From e242fd1249ae85a97f08f95d5c61f4cbe3b906e0 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Tue, 9 Apr 2019 12:32:26 -0400 Subject: [PATCH] Use -qualified flag when setting temporary breakpoint in start command When using the "start" command, GDB puts a temporary breakpoint on the "main" symbol (we literally invoke the tbreak command). However, since it does wild matching by default, it also puts a breakpoint on any C++ method or "main" function in a namespace. For example, when debugging GDB, it creates a total of 24 locations: (gdb) start Temporary breakpoint 1 at 0x198c1e9: main. (24 locations) as there are a bunch of methods called main in the selftests, such as selftests::string_view::capacity_1::main() If such method was called in the constructor of a global object, or a function marked with the attribute "constructor", then we would stop at the wrong place. Also, this causes a few extra symtabs (those that contain the "wrong" mains) to be expanded for nothing. The dummiest, most straightforward solution is to add -qualified when invoking tbreak. With this patch, "start" creates a single-location breakpoint, as expected. I copied the start.exp test to start-cpp.exp and made it use a C++ test file, which contains two main functions. The new test verifies that the output of "start" is the output we get when we set a single-location breakpoint. gdb/ChangeLog: * infcmd.c (run_command_1): Pass -qualified to tbreak when usind the "start" command. gdb/testsuite/ChangeLog: * gdb.base/start-cpp.exp: New file. * gdb.base/start-cpp.cc: New file. --- gdb/ChangeLog | 5 +++++ gdb/infcmd.c | 5 ++++- gdb/testsuite/ChangeLog | 5 +++++ gdb/testsuite/gdb.base/start-cpp.cc | 33 ++++++++++++++++++++++++++++++++ gdb/testsuite/gdb.base/start-cpp.exp | 37 ++++++++++++++++++++++++++++++++++++ 5 files changed, 84 insertions(+), 1 deletion(-) create mode 100644 gdb/testsuite/gdb.base/start-cpp.cc create mode 100644 gdb/testsuite/gdb.base/start-cpp.exp diff --git a/gdb/ChangeLog b/gdb/ChangeLog index e1d20fd..7af9b90 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2019-04-09 Simon Marchi + + * infcmd.c (run_command_1): Pass -qualified to tbreak when usind + the "start" command. + 2019-04-08 Kevin Buettner * python/py-inferior.c (infpy_thread_from_thread_handle): diff --git a/gdb/infcmd.c b/gdb/infcmd.c index 3b26fd4..178f89e 100644 --- a/gdb/infcmd.c +++ b/gdb/infcmd.c @@ -604,7 +604,10 @@ run_command_1 (const char *args, int from_tty, enum run_how run_how) /* Insert temporary breakpoint in main function if requested. */ if (run_how == RUN_STOP_AT_MAIN) - tbreak_command (main_name (), 0); + { + std::string arg = string_printf ("-qualified %s", main_name ()); + tbreak_command (arg.c_str (), 0); + } exec_file = get_exec_file (0); diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 5f1ce3c..5c7cadf 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2019-04-09 Simon Marchi + + * gdb.base/start-cpp.exp: New file. + * gdb.base/start-cpp.cc: New file. + 2019-04-08 Kevin Buettner * gdb.python/py-thrhandle.exp: Adjust tests to call diff --git a/gdb/testsuite/gdb.base/start-cpp.cc b/gdb/testsuite/gdb.base/start-cpp.cc new file mode 100644 index 0000000..1d0fd7d --- /dev/null +++ b/gdb/testsuite/gdb.base/start-cpp.cc @@ -0,0 +1,33 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2019 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 . */ + +namespace foo +{ + +int +main () +{ + return 1; +} + +} /* namespace foo */ + +int +main () +{ + return foo::main (); +} diff --git a/gdb/testsuite/gdb.base/start-cpp.exp b/gdb/testsuite/gdb.base/start-cpp.exp new file mode 100644 index 0000000..5f98b92 --- /dev/null +++ b/gdb/testsuite/gdb.base/start-cpp.exp @@ -0,0 +1,37 @@ +# Copyright 2005-2019 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 . + +standard_testfile .cc + +if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} { + return -1 +} + +# This is a testcase specifically for the `start' GDB command. For regular +# stop-in-main goal in the testcases consider using `runto_main' instead. + +# In this C++ version of the test (as opposed to start.exp), we specifically +# test that the temporary breakpoint created by the start command has a single +# location, even if we have a function named "main" in a non-root namespace. + +# For C++ programs, "start" should stop in main(). +if { [gdb_start_cmd] < 0 } { + untested start + return -1 +} + +gdb_test "" \ + "Temporary breakpoint $decimal at $hex: file.*main \\(\\) at .*start-cpp.cc:.*" \ + "start" -- 2.7.4