[I'm experimenting with leaving 'ok-for-speculation'
rhss in let-form right up to this point.]
-4. Ensure that lambdas only occur as the RHS of a binding
+4. Ensure that *value* lambdas only occur as the RHS of a binding
(The code generator can't deal with anything else.)
+ Type lambdas are ok, however, because the code gen discards them.
5. [Not any more; nuked Jun 2002] Do the seq/par munging.
data FloatingBind = FloatLet CoreBind
| FloatCase Id CoreExpr Bool
+ -- Invariant: the expression is not a lambda
-- The bool indicates "ok-for-speculation"
data Floats = Floats OkToSpec (OrdList FloatingBind)
(floats, expr2) <- deLamFloat expr1
return (floats, Note n expr2)
-corePrepExprFloat env (Case (Var id) bndr ty [(DEFAULT,[],expr)])
- | Just (TickBox {}) <- isTickBoxOp_maybe id = do
- expr1 <- corePrepAnExpr env expr
- (floats, expr2) <- deLamFloat expr1
- return (floats, Case (Var id) bndr ty [(DEFAULT,[],expr2)])
-
corePrepExprFloat env (Note other_note expr) = do
(floats, expr') <- corePrepExprFloat env expr
return (floats, Note other_note expr')
where
(bndrs,body) = collectBinders expr
+corePrepExprFloat env (Case (Var id) bndr ty [(DEFAULT,[],expr)])
+ | Just (TickBox {}) <- isTickBoxOp_maybe id = do
+ expr1 <- corePrepAnExpr env expr
+ (floats, expr2) <- deLamFloat expr1
+ return (floats, Case (Var id) bndr ty [(DEFAULT,[],expr2)])
+
corePrepExprFloat env (Case scrut bndr ty alts) = do
(floats1, scrut1) <- corePrepExprFloat env scrut
(floats2, scrut2) <- deLamFloat scrut1
mkBinds :: Floats -> CoreExpr -> UniqSM CoreExpr
+-- Lambdas are not allowed as the body of a 'let'
mkBinds (Floats _ binds) body
| isNilOL binds = return body
- | otherwise = do body' <- deLam body
- -- Lambdas are not allowed as the body of a 'let'
- return (foldrOL mk_bind body' binds)
+ | otherwise = do { body' <- deLam body
+ ; return (wrapBinds binds body') }
+
+wrapBinds :: OrdList FloatingBind -> CoreExpr -> CoreExpr
+wrapBinds binds body
+ = foldrOL mk_bind body binds
where
mk_bind (FloatCase bndr rhs _) body = Case rhs bndr (exprType body) [(DEFAULT, [], body)]
mk_bind (FloatLet bind) body = Let bind body
+---------------------
etaExpandRhs :: CoreBndr -> CoreExpr -> UniqSM CoreExpr
etaExpandRhs bndr rhs = do
-- Eta expand to match the arity claimed by the binder
-- and returns one that definitely isn't:
-- (\x.e) ==> let f = \x.e in f
deLam expr = do
- (floats, expr) <- deLamFloat expr
- mkBinds floats expr
+ (Floats _ binds, expr) <- deLamFloat expr
+ return (wrapBinds binds expr)
deLamFloat :: CoreExpr -> UniqSM (Floats, CoreExpr)