prepareRhs :: SimplEnv -> OutExpr -> SimplM (SimplEnv, OutExpr)
-- Adds new floats to the env iff that allows us to return a good RHS
-prepareRhs env (Cast rhs co) -- Note [Float coersions]
+prepareRhs env (Cast rhs co) -- Note [Float coercions]
= do { (env', rhs') <- makeTrivial env rhs
; return (env', Cast rhs' co) }