On Oct 10, 2006, at 14:58 , Jón Fairbairn wrote:
Bulat Ziganshin <[EMAIL PROTECTED]> writes:
Hello Jon,
Tuesday, October 10, 2006, 1:18:52 PM, you wrote:
Surely all but one of the comparisons is unnecessary? If you
use `compare` instead of (==) and friends, won't one do (I'm
assuming that the compiler can convert cases on LT, EQ and
GT into something sensible -- after all, wasn't that the
purpose of compare?)?
it will too smart for GHC. actual code is:
compareInt# :: Int# -> Int# -> Ordering
compareInt# x# y#
| x# <# y# = LT
| x# ==# y# = EQ
| otherwise = GT
But once that's been inlined and through whatever code
generator, what then? If it doesn't get turned into one test
on the data and conditional jumps on sign bits, something
isn't doing a thorough job...
Assuming your machine architecture supports something like condition
codes. On, e.g., the MIPS you would need to test for < and ==
separately.
-- Lennart
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