2017-06-27  Segher Boessenkool  <segher@kernel.crashing.org>

	Backport from trunk

	2017-05-17  Segher Boessenkool  <segher@kernel.crashing.org>

	PR middle-end/80692

	* real.c (do_compare): Give decimal_do_compare preference over

	comparing just the signs.

	* gcc.c-torture/execute/pr80692.c: New testcase.

--- gcc/real.c

+++ gcc/real.c

@@ -950,12 +950,12 @@ do_compare (const REAL_VALUE_TYPE *a, const REAL_VALUE_TYPE *b,

       gcc_unreachable ();

     }

-  if (a->sign != b->sign)

-    return -a->sign - -b->sign;

-

   if (a->decimal || b->decimal)

     return decimal_do_compare (a, b, nan_result);

+  if (a->sign != b->sign)

+    return -a->sign - -b->sign;

+

   if (REAL_EXP (a) > REAL_EXP (b))

     ret = 1;

   else if (REAL_EXP (a) < REAL_EXP (b))

--- /dev/null

+++ gcc/testsuite/gcc.c-torture/execute/pr80692.c

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

+int main () {

+	_Decimal64 d64 = -0.DD;

+

+	if (d64 != 0.DD)

+		__builtin_abort ();

+

+	if (d64 != -0.DD)

+		__builtin_abort ();

+

+	return 0;

+}

--- /dev/null

+++ gcc/testsuite/gcc.c-torture/execute/pr80692.x

@@ -0,0 +1,7 @@

+load_lib target-supports.exp

+

+if { ! [check_effective_target_dfp] } {

+        return 1

+}

+

+return 0