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Pedro Alves f303dbd60d 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.
2016-01-18 15:15:18 +00:00
bfd Automatic date update in version.in 2016-01-18 00:00:08 +00:00
binutils Provide AC_PROG_LEX that copes with LEX=missing from top-level 2016-01-18 22:17:57 +10:30
config Provide AC_PROG_LEX that copes with LEX=missing from top-level 2016-01-18 22:17:57 +10:30
cpu Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
elfcpp Remove typename from Mips64_rela_data 2016-01-12 12:08:06 -08:00
etc
gas Provide AC_PROG_LEX that copes with LEX=missing from top-level 2016-01-18 22:17:57 +10:30
gdb Fix PR threads/19422 - show which thread caused stop 2016-01-18 15:15:18 +00:00
gold [gold][aarch64] PR gold/19472 - DSOs need pc-relative stubs. 2016-01-15 17:10:04 -08:00
gprof Regen configure 2016-01-17 12:28:14 +10:30
include Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
intl Regen intl/configure 2015-08-31 12:53:36 +09:30
ld Re-enable rgn-at11 test for MIPS targets with adjusted section alignment. 2016-01-18 13:00:33 +00:00
libdecnumber Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
libiberty libiberty: {count,dup,write}argv: constify argv input slightly 2016-01-05 15:25:13 -05:00
opcodes Regen configure 2016-01-17 12:28:14 +10:30
readline Revert "Sync readline/ to version 7.0 alpha" 2015-07-25 15:57:00 -04:00
sim Minor comment fixes in sim/common/sim-fpu.c. 2016-01-17 09:34:29 +04:00
texinfo
zlib Import zlib 1.2.8 with local change merged in. 2015-11-25 15:14:47 -08:00
.cvsignore
.gitattributes
.gitignore Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
COPYING
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
COPYING3
COPYING3.LIB
ChangeLog Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
MAINTAINERS
Makefile.def Sync top-level Makefile.def with GCC 2016-01-12 08:34:40 -08:00
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compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
config.guess Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
config.rpath
config.sub Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
configure Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
configure.ac Import changes made to files shared with the FSF GCC project. 2016-01-11 11:06:56 +00:00
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4 Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
ltgcc.m4
ltmain.sh
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mkdep
mkinstalldirs Update from upstream Automake 2014-11-16 13:43:48 +01:00
move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
setup.com
src-release.sh fix gdb version parsing in src-release.sh 2016-01-17 10:01:55 +04:00
symlink-tree
ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

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