From: Martin Liska <mliska@suse.cz>
Date: Fri, 31 Jan 2020 12:10:14 +0000 (+0100)
Subject: Make TOPN counter dynamically allocated.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=871e5ada6d53d5eb495cc9f323983f347487c1b2;p=gcc.git

Make TOPN counter dynamically allocated.

gcc/ChangeLog:

	* coverage.c (get_coverage_counts): Skip sanity check for TOP N counters
	as they have variable number of counters.
	* gcov-dump.c (main): Add new option -r.
	(print_usage): Likewise.
	(tag_counters): All new raw format.
	* gcov-io.h (struct gcov_kvp): New.
	(GCOV_TOPN_VALUES): Remove.
	(GCOV_TOPN_VALUES_COUNTERS): Likewise.
	(GCOV_TOPN_MEM_COUNTERS): New.
	(GCOV_TOPN_DISK_COUNTERS): Likewise.
	(GCOV_TOPN_MAXIMUM_TRACKED_VALUES): Likewise.
	* ipa-profile.c (ipa_profile_generate_summary): Use
	GCOV_TOPN_MAXIMUM_TRACKED_VALUES.
	(ipa_profile_write_edge_summary): Likewise.
	(ipa_profile_read_edge_summary): Likewise.
	(ipa_profile): Remove usage of GCOV_TOPN_VALUES.
	* profile.c (sort_hist_values): Sort variable number
	of counters.
	(compute_value_histograms): Special case for TOP N counters
	that have dynamic number of key-value pairs.
	* value-prof.c (dump_histogram_value): Dump variable number
	of key-value pairs.
	(stream_in_histogram_value): Stream in variable number
	of key-value pairs for TOP N counter.
	(get_nth_most_common_value): Deal with variable number
	of key-value pairs.
	(dump_ic_profile): Use GCOV_TOPN_MAXIMUM_TRACKED_VALUES
	for loop iteration.
	(gimple_find_values_to_profile): Set GCOV_TOPN_MEM_COUNTERS
	to n_counters.
	* doc/gcov-dump.texi: Document new -r option.

libgcc/ChangeLog:

	* libgcov-driver.c (prune_topn_counter): Remove.
	(prune_counters): Likewise.
	(merge_one_data): Special case TOP N counters
	as they have variable length.
	(write_top_counters): New.
	(write_one_data): Special case TOP N.
	(dump_one_gcov): Do not prune TOP N counters.
	* libgcov-merge.c (merge_topn_values_set): Remove.
	(__gcov_merge_topn): Use gcov_topn_add_value.
	* libgcov-profiler.c (__gcov_topn_values_profiler_body):
	Likewise here.
	* libgcov.h (gcov_counter_add): New.
	(gcov_counter_set_if_null): Likewise.
	(gcov_topn_add_value): New.
---

diff --git a/gcc/coverage.c b/gcc/coverage.c
index 7d82e44c152..1dcda4353cd 100644
--- a/gcc/coverage.c
+++ b/gcc/coverage.c
@@ -345,8 +345,11 @@ get_coverage_counts (unsigned counter, unsigned cfg_checksum,
 	 can do about it.  */
       return NULL;
     }
-  
-  if (entry->cfg_checksum != cfg_checksum || entry->n_counts != n_counts)
+
+  if (entry->cfg_checksum != cfg_checksum
+      || (counter != GCOV_COUNTER_V_INDIR
+	  && counter != GCOV_COUNTER_V_TOPN
+	  && entry->n_counts != n_counts))
     {
       static int warned = 0;
       bool warning_printed = false;
diff --git a/gcc/doc/gcov-dump.texi b/gcc/doc/gcov-dump.texi
index 776c0d591a4..419df988df4 100644
--- a/gcc/doc/gcov-dump.texi
+++ b/gcc/doc/gcov-dump.texi
@@ -61,6 +61,7 @@ gcov-dump [@option{-v}|@option{--version}]
      [@option{-h}|@option{--help}]
      [@option{-l}|@option{--long}]
      [@option{-p}|@option{--positions}]
+     [@option{-r}|@option{--raw}]
      @var{gcovfiles}
 @c man end
 @end ignore
@@ -80,6 +81,10 @@ Dump content of records.
 @itemx --positions
 Dump positions of records.
 
+@item -r
+@itemx --raw
+Print content records in raw format.
+
 @item -v
 @itemx --version
 Display the @command{gcov-dump} version number (on the standard output),
diff --git a/gcc/gcov-dump.c b/gcc/gcov-dump.c
index bd2ae223ac6..90cbd1ace52 100644
--- a/gcc/gcov-dump.c
+++ b/gcc/gcov-dump.c
@@ -49,6 +49,7 @@ typedef struct tag_format
 
 static int flag_dump_contents = 0;
 static int flag_dump_positions = 0;
+static int flag_dump_raw = 0;
 
 static const struct option options[] =
 {
@@ -95,7 +96,7 @@ main (int argc ATTRIBUTE_UNUSED, char **argv)
 
   diagnostic_initialize (global_dc, 0);
 
-  while ((opt = getopt_long (argc, argv, "hlpvw", options, NULL)) != -1)
+  while ((opt = getopt_long (argc, argv, "hlprvw", options, NULL)) != -1)
     {
       switch (opt)
 	{
@@ -111,6 +112,9 @@ main (int argc ATTRIBUTE_UNUSED, char **argv)
 	case 'p':
 	  flag_dump_positions = 1;
 	  break;
+	case 'r':
+	  flag_dump_raw = 1;
+	  break;
 	default:
 	  fprintf (stderr, "unknown flag `%c'\n", opt);
 	}
@@ -129,6 +133,7 @@ print_usage (void)
   printf ("  -h, --help           Print this help\n");
   printf ("  -l, --long           Dump record contents too\n");
   printf ("  -p, --positions      Dump record positions\n");
+  printf ("  -r, --raw		  Print content records in raw format\n");
   printf ("  -v, --version        Print version number\n");
   printf ("\nFor bug reporting instructions, please see:\n%s.\n",
 	   bug_report_url);
@@ -441,7 +446,12 @@ tag_counters (const char *filename ATTRIBUTE_UNUSED,
 	{
 	  gcov_type count;
 
-	  if (!(ix & 7))
+	  if (flag_dump_raw)
+	    {
+	      if (ix == 0)
+		printf (": ");
+	    }
+	  else if (!(ix & 7))
 	    {
 	      printf ("\n");
 	      print_prefix (filename, depth, gcov_position ());
diff --git a/gcc/gcov-io.h b/gcc/gcov-io.h
index 8cb68aaf42d..940eb7d8561 100644
--- a/gcc/gcov-io.h
+++ b/gcc/gcov-io.h
@@ -170,6 +170,17 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #ifndef GCC_GCOV_IO_H
 #define GCC_GCOV_IO_H
 
+/* GCOV key-value pair linked list type.  */
+
+struct gcov_kvp;
+
+struct gcov_kvp
+{
+  gcov_type value;
+  gcov_type count;
+  struct gcov_kvp *next;
+};
+
 #ifndef IN_LIBGCOV
 /* About the host */
 
@@ -272,11 +283,14 @@ GCOV_COUNTERS
 #define GCOV_N_VALUE_COUNTERS \
   (GCOV_LAST_VALUE_COUNTER - GCOV_FIRST_VALUE_COUNTER + 1)
 
-/* Number of top N value histogram.  */
-#define GCOV_TOPN_VALUES 4
+/* Number of top N counters when being in memory.  */
+#define GCOV_TOPN_MEM_COUNTERS 3
+
+/* Number of top N counters in disk representation.  */
+#define GCOV_TOPN_DISK_COUNTERS 2
 
-/* Total number of single value counters.  */
-#define GCOV_TOPN_VALUES_COUNTERS (2 * GCOV_TOPN_VALUES + 1)
+/* Maximum number of tracked TOP N value profiles.  */
+#define GCOV_TOPN_MAXIMUM_TRACKED_VALUES 32
 
 /* Convert a counter index to a tag.  */
 #define GCOV_TAG_FOR_COUNTER(COUNT)				\
diff --git a/gcc/ipa-profile.c b/gcc/ipa-profile.c
index 9fbfa90e538..43e9b6bb4db 100644
--- a/gcc/ipa-profile.c
+++ b/gcc/ipa-profile.c
@@ -295,7 +295,8 @@ ipa_profile_generate_summary (void)
 		      speculative_call_summary *csum
 			= call_sums->get_create (e);
 
-		      for (unsigned j = 0; j < GCOV_TOPN_VALUES; j++)
+		      for (unsigned j = 0; j < GCOV_TOPN_MAXIMUM_TRACKED_VALUES;
+			   j++)
 			{
 			  if (!get_nth_most_common_value (NULL, "indirect call",
 							  h, &val, &count, &all,
@@ -342,7 +343,7 @@ ipa_profile_write_edge_summary (lto_simple_output_block *ob,
 
   len = csum->speculative_call_targets.length ();
 
-  gcc_assert (len <= GCOV_TOPN_VALUES);
+  gcc_assert (len <= GCOV_TOPN_MAXIMUM_TRACKED_VALUES);
 
   streamer_write_hwi_stream (ob->main_stream, len);
 
@@ -448,8 +449,7 @@ ipa_profile_read_edge_summary (class lto_input_block *ib, cgraph_edge *edge)
   unsigned i, len;
 
   len = streamer_read_hwi (ib);
-  gcc_assert (len <= GCOV_TOPN_VALUES);
-
+  gcc_assert (len <= GCOV_TOPN_MAXIMUM_TRACKED_VALUES);
   speculative_call_summary *csum = call_sums->get_create (edge);
 
   for (i = 0; i < len; i++)
@@ -885,8 +885,7 @@ ipa_profile (void)
 				   item.target_probability
 				     / (float) REG_BR_PROB_BASE);
 			}
-		      if (item.target_probability
-		 	  < REG_BR_PROB_BASE / GCOV_TOPN_VALUES / 2)
+		      if (item.target_probability < REG_BR_PROB_BASE / 2)
 			{
 			  nuseless++;
 			  if (dump_file)
diff --git a/gcc/profile.c b/gcc/profile.c
index cd754c4c66a..bd1eac123df 100644
--- a/gcc/profile.c
+++ b/gcc/profile.c
@@ -765,26 +765,22 @@ compute_branch_probabilities (unsigned cfg_checksum, unsigned lineno_checksum)
 static void
 sort_hist_values (histogram_value hist)
 {
-  /* counters[2] equal to -1 means that all counters are invalidated.  */
-  if (hist->hvalue.counters[2] == -1)
-    return;
-
   gcc_assert (hist->type == HIST_TYPE_TOPN_VALUES
 	      || hist->type == HIST_TYPE_INDIR_CALL);
 
-  gcc_assert (hist->n_counters == GCOV_TOPN_VALUES_COUNTERS);
-
+  int counters = hist->hvalue.counters[1];
+  for (int i = 0; i < counters - 1; i++)
   /* Hist value is organized as:
-     [total_executions, value1, counter1, ..., value4, counter4]
+     [total_executions, N, counter1, ..., valueN, counterN]
      Use decrease bubble sort to rearrange it.  The sort starts from <value1,
      counter1> and compares counter first.  If counter is same, compares the
      value, exchange it if small to keep stable.  */
-  for (unsigned i = 0; i < GCOV_TOPN_VALUES - 1; i++)
+
     {
       bool swapped = false;
-      for (unsigned j = 0; j < GCOV_TOPN_VALUES - 1 - i; j++)
+      for (int j = 0; j < counters - 1 - i; j++)
 	{
-	  gcov_type *p = &hist->hvalue.counters[2 * j + 1];
+	  gcov_type *p = &hist->hvalue.counters[2 * j + 2];
 	  if (p[1] < p[3] || (p[1] == p[3] && p[0] < p[2]))
 	    {
 	      std::swap (p[0], p[2]);
@@ -847,31 +843,43 @@ compute_value_histograms (histogram_values values, unsigned cfg_checksum,
       gimple *stmt = hist->hvalue.stmt;
 
       t = (int) hist->type;
+      bool topn_p = (hist->type == HIST_TYPE_TOPN_VALUES
+		     || hist->type == HIST_TYPE_INDIR_CALL);
 
-      aact_count = act_count[t];
-
-      if (act_count[t])
-        act_count[t] += hist->n_counters;
-
-      gimple_add_histogram_value (cfun, stmt, hist);
-      hist->hvalue.counters =  XNEWVEC (gcov_type, hist->n_counters);
-      for (j = 0; j < hist->n_counters; j++)
-        if (aact_count)
-          hist->hvalue.counters[j] = aact_count[j];
-        else
-          hist->hvalue.counters[j] = 0;
-
-      if (hist->type == HIST_TYPE_TOPN_VALUES
-	  || hist->type == HIST_TYPE_INDIR_CALL)
+      /* TOP N counter uses variable number of counters.  */
+      if (topn_p)
 	{
-	  /* Each count value is multiplied by GCOV_TOPN_VALUES.  */
-	  if (hist->hvalue.counters[2] != -1)
-	    for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
-	      hist->hvalue.counters[2 * i + 2]
-		= RDIV (hist->hvalue.counters[2 * i + 2], GCOV_TOPN_VALUES);
-
+	  unsigned total_size;
+	  if (act_count[t])
+	    total_size = 2 + 2 * act_count[t][1];
+	  else
+	    total_size = 2;
+	  gimple_add_histogram_value (cfun, stmt, hist);
+	  hist->n_counters = total_size;
+	  hist->hvalue.counters = XNEWVEC (gcov_type, hist->n_counters);
+	  for (j = 0; j < hist->n_counters; j++)
+	    if (act_count[t])
+	      hist->hvalue.counters[j] = act_count[t][j];
+	    else
+	      hist->hvalue.counters[j] = 0;
+	  act_count[t] += hist->n_counters;
 	  sort_hist_values (hist);
 	}
+      else
+	{
+	  aact_count = act_count[t];
+
+	  if (act_count[t])
+	    act_count[t] += hist->n_counters;
+
+	  gimple_add_histogram_value (cfun, stmt, hist);
+	  hist->hvalue.counters = XNEWVEC (gcov_type, hist->n_counters);
+	  for (j = 0; j < hist->n_counters; j++)
+	    if (aact_count)
+	      hist->hvalue.counters[j] = aact_count[j];
+	    else
+	      hist->hvalue.counters[j] = 0;
+	}
 
       /* Time profiler counter is not related to any statement,
          so that we have to read the counter and set the value to
diff --git a/gcc/value-prof.c b/gcc/value-prof.c
index 45677be46b1..ea1b1a8f98f 100644
--- a/gcc/value-prof.c
+++ b/gcc/value-prof.c
@@ -265,16 +265,15 @@ dump_histogram_value (FILE *dump_file, histogram_value hist)
 		    ? "Top N value counter" : "Indirect call counter"));
 	  if (hist->hvalue.counters)
 	    {
-	      fprintf (dump_file, " all: %" PRId64 "%s, values: ",
-		       (int64_t) abs_hwi (hist->hvalue.counters[0]),
-		       hist->hvalue.counters[0] < 0
-		       ? " (values missing)": "");
-	      for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
+	      unsigned count = hist->hvalue.counters[1];
+	      fprintf (dump_file, " all: %" PRId64 ", %" PRId64 " values: ",
+		       (int64_t) hist->hvalue.counters[0], (int64_t) count);
+	      for (unsigned i = 0; i < count; i++)
 		{
 		  fprintf (dump_file, "[%" PRId64 ":%" PRId64 "]",
-			   (int64_t) hist->hvalue.counters[2 * i + 1],
-			   (int64_t) hist->hvalue.counters[2 * i + 2]);
-		  if (i != GCOV_TOPN_VALUES - 1)
+			   (int64_t) hist->hvalue.counters[2 * i + 2],
+			   (int64_t) hist->hvalue.counters[2 * i + 3]);
+		  if (i != count - 1)
 		    fprintf (dump_file, ", ");
 		}
 	      fprintf (dump_file, ".\n");
@@ -377,7 +376,6 @@ stream_in_histogram_value (class lto_input_block *ib, gimple *stmt)
 
 	case HIST_TYPE_TOPN_VALUES:
 	case HIST_TYPE_INDIR_CALL:
-	  ncounters = GCOV_TOPN_VALUES_COUNTERS;
 	  break;
 
 	case HIST_TYPE_IOR:
@@ -388,12 +386,31 @@ stream_in_histogram_value (class lto_input_block *ib, gimple *stmt)
 	default:
 	  gcc_unreachable ();
 	}
-      new_val->hvalue.counters = XNEWVAR (gcov_type,
-					  sizeof (*new_val->hvalue.counters)
-					  * ncounters);
-      new_val->n_counters = ncounters;
-      for (i = 0; i < ncounters; i++)
-	new_val->hvalue.counters[i] = streamer_read_gcov_count (ib);
+
+      /* TOP N counters have variable number of counters.  */
+      if (type == HIST_TYPE_INDIR_CALL || type == HIST_TYPE_TOPN_VALUES)
+	{
+	  gcov_type total = streamer_read_gcov_count (ib);
+	  gcov_type ncounters = streamer_read_gcov_count (ib);
+	  new_val->hvalue.counters = XNEWVAR (gcov_type,
+					      sizeof (*new_val->hvalue.counters)
+					      * (2 + 2 * ncounters));
+	  new_val->hvalue.counters[0] = total;
+	  new_val->hvalue.counters[1] = ncounters;
+	  new_val->n_counters = 2 + 2 * ncounters;
+	  for (i = 0; i < 2 * ncounters; i++)
+	    new_val->hvalue.counters[2 + i] = streamer_read_gcov_count (ib);
+	}
+      else
+	{
+	  new_val->hvalue.counters = XNEWVAR (gcov_type,
+					      sizeof (*new_val->hvalue.counters)
+					      * ncounters);
+	  new_val->n_counters = ncounters;
+	  for (i = 0; i < ncounters; i++)
+	    new_val->hvalue.counters[i] = streamer_read_gcov_count (ib);
+	}
+
       if (!next_p)
 	gimple_add_histogram_value (cfun, stmt, new_val);
       else
@@ -738,15 +755,17 @@ get_nth_most_common_value (gimple *stmt, const char *counter_type,
 			   histogram_value hist, gcov_type *value,
 			   gcov_type *count, gcov_type *all, unsigned n)
 {
-  gcc_assert (n < GCOV_TOPN_VALUES);
+  unsigned counters = hist->hvalue.counters[1];
+  if (n >= counters)
+    return false;
 
   *count = 0;
   *value = 0;
 
   gcov_type read_all = abs_hwi (hist->hvalue.counters[0]);
 
-  gcov_type v = hist->hvalue.counters[2 * n + 1];
-  gcov_type c = hist->hvalue.counters[2 * n + 2];
+  gcov_type v = hist->hvalue.counters[2 * n + 2];
+  gcov_type c = hist->hvalue.counters[2 * n + 3];
 
   if (hist->hvalue.counters[0] < 0
       && (flag_profile_reproducible == PROFILE_REPRODUCIBILITY_PARALLEL_RUNS
@@ -1433,7 +1452,7 @@ dump_ic_profile (gimple_stmt_iterator *gsi)
   count = 0;
   all = histogram->hvalue.counters[0];
 
-  for (unsigned j = 0; j < GCOV_TOPN_VALUES; j++)
+  for (unsigned j = 0; j < GCOV_TOPN_MAXIMUM_TRACKED_VALUES; j++)
     {
       if (!get_nth_most_common_value (NULL, "indirect call", histogram, &val,
 				      &count, &all, j))
@@ -1902,7 +1921,7 @@ gimple_find_values_to_profile (histogram_values *values)
 
 	case HIST_TYPE_TOPN_VALUES:
 	case HIST_TYPE_INDIR_CALL:
-	  hist->n_counters = GCOV_TOPN_VALUES_COUNTERS;
+	  hist->n_counters = GCOV_TOPN_MEM_COUNTERS;
 	  break;
 
         case HIST_TYPE_TIME_PROFILE:
diff --git a/libgcc/libgcov-driver.c b/libgcc/libgcov-driver.c
index fb320738e1e..8348d9f33ec 100644
--- a/libgcc/libgcov-driver.c
+++ b/libgcc/libgcov-driver.c
@@ -213,51 +213,6 @@ static struct gcov_fn_buffer *fn_buffer;
 /* Including system dependent components. */
 #include "libgcov-driver-system.c"
 
-/* Prune TOP N value COUNTERS.  It's needed in order to preserve
-   reproducibility of builds.  */
-
-static void
-prune_topn_counter (gcov_type *counters, gcov_type all)
-{
-  for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
-    if (counters[2 * i + 1] < all)
-      {
-	counters[2 * i] = 0;
-	counters[2 * i + 1] = 0;
-      }
-}
-
-/* Prune counters so that they are ready to store or merge.  */
-
-static void
-prune_counters (struct gcov_info *gi)
-{
-  for (unsigned i = 0; i < gi->n_functions; i++)
-    {
-      const struct gcov_fn_info *gfi = gi->functions[i];
-      const struct gcov_ctr_info *ci = gfi->ctrs;
-
-      for (unsigned j = 0; j < GCOV_COUNTERS; j++)
-	{
-	  if (gi->merge[j] == NULL)
-	    continue;
-
-	  if (gi->merge[j] == __gcov_merge_topn)
-	    {
-	      gcc_assert (!(ci->num % GCOV_TOPN_VALUES_COUNTERS));
-	      for (unsigned k = 0; k < (ci->num / GCOV_TOPN_VALUES_COUNTERS);
-		   k++)
-		{
-		  gcov_type *counters
-		    = ci->values + (k * GCOV_TOPN_VALUES_COUNTERS);
-		  prune_topn_counter (counters + 1, *counters);
-		}
-	    }
-	  ci++;
-	}
-    }
-}
-
 /* This function merges counters in GI_PTR to an existing gcda file.
    Return 0 on success.
    Return -1 on error. In this case, caller will goto read_fatal.  */
@@ -346,16 +301,18 @@ merge_one_data (const char *filename,
           if (!merge)
             continue;
 
-          tag = gcov_read_unsigned ();
-          length = gcov_read_unsigned ();
-          if (tag != GCOV_TAG_FOR_COUNTER (t_ix)
-              || length != GCOV_TAG_COUNTER_LENGTH (ci_ptr->num))
-            goto read_mismatch;
-          (*merge) (ci_ptr->values, ci_ptr->num);
-          ci_ptr++;
-        }
+	  tag = gcov_read_unsigned ();
+	  length = gcov_read_unsigned ();
+	  if (tag != GCOV_TAG_FOR_COUNTER (t_ix)
+	      || (length != GCOV_TAG_COUNTER_LENGTH (ci_ptr->num)
+		  && t_ix != GCOV_COUNTER_V_TOPN
+		  && t_ix != GCOV_COUNTER_V_INDIR))
+	    goto read_mismatch;
+	  (*merge) (ci_ptr->values, ci_ptr->num);
+	  ci_ptr++;
+	}
       if ((error = gcov_is_error ()))
-        goto read_error;
+	goto read_error;
     }
 
   if (tag)
@@ -374,6 +331,37 @@ read_error:
   return -1;
 }
 
+/* Store all TOP N counters where each has a dynamic length.  */
+
+static void
+write_top_counters (const struct gcov_ctr_info *ci_ptr,
+		    unsigned t_ix,
+		    gcov_unsigned_t n_counts)
+{
+  unsigned counters = n_counts / GCOV_TOPN_MEM_COUNTERS;
+  gcc_assert (n_counts % GCOV_TOPN_MEM_COUNTERS == 0);
+  unsigned pair_total = 0;
+  for (unsigned i = 0; i < counters; i++)
+    pair_total += ci_ptr->values[GCOV_TOPN_MEM_COUNTERS * i + 1];
+  unsigned disk_size = GCOV_TOPN_DISK_COUNTERS * counters + 2 * pair_total;
+  gcov_write_tag_length (GCOV_TAG_FOR_COUNTER (t_ix),
+			 GCOV_TAG_COUNTER_LENGTH (disk_size));
+
+  for (unsigned i = 0; i < counters; i++)
+    {
+      gcov_type pair_count = ci_ptr->values[GCOV_TOPN_MEM_COUNTERS * i + 1];
+      gcov_write_counter (ci_ptr->values[GCOV_TOPN_MEM_COUNTERS * i]);
+      gcov_write_counter (pair_count);
+      for (struct gcov_kvp *node
+	   = (struct gcov_kvp *)ci_ptr->values[GCOV_TOPN_MEM_COUNTERS * i + 2];
+	   node != NULL; node = node->next)
+	{
+	  gcov_write_counter (node->value);
+	  gcov_write_counter (node->count);
+	}
+    }
+}
+
 /* Write counters in GI_PTR and the summary in PRG to a gcda file. In
    the case of appending to an existing file, SUMMARY_POS will be non-zero.
    We will write the file starting from SUMMAY_POS.  */
@@ -433,11 +421,18 @@ write_one_data (const struct gcov_info *gi_ptr,
             continue;
 
           n_counts = ci_ptr->num;
-          gcov_write_tag_length (GCOV_TAG_FOR_COUNTER (t_ix),
-                                 GCOV_TAG_COUNTER_LENGTH (n_counts));
-          c_ptr = ci_ptr->values;
-          while (n_counts--)
-            gcov_write_counter (*c_ptr++);
+
+	  if (gi_ptr->merge[t_ix] == __gcov_merge_topn)
+	    write_top_counters (ci_ptr, t_ix, n_counts);
+	  else
+	    {
+	      gcov_write_tag_length (GCOV_TAG_FOR_COUNTER (t_ix),
+				     GCOV_TAG_COUNTER_LENGTH (n_counts));
+	      c_ptr = ci_ptr->values;
+	      while (n_counts--)
+		gcov_write_counter (*c_ptr++);
+	    }
+
           ci_ptr++;
         }
       if (buffered)
@@ -476,9 +471,6 @@ dump_one_gcov (struct gcov_info *gi_ptr, struct gcov_filename *gf,
   gcov_unsigned_t tag;
   fn_buffer = 0;
 
-  /* Prune current counters before we merge them.  */
-  prune_counters (gi_ptr);
-
   error = gcov_exit_open_gcda_file (gi_ptr, gf);
   if (error == -1)
     return;
diff --git a/libgcc/libgcov-merge.c b/libgcc/libgcov-merge.c
index c0785b0bf10..1acdaa0403e 100644
--- a/libgcc/libgcov-merge.c
+++ b/libgcc/libgcov-merge.c
@@ -86,86 +86,6 @@ __gcov_merge_time_profile (gcov_type *counters, unsigned n_counters)
 
 #ifdef L_gcov_merge_topn
 
-/* To merging of TOPN profiles.
-   counters[0] is the number of executions
-   for i in 0 ... TOPN-1
-     counters[2 * i + 1] is target
-     counters[2 * i + 2] is corresponding hitrate counter.
-
-   Because we prune counters only those with probability >= 1/TOPN are
-   present now.
-
-   We use sign of counters[0] to track whether the number of different
-   targets exceeds TOPN.  */
-
-static void
-merge_topn_values_set (gcov_type *counters)
-{
-  /* First value is number of total executions of the profiler.  */
-  gcov_type all = gcov_get_counter ();
-  gcov_type *total = &counters[0];
-  ++counters;
-
-  /* Negative value means that counter is missing some of values.  */
-  if (all < 0)
-    *total = -(*total);
-
-  *total += all;
-
-  /* Read all part values.  */
-  gcov_type read_counters[2 * GCOV_TOPN_VALUES];
-  for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
-    {
-      read_counters[2 * i] = gcov_get_counter_target ();
-      read_counters[2 * i + 1] = gcov_get_counter_ignore_scaling (-1);
-    }
-
-  for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
-    {
-      if (read_counters[2 * i + 1] == 0)
-	continue;
-
-      unsigned j;
-      int slot = 0;
-
-      for (j = 0; j < GCOV_TOPN_VALUES; j++)
-	{
-	  if (counters[2 * j] == read_counters[2 * i])
-	    {
-	      counters[2 * j + 1] += read_counters[2 * i + 1];
-	      break;
-	    }
-	  else if (counters[2 * j + 1] < counters[2 * slot + 1])
-	    slot = j;
-	}
-
-      if (j == GCOV_TOPN_VALUES)
-	{
-	  gcov_type slot_count = counters[2 * slot + 1];
-	  /* We found an empty slot.  */
-	  if (slot_count == 0)
-	    {
-	      /* If we found empty slot, add the value.  */
-	      counters[2 * slot] = read_counters[2 * i];
-	      counters[2 * slot + 1] = read_counters[2 * i + 1];
-	    }
-	  else
-	    {
-	      /* Here we are loosing some values.  */
-	      if (*total >= 0)
-		*total = -(*total);
-	      if (read_counters[2 * i + 1] > slot_count)
-		{
-		  counters[2 * slot] = read_counters[2 * i];
-		  counters[2 * slot + 1] = read_counters[2 * i + 1];
-		}
-	      else
-		counters[2 * slot + 1] -= read_counters[2 * i + 1];
-	    }
-	}
-    }
-}
-
 /* The profile merging function for choosing the most common value.
    It is given an array COUNTERS of N_COUNTERS old counters and it
    reads the same number of counters from the gcov file.  The counters
@@ -175,13 +95,30 @@ merge_topn_values_set (gcov_type *counters)
    -- the stored candidate on the most common value of the measured entity
    -- counter
    */
+
 void
 __gcov_merge_topn (gcov_type *counters, unsigned n_counters)
 {
-  gcc_assert (!(n_counters % GCOV_TOPN_VALUES_COUNTERS));
+  gcc_assert (!(n_counters % GCOV_TOPN_MEM_COUNTERS));
 
-  for (unsigned i = 0; i < (n_counters / GCOV_TOPN_VALUES_COUNTERS); i++)
-    merge_topn_values_set (counters + (i * GCOV_TOPN_VALUES_COUNTERS));
+  for (unsigned i = 0; i < (n_counters / GCOV_TOPN_MEM_COUNTERS); i++)
+    {
+      /* First value is number of total executions of the profiler.  */
+      gcov_type all = gcov_get_counter_ignore_scaling (-1);
+      gcov_type n = gcov_get_counter_ignore_scaling (-1);
+
+      counters[GCOV_TOPN_MEM_COUNTERS * i] += all;
+
+      for (unsigned j = 0; j < n; j++)
+	{
+	  gcov_type value = gcov_get_counter_target ();
+	  gcov_type count = gcov_get_counter_ignore_scaling (-1);
+
+	  // TODO: we should use atomic here
+	  gcov_topn_add_value (counters + GCOV_TOPN_MEM_COUNTERS * i, value,
+			       count, 0, 0);
+	}
+    }
 }
 #endif /* L_gcov_merge_topn */
 
diff --git a/libgcc/libgcov-profiler.c b/libgcc/libgcov-profiler.c
index 6043ac4c7a1..7b171382a07 100644
--- a/libgcc/libgcov-profiler.c
+++ b/libgcc/libgcov-profiler.c
@@ -105,51 +105,13 @@ __gcov_pow2_profiler_atomic (gcov_type *counters, gcov_type value)
 }
 #endif
 
-
 /* Tries to determine N most commons value among its inputs.  */
 
 static inline void
 __gcov_topn_values_profiler_body (gcov_type *counters, gcov_type value,
 				  int use_atomic)
 {
-  if (use_atomic)
-    __atomic_fetch_add (&counters[0], 1, __ATOMIC_RELAXED);
-  else
-    counters[0]++;
-
-  ++counters;
-
-  /* First try to find an existing value.  */
-  int empty_counter = -1;
-
-  for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
-    if (value == counters[2 * i])
-      {
-	if (use_atomic)
-	  __atomic_fetch_add (&counters[2 * i + 1], GCOV_TOPN_VALUES,
-			      __ATOMIC_RELAXED);
-	else
-	  counters[2 * i + 1] += GCOV_TOPN_VALUES;
-	return;
-      }
-    else if (counters[2 * i + 1] <= 0)
-      empty_counter = i;
-
-  /* Find an empty slot for a new value.  */
-  if (empty_counter != -1)
-    {
-      counters[2 * empty_counter] = value;
-      counters[2 * empty_counter + 1] = GCOV_TOPN_VALUES;
-      return;
-    }
-
-  /* We haven't found an empty slot, then decrement all
-     counter values by one.  */
-  for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
-    if (use_atomic)
-      __atomic_fetch_sub (&counters[2 * i + 1], 1, __ATOMIC_RELAXED);
-    else
-      counters[2 * i + 1]--;
+  gcov_topn_add_value (counters, value, 1, use_atomic, 1);
 }
 
 #ifdef L_gcov_topn_values_profiler
diff --git a/libgcc/libgcov.h b/libgcc/libgcov.h
index b248690086e..bc38f4dd804 100644
--- a/libgcc/libgcov.h
+++ b/libgcc/libgcov.h
@@ -373,6 +373,93 @@ gcov_get_counter_target (void)
 #endif
 }
 
+/* Add VALUE to *COUNTER and make it with atomic operation
+   if USE_ATOMIC is true.  */
+
+static inline void
+gcov_counter_add (gcov_type *counter, gcov_type value, int use_atomic)
+{
+  if (use_atomic)
+    __atomic_fetch_add (counter, value, __ATOMIC_RELAXED);
+  else
+    *counter += value;
+}
+
+/* Set NODE to memory location COUNTER and make it with atomic operation
+   if USE_ATOMIC is true.  */
+
+static inline int
+gcov_counter_set_if_null (gcov_type *counter, struct gcov_kvp *node,
+			  int use_atomic)
+{
+  if (use_atomic)
+    return !__sync_val_compare_and_swap (counter, NULL, (intptr_t)node);
+  else
+    {
+      *counter = (intptr_t)node;
+      return 1;
+    }
+}
+
+/* Add key value pair VALUE:COUNT to a top N COUNTERS.  When INCREMENT_TOTAL
+   is true, add COUNT to total of the TOP counter.  If USE_ATOMIC is true,
+   do it in atomic way.  */
+
+static inline void
+gcov_topn_add_value (gcov_type *counters, gcov_type value, gcov_type count,
+		     int use_atomic, int increment_total)
+{
+  if (increment_total)
+    gcov_counter_add (&counters[0], 1, use_atomic);
+
+  struct gcov_kvp *prev_node = NULL;
+  struct gcov_kvp *minimal_node = NULL;
+  struct gcov_kvp *current_node  = (struct gcov_kvp *)counters[2];
+
+  while (current_node)
+    {
+      if (current_node->value == value)
+	{
+	  gcov_counter_add (&current_node->count, count, use_atomic);
+	  return;
+	}
+
+      if (minimal_node == NULL
+	  || current_node->count < minimal_node->count)
+	minimal_node = current_node;
+
+      prev_node = current_node;
+      current_node = current_node->next;
+    }
+
+  if (counters[1] == GCOV_TOPN_MAXIMUM_TRACKED_VALUES)
+    {
+      if (--minimal_node->count < count)
+	{
+	  minimal_node->value = value;
+	  minimal_node->count = count;
+	}
+    }
+  else
+    {
+      struct gcov_kvp *new_node
+	= (struct gcov_kvp *)xmalloc (sizeof (struct gcov_kvp));
+      new_node->value = value;
+      new_node->count = count;
+
+      int success = 0;
+      if (!counters[2])
+	success = gcov_counter_set_if_null (&counters[2], new_node, use_atomic);
+      else if (prev_node && !prev_node->next)
+	success = gcov_counter_set_if_null ((gcov_type *)&prev_node->next,
+					    new_node, use_atomic);
+
+      /* Increment number of nodes.  */
+      if (success)
+	gcov_counter_add (&counters[1], 1, use_atomic);
+    }
+}
+
 #endif /* !inhibit_libc */
 
 #endif /* GCC_LIBGCOV_H */