data CallCtxt = BoringCtxt
- | ArgCtxt Bool -- We're somewhere in the RHS of function with rules
- -- => be keener to inline
- Int -- We *are* the argument of a function with this arg discount
- -- => be keener to inline
- -- INVARIANT: ArgCtxt False 0 ==> BoringCtxt
+ | ArgCtxt -- We are somewhere in the argument of a function
+ Bool -- True <=> we're somewhere in the RHS of function with rules
+ -- False <=> we *are* the argument of a function with non-zero
+ -- arg discount
+ -- OR
+ -- we *are* the RHS of a let Note [RHS of lets]
+ -- In both cases, be a little keener to inline
| ValAppCtxt -- We're applied to at least one value arg
-- This arises when we have ((f x |> co) y)
-- that decomposes its scrutinee
instance Outputable CallCtxt where
- ppr BoringCtxt = ptext (sLit "BoringCtxt")
- ppr (ArgCtxt rules disc) = ptext (sLit "ArgCtxt") <> ppr (rules,disc)
- ppr CaseCtxt = ptext (sLit "CaseCtxt")
- ppr ValAppCtxt = ptext (sLit "ValAppCtxt")
+ ppr BoringCtxt = ptext (sLit "BoringCtxt")
+ ppr (ArgCtxt rules) = ptext (sLit "ArgCtxt") <+> ppr rules
+ ppr CaseCtxt = ptext (sLit "CaseCtxt")
+ ppr ValAppCtxt = ptext (sLit "ValAppCtxt")
callSiteInline dflags active_inline id lone_variable arg_infos cont_info
= let
}
\end{code}
+Note [RHS of lets]
+~~~~~~~~~~~~~~~~~~
+Be a tiny bit keener to inline in the RHS of a let, because that might
+lead to good thing later
+ f y = (y,y,y)
+ g y = let x = f y in ...(case x of (a,b,c) -> ...) ...
+We'd inline 'f' if the call was in a case context, and it kind-of-is,
+only we can't see it. So we treat the RHS of a let as not-totally-boring.
+
Note [Unsaturated applications]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When a call is not saturated, we *still* inline if one of the
slow-down). The motivation was test eyeball/inline1.hs; but that seems
to work ok now.
+NOTE: arguably, we should inline in ArgCtxt only if the result of the
+call is at least CONLIKE. At least for the cases where we use ArgCtxt
+for the RHS of a 'let', we only profit from the inlining if we get a
+CONLIKE thing (modulo lets).
+
Note [Lone variables]
~~~~~~~~~~~~~~~~~~~~~
The "lone-variable" case is important. I spent ages messing about
SimplCont(..), DupFlag(..), ArgInfo(..),
contIsDupable, contResultType, contIsTrivial, contArgs, dropArgs,
countValArgs, countArgs,
- mkBoringStop, mkLazyArgStop, contIsRhsOrArg,
+ mkBoringStop, mkRhsStop, mkLazyArgStop, contIsRhsOrArg,
interestingCallContext,
interestingArg, mkArgInfo,
mkBoringStop :: SimplCont
mkBoringStop = Stop BoringCtxt
+mkRhsStop :: SimplCont -- See Note [RHS of lets] in CoreUnfold
+mkRhsStop = Stop (ArgCtxt False)
+
mkLazyArgStop :: CallCtxt -> SimplCont
mkLazyArgStop cci = Stop cci
where
interesting (Select _ bndr _ _ _)
| isDeadBinder bndr = CaseCtxt
- | otherwise = ArgCtxt False 2 -- If the binder is used, this
+ | otherwise = ArgCtxt False -- If the binder is used, this
-- is like a strict let
+ -- See Note [RHS of lets] in CoreUnfold
interesting (ApplyTo _ arg _ cont)
| isTypeArg arg = interesting cont
go (CoerceIt _ c) = go c
go (Stop cci) = interesting cci
- interesting (ArgCtxt rules _) = rules
- interesting _ = False
+ interesting (ArgCtxt rules) = rules
+ interesting _ = False
\end{code}
-- See Note [Floating and type abstraction] in SimplUtils
-- Simplify the RHS
- ; (body_env1, body1) <- simplExprF body_env body mkBoringStop
-
+ ; (body_env1, body1) <- simplExprF body_env body mkRhsStop
-- ANF-ise a constructor or PAP rhs
; (body_env2, body2) <- prepareRhs body_env1 body1
; rebuildCall env (fun `App` arg') arg_info' cont }
where
arg_info' = ArgInfo { ai_rules = has_rules, ai_strs = strs, ai_discs = discs }
- cci | has_rules || disc > 0 = ArgCtxt has_rules disc -- Be keener here
- | otherwise = BoringCtxt -- Nothing interesting
+ cci | has_rules || disc > 0 = ArgCtxt has_rules -- Be keener here
+ | otherwise = BoringCtxt -- Nothing interesting
rebuildCall env fun _ cont
= rebuild env fun cont