#16402: GHC doesnt' notice that (narrowWordFOO (x .&. FOO)) is just `x`.
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Reporter: Fuuzetsu | Owner: (none)
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 8.6.3
Keywords: | Operating System: Unknown/Multiple
Architecture: | Type of failure: None/Unknown
Unknown/Multiple |
Test Case: | Blocked By:
Blocking: | Related Tickets:
Differential Rev(s): | Wiki Page:
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{{{#!hs
{-# OPTIONS_GHC -ddump-simpl -ddump-to-file -dhex-word-literals -O2 #-}
{-# LANGUAGE TypeApplications #-}
module NarrowWord where
import Data.Word
import Data.Bits
smallWord_foo :: Word64 -> Word64
smallWord_foo x = fromIntegral @Word16 $ fromIntegral (x .&. 0xFFFF)
smallWord_bar :: Word64 -> Word64
smallWord_bar x = fromIntegral @Word16 $ fromIntegral x
test :: Bool
test =
let w = 72430412501
in smallWord_foo w == smallWord_bar w
}}}
{{{#!hs
-- RHS size: {terms: 7, types: 3, coercions: 0, joins: 0/0}
smallWord_bar :: Word64 -> Word64
[GblId,
Arity=1,
Caf=NoCafRefs,
Str=