Add gdb.arch/aarch64-mops-atomic-inst.exp

The testcase verifies the stepping instruction by instruction, and was
verified to trigger FAILs if the corresponding code in GDB is removed:

  Running /home/bauermann/src/binutils-gdb/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.exp ...
  PASS: gdb.arch/aarch64-mops-atomic-inst.exp: continue to breakpoint: memset breakpoint
  PASS: gdb.arch/aarch64-mops-atomic-inst.exp: step through the memset sequence
  FAIL: gdb.arch/aarch64-mops-atomic-inst.exp: stepped through the memset sequence
  PASS: gdb.arch/aarch64-mops-atomic-inst.exp: continue to breakpoint: memcpy breakpoint
  PASS: gdb.arch/aarch64-mops-atomic-inst.exp: step through the memcpy sequence
  FAIL: gdb.arch/aarch64-mops-atomic-inst.exp: stepped through the memcpy sequence
  PASS: gdb.arch/aarch64-mops-atomic-inst.exp: continue to breakpoint: memmove breakpoint
  PASS: gdb.arch/aarch64-mops-atomic-inst.exp: step through the memmove sequence
  FAIL: gdb.arch/aarch64-mops-atomic-inst.exp: stepped through the memmove sequence

		=== gdb Summary ===

  # of expected passes		6
  # of unexpected failures	3

2 files changed, 147 insertions, 0 deletions

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 00000000000..211cfb21c37
--- /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 00000000000..e31683314fa
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-mops-atomic-inst.exp
@@ -0,0 +1,85 @@
+# 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
+    }
+}
+
+runto_main
+
+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"
+
+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"
+
+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"
+
+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"