watch-read.exp revision 1.7 
1# This testcase is part of GDB, the GNU debugger.
2
3# Copyright 2010-2017 Free Software Foundation, Inc.
4
5# This program is free software; you can redistribute it and/or modify
6# it under the terms of the GNU General Public License as published by
7# the Free Software Foundation; either version 3 of the License, or
8# (at your option) any later version.
9#
10# This program is distributed in the hope that it will be useful,
11# but WITHOUT ANY WARRANTY; without even the implied warranty of
12# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13# GNU General Public License for more details.
14#
15# You should have received a copy of the GNU General Public License
16# along with this program.  If not, see <http://www.gnu.org/licenses/>.
17
18# This file is part of the gdb testsuite.
19
20#
21# Tests involving read watchpoints, and other kinds of watchpoints
22# watching the same memory as read watchpoints.
23#
24
25standard_testfile .c
26
27if {[skip_hw_watchpoint_access_tests]} {
28    return 0
29}
30
31if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
32    return -1
33}
34
35if { ![runto main] } then {
36    fail "run to main"
37    return
38}
39
40set read_line [gdb_get_line_number "read line" $srcfile]
41
42# Test running to a read of `global', with a read watchpoint set
43# watching it.
44
45gdb_test "rwatch global" \
46    "Hardware read watchpoint .*: global" \
47    "set hardware read watchpoint on global variable"
48
49# The first read is on entry to the loop.
50
51gdb_test "continue" \
52    "read watchpoint .*: global.*.*Value = 0.*in main.*$srcfile:$read_line.*" \
53    "read watchpoint triggers on first read"
54
55# The second read happens on second loop iteration, after `global'
56# having been incremented.  On architectures where gdb has to emulate
57# read watchpoints with access watchpoints, this tests the
58# only-report-if-value-changed logic.  On targets that support real
59# read watchpoints, this tests that GDB ignores the watchpoint's old
60# value, knowing that some untrapped write could have changed it, and
61# so reports the read watchpoint unconditionally.
62
63gdb_test "continue" \
64    "read watchpoint .*: global.*.*Value = 1.*in main.*$srcfile:$read_line.*" \
65    "read watchpoint triggers on read after value changed"
66
67# The following tests check that when the user sets a write or access
68# watchpoint watching the same memory as a read watchpoint, GDB also
69# applies the only-report-if-value-changed logic even on targets that
70# support real read watchpoints.
71
72# The program should be stopped at the read line.  Set a write
73# watchpoint (leaving the read watchpoint) and continue.  Only the
74# write watchpoint should be reported as triggering.
75
76gdb_test "watch global" \
77    "atchpoint .*: global" \
78    "set write watchpoint on global variable"
79
80gdb_test "continue" \
81    "atchpoint .*: global.*Old value = 1.*New value = 2.*" \
82    "write watchpoint triggers"
83
84set exp ""
85set exp "${exp}2.*read watchpoint.*keep y.*global.*breakpoint already hit 2 times.*"
86set exp "${exp}3.*watchpoint.*keep y.*global.*breakpoint already hit 1 time.*"
87gdb_test "info watchpoints" \
88    "$exp" \
89    "only write watchpoint triggers when value changes"
90
91# The program is now stopped at the write line.  Continuing should
92# stop at the read line, and only the read watchpoint should be
93# reported as triggering.
94
95gdb_test "continue" \
96    "read watchpoint .*: global.*Value = 2.*in main.*$srcfile:$read_line.*" \
97    "read watchpoint triggers when value doesn't change, trapping reads and writes"
98
99set exp ""
100set exp "${exp}2.*read watchpoint.*keep y.*global.*breakpoint already hit 3 times.*"
101set exp "${exp}3.*watchpoint.*keep y.*global.*breakpoint already hit 1 time.*"
102gdb_test "info watchpoints" \
103    "$exp" \
104    "only read watchpoint triggers when value doesn't change"
105