re PR middle-end/80362 (gcc miscompiles arithmetic with signed char)

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.

From-SVN: r246805

gcc/ChangeLog

+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.
+
 2017-04-10  Martin Liska  <mliska@suse.cz>
 
 	PR gcov-profile/80224

gcc/fold-const.c

@@ -10205,7 +10205,7 @@ 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
+	  && TREE_CODE (op0) == NEGATE_EXPR
 	  && negate_expr_p (op1))
 	{
 	  if (INTEGRAL_TYPE_P (type))

gcc/testsuite/ChangeLog

 2017-04-10  Richard Biener  <rguenther@suse.de>
 
+	PR middle-end/80362
+	* gcc.dg/torture/pr80362.c: New testcase.
+
+2017-04-10  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/80304
 	* gcc.dg/torture/pr80304.c: New testcase.
 

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

+/* { 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();
+}