gdb, btrace: fix pr19340

GDB fails with an assertion when stopping recording on a replaying thread
and then resuming that thread.  Stopping recording left the thread
replaying but the record target is gone.

Stop replaying all threads in the selected inferior before stopping recording.

If the selected thread had been replaying, print the (potentially updated)
location.

I had to change the stepping test slightly to account for different
compilers generating slightly different debug information, so when
stepping the 'return 0' after 'record stop' I would end up in a different
location depending on which compiler I used.  The test still covers all
stepping commands.

Fixes PR gdb/19340.

2 files changed, 32 insertions, 7 deletions

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 997f442..1a5009c 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -415,11 +415,28 @@ record_btrace_target::stop_recording ()
 {
   DEBUG ("stop recording");
 
+  /* Remember the selected thread if it exists and is replaying.  */
+  thread_info *curr = nullptr;
+  if (inferior_ptid.lwp_p ())
+    {
+      curr = inferior_thread ();
+      if (!btrace_is_replaying (curr))
+	curr = nullptr;
+    }
+
+  record_stop_replaying ();
   record_btrace_auto_disable ();
 
   for (thread_info *tp : current_inferior ()->non_exited_threads ())
     if (tp->btrace.target != NULL)
       btrace_disable (tp);
+
+  /* Print the updated location in case we had stopped a replaying thread.  */
+  if (curr != nullptr)
+    {
+      curr->set_stop_pc (regcache_read_pc (get_thread_regcache (curr)));
+      print_stack_frame (get_selected_frame (), 1, SRC_AND_LOC, 1);
+    }
 }
 
 /* The disconnect method of target record-btrace.  */
diff --git a/gdb/testsuite/gdb.btrace/step.exp b/gdb/testsuite/gdb.btrace/step.exp
index 0adc18b..ed6d214 100644
--- a/gdb/testsuite/gdb.btrace/step.exp
+++ b/gdb/testsuite/gdb.btrace/step.exp
@@ -31,18 +31,26 @@ if ![runto_main] {
 # trace the call to the test function
 with_test_prefix "record" {
     gdb_test_no_output "record btrace"
-    gdb_test "next"
+    gdb_test "step"
+    gdb_test "next 2"
 }
 
 # let's step around a bit
 with_test_prefix "replay" {
-    gdb_test "reverse-next" ".*main\.2.*" "reverse-next.1"
+    gdb_test "reverse-finish" ".*main\.2.*" "reverse-finish.1"
     gdb_test "step" ".*fun4\.2.*" "step.1"
     gdb_test "next" ".*fun4\.3.*" "next.1"
     gdb_test "step" ".*fun2\.2.*" "step.2"
-    gdb_test "finish" ".*fun4\.4.*" "finish.1"
-    gdb_test "reverse-step" ".*fun2\.3.*" "reverse-step.1"
-    gdb_test "reverse-finish" ".*fun4\.3.*" "reverse-finish.1"
-    gdb_test "reverse-next" ".*fun4\.2.*" "reverse-next.2"
-    gdb_test "reverse-finish" ".*main\.2.*" "reverse-finish.2"
+    gdb_test "reverse-finish" ".*fun4\.3.*" "reverse-finish.2"
+    gdb_test "reverse-step" ".*fun1\.2.*" "reverse-step.1"
+    gdb_test "finish" ".*fun4\.3.*" "finish.1"
+    gdb_test "reverse-next" ".*fun4\.2.*" "reverse-next.1"
+    gdb_test "reverse-finish" ".*main\.2.*" "reverse-finish.3"
+}
+
+# stop recording and try to step live (pr19340)
+with_test_prefix "live" {
+    gdb_test "record stop" "fun4\.4.*Process record is stopped.*"
+    gdb_test "reverse-next" "Target .* does not support this command.*"
+    gdb_test "step" ".*fun3\.2.*"
 }