2017-09-18  Richard Biener  <rguenther@suse.de>

	Backport from mainline

	2017-04-10  Richard Biener  <rguenther@suse.de>

	PR middle-end/80362

	* fold-const.c (fold_binary_loc): Look at unstripped ops when

	looking for NEGATE_EXPR in -A / -B to A / B folding.

	* gcc.dg/torture/pr80362.c: New testcase.

--- gcc/fold-const.c

+++ gcc/fold-const.c

@@ -11940,8 +11942,8 @@ fold_binary_loc (location_t loc,

       /* Convert -A / -B to A / B when the type is signed and overflow is

 	 undefined.  */

       if ((!INTEGRAL_TYPE_P (type) || TYPE_OVERFLOW_UNDEFINED (type))

-	  && TREE_CODE (arg0) == NEGATE_EXPR

-	  && negate_expr_p (arg1))

+	  && TREE_CODE (op0) == NEGATE_EXPR

+	  && negate_expr_p (op1))

 	{

 	  if (INTEGRAL_TYPE_P (type))

 	    fold_overflow_warning (("assuming signed overflow does not occur "

--- /dev/null

+++ gcc/testsuite/gcc.dg/torture/pr80362.c

@@ -0,0 +1,11 @@

+/* { dg-do run } */

+/* { dg-additional-options "-fstrict-overflow" } */

+

+int main()

+{

+  signed char var_0, var_1 = -128;

+  var_0 = (signed char)(-var_1) / 3;

+  if (var_0 > 0)

+    __builtin_abort();

+  return 0;

+}