int
const_ok_for_arm (HOST_WIDE_INT i)
{
- int lowbit;
-
+ unsigned HOST_WIDE_INT mask = ~(unsigned HOST_WIDE_INT)0xFF;
+
/* For machines with >32 bit HOST_WIDE_INT, the bits above bit 31 must
be all zero, or all one. */
if ((i & ~(unsigned HOST_WIDE_INT) 0xffffffff) != 0
& ~(unsigned HOST_WIDE_INT) 0xffffffff)))
return FALSE;
- i &= (unsigned HOST_WIDE_INT) 0xffffffff;
-
- /* Fast return for 0 and small values. We must do this for zero, since
- the code below can't handle that one case. */
- if ((i & ~(unsigned HOST_WIDE_INT) 0xff) == 0)
+ /* Fast return for 0 and powers of 2 */
+ if ((i & (i - 1)) == 0)
return TRUE;
- /* Get the number of trailing zeros, rounded down to the nearest even
- number. */
- lowbit = (ffs ((int) i) - 1) & ~1;
-
- if ((i & ~(((unsigned HOST_WIDE_INT) 0xff) << lowbit)) == 0)
- return TRUE;
- else if (lowbit <= 4
- && ((i & ~0xc000003f) == 0
- || (i & ~0xf000000f) == 0
- || (i & ~0xfc000003) == 0))
- return TRUE;
+ do
+ {
+ if ((i & mask & (unsigned HOST_WIDE_INT) 0xffffffff) == 0)
+ return TRUE;
+ mask =
+ (mask << 2) | ((mask & (unsigned HOST_WIDE_INT) 0xffffffff)
+ >> (32 - 2)) | ~(unsigned HOST_WIDE_INT) 0xffffffff;
+ }
+ while (mask != ~(unsigned HOST_WIDE_INT) 0xFF);
return FALSE;
}