reverse-finish: turn internal error into normal error

The reverse-finish command results in an internal error if it cannot determine
the current function.

  (gdb) c
  Continuing.

  Program received signal SIGSEGV, Segmentation fault.
  0x0000000000000000 in ?? ()
  (gdb) reverse-finish
  Run back to call of #0  0x0000000000000000 in ?? ()
  gdb/infcmd.c:1576: internal-error: Finish: couldn't find function.
  A problem internal to GDB has been detected,
  further debugging may prove unreliable.
  Quit this debugging session? (y or n) y

This is not an internal error case since the command may be used in scenarios
where there is no function at the current PC, e.g. after calling through a bad
function pointer.

Turn this into a normal error.

gdb/
	* infcmd.c (finish_backward): Turn internal error into normal error.

testsuite/
	* gdb.btrace/segv.c: New.
	* gdb.btrace/segv.exp: New.

gdb/ChangeLog

@@ -1,3 +1,7 @@
+2014-07-08  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* infcmd.c (finish_backward): Turn internal error into normal error.
+
 2014-07-07  Pedro Alves  <palves@redhat.com>
 
 	PR gdb/17096

gdb/infcmd.c

@@ -1573,8 +1573,7 @@ finish_backward (struct symbol *function)
   pc = get_frame_pc (get_current_frame ());
 
   if (find_pc_partial_function (pc, NULL, &func_addr, NULL) == 0)
-    internal_error (__FILE__, __LINE__,
-		    _("Finish: couldn't find function."));
+    error (_("Cannot find bounds of current function"));
 
   sal = find_pc_line (func_addr, 0);
 

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-07-08  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* gdb.btrace/segv.exp: New.
+	* gdb.btrace/segv.c: New.
+
 2014-07-02  Luis Machado  <lgustavo@codesourcery.com>
 
 	* gdb.trace/entry-values.exp: Handle powerpc-specific branch

gdb/testsuite/gdb.btrace/segv.c

@@ -0,0 +1,32 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 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/>.  */
+
+static int (*fun)(int);
+
+int
+test (void)
+{
+  return fun (42); /* test.call */
+}
+
+int
+main (void)
+{
+  return test ();
+}

gdb/testsuite/gdb.btrace/segv.exp

@@ -0,0 +1,45 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2014 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 }
+
+# start inferior
+standard_testfile
+if [prepare_for_testing $testfile.exp $testfile $srcfile] {
+    return -1
+}
+if ![runto_main] {
+    return -1
+}
+
+# trace the test code
+gdb_test_no_output "record btrace"
+gdb_test "continue" [join [list \
+  "Program received signal SIGSEGV, Segmentation fault\." \
+  "0x0* in \\\?\\\? \\\(\\\)" \
+  ] "\r\n"] "cont to segv"
+
+# we cannot do any high-level stepping
+gdb_test "reverse-finish" "Cannot find bounds of current function"
+gdb_test "reverse-next" "Cannot find bounds of current function"
+gdb_test "reverse-step" "Cannot find bounds of current function"
+
+# but we can do instruction stepping
+gdb_test "reverse-stepi" "test\.call\[^\\\r\\\n\]*"