Only write gcov when file output is on [PR119553]

gcov_write_* functions must be guarded so they only are called when
output_to_file is true, like for -fcondition-coverage, otherwise it
triggers an invalid read as detected by valgrind. The gcno file is
mostly written to from profile.cc, so it doesn't make too much sense
to hide it in path-coverage.cc. The find_paths name was a bit
imprecise, and is renamed to instrument_prime_paths.

	PR gcov-profile/119553

gcc/ChangeLog:

	* path-coverage.cc (find_paths): Return path count, don't
	write to gcno, and rename to ...
	(instrument_prime_paths): ... this.
	* profile.cc (branch_prob): Write path counts to gcno.

2 files changed, 16 insertions, 11 deletions

diff --git a/gcc/path-coverage.cc b/gcc/path-coverage.cc
index 55b3929..55058fd 100644
--- a/gcc/path-coverage.cc
+++ b/gcc/path-coverage.cc
@@ -504,8 +504,8 @@ flush_on_gsi (gimple_stmt_iterator *gsi, size_t bucket, tree local, tree mask,
    bit N%64 in bucket N/64.  For large functions, an individual basic block
    will only be part of a small subset of paths, and by extension buckets and
    local counters.  Only the necessary counters are read and written.  */
-void
-find_paths (struct function *fn)
+unsigned
+instrument_prime_paths (struct function *fn)
 {
   mark_dfs_back_edges (fn);
   vec<vec<int>> paths = find_prime_paths (fn);
@@ -515,7 +515,7 @@ find_paths (struct function *fn)
       warning_at (fn->function_start_locus, OPT_Wcoverage_too_many_paths,
 		  "paths exceeding limit, giving up path coverage");
       release_vec_vec (paths);
-      return;
+      return 0;
     }
 
   tree gcov_type_node = get_gcov_type ();
@@ -526,14 +526,9 @@ find_paths (struct function *fn)
   if (!coverage_counter_alloc (GCOV_COUNTER_PATHS, nbuckets))
     {
       release_vec_vec (paths);
-      return;
+      return 0;
     }
 
-  gcov_position_t offset {};
-  offset = gcov_write_tag (GCOV_TAG_PATHS);
-  gcov_write_unsigned (paths.length ());
-  gcov_write_length (offset);
-
   hash_map <edge_hash, uint64_t> ands;
   hash_map <block_hash, uint64_t> iors;
   hash_map <block_hash, uint64_t> flushes;
@@ -771,6 +766,8 @@ find_paths (struct function *fn)
 	}
     }
 
+  const unsigned npaths = paths.length ();
   blocks.release ();
   release_vec_vec (paths);
+  return npaths;
 }
diff --git a/gcc/profile.cc b/gcc/profile.cc
index 0b222cf..c0f5097 100644
--- a/gcc/profile.cc
+++ b/gcc/profile.cc
@@ -1611,9 +1611,17 @@ branch_prob (bool thunk)
 	instrument_values (values);
     }
 
-  void find_paths (struct function*);
+  unsigned instrument_prime_paths (struct function*);
   if (path_coverage_flag)
-    find_paths (cfun);
+    {
+      const unsigned npaths = instrument_prime_paths (cfun);
+      if (output_to_file)
+	{
+	  gcov_position_t offset = gcov_write_tag (GCOV_TAG_PATHS);
+	  gcov_write_unsigned (npaths);
+	  gcov_write_length (offset);
+	}
+    }
 
   free_aux_for_edges ();