Test for not existence of a negative loop (PR gcov-profile/90380).

2019-05-13  Martin Liska  <mliska@suse.cz>

	PR gcov-profile/90380
	* gcov.c (enum loop_type): Remove the enum and
	the operator.
	(handle_cycle): Assert that we should not reach
	a negative count.
	(circuit): Use loop_found instead of a tri-state loop_type.
	(get_cycles_count): Do not handle NEGATIVE_LOOP as it can't
	happen.

From-SVN: r271116

1 files changed, 18 insertions, 35 deletions

diff --git a/gcc/gcov.c b/gcc/gcov.c
index 1fc37a0..6bcd2b2 100644
--- a/gcc/gcov.c
+++ b/gcc/gcov.c
@@ -676,27 +676,11 @@ bool function_info::group_line_p (unsigned n, unsigned src_idx)
 typedef vector<arc_info *> arc_vector_t;
 typedef vector<const block_info *> block_vector_t;
 
-/* Enum with types of loop in CFG.  */
-
-enum loop_type
-{
-  NO_LOOP = 0,
-  LOOP = 1,
-  NEGATIVE_LOOP = 3
-};
-
-/* Loop_type operator that merges two values: A and B.  */
-
-inline loop_type& operator |= (loop_type& a, loop_type b)
-{
-    return a = static_cast<loop_type> (a | b);
-}
-
 /* Handle cycle identified by EDGES, where the function finds minimum cs_count
    and subtract the value from all counts.  The subtracted value is added
    to COUNT.  Returns type of loop.  */
 
-static loop_type
+static void
 handle_cycle (const arc_vector_t &edges, int64_t &count)
 {
   /* Find the minimum edge of the cycle, and reduce all nodes in the cycle by
@@ -712,7 +696,7 @@ handle_cycle (const arc_vector_t &edges, int64_t &count)
   for (unsigned i = 0; i < edges.size (); i++)
     edges[i]->cs_count -= cycle_count;
 
-  return cycle_count < 0 ? NEGATIVE_LOOP : LOOP;
+  gcc_assert (cycle_count >= 0);
 }
 
 /* Unblock a block U from BLOCKED.  Apart from that, iterate all blocks
@@ -743,12 +727,12 @@ unblock (const block_info *u, block_vector_t &blocked,
    blocked by a block.  COUNT is accumulated count of the current LINE.
    Returns what type of loop it contains.  */
 
-static loop_type
+static bool
 circuit (block_info *v, arc_vector_t &path, block_info *start,
 	 block_vector_t &blocked, vector<block_vector_t> &block_lists,
 	 line_info &linfo, int64_t &count)
 {
-  loop_type result = NO_LOOP;
+  bool loop_found = false;
 
   /* Add v to the block list.  */
   gcc_assert (find (blocked.begin (), blocked.end (), v) == blocked.end ());
@@ -763,15 +747,19 @@ circuit (block_info *v, arc_vector_t &path, block_info *start,
 
       path.push_back (arc);
       if (w == start)
-	/* Cycle has been found.  */
-	result |= handle_cycle (path, count);
+	{
+	  /* Cycle has been found.  */
+	  handle_cycle (path, count);
+	  loop_found = true;
+	}
       else if (find (blocked.begin (), blocked.end (), w) == blocked.end ())
-	result |= circuit (w, path, start, blocked, block_lists, linfo, count);
+	loop_found |= circuit (w, path, start, blocked, block_lists, linfo,
+			       count);
 
       path.pop_back ();
     }
 
-  if (result != NO_LOOP)
+  if (loop_found)
     unblock (v, blocked, block_lists);
   else
     for (arc_info *arc = v->succ; arc; arc = arc->succ_next)
@@ -788,14 +776,13 @@ circuit (block_info *v, arc_vector_t &path, block_info *start,
 	  list.push_back (v);
       }
 
-  return result;
+  return loop_found;
 }
 
-/* Find cycles for a LINFO.  If HANDLE_NEGATIVE_CYCLES is set and the line
-   contains a negative loop, then perform the same function once again.  */
+/* Find cycles for a LINFO.  */
 
 static gcov_type
-get_cycles_count (line_info &linfo, bool handle_negative_cycles = true)
+get_cycles_count (line_info &linfo)
 {
   /* Note that this algorithm works even if blocks aren't in sorted order.
      Each iteration of the circuit detection is completely independent
@@ -803,7 +790,7 @@ get_cycles_count (line_info &linfo, bool handle_negative_cycles = true)
      Therefore, operating on a permuted order (i.e., non-sorted) only
      has the effect of permuting the output cycles.  */
 
-  loop_type result = NO_LOOP;
+  bool loop_found = false;
   gcov_type count = 0;
   for (vector<block_info *>::iterator it = linfo.blocks.begin ();
        it != linfo.blocks.end (); it++)
@@ -811,14 +798,10 @@ get_cycles_count (line_info &linfo, bool handle_negative_cycles = true)
       arc_vector_t path;
       block_vector_t blocked;
       vector<block_vector_t > block_lists;
-      result |= circuit (*it, path, *it, blocked, block_lists, linfo,
-			 count);
+      loop_found |= circuit (*it, path, *it, blocked, block_lists, linfo,
+			     count);
     }
 
-  /* If we have a negative cycle, repeat the find_cycles routine.  */
-  if (result == NEGATIVE_LOOP && handle_negative_cycles)
-    count += get_cycles_count (linfo, false);
-
   return count;
 }