Fix try_transform_to_exit_first_loop_alt

2015-06-06  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/66442
	* gimple-iterator.h (gimple_seq_nondebug_singleton_p): Add function.
	* tree-parloops.c (try_transform_to_exit_first_loop_alt): Return false
	if the loop latch is not a singleton.  Use
	gimple_seq_nondebug_singleton_p instead of gimple_seq_singleton_p.
---
 gcc/gimple-iterator.h | 29 +++++++++++++++++++++++++++++
 gcc/tree-parloops.c   |  4 ++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/gcc/gimple-iterator.h b/gcc/gimple-iterator.h
index 87e943a..76fa456 100644
--- a/gcc/gimple-iterator.h
+++ b/gcc/gimple-iterator.h
@@ -345,4 +345,33 @@ gsi_seq (gimple_stmt_iterator i)
   return *i.seq;
 }
 
+/* Determine whether SEQ is a nondebug singleton.  */
+
+static inline bool
+gimple_seq_nondebug_singleton_p (gimple_seq seq)
+{
+  gimple_stmt_iterator gsi;
+
+  /* Find a nondebug gimple.  */
+  gsi.ptr = gimple_seq_first (seq);
+  gsi.seq = &seq;
+  gsi.bb = NULL;
+  while (!gsi_end_p (gsi)
+	 && is_gimple_debug (gsi_stmt (gsi)))
+    gsi_next (&gsi);
+
+  /* No nondebug gimple found, not a singleton.  */
+  if (gsi_end_p (gsi))
+    return false;
+
+  /* Find a next nondebug gimple.  */
+  gsi_next (&gsi);
+  while (!gsi_end_p (gsi)
+	 && is_gimple_debug (gsi_stmt (gsi)))
+    gsi_next (&gsi);
+
+  /* Only a singleton if there's no next nondebug gimple.  */
+  return gsi_end_p (gsi);
+}
+
 #endif /* GCC_GIMPLE_ITERATOR_H */
diff --git a/gcc/tree-parloops.c b/gcc/tree-parloops.c
index 02f44eb..c4b83fe 100644
--- a/gcc/tree-parloops.c
+++ b/gcc/tree-parloops.c
@@ -1769,8 +1769,8 @@ try_transform_to_exit_first_loop_alt (struct loop *loop,
 				      tree nit)
 {
   /* Check whether the latch contains a single statement.  */
-  if (!gimple_seq_singleton_p (bb_seq (loop->latch)))
-    return true;
+  if (!gimple_seq_nondebug_singleton_p (bb_seq (loop->latch)))
+    return false;
 
   /* Check whether the latch contains the loop iv increment.  */
   edge back = single_succ_edge (loop->latch);
-- 
1.9.1