[PATCH V2 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.

gdb/ChangeLog:

  2014-10-10  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.
---
 gdb/ChangeLog |   10 +++++++++
 gdb/probe.c   |   63 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 66 insertions(+), 7 deletions(-)

diff --git a/gdb/probe.c b/gdb/probe.c
index 3b8882e..47f5dc2 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
@@ -517,6 +559,9 @@ 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;
@@ -529,16 +574,16 @@ 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,
 				       VEC_length (bound_probe_s, probes),
@@ -571,10 +616,12 @@ 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);
@@ -604,6 +651,8 @@ 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);
-- 
1.7.10.4