Allow non-overflow ops in reductions

2015-08-01  Tom de Vries  <tom@codesourcery.com>

	* tree.c (operation_can_overflow, operation_no_trapping_overflow): New
	function.
	* tree.h (operation_can_overflow, operation_no_trapping_overflow):
	Declare.
	* tree-vect-loop.c (vect_is_simple_reduction_1): Use
	operation_no_trapping_overflow.  Allow non-overflow operations.
	* graphite-sese-to-poly.c (is_reduction_operation_p): Allow non-overflow
	operations.

	* gcc.dg/autopar/reduc-2char.c (init_arrays): Mark with attribute
	optimize ("-ftree-parallelize-loops=0").
	Add successful scans for 2 detected reductions.	 Add xfail scans for 3
	detected reductions.
	* gcc.dg/autopar/reduc-2short.c: Same.
	* gcc.dg/autopar/reduc-8.c (init_arrays): Mark with attribute
	optimize ("-ftree-parallelize-loops=0").  Add successful scans for 2
	detected reductions.
	* gcc.dg/vect/trapv-vect-reduc-4.c: Update scan to match vectorized min
	and max reductions.

From-SVN: r226463

1 files changed, 69 insertions, 0 deletions

diff --git a/gcc/tree.c b/gcc/tree.c
index 94263af..3c2c20a 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -7597,6 +7597,75 @@ commutative_ternary_tree_code (enum tree_code code)
   return false;
 }
 
+/* Returns true if CODE can overflow.  */
+
+bool
+operation_can_overflow (enum tree_code code)
+{
+  switch (code)
+    {
+    case PLUS_EXPR:
+    case MINUS_EXPR:
+    case MULT_EXPR:
+    case LSHIFT_EXPR:
+      /* Can overflow in various ways.  */
+      return true;
+    case TRUNC_DIV_EXPR:
+    case EXACT_DIV_EXPR:
+    case FLOOR_DIV_EXPR:
+    case CEIL_DIV_EXPR:
+      /* For INT_MIN / -1.  */
+      return true;
+    case NEGATE_EXPR:
+    case ABS_EXPR:
+      /* For -INT_MIN.  */
+      return true;
+    default:
+      /* These operators cannot overflow.  */
+      return false;
+    }
+}
+
+/* Returns true if CODE operating on operands of type TYPE doesn't overflow, or
+   ftrapv doesn't generate trapping insns for CODE.  */
+
+bool
+operation_no_trapping_overflow (tree type, enum tree_code code)
+{
+  gcc_checking_assert (ANY_INTEGRAL_TYPE_P (type));
+
+  /* We don't generate instructions that trap on overflow for complex or vector
+     types.  */
+  if (!INTEGRAL_TYPE_P (type))
+    return true;
+
+  if (!TYPE_OVERFLOW_TRAPS (type))
+    return true;
+
+  switch (code)
+    {
+    case PLUS_EXPR:
+    case MINUS_EXPR:
+    case MULT_EXPR:
+    case NEGATE_EXPR:
+    case ABS_EXPR:
+      /* These operators can overflow, and -ftrapv generates trapping code for
+	 these.  */
+      return false;
+    case TRUNC_DIV_EXPR:
+    case EXACT_DIV_EXPR:
+    case FLOOR_DIV_EXPR:
+    case CEIL_DIV_EXPR:
+    case LSHIFT_EXPR:
+      /* These operators can overflow, but -ftrapv does not generate trapping
+	 code for these.  */
+      return true;
+    default:
+      /* These operators cannot overflow.  */
+      return true;
+    }
+}
+
 namespace inchash
 {