gdb/testsuite/gdb.trace/circ.exp

# Copyright 1998-2021 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/>.

load_lib "trace-support.exp"

standard_testfile

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

# Tests:
# 1) Calculate the size taken by one trace frame.
# 2) Set up a trace experiment that will collect approximately 10 frames,
#    requiring more than 512 but less than 1024 bytes of cache buffer.
#    (most targets should have at least 1024 bytes of cache buffer!)
#    Run and confirm that it collects all 10 frames.
# 3) Artificially limit the trace buffer to 4x + a bytes.  Here x is the size
#    of single trace frame and a is a small constant.  Rerun the
#    experiment.  Confirm that the frame for the first tracepoint is collected,
#    but frames for the last several tracepoints are not.
# 4) Set trace buffer to circular mode, with the buffer size as in
#    step 3 above.  Rerun the experiment.  Confirm that the frame for the last
#    tracepoint is collected but not for the first one.
#

# Set a tracepoint on given func.  The tracepoint is set at entry
# address and not 'after prologue' address because we use 
# 'tfind pc func' to find the corresponding trace frame afterwards,
# and that looks for entry address.
proc set_a_tracepoint { func } {
    gdb_test "trace \*$func" "Tracepoint \[0-9\]+ at .*" \
	"set tracepoint at $func"
    gdb_trace_setactions "set actions for $func" "" "collect testload" "^$"
}

# Sets the tracepoints from func0 to func9 using set_a_tracepoint.
proc setup_tracepoints { } {
    gdb_delete_tracepoints
    set_a_tracepoint func0
    set_a_tracepoint func1
    set_a_tracepoint func2
    set_a_tracepoint func3
    set_a_tracepoint func4
    set_a_tracepoint func5
    set_a_tracepoint func6
    set_a_tracepoint func7
    set_a_tracepoint func8
    set_a_tracepoint func9
}

# Start the trace, run to end and then stop the trace.
proc run_trace_experiment { } {
    global decimal

    setup_tracepoints
    gdb_breakpoint "end" qualified
    gdb_test "tstart" "\[\r\n\]*" "start trace experiment"
    gdb_test "continue" "Continuing.*Breakpoint \[0-9\]+, end.*" \
	"run to end"
    gdb_test "tstop" "\[\r\n\]*" "stop trace experiment"
}

if { ![runto_main] } {
    return -1
}

if { ![gdb_target_supports_trace] } {
    unsupported "target does not support trace"
    return 1
}

set test "set circular-trace-buffer on"
gdb_test_multiple "set circular-trace-buffer on" $test {
    -re ".*Target does not support this command.*$gdb_prompt $" {
	unsupported "target does not support circular trace buffer"
	return 1
    }
    -re "$gdb_prompt $" {
	pass $test
    }
}

set circular_supported -1
set test "check whether circular buffer is supported"

gdb_test_multiple "tstatus" $test {
    -re ".*Trace buffer is circular.*$gdb_prompt $" {
	set circular_supported 1
	pass $test
    }
    -re "$gdb_prompt $" {
	pass $test
    }
}

if { $circular_supported < 0 } {
    unsupported "target does not support circular trace buffer"
    return 1
}

gdb_test "show circular-trace-buffer" \
    "Target's use of circular trace buffer is on." \
    "show circular-trace-buffer (on)"

# Check if changing the trace buffer size is supported.  This step is
# repeated twice.  This helps in case the trace buffer size is 100.
set test_size 100
set test "change buffer size to $test_size"
gdb_test_multiple "set trace-buffer-size $test_size" $test {
    -re ".*Target does not support this command.*$gdb_prompt $" {
	unsupported "target does not support changing trace buffer size"
	return 1
    }
    -re "$gdb_prompt $" {
	pass $test
    }
}

set test "check whether setting trace buffer size is supported"
gdb_test_multiple "tstatus" $test {
    -re ".*Trace buffer has ($decimal) bytes of ($decimal) bytes free.*$gdb_prompt $" {
	set total_size $expect_out(2,string)
	if { $test_size != $total_size } {
	    unsupported "target does not support changing trace buffer size"
	    return 1
	}
	pass $test
    }
}

set test_size 400
gdb_test_no_output "set trace-buffer-size $test_size" \
    "change buffer size to $test_size"

gdb_test_multiple "tstatus" $test {
    -re ".*Trace buffer has ($decimal) bytes of ($decimal) bytes free.*$gdb_prompt $" {
	set total_size $expect_out(2,string)
	if { $test_size != $total_size } {
	    unsupported "target does not support changing trace buffer size"
	    return 1
	}
	pass $test
    }
}

gdb_test_no_output "set circular-trace-buffer off" \
    "set circular-trace-buffer off"

gdb_test "show circular-trace-buffer" \
    "Target's use of circular trace buffer is off." \
    "show circular-trace-buffer (off)"

set total_size -1
set free_size -1
set frame_size -1

# Determine the size used by a single frame.  Set a single tracepoint,
# run and then check the total and free size using the tstatus command.
# Then subtracting free from total gives us the size of a frame.
with_test_prefix "frame size" {
    set_a_tracepoint func0

    gdb_breakpoint "end" qualified

    gdb_test "tstart" "\[\r\n\]*" "start trace"

    gdb_test "continue" "Continuing.*Breakpoint \[0-9\]+, end.*" \
	"run to end"

    gdb_test "tstop" "\[\r\n\]*" "stop trace"

    set test "get buffer size"

    gdb_test_multiple "tstatus" $test {
	-re ".*Trace buffer has ($decimal) bytes of ($decimal) bytes free.*$gdb_prompt $" {
	    set free_size $expect_out(1,string)
	    set total_size $expect_out(2,string)
	    pass $test
	}
    }

    # Check that we get the total_size and free_size.
    if { $total_size < 0 } {
	return 1
    }

    if { $free_size < 0 } {
	return 1
    }
}

# Calculate the size of a single frame.
set frame_size "($total_size - $free_size)"

with_test_prefix "normal buffer" {
    clean_restart $testfile

    if { ![runto_main] } {
	return 1
    }

    run_trace_experiment

    # Check that the first frame is actually at func0.
    gdb_test "tfind start" ".*#0  func0 .*" \
	"first frame is at func0"

    gdb_test "tfind pc func9" \
	".*Found trace frame $decimal, tracepoint $decimal\r\n#0  func9 .*" \
	"find frame for func9"
}

# Shrink the trace buffer so that it will not hold
# all ten trace frames.  Verify that the frame for func0 is still
# collected, but the frame for func9 is not.

set buffer_size "((4 * $frame_size) + 10)"
with_test_prefix "small buffer" {
    clean_restart $testfile

    if { ![runto_main] } {
	return 1
    }

    gdb_test_no_output "set trace-buffer-size $buffer_size" \
	"shrink the target trace buffer"

    run_trace_experiment

    gdb_test "tfind start" ".*#0  func0 .*" \
	"first frame is at func0"

    gdb_test "tfind pc func9" ".* failed to find .*" \
	"find frame for func9"
}

# Finally, make the buffer circular.  Now when it runs out of
# space, it should wrap around and overwrite the earliest frames.
# This means that:
# 1) the first frame will be overwritten and therefore unavailable.
# 2) the earliest frame in the buffer will not be for func0.
# 3) the frame for func9 will be available (unlike "small buffer" case).
with_test_prefix "circular buffer" {
    clean_restart $testfile

    if { ![runto_main] } {
	return 1
    }

    gdb_test_no_output "set trace-buffer-size $buffer_size" \
	"shrink the target trace buffer"

    gdb_test_no_output "set circular-trace-buffer on" \
	"make the target trace buffer circular"

    run_trace_experiment

    gdb_test "tstatus" \
	".*Buffer contains $decimal trace frames \\(of $decimal created total\\).*Trace buffer is circular.*" \
	"trace buffer is circular"

    # The first frame should not be at func0.
    gdb_test "tfind start" ".*#0  func\[1-9\] .*" \
	"first frame is NOT at func0"

    gdb_test \
	"tfind pc func9" \
	".*Found trace frame $decimal, tracepoint $decimal\r\n#0  func9 .*" \
	"find frame for func9"
}