Re: [RFA] Displaced stepping just enable in non-stop mode

teawater
2008-10-10T03:38:06Z

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Hi Pedro,

Thanks for your example, I make a new patch for infrun.c and other for manual.

2008-10-10 Hui Zhu <teawater@gmail.com>

Displaced stepping can be set to
auto (enable in non-stop mode), on, off.

* infrun.c (can_use_displaced_stepping): Change type to const
char pointer.
(can_use_displaced_stepping_auto): New string.
(can_use_displaced_stepping_on): New string.
(can_use_displaced_stepping_off): New string.
(can_use_displaced_stepping_enum): New array.
(show_can_use_displaced_stepping): In auto mode, also show the
current effect of the option.
(use_displaced_stepping): Return non-zero if displaced stepping
is auto, and can be used with GDBARCH, and in non-stop mode.
Return non-zero if displaced stepping is on, and can be used
with GDBARCH.
(_initialize_infrun): "can-use-displaced-stepping" function
change to add_setshow_enum_cmd.

2008-10-10 Hui Zhu <teawater@gmail.com>

* gdb.texinfo (can-use-displaced-stepping) Describe the auto mode
setting, and make it the default.

Thanks,
Hui

On Thu, Oct 9, 2008 at 22:49, Pedro Alves <pedro@codesourcery.com> wrote:
> Hi,
>
> Thanks for doing this.
>
> On Wednesday 08 October 2008 07:10:43, teawater wrote:
>
>> -int can_use_displaced_stepping = 1;
>> +const char can_use_displaced_stepping_auto[] = "auto";
>> +const char can_use_displaced_stepping_on[] = "on";
>> +const char can_use_displaced_stepping_off[] = "off";
>> +const char *can_use_displaced_stepping_enum[] =
>> +{
>> + can_use_displaced_stepping_auto,
>> + can_use_displaced_stepping_on,
>> + can_use_displaced_stepping_off,
>> + NULL,
>> +};
>> +const char *can_use_displaced_stepping = can_use_displaced_stepping_auto;
>
> Could you make these static while you're at it, please? It was just missed
> in the old boolean setting.
>
>> static void
>> show_can_use_displaced_stepping (struct ui_file *file, int from_tty,
>> struct cmd_list_element *c,
>> @@ -567,12 +579,16 @@ Debugger's willingness to use displaced
>> "breakpoints is %s.\n"), value);
>
> Could you update this function to show what effect the auto setting
> is currently having? See breakpoint.c:show_always_inserted_mode for
> an example.
>
>> }
>>
>> -/* Return non-zero if displaced stepping is enabled, and can be used
>> +/* Return non-zero if displaced stepping is auto, and can be used
>> + with GDBARCH, and in non-stop mode.
>> + Return non-zero if displaced stepping is on, and can be used
>> with GDBARCH. */
>> static int
>> use_displaced_stepping (struct gdbarch *gdbarch)
>> {
>> - return (can_use_displaced_stepping
>> + return (((can_use_displaced_stepping == can_use_displaced_stepping_auto
>> + && non_stop)
>> + || can_use_displaced_stepping == can_use_displaced_stepping_on)
>> && gdbarch_displaced_step_copy_insn_p (gdbarch));
>> }
>>
>> @@ -4857,11 +4873,14 @@ function is skipped and the step command
>> show_step_stop_if_no_debug,
>> &setlist, &showlist);
>>
>> - add_setshow_boolean_cmd ("can-use-displaced-stepping", class_maintenance,
>> + add_setshow_enum_cmd ("can-use-displaced-stepping", class_maintenance,
>> + can_use_displaced_stepping_enum,
>> &can_use_displaced_stepping, _("\
>> Set debugger's willingness to use displaced stepping."), _("\
>> Show debugger's willingness to use displaced stepping."), _("\
>> -If zero, gdb will not use displaced stepping to step over\n\
>> +If auto, gdb will auto use displaced stepping if it need (in non-stop mode).\n\
>> +If on, gdb will use displaced stepping if such is supported by the target.\n\
>> +If off, gdb will not use displaced stepping to step over\n\
>> breakpoints, even if such is supported by the target."),
>
> This also needs to be updated in the manual. I'd suggest borrowing the text
> from breakpoint.c's "always-inserted" command description to make it a
> bit more descriptive, and mention which mode is the default. Should mostly
> be a matter of copy-paste, I think.
>
> --
> Pedro Alves
>

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--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,23 @@
+2008-10-10 Hui Zhu <teawater@gmail.com>
+
+ Displaced stepping can be set to
+ auto (enable in non-stop mode), on, off.
+
+ * infrun.c (can_use_displaced_stepping): Change type to const
+ char pointer.
+ (can_use_displaced_stepping_auto): New string.
+ (can_use_displaced_stepping_on): New string.
+ (can_use_displaced_stepping_off): New string.
+ (can_use_displaced_stepping_enum): New array.
+ (show_can_use_displaced_stepping): In auto mode, also show the
+ current effect of the option.
+ (use_displaced_stepping): Return non-zero if displaced stepping
+ is auto, and can be used with GDBARCH, and in non-stop mode.
+ Return non-zero if displaced stepping is on, and can be used
+ with GDBARCH.
+ (_initialize_infrun): "can-use-displaced-stepping" function
+ change to add_setshow_enum_cmd.
+
2008-10-09 Pedro Alves <pedro@codesourcery.com>

* remote.c (remote_wait): Rename to...
--- a/infrun.c
+++ b/infrun.c
@@ -553,26 +553,50 @@ static CORE_ADDR displaced_step_original
/* Saved contents of copy area. */
static gdb_byte *displaced_step_saved_copy;

-/* When this is non-zero, we are allowed to use displaced stepping, if
- the architecture supports it. When this is zero, we use
+/* When this is auto, we are allowed to use displaced stepping,
+ If the architecture supports it and in non-stop mode.
+ When this is on, we are allowed to use displaced stepping, if
+ the architecture supports it. When this is off, we use
traditional the hold-and-step approach. */
-int can_use_displaced_stepping = 1;
+static const char can_use_displaced_stepping_auto[] = "auto";
+static const char can_use_displaced_stepping_on[] = "on";
+static const char can_use_displaced_stepping_off[] = "off";
+static const char *can_use_displaced_stepping_enum[] =
+{
+ can_use_displaced_stepping_auto,
+ can_use_displaced_stepping_on,
+ can_use_displaced_stepping_off,
+ NULL,
+};
+static const char *can_use_displaced_stepping =
+ can_use_displaced_stepping_auto;
static void
show_can_use_displaced_stepping (struct ui_file *file, int from_tty,
struct cmd_list_element *c,
const char *value)
{
- fprintf_filtered (file, _("\
-Debugger's willingness to use displaced stepping to step over "
-"breakpoints is %s.\n"), value);
+ if (can_use_displaced_stepping == can_use_displaced_stepping_auto)
+ {
+ fprintf_filtered (file, _("\
+Debugger's willingness to use displaced stepping to step over " "breakpoints is %s (currently %s).\n"), value, non_stop ? "on" : "off");
+ }
+ else
+ {
+ fprintf_filtered (file, _("\
+Debugger's willingness to use displaced stepping to step over " "breakpoints is %s.\n"), value);
+ }
}

-/* Return non-zero if displaced stepping is enabled, and can be used
+/* Return non-zero if displaced stepping is auto, and can be used
+ with GDBARCH, and in non-stop mode.
+ Return non-zero if displaced stepping is on, and can be used
with GDBARCH. */
static int
use_displaced_stepping (struct gdbarch *gdbarch)
{
- return (can_use_displaced_stepping
+ return (((can_use_displaced_stepping == can_use_displaced_stepping_auto
+ && non_stop)
+ || can_use_displaced_stepping == can_use_displaced_stepping_on)
&& gdbarch_displaced_step_copy_insn_p (gdbarch));
}

@@ -4857,11 +4881,14 @@ function is skipped and the step command
show_step_stop_if_no_debug,
&setlist, &showlist);

- add_setshow_boolean_cmd ("can-use-displaced-stepping", class_maintenance,
+ add_setshow_enum_cmd ("can-use-displaced-stepping", class_maintenance,
+ can_use_displaced_stepping_enum,
&can_use_displaced_stepping, _("\
Set debugger's willingness to use displaced stepping."), _("\
Show debugger's willingness to use displaced stepping."), _("\
-If zero, gdb will not use displaced stepping to step over\n\
+If auto, gdb will auto use displaced stepping if it need (in non-stop mode).\n\
+If on, gdb will use displaced stepping if such is supported by the target.\n\
+If off, gdb will not use displaced stepping to step over\n\
breakpoints, even if such is supported by the target."),
NULL,
show_can_use_displaced_stepping,

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--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2008-10-10 Hui Zhu <teawater@gmail.com>
+
+ * gdb.texinfo (can-use-displaced-stepping) Describe the auto mode
+ setting, and make it the default.
+
2008-10-06 Doug Evans <dje@google.com>

* gdb.texinfo (set debug dwarf2-die): Document it.
--- a/gdb.texinfo
+++ b/gdb.texinfo
@@ -23935,16 +23935,25 @@ Shared library events.

@kindex maint set can-use-displaced-stepping
@kindex maint show can-use-displaced-stepping
-@cindex displaced stepping support
-@cindex out-of-line single-stepping
-@item maint set can-use-displaced-stepping
-@itemx maint show can-use-displaced-stepping
-Control whether or not @value{GDBN} will do @dfn{displaced stepping}
-if the target supports it. The default is on. Displaced stepping is
-a way to single-step over breakpoints without removing them from the
-inferior, by executing an out-of-line copy of the instruction that was
-originally at the breakpoint location. It is also known as
-out-of-line single-stepping.
+@table @code
+@item maint set can-use-displaced-stepping on
+If the target supports it. Gdb behaves are single-step over
+breakpoints without removing them from the inferior, by executing
+an out-of-line copy of the instruction that was originally at the
+breakpoint location. It is also known as out-of-line single-stepping.
+
+@item maint set can-use-displaced-stepping off
+Gdb behaves are single-step over breakpoints with removing them from
+the inferior.
+
+@cindex non-stop mode, and @code{breakpoint always-inserted}
+@item maint set can-use-displaced-stepping auto
+This is the default mode. If @value{GDBN} is controlling the inferior
+in non-stop mode (@pxref{Non-Stop Mode}), gdb behaves as if
+@code{can-use-displaced-stepping} mode is on. If @value{GDBN} is
+controlling the inferior in all-stop mode, @value{GDBN} behaves as if
+@code{can-use-displaced-stepping} mode is off.
+@end table

@kindex maint check-symtabs
@item maint check-symtabs