Implement N disk counters for single value and indirect call counters.

2019-06-10  Martin Liska  <mliska@suse.cz>

	* gcov-io.h (GCOV_DISK_SINGLE_VALUES): New.
	(GCOV_SINGLE_VALUE_COUNTERS): Likewise.
	* ipa-profile.c (ipa_profile_generate_summary):
	Use get_most_common_single_value.
	* tree-profile.c (gimple_init_gcov_profiler):
	Instrument with __gcov_one_value_profiler_v2
	and __gcov_indirect_call_profiler_v4.
	* value-prof.c (dump_histogram_value):
	Print all values for HIST_TYPE_SINGLE_VALUE.
	(stream_out_histogram_value): Update assert for
	N values.
	(stream_in_histogram_value): Set number of
	counters for HIST_TYPE_SINGLE_VALUE.
	(get_most_common_single_value): New.
	(gimple_divmod_fixed_value_transform):
	Use get_most_common_single_value.
	(gimple_ic_transform): Likewise.
	(gimple_stringops_transform): Likewise.
	(gimple_find_values_to_profile): Set number
	of counters for HIST_TYPE_SINGLE_VALUE.
	* value-prof.h (get_most_common_single_value):
	New.
2019-06-10  Martin Liska  <mliska@suse.cz>

	* Makefile.in: Add __gcov_one_value_profiler_v2,
	__gcov_one_value_profiler_v2_atomic and
	__gcov_indirect_call_profiler_v4.
	* libgcov-merge.c (__gcov_merge_single): Change
	function signature.
	(merge_single_value_set): New.
	* libgcov-profiler.c (__gcov_one_value_profiler_body):
	Update functionality.
	(__gcov_one_value_profiler): Remove.
	(__gcov_one_value_profiler_v2): ... this.
	(__gcov_one_value_profiler_atomic): Rename to ...
	(__gcov_one_value_profiler_v2_atomic): this.
	(__gcov_indirect_call_profiler_v3): Rename to ...
	(__gcov_indirect_call_profiler_v4): ... this.
	* libgcov.h (__gcov_one_value_profiler): Remove.
	(__gcov_one_value_profiler_atomic): Remove.
	(__gcov_one_value_profiler_v2_atomic): New.
	(__gcov_indirect_call_profiler_v3): Remove.
	(__gcov_one_value_profiler_v2): New.
	(__gcov_indirect_call_profiler_v4): New.
	(gcov_get_counter_ignore_scaling): New function.

From-SVN: r272106

11 files changed, 249 insertions, 116 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9fc63c540ec..9f1a365ed2e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,30 @@
 2019-06-10  Martin Liska  <mliska@suse.cz>
 
+	* gcov-io.h (GCOV_DISK_SINGLE_VALUES): New.
+	(GCOV_SINGLE_VALUE_COUNTERS): Likewise.
+	* ipa-profile.c (ipa_profile_generate_summary):
+	Use get_most_common_single_value.
+	* tree-profile.c (gimple_init_gcov_profiler):
+	Instrument with __gcov_one_value_profiler_v2
+	and __gcov_indirect_call_profiler_v4.
+	* value-prof.c (dump_histogram_value):
+	Print all values for HIST_TYPE_SINGLE_VALUE.
+	(stream_out_histogram_value): Update assert for
+	N values.
+	(stream_in_histogram_value): Set number of
+	counters for HIST_TYPE_SINGLE_VALUE.
+	(get_most_common_single_value): New.
+	(gimple_divmod_fixed_value_transform):
+	Use get_most_common_single_value.
+	(gimple_ic_transform): Likewise.
+	(gimple_stringops_transform): Likewise.
+	(gimple_find_values_to_profile): Set number
+	of counters for HIST_TYPE_SINGLE_VALUE.
+	* value-prof.h (get_most_common_single_value):
+	New.
+
+2019-06-10  Martin Liska  <mliska@suse.cz>
+
 	* hash-map.h: Pass default value to hash_table ctor.
 	* hash-table.h: Add default value to call of a ctor.
 
diff --git a/gcc/gcov-io.h b/gcc/gcov-io.h
index 69c9a73dba8..0f2905c17ec 100644
--- a/gcc/gcov-io.h
+++ b/gcc/gcov-io.h
@@ -266,6 +266,13 @@ GCOV_COUNTERS
 #define GCOV_N_VALUE_COUNTERS \
   (GCOV_LAST_VALUE_COUNTER - GCOV_FIRST_VALUE_COUNTER + 1)
 
+/* Number of single value histogram values that live
+   on disk representation.  */
+#define GCOV_DISK_SINGLE_VALUES 4
+
+/* Total number of single value counters.  */
+#define GCOV_SINGLE_VALUE_COUNTERS (2 * GCOV_DISK_SINGLE_VALUES + 1)
+
 /* Convert a counter index to a tag.  */
 #define GCOV_TAG_FOR_COUNTER(COUNT)				\
 	(GCOV_TAG_COUNTER_BASE + ((gcov_unsigned_t)(COUNT) << 17))
diff --git a/gcc/ipa-profile.c b/gcc/ipa-profile.c
index de9563d808c..c80ea7a9b95 100644
--- a/gcc/ipa-profile.c
+++ b/gcc/ipa-profile.c
@@ -191,17 +191,17 @@ ipa_profile_generate_summary (void)
 		     takes away bad histograms.  */
 		  if (h)
 		    {
-		      /* counter 0 is target, counter 1 is number of execution we called target,
-			 counter 2 is total number of executions.  */
-		      if (h->hvalue.counters[2])
+		      gcov_type val, count, all;
+		      if (get_most_common_single_value (NULL, "indirect call",
+							h, &val, &count, &all))
 			{
 			  struct cgraph_edge * e = node->get_edge (stmt);
 			  if (e && !e->indirect_unknown_callee)
 			    continue;
-			  e->indirect_info->common_target_id
-			    = h->hvalue.counters [0];
+
+			  e->indirect_info->common_target_id = val;
 			  e->indirect_info->common_target_probability
-			    = GCOV_COMPUTE_SCALE (h->hvalue.counters [1], h->hvalue.counters [2]);
+			    = GCOV_COMPUTE_SCALE (count, all);
 			  if (e->indirect_info->common_target_probability > REG_BR_PROB_BASE)
 			    {
 			      if (dump_file)
diff --git a/gcc/tree-profile.c b/gcc/tree-profile.c
index f2cf4047579..5ca4c3e80b6 100644
--- a/gcc/tree-profile.c
+++ b/gcc/tree-profile.c
@@ -165,10 +165,10 @@ gimple_init_gcov_profiler (void)
 	      = build_function_type_list (void_type_node,
 					  gcov_type_ptr, gcov_type_node,
 					  NULL_TREE);
-      fn_name = concat ("__gcov_one_value_profiler", fn_suffix, NULL);
+      fn_name = concat ("__gcov_one_value_profiler_v2", fn_suffix, NULL);
       tree_one_value_profiler_fn = build_fn_decl (fn_name,
 						  one_value_profiler_fn_type);
-      free (CONST_CAST (char *, fn_name));
+
       TREE_NOTHROW (tree_one_value_profiler_fn) = 1;
       DECL_ATTRIBUTES (tree_one_value_profiler_fn)
 	= tree_cons (get_identifier ("leaf"), NULL,
@@ -182,7 +182,7 @@ gimple_init_gcov_profiler (void)
 					  gcov_type_node,
 					  ptr_type_node,
 					  NULL_TREE);
-      profiler_fn_name = "__gcov_indirect_call_profiler_v3";
+      profiler_fn_name = "__gcov_indirect_call_profiler_v4";
 
       tree_indirect_call_profiler_fn
 	      = build_fn_decl (profiler_fn_name, ic_profiler_fn_type);
diff --git a/gcc/value-prof.c b/gcc/value-prof.c
index 1e14e532070..b95bf85270b 100644
--- a/gcc/value-prof.c
+++ b/gcc/value-prof.c
@@ -259,15 +259,22 @@ dump_histogram_value (FILE *dump_file, histogram_value hist)
       break;
 
     case HIST_TYPE_SINGLE_VALUE:
-      fprintf (dump_file, "Single value ");
+    case HIST_TYPE_INDIR_CALL:
+      fprintf (dump_file,
+	       (hist->type == HIST_TYPE_SINGLE_VALUE
+		? "Single value counter " : "Indirect call counter"));
       if (hist->hvalue.counters)
 	{
-	   fprintf (dump_file, "value:%" PRId64
-		    " match:%" PRId64
-		    " wrong:%" PRId64,
-		    (int64_t) hist->hvalue.counters[0],
-		    (int64_t) hist->hvalue.counters[1],
-		    (int64_t) hist->hvalue.counters[2]);
+	  fprintf (dump_file, "all: %" PRId64 ", values: ",
+		   (int64_t) hist->hvalue.counters[0]);
+	  for (unsigned i = 0; i < GCOV_DISK_SINGLE_VALUES; 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_DISK_SINGLE_VALUES - 1)
+		fprintf (dump_file, ", ");
+	    }
 	}
       fprintf (dump_file, ".\n");
       break;
@@ -294,19 +301,6 @@ dump_histogram_value (FILE *dump_file, histogram_value hist)
       fprintf (dump_file, ".\n");
       break;
 
-    case HIST_TYPE_INDIR_CALL:
-      fprintf (dump_file, "Indirect call ");
-      if (hist->hvalue.counters)
-	{
-	   fprintf (dump_file, "value:%" PRId64
-		    " match:%" PRId64
-		    " all:%" PRId64,
-		    (int64_t) hist->hvalue.counters[0],
-		    (int64_t) hist->hvalue.counters[1],
-		    (int64_t) hist->hvalue.counters[2]);
-	}
-      fprintf (dump_file, ".\n");
-      break;
     case HIST_TYPE_TIME_PROFILE:
       fprintf (dump_file, "Time profile ");
       if (hist->hvalue.counters)
@@ -347,7 +341,7 @@ stream_out_histogram_value (struct output_block *ob, histogram_value hist)
       /* When user uses an unsigned type with a big value, constant converted
 	 to gcov_type (a signed type) can be negative.  */
       gcov_type value = hist->hvalue.counters[i];
-      if (hist->type == HIST_TYPE_SINGLE_VALUE && i == 0)
+      if (hist->type == HIST_TYPE_SINGLE_VALUE && (i > 0 && ((i - 1) % 2) == 0))
 	;
       else
 	gcc_assert (value >= 0);
@@ -392,7 +386,7 @@ stream_in_histogram_value (struct lto_input_block *ib, gimple *stmt)
 
 	case HIST_TYPE_SINGLE_VALUE:
 	case HIST_TYPE_INDIR_CALL:
-	  ncounters = 3;
+	  ncounters = GCOV_SINGLE_VALUE_COUNTERS;
 	  break;
 
 	case HIST_TYPE_IOR:
@@ -729,6 +723,48 @@ gimple_divmod_fixed_value (gassign *stmt, tree value, profile_probability prob,
   return tmp2;
 }
 
+/* Return most common value of SINGLE_VALUE histogram.  If
+   there's a unique value, return true and set VALUE and COUNT
+   arguments.  */
+
+bool
+get_most_common_single_value (gimple *stmt, const char *counter_type,
+			      histogram_value hist,
+			      gcov_type *value, gcov_type *count,
+			      gcov_type *all)
+{
+  if (hist->hvalue.counters[2] == -1)
+    return false;
+
+  *count = 0;
+  *value = 0;
+
+  gcov_type read_all = hist->hvalue.counters[0];
+
+  for (unsigned i = 0; i < GCOV_DISK_SINGLE_VALUES; i++)
+    {
+      gcov_type v = hist->hvalue.counters[2 * i + 1];
+      gcov_type c = hist->hvalue.counters[2 * i + 2];
+
+      /* Indirect calls can't be vereified.  */
+      if (stmt && check_counter (stmt, counter_type, &c, &read_all,
+				 gimple_bb (stmt)->count))
+	return false;
+
+      *all = read_all;
+
+      if (c > *count)
+	{
+	  *value = v;
+	  *count = c;
+	}
+      else if (c == *count && v > *value)
+	*value = v;
+    }
+
+  return true;
+}
+
 /* Do transform 1) on INSN if applicable.  */
 
 static bool
@@ -758,23 +794,19 @@ gimple_divmod_fixed_value_transform (gimple_stmt_iterator *si)
   if (!histogram)
     return false;
 
+  if (!get_most_common_single_value (stmt, "divmod", histogram, &val, &count,
+				     &all))
+    return false;
+
   value = histogram->hvalue.value;
-  val = histogram->hvalue.counters[0];
-  count = histogram->hvalue.counters[1];
-  all = histogram->hvalue.counters[2];
   gimple_remove_histogram_value (cfun, stmt, histogram);
 
-  /* We require that count is at least half of all; this means
-     that for the transformation to fire the value must be constant
-     at least 50% of time (and 75% gives the guarantee of usage).  */
+  /* We require that count is at least half of all.  */
   if (simple_cst_equal (gimple_assign_rhs2 (stmt), value) != 1
       || 2 * count < all
       || optimize_bb_for_size_p (gimple_bb (stmt)))
     return false;
 
-  if (check_counter (stmt, "value", &count, &all, gimple_bb (stmt)->count))
-    return false;
-
   /* Compute probability of taking the optimal path.  */
   if (all > 0)
     prob = profile_probability::probability_in_gcov_type (count, all);
@@ -1401,7 +1433,7 @@ gimple_ic_transform (gimple_stmt_iterator *gsi)
 {
   gcall *stmt;
   histogram_value histogram;
-  gcov_type val, count, all, bb_all;
+  gcov_type val, count, all;
   struct cgraph_node *direct_call;
 
   stmt = dyn_cast <gcall *> (gsi_stmt (*gsi));
@@ -1418,21 +1450,9 @@ gimple_ic_transform (gimple_stmt_iterator *gsi)
   if (!histogram)
     return false;
 
-  val = histogram->hvalue.counters [0];
-  count = histogram->hvalue.counters [1];
-  all = histogram->hvalue.counters [2];
-
-  bb_all = gimple_bb (stmt)->count.ipa ().to_gcov_type ();
-  /* The order of CHECK_COUNTER calls is important -
-     since check_counter can correct the third parameter
-     and we want to make count <= all <= bb_all. */
-  if (check_counter (stmt, "ic", &all, &bb_all, gimple_bb (stmt)->count)
-      || check_counter (stmt, "ic", &count, &all,
-		        profile_count::from_gcov_type (all)))
-    {
-      gimple_remove_histogram_value (cfun, stmt, histogram);
-      return false;
-    }
+  if (!get_most_common_single_value (NULL, "indirect call", histogram, &val,
+				     &count, &all))
+    return false;
 
   if (4 * count <= 3 * all)
     return false;
@@ -1644,19 +1664,19 @@ gimple_stringops_transform (gimple_stmt_iterator *gsi)
   if (TREE_CODE (blck_size) == INTEGER_CST)
     return false;
 
-  histogram = gimple_histogram_value_of_type (cfun, stmt, HIST_TYPE_SINGLE_VALUE);
+  histogram = gimple_histogram_value_of_type (cfun, stmt,
+					      HIST_TYPE_SINGLE_VALUE);
   if (!histogram)
     return false;
 
-  val = histogram->hvalue.counters[0];
-  count = histogram->hvalue.counters[1];
-  all = histogram->hvalue.counters[2];
+  if (!get_most_common_single_value (stmt, "stringops", histogram, &val,
+				     &count, &all))
+    return false;
+
   gimple_remove_histogram_value (cfun, stmt, histogram);
 
-  /* We require that count is at least half of all; this means
-     that for the transformation to fire the value must be constant
-     at least 80% of time.  */
-  if ((6 * count / 5) < all || optimize_bb_for_size_p (gimple_bb (stmt)))
+  /* We require that count is at least half of all.  */
+  if (2 * count < all || optimize_bb_for_size_p (gimple_bb (stmt)))
     return false;
   if (check_counter (stmt, "value", &count, &all, gimple_bb (stmt)->count))
     return false;
@@ -1928,11 +1948,11 @@ gimple_find_values_to_profile (histogram_values *values)
 	  break;
 
 	case HIST_TYPE_SINGLE_VALUE:
-	  hist->n_counters = 3;
+	  hist->n_counters = GCOV_SINGLE_VALUE_COUNTERS;
 	  break;
 
- 	case HIST_TYPE_INDIR_CALL:
- 	  hist->n_counters = 3;
+	case HIST_TYPE_INDIR_CALL:
+	  hist->n_counters = GCOV_SINGLE_VALUE_COUNTERS;
 	  break;
 
         case HIST_TYPE_TIME_PROFILE:
diff --git a/gcc/value-prof.h b/gcc/value-prof.h
index a54024b48de..25b03f7591a 100644
--- a/gcc/value-prof.h
+++ b/gcc/value-prof.h
@@ -90,6 +90,10 @@ void free_histograms (function *);
 void stringop_block_profile (gimple *, unsigned int *, HOST_WIDE_INT *);
 gcall *gimple_ic (gcall *, struct cgraph_node *, profile_probability);
 bool check_ic_target (gcall *, struct cgraph_node *);
+bool get_most_common_single_value (gimple *stmt, const char *counter_type,
+				   histogram_value hist,
+				   gcov_type *value, gcov_type *count,
+				   gcov_type *all);
 
 
 /* In tree-profile.c.  */
diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 7ef347a1834..669041e505f 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,27 @@
+2019-06-10  Martin Liska  <mliska@suse.cz>
+
+	* Makefile.in: Add __gcov_one_value_profiler_v2,
+	__gcov_one_value_profiler_v2_atomic and
+	__gcov_indirect_call_profiler_v4.
+	* libgcov-merge.c (__gcov_merge_single): Change
+	function signature.
+	(merge_single_value_set): New.
+	* libgcov-profiler.c (__gcov_one_value_profiler_body):
+	Update functionality.
+	(__gcov_one_value_profiler): Remove.
+	(__gcov_one_value_profiler_v2): ... this.
+	(__gcov_one_value_profiler_atomic): Rename to ...
+	(__gcov_one_value_profiler_v2_atomic): this.
+	(__gcov_indirect_call_profiler_v3): Rename to ...
+	(__gcov_indirect_call_profiler_v4): ... this.
+	* libgcov.h (__gcov_one_value_profiler): Remove.
+	(__gcov_one_value_profiler_atomic): Remove.
+	(__gcov_one_value_profiler_v2_atomic): New.
+	(__gcov_indirect_call_profiler_v3): Remove.
+	(__gcov_one_value_profiler_v2): New.
+	(__gcov_indirect_call_profiler_v4): New.
+	(gcov_get_counter_ignore_scaling): New function.
+
 2019-06-07  Martin Liska  <mliska@suse.cz>
 
 	* Makefile.in: Remove usage of
diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index fb77881145e..33b83809cfc 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -893,13 +893,13 @@ LIBGCOV_PROFILER = _gcov_interval_profiler				\
 	_gcov_interval_profiler_atomic					\
 	_gcov_pow2_profiler						\
 	_gcov_pow2_profiler_atomic					\
-	_gcov_one_value_profiler					\
-	_gcov_one_value_profiler_atomic					\
+	_gcov_one_value_profiler_v2					\
+	_gcov_one_value_profiler_v2_atomic					\
 	_gcov_average_profiler						\
 	_gcov_average_profiler_atomic					\
 	_gcov_ior_profiler						\
 	_gcov_ior_profiler_atomic					\
-	_gcov_indirect_call_profiler_v3					\
+	_gcov_indirect_call_profiler_v4					\
 	_gcov_time_profiler
 LIBGCOV_INTERFACE = _gcov_dump _gcov_flush _gcov_fork			\
 	_gcov_execl _gcov_execlp					\
diff --git a/libgcc/libgcov-merge.c b/libgcc/libgcov-merge.c
index 702a69f8349..42416341b4d 100644
--- a/libgcc/libgcov-merge.c
+++ b/libgcc/libgcov-merge.c
@@ -34,8 +34,9 @@ void __gcov_merge_add (gcov_type *counters  __attribute__ ((unused)),
 #endif
 
 #ifdef L_gcov_merge_single
-void __gcov_merge_single (gcov_type *counters  __attribute__ ((unused)),
-                          unsigned n_counters __attribute__ ((unused))) {}
+void __gcov_merge_single (gcov_type *counters  __attribute__ ((unused)))
+{
+}
 #endif
 
 #else
@@ -85,40 +86,72 @@ __gcov_merge_time_profile (gcov_type *counters, unsigned n_counters)
 #endif /* L_gcov_merge_time_profile */
 
 #ifdef L_gcov_merge_single
+
+static void
+merge_single_value_set (gcov_type *counters)
+{
+  unsigned j;
+  gcov_type value, counter;
+
+  /* First value is number of total executions of the profiler.  */
+  gcov_type all = gcov_get_counter_ignore_scaling (-1);
+  counters[0] += all;
+  ++counters;
+
+  for (unsigned i = 0; i < GCOV_DISK_SINGLE_VALUES; i++)
+    {
+      value = gcov_get_counter_target ();
+      counter = gcov_get_counter_ignore_scaling (-1);
+
+      if (counter == -1)
+	{
+	  counters[1] = -1;
+	  /* We can't return as we need to read all counters.  */
+	  continue;
+	}
+      else if (counter == 0 || counters[1] == -1)
+	{
+	  /* We can't return as we need to read all counters.  */
+	  continue;
+	}
+
+      for (j = 0; j < GCOV_DISK_SINGLE_VALUES; j++)
+	{
+	  if (counters[2 * j] == value)
+	    {
+	      counters[2 * j + 1] += counter;
+	      break;
+	    }
+	  else if (counters[2 * j + 1] == 0)
+	    {
+	      counters[2 * j] = value;
+	      counters[2 * j + 1] = counter;
+	      break;
+	    }
+	}
+
+      /* We haven't found a free slot for the value, mark overflow.  */
+      if (j == GCOV_DISK_SINGLE_VALUES)
+	counters[1] = -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
-   are split into 3-tuples where the members of the tuple have
+   are split into pairs where the members of the tuple have
    meanings:
 
    -- the stored candidate on the most common value of the measured entity
    -- counter
-   -- total number of evaluations of the value  */
+   */
 void
 __gcov_merge_single (gcov_type *counters, unsigned n_counters)
 {
-  unsigned i, n_measures;
-  gcov_type value, counter, all;
+  gcc_assert (!(n_counters % GCOV_SINGLE_VALUE_COUNTERS));
 
-  gcc_assert (!(n_counters % 3));
-  n_measures = n_counters / 3;
-  for (i = 0; i < n_measures; i++, counters += 3)
-    {
-      value = gcov_get_counter_target ();
-      counter = gcov_get_counter ();
-      all = gcov_get_counter ();
-
-      if (counters[0] == value)
-        counters[1] += counter;
-      else if (counter > counters[1])
-        {
-          counters[0] = value;
-          counters[1] = counter - counters[1];
-        }
-      else
-        counters[1] -= counter;
-      counters[2] += all;
-    }
+  for (unsigned i = 0; i < (n_counters / GCOV_SINGLE_VALUE_COUNTERS); i++)
+    merge_single_value_set (counters + (i * GCOV_SINGLE_VALUE_COUNTERS));
 }
 #endif /* L_gcov_merge_single */
 
diff --git a/libgcc/libgcov-profiler.c b/libgcc/libgcov-profiler.c
index 40f0858a174..9ba65b90df3 100644
--- a/libgcc/libgcov-profiler.c
+++ b/libgcc/libgcov-profiler.c
@@ -112,40 +112,37 @@ __gcov_pow2_profiler_atomic (gcov_type *counters, gcov_type value)
    COUNTERS[1] is decremented.  Otherwise COUNTERS[1] is set to one and
    VALUE is stored to COUNTERS[0].  This algorithm guarantees that if this
    function is called more than 50% of the time with one value, this value
-   will be in COUNTERS[0] in the end.
-
-   In any case, COUNTERS[2] is incremented.  If USE_ATOMIC is set to 1,
-   COUNTERS[2] is updated with an atomic instruction.  */
+   will be in COUNTERS[0] in the end.  */
 
 static inline void
 __gcov_one_value_profiler_body (gcov_type *counters, gcov_type value,
 				int use_atomic)
 {
-  if (value == counters[0])
-    counters[1]++;
-  else if (counters[1] == 0)
+  if (value == counters[1])
+    counters[2]++;
+  else if (counters[2] == 0)
     {
-      counters[1] = 1;
-      counters[0] = value;
+      counters[2] = 1;
+      counters[1] = value;
     }
   else
-    counters[1]--;
+    counters[2]--;
 
   if (use_atomic)
-    __atomic_fetch_add (&counters[2], 1, __ATOMIC_RELAXED);
+    __atomic_fetch_add (&counters[0], 1, __ATOMIC_RELAXED);
   else
-    counters[2]++;
+    counters[0]++;
 }
 
-#ifdef L_gcov_one_value_profiler
+#ifdef L_gcov_one_value_profiler_v2
 void
-__gcov_one_value_profiler (gcov_type *counters, gcov_type value)
+__gcov_one_value_profiler_v2 (gcov_type *counters, gcov_type value)
 {
   __gcov_one_value_profiler_body (counters, value, 0);
 }
 #endif
 
-#if defined(L_gcov_one_value_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
+#if defined(L_gcov_one_value_profiler_v2_atomic) && GCOV_SUPPORTS_ATOMIC
 
 /* Update one value profilers (COUNTERS) for a given VALUE.
 
@@ -157,13 +154,13 @@ __gcov_one_value_profiler (gcov_type *counters, gcov_type value)
    https://gcc.gnu.org/ml/gcc-patches/2016-08/msg00024.html.  */
 
 void
-__gcov_one_value_profiler_atomic (gcov_type *counters, gcov_type value)
+__gcov_one_value_profiler_v2_atomic (gcov_type *counters, gcov_type value)
 {
   __gcov_one_value_profiler_body (counters, value, 1);
 }
 #endif
 
-#ifdef L_gcov_indirect_call_profiler_v3
+#ifdef L_gcov_indirect_call_profiler_v4
 
 /* These two variables are used to actually track caller and callee.  Keep
    them in TLS memory so races are not common (they are written to often).
@@ -185,7 +182,7 @@ struct indirect_call_tuple __gcov_indirect_call;
 
 /* Tries to determine the most common value among its inputs. */
 void
-__gcov_indirect_call_profiler_v3 (gcov_type value, void* cur_func)
+__gcov_indirect_call_profiler_v4 (gcov_type value, void* cur_func)
 {
   /* If the C++ virtual tables contain function descriptors then one
      function may have multiple descriptors and we need to dereference
diff --git a/libgcc/libgcov.h b/libgcc/libgcov.h
index b4f1ec576fc..144b4817a37 100644
--- a/libgcc/libgcov.h
+++ b/libgcc/libgcov.h
@@ -271,9 +271,9 @@ extern void __gcov_interval_profiler_atomic (gcov_type *, gcov_type, int,
 					     unsigned);
 extern void __gcov_pow2_profiler (gcov_type *, gcov_type);
 extern void __gcov_pow2_profiler_atomic (gcov_type *, gcov_type);
-extern void __gcov_one_value_profiler (gcov_type *, gcov_type);
-extern void __gcov_one_value_profiler_atomic (gcov_type *, gcov_type);
-extern void __gcov_indirect_call_profiler_v3 (gcov_type, void *);
+extern void __gcov_one_value_profiler_v2 (gcov_type *, gcov_type);
+extern void __gcov_one_value_profiler_v2_atomic (gcov_type *, gcov_type);
+extern void __gcov_indirect_call_profiler_v4 (gcov_type, void *);
 extern void __gcov_time_profiler (gcov_type *);
 extern void __gcov_time_profiler_atomic (gcov_type *);
 extern void __gcov_average_profiler (gcov_type *, gcov_type);
@@ -324,6 +324,29 @@ gcov_get_counter (void)
 #endif
 }
 
+/* Similar function as gcov_get_counter(), but do not scale
+   when read value is equal to IGNORE_SCALING.  */
+
+static inline gcov_type
+gcov_get_counter_ignore_scaling (gcov_type ignore_scaling)
+{
+#ifndef IN_GCOV_TOOL
+  /* This version is for reading count values in libgcov runtime:
+     we read from gcda files.  */
+
+  return gcov_read_counter ();
+#else
+  /* This version is for gcov-tool. We read the value from memory and
+     multiply it by the merge weight.  */
+
+  gcov_type v = gcov_read_counter_mem ();
+  if (v != ignore_scaling)
+    v *= gcov_get_merge_weight ();
+
+  return v;
+#endif
+}
+
 /* Similar function as gcov_get_counter(), but handles target address
    counters.  */