Commit 704913cf authored by Edward Z. Yang's avatar Edward Z. Yang

Support for noinline magic function.

Signed-off-by: default avatarEdward Z. Yang <>

Test Plan: validate

Reviewers: simonpj, austin, bgamari

Subscribers: thomie

Differential Revision:
parent e907e1f1
......@@ -31,7 +31,7 @@ module MkId (
voidPrimId, voidArgId,
nullAddrId, seqId, lazyId, lazyIdKey, runRWId,
coercionTokenId, magicDictId, coerceId,
proxyHashId, noinlineIdName,
-- Re-export error Ids
module PrelRules
......@@ -112,6 +112,9 @@ There are several reasons why an Id might appear in the wiredInIds:
(4) lazyId is wired in because the wired-in version overrides the
strictness of the version defined in GHC.Base
(5) noinlineId is wired in because when we serialize to interfaces
we may insert noinline statements.
In cases (2-4), the function has a definition in a library module, and
can be called; but the wired-in version means that the details are
never read from that module's interface file; instead, the full definition
......@@ -120,7 +123,7 @@ is right here.
wiredInIds :: [Id]
= [lazyId, dollarId, oneShotId, runRWId]
= [lazyId, dollarId, oneShotId, runRWId, noinlineId]
++ errorIds -- Defined in MkCore
++ ghcPrimIds
......@@ -1039,7 +1042,7 @@ another gun with which to shoot yourself in the foot.
lazyIdName, unsafeCoerceName, nullAddrName, seqName,
realWorldName, voidPrimIdName, coercionTokenName,
magicDictName, coerceName, proxyName, dollarName, oneShotName,
runRWName :: Name
runRWName, noinlineIdName :: Name
unsafeCoerceName = mkWiredInIdName gHC_PRIM (fsLit "unsafeCoerce#") unsafeCoerceIdKey unsafeCoerceId
nullAddrName = mkWiredInIdName gHC_PRIM (fsLit "nullAddr#") nullAddrIdKey nullAddrId
seqName = mkWiredInIdName gHC_PRIM (fsLit "seq") seqIdKey seqId
......@@ -1053,6 +1056,7 @@ proxyName = mkWiredInIdName gHC_PRIM (fsLit "proxy#") proxyHash
dollarName = mkWiredInIdName gHC_BASE (fsLit "$") dollarIdKey dollarId
oneShotName = mkWiredInIdName gHC_MAGIC (fsLit "oneShot") oneShotKey oneShotId
runRWName = mkWiredInIdName gHC_MAGIC (fsLit "runRW#") runRWKey runRWId
noinlineIdName = mkWiredInIdName gHC_MAGIC (fsLit "noinline") noinlineIdKey noinlineId
dollarId :: Id -- Note [dollarId magic]
dollarId = pcMiscPrelId dollarName ty
......@@ -1159,6 +1163,12 @@ lazyId = pcMiscPrelId lazyIdName ty info
info = noCafIdInfo
ty = mkSpecForAllTys [alphaTyVar] (mkFunTy alphaTy alphaTy)
noinlineId :: Id -- See Note [noinlineId magic]
noinlineId = pcMiscPrelId noinlineIdName ty info
info = noCafIdInfo
ty = mkSpecForAllTys [alphaTyVar] (mkFunTy alphaTy alphaTy)
oneShotId :: Id -- See Note [The oneShot function]
oneShotId = pcMiscPrelId oneShotName ty info
......@@ -1362,6 +1372,22 @@ Implementing 'lazy' is a bit tricky:
* lazyId is defined in GHC.Base, so we don't *have* to inline it. If it
appears un-applied, we'll end up just calling it.
Note [noinlineId magic]
noinline :: forall a. a -> a
'noinline' is used to make sure that a function f is never inlined,
e.g., as in 'noinline f x'. Ordinarily, the identity function with NOINLINE
could be used to achieve this effect; however, this has the unfortunate
result of leaving a (useless) call to noinline at runtime. So we have
a little bit of magic to optimize away 'noinline' after we are done
running the simplifier.
'noinline' needs to be wired-in because it gets inserted automatically
when we serialize an expression to the interface format, and we DON'T
want use its fingerprints.
Note [runRW magic]
Some definitions, for instance @runST@, must have careful control over float out
......@@ -110,6 +110,7 @@ The goal of this pass is to prepare for code generation.
aren't inlined by some caller.
9. Replace (lazy e) by e. See Note [lazyId magic] in MkId.hs
Also replace (noinline e) by e.
10. Convert (LitInteger i t) into the core representation
for the Integer i. Normally this uses mkInteger, but if
......@@ -517,7 +518,8 @@ cpeRhsE _env expr@(Lit {}) = return (emptyFloats, expr)
cpeRhsE env expr@(Var {}) = cpeApp env expr
cpeRhsE env (Var f `App` _{-type-} `App` arg)
| f `hasKey` lazyIdKey -- Replace (lazy a) by a
| f `hasKey` lazyIdKey -- Replace (lazy a) with a, and
|| f `hasKey` noinlineIdKey -- Replace (noinline a) with a
= cpeRhsE env arg -- See Note [lazyId magic] in MkId
cpeRhsE env (Var f `App` _runtimeRep `App` _type `App` arg)
......@@ -2034,8 +2034,9 @@ breakpointJumpIdKey = mkPreludeMiscIdUnique 113
breakpointCondJumpIdKey = mkPreludeMiscIdUnique 114
breakpointAutoJumpIdKey = mkPreludeMiscIdUnique 115
inlineIdKey :: Unique
inlineIdKey, noinlineIdKey :: Unique
inlineIdKey = mkPreludeMiscIdUnique 120
-- see below
mapIdKey, groupWithIdKey, dollarIdKey :: Unique
mapIdKey = mkPreludeMiscIdUnique 121
......@@ -2045,6 +2046,8 @@ dollarIdKey = mkPreludeMiscIdUnique 123
coercionTokenIdKey :: Unique
coercionTokenIdKey = mkPreludeMiscIdUnique 124
noinlineIdKey = mkPreludeMiscIdUnique 125
rationalToFloatIdKey, rationalToDoubleIdKey :: Unique
rationalToFloatIdKey = mkPreludeMiscIdUnique 130
rationalToDoubleIdKey = mkPreludeMiscIdUnique 131
......@@ -157,6 +157,9 @@ ghc-prim
- Added new ``isByteArrayPinned#`` and ``isMutableByteArrayPinned#`` operation.
- New function ``noinline`` in ``GHC.Magic`` lets you mark that a function
should not be inlined. It is optimized away after the simplifier runs.
......@@ -21,7 +21,7 @@
module GHC.Magic ( inline, lazy, oneShot, runRW# ) where
module GHC.Magic ( inline, noinline, lazy, oneShot, runRW# ) where
import GHC.Prim
import GHC.CString ()
......@@ -45,6 +45,13 @@ import GHC.CString ()
inline :: a -> a
inline x = x
-- | The call @noinline f@ arranges that 'f' will not be inlined.
-- It is removed during CorePrep so that its use imposes no overhead
-- (besides the fact that it blocks inlining.)
{-# NOINLINE noinline #-}
noinline :: a -> a
noinline x = x
-- | The 'lazy' function restrains strictness analysis a little. The
-- call @lazy e@ means the same as 'e', but 'lazy' has a magical
-- property so far as strictness analysis is concerned: it is lazy in
......@@ -241,3 +241,5 @@ test('T12076', extra_clean(['T12076a.hi', 'T12076a.o']), multimod_compile, ['T12
test('T12076lit', normal, compile, ['-O'])
test('T12076sat', normal, compile, ['-O'])
test('T12212', normal, compile, ['-O'])
test('noinline01', only_ways(['optasm']), compile, ['-ddump-stg -dsuppress-uniques -O'])
module Noinline01 where
import GHC.Magic
{-# INLINE f #-}
f x = True
g = noinline f False
==================== STG syntax: ====================
Noinline01.f [InlPrag=INLINE (sat-args=1)]
:: forall t. t -> GHC.Types.Bool
[GblId, Arity=1, Caf=NoCafRefs, Str=<L,A>, Unf=OtherCon []] =
\r [eta] GHC.Types.True [];
Noinline01.g1 :: GHC.Types.Bool -> GHC.Types.Bool
[GblId, Unf=OtherCon []] =
\u [] Noinline01.f;
Noinline01.g :: GHC.Types.Bool
[GblId] =
\u [] Noinline01.g1 GHC.Types.False;
Noinline01.$trModule2 :: GHC.Types.TrName
[GblId, Caf=NoCafRefs, Str=m1, Unf=OtherCon []] =
NO_CCS GHC.Types.TrNameS! ["main"#];
Noinline01.$trModule1 :: GHC.Types.TrName
[GblId, Caf=NoCafRefs, Str=m1, Unf=OtherCon []] =
NO_CCS GHC.Types.TrNameS! ["Noinline01"#];
Noinline01.$trModule :: GHC.Types.Module
[GblId, Caf=NoCafRefs, Str=m, Unf=OtherCon []] =
NO_CCS GHC.Types.Module! [Noinline01.$trModule2
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