-------------------
substInlineRuleInfo :: Subst -> InlineRuleInfo -> InlineRuleInfo
-substInlineRuleInfo subst (InlWrapper wkr)
- = case lookupIdSubst subst wkr of
- Var w1 -> InlWrapper w1
- other -> WARN( not (exprIsTrivial other), text "CoreSubst.substWorker:" <+> ppr wkr )
- InlVanilla -- Worker has got substituted away altogether
- -- (This can happen if it's trivial, via
- -- postInlineUnconditionally, hence only warning)
+substInlineRuleInfo (Subst in_scope ids _) (InlWrapper wkr)
+ | Just (Var w1) <- lookupVarEnv ids wkr = InlWrapper w1
+ | Just w1 <- lookupInScope in_scope wkr = InlWrapper w1
+ | otherwise = WARN( True, text "Interesting! CoreSubst.substWorker:" <+> ppr wkr )
+ InlVanilla -- Note [Worker inlining]
substInlineRuleInfo _ info = info
------------------
| otherwise = Type.tyVarsOfType (lookupTvSubst subst fv)
\end{code}
+Note [Worker inlining]
+~~~~~~~~~~~~~~~~~~~~~~
+A worker can get sustituted away entirely.
+ - it might be trivial
+ - it might simply be very small
+We do not treat an InlWrapper as an 'occurrence' in the occurence
+analyser, so it's possible that the worker is not even in scope any more.
+
+In all all these cases we simply drop the special case, returning to
+InlVanilla. The WARN is just so I can see if it happens a lot.
+
+
%************************************************************************
%* *
The Very Simple Optimiser