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Diffstat (limited to 'compiler/GHC/Builtin/PrimOps.hs')
| -rw-r--r-- | compiler/GHC/Builtin/PrimOps.hs | 698 |
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diff --git a/compiler/GHC/Builtin/PrimOps.hs b/compiler/GHC/Builtin/PrimOps.hs new file mode 100644 index 0000000000..e85c12a55d --- /dev/null +++ b/compiler/GHC/Builtin/PrimOps.hs @@ -0,0 +1,698 @@ +{- +(c) The GRASP/AQUA Project, Glasgow University, 1992-1998 + +\section[PrimOp]{Primitive operations (machine-level)} +-} + +{-# LANGUAGE CPP #-} + +module GHC.Builtin.PrimOps ( + PrimOp(..), PrimOpVecCat(..), allThePrimOps, + primOpType, primOpSig, + primOpTag, maxPrimOpTag, primOpOcc, + primOpWrapperId, + + tagToEnumKey, + + primOpOutOfLine, primOpCodeSize, + primOpOkForSpeculation, primOpOkForSideEffects, + primOpIsCheap, primOpFixity, + + getPrimOpResultInfo, isComparisonPrimOp, PrimOpResultInfo(..), + + PrimCall(..) + ) where + +#include "HsVersions.h" + +import GhcPrelude + +import GHC.Builtin.Types.Prim +import GHC.Builtin.Types + +import GHC.Cmm.Type +import GHC.Types.Demand +import GHC.Types.Id ( Id, mkVanillaGlobalWithInfo ) +import GHC.Types.Id.Info ( vanillaIdInfo, setCafInfo, CafInfo(NoCafRefs) ) +import GHC.Types.Name +import GHC.Builtin.Names ( gHC_PRIMOPWRAPPERS ) +import GHC.Core.TyCon ( TyCon, isPrimTyCon, PrimRep(..) ) +import GHC.Core.Type +import GHC.Types.RepType ( typePrimRep1, tyConPrimRep1 ) +import GHC.Types.Basic ( Arity, Fixity(..), FixityDirection(..), Boxity(..), + SourceText(..) ) +import GHC.Types.SrcLoc ( wiredInSrcSpan ) +import GHC.Types.ForeignCall ( CLabelString ) +import GHC.Types.Unique ( Unique, mkPrimOpIdUnique, mkPrimOpWrapperUnique ) +import GHC.Types.Module ( UnitId ) +import Outputable +import FastString + +{- +************************************************************************ +* * +\subsection[PrimOp-datatype]{Datatype for @PrimOp@ (an enumeration)} +* * +************************************************************************ + +These are in \tr{state-interface.verb} order. +-} + +-- supplies: +-- data PrimOp = ... +#include "primop-data-decl.hs-incl" + +-- supplies +-- primOpTag :: PrimOp -> Int +#include "primop-tag.hs-incl" +primOpTag _ = error "primOpTag: unknown primop" + + +instance Eq PrimOp where + op1 == op2 = primOpTag op1 == primOpTag op2 + +instance Ord PrimOp where + op1 < op2 = primOpTag op1 < primOpTag op2 + op1 <= op2 = primOpTag op1 <= primOpTag op2 + op1 >= op2 = primOpTag op1 >= primOpTag op2 + op1 > op2 = primOpTag op1 > primOpTag op2 + op1 `compare` op2 | op1 < op2 = LT + | op1 == op2 = EQ + | otherwise = GT + +instance Outputable PrimOp where + ppr op = pprPrimOp op + +data PrimOpVecCat = IntVec + | WordVec + | FloatVec + +-- An @Enum@-derived list would be better; meanwhile... (ToDo) + +allThePrimOps :: [PrimOp] +allThePrimOps = +#include "primop-list.hs-incl" + +tagToEnumKey :: Unique +tagToEnumKey = mkPrimOpIdUnique (primOpTag TagToEnumOp) + +{- +************************************************************************ +* * +\subsection[PrimOp-info]{The essential info about each @PrimOp@} +* * +************************************************************************ + +The @String@ in the @PrimOpInfos@ is the ``base name'' by which the user may +refer to the primitive operation. The conventional \tr{#}-for- +unboxed ops is added on later. + +The reason for the funny characters in the names is so we do not +interfere with the programmer's Haskell name spaces. + +We use @PrimKinds@ for the ``type'' information, because they're +(slightly) more convenient to use than @TyCons@. +-} + +data PrimOpInfo + = Dyadic OccName -- string :: T -> T -> T + Type + | Monadic OccName -- string :: T -> T + Type + | Compare OccName -- string :: T -> T -> Int# + Type + | GenPrimOp OccName -- string :: \/a1..an . T1 -> .. -> Tk -> T + [TyVar] + [Type] + Type + +mkDyadic, mkMonadic, mkCompare :: FastString -> Type -> PrimOpInfo +mkDyadic str ty = Dyadic (mkVarOccFS str) ty +mkMonadic str ty = Monadic (mkVarOccFS str) ty +mkCompare str ty = Compare (mkVarOccFS str) ty + +mkGenPrimOp :: FastString -> [TyVar] -> [Type] -> Type -> PrimOpInfo +mkGenPrimOp str tvs tys ty = GenPrimOp (mkVarOccFS str) tvs tys ty + +{- +************************************************************************ +* * +\subsubsection{Strictness} +* * +************************************************************************ + +Not all primops are strict! +-} + +primOpStrictness :: PrimOp -> Arity -> StrictSig + -- See Demand.StrictnessInfo for discussion of what the results + -- The arity should be the arity of the primop; that's why + -- this function isn't exported. +#include "primop-strictness.hs-incl" + +{- +************************************************************************ +* * +\subsubsection{Fixity} +* * +************************************************************************ +-} + +primOpFixity :: PrimOp -> Maybe Fixity +#include "primop-fixity.hs-incl" + +{- +************************************************************************ +* * +\subsubsection[PrimOp-comparison]{PrimOpInfo basic comparison ops} +* * +************************************************************************ + +@primOpInfo@ gives all essential information (from which everything +else, notably a type, can be constructed) for each @PrimOp@. +-} + +primOpInfo :: PrimOp -> PrimOpInfo +#include "primop-primop-info.hs-incl" +primOpInfo _ = error "primOpInfo: unknown primop" + +{- +Here are a load of comments from the old primOp info: + +A @Word#@ is an unsigned @Int#@. + +@decodeFloat#@ is given w/ Integer-stuff (it's similar). + +@decodeDouble#@ is given w/ Integer-stuff (it's similar). + +Decoding of floating-point numbers is sorta Integer-related. Encoding +is done with plain ccalls now (see PrelNumExtra.hs). + +A @Weak@ Pointer is created by the @mkWeak#@ primitive: + + mkWeak# :: k -> v -> f -> State# RealWorld + -> (# State# RealWorld, Weak# v #) + +In practice, you'll use the higher-level + + data Weak v = Weak# v + mkWeak :: k -> v -> IO () -> IO (Weak v) + +The following operation dereferences a weak pointer. The weak pointer +may have been finalized, so the operation returns a result code which +must be inspected before looking at the dereferenced value. + + deRefWeak# :: Weak# v -> State# RealWorld -> + (# State# RealWorld, v, Int# #) + +Only look at v if the Int# returned is /= 0 !! + +The higher-level op is + + deRefWeak :: Weak v -> IO (Maybe v) + +Weak pointers can be finalized early by using the finalize# operation: + + finalizeWeak# :: Weak# v -> State# RealWorld -> + (# State# RealWorld, Int#, IO () #) + +The Int# returned is either + + 0 if the weak pointer has already been finalized, or it has no + finalizer (the third component is then invalid). + + 1 if the weak pointer is still alive, with the finalizer returned + as the third component. + +A {\em stable name/pointer} is an index into a table of stable name +entries. Since the garbage collector is told about stable pointers, +it is safe to pass a stable pointer to external systems such as C +routines. + +\begin{verbatim} +makeStablePtr# :: a -> State# RealWorld -> (# State# RealWorld, StablePtr# a #) +freeStablePtr :: StablePtr# a -> State# RealWorld -> State# RealWorld +deRefStablePtr# :: StablePtr# a -> State# RealWorld -> (# State# RealWorld, a #) +eqStablePtr# :: StablePtr# a -> StablePtr# a -> Int# +\end{verbatim} + +It may seem a bit surprising that @makeStablePtr#@ is a @IO@ +operation since it doesn't (directly) involve IO operations. The +reason is that if some optimisation pass decided to duplicate calls to +@makeStablePtr#@ and we only pass one of the stable pointers over, a +massive space leak can result. Putting it into the IO monad +prevents this. (Another reason for putting them in a monad is to +ensure correct sequencing wrt the side-effecting @freeStablePtr@ +operation.) + +An important property of stable pointers is that if you call +makeStablePtr# twice on the same object you get the same stable +pointer back. + +Note that we can implement @freeStablePtr#@ using @_ccall_@ (and, +besides, it's not likely to be used from Haskell) so it's not a +primop. + +Question: Why @RealWorld@ - won't any instance of @_ST@ do the job? [ADR] + +Stable Names +~~~~~~~~~~~~ + +A stable name is like a stable pointer, but with three important differences: + + (a) You can't deRef one to get back to the original object. + (b) You can convert one to an Int. + (c) You don't need to 'freeStableName' + +The existence of a stable name doesn't guarantee to keep the object it +points to alive (unlike a stable pointer), hence (a). + +Invariants: + + (a) makeStableName always returns the same value for a given + object (same as stable pointers). + + (b) if two stable names are equal, it implies that the objects + from which they were created were the same. + + (c) stableNameToInt always returns the same Int for a given + stable name. + + +These primops are pretty weird. + + tagToEnum# :: Int -> a (result type must be an enumerated type) + +The constraints aren't currently checked by the front end, but the +code generator will fall over if they aren't satisfied. + +************************************************************************ +* * + Which PrimOps are out-of-line +* * +************************************************************************ + +Some PrimOps need to be called out-of-line because they either need to +perform a heap check or they block. +-} + +primOpOutOfLine :: PrimOp -> Bool +#include "primop-out-of-line.hs-incl" + +{- +************************************************************************ +* * + Failure and side effects +* * +************************************************************************ + +Note [Checking versus non-checking primops] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + + In GHC primops break down into two classes: + + a. Checking primops behave, for instance, like division. In this + case the primop may throw an exception (e.g. division-by-zero) + and is consequently is marked with the can_fail flag described below. + The ability to fail comes at the expense of precluding some optimizations. + + b. Non-checking primops behavior, for instance, like addition. While + addition can overflow it does not produce an exception. So can_fail is + set to False, and we get more optimisation opportunities. But we must + never throw an exception, so we cannot rewrite to a call to error. + + It is important that a non-checking primop never be transformed in a way that + would cause it to bottom. Doing so would violate Core's let/app invariant + (see Note [Core let/app invariant] in GHC.Core) which is critical to + the simplifier's ability to float without fear of changing program meaning. + + +Note [PrimOp can_fail and has_side_effects] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Both can_fail and has_side_effects mean that the primop has +some effect that is not captured entirely by its result value. + +---------- has_side_effects --------------------- +A primop "has_side_effects" if it has some *write* effect, visible +elsewhere + - writing to the world (I/O) + - writing to a mutable data structure (writeIORef) + - throwing a synchronous Haskell exception + +Often such primops have a type like + State -> input -> (State, output) +so the state token guarantees ordering. In general we rely *only* on +data dependencies of the state token to enforce write-effect ordering + + * NB1: if you inline unsafePerformIO, you may end up with + side-effecting ops whose 'state' output is discarded. + And programmers may do that by hand; see #9390. + That is why we (conservatively) do not discard write-effecting + primops even if both their state and result is discarded. + + * NB2: We consider primops, such as raiseIO#, that can raise a + (Haskell) synchronous exception to "have_side_effects" but not + "can_fail". We must be careful about not discarding such things; + see the paper "A semantics for imprecise exceptions". + + * NB3: *Read* effects (like reading an IORef) don't count here, + because it doesn't matter if we don't do them, or do them more than + once. *Sequencing* is maintained by the data dependency of the state + token. + +---------- can_fail ---------------------------- +A primop "can_fail" if it can fail with an *unchecked* exception on +some elements of its input domain. Main examples: + division (fails on zero denominator) + array indexing (fails if the index is out of bounds) + +An "unchecked exception" is one that is an outright error, (not +turned into a Haskell exception,) such as seg-fault or +divide-by-zero error. Such can_fail primops are ALWAYS surrounded +with a test that checks for the bad cases, but we need to be +very careful about code motion that might move it out of +the scope of the test. + +Note [Transformations affected by can_fail and has_side_effects] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The can_fail and has_side_effects properties have the following effect +on program transformations. Summary table is followed by details. + + can_fail has_side_effects +Discard YES NO +Float in YES YES +Float out NO NO +Duplicate YES NO + +* Discarding. case (a `op` b) of _ -> rhs ===> rhs + You should not discard a has_side_effects primop; e.g. + case (writeIntArray# a i v s of (# _, _ #) -> True + Arguably you should be able to discard this, since the + returned stat token is not used, but that relies on NEVER + inlining unsafePerformIO, and programmers sometimes write + this kind of stuff by hand (#9390). So we (conservatively) + never discard a has_side_effects primop. + + However, it's fine to discard a can_fail primop. For example + case (indexIntArray# a i) of _ -> True + We can discard indexIntArray#; it has can_fail, but not + has_side_effects; see #5658 which was all about this. + Notice that indexIntArray# is (in a more general handling of + effects) read effect, but we don't care about that here, and + treat read effects as *not* has_side_effects. + + Similarly (a `/#` b) can be discarded. It can seg-fault or + cause a hardware exception, but not a synchronous Haskell + exception. + + + + Synchronous Haskell exceptions, e.g. from raiseIO#, are treated + as has_side_effects and hence are not discarded. + +* Float in. You can float a can_fail or has_side_effects primop + *inwards*, but not inside a lambda (see Duplication below). + +* Float out. You must not float a can_fail primop *outwards* lest + you escape the dynamic scope of the test. Example: + case d ># 0# of + True -> case x /# d of r -> r +# 1 + False -> 0 + Here we must not float the case outwards to give + case x/# d of r -> + case d ># 0# of + True -> r +# 1 + False -> 0 + + Nor can you float out a has_side_effects primop. For example: + if blah then case writeMutVar# v True s0 of (# s1 #) -> s1 + else s0 + Notice that s0 is mentioned in both branches of the 'if', but + only one of these two will actually be consumed. But if we + float out to + case writeMutVar# v True s0 of (# s1 #) -> + if blah then s1 else s0 + the writeMutVar will be performed in both branches, which is + utterly wrong. + +* Duplication. You cannot duplicate a has_side_effect primop. You + might wonder how this can occur given the state token threading, but + just look at Control.Monad.ST.Lazy.Imp.strictToLazy! We get + something like this + p = case readMutVar# s v of + (# s', r #) -> (S# s', r) + s' = case p of (s', r) -> s' + r = case p of (s', r) -> r + + (All these bindings are boxed.) If we inline p at its two call + sites, we get a catastrophe: because the read is performed once when + s' is demanded, and once when 'r' is demanded, which may be much + later. Utterly wrong. #3207 is real example of this happening. + + However, it's fine to duplicate a can_fail primop. That is really + the only difference between can_fail and has_side_effects. + +Note [Implementation: how can_fail/has_side_effects affect transformations] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +How do we ensure that that floating/duplication/discarding are done right +in the simplifier? + +Two main predicates on primpops test these flags: + primOpOkForSideEffects <=> not has_side_effects + primOpOkForSpeculation <=> not (has_side_effects || can_fail) + + * The "no-float-out" thing is achieved by ensuring that we never + let-bind a can_fail or has_side_effects primop. The RHS of a + let-binding (which can float in and out freely) satisfies + exprOkForSpeculation; this is the let/app invariant. And + exprOkForSpeculation is false of can_fail and has_side_effects. + + * So can_fail and has_side_effects primops will appear only as the + scrutinees of cases, and that's why the FloatIn pass is capable + of floating case bindings inwards. + + * The no-duplicate thing is done via primOpIsCheap, by making + has_side_effects things (very very very) not-cheap! +-} + +primOpHasSideEffects :: PrimOp -> Bool +#include "primop-has-side-effects.hs-incl" + +primOpCanFail :: PrimOp -> Bool +#include "primop-can-fail.hs-incl" + +primOpOkForSpeculation :: PrimOp -> Bool + -- See Note [PrimOp can_fail and has_side_effects] + -- See comments with GHC.Core.Utils.exprOkForSpeculation + -- primOpOkForSpeculation => primOpOkForSideEffects +primOpOkForSpeculation op + = primOpOkForSideEffects op + && not (primOpOutOfLine op || primOpCanFail op) + -- I think the "out of line" test is because out of line things can + -- be expensive (eg sine, cosine), and so we may not want to speculate them + +primOpOkForSideEffects :: PrimOp -> Bool +primOpOkForSideEffects op + = not (primOpHasSideEffects op) + +{- +Note [primOpIsCheap] +~~~~~~~~~~~~~~~~~~~~ + +@primOpIsCheap@, as used in GHC.Core.Opt.Simplify.Utils. For now (HACK +WARNING), we just borrow some other predicates for a +what-should-be-good-enough test. "Cheap" means willing to call it more +than once, and/or push it inside a lambda. The latter could change the +behaviour of 'seq' for primops that can fail, so we don't treat them as cheap. +-} + +primOpIsCheap :: PrimOp -> Bool +-- See Note [PrimOp can_fail and has_side_effects] +primOpIsCheap op = primOpOkForSpeculation op +-- In March 2001, we changed this to +-- primOpIsCheap op = False +-- thereby making *no* primops seem cheap. But this killed eta +-- expansion on case (x ==# y) of True -> \s -> ... +-- which is bad. In particular a loop like +-- doLoop n = loop 0 +-- where +-- loop i | i == n = return () +-- | otherwise = bar i >> loop (i+1) +-- allocated a closure every time round because it doesn't eta expand. +-- +-- The problem that originally gave rise to the change was +-- let x = a +# b *# c in x +# x +-- were we don't want to inline x. But primopIsCheap doesn't control +-- that (it's exprIsDupable that does) so the problem doesn't occur +-- even if primOpIsCheap sometimes says 'True'. + +{- +************************************************************************ +* * + PrimOp code size +* * +************************************************************************ + +primOpCodeSize +~~~~~~~~~~~~~~ +Gives an indication of the code size of a primop, for the purposes of +calculating unfolding sizes; see GHC.Core.Unfold.sizeExpr. +-} + +primOpCodeSize :: PrimOp -> Int +#include "primop-code-size.hs-incl" + +primOpCodeSizeDefault :: Int +primOpCodeSizeDefault = 1 + -- GHC.Core.Unfold.primOpSize already takes into account primOpOutOfLine + -- and adds some further costs for the args in that case. + +primOpCodeSizeForeignCall :: Int +primOpCodeSizeForeignCall = 4 + +{- +************************************************************************ +* * + PrimOp types +* * +************************************************************************ +-} + +primOpType :: PrimOp -> Type -- you may want to use primOpSig instead +primOpType op + = case primOpInfo op of + Dyadic _occ ty -> dyadic_fun_ty ty + Monadic _occ ty -> monadic_fun_ty ty + Compare _occ ty -> compare_fun_ty ty + + GenPrimOp _occ tyvars arg_tys res_ty -> + mkSpecForAllTys tyvars (mkVisFunTys arg_tys res_ty) + +primOpOcc :: PrimOp -> OccName +primOpOcc op = case primOpInfo op of + Dyadic occ _ -> occ + Monadic occ _ -> occ + Compare occ _ -> occ + GenPrimOp occ _ _ _ -> occ + +{- Note [Primop wrappers] +~~~~~~~~~~~~~~~~~~~~~~~~~ +Previously hasNoBinding would claim that PrimOpIds didn't have a curried +function definition. This caused quite some trouble as we would be forced to +eta expand unsaturated primop applications very late in the Core pipeline. Not +only would this produce unnecessary thunks, but it would also result in nasty +inconsistencies in CAFfy-ness determinations (see #16846 and +Note [CAFfyness inconsistencies due to late eta expansion] in GHC.Iface.Tidy). + +However, it was quite unnecessary for hasNoBinding to claim this; primops in +fact *do* have curried definitions which are found in GHC.PrimopWrappers, which +is auto-generated by utils/genprimops from prelude/primops.txt.pp. These wrappers +are standard Haskell functions mirroring the types of the primops they wrap. +For instance, in the case of plusInt# we would have: + + module GHC.PrimopWrappers where + import GHC.Prim as P + plusInt# a b = P.plusInt# a b + +We now take advantage of these curried definitions by letting hasNoBinding +claim that PrimOpIds have a curried definition and then rewrite any unsaturated +PrimOpId applications that we find during CoreToStg as applications of the +associated wrapper (e.g. `GHC.Prim.plusInt# 3#` will get rewritten to +`GHC.PrimopWrappers.plusInt# 3#`).` The Id of the wrapper for a primop can be +found using 'PrimOp.primOpWrapperId'. + +Nota Bene: GHC.PrimopWrappers is needed *regardless*, because it's +used by GHCi, which does not implement primops direct at all. + +-} + +-- | Returns the 'Id' of the wrapper associated with the given 'PrimOp'. +-- See Note [Primop wrappers]. +primOpWrapperId :: PrimOp -> Id +primOpWrapperId op = mkVanillaGlobalWithInfo name ty info + where + info = setCafInfo vanillaIdInfo NoCafRefs + name = mkExternalName uniq gHC_PRIMOPWRAPPERS (primOpOcc op) wiredInSrcSpan + uniq = mkPrimOpWrapperUnique (primOpTag op) + ty = primOpType op + +isComparisonPrimOp :: PrimOp -> Bool +isComparisonPrimOp op = case primOpInfo op of + Compare {} -> True + _ -> False + +-- primOpSig is like primOpType but gives the result split apart: +-- (type variables, argument types, result type) +-- It also gives arity, strictness info + +primOpSig :: PrimOp -> ([TyVar], [Type], Type, Arity, StrictSig) +primOpSig op + = (tyvars, arg_tys, res_ty, arity, primOpStrictness op arity) + where + arity = length arg_tys + (tyvars, arg_tys, res_ty) + = case (primOpInfo op) of + Monadic _occ ty -> ([], [ty], ty ) + Dyadic _occ ty -> ([], [ty,ty], ty ) + Compare _occ ty -> ([], [ty,ty], intPrimTy) + GenPrimOp _occ tyvars arg_tys res_ty -> (tyvars, arg_tys, res_ty ) + +data PrimOpResultInfo + = ReturnsPrim PrimRep + | ReturnsAlg TyCon + +-- Some PrimOps need not return a manifest primitive or algebraic value +-- (i.e. they might return a polymorphic value). These PrimOps *must* +-- be out of line, or the code generator won't work. + +getPrimOpResultInfo :: PrimOp -> PrimOpResultInfo +getPrimOpResultInfo op + = case (primOpInfo op) of + Dyadic _ ty -> ReturnsPrim (typePrimRep1 ty) + Monadic _ ty -> ReturnsPrim (typePrimRep1 ty) + Compare _ _ -> ReturnsPrim (tyConPrimRep1 intPrimTyCon) + GenPrimOp _ _ _ ty | isPrimTyCon tc -> ReturnsPrim (tyConPrimRep1 tc) + | otherwise -> ReturnsAlg tc + where + tc = tyConAppTyCon ty + -- All primops return a tycon-app result + -- The tycon can be an unboxed tuple or sum, though, + -- which gives rise to a ReturnAlg + +{- +We do not currently make use of whether primops are commutable. + +We used to try to move constants to the right hand side for strength +reduction. +-} + +{- +commutableOp :: PrimOp -> Bool +#include "primop-commutable.hs-incl" +-} + +-- Utils: + +dyadic_fun_ty, monadic_fun_ty, compare_fun_ty :: Type -> Type +dyadic_fun_ty ty = mkVisFunTys [ty, ty] ty +monadic_fun_ty ty = mkVisFunTy ty ty +compare_fun_ty ty = mkVisFunTys [ty, ty] intPrimTy + +-- Output stuff: + +pprPrimOp :: PrimOp -> SDoc +pprPrimOp other_op = pprOccName (primOpOcc other_op) + +{- +************************************************************************ +* * +\subsubsection[PrimCall]{User-imported primitive calls} +* * +************************************************************************ +-} + +data PrimCall = PrimCall CLabelString UnitId + +instance Outputable PrimCall where + ppr (PrimCall lbl pkgId) + = text "__primcall" <+> ppr pkgId <+> ppr lbl |