[PATCH v5] Change message when reaching end of reverse history.

[PATCH v5] Change message when reaching end of reverse history.

[Alex Chronopoulos]

In a record session, when we move backward, GDB switches from normal
execution to simulation. Moving forward again, the emulation continues
until the end of the reverse history. When the end is reached, the
execution stops, and a warning message is shown. This message has been
modified to indicate that the forward emulation has reached the end, but
the execution can continue as normal, and the recording will also continue.

Before this patch, the warning message shown in that case was the same as
in the reverse case. This meant that when the end of history was reached in
either backward or forward emulation, the same message was displayed:

"No more reverse-execution history."

This message has changed for these two cases. Backward emulation:

"Reached end of recorded history; stopping.
Backward execution from here not possible."

Forward emulation:

"Reached end of recorded history; stopping.
Following forward execution will be added to history."

The reason for this change is that the initial message was deceiving, for
the forward case, making the user believe that forward debugging could not
continue.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31224
---
 gdb/NEWS                                      |  5 +++
 gdb/infrun.c                                  |  9 +++++-
 gdb/testsuite/gdb.btrace/non-stop.exp         | 32 ++++++++++++-------
 gdb/testsuite/gdb.reverse/break-precsave.exp  |  6 ++--
 gdb/testsuite/gdb.reverse/break-reverse.exp   |  4 +--
 .../gdb.reverse/machinestate-precsave.exp     |  2 +-
 gdb/testsuite/gdb.reverse/sigall-precsave.exp |  2 +-
 7 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 47677cb773a..ebec7d0a1bc 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -13,6 +13,11 @@
   This may cause breakage when using an incompatible libc, like uclibc or
   newlib, or an older glibc.
 
+* In a record session, when a forward emulation reaches the end of the reverse
+  history, the warning message has been changed to indicate that the end of the
+  history has been reached.  It also specifies that the forward execution can
+  continue, and the recording will also continue.
+
 *** Changes in GDB 15
 
 * The MPX commands "show/set mpx bound" have been deprecated, as Intel
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 1f32a63ad54..83030db543d 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -9266,8 +9266,15 @@ print_no_history_reason (struct ui_out *uiout)
 {
   if (uiout->is_mi_like_p ())
     uiout->field_string ("reason", async_reason_lookup (EXEC_ASYNC_NO_HISTORY));
+  else if (execution_direction == EXEC_FORWARD)
+    uiout->text ("\nReached end of recorded history; stopping.\nFollowing "
+		 "forward execution will be added to history.\n");
   else
-    uiout->text ("\nNo more reverse-execution history.\n");
+    {
+      gdb_assert (execution_direction == EXEC_REVERSE);
+      uiout->text ("\nReached end of recorded history; stopping.\nBackward "
+		   "execution from here not possible.\n");
+    }
 }
 
 /* Print current location without a level number, if we have changed
diff --git a/gdb/testsuite/gdb.btrace/non-stop.exp b/gdb/testsuite/gdb.btrace/non-stop.exp
index 62c940e4cd6..5e43545f6a9 100644
--- a/gdb/testsuite/gdb.btrace/non-stop.exp
+++ b/gdb/testsuite/gdb.btrace/non-stop.exp
@@ -79,16 +79,26 @@ proc gdb_cont_to_bp_line { line threads nthreads } {
         $nthreads
 }
 
-proc gdb_cont_to_no_history { threads cmd nthreads } {
+proc gdb_cont_to_no_history_backward { threads cmd nthreads } {
     gdb_cont_to $threads $cmd \
         [multi_line \
-             "No more reverse-execution history\." \
+             "Reached end of recorded.*Backward execution.*" \
              "\[^\\\r\\\n\]*" \
              "\[^\\\r\\\n\]*" \
             ] \
         $nthreads
 }
 
+proc gdb_cont_to_no_history_forward { threads cmd nthreads } {
+    gdb_cont_to $threads $cmd \
+	[multi_line \
+	     "Reached end of recorded.*Following forward.*" \
+	     "\[^\\\r\\\n\]*" \
+	     "\[^\\\r\\\n\]*" \
+	    ] \
+	$nthreads
+}
+
 # trace the code between the two breakpoints
 with_test_prefix "prepare" {
     gdb_cont_to_bp_line "$srcfile:$bp_1" all 2
@@ -176,14 +186,14 @@ with_test_prefix "reverse-step" {
 with_test_prefix "continue" {
     with_test_prefix "thread 1" {
 	with_test_prefix "continue" {
-	    gdb_cont_to_no_history 1 "continue" 1
+	    gdb_cont_to_no_history_forward 1 "continue" 1
 	    gdb_test "thread apply 1 info record" \
 		".*Recorded \[0-9\]+ instructions \[^\\\r\\\n\]*"
 	    gdb_test "thread apply 2 info record" \
 		".*Replay in progress\.  At instruction 5\."
 	}
 	with_test_prefix "reverse-continue" {
-	    gdb_cont_to_no_history 1 "reverse-continue" 1
+	    gdb_cont_to_no_history_backward 1 "reverse-continue" 1
 	    gdb_test "thread apply 1 info record" \
 		".*Replay in progress\.  At instruction 1\."
 	    gdb_test "thread apply 2 info record" \
@@ -193,14 +203,14 @@ with_test_prefix "continue" {
 
     with_test_prefix "thread 2" {
 	with_test_prefix "continue" {
-	    gdb_cont_to_no_history 2 "continue" 1
+	    gdb_cont_to_no_history_forward 2 "continue" 1
 	    gdb_test "thread apply 1 info record" \
 		".*Replay in progress\.  At instruction 1\."
 	    gdb_test "thread apply 2 info record" \
 		".*Recorded \[0-9\]+ instructions \[^\\\r\\\n\]*"
 	}
 	with_test_prefix "reverse-continue" {
-	    gdb_cont_to_no_history 2 "reverse-continue" 1
+	    gdb_cont_to_no_history_backward 2 "reverse-continue" 1
 	    gdb_test "thread apply 1 info record" \
 		".*Replay in progress\.  At instruction 1\."
 	    gdb_test "thread apply 2 info record" \
@@ -215,8 +225,8 @@ with_test_prefix "no progress" {
         gdb_test "thread apply 1 record goto end" ".*"
         gdb_test "thread apply 2 record goto begin" ".*"
 
-        gdb_cont_to_no_history 1 "continue" 1
-        gdb_cont_to_no_history 1 "step" 1
+        gdb_cont_to_no_history_forward 1 "continue" 1
+        gdb_cont_to_no_history_forward 1 "step" 1
         gdb_test "thread apply 1 info record" \
             ".*Recorded \[0-9\]+ instructions \[^\\\r\\\n\]*"
         gdb_test "thread apply 2 info record" \
@@ -227,8 +237,8 @@ with_test_prefix "no progress" {
         gdb_test "thread apply 1 record goto begin" ".*"
         gdb_test "thread apply 2 record goto end" ".*"
 
-        gdb_cont_to_no_history 2 "continue" 1
-        gdb_cont_to_no_history 2 "step" 1
+        gdb_cont_to_no_history_forward 2 "continue" 1
+        gdb_cont_to_no_history_forward 2 "step" 1
         gdb_test "thread apply 1 info record" \
             ".*Replay in progress\.  At instruction 1\."
         gdb_test "thread apply 2 info record" \
@@ -238,7 +248,7 @@ with_test_prefix "no progress" {
     with_test_prefix "all" {
         gdb_test "thread apply all record goto begin" ".*"
 
-        gdb_cont_to_no_history all "continue" 2
+        gdb_cont_to_no_history_forward all "continue" 2
         gdb_test "thread apply 1 info record" \
             ".*Recorded \[0-9\]+ instructions \[^\\\r\\\n\]*"
         gdb_test "thread apply 2 info record" \
diff --git a/gdb/testsuite/gdb.reverse/break-precsave.exp b/gdb/testsuite/gdb.reverse/break-precsave.exp
index b9d94681247..6d9b312185f 100644
--- a/gdb/testsuite/gdb.reverse/break-precsave.exp
+++ b/gdb/testsuite/gdb.reverse/break-precsave.exp
@@ -73,7 +73,7 @@ proc precsave_tests {} {
 	-re ".*Breakpoint $decimal,.*$srcfile:$end_location.*$gdb_prompt $"  {
 	    pass "go to end of main forward"
 	}
-	-re "No more reverse-execution history.* end of main .*$gdb_prompt $" {
+	-re -wrap "Reached end of recorded.*Following forward.* end of main .*" {
 	    pass "go to end of main forward"
 	}
     }
@@ -87,7 +87,7 @@ proc precsave_tests {} {
 	-re ".*Breakpoint $decimal,.*$srcfile:$main_location.*$gdb_prompt $" {
 	    pass "main backward"
 	}
-	-re "No more reverse-execution history.* break in main .*$gdb_prompt $" {
+	-re -wrap "Reached end of recorded.*Backward execution.* break in main .*" {
 	    pass "main backward"
 	}
     }
@@ -103,7 +103,7 @@ proc precsave_tests {} {
 	-re ".*Breakpoint $decimal,.*$srcfile:$end_location.*$gdb_prompt $" {
 	    pass "end of record log"
 	}
-	-re "No more reverse-execution history.* end of main .*$gdb_prompt $" {
+	-re -wrap "Reached end of recorded.*Following forward.* end of main .*" {
 	    pass "end of record log"
 	}
     }
diff --git a/gdb/testsuite/gdb.reverse/break-reverse.exp b/gdb/testsuite/gdb.reverse/break-reverse.exp
index 1dd327ca654..66e9712707f 100644
--- a/gdb/testsuite/gdb.reverse/break-reverse.exp
+++ b/gdb/testsuite/gdb.reverse/break-reverse.exp
@@ -64,7 +64,7 @@ gdb_test_multiple "continue" "main backward" {
     -re ".*Breakpoint $decimal,.*$srcfile:$main_location.*$gdb_prompt $" {
 	pass "main backward"
     }
-    -re "No more reverse-execution history.* break in main .*$gdb_prompt $" {
+    -re -wrap "Reached end of recorded history.*Backward execution.*" {
 	pass "main backward"
     }
 }
@@ -80,7 +80,7 @@ gdb_test_multiple "continue" "end of record log" {
     -re ".*Breakpoint $decimal,.*$srcfile:$end_location.*$gdb_prompt $" {
 	pass "end of record log"
     }
-    -re "No more reverse-execution history.* end of main .*$gdb_prompt $" {
+    -re -wrap "Reached end of recorded history.*Following forward.*" {
 	pass "end of record log"
     }
 }
diff --git a/gdb/testsuite/gdb.reverse/machinestate-precsave.exp b/gdb/testsuite/gdb.reverse/machinestate-precsave.exp
index 19c5934bfdf..cedca0f9b65 100644
--- a/gdb/testsuite/gdb.reverse/machinestate-precsave.exp
+++ b/gdb/testsuite/gdb.reverse/machinestate-precsave.exp
@@ -85,7 +85,7 @@ gdb_test_multiple "continue" "go to end of main forward" {
     -re ".*Breakpoint $decimal,.*$srcfile:$endmain.*$gdb_prompt $"  {
 	pass "go to end of main forward"
     }
-    -re "No more reverse-execution history.* end main .*$gdb_prompt $" {
+    -re -wrap "Reached end of recorded history.*Following forward.*" {
 	pass "go to end of main forward"
     }
 }
diff --git a/gdb/testsuite/gdb.reverse/sigall-precsave.exp b/gdb/testsuite/gdb.reverse/sigall-precsave.exp
index e5890ad7af7..aab4551c874 100644
--- a/gdb/testsuite/gdb.reverse/sigall-precsave.exp
+++ b/gdb/testsuite/gdb.reverse/sigall-precsave.exp
@@ -128,7 +128,7 @@ proc test_one_sig_reverse {prevsig} {
 		xfail "$testmsg (handled)"
 	    }
 	}
-	-re "No more reverse-execution history.*kill.*$gdb_prompt " {
+	-re "Reached end of recorded history.*Backward execution.*kill.*$gdb_prompt " {
 	    if {$saw_signal} {
 		pass "$testmsg (handled)"
 	    } else {
-- 
2.42.0

Re: [PATCH v5] Change message when reaching end of reverse history.

[Eli Zaretskii]

> From: Alex Chronopoulos <achronop@gmail.com>
> Cc: Alex Chronopoulos <achronop@gmail.com>
> Date: Mon,  8 Jul 2024 21:27:30 +0200
> 
> In a record session, when we move backward, GDB switches from normal
> execution to simulation. Moving forward again, the emulation continues
> until the end of the reverse history. When the end is reached, the
> execution stops, and a warning message is shown. This message has been
> modified to indicate that the forward emulation has reached the end, but
> the execution can continue as normal, and the recording will also continue.
> 
> Before this patch, the warning message shown in that case was the same as
> in the reverse case. This meant that when the end of history was reached in
> either backward or forward emulation, the same message was displayed:
> 
> "No more reverse-execution history."
> 
> This message has changed for these two cases. Backward emulation:
> 
> "Reached end of recorded history; stopping.
> Backward execution from here not possible."
> 
> Forward emulation:
> 
> "Reached end of recorded history; stopping.
> Following forward execution will be added to history."
> 
> The reason for this change is that the initial message was deceiving, for
> the forward case, making the user believe that forward debugging could not
> continue.
> 
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31224
> ---
>  gdb/NEWS                                      |  5 +++
>  gdb/infrun.c                                  |  9 +++++-
>  gdb/testsuite/gdb.btrace/non-stop.exp         | 32 ++++++++++++-------
>  gdb/testsuite/gdb.reverse/break-precsave.exp  |  6 ++--
>  gdb/testsuite/gdb.reverse/break-reverse.exp   |  4 +--
>  .../gdb.reverse/machinestate-precsave.exp     |  2 +-
>  gdb/testsuite/gdb.reverse/sigall-precsave.exp |  2 +-
>  7 files changed, 41 insertions(+), 19 deletions(-)

I'm not sure this change warrants a NEWS entry, but if it does, the
NEWS part is approved.  Thanks.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>

RE: [PATCH v5] Change message when reaching end of reverse history.

[Metzger, Markus T]

> gdb/NEWS                                      |  5 +++
> gdb/infrun.c                                  |  9 +++++-
> gdb/testsuite/gdb.btrace/non-stop.exp         | 32 ++++++++++++-------
> gdb/testsuite/gdb.reverse/break-precsave.exp  |  6 ++--
> gdb/testsuite/gdb.reverse/break-reverse.exp   |  4 +--
> .../gdb.reverse/machinestate-precsave.exp     |  2 +-
> gdb/testsuite/gdb.reverse/sigall-precsave.exp |  2 +-
> 7 files changed, 41 insertions(+), 19 deletions(-)

When I grep for 'No more reverse' I find more hits in gdb.btrace.


>+proc gdb_cont_to_no_history_backward { threads cmd nthreads } {
>     gdb_cont_to $threads $cmd \
>         [multi_line \
>-             "No more reverse-execution history\." \
>+             "Reached end of recorded.*Backward execution.*" \

If we just scanned for "Reached end of recorded history", this would be
a one-line change.

Regards,
Markus.

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Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
Managing Directors: Sean Fennelly, Jeffrey Schneiderman, Tiffany Doon Silva
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928

Re: [PATCH v5] Change message when reaching end of reverse history.

[Alex Chronopoulos]

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> When I grep for 'No more reverse' I find more hits in gdb.btrace.

Thank you, updated, I am about to push a v6.

> If we just scanned for "Reached end of recorded history", this would be
> a one-line change.

That's right but now the direction is also tested which is not bad.

Regards,
Alex

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