[PATCHv2] gdb/testsuite: add KFAILs to gdb.reverse/step-reverse.exp

[Bruno Larsen <blarsen@redhat.com>]

On 03/11/2022 14:06, Simon Marchi wrote:
>
> On 11/3/22 05:08, Bruno Larsen wrote:
>>> I don't know the reverse stuff well, but the explanation makes sense.
>>> Do you plan on tackling this bug?  If not, can you file a bug and add a
>>> kfail?
>> Sure, I do plan on tackling this at some point, but I don't know when
>> that will be, so I filed the bug, and this is the patch to add the
>> KFAILs, thoughts?
>>
>> ---
>>
>> Recent changes to gdb.reverse/step-reverse.exp revealed the latent bug
>> PR record/29745, where we can't skip one funcion forward if we're using
>> native-gdbserver. This commit just adds kfails to the test.
>>
>> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29745
>> ---
>>   gdb/testsuite/gdb.reverse/step-reverse.exp | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/gdb/testsuite/gdb.reverse/step-reverse.exp b/gdb/testsuite/gdb.reverse/step-reverse.exp
>> index c28e1f6db4f..37e80a7d337 100644
>> --- a/gdb/testsuite/gdb.reverse/step-reverse.exp
>> +++ b/gdb/testsuite/gdb.reverse/step-reverse.exp
>> @@ -31,6 +31,7 @@ if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
>>   }
>>   
>>   runto_main
>> +set using_gdbserver [target_is_gdbserver]
>>   
>>   if [supports_process_record] {
>>       # Activate process record/replay
>> @@ -273,11 +274,25 @@ if { "$step_out" == 1 } {
>>   # Step forward over recursion again so we can test stepping over calls
>>   # inside the recursion itself.
>>   gdb_test_no_output "set exec-dir forward" "forward again to test recursion"
>> +if {$using_gdbserver} {
>> +    # gdbserver doesn't record the change of return pointer, so we can't
>> +    # next forward over functions.
>> +    setup_kfail gdb/29745 *-*-*
> There's one thing bugging me in your explanation: as far as I know,
> gdbserver does any recording, with the built-in GDB recorder (i.e. not
> btrace).  So we probably shouldn't say "gdbserver doesn't record", as
> it's not meant to record in the first place.  That would mean the
> problem is within GDB, when using the remote target.  And the check for
> the kfail should therefore use gdb_is_target_remote instead of
> target_is_gdbserver.

That makes sense. This is my first time working with gdbserver, so 
everything here is news to me.  Updated version:

---

     Recent changes to gdb.reverse/step-reverse.exp revealed the latent bug
     PR record/29745, where we can't skip one funcion forward if we're using
     native-gdbserver. This commit just adds kfails to the test.

     Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29745

diff --git a/gdb/testsuite/gdb.reverse/step-reverse.exp 
b/gdb/testsuite/gdb.reverse/step-reverse.exp
index c28e1f6db4f..d2975cffb5c 100644
--- a/gdb/testsuite/gdb.reverse/step-reverse.exp
+++ b/gdb/testsuite/gdb.reverse/step-reverse.exp
@@ -31,6 +31,7 @@ if { [prepare_for_testing "failed to prepare" 
$testfile $srcfile] } {
  }

  runto_main
+set target_remote [gdb_is_target_remote]

  if [supports_process_record] {
      # Activate process record/replay
@@ -273,11 +274,25 @@ if { "$step_out" == 1 } {
  # Step forward over recursion again so we can test stepping over calls
  # inside the recursion itself.
  gdb_test_no_output "set exec-dir forward" "forward again to test 
recursion"
+if {$target_remote} {
+    # gdb doesn't record the change of return pointer for remote targets,
+    # so we can't next forward over functions.
+    setup_kfail gdb/29745 *-*-*
+}
  gdb_test "next" "NEXT OVER THIS CALL.*" "reverse next over recursion 
again"
  gdb_test_no_output "set exec-dir reverse" "reverse again to test 
recursion"

+if {$target_remote} {
+    # Because of the above mentioned KFAIL, the inferior is now out of sync
+    setup_kfail gdb/29745 *-*-*
+}
  gdb_test "step" ".*EXIT RECURSIVE FUNCTION.*" "enter recursive function"
  set seen_recursive_call 0
+if {$target_remote} {
+    # Because of the above mentioned KFAIL, the inferior is now out of sync
+    # The fail state below will resync the inferior.
+    setup_kfail gdb/29745 *-*-*
+}
  gdb_test_multiple "next" "step over recursion inside the recursion" {
      -re -wrap ".*RECURSIVE CALL.*" {
         incr seen_recursive_call