re PR middle-end/79818 (wrong code with -fwrapv and -Os/-O1/-O2/-O3)

2017-03-03  Richard Biener  <rguenther@suse.de>

	PR middle-end/79818
	* match.pd ( X +- C1 CMP C2 -> X CMP C2 -+ C1): Add missing
	TYPE_OVERFLOW_UNDEFINED check.

	* gcc.dg/torture/pr79818.c: New testcase.

From-SVN: r245860

gcc/ChangeLog

+2017-03-03  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/79818
+	* match.pd ( X +- C1 CMP C2 -> X CMP C2 -+ C1): Add missing
+	TYPE_OVERFLOW_UNDEFINED check.
+
 2017-03-02  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
 
 	* config/rs6000/vector.md (vector_ne_<mode>_p): Correct operand

gcc/match.pd

@@ -3688,7 +3688,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 	&& !TYPE_OVERFLOW_TRAPS (TREE_TYPE (@0))
 	&& !TYPE_SATURATING (TREE_TYPE (@0)))
     (with { tree res = int_const_binop (rop, @2, @1); }
-     (if (TREE_OVERFLOW (res))
+     (if (TREE_OVERFLOW (res)
+	  && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
       { constant_boolean_node (cmp == NE_EXPR, type); }
       (if (single_use (@3))
        (cmp @0 { res; }))))))))

gcc/testsuite/ChangeLog

+2017-03-03  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/79818
+	* gcc.dg/torture/pr79818.c: New testcase.
+
 2017-03-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/79782

gcc/testsuite/gcc.dg/torture/pr79818.c

+/* { dg-do run } */
+/* { dg-additional-options "-fwrapv" } */
+
+static void __attribute__((noinline,noclone))
+func(void)
+{
+  signed char c = 0;
+
+  for(; c >= 0; c++);
+
+  if(c != -128)
+    __builtin_abort();
+}
+
+int main(int argc, char* argv[])
+{
+  func();
+  return 0;
+}