[gcc r15-9072] Only write gcov when file output is on [PR119553]

[Jorgen Kvalsvik via Gcc-cvs]

https://gcc.gnu.org/g:de742091f4df997f426d99bcfed3c44914788033

commit r15-9072-gde742091f4df997f426d99bcfed3c44914788033
Author: Jørgen Kvalsvik <j...@lambda.is>
Date:   Mon Mar 31 19:03:37 2025 +0200

    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.

Diff:
---
 gcc/path-coverage.cc | 15 ++++++---------
 gcc/profile.cc       | 12 ++++++++++--
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/gcc/path-coverage.cc b/gcc/path-coverage.cc
index 55b392986035..55058fd04ff2 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 0b222cf38640..c0f5097726bd 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 ();