The only reason this is monadised is for the unique supply.
-Note [Don't w/w inline things (a)]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
+Note [Don't w/w INLINE things]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's very important to refrain from w/w-ing an INLINE function (ie one
with an InlineRule) because the wrapper will then overwrite the
InlineRule unfolding.
in a recursive group. It might not be the loop breaker. (We could
test for loop-breaker-hood, but I'm not sure that ever matters.)
-Note [Don't w/w inline things (b)]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-In general, we refrain from w/w-ing *small* functions, because they'll
-inline anyway. But we must take care: it may look small now, but get
-to be big later after other inling has happened. So we take the
-precaution of adding an INLINE pragma to any such functions.
-
-I made this change when I observed a big function at the end of
-compilation with a useful strictness signature but no w-w. When
-I measured it on nofib, it didn't make much difference; just a few
-percent improved allocation on one benchmark (bspt/Euclid.space).
-But nothing got worse.
-
Note [Don't w/w INLINABLE things]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If we have
because you lose the worker/wrapper stuff. But I don't see a way
to avoid that.
+Note [Don't w/w inline small non-loop-breaker things]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+In general, we refrain from w/w-ing *small* functions, which are not
+loop breakers, because they'll inline anyway. But we must take care:
+it may look small now, but get to be big later after other inlining
+has happened. So we take the precaution of adding an INLINE pragma to
+any such functions.
+
+I made this change when I observed a big function at the end of
+compilation with a useful strictness signature but no w-w. When
+I measured it on nofib, it didn't make much difference; just a few
+percent improved allocation on one benchmark (bspt/Euclid.space).
+But nothing got worse.
+
Note [Wrapper activation]
~~~~~~~~~~~~~~~~~~~~~~~~~
When should the wrapper inlining be active? It must not be active
---------------------
checkSize :: Id -> CoreExpr
-> UniqSM [(Id,CoreExpr)] -> UniqSM [(Id,CoreExpr)]
- -- See Note [Don't w/w inline things (a) and (b)]
- -- and Note [Don't w/w INLINABLE things]
checkSize fn_id rhs thing_inside
- | isStableUnfolding unfolding -- For DFuns and INLINE things, leave their
- = return [ (fn_id, rhs) ] -- unfolding unchanged; but still attach
- -- strictness info to the Id
+ | isStableUnfolding (realIdUnfolding fn_id)
+ = return [ (fn_id, rhs) ]
+ -- See Note [Don't w/w INLINABLE things]
+ -- and Note [Don't w/w INLINABLABLE things]
+ -- NB: use realIdUnfolding because we want to see the unfolding
+ -- even if it's a loop breaker!
- | certainlyWillInline unfolding
+ | certainlyWillInline (idUnfolding fn_id)
= return [ (fn_id `setIdUnfolding` inline_rule, rhs) ]
- -- Note [Don't w/w inline things (b)]
+ -- Note [Don't w/w inline small non-loop-breaker things]
+ -- NB: use idUnfolding because we don't want to apply
+ -- this criterion to a loop breaker!
| otherwise = thing_inside
where
- unfolding = realIdUnfolding fn_id -- We want to see the unfolding
- -- for loop breakers!
inline_rule = mkInlineUnfolding Nothing rhs
---------------------