gdb/testsuite/gdb.arch/amd64-watchpoint-downgrade.exp

# Copyright 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/>.

# Ask GDB to watch a large structure before the inferior has started,
# GDB will assume it can place a hardware watchpoint.
#
# Once the inferior starts GDB realises that it is not able to watch
# such a large structure and downgrades to a software watchpoint.
#
# This test checks that GDB emits a warnings about this downgrade, as
# a software watchpoint will be significantly slower than a hardware
# watchpoint, and the user probably wants to know about this.

require target_can_use_run_cmd is_x86_64_m64_target

# The remote/extended-remote target has its own set of flags to
# control the use of s/w vs h/w watchpoints, this test isn't about
# those, so skip the test in these cases.
if {[target_info gdb_protocol] == "remote"
    || [target_info gdb_protocol] == "extended-remote"} {
    unsupported "using [target_info gdb_protocol] protocol"
    return -1
}

standard_testfile

if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} \
	  { debug }] } {
    return -1
}

# Insert the watchpoint, it should default to a h/w watchpoint.
gdb_test "watch global_var" \
    "Hardware watchpoint $decimal: global_var"
set num [get_integer_valueof "\$bpnum" "*UNKNOWN*" \
	     "get watchpoint number"]

# Watchpoint should initially show as a h/w watchpoint.
gdb_test "info watchpoints" \
    "\r\n$num\\s+hw watchpoint\\s+keep\\s+y\\s+global_var" \
    "check info watchpoints before starting"

# Start the inferior, GDB should emit a warning that the watchpoint
# type has changed.
gdb_test "starti" \
    [multi_line \
	 "warning: watchpoint $num downgraded to software watchpoint" \
	 "" \
	 "Program stopped\\." \
	 ".*"]

# Watchpoint should now have downgraded to a s/w watchpoint.
gdb_test "info watchpoints" \
    "\r\n$num\\s+watchpoint\\s+keep\\s+y\\s+global_var" \
    "check info watchpoints after starting"