Fix PR threads/19422 - show which thread caused stop

This commit changes GDB like this:

 - Program received signal SIGINT, Interrupt.
 + Thread 1 "main" received signal SIGINT, Interrupt.

 - Breakpoint 1 at 0x40087a: file threads.c, line 87.
 + Thread 3 "bar" hit Breakpoint 1 at 0x40087a: file threads.c, line 87.

 ... once the program goes multi-threaded.  Until GDB sees a second
thread spawn, the output is still the same as before, per the
discussion back in 2012:

  https://www.sourceware.org/ml/gdb/2012-11/msg00010.html

This helps non-stop mode, where you can't easily tell which thread hit
a breakpoint or received a signal:

 (gdb) info threads
   Id   Target Id         Frame
 * 1    Thread 0x7ffff7fc1740 (LWP 19362) "main" (running)
   2    Thread 0x7ffff7fc0700 (LWP 19366) "foo" (running)
   3    Thread 0x7ffff77bf700 (LWP 19367) "bar" (running)
 (gdb)
 Program received signal SIGUSR1, User defined signal 1.
 0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
 92          lll_wait_tid (pd->tid);
 (gdb) b threads.c:87
 Breakpoint 1 at 0x40087a: file threads.c, line 87.
 (gdb)
 Breakpoint 1, thread_function1 (arg=0x1) at threads.c:87
 87              usleep (1);  /* Loop increment.  */

The best the user can do is run "info threads" and try to figure
things out.

It actually also affects all-stop mode, in case of "handle SIG print
nostop":

...
  Program received signal SIGUSR1, User defined signal 1.

  Program received signal SIGUSR1, User defined signal 1.

  Program received signal SIGUSR1, User defined signal 1.

  Program received signal SIGUSR1, User defined signal 1.
...

The above doesn't give any clue that these were different threads
getting the SIGUSR1 signal.

I initially thought of lowercasing "breakpoint" in

  "Thread 3 hit Breakpoint 1"

but then after trying it I realized that leaving "Breakpoint"
uppercase helps the eye quickly find the relevant information.  It's
also easier to implement not showing anything about threads until the
program goes multi-threaded this way.

Here's a larger example session in non-stop mode:

  (gdb) c -a&
  Continuing.
  (gdb) interrupt -a
  (gdb)
  Thread 1 "main" stopped.
  0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
  92          lll_wait_tid (pd->tid);

  Thread 2 "foo" stopped.
  0x0000003615ebc6ed in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  81      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)

  Thread 3 "bar" stopped.
  0x0000003615ebc6ed in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  81      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
  b threads.c:87
  Breakpoint 4 at 0x40087a: file threads.c, line 87.
  (gdb) b threads.c:67
  Breakpoint 5 at 0x400811: file threads.c, line 67.
  (gdb) c -a&
  Continuing.
  (gdb)
  Thread 3 "bar" hit Breakpoint 4, thread_function1 (arg=0x1) at threads.c:87
  87              usleep (1);  /* Loop increment.  */

  Thread 2 "foo" hit Breakpoint 5, thread_function0 (arg=0x0) at threads.c:68
  68              (*myp) ++;
  info threads
    Id   Target Id         Frame
  * 1  Thread 0x7ffff7fc1740 (LWP 31957) "main" (running)
    2  Thread 0x7ffff7fc0700 (LWP 31961) "foo" thread_function0 (arg=0x0) at threads.c:68
    3  Thread 0x7ffff77bf700 (LWP 31962) "bar" thread_function1 (arg=0x1) at threads.c:87
  (gdb) shell kill -SIGINT 31957
  (gdb)
  Thread 1 "main" received signal SIGINT, Interrupt.
  0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
  92          lll_wait_tid (pd->tid);
  info threads
    Id   Target Id         Frame
  * 1  Thread 0x7ffff7fc1740 (LWP 31957) "main" 0x0000003616a09237 in pthread_join (threadid=140737353877248, thread_return=0x7fffffffd5b8) at pthread_join.c:92
    2  Thread 0x7ffff7fc0700 (LWP 31961) "foo" thread_function0 (arg=0x0) at threads.c:68
    3  Thread 0x7ffff77bf700 (LWP 31962) "bar" thread_function1 (arg=0x1) at threads.c:87
  (gdb) t 2
  [Switching to thread 2, Thread 0x7ffff7fc0700 (LWP 31961)]
  #0  thread_function0 (arg=0x0) at threads.c:68
  68              (*myp) ++;
  (gdb) catch syscall
  Catchpoint 6 (any syscall)
  (gdb) c&
  Continuing.
  (gdb)
  Thread 2 "foo" hit Catchpoint 6 (call to syscall nanosleep), 0x0000003615ebc6ed in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  81      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)

I'll work on documentation next if this looks agreeable.

This patch applies on top of the star wildcards thread IDs series:

  https://sourceware.org/ml/gdb-patches/2016-01/msg00291.html

For convenience, I've pushed this to the
users/palves/show-which-thread-caused-stop branch.

gdb/doc/ChangeLog:
2016-01-18  Pedro Alves  <palves@redhat.com>

	* gdb.texinfo (Threads): Mention that GDB displays the ID and name
	of the thread that hit a breakpoint or received a signal.

gdb/ChangeLog:
2016-01-18  Pedro Alves  <palves@redhat.com>

	* NEWS: Mention that GDB now displays the ID and name of the
	thread that hit a breakpoint or received a signal.
	* break-catch-sig.c (signal_catchpoint_print_it): Use
	maybe_print_thread_hit_breakpoint.
	* break-catch-syscall.c (print_it_catch_syscall): Likewise.
	* break-catch-throw.c (print_it_exception_catchpoint): Likewise.
	* breakpoint.c (maybe_print_thread_hit_breakpoint): New function.
	(print_it_catch_fork, print_it_catch_vfork, print_it_catch_solib)
	(print_it_catch_exec, print_it_ranged_breakpoint)
	(print_it_watchpoint, print_it_masked_watchpoint, bkpt_print_it):
	Use maybe_print_thread_hit_breakpoint.
	* breakpoint.h (maybe_print_thread_hit_breakpoint): Declare.
	* gdbthread.h (show_thread_that_caused_stop): Declare.
	* infrun.c (print_signal_received_reason): Print which thread
	received signal.
	* thread.c (show_thread_that_caused_stop): New function.

gdb/testsuite/ChangeLog:
2016-01-18  Pedro Alves  <palves@redhat.com>

	* gdb.base/async-shell.exp: Adjust expected output.
	* gdb.base/dprintf-non-stop.exp: Adjust expected output.
	* gdb.base/siginfo-thread.exp: Adjust expected output.
	* gdb.base/watchpoint-hw-hit-once.exp: Adjust expected output.
	* gdb.java/jnpe.exp: Adjust expected output.
	* gdb.threads/clone-new-thread-event.exp: Adjust expected output.
	* gdb.threads/continue-pending-status.exp: Adjust expected output.
	* gdb.threads/leader-exit.exp: Adjust expected output.
	* gdb.threads/manythreads.exp: Adjust expected output.
	* gdb.threads/pthreads.exp: Adjust expected output.
	* gdb.threads/schedlock.exp: Adjust expected output.
	* gdb.threads/siginfo-threads.exp: Adjust expected output.
	* gdb.threads/signal-command-multiple-signals-pending.exp: Adjust
	expected output.
	* gdb.threads/signal-delivered-right-thread.exp: Adjust expected
	output.
	* gdb.threads/sigthread.exp: Adjust expected output.
	* gdb.threads/watchpoint-fork.exp: Adjust expected output.

17 files changed, 42 insertions, 21 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 08a699d..627db46 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,24 @@
+2016-01-18  Pedro Alves  <palves@redhat.com>
+
+	* gdb.base/async-shell.exp: Adjust expected output.
+	* gdb.base/dprintf-non-stop.exp: Adjust expected output.
+	* gdb.base/siginfo-thread.exp: Adjust expected output.
+	* gdb.base/watchpoint-hw-hit-once.exp: Adjust expected output.
+	* gdb.java/jnpe.exp: Adjust expected output.
+	* gdb.threads/clone-new-thread-event.exp: Adjust expected output.
+	* gdb.threads/continue-pending-status.exp: Adjust expected output.
+	* gdb.threads/leader-exit.exp: Adjust expected output.
+	* gdb.threads/manythreads.exp: Adjust expected output.
+	* gdb.threads/pthreads.exp: Adjust expected output.
+	* gdb.threads/schedlock.exp: Adjust expected output.
+	* gdb.threads/siginfo-threads.exp: Adjust expected output.
+	* gdb.threads/signal-command-multiple-signals-pending.exp: Adjust
+	expected output.
+	* gdb.threads/signal-delivered-right-thread.exp: Adjust expected
+	output.
+	* gdb.threads/sigthread.exp: Adjust expected output.
+	* gdb.threads/watchpoint-fork.exp: Adjust expected output.
+
 2016-01-18  Yao Qi  <yao.qi@linaro.org>
 
 	* gdb.guile/scm-section-script.c: Replace @progbits with
diff --git a/gdb/testsuite/gdb.base/async-shell.exp b/gdb/testsuite/gdb.base/async-shell.exp
index 5f462b2..6b887c3 100644
--- a/gdb/testsuite/gdb.base/async-shell.exp
+++ b/gdb/testsuite/gdb.base/async-shell.exp
@@ -48,7 +48,7 @@ gdb_test_multiple $test $test {
 
 set test "process stopped"
 gdb_test_multiple "" $test {
-    -re "\r\n\\\[process \[0-9\]+\\\] #1 stopped\\\.\r\n" {
+    -re "Program stopped\\\.\r\n" {
 	pass $test
     }
 }
diff --git a/gdb/testsuite/gdb.base/dprintf-non-stop.exp b/gdb/testsuite/gdb.base/dprintf-non-stop.exp
index 3c1638e..1787f6f 100644
--- a/gdb/testsuite/gdb.base/dprintf-non-stop.exp
+++ b/gdb/testsuite/gdb.base/dprintf-non-stop.exp
@@ -64,7 +64,7 @@ gdb_test_multiple $test $test {
 
 set test "inferior stopped"
 gdb_test_multiple "" $test {
-    -re "\r\n\\\[.*\\\] #1 stopped\\\.\r\n" {
+    -re "Program stopped\\\.\r\n" {
 	pass $test
     }
 }
diff --git a/gdb/testsuite/gdb.base/siginfo-thread.exp b/gdb/testsuite/gdb.base/siginfo-thread.exp
index 49908c4..9af99ea 100644
--- a/gdb/testsuite/gdb.base/siginfo-thread.exp
+++ b/gdb/testsuite/gdb.base/siginfo-thread.exp
@@ -41,7 +41,7 @@ if { ![runto_main] } then {
 }
 
 # Run to the signal.
-gdb_test "continue" ".*Program received signal SIGSEGV.*" "continue to signal"
+gdb_test "continue" "Thread .* received signal SIGSEGV.*" "continue to signal"
 
 # Try to generate a core file, for a later test.
 set gcorefile [standard_output_file $testfile.gcore]
diff --git a/gdb/testsuite/gdb.base/watchpoint-hw-hit-once.exp b/gdb/testsuite/gdb.base/watchpoint-hw-hit-once.exp
index 5c1be00..46d5c62 100644
--- a/gdb/testsuite/gdb.base/watchpoint-hw-hit-once.exp
+++ b/gdb/testsuite/gdb.base/watchpoint-hw-hit-once.exp
@@ -31,7 +31,7 @@ gdb_test "rwatch watchee"
 
 gdb_breakpoint [gdb_get_line_number "dummy = 2"]
 
-gdb_test "continue" "Continuing.\r\nHardware read watchpoint \[0-9\]+: watchee\r\n\r\nValue = 0\r\n.*"
+gdb_test "continue" "Continuing.\r\n\r\nHardware read watchpoint \[0-9\]+: watchee\r\n\r\nValue = 0\r\n.*"
 
 # Here should be no repeated notification of the read watchpoint.
 gdb_test "continue" \
diff --git a/gdb/testsuite/gdb.java/jnpe.exp b/gdb/testsuite/gdb.java/jnpe.exp
index 092d82a..745cdf3 100644
--- a/gdb/testsuite/gdb.java/jnpe.exp
+++ b/gdb/testsuite/gdb.java/jnpe.exp
@@ -51,5 +51,5 @@ gdb_test "next" \
 
 set line [gdb_get_line_number "stop point"]
 gdb_breakpoint $line
-gdb_test "continue" "Continuing.\[\r\n\]*success\[\r\n\]*Breakpoint .*:$line\[\r\n\]*.*// stop point\[\r\n\]*" \
+gdb_test "continue" "Continuing.\[\r\n\]*success\[\r\n\]*Thread .* hit Breakpoint .*:$line\[\r\n\]*.*// stop point\[\r\n\]*" \
   "continue to success for next-over-NPE"
diff --git a/gdb/testsuite/gdb.threads/clone-new-thread-event.exp b/gdb/testsuite/gdb.threads/clone-new-thread-event.exp
index 7b34adc..f7ca41e 100644
--- a/gdb/testsuite/gdb.threads/clone-new-thread-event.exp
+++ b/gdb/testsuite/gdb.threads/clone-new-thread-event.exp
@@ -30,5 +30,5 @@ if { ![runto_main] } {
 }
 
 gdb_test "continue" \
-    "Program received signal SIGUSR1, User defined signal 1.*" \
+    "Thread 2 received signal SIGUSR1, User defined signal 1.*" \
     "catch SIGUSR1"
diff --git a/gdb/testsuite/gdb.threads/continue-pending-status.exp b/gdb/testsuite/gdb.threads/continue-pending-status.exp
index 4d0fce7..086407f 100644
--- a/gdb/testsuite/gdb.threads/continue-pending-status.exp
+++ b/gdb/testsuite/gdb.threads/continue-pending-status.exp
@@ -116,7 +116,7 @@ for {set i 0} {$i < $attempts} {incr i} {
 
 	set msg "caught interrupt"
 	gdb_test_multiple "" $msg {
-	    -re "Program received signal SIGINT.*$gdb_prompt $" {
+	    -re "Thread .* received signal SIGINT.*$gdb_prompt $" {
 		pass $msg
 	    }
 	}
diff --git a/gdb/testsuite/gdb.threads/leader-exit.exp b/gdb/testsuite/gdb.threads/leader-exit.exp
index 2859261..7daea8f 100644
--- a/gdb/testsuite/gdb.threads/leader-exit.exp
+++ b/gdb/testsuite/gdb.threads/leader-exit.exp
@@ -55,7 +55,7 @@ send_gdb "\003"
 
 set test "caught interrupt"
 gdb_test_multiple "" $test {
-    -re "Program received signal SIGINT.*$gdb_prompt $" {
+    -re "Thread .* received signal SIGINT.*$gdb_prompt $" {
 	pass $test
     }
 }
diff --git a/gdb/testsuite/gdb.threads/manythreads.exp b/gdb/testsuite/gdb.threads/manythreads.exp
index 28d3550..8cc4c5c 100644
--- a/gdb/testsuite/gdb.threads/manythreads.exp
+++ b/gdb/testsuite/gdb.threads/manythreads.exp
@@ -70,14 +70,14 @@ proc interrupt_and_wait { message } {
 	-re "\\\[\[^\]\]* exited\\\]\r\n" {
 	    exp_continue
 	}
-	-re "Program received signal SIGINT.*$gdb_prompt $" {
+	-re " received signal SIGINT.*$gdb_prompt $" {
 	    pass "$message"
 	}
 	-re "$gdb_prompt $" {
 	    # Note that with this regex order, if GDB emits [New
 	    # Thread ...] output between "Program received signal" and
-	    # the prompt, the "Program received signal" regex won't
-	    # match.  That's good, as if we see that happening, it's a
+	    # the prompt, the "received signal" regex won't match.
+	    # That's good, as if we see that happening, it's a
 	    # regression.
 	    #
 	    # GDB makes sure to notify about signal stops, end of
@@ -92,7 +92,7 @@ proc interrupt_and_wait { message } {
 	    #  ... more new threads output ...
 	    #  [New Thread NNN]
 	    #  [New Thread NNN]
-	    #  Program received signal SIGINT, Interrupt.
+	    #  Thread NNN received signal SIGINT, Interrupt.
 	    #  [New Thread NNN]
 	    #  [New Thread NNN]
 	    #  ... pages of new threads output ...
diff --git a/gdb/testsuite/gdb.threads/pthreads.exp b/gdb/testsuite/gdb.threads/pthreads.exp
index 473053e..1fb27cf 100644
--- a/gdb/testsuite/gdb.threads/pthreads.exp
+++ b/gdb/testsuite/gdb.threads/pthreads.exp
@@ -202,7 +202,7 @@ proc check_control_c {} {
     send_gdb "\003"
     set description "Stopped with a ^C"
     gdb_expect {
-	-re "Program received signal SIGINT.*$gdb_prompt $" {
+	-re "Thread .* received signal SIGINT.*$gdb_prompt $" {
 	    pass $description
 	}
 	-re "Quit.*$gdb_prompt $" {
diff --git a/gdb/testsuite/gdb.threads/schedlock.exp b/gdb/testsuite/gdb.threads/schedlock.exp
index 8232697..6fb6698 100644
--- a/gdb/testsuite/gdb.threads/schedlock.exp
+++ b/gdb/testsuite/gdb.threads/schedlock.exp
@@ -69,7 +69,7 @@ proc stop_process { description } {
   # message first, or GDB's signal handler may not be in place.
   after 1000 {send_gdb "\003"}
   gdb_expect {
-    -re "Program received signal SIGINT.*$gdb_prompt $"
+    -re "Thread .* received signal SIGINT.*$gdb_prompt $"
       {
 	pass $description
       }
diff --git a/gdb/testsuite/gdb.threads/siginfo-threads.exp b/gdb/testsuite/gdb.threads/siginfo-threads.exp
index 9c55b74..108d240 100644
--- a/gdb/testsuite/gdb.threads/siginfo-threads.exp
+++ b/gdb/testsuite/gdb.threads/siginfo-threads.exp
@@ -51,7 +51,7 @@ for {set sigcount 0} {$sigcount < 4} {incr sigcount} {
     set test "catch signal $sigcount"
     set sigusr ""
     gdb_test_multiple "continue" $test {
-	-re "Program received signal SIGUSR(\[12\]), User defined signal \[12\]\\.\r\n.*\r\n$gdb_prompt $" {
+	-re "Thread .* received signal SIGUSR(\[12\]), User defined signal \[12\]\\.\r\n.*\r\n$gdb_prompt $" {
 	    set sigusr $expect_out(1,string)
 	    pass $test
 	}
diff --git a/gdb/testsuite/gdb.threads/signal-command-multiple-signals-pending.exp b/gdb/testsuite/gdb.threads/signal-command-multiple-signals-pending.exp
index 450e472..43fe779 100644
--- a/gdb/testsuite/gdb.threads/signal-command-multiple-signals-pending.exp
+++ b/gdb/testsuite/gdb.threads/signal-command-multiple-signals-pending.exp
@@ -68,9 +68,9 @@ proc test { schedlock } {
 	# signal.
 
 	gdb_test "thread 3" "Switching to thread 3.*"
-	gdb_test "continue" "Program received signal SIGUSR2.*" "stop with SIGUSR2"
+	gdb_test "continue" "Thread 3 .*received signal SIGUSR2.*" "stop with SIGUSR2"
 	gdb_test "thread 2" "Switching to thread 2.*"
-	gdb_test "continue" "Program received signal SIGUSR1.*" "stop with SIGUSR1"
+	gdb_test "continue" "Thread 2 .*received signal SIGUSR1.*" "stop with SIGUSR1"
 
 	gdb_test "break handler_sigusr1" "Breakpoint .* at .*$srcfile.*"
 	gdb_test "break handler_sigusr2" "Breakpoint .* at .*$srcfile.*"
diff --git a/gdb/testsuite/gdb.threads/signal-delivered-right-thread.exp b/gdb/testsuite/gdb.threads/signal-delivered-right-thread.exp
index d3ce821..b7ce8ef 100644
--- a/gdb/testsuite/gdb.threads/signal-delivered-right-thread.exp
+++ b/gdb/testsuite/gdb.threads/signal-delivered-right-thread.exp
@@ -41,7 +41,7 @@ proc test { command } {
 
 	gdb_test "handle SIGUSR1 stop print pass"
 
-	gdb_test "continue" "Program received signal SIGUSR1.*" "stop with SIGUSR1"
+	gdb_test "continue" "Thread 2 .*received signal SIGUSR1.*" "stop with SIGUSR1"
 
 	set pattern "\\\* 2\[ \t\]+Thread.*"
 
diff --git a/gdb/testsuite/gdb.threads/sigthread.exp b/gdb/testsuite/gdb.threads/sigthread.exp
index bf7fa9b..71ef75a 100644
--- a/gdb/testsuite/gdb.threads/sigthread.exp
+++ b/gdb/testsuite/gdb.threads/sigthread.exp
@@ -49,4 +49,4 @@ after 500 {send_gdb "\003"}
 
 # Make sure we do not get an internal error from hitting Control-C
 # while many signals are flying back and forth.
-gdb_test "" "Program received signal SIGINT.*" "stop with control-c"
+gdb_test "" "Thread .* received signal SIGINT.*" "stop with control-c"
diff --git a/gdb/testsuite/gdb.threads/watchpoint-fork.exp b/gdb/testsuite/gdb.threads/watchpoint-fork.exp
index a833c98..1682982 100644
--- a/gdb/testsuite/gdb.threads/watchpoint-fork.exp
+++ b/gdb/testsuite/gdb.threads/watchpoint-fork.exp
@@ -75,7 +75,7 @@ proc test {type symbol} {
 		"reakpoint \[0-9\]+, marker.*" "breakpoint after the second fork"
 	    gdb_test "continue" \
 		"atchpoint \[0-9\]+: var.*Old value = 2.*New value = 3.*mark_exit \\(\\);" "watchpoint after the second fork"
-	    gdb_test "continue" "Continuing\\..*\r\nBreakpoint \[0-9\]+, mark_exit .*" "finish"
+	    gdb_test "continue" "Continuing\\..*\r\n(Thread .* hit )?Breakpoint \[0-9\]+, mark_exit .*" "finish"
 	}
 
 	# threads
@@ -129,7 +129,7 @@ proc test {type symbol} {
 		"atchpoint \[0-9\]+: var.*Old value = 5.*New value = 6.*after-fork2-A.*" "watchpoint A after the second fork"
 	    gdb_test "continue" \
 		"atchpoint \[0-9\]+: var.*Old value = 6.*New value = 7.*after-fork2-B.*" "watchpoint B after the second fork"
-	    gdb_test "continue" "Continuing\\..*\r\nBreakpoint \[0-9\]+, mark_exit .*" "finish"
+	    gdb_test "continue" "Continuing\\..*\r\nThread .* hit Breakpoint \[0-9\]+, mark_exit .*" "finish"
 	}
     }
 }