record: set stop_pc in "record goto" command

When navigating in the recorded execution trace via "record goto", we do not
set stop_pc.  This may trigger an internal error in infrun.c when stepping
from that location.  Set it.

(gdb) rec full
(gdb) c
Continuing.

Breakpoint 1, foo (void) at foo.c:42
42             x = y
(gdb) rn
foo (void)
    at foo.c:41
41             y = x
(gdb) rec go end
Go forward to insn number 98724
    at foo.c:42
42             x = y
(gdb) n
infrun.c:2382: internal-error: resume: Assertion `sig != GDB_SIGNAL_0' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)

This happens because there's a breakpoint at PC when the "next"
is issued, so that breapoint should be immediately stepped over.
That should have been detected/done by proceed, here:

  if (addr == (CORE_ADDR) -1)
    {
      if (pc == stop_pc
	  && breakpoint_here_p (aspace, pc) == ordinary_breakpoint_here
	  && execution_direction != EXEC_REVERSE)
	/* There is a breakpoint at the address we will resume at,
	   step one instruction before inserting breakpoints so that
	   we do not stop right away (and report a second hit at this
	   breakpoint).

	   Note, we don't do this in reverse, because we won't
	   actually be executing the breakpoint insn anyway.
	   We'll be (un-)executing the previous instruction.  */
	tp->stepping_over_breakpoint = 1;

But since stop_pc was stale, the pc == stop_pc check failed, and left the
breakpont at PC inserted.

gdb/
	* record-btrace.c (record_btrace_goto_begin, record_btrace_goto_end)
	record_btrace_goto): Move call to print_stack_frame ...
	(record_btrace_set_replay): ... here.  Set stop_pc.
	* record-full.c (record_full_goto_entry): Set stop_pc.

testsuite/
	* gdb.btrace/record_goto-step.exp: New.

5 files changed, 63 insertions, 6 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 268efb0..5683482 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2015-07-10  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* record-btrace.c (record_btrace_goto_begin)
+	(record_btrace_goto_end, record_btrace_goto): Move call to
+	print_stack_frame ...
+	(record_btrace_set_replay): ... here.  Set stop_pc.
+	* record-full.c (record_full_goto_entry): Set stop_pc.
+
 2015-07-09  Pierre Langlois  <pierre.langlois@arm.com>
 
 	* NEWS: Mention support for tracepoints on aarch64-linux.
diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 969e01b..6f4ee66 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -2212,6 +2212,9 @@ record_btrace_set_replay (struct thread_info *tp,
 
   /* Start anew from the new replay position.  */
   record_btrace_clear_histories (btinfo);
+
+  stop_pc = regcache_read_pc (get_current_regcache ());
+  print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1);
 }
 
 /* The to_goto_record_begin method of target record-btrace.  */
@@ -2226,8 +2229,6 @@ record_btrace_goto_begin (struct target_ops *self)
 
   btrace_insn_begin (&begin, &tp->btrace);
   record_btrace_set_replay (tp, &begin);
-
-  print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1);
 }
 
 /* The to_goto_record_end method of target record-btrace.  */
@@ -2240,8 +2241,6 @@ record_btrace_goto_end (struct target_ops *ops)
   tp = require_btrace_thread ();
 
   record_btrace_set_replay (tp, NULL);
-
-  print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1);
 }
 
 /* The to_goto_record method of target record-btrace.  */
@@ -2267,8 +2266,6 @@ record_btrace_goto (struct target_ops *self, ULONGEST insn)
     error (_("No such instruction."));
 
   record_btrace_set_replay (tp, &it);
-
-  print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1);
 }
 
 /* The to_execution_direction target method.  */
diff --git a/gdb/record-full.c b/gdb/record-full.c
index 43e8be2..1520811 100644
--- a/gdb/record-full.c
+++ b/gdb/record-full.c
@@ -1869,6 +1869,7 @@ record_full_goto_entry (struct record_full_entry *p)
 
   registers_changed ();
   reinit_frame_cache ();
+  stop_pc = regcache_read_pc (get_current_regcache ());
   print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1);
 }
 
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index fe6fddc..043f2a1 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2015-07-10  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* gdb.btrace/record_goto-step.exp: New.
+
 2015-07-08  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	PR compile/18484
diff --git a/gdb/testsuite/gdb.btrace/record_goto-step.exp b/gdb/testsuite/gdb.btrace/record_goto-step.exp
new file mode 100644
index 0000000..90347e9
--- /dev/null
+++ b/gdb/testsuite/gdb.btrace/record_goto-step.exp
@@ -0,0 +1,47 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2013-2015 Free Software Foundation, Inc.
+#
+# Contributed by Intel Corp. <markus.t.metzger@intel.com>
+#
+# 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/>.
+
+# check for btrace support
+if { [skip_btrace_tests] } { return -1 }
+
+standard_testfile record_goto.c
+
+# start inferior
+if [prepare_for_testing record_goto-step.exp $testfile $srcfile] {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+set bp [gdb_get_line_number "fun4.3" $srcfile]
+gdb_breakpoint $srcfile:$bp
+
+# record the execution until we hit a breakpoint
+gdb_test_no_output "record btrace"
+gdb_continue_to_breakpoint "cont to $bp" ".*fun4\.3.*"
+
+# reverse-step, then jump to the end of the trace
+gdb_test "reverse-next" ".*fun4\.2.*"
+gdb_test "record goto end" ".*fun4\.3.*"
+
+# test that we can step away from a breakpoint after jumping to
+# the breakpoint PC
+gdb_test "next" ".*fun4\.4.*"