[PATCH V4 1/9] Adapt `info probes' to support printing probes of different types.

["Jose E. Marchesi" <jose.marchesi@oracle.com>]

A "probe type" (backend for the probe abstraction implemented in
probe.[ch]) can extend the information printed by `info probes' by
defining additional columns.  This means that when `info probes' is
used to print all the probes regardless of their types, some of the
columns will be "not applicable" to some of the probes (like, say, the
Semaphore column only makes sense for SystemTap probes).  This patch
makes `info probes' fill these slots with "n/a" marks (currently it
breaks the table) and not include headers for which no actual probe
has been found in the list of defined probes.

This patch also adds support for a new generic column "Type", that
displays the type of each probe.  SystemTap probes identify themselves
as "stap" probes.

gdb/ChangeLog:

2015-02-02  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* probe.c (print_ui_out_not_applicables): New function.
	(exists_probe_with_pops): Likewise.
	(info_probes_for_ops): Do not include column headers for probe
	types for which no probe has been actually found on any object.
	Also invoke `print_ui_out_not_applicables' in order to match the
	column rows with the header when probes of several types are
	listed.
	Print the "Type" column.
	* probe.h (probe_ops): Added a new probe operation `type_name'.
	* stap-probe.c (stap_probe_ops): Add `stap_type_name'.
	(stap_type_name): New function.
---
 gdb/ChangeLog    |   14 ++++++++++
 gdb/probe.c      |   76 +++++++++++++++++++++++++++++++++++++++++++++++-------
 gdb/probe.h      |    6 +++++
 gdb/stap-probe.c |   12 ++++++++-
 4 files changed, 97 insertions(+), 11 deletions(-)

diff --git a/gdb/probe.c b/gdb/probe.c
index 56b5fc1..be3e656 100644
--- a/gdb/probe.c
+++ b/gdb/probe.c
@@ -410,6 +410,31 @@ gen_ui_out_table_header_info (VEC (bound_probe_s) *probes,
   do_cleanups (c);
 }
 
+/* Helper function to print not-applicable strings for all the extra
+   columns defined in a probe_ops.  */
+
+static void
+print_ui_out_not_applicables (const struct probe_ops *pops)
+{
+  struct cleanup *c;
+  VEC (info_probe_column_s) *headings = NULL;
+  info_probe_column_s *column;
+  int ix;
+
+  if (pops->gen_info_probes_table_header == NULL)
+    return;
+
+  c = make_cleanup (VEC_cleanup (info_probe_column_s), &headings);
+  pops->gen_info_probes_table_header (&headings);
+
+  for (ix = 0;
+       VEC_iterate (info_probe_column_s, headings, ix, column);
+       ++ix)
+    ui_out_field_string (current_uiout, column->field_name, _("n/a"));
+
+  do_cleanups (c);
+}
+
 /* Helper function to print extra information about a probe and an objfile
    represented by PROBE.  */
 
@@ -482,6 +507,23 @@ get_number_extra_fields (const struct probe_ops *pops)
   return n;
 }
 
+/* Helper function that returns 1 if there is a probe in PROBES
+   featuring the given POPS.  It returns 0 otherwise.  */
+
+static int
+exists_probe_with_pops (VEC (bound_probe_s) *probes,
+			const struct probe_ops *pops)
+{
+  struct bound_probe *probe;
+  int ix;
+
+  for (ix = 0; VEC_iterate (bound_probe_s, probes, ix, probe); ++ix)
+    if (probe->probe->pops == pops)
+      return 1;
+
+  return 0;
+}
+
 /* See comment in probe.h.  */
 
 void
@@ -497,6 +539,7 @@ info_probes_for_ops (const char *arg, int from_tty,
   size_t size_name = strlen ("Name");
   size_t size_objname = strlen ("Object");
   size_t size_provider = strlen ("Provider");
+  size_t size_type = strlen ("Type");
   struct bound_probe *probe;
   struct gdbarch *gdbarch = get_current_arch ();
 
@@ -517,6 +560,9 @@ info_probes_for_ops (const char *arg, int from_tty,
 	}
     }
 
+  probes = collect_probes (objname, provider, probe_name, pops);
+  make_cleanup (VEC_cleanup (probe_p), &probes);
+
   if (pops == NULL)
     {
       const struct probe_ops *po;
@@ -529,18 +575,18 @@ info_probes_for_ops (const char *arg, int from_tty,
 
 	 To do that, we iterate over all probe_ops, querying each one about
 	 its extra fields, and incrementing `ui_out_extra_fields' to reflect
-	 that number.  */
+	 that number.  But note that we ignore the probe_ops for which no probes
+         are defined with the given search criteria.  */
 
       for (ix = 0; VEC_iterate (probe_ops_cp, all_probe_ops, ix, po); ++ix)
-	ui_out_extra_fields += get_number_extra_fields (po);
+	if (exists_probe_with_pops (probes, po))
+	  ui_out_extra_fields += get_number_extra_fields (po);
     }
   else
     ui_out_extra_fields = get_number_extra_fields (pops);
 
-  probes = collect_probes (objname, provider, probe_name, pops);
-  make_cleanup (VEC_cleanup (probe_p), &probes);
   make_cleanup_ui_out_table_begin_end (current_uiout,
-				       4 + ui_out_extra_fields,
+				       5 + ui_out_extra_fields,
 				       VEC_length (bound_probe_s, probes),
 				       "StaticProbes");
 
@@ -552,15 +598,19 @@ info_probes_for_ops (const char *arg, int from_tty,
   /* What's the size of an address in our architecture?  */
   size_addr = gdbarch_addr_bit (gdbarch) == 64 ? 18 : 10;
 
-  /* Determining the maximum size of each field (`provider', `name' and
-     `objname').  */
+  /* Determining the maximum size of each field (`type', `provider',
+     `name' and `objname').  */
   for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
     {
+      const char *probe_type = probe->probe->pops->type_name (probe->probe);
+
+      size_type = max (strlen (probe_type), size_type);
       size_name = max (strlen (probe->probe->name), size_name);
       size_provider = max (strlen (probe->probe->provider), size_provider);
       size_objname = max (strlen (objfile_name (probe->objfile)), size_objname);
     }
 
+  ui_out_table_header (current_uiout, size_type, ui_left, "type", _("Type"));
   ui_out_table_header (current_uiout, size_provider, ui_left, "provider",
 		       _("Provider"));
   ui_out_table_header (current_uiout, size_name, ui_left, "name", _("Name"));
@@ -571,10 +621,12 @@ info_probes_for_ops (const char *arg, int from_tty,
       const struct probe_ops *po;
       int ix;
 
-      /* We have to generate the table header for each new probe type that we
-	 will print.  */
+      /* We have to generate the table header for each new probe type
+	 that we will print.  Note that this excludes probe types not
+	 having any defined probe with the search criteria.  */
       for (ix = 0; VEC_iterate (probe_ops_cp, all_probe_ops, ix, po); ++ix)
-	gen_ui_out_table_header_info (probes, po);
+	if (exists_probe_with_pops (probes, po))
+	  gen_ui_out_table_header_info (probes, po);
     }
   else
     gen_ui_out_table_header_info (probes, pops);
@@ -586,9 +638,11 @@ info_probes_for_ops (const char *arg, int from_tty,
   for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
     {
       struct cleanup *inner;
+      const char *probe_type = probe->probe->pops->type_name (probe->probe);
 
       inner = make_cleanup_ui_out_tuple_begin_end (current_uiout, "probe");
 
+      ui_out_field_string (current_uiout, "type",probe_type);
       ui_out_field_string (current_uiout, "provider", probe->probe->provider);
       ui_out_field_string (current_uiout, "name", probe->probe->name);
       ui_out_field_core_addr (current_uiout, "addr",
@@ -604,6 +658,8 @@ info_probes_for_ops (const char *arg, int from_tty,
 	       ++ix)
 	    if (probe->probe->pops == po)
 	      print_ui_out_info (probe->probe);
+	    else if (exists_probe_with_pops (probes, po))
+	      print_ui_out_not_applicables (po);
 	}
       else
 	print_ui_out_info (probe->probe);
diff --git a/gdb/probe.h b/gdb/probe.h
index 1dd582d..5df1976 100644
--- a/gdb/probe.h
+++ b/gdb/probe.h
@@ -113,6 +113,12 @@ struct probe_ops
 
     void (*destroy) (struct probe *probe);
 
+    /* Return a pointer to a name identifying the probe type.  This is
+       the string that will be displayed in the "Type" column of the
+       `info probes' command.  */
+
+    const char *(*type_name) (struct probe *probe);
+
     /* Function responsible for providing the extra fields that will be
        printed in the `info probes' command.  It should fill HEADS
        with whatever extra fields it needs.  If the backend doesn't need
diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
index d7d9cf1..e534b6d 100644
--- a/gdb/stap-probe.c
+++ b/gdb/stap-probe.c
@@ -1703,6 +1703,15 @@ stap_get_probes (VEC (probe_p) **probesp, struct objfile *objfile)
     }
 }
 
+/* Implementation of the type_name method.  */
+
+static const char *
+stap_type_name (struct probe *probe)
+{
+  gdb_assert (probe->pops == &stap_probe_ops);
+  return "stap";
+}
+
 static int
 stap_probe_is_linespec (const char **linespecp)
 {
@@ -1743,7 +1752,7 @@ stap_gen_info_probes_table_values (struct probe *probe_generic,
 /* SystemTap probe_ops.  */
 
 static const struct probe_ops stap_probe_ops =
-{
+  {
   stap_probe_is_linespec,
   stap_get_probes,
   stap_get_probe_address,
@@ -1754,6 +1763,7 @@ static const struct probe_ops stap_probe_ops =
   stap_set_semaphore,
   stap_clear_semaphore,
   stap_probe_destroy,
+  stap_type_name,
   stap_gen_info_probes_table_header,
   stap_gen_info_probes_table_values,
 };
-- 
1.7.10.4