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

[ppluzhnikov at google dot com (Paul Pluzhnikov)]

Greetings,

This is on the rather obvious side ...

Thanks,

--
Paul Pluzhnikov

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.



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 19:35:32 -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 = %zu\n",
+			paddress (gdbarch, code_entry->symfile_addr),
+			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 +487,15 @@ 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.  Higher numbers are more\n\
+verbose."),
+			    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 ();