gcc/testsuite/gcc.dg/980414-1.c

   1 /* Test double on x86. */
   2
   3 /* { dg-do run { target i?86-*-* } } */
   4 /* { dg-options -O2 } */
   5
   6 extern void abort (void);
   7
   8 static __inline  double
   9 mypow (double __x, double __y)
  10 {
  11   register double __value, __exponent;
  12   long __p = (long) __y;
  13   if (__y == (double) __p)
  14     {
  15       double __r = 1.0;
  16       if (__p == 0)
  17         return 1.0;
  18       if (__p < 0)
  19         {
  20           __p = -__p;
  21           __x = 1.0 / __x;
  22         }
  23       while (1)
  24         {
  25           if (__p & 1)
  26             __r *= __x;
  27           __p >>= 1;
  28           if (__p == 0)
  29             return __r;
  30           __x *= __x;
  31         }
  32     }
  33   __asm __volatile__
  34     ("fmul      %%st(1),%%st\n\t"       /* y * log2(x) */
  35      "fst       %%st(1)\n\t"
  36      "frndint\n\t"                      /* int(y * log2(x)) */
  37      "fxch  %%st(1)\n\t"
  38      "fsub      %%st(1),%%st\n\t"       /* fract(y * log2(x)) */
  39      "f2xm1\n\t"                        /* 2^(fract(y * log2(x))) - 1 */
  40      : "=t" (__value), "=u" (__exponent) :  "0" (__x), "1" (__y));
  41   __value += 1.0;
  42   __asm __volatile__
  43     ("fscale"
  44      : "=t" (__value) : "0" (__value), "u" (__exponent));
  45   return __value;
  46 }
  47
  48 const double E1 = 2.71828182845904523536028747135;
  49
  50 double fact (double x)
  51 {
  52   double corr;
  53   corr = 1.0;
  54   return corr * mypow(x/E1, x);
  55 }
  56
  57 int main ()
  58 {
  59   double y, z;
  60
  61   y = fact (46.2);
  62   z = mypow (46.2/E1, 46.2);
  63
  64 #if 0
  65   printf ("%26.19e, %26.19e\n", y, z);
  66 #endif
  67
  68   if (y > z)
  69     y -= z;
  70   else
  71     y = z - y;
  72
  73   y /= z;
  74   if (y > 0.1)
  75     abort ();
  76
  77   return 0;
  78 }