Restore profile reproducibility.

gcc/ChangeLog:

	PR gcov-profile/98739
	* common.opt: Add missing sign symbol.
	* value-prof.c (get_nth_most_common_value): Restore handling
	of PROFILE_REPRODUCIBILITY_PARALLEL_RUNS and
	PROFILE_REPRODUCIBILITY_MULTITHREADED.

libgcc/ChangeLog:

	PR gcov-profile/98739
	* libgcov-merge.c (__gcov_merge_topn): Mark when merging
	ends with a dropped counter.
	* libgcov.h (gcov_topn_add_value): Add return value.

gcc/common.opt

@@ -2248,7 +2248,7 @@ Enum(profile_reproducibility) String(parallel-runs) Value(PROFILE_REPRODUCIBILIT
 EnumValue
 Enum(profile_reproducibility) String(multithreaded) Value(PROFILE_REPRODUCIBILITY_MULTITHREADED)
 
-fprofile-reproducible
+fprofile-reproducible=
 Common Joined RejectNegative Var(flag_profile_reproducible) Enum(profile_reproducibility) Init(PROFILE_REPRODUCIBILITY_SERIAL)
 -fprofile-reproducible=[serial|parallel-runs|multithreaded]	Control level of reproducibility of profile gathered by -fprofile-generate.
 

gcc/value-prof.c

@@ -747,8 +747,8 @@ gimple_divmod_fixed_value (gassign *stmt, tree value, profile_probability prob,
 
    abs (counters[0]) is the number of executions
    for i in 0 ... TOPN-1
-     counters[2 * i + 1] is target
-     abs (counters[2 * i + 2]) is corresponding hitrate counter.
+     counters[2 * i + 2] is target
+     counters[2 * i + 3] is corresponding hitrate counter.
 
    Value of counters[0] negative when counter became
    full during merging and some values are lost.  */
@@ -766,15 +766,29 @@ get_nth_most_common_value (gimple *stmt, const char *counter_type,
   *value = 0;
 
   gcov_type read_all = abs_hwi (hist->hvalue.counters[0]);
+  gcov_type covered = 0;
+  for (unsigned i = 0; i < counters; ++i)
+    covered += hist->hvalue.counters[2 * i + 3];
 
   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
-	  || (flag_profile_reproducible
-	      == PROFILE_REPRODUCIBILITY_MULTITHREADED)))
-    return false;
+      && flag_profile_reproducible == PROFILE_REPRODUCIBILITY_PARALLEL_RUNS)
+    {
+      if (dump_file)
+	fprintf (dump_file, "Histogram value dropped in %qs mode",
+		 "-fprofile-reproducible=parallel-runs");
+      return false;
+    }
+  else if (covered != read_all
+	   && flag_profile_reproducible == PROFILE_REPRODUCIBILITY_MULTITHREADED)
+    {
+      if (dump_file)
+	fprintf (dump_file, "Histogram value dropped in %qs mode",
+		 "-fprofile-reproducible=multithreaded");
+      return false;
+    }
 
   /* Indirect calls can't be verified.  */
   if (stmt

libgcc/libgcov-merge.c

@@ -94,6 +94,9 @@ __gcov_merge_time_profile (gcov_type *counters, unsigned n_counters)
 
    -- the stored candidate on the most common value of the measured entity
    -- counter
+
+   We use -TOTAL for situation when merging dropped some values.
+   The information is used for -fprofile-reproducible flag.
    */
 
 void
@@ -107,7 +110,9 @@ __gcov_merge_topn (gcov_type *counters, unsigned n_counters)
       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;
+      unsigned full = all < 0;
+      gcov_type *total = &counters[GCOV_TOPN_MEM_COUNTERS * i];
+      *total += full ? -all : all;
 
       for (unsigned j = 0; j < n; j++)
 	{
@@ -115,9 +120,12 @@ __gcov_merge_topn (gcov_type *counters, unsigned n_counters)
 	  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);
+	  full |= gcov_topn_add_value (counters + GCOV_TOPN_MEM_COUNTERS * i,
+				       value, count, 0, 0);
 	}
+
+      if (full)
+	*total = -(*total);
     }
 }
 #endif /* L_gcov_merge_topn */

libgcc/libgcov.h

@@ -435,9 +435,10 @@ allocate_gcov_kvp (void)
 
 /* 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.  */
+   do it in atomic way.  Return true when the counter is full, otherwise
+   return false.  */
 
-static inline void
+static inline unsigned
 gcov_topn_add_value (gcov_type *counters, gcov_type value, gcov_type count,
 		     int use_atomic, int increment_total)
 {
@@ -453,7 +454,7 @@ gcov_topn_add_value (gcov_type *counters, gcov_type value, gcov_type count,
       if (current_node->value == value)
 	{
 	  gcov_counter_add (&current_node->count, count, use_atomic);
-	  return;
+	  return 0;
 	}
 
       if (minimal_node == NULL
@@ -471,12 +472,14 @@ gcov_topn_add_value (gcov_type *counters, gcov_type value, gcov_type count,
 	  minimal_node->value = value;
 	  minimal_node->count = count;
 	}
+
+      return 1;
     }
   else
     {
       struct gcov_kvp *new_node = allocate_gcov_kvp ();
       if (new_node == NULL)
-	return;
+	return 0;
 
       new_node->value = value;
       new_node->count = count;
@@ -515,6 +518,8 @@ gcov_topn_add_value (gcov_type *counters, gcov_type value, gcov_type count,
       if (success)
 	gcov_counter_add (&counters[1], 1, use_atomic);
     }
+
+  return 0;
 }
 
 #endif /* !inhibit_libc */