Re: [patch] Add "debug jit" for easier tracing of JIT support internals

[Paul Pluzhnikov <ppluzhnikov@google.com>]

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On Wed, Jan 5, 2011 at 2:51 PM, Pedro Alves <pedro@codesourcery.com> wrote:

> On Wednesday 05 January 2011 21:53:11, Paul Pluzhnikov wrote:
>> One question: is '%zu' appropriate format for printing size_t ?
>
> Nope, %z is C99.  GDB is currently written in C90.
>
> AFAICS, the size_t you're talking about holds the size of an
> object on the target,

Right. It's actually specified as uint64_t in jit.h, not size_t ...

> while 'size_t' is about sizes of objects
> on the host.  E.g., on a 32-bit GDB (cross) debugging a 64-bit
> inferior, size_t will usually be a 32-bit type.  I think it'd be
> better to make that a ULONGEST throughout (and then use phex
> or pulongest)

Since this interface is frozen, and ULONGEST isn't available to clients,
I'll just cast symfile_size to ULONGEST and print it with pulongest.


On Wed, Jan 5, 2011 at 2:57 PM, Pedro Alves <pedro@codesourcery.com> wrote:

> Until and if we find a better way, an implemented show callback
> should be a requirement for all new commands.

Restored to the original ...

Thanks,

-- 
Paul Pluzhnikov


ChangeLog:

2010-01-05  Paul Pluzhnikov  <ppluzhnikov@google.com>

	* jit.c (jit_debug): New variable.
	(show_jit_debug): New function.
	(jit_register_code, jit_inferior_init): Add debug output.
	(_initialize_jit): Register "debug jit" command.


doc/ChangeLog:

2010-01-05  Paul Pluzhnikov  <ppluzhnikov@google.com>

	* gdb.texi (Debugging Output): Document "set debug jit"

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Index: jit.c
===================================================================
RCS file: /cvs/src/src/gdb/jit.c,v
retrieving revision 1.8
diff -u -p -r1.8 jit.c
--- jit.c	1 Jan 2011 15:33:09 -0000	1.8
+++ jit.c	5 Jan 2011 23:09:45 -0000
@@ -21,6 +21,8 @@
 
 #include "jit.h"
 #include "breakpoint.h"
+#include "command.h"
+#include "gdbcmd.h"
 #include "gdbcore.h"
 #include "observer.h"
 #include "objfiles.h"
@@ -48,6 +50,17 @@ static CORE_ADDR jit_descriptor_addr = 0
 
 static int registering_code = 0;
 
+/* Non-zero if we want to see trace of jit level stuff.  */
+
+static int jit_debug = 0;
+
+static void
+show_jit_debug (struct ui_file *file, int from_tty,
+		struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("JIT debugging is %s.\n"), value);
+}
+
 /* Helper cleanup function to clear an integer flag like the one above.  */
 
 static void
@@ -219,6 +232,13 @@ jit_register_code (struct gdbarch *gdbar
   const struct bfd_arch_info *b;
   CORE_ADDR *entry_addr_ptr;
 
+  if (jit_debug)
+    fprintf_unfiltered (gdb_stdlog,
+			"jit_register_code, symfile_addr = %s, "
+			"symfile_size = %s\n",
+			paddress (gdbarch, code_entry->symfile_addr),
+			pulongest ((ULONGEST) code_entry->symfile_size));
+
   nbfd = bfd_open_from_target_memory (code_entry->symfile_addr,
                                       code_entry->symfile_size, gnutarget);
   old_cleanups = make_cleanup_bfd_close (nbfd);
@@ -314,6 +334,11 @@ jit_inferior_init (struct gdbarch *gdbar
   struct jit_code_entry cur_entry;
   CORE_ADDR cur_entry_addr;
 
+  if (jit_debug)
+    fprintf_unfiltered (gdb_stdlog,
+			"jit_inferior_init, registering_code = %d\n",
+			registering_code);
+
   /* When we register code, GDB resets its breakpoints in case symbols have
      changed.  That in turn calls this handler, which makes us look for new
      code again.  To avoid being re-entered, we check this flag.  */
@@ -329,6 +354,10 @@ jit_inferior_init (struct gdbarch *gdbar
   if (reg_addr == 0)
     return;
 
+  if (jit_debug)
+    fprintf_unfiltered (gdb_stdlog, "jit_inferior_init, reg_addr = %s\n",
+			paddress (gdbarch, reg_addr));
+
   /* Lookup the descriptor symbol and cache the addr.  If it is missing, we
      assume we are not attached to a JIT and return early.  */
   desc_symbol = lookup_minimal_symbol (jit_descriptor_name, NULL, NULL);
@@ -338,6 +367,11 @@ jit_inferior_init (struct gdbarch *gdbar
   if (jit_descriptor_addr == 0)
     return;
 
+  if (jit_debug)
+    fprintf_unfiltered (gdb_stdlog,
+			"jit_inferior_init, jit_descriptor_addr = %s\n",
+			paddress (gdbarch, jit_descriptor_addr));
+
   /* Read the descriptor so we can check the version number and load any already
      JITed functions.  */
   jit_read_descriptor (gdbarch, &descriptor);
@@ -453,6 +487,14 @@ extern void _initialize_jit (void);
 void
 _initialize_jit (void)
 {
+  add_setshow_zinteger_cmd ("jit", class_maintenance, &jit_debug, _("\
+Set JIT debugging."), _("\
+Show JIT debugging."), _("\
+When non-zero, JIT debugging is enabled."),
+			    NULL,
+			    show_jit_debug,
+			    &setdebuglist, &showdebuglist);
+
   observer_attach_inferior_created (jit_inferior_created_observer);
   observer_attach_inferior_exit (jit_inferior_exit_hook);
   jit_objfile_data = register_objfile_data ();
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.783
diff -u -p -r1.783 gdb.texinfo
--- doc/gdb.texinfo	5 Jan 2011 05:09:52 -0000	1.783
+++ doc/gdb.texinfo	5 Jan 2011 23:09:46 -0000
@@ -19955,6 +19955,11 @@ The default is off.  @file{infrun.c} con
 for implementing operations such as single-stepping the inferior.
 @item show debug infrun
 Displays the current state of @value{GDBN} inferior debugging.
+@item set debug jit
+@cindex just-in-time compilation
+Turns on or off debugging messages from JIT debug support.
+@item show debug jit
+Displays the current state of @value{GDBN} JIT debugging.
 @item set debug lin-lwp
 @cindex @sc{gnu}/Linux LWP debug messages
 @cindex Linux lightweight processes