Hi! On Wed, Jun 10, 2020 at 09:14:07AM -0700, Carl Love wrote: > On Wed, 2020-06-10 at 10:46 -0500, will schmidt wrote: > > Compare that to the other predicates (config/rs6000/predicates.md) > > > > Those have explicit checks against both ends of the valid range of > > values. i.e. > > > > ;; Return 1 if op is a signed 5-bit constant integer. > > (define_predicate "s5bit_cint_operand" > > (and (match_code "const_int") > > (match_test "INTVAL (op) >= -16 && INTVAL (op) <= 15"))) > > Well, that is what I did originally. But if you see your comment > above, "There probably is a nicer way to write this than with big > decimal numbers." so I was trying to figure out how to do it without > using big numbers.
Big *decimal* numbers aren't great. But you could use hex :-) 2147483647 looks like it could be 0x7fffffff, but so does 2147438647, and that one is 0x7fff5037. > I seemed like shifting the value right 32 bits and > checking if the result was zero would tell us that op fits in 32-bits > but it doesn't seem to work. So, now I have conflicting feedback. :-) For signed you could do ((0x80000000 + UINTVAL (op)) >> 32) == 0 (or INTVAL even, makes no difference here), but that is much less readable :-) Maybe for signed it is neatest if you use trunc_int_for_mode for it? INTVAL (op) == INTVAL (trunc_int_for_mode (op, SImode)) (which neatly uses the _target_ SImode). trunc_int_for_mode always sign-extends; we don't have one that zero- extends afaik, but that one is much easier to write anyway: IN_RANGE (UINTVAL (op), 0, 0xffffffff) Segher
