X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fprelude%2FPrimOp.lhs;h=29c5644346e8ea47e4f5b31d0d44fcf93b391776;hp=61ccc8dd4adfd339e423cb188daa82e3ed0a39e8;hb=c5b178be60a5a44abd2f4ddf8c399857678326e2;hpb=6a1fc2329366f912b6378a68b3f9876f0954de01

diff --git a/compiler/prelude/PrimOp.lhs b/compiler/prelude/PrimOp.lhs
index 61ccc8d..29c5644 100644
--- a/compiler/prelude/PrimOp.lhs
+++ b/compiler/prelude/PrimOp.lhs
@@ -18,10 +18,12 @@ module PrimOp (
 
 	tagToEnumKey,
 
-	primOpOutOfLine, primOpNeedsWrapper, 
-	primOpOkForSpeculation, primOpIsCheap, primOpIsDupable,
+        primOpOutOfLine, primOpCodeSize,
+        primOpOkForSpeculation, primOpIsCheap,
 
-	getPrimOpResultInfo,  PrimOpResultInfo(..)
+	getPrimOpResultInfo,  PrimOpResultInfo(..),
+
+        PrimCall(..)
     ) where
 
 #include "HsVersions.h"
@@ -29,17 +31,19 @@ module PrimOp (
 import TysPrim
 import TysWiredIn
 
-import NewDemand
+import Demand
 import Var		( TyVar )
 import OccName		( OccName, pprOccName, mkVarOccFS )
 import TyCon		( TyCon, isPrimTyCon, tyConPrimRep, PrimRep(..) )
 import Type		( Type, mkForAllTys, mkFunTy, mkFunTys, tyConAppTyCon,
 			  typePrimRep )
 import BasicTypes	( Arity, Boxity(..) )
+import ForeignCall	( CLabelString )
 import Unique		( Unique, mkPrimOpIdUnique )
 import Outputable
 import FastTypes
 import FastString
+import Module		( PackageId )
 \end{code}
 
 %************************************************************************
@@ -359,18 +363,23 @@ primOpIsCheap op = primOpOkForSpeculation op
 -- even if primOpIsCheap sometimes says 'True'.
 \end{code}
 
-primOpIsDupable
-~~~~~~~~~~~~~~~
-primOpIsDupable means that the use of the primop is small enough to
-duplicate into different case branches.  See CoreUtils.exprIsDupable.
+primOpCodeSize
+~~~~~~~~~~~~~~
+Gives an indication of the code size of a primop, for the purposes of
+calculating unfolding sizes; see CoreUnfold.sizeExpr.
 
 \begin{code}
-primOpIsDupable :: PrimOp -> Bool
-	-- See comments with CoreUtils.exprIsDupable
-	-- We say it's dupable it isn't implemented by a C call with a wrapper
-primOpIsDupable op = not (primOpNeedsWrapper op)
-\end{code}
+primOpCodeSize :: PrimOp -> Int
+#include "primop-code-size.hs-incl"
 
+primOpCodeSizeDefault :: Int
+primOpCodeSizeDefault = 1
+  -- CoreUnfold.primOpSize already takes into account primOpOutOfLine
+  -- and adds some further costs for the args in that case.
+
+primOpCodeSizeForeignCall :: Int
+primOpCodeSizeForeignCall = 4
+\end{code}
 
 \begin{code}
 primOpCanFail :: PrimOp -> Bool
@@ -380,19 +389,43 @@ primOpCanFail :: PrimOp -> Bool
 And some primops have side-effects and so, for example, must not be
 duplicated.
 
+This predicate means a little more than just "modifies the state of
+the world".  What it really means is "it cosumes the state on its
+input".  To see what this means, consider
+
+ let
+     t = case readMutVar# v s0 of (# s1, x #) -> (S# s1, x)
+     y = case t of (s,x) -> x
+ in
+     ... y ... y ...
+
+Now, this is part of an ST or IO thread, so we are guaranteed by
+construction that the program uses the state in a single-threaded way.
+Whenever the state resulting from the readMutVar# is demanded, the
+readMutVar# will be performed, and it will be ordered correctly with
+respect to other operations in the monad.
+
+But there's another way this could go wrong: GHC can inline t into y,
+and inline y.  Then although the original readMutVar# will still be
+correctly ordered with respect to the other operations, there will be
+one or more extra readMutVar#s performed later, possibly out-of-order.
+This really happened; see #3207.
+
+The property we need to capture about readMutVar# is that it consumes
+the State# value on its input.  We must retain the linearity of the
+State#.
+
+Our fix for this is to declare any primop that must be used linearly
+as having side-effects.  When primOpHasSideEffects is True,
+primOpOkForSpeculation will be False, and hence primOpIsCheap will
+also be False, and applications of the primop will never be
+duplicated.
+
 \begin{code}
 primOpHasSideEffects :: PrimOp -> Bool
 #include "primop-has-side-effects.hs-incl"
 \end{code}
 
-Inline primitive operations that perform calls need wrappers to save
-any live variables that are stored in caller-saves registers.
-
-\begin{code}
-primOpNeedsWrapper :: PrimOp -> Bool
-#include "primop-needs-wrapper.hs-incl"
-\end{code}
-
 \begin{code}
 primOpType :: PrimOp -> Type  -- you may want to use primOpSig instead
 primOpType op
@@ -474,3 +507,18 @@ pprPrimOp  :: PrimOp -> SDoc
 pprPrimOp other_op = pprOccName (primOpOcc other_op)
 \end{code}
 
+
+%************************************************************************
+%*									*
+\subsubsection[PrimCall]{User-imported primitive calls}
+%*									*
+%************************************************************************
+
+\begin{code}
+data PrimCall = PrimCall CLabelString PackageId
+
+instance Outputable PrimCall where
+  ppr (PrimCall lbl pkgId) 
+  	= text "__primcall" <+> ppr pkgId <+> ppr lbl
+
+\end{code}