none/tests/amd64/bug132918.c

   1
   2 #include <stdio.h>
   3 #include <math.h>
   4
   5 typedef unsigned long long int ULong;
   6
   7 typedef
   8    struct { double d; int i; } Res;
   9
  10 static void do_fprem ( Res* res, double x, double y )
  11 {
  12   ULong c3210;
  13   double f64;
  14   double xx = x;
  15   double yy = y;
  16   __asm__ __volatile__(
  17      "finit\n\t"
  18      "fldl    %2\n\t"
  19      "fldl    %3\n\t"
  20      "fprem\n\t"
  21      "fstpl   %1\n\t"
  22      "movq    %%rax,%%r15\n\t"
  23      "xorq    %%rax,%%rax\n\t"
  24      "fnstsw  %%ax\n\t"
  25      "movq    %%rax,%0\n\t"
  26      "movq    %%r15,%%rax"
  27      : /*out*/ "=r" (c3210), "=m" (f64)
  28      : /*in*/  "m" (xx), "m" (yy)
  29      : /*trash*/ "r15", "rax", "%st", "%st(1)", "cc"
  30    );
  31   res->d = f64;
  32   res->i = (int)(c3210 & 0x4700); /* mask for C3,2,1,0 */
  33 }
  34
  35 static void show ( char* s, Res* res )
  36 {
  37   printf("%s -> 0x%04x %f\n", s, (int)res->i, (double)res->d);
  38 }
  39
  40 int main ( void )
  41 {
  42   Res r;
  43   int i;
  44   double theta;
  45
  46   do_fprem(&r, 10.1, 200.2); show("xx1", &r);
  47   do_fprem(&r, 20.3, 1.44);  show("xx2", &r);
  48
  49   for (i = 0; i < 20; i++) {
  50     theta = (2.0 * 3.14159) / 10.0 * (double)i;
  51     do_fprem(&r, 12.3*sin(theta), cos(theta)); show("xx", &r);
  52   }
  53
  54   return 0;
  55 }