Patchwork libgcov support for profile collection in region of interest (issue6186044)

login
register
mail settings
Submitter Teresa Johnson
Date May 8, 2012, 1:40 p.m.
Message ID <20120508134024.82C1F61599@tjsboxrox.mtv.corp.google.com>
Download mbox | patch
Permalink /patch/157682/
State New
Headers show

Comments

Teresa Johnson - May 8, 2012, 1:40 p.m.
Hi Honza,

I added L_gcov_reset and L_gcov_dump for the new interfaces, and also
added a description into the gcov man page. Let me know if it looks
ok now.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

Thanks,
Teresa

2012-05-08   Teresa Johnson  <tejohnson@google.com>

	* libgcc/libgcov.c (gcov_clear, __gcov_reset): New functions.
	(__gcov_dump): Ditto.
	(gcov_dump_complete): New global variable.
	(__gcov_flush): Outline functionality now in gcov_clear.
	* gcc/gcov-io.h (__gcov_reset, __gcov_dump): Declare.
	* libgcc/Makefile.in (L_gcov_reset, L_gcov_dump): Define.
	* gcc/doc/gcov.texi: Add note on using __gcov_reset and __gcov_dump.


--
This patch is available for review at http://codereview.appspot.com/6186044
Jan Hubicka - May 8, 2012, 5:37 p.m.
> Hi Honza,
> 
> I added L_gcov_reset and L_gcov_dump for the new interfaces, and also
> added a description into the gcov man page. Let me know if it looks
> ok now.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
> 
> Thanks,
> Teresa
> 
> 2012-05-08   Teresa Johnson  <tejohnson@google.com>
> 
> 	* libgcc/libgcov.c (gcov_clear, __gcov_reset): New functions.
> 	(__gcov_dump): Ditto.
> 	(gcov_dump_complete): New global variable.
> 	(__gcov_flush): Outline functionality now in gcov_clear.
> 	* gcc/gcov-io.h (__gcov_reset, __gcov_dump): Declare.
> 	* libgcc/Makefile.in (L_gcov_reset, L_gcov_dump): Define.
> 	* gcc/doc/gcov.texi: Add note on using __gcov_reset and __gcov_dump.

It seems OK now, though gcov_clear will end up being in both gcov_reset and gcov_flush,
but I suppose it is short enough to make this issue mood
(otherwise we could make it hidden exported from gcov_flush psection)

Honza

Patch

Index: libgcc/Makefile.in
===================================================================
--- libgcc/Makefile.in	(revision 187048)
+++ libgcc/Makefile.in	(working copy)
@@ -849,7 +849,7 @@  include $(iterator)
 # Defined in libgcov.c, included only in gcov library
 LIBGCOV = _gcov _gcov_merge_add _gcov_merge_single _gcov_merge_delta \
     _gcov_fork _gcov_execl _gcov_execlp _gcov_execle \
-    _gcov_execv _gcov_execvp _gcov_execve \
+    _gcov_execv _gcov_execvp _gcov_execve _gcov_reset _gcov_dump \
     _gcov_interval_profiler _gcov_pow2_profiler _gcov_one_value_profiler \
     _gcov_indirect_call_profiler _gcov_average_profiler _gcov_ior_profiler \
     _gcov_merge_ior
Index: libgcc/libgcov.c
===================================================================
--- libgcc/libgcov.c	(revision 187048)
+++ libgcc/libgcov.c	(working copy)
@@ -50,6 +50,14 @@  void __gcov_init (struct gcov_info *p __attribute_
 void __gcov_flush (void) {}
 #endif
 
+#ifdef L_gcov_reset
+void __gcov_reset (void) {}
+#endif
+
+#ifdef L_gcov_dump
+void __gcov_dump (void) {}
+#endif
+
 #ifdef L_gcov_merge_add
 void __gcov_merge_add (gcov_type *counters  __attribute__ ((unused)),
 		       unsigned n_counters __attribute__ ((unused))) {}
@@ -74,7 +82,7 @@  void __gcov_merge_delta (gcov_type *counters  __at
 #include <sys/stat.h>
 #endif
 
-#ifdef L_gcov
+#if defined(L_gcov) || defined(L_gcov_reset) || defined(L_gcov_dump)
 #include "gcov-io.c"
 
 struct gcov_fn_buffer
@@ -91,6 +99,9 @@  static struct gcov_info *gcov_list;
 /* Size of the longest file name. */
 static size_t gcov_max_filename = 0;
 
+/* Flag when the profile has already been dumped via __gcov_dump().  */
+static int gcov_dump_complete = 0;
+
 /* Make sure path component of the given FILENAME exists, create
    missing directories. FILENAME must be writable.
    Returns zero on success, or -1 if an error occurred.  */
@@ -286,6 +297,11 @@  gcov_exit (void)
   char *gi_filename, *gi_filename_up;
   gcov_unsigned_t crc32 = 0;
 
+  /* Prevent the counters from being dumped a second time on exit when the
+     application already wrote out the profile using __gcov_dump().  */
+  if (gcov_dump_complete)
+    return;
+
   memset (&all_prg, 0, sizeof (all_prg));
   /* Find the totals for this execution.  */
   memset (&this_prg, 0, sizeof (this_prg));
@@ -679,6 +695,37 @@  gcov_exit (void)
     }
 }
 
+/* Reset all counters to zero.  */
+
+static void
+gcov_clear (void)
+{
+  const struct gcov_info *gi_ptr;
+
+  for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
+    {
+      unsigned f_ix;
+
+      for (f_ix = 0; f_ix < gi_ptr->n_functions; f_ix++)
+	{
+	  unsigned t_ix;
+	  const struct gcov_fn_info *gfi_ptr = gi_ptr->functions[f_ix];
+
+	  if (!gfi_ptr || gfi_ptr->key != gi_ptr)
+	    continue;
+	  const struct gcov_ctr_info *ci_ptr = gfi_ptr->ctrs;
+	  for (t_ix = 0; t_ix != GCOV_COUNTERS; t_ix++)
+	    {
+	      if (!gi_ptr->merge[t_ix])
+		continue;
+	      
+	      memset (ci_ptr->values, 0, sizeof (gcov_type) * ci_ptr->num);
+	      ci_ptr++;
+	    }
+	}
+    }
+}
+
 /* Add a new object file onto the bb chain.  Invoked automatically
    when running an object file's global ctors.  */
 
@@ -730,40 +777,48 @@  init_mx_once (void)
 void
 __gcov_flush (void)
 {
-  const struct gcov_info *gi_ptr;
-
   init_mx_once ();
   __gthread_mutex_lock (&__gcov_flush_mx);
 
   gcov_exit ();
-  for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
-    {
-      unsigned f_ix;
+  gcov_clear ();
 
-      for (f_ix = 0; f_ix < gi_ptr->n_functions; f_ix++)
-	{
-	  unsigned t_ix;
-	  const struct gcov_fn_info *gfi_ptr = gi_ptr->functions[f_ix];
-
-	  if (!gfi_ptr || gfi_ptr->key != gi_ptr)
-	    continue;
-	  const struct gcov_ctr_info *ci_ptr = gfi_ptr->ctrs;
-	  for (t_ix = 0; t_ix != GCOV_COUNTERS; t_ix++)
-	    {
-	      if (!gi_ptr->merge[t_ix])
-		continue;
-	      
-	      memset (ci_ptr->values, 0, sizeof (gcov_type) * ci_ptr->num);
-	      ci_ptr++;
-	    }
-	}
-    }
-
   __gthread_mutex_unlock (&__gcov_flush_mx);
 }
 
 #endif /* L_gcov */
 
+#ifdef L_gcov_reset
+
+/* Function that can be called from application to reset counters to zero,
+   in order to collect profile in region of interest.  */
+
+void
+__gcov_reset (void)
+{
+  gcov_clear ();
+  /* Re-enable dumping to support collecting profile in multiple regions
+     of interest.  */
+  gcov_dump_complete = 0;
+}
+
+#endif /* L_gcov_reset */
+
+#ifdef L_gcov_dump
+
+/* Function that can be called from application to write profile collected
+   so far, in order to collect profile in region of interest.  */
+
+void
+__gcov_dump (void)
+{
+  gcov_exit ();
+  /* Prevent profile from being dumped a second time on application exit.  */
+  gcov_dump_complete = 1;
+}
+
+#endif /* L_gcov_dump */
+
 #ifdef L_gcov_merge_add
 /* The profile merging function that just adds the counters.  It is given
    an array COUNTERS of N_COUNTERS old counters and it reads the same number
Index: gcc/doc/gcov.texi
===================================================================
--- gcc/doc/gcov.texi	(revision 187048)
+++ gcc/doc/gcov.texi	(working copy)
@@ -538,6 +538,12 @@  now be calculable at compile time in some instance
 coverage of all the uses of the inline function will be shown for the
 same source lines, the line counts themselves might seem inconsistent.
 
+Long-running applications can use the @code{_gcov_reset} and @code{_gcov_dump}
+facilities to restrict profile collection to the program region of
+interest. Calling @code{_gcov_reset(void)} will clear all profile counters
+to zero, and calling @code{_gcov_dump(void)} will cause the profile information
+collected at that point to be dumped to @file{.gcda} output files.
+
 @c man end
 
 @node Gcov Data Files
Index: gcc/gcov-io.h
===================================================================
--- gcc/gcov-io.h	(revision 187048)
+++ gcc/gcov-io.h	(working copy)
@@ -458,6 +458,12 @@  extern void __gcov_init (struct gcov_info *) ATTRI
 /* Called before fork, to avoid double counting.  */
 extern void __gcov_flush (void) ATTRIBUTE_HIDDEN;
 
+/* Function to reset all counters to 0.  */
+extern void __gcov_reset (void);
+
+/* Function to enable early write of profile information so far.  */
+extern void __gcov_dump (void);
+
 /* The merge function that just sums the counters.  */
 extern void __gcov_merge_add (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;