lldb/test/Shell/Register/Inputs/x86-fp-read.cpp

   1 #include <cstdint>
   2
   3 struct alignas(16) float80_raw {
   4   uint64_t mantissa;
   5   uint16_t sign_exp;
   6 };
   7
   8 int main() {
   9   float80_raw st[] = {
  10     {0x8000000000000000, 0x4000},  // +2.0
  11     {0x3f00000000000000, 0x0000},  // 1.654785e-4932 (denormal)
  12     {0x0000000000000000, 0x0000},  // +0
  13     {0x0000000000000000, 0x8000},  // -0
  14     {0x8000000000000000, 0x7fff},  // +inf
  15     {0x8000000000000000, 0xffff},  // -inf
  16     {0xc000000000000000, 0xffff},  // nan
  17     // st7 will be freed to test tag word better
  18     {0x0000000000000000, 0x0000},  // +0
  19   };
  20
  21   // unmask divide-by-zero exception
  22   uint16_t cw = 0x037b;
  23   // used as single-precision float
  24   uint32_t zero = 0;
  25
  26   asm volatile(
  27     "finit\n\t"
  28     "fldcw %1\n\t"
  29     // load on stack in reverse order to make the result easier to read
  30     "fldt 0x70(%0)\n\t"
  31     "fldt 0x60(%0)\n\t"
  32     "fldt 0x50(%0)\n\t"
  33     "fldt 0x40(%0)\n\t"
  34     "fldt 0x30(%0)\n\t"
  35     "fldt 0x20(%0)\n\t"
  36     "fldt 0x10(%0)\n\t"
  37     "fldt 0x00(%0)\n\t"
  38     // free st7
  39     "ffree %%st(7)\n\t"
  40     // this should trigger a divide-by-zero
  41     "fdivs (%2)\n\t"
  42     "int3\n\t"
  43     :
  44     : "a"(st), "m"(cw), "b"(&zero)
  45     : "st"
  46   );
  47
  48   return 0;
  49 }