2016-01-27 Richard Biener <rguenther@suse.de>

	PR tree-optimization/69166
	* tree-vect-loop.c (vect_is_simple_reduction): Always check
	reduction code for commutativity / associativity.

	* gcc.dg/torture/pr69166.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@232878 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 39 insertions, 14 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 824c69c1859..9f8869b6f6d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-01-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69166
+	* tree-vect-loop.c (vect_is_simple_reduction): Always check
+	reduction code for commutativity / associativity.
+
 2016-01-27  Martin Jambor  <mjambor@suse.cz>
 
 	PR tree-optimization/69355
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7dae86c1fe0..8c7f4ddb371 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-01-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69166
+	* gcc.dg/torture/pr69166.c: New testcase.
+
 2016-01-27  Martin Jambor  <mjambor@suse.cz>
 
 	PR tree-optimization/69355
diff --git a/gcc/testsuite/gcc.dg/torture/pr69166.c b/gcc/testsuite/gcc.dg/torture/pr69166.c
new file mode 100644
index 00000000000..c10f8e65357
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr69166.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+
+void fn2(double *e, double a)
+{
+  int b = 0;
+  for (; b < 256; b++)
+    {
+      int c = 0;
+      double x = e[b];
+      for (; c < 256; ++c)
+	x /= a;
+      e[b] = x;
+    }
+}
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 60346725a44..b8303ad4139 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -2750,17 +2750,17 @@ vect_is_simple_reduction (loop_vec_info loop_info, gimple *phi,
       && SSA_NAME_DEF_STMT (op1) == phi)
     code = PLUS_EXPR;
 
-  if (check_reduction)
+  if (code == COND_EXPR)
     {
-      if (code == COND_EXPR)
+      if (check_reduction)
 	*v_reduc_type = COND_REDUCTION;
-      else if (!commutative_tree_code (code) || !associative_tree_code (code))
-	{
-	  if (dump_enabled_p ())
-	    report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
-			    "reduction: not commutative/associative: ");
-	  return NULL;
-	}
+    }
+  else if (!commutative_tree_code (code) || !associative_tree_code (code))
+    {
+      if (dump_enabled_p ())
+	report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
+			"reduction: not commutative/associative: ");
+      return NULL;
     }
 
   if (get_gimple_rhs_class (code) != GIMPLE_BINARY_RHS)
@@ -2856,11 +2856,11 @@ vect_is_simple_reduction (loop_vec_info loop_info, gimple *phi,
      and therefore vectorizing reductions in the inner-loop during
      outer-loop vectorization is safe.  */
 
-  if (*v_reduc_type != COND_REDUCTION)
+  if (*v_reduc_type != COND_REDUCTION
+      && check_reduction)
     {
       /* CHECKME: check for !flag_finite_math_only too?  */
-      if (SCALAR_FLOAT_TYPE_P (type) && !flag_associative_math
-	  && check_reduction)
+      if (SCALAR_FLOAT_TYPE_P (type) && !flag_associative_math)
 	{
 	  /* Changing the order of operations changes the semantics.  */
 	  if (dump_enabled_p ())
@@ -2868,7 +2868,7 @@ vect_is_simple_reduction (loop_vec_info loop_info, gimple *phi,
 			"reduction: unsafe fp math optimization: ");
 	  return NULL;
 	}
-      else if (INTEGRAL_TYPE_P (type) && check_reduction)
+      else if (INTEGRAL_TYPE_P (type))
 	{
 	  if (!operation_no_trapping_overflow (type, code))
 	    {
@@ -2891,7 +2891,7 @@ vect_is_simple_reduction (loop_vec_info loop_info, gimple *phi,
 	      return NULL;
 	    }
 	}
-      else if (SAT_FIXED_POINT_TYPE_P (type) && check_reduction)
+      else if (SAT_FIXED_POINT_TYPE_P (type))
 	{
 	  /* Changing the order of operations changes the semantics.  */
 	  if (dump_enabled_p ())