Regression test for x86 fp-stack breakage

From-SVN: r26430

gcc/testsuite/gcc.c-torture/execute/990413-2.c

+/* This tests for a bug in regstack that was breaking glibc's math library. */
+
+extern void abort (void);
+
+static __inline double
+minus_zero (void)
+{
+  union { double __d; int __i[2]; } __x;
+  __x.__i[0] = 0x0;
+  __x.__i[1] = 0x80000000;
+  return __x.__d;
+}
+
+static __inline long double
+__atan2l (long double __y, long double __x)
+{
+  register long double __value;
+  __asm __volatile__ ("fpatan\n\t"
+		      : "=t" (__value)
+		      : "0" (__x), "u" (__y)
+		      : "st(1)");
+  return __value;
+}
+
+static __inline long double
+__sqrtl (long double __x)
+{
+  register long double __result;
+  __asm __volatile__ ("fsqrt" : "=t" (__result) : "0" (__x));
+  return __result;
+}
+
+static __inline double
+asin (double __x)
+{
+  return __atan2l (__x, __sqrtl (1.0 - __x * __x));
+}
+
+int
+main (void)
+{
+  double x;
+
+  x = minus_zero();
+  x = asin (x);
+
+  if (x != 0.0) /* actually -0.0, but 0.0 == -0.0 */
+    abort ();
+  return 0;
+}

gcc/testsuite/gcc.c-torture/execute/990413-2.x

+# This test is x86 specific.
+if { ! [istarget "i?86-*-*"] } { return 1 }
+return 0