Re: [RFA/ada] Improve is_known_support_routine

[Joel Brobecker <brobecker@adacore.com>]

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I noticed while cleaning up the same code that I forgot to delete
a local variable that became unused.  Here is a new patch.
Rested on x86-linux.

> A customer just reported us an issue that we never noticed before.
> It can be reduced to this:
> 
>     procedure Foo is
>     begin
>        raise Constraint_Error;
>     end Foo;
> 
> We're setting an exception catchpoint. Then we debug from a location
> that's not where the sources are ("cd subdir"):
> 
>     % gnatmake -g foo
>     % gdb foo
>     (gdb) cd subdir
>     (gdb) catch exception
>     (gdb) run
>     Catchpoint 1, CONSTRAINT_ERROR at <__gnat_raise_nodefer_with_msg>
>        (e=0x805844c) at a-except.adb:818
>     818     a-except.adb: No such file or directory.
>             in a-except.adb
>     (gdb) f
>     #0  <__gnat_raise_nodefer_with_msg> (e=0x805844c) at a-except.adb:818
>     818     in a-except.adb
> 
> As you see, the debugger did not go up the call stack to foo.adb.
> Here is the the expected output:
> 
>     (gdb) run
>     Catchpoint 1, CONSTRAINT_ERROR at 0x080497fe in foo () at foo.adb:3
>     3          raise Constraint_Error;
>     (gdb) f
>     #4  0x080497fe in foo () at foo.adb:3
>     3          raise Constraint_Error;
> 
> The is_known_support_routine identifies any frame for which we cannot
> find the source file. The check we currently have in place is a bit too
> simplistic, so I replaced it with the function we use to locate source
> files:
> 
> -  if (stat (sal.symtab->filename, &st))
> +  if (symtab_to_fullname (sal.symtab) == NULL)
> 
> Unfortunately, I cannot reproduce this within our testsuite, because
> we use GNAT project files to build the executable. One of the side effects
> of using a project file is that the compiler is called with the absolute
> filename rather than a relative filename. As a result, symtab->filename
> contains the absolute path, and hence the stat call always succeeds.
> 
> Because we offer the option of building GDB out of tree, apart from
> creating on the fly the setup in a temporary directory, followed by
> compiling and then testing there, I am not sure how to create a testcase
> for this issue... We were able to add a testcase in our testsuite,
> however, as it uses another type of technology that allows us to build
> our example programs without project files.
> 
> For now, I propose that we commit this patch without adding a testcase.
> I think that the symtab_to_fullname routine is already fairly
> extensively tested as it just a wrapper around a fairly central routine
> in source location.
> 
> 2007-01-06  Joel Brobecker  <brobecker@adacore.com>
> 
>         * ada-lang.c: Add include of source.h.
>         (is_known_support_routine): Improve the check verifying that the file
>         associated to this frame exists.
>         * Makefile.in (ada-lang.o): Add dependency on source.h.
> 
> Tested on x86-linux. Ok to apply?

Thank you,
-- 
Joel

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Index: ada-lang.c
===================================================================
RCS file: /cvs/src/src/gdb/ada-lang.c,v
retrieving revision 1.88
diff -u -p -r1.88 ada-lang.c
--- ada-lang.c	4 Jan 2007 06:31:51 -0000	1.88
+++ ada-lang.c	7 Jan 2007 07:11:44 -0000
@@ -55,6 +55,7 @@ Boston, MA 02110-1301, USA.  */
 #include "exceptions.h"
 #include "annotate.h"
 #include "valprint.h"
+#include "source.h"
 
 #ifndef ADA_RETAIN_DOTS
 #define ADA_RETAIN_DOTS 0
@@ -9056,7 +9057,6 @@ is_known_support_routine (struct frame_i
     = find_pc_line (get_frame_pc (frame), pc_is_after_call);
   char *func_name;
   int i;
-  struct stat st;
 
   /* The heuristic:
      1. The symtab is null (indicating no debugging symbols)
@@ -9072,7 +9072,7 @@ is_known_support_routine (struct frame_i
      symbols; in this case, the filename referenced by these symbols
      does not exists.  */
 
-  if (stat (sal.symtab->filename, &st))
+  if (symtab_to_fullname (sal.symtab) == NULL)
     return 1;
 
   for (i = 0; known_runtime_file_name_patterns[i] != NULL; i += 1)
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.870
diff -u -p -r1.870 Makefile.in
--- Makefile.in	4 Jan 2007 22:11:44 -0000	1.870
+++ Makefile.in	7 Jan 2007 07:11:52 -0000
@@ -1696,7 +1696,8 @@ ada-lang.o: ada-lang.c $(defs_h) $(gdb_s
 	$(inferior_h) $(symfile_h) $(objfiles_h) $(breakpoint_h) \
 	$(gdbcore_h) $(hashtab_h) $(gdb_obstack_h) $(ada_lang_h) \
 	$(completer_h) $(gdb_stat_h) $(ui_out_h) $(block_h) $(infcall_h) \
-	$(dictionary_h) $(exceptions_h) $(annotate_h) $(valprint_h)
+	$(dictionary_h) $(exceptions_h) $(annotate_h) $(valprint_h) \
+	$(source_h)
 ada-typeprint.o: ada-typeprint.c $(defs_h) $(gdb_obstack_h) $(bfd_h) \
 	$(symtab_h) $(gdbtypes_h) $(expression_h) $(value_h) $(gdbcore_h) \
 	$(target_h) $(command_h) $(gdbcmd_h) $(language_h) $(demangle_h) \