Re: [PATCH 4/5] gdb/testsuite: Add gdb.arch/aarch64-mops-atomic-inst.exp

[Christophe Lyon <christophe.lyon@linaro.org>]

Hi Thiago,


On Sat, 4 May 2024 at 02:06, Thiago Jung Bauermann
<thiago.bauermann@linaro.org> wrote:
>
> The testcase verifies that MOPS sequences are stepped over when stepping
> the inferior instruction by instruction.
> ---
>  .../gdb.arch/aarch64-mops-atomic-inst.c       | 62 ++++++++++++
>  .../gdb.arch/aarch64-mops-atomic-inst.exp     | 97 +++++++++++++++++++
>  2 files changed, 159 insertions(+)
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.c
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.exp
>
> diff --git a/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.c b/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.c
> new file mode 100644
> index 000000000000..211cfb21c37c
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.c
> @@ -0,0 +1,62 @@
> +/* This file is part of GDB, the GNU debugger.
> +
> +   Copyright 2024 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/>.  */
> +
> +#define TEST_STRING "Just a test string."
> +#define BUF_SIZE sizeof(TEST_STRING)
> +
> +int main(void)
> +{
> +  const char source[BUF_SIZE] = TEST_STRING;
> +  char dest[BUF_SIZE];
> +  char *p = dest;
> +  const char *q;
> +  const long zero = 0;
> +  long size = BUF_SIZE;
> +
> +  /* Break memset.  */
> +  /* memset implemented in MOPS instructions.  */
> +  __asm__ volatile ("setp [%0]!, %1!, %2\n\t"
> +                   "setm [%0]!, %1!, %2\n\t"
> +                   "sete [%0]!, %1!, %2\n\t"
> +                   : "+&r"(p), "+&r"(size)
> +                   : "r"(zero)
> +                   : "memory");
> +
> +  p = dest;
> +  q = source;
> +  /* Break memcpy.  */
> +  /* memcpy implemented in MOPS instructions.  */
> +  __asm__ volatile ("cpyfp   [%0]!, [%1]!, %2!\n\t"
> +                   "cpyfm   [%0]!, [%1]!, %2!\n\t"
> +                   "cpyfe   [%0]!, [%1]!, %2!\n\t"
> +                   : "+&r" (p), "+&r" (q), "+&r" (size)
> +                   :
> +                   : "memory");
> +
> +  p = dest;
> +  q = source;
> +  /* Break memmove.  */
> +  /* memmove implemented in MOPS instructions.  */
> +  __asm__ volatile ("cpyp   [%0]!, [%1]!, %2!\n\t"
> +                   "cpym   [%0]!, [%1]!, %2!\n\t"
> +                   "cpye   [%0]!, [%1]!, %2!\n\t"
> +                   : "+&r" (p), "+&r" (q), "+&r" (size)
> +                   :
> +                   : "memory");
> +
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.exp b/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.exp
> new file mode 100644
> index 000000000000..ad74795d5cfd
> --- /dev/null
> +++ b/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.exp
> @@ -0,0 +1,97 @@
> +# Copyright 2024 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 file is part of the GDB testsuite.
> +
> +# Test single stepping through MOPS (memory operations) atomic sequences.
> +
> +require allow_aarch64_mops_tests
> +
> +standard_testfile
> +if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} \
> +         [list debug additional_flags=-march=armv9.3-a]] } {
> +    return -1
> +}
> +
> +proc is_at_instruction { instruction } {
> +    global gdb_prompt hex
> +
> +    set test "pc points to $instruction"
> +    gdb_test_multiple {x/i $pc} $test {
> +       -re -wrap "=> $hex \[^\r\n\]+:\t$instruction\t\[^\r\n\]+" {
> +           return 1
> +       }
> +       -re "\r\n$gdb_prompt $" {
> +           return 0
> +       }
> +    }
> +
> +    return 0
> +}
> +
> +proc arrive_at_instruction { instruction } {
> +    set count 0
> +
> +    while { [is_at_instruction $instruction] != 1 } {
> +       gdb_test -nopass "nexti" ".*__asm__ volatile.*" \
> +           "nexti #$count to reach $instruction"
> +       incr count
> +
> +       if { $count > 50 } {
> +           fail "didn't reach $instruction"
> +           return 0
> +       }
> +    }
> +
> +    return 1
> +}
> +
> +if ![runto_main] {
> +    return -1
> +}
> +
> +gdb_breakpoint ${srcfile}:[gdb_get_line_number "Break memset"]
> +gdb_breakpoint ${srcfile}:[gdb_get_line_number "Break memcpy"]
> +gdb_breakpoint ${srcfile}:[gdb_get_line_number "Break memmove"]
> +
> +gdb_continue_to_breakpoint "memset breakpoint"
> +
> +if { [arrive_at_instruction setp] } {
> +    # The nexti output isn't useful to detect whether we skipped the sequence.
> +    gdb_test "nexti" "\[^\r\n\]+" "step through the memset sequence"
> +    gdb_assert { [is_at_instruction setm] == 0 \
> +                    && [is_at_instruction sete] == 0 } \
> +       "stepped through the memset sequence"
> +}
> +
> +gdb_continue_to_breakpoint "memcpy breakpoint"
> +
> +if { [arrive_at_instruction cpyfp] } {
> +    # The nexti output isn't useful to detect whether we skipped the sequence.
> +    gdb_test "nexti" "\[^\r\n\]+" "step through the memcpy sequence"
> +    gdb_assert { [is_at_instruction cpyfm] == 0 \
> +                    && [is_at_instruction cpyfe] == 0 } \
> +       "stepped through the memcpy sequence"
> +}
> +
> +gdb_continue_to_breakpoint "memmove breakpoint"
> +
> +if { [arrive_at_instruction cpyp] } {
> +    # The nexti output isn't useful to detect whether we skipped the sequence.
> +    gdb_test "nexti" "\[^\r\n\]+" "step through the memmove sequence"
> +    gdb_assert { [is_at_instruction cpym] == 0 \
> +                    && [is_at_instruction cpye] == 0 } \
> +       "stepped through the memmove sequence"
> +}

I don't know how easy it is nor if it's feasible in the GDB testsuite,
but maybe you could also assert that we stop on the first instruction
after the sequence (so this asm for 'p = dest' and 'return 0'), but I
suspect this would be fragile?

Thanks,

Christophe