gcc/testsuite/gcc.target/i386/badshift.c

   1 /* PR rtl-optimization/20532 */
   2
   3 /* { dg-do run } */
   4 /* { dg-options "-m32 -march=i386 -O1" } */
   5
   6 /* We used to optimize the DImode shift-by-32 to zero because in combine
   7    we turned:
   8
   9      (v << 31) * (v << 31)
  10
  11    into:
  12
  13      (v * (((HOST_WIDE_INT)1 << 31) + ((HOST_WIDE_INT)1 << 31)))
  14
  15    With a 32-bit HOST_WIDE_INT, the coefficient overflowed to zero.  */
  16
  17 unsigned long long int badshift(unsigned long long int v)
  18 {
  19         return v << 31 << 1;
  20 }
  21
  22 extern void abort ();
  23
  24 int main() {
  25   if (badshift (1) == 0)
  26     abort ();
  27   return 0;
  28 }