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simplLamBndr :: SimplEnv -> Var -> SimplM (SimplEnv, Var)
-- Used for lambda binders. These sometimes have unfoldings added by
--- the worker/wrapper pass that must be preserved, becuase they can't
+-- the worker/wrapper pass that must be preserved, because they can't
-- be reconstructed from context. For example:
-- f x = case x of (a,b) -> fw a b x
-- fw a b x{=(a,b)} = ...
-- The "{=(a,b)}" is an unfolding we can't reconstruct otherwise.
simplLamBndr env bndr
- | not (isId bndr && hasSomeUnfolding old_unf) = simplBinder env bndr -- Normal case
- | otherwise = seqId id2 `seq` return (env', id2)
+ | isId bndr && hasSomeUnfolding old_unf = seqId id2 `seq` return (env2, id2) -- Special case
+ | otherwise = simplBinder env bndr -- Normal case
where
old_unf = idUnfolding bndr
- (env', id1) = substIdBndr env bndr
- id2 = id1 `setIdUnfolding` substUnfolding env old_unf
+ (env1, id1) = substIdBndr env bndr
+ id2 = id1 `setIdUnfolding` substUnfolding env old_unf
+ env2 = modifyInScope env1 id1 id2
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simplNonRecBndr :: SimplEnv -> InBndr -> SimplM (SimplEnv, OutBndr)
take advantage of the 'state hack' on the result of
(f y) :: State# -> (State#, Int) to expand the arity one more.
-There is a disadvantage though. Making the arity visible in the RHA
+There is a disadvantage though. Making the arity visible in the RHS
allows us to eta-reduce
f = \x -> f x
to
where
subst = mkCoreSubst env
old_rules = idSpecialisation in_id
- new_rules = CoreSubst.substSpec subst old_rules
+ new_rules = CoreSubst.substSpec subst out_id old_rules
final_id = out_id `setIdSpecialisation` new_rules
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