gdb/testsuite/gdb.arch/amd64-pseudo-unwind.exp
> new file mode 100644
> index 000000000000..45e9a3c96224
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/amd64-pseudo-unwind.exp
> @@ -0,0 +1,91 @@
> +# Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# This test verifies that we can read and write the value of a pseudo register
> +# in unwound frames.  For the test, we choose one raw register, rbx, and one
> +# pseudo register that is backed by rbx, ebx.  We have two frames (the inner one,
> +# #0 and the outer one, #1) that each set a value for rbx.  We verify that we
> +# can read both rbx and ebx correctly for each frame, and that when we write to
> +# ebx, rbx for that frame is correctly updated.
> +
> +if { ![istarget x86_64-*-* ] || ![is_lp64_target] } {
> +    verbose "Skipping amd64 pseudo register unwind."
> +    return
> +}
> +
> +standard_testfile amd64-pseudo-unwind.c amd64-pseudo-unwind-asm.S
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile} \
> +	"${srcfile} ${srcfile2}" {debug}] } {
> +    return -1
> +}
> +
> +clean_restart ${binfile}
> +
> +if ![runto_main] then {
> +    fail "could not run to main"
> +}
> +
> +gdb_breakpoint break_here_asm temporary
> +gdb_continue_to_breakpoint "continue to callee"
> +
> +# Verify the value of rbx/ebx in the inner frame (callee).
> +with_test_prefix "callee, before change" {
> +    gdb_test "p/x \$rbx" " = 0x2021222324252627"
> +    gdb_test "p/x \$ebx" " = 0x24252627"
> +}
> +
> +# Verify that we can change the value of the pseudo register (ebx) in the inner
> +# frame (callee).
> +gdb_test_no_output "set \$ebx = 0x34353637"
> +
> +# Verify the value of rbx/ebx in the inner frame (callee) after the change.
> +with_test_prefix "callee, after change" {
> +    gdb_test "p/x \$rbx" " = 0x2021222334353637"
> +    gdb_test "p/x \$ebx" " = 0x34353637"
> +}
> +
> +# Go up one frame, and do the same.
> +gdb_test "up"
> +
> +# Verify the value of rbx/ebx in the outer frame (caller).
> +with_test_prefix "caller, before change" {
> +    gdb_test "p/x \$rbx" " = 0x1011121314151617"
> +    gdb_test "p/x \$ebx" " = 0x14151617"
> +}
> +
> +# Verify that we can change the value of the pseudo register (ebx) in the outer
> +# frame (caller).
> +gdb_test_no_output "set \$ebx = 0x44454647"
> +
> +# Verify the value of rbx/ebx in the outer frame (caller) after the change.
> +with_test_prefix "caller, after change" {
> +    gdb_test "p/x \$rbx" " = 0x1011121344454647"
> +    gdb_test "p/x \$ebx" " = 0x44454647"
> +}
> +
> +# Go back to frame 0 (callee), check that the change to the outer frame didn't
> +# mess up anything there.
> +gdb_test "down"
> +with_test_prefix "callee, after change in caller" {
> +    gdb_test "p/x \$rbx" " = 0x2021222334353637"
> +    gdb_test "p/x \$ebx" " = 0x34353637"
> +}
> +
> +# Verify that the value of the saved rbx we changed is correctly seen by the
> +# inferior.
> +gdb_breakpoint break_here_c temporary
> +gdb_continue_to_breakpoint "continue to break_here_c"
> +gdb_test "p/x value" " = 0x1011121344454647"
> diff --git a/gdb/testsuite/gdb.arch/arm-pseudo-unwind-asm.S b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-asm.S
> new file mode 100644
> index 000000000000..0e5ad1b9bee1
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-asm.S
> @@ -0,0 +1,79 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +.section .note.GNU-stack,"",%progbits
> +
> +.data
> +value_callee:
> +.quad 0x2021222324252627
> +value_caller:
> +.quad 0x1011121314151617
> +
> +.text
> +.arm
> +.global callee
> +callee:
> +	/* Standard prologue.  */
> +.cfi_startproc
> +	push {fp, lr}
> +.cfi_def_cfa fp, 4
> +.cfi_offset fp, -8
> +.cfi_offset lr, -4
> +	add fp, sp, #4
> +
> +	/* Save caller's d8 value on the stack.  */
> +.cfi_offset d8, -16
> +	vpush {d8}
> +
> +	/* Put our own d8 value.  */
> +	ldr r0, =value_callee
> +	vldr d8, [r0]
> +break_here_asm:
> +
> +	/* Restore caller's d8 value.  */
> +	vpop {d8}
> +
> +	/* Standard epilogue.  */
> +	pop {fp, pc}
> +.cfi_endproc
> +
> +
> +.global caller
> +caller:
> +	/* Standard prologue.  */
> +.cfi_startproc
> +	push {fp, lr}
> +.cfi_def_cfa fp, 4
> +.cfi_offset fp, -8
> +.cfi_offset lr, -4
> +	add fp, sp, #4
> +
> +	/* Put our own d8 value.  */
> +	ldr r0, =value_caller
> +	vldr d8, [r0]
> +
> +	/* Call callee.  */
> +	bl callee
> +
> +	/* Store our d8 value in r0-r1 to return it.  */
> +	vpush {d8}
> +	pop {r0}
> +	pop {r1}
> +
> +	/* Standard epilogue.  */
> +	pop {fp, pc}
> +.cfi_endproc
> diff --git a/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy-asm.S b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy-asm.S
> new file mode 100644
> index 000000000000..786e79a0543e
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy-asm.S
> @@ -0,0 +1,84 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* The difference between this and arm-pseudo-unwind is that here, the CFI
> +   directives use the obsolete DWARF number for the s16 register (a
> +   pseudo-register in GDB), whereas arm-pseudo-unwind uses the number for the d8
> +   register (the underlying raw register for s16).  */
> +
> +.section .note.GNU-stack,"",%progbits
> +
> +.data
> +value_callee:
> +.quad 0x20212223
> +value_caller:
> +.quad 0x10111213
> +
> +.text
> +.arm
> +.global callee
> +callee:
> +.cfi_startproc
> +	/* Standard prologue.  */
> +	push {fp, lr}
> +.cfi_def_cfa fp, 4
> +.cfi_offset fp, -8
> +.cfi_offset lr, -4
> +	add fp, sp, #4
> +
> +	/* Save caller's s16 value on the stack.  */
> +.cfi_offset 80, -12
> +	vpush {s16}
> +
> +	/* Put our own s16 value.  */
> +	ldr r0, =value_callee
> +	vldr s16, [r0]
> +break_here_asm:
> +
> +	/* Restore caller's s16 value.  */
> +	vpop {s16}
> +
> +	/* Standard epilogue.  */
> +	pop {fp, pc}
> +.cfi_endproc
> +
> +
> +.global caller
> +caller:
> +.cfi_startproc
> +	/* Standard prologue.  */
> +	push {fp, lr}
> +.cfi_def_cfa fp, 4
> +.cfi_offset fp, -8
> +.cfi_offset lr, -4
> +	add fp, sp, #4
> +
> +	/* Put our own s16 value.  */
> +	ldr r0, =value_caller
> +	vldr s16, [r0]
> +
> +	/* Call callee.  */
> +	bl callee
> +
> +	/* Store our s16 value in r0-r1 to return it.  */
> +	vpush {s16}
> +	pop {r0}
> +	mov r1, #0
> +
> +	/* Standard epilogue.  */
> +	pop {fp, pc}
> +.cfi_endproc
> diff --git a/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.c b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.c
> new file mode 100644
> index 000000000000..d18876fe3be3
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.c
> @@ -0,0 +1,33 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdint.h>
> +
> +uint64_t caller (void);
> +
> +static void
> +break_here_c (uint64_t value)
> +{
> +}
> +
> +int
> +main (void)
> +{
> +  uint64_t value = caller ();
> +  break_here_c (value);
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.exp b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.exp
> new file mode 100644
> index 000000000000..c3d0979799dc
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.exp
> @@ -0,0 +1,86 @@
> +# Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# This test is in the same vein as amd64-pseudo-unwind, making sure we can
> +# read write pseudo registers in outer frames.  However, it tests a special
> +# case where the debug info includes unwind information for a pseudo register
> +# but not the underlying raw register.  This can happen for the pseudo register
> +# s16, which is the bottom half of the raw register d8.
> +#
> +# See "DWARF for the ARM architecture":
> +#   https://github.com/ARM-software/abi-aa/releases/download/2023Q3/aadwarf32.pdf
> +
> +if { ![istarget arm*-*-* ] } {
> +    verbose "Skipping arm pseudo register unwind."
> +    return
> +}
> +
> +standard_testfile arm-pseudo-unwind-legacy.c arm-pseudo-unwind-legacy-asm.S
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile} \
> +	"${srcfile} ${srcfile2}" {debug additional_flags=-marm}] } {
> +    return -1
> +}
> +
> +clean_restart ${binfile}
> +
> +if ![runto_main] then {
> +    fail "could not run to main"
> +}
> +
> +gdb_breakpoint break_here_asm temporary
> +gdb_continue_to_breakpoint "continue to callee"
> +
> +# Verify the value of s16 in the inner frame (callee).
> +with_test_prefix "callee, before change" {
> +    gdb_test "p/x \$s16" " = 0x20212223"
> +}
> +
> +# Verify that we can change the value of s16 in the inner frame (callee).
> +gdb_test_no_output "set \$s16 = 1.0"
> +
> +# Verify the value of s16 in the inner frame (callee) after the change.
> +with_test_prefix "callee, after change" {
> +    gdb_test "p/x \$s16" " = 0x3f800000"
> +}
> +
> +# Go up one frame, and do the same.
> +gdb_test "up"
> +
> +# Verify the value of s16 in the outer frame (caller).
> +with_test_prefix "caller, before change" {
> +    gdb_test "p/x \$s16" " = 0x10111213"
> +}
> +
> +# Verify that we can change the value of s16 in the outer frame (caller).
> +gdb_test_no_output "set \$s16 = 2.0"
> +
> +# Verify the value of s16 in the outer frame (caller) after the change.
> +with_test_prefix "caller, after change" {
> +    gdb_test "p/x \$s16" " = 0x40000000"
> +}
> +
> +# Go back to frame 0 (callee), check that the change to the outer frame didn't
> +# mess up anything there.
> +gdb_test "down"
> +with_test_prefix "callee, after change in caller" {
> +    gdb_test "p/x \$s16" " = 0x3f800000"
> +}
> +
> +# Verify that the value of the saved s16 we changed is correctly seen by the
> +# inferior.
> +gdb_breakpoint break_here_c temporary
> +gdb_continue_to_breakpoint "continue to break_here_c"
> +gdb_test "p/x value" " = 0x40000000"
> diff --git a/gdb/testsuite/gdb.arch/arm-pseudo-unwind.c b/gdb/testsuite/gdb.arch/arm-pseudo-unwind.c
> new file mode 100644
> index 000000000000..d18876fe3be3
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/arm-pseudo-unwind.c
> @@ -0,0 +1,33 @@
> +/* Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdint.h>
> +
> +uint64_t caller (void);
> +
> +static void
> +break_here_c (uint64_t value)
> +{
> +}
> +
> +int
> +main (void)
> +{
> +  uint64_t value = caller ();
> +  break_here_c (value);
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.arch/arm-pseudo-unwind.exp b/gdb/testsuite/gdb.arch/arm-pseudo-unwind.exp
> new file mode 100644
> index 000000000000..bfe81b7d5f21
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/arm-pseudo-unwind.exp
> @@ -0,0 +1,88 @@
> +# Copyright 2018-2023 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# This test is equivalent to amd64-pseudo-unwind, but specific to ARM.  We
> +# use the raw register d8 which is 64 bits long.  We use pseudo register s16,
> +# which is the low 32 bits of d8.
> +
> +if { ![istarget arm*-*-* ] } {
> +    verbose "Skipping arm pseudo register unwind."
> +    return
> +}
> +
> +standard_testfile arm-pseudo-unwind.c arm-pseudo-unwind-asm.S
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile} \
> +	"${srcfile} ${srcfile2}" {debug additional_flags=-marm}] } {
> +    return -1
> +}
> +
> +clean_restart ${binfile}
> +
> +if ![runto_main] then {
> +    fail "could not run to main"
> +}
> +
> +gdb_breakpoint break_here_asm temporary
> +gdb_continue_to_breakpoint "continue to callee"
> +
> +# Verify the value of d8/s16 in the inner frame (callee).
> +with_test_prefix "callee, before change" {
> +    gdb_test "p/x \$d8" " = 0x2021222324252627"
> +    gdb_test "p/x \$s16" " = 0x24252627"
> +}
> +
> +# Verify that we can change the value of the pseudo register (s16) in the inner
> +# frame (callee).
> +gdb_test_no_output "set \$s16 = 1.0"
> +
> +# Verify the value of d8/s16 in the inner frame (callee) after the change.
> +with_test_prefix "callee, after change" {
> +    gdb_test "p/x \$d8" " = 0x202122233f800000"
> +    gdb_test "p/x \$s16" " = 0x3f800000"
> +}
> +
> +# Go up one frame (to caller), and do the same.
> +gdb_test "up"
> +
> +# Verify the value of d8/s16 in the outer frame (caller).
> +with_test_prefix "caller, before change" {
> +    gdb_test "p/x \$d8" " = 0x1011121314151617"
> +    gdb_test "p/x \$s16" " = 0x14151617"
> +}
> +
> +# Verify that we can change the value of the pseudo register (s16) in the outer
> +# frame (caller).
> +gdb_test_no_output "set \$s16 = 2.0"
> +
> +# Verify the value of d8/s16 in the outer frame (caller) after the change.
> +with_test_prefix "caller, after change" {
> +    gdb_test "p/x \$d8" " = 0x1011121340000000"
> +    gdb_test "p/x \$s16" " = 0x40000000"
> +}
> +
> +# Go back to frame 0 (callee), check that the change to the outer frame didn't
> +# mess up anything there.
> +gdb_test "down"
> +with_test_prefix "callee, after change in caller" {
> +    gdb_test "p/x \$d8" " = 0x202122233f800000"
> +    gdb_test "p/x \$s16" " = 0x3f800000"
> +}
> +
> +# Verify that the value of the saved d8 we changed is correctly seen by the
> +# inferior.
> +gdb_breakpoint break_here_c temporary
> +gdb_continue_to_breakpoint "continue to break_here_c"
> +gdb_test "p/x value" " = 0x1011121340000000"

Approved-By: Luis Machado <luis.machado@arm.com> (aarch64/arm)
Tested-By: Luis Machado <luis.machado@arm.com> (aarch64/arm)