Re: [PATCH 1/2] gdb: get_frame_language now takes a frame parameter.

[Andrew Burgess <andrew dot burgess at embecosm dot com>]

* Pedro Alves <palves@redhat.com> [2015-08-04 17:02:42 +0100]:

> On 08/04/2015 04:40 PM, Andrew Burgess wrote:

> >
> > -  flang = get_frame_language ();
> > -  if (flang != language_unknown &&
> > -      language_mode == language_mode_manual &&
> > -      current_language->la_language != flang)
> > -    printf_filtered ("%s\n", lang_frame_mismatch_warn);
> > +  if (target_has_execution)
> 
> target_has_execution can't be right.  What about core files?

Switched to has_stack_frames, which, given we're working with stack
frames seems like a much better check.

> 
> > +    {
> > +      frame = get_selected_frame (NULL);
> > +      flang = get_frame_language (frame);
> > +      if (flang != language_unknown &&
> > +	  language_mode == language_mode_manual &&
> > +	  current_language->la_language != flang)
> 
> Please put the &&'s at the beginning of the next line while at it.

Done.

> >  
> >    /* First make sure that a new frame has been selected, in case the
> >       command or the hooks changed the program state.  */
> > -  deprecated_safe_get_selected_frame ();
> > +  frame = deprecated_safe_get_selected_frame ();
> >    if (current_language != expected_language)
> >      {
> >        if (language_mode == language_mode_auto && info_verbose)
> > @@ -348,11 +349,11 @@ check_frame_language_change (void)
> >    /* FIXME: This should be cacheing the frame and only running when
> >       the frame changes.  */
> >  
> > -  if (has_stack_frames ())
> > +  if (has_stack_frames () && frame != NULL)
> 
> If has_stack_frames() returns true, how can FRAME be NULL?

Good point. Pointless check removed.

New version below.

Thanks,
Andrew

---

As part of a drive to remove deprecated_safe_get_selected_frame, make
the get_frame_language function take a frame parameter.  Given the name
of the function this actually seems to make a lot of sense.

The task of fetching a suitable frame is then passed to the calling
functions.  For get_frame_language there are not many callers, these are
updated to get the selected frame in a suitable way.

gdb/ChangeLog:

	* language.c (show_language_command): Find selected frame before
	asking for the language of that frame.
	(set_language_command): Likewise.
	* language.h (get_frame_language): Add frame parameter.
	* stack.c (get_frame_language): Add frame parameter, assert
	parameter is not NULL, update comment and reindent.
	* top.c (check_frame_language_change): Pass the selected frame
	into get_frame_language.
---
 gdb/ChangeLog  | 11 +++++++++++
 gdb/language.c | 33 +++++++++++++++++++++++--------
 gdb/language.h |  2 +-
 gdb/stack.c    | 61 ++++++++++++++++++++++++++++------------------------------
 gdb/top.c      |  5 +++--
 5 files changed, 69 insertions(+), 43 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index af41072..223d2e5 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,14 @@
+2015-08-04  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* language.c (show_language_command): Find selected frame before
+	asking for the language of that frame.
+	(set_language_command): Likewise.
+	* language.h (get_frame_language): Add frame parameter.
+	* stack.c (get_frame_language): Add frame parameter, assert
+	parameter is not NULL, update comment and reindent.
+	* top.c (check_frame_language_change): Pass the selected frame
+	into get_frame_language.
+
 2015-08-04  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	* infcmd.c (signal_command): Call do_cleanups for args_chain.
diff --git a/gdb/language.c b/gdb/language.c
index a8b432e..75d4497 100644
--- a/gdb/language.c
+++ b/gdb/language.c
@@ -118,7 +118,8 @@ static void
 show_language_command (struct ui_file *file, int from_tty,
 		       struct cmd_list_element *c, const char *value)
 {
-  enum language flang;		/* The language of the current frame.  */
+  struct frame_info *frame;
+  enum language flang;		/* The language of the frame.  */
 
   if (language_mode == language_mode_auto)
     fprintf_filtered (gdb_stdout,
@@ -130,11 +131,15 @@ show_language_command (struct ui_file *file, int from_tty,
 		      _("The current source language is \"%s\".\n"),
 		      current_language->la_name);
 
-  flang = get_frame_language ();
-  if (flang != language_unknown &&
-      language_mode == language_mode_manual &&
-      current_language->la_language != flang)
-    printf_filtered ("%s\n", lang_frame_mismatch_warn);
+  if (has_stack_frames ())
+    {
+      frame = get_selected_frame (NULL);
+      flang = get_frame_language (frame);
+      if (flang != language_unknown
+	  && language_mode == language_mode_manual
+	  && current_language->la_language != flang)
+	printf_filtered ("%s\n", lang_frame_mismatch_warn);
+    }
 }
 
 /* Set command.  Change the current working language.  */
@@ -142,7 +147,7 @@ static void
 set_language_command (char *ignore, int from_tty, struct cmd_list_element *c)
 {
   int i;
-  enum language flang;
+  enum language flang = language_unknown;
 
   /* Search the list of languages for a match.  */
   for (i = 0; i < languages_size; i++)
@@ -155,7 +160,19 @@ set_language_command (char *ignore, int from_tty, struct cmd_list_element *c)
 	      /* Enter auto mode.  Set to the current frame's language, if
                  known, or fallback to the initial language.  */
 	      language_mode = language_mode_auto;
-	      flang = get_frame_language ();
+	      TRY
+		{
+		  struct frame_info *frame;
+
+		  frame = get_selected_frame (NULL);
+		  flang = get_frame_language (frame);
+		}
+	      CATCH (ex, RETURN_MASK_ERROR)
+		{
+		  flang = language_unknown;
+		}
+	      END_CATCH
+
 	      if (flang != language_unknown)
 		set_language (flang);
 	      else
diff --git a/gdb/language.h b/gdb/language.h
index 4ecb103..8782ef0 100644
--- a/gdb/language.h
+++ b/gdb/language.h
@@ -544,7 +544,7 @@ extern const char *language_str (enum language);
 
 extern void add_language (const struct language_defn *);
 
-extern enum language get_frame_language (void);	/* In stack.c */
+extern enum language get_frame_language (struct frame_info *frame);	/* In stack.c */
 
 /* Check for a language-specific trampoline.  */
 
diff --git a/gdb/stack.c b/gdb/stack.c
index b4cfdbd..31a723d 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -2560,46 +2560,43 @@ func_command (char *arg, int from_tty)
     select_and_print_frame (frame);
 }
 
-/* Gets the language of the current frame.  */
+/* Gets the language of FRAME.  */
 
 enum language
-get_frame_language (void)
+get_frame_language (struct frame_info *frame)
 {
-  struct frame_info *frame = deprecated_safe_get_selected_frame ();
+  CORE_ADDR pc = 0;
+  int pc_p = 0;
 
-  if (frame)
-    {
-      CORE_ADDR pc = 0;
-      int pc_p = 0;
+  gdb_assert (frame!= NULL);
 
-      /* We determine the current frame language by looking up its
-         associated symtab.  To retrieve this symtab, we use the frame
-         PC.  However we cannot use the frame PC as is, because it
-         usually points to the instruction following the "call", which
-         is sometimes the first instruction of another function.  So
-         we rely on get_frame_address_in_block(), it provides us with
-         a PC that is guaranteed to be inside the frame's code
-         block.  */
+    /* We determine the current frame language by looking up its
+       associated symtab.  To retrieve this symtab, we use the frame
+       PC.  However we cannot use the frame PC as is, because it
+       usually points to the instruction following the "call", which
+       is sometimes the first instruction of another function.  So
+       we rely on get_frame_address_in_block(), it provides us with
+       a PC that is guaranteed to be inside the frame's code
+       block.  */
 
-      TRY
-	{
-	  pc = get_frame_address_in_block (frame);
-	  pc_p = 1;
-	}
-      CATCH (ex, RETURN_MASK_ERROR)
-	{
-	  if (ex.error != NOT_AVAILABLE_ERROR)
-	    throw_exception (ex);
-	}
-      END_CATCH
+  TRY
+    {
+      pc = get_frame_address_in_block (frame);
+      pc_p = 1;
+    }
+  CATCH (ex, RETURN_MASK_ERROR)
+    {
+      if (ex.error != NOT_AVAILABLE_ERROR)
+	throw_exception (ex);
+    }
+  END_CATCH
 
-      if (pc_p)
-	{
-	  struct compunit_symtab *cust = find_pc_compunit_symtab (pc);
+  if (pc_p)
+    {
+      struct compunit_symtab *cust = find_pc_compunit_symtab (pc);
 
-	  if (cust != NULL)
-	    return compunit_language (cust);
-	}
+      if (cust != NULL)
+	return compunit_language (cust);
     }
 
   return language_unknown;
diff --git a/gdb/top.c b/gdb/top.c
index 3e88ac6..0130acf 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -329,10 +329,11 @@ void
 check_frame_language_change (void)
 {
   static int warned = 0;
+  struct frame_info *frame;
 
   /* First make sure that a new frame has been selected, in case the
      command or the hooks changed the program state.  */
-  deprecated_safe_get_selected_frame ();
+  frame = deprecated_safe_get_selected_frame ();
   if (current_language != expected_language)
     {
       if (language_mode == language_mode_auto && info_verbose)
@@ -352,7 +353,7 @@ check_frame_language_change (void)
     {
       enum language flang;
 
-      flang = get_frame_language ();
+      flang = get_frame_language (frame);
       if (!warned
 	  && flang != language_unknown
 	  && flang != current_language->la_language)
-- 
2.4.0