gdb/testsuite/gdb.threads/step-bg-decr-pc-switch-thread.exp

# Copyright (C) 2014-2025 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/>.

# On decr_pc_after_break targets, GDB used to adjust the PC
# incorrectly if a background single-step stopped somewhere where
# PC-$decr_pc had a breakpoint, and the thread was not the current
# thread, like:
#
#   ADDR1 nop <-- breakpoint here
#   ADDR2 jmp PC
#
#  IOW, say thread A is stepping ADDR2's line in the background (an
#  infinite loop), and the user switches focus to thread B.  GDB's
#  adjust_pc_after_break logic would confuse the single-step stop of
#  thread A for a hit of the breakpoint at ADDR1, and thus adjust
#  thread A's PC to point at ADDR1 when it should not: the thread had
#  been single-stepped, not continued.

standard_testfile

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

if ![runto_main] {
    return
}

# Make sure it's GDB's decr_pc logic that's being tested, not the
# target's.
gdb_test_no_output "set range-stepping off"

delete_breakpoints

gdb_breakpoint [gdb_get_line_number "set breakpoint here"]
gdb_continue_to_breakpoint "run to nop breakpoint"
gdb_test "info threads" "  1 .*\\\* 2 .*" "info threads shows all threads"

gdb_test "next" "while.*" "next over nop"

gdb_test_no_output "next&" "next& over inf loop"

set test "switch to main thread"
gdb_test_multiple "thread 1" $test {
    -re "Cannot execute this command while the target is running.*$gdb_prompt $" {
	
	# With remote targets, we can't send any other remote packet
	# until the target stops.  Switching thread wants to ask the
	# remote side whether the thread is alive.
	unsupported $gdb_test_name

	# Interrupt running target to allow subsequent "monitor exit" to
	# succeed.
	gdb_test_multiple interrupt "" {
	    -re -wrap "" {
		exp_continue
	    }
	    -re "received signal SIGINT, Interrupt\\.\r\n.*" {
		pass $gdb_test_name
	    }
	}
	return
    }
    -re "Switching to thread 1.*\\(running\\)\r\n$gdb_prompt " {
	# Prefer to match the prompt without an anchor.  If there's a
	# bug and output comes after the prompt immediately, it's
	# faster to handle that in the following test, instead of
	# waiting for a timeout here.
	pass $test
    }
}

# Wait a bit.  Use gdb_expect instead of sleep so that any (bad) GDB
# output is visible in the log.
gdb_expect 4 {}

set test "no output while stepping"
gdb_test_multiple "" $test {
    -timeout 1
    timeout {
	pass $test
    }
    -re "." {
	# If we see any output, it's a failure.  On the original bug,
	# this would be a breakpoint hit.
	fail $test
    }
}