add test for copysign of negative zero

Author: kripken

tests/core/test_negative_zero.in

@@ -1,6 +1,24 @@
 #include <stdio.h>
 #include <math.h>
 
+// test copysign of 0
+int __attribute__((noinline,noclone))
+copysign_bug (double x)
+{
+  if (x != 0.0 && (x * 0.5 == x)) {
+    printf("1\n");
+    return 1;
+  }
+  printf("f: %f\n", x);
+  if (__builtin_copysign(1.0, x) < 0.0) {
+    printf("2\n");
+    return 2;
+  } else {
+    printf("3\n");
+    return 3;
+  }
+}
+
 int main() {
 #define TEST(x, y) printf("%.2f, %.2f ==> %.2f\n", x, y, copysign(x, y));
   TEST(5.0f, 5.0f);
@@ -23,5 +41,10 @@ int main() {
   TEST(0.0f, -0.0f);
   TEST(-0.0f, 0.0f);
   TEST(-0.0f, -0.0f);
+
+  double x = -0.0;
+  if (copysign_bug (x) != 2)
+    __builtin_abort ();
+
   return 0;
 }

tests/core/test_negative_zero.out

@@ -18,3 +18,5 @@
 0.00, -0.00 ==> -0.00
 -0.00, 0.00 ==> 0.00
 -0.00, -0.00 ==> -0.00
+f: -0.000000
+2