make the smp way RTS-only, normal libraries now work with -smp

We had to bite the bullet here and add an extra word to every thunk,
to enable running ordinary libraries on SMP.  Otherwise, we would have
needed to ship an extra set of libraries with GHC 6.6 in addition to
the two sets we already ship (normal + profiled), and all Cabal
packages would have to be compiled for SMP too.  We decided it best
just to take the hit now, making SMP easily accessible to everyone in
GHC 6.6.

Incedentally, although this increases allocation by around 12% on
average, the performance hit is around 5%, and much less if your inner
loop doesn't use any laziness.

5 files changed, 24 insertions, 40 deletions

diff --git a/ghc/compiler/codeGen/CgForeignCall.hs b/ghc/compiler/codeGen/CgForeignCall.hs
index 155e30205c..e56189ae11 100644
--- a/ghc/compiler/codeGen/CgForeignCall.hs
+++ b/ghc/compiler/codeGen/CgForeignCall.hs
@@ -32,7 +32,7 @@ import MachOp
 import SMRep
 import ForeignCall
 import Constants
-import StaticFlags	( opt_SccProfilingOn, opt_SMP )
+import StaticFlags	( opt_SccProfilingOn )
 import Outputable
 
 import Monad		( when )
@@ -85,11 +85,10 @@ emitForeignCall results (CCall (CCallSpec target cconv safety)) args live
 			)
     stmtC (the_call vols)
     stmtC (CmmCall (CmmForeignCall resumeThread CCallConv) 
-			(if opt_SMP then [(CmmGlobal BaseReg, PtrHint)] else [])
-				-- Assign the result to BaseReg: we might now have
-				-- a different Capability!  Small optimisation:
-				-- only do this in SMP mode, where there are >1
-				-- Capabilities.
+			[ (CmmGlobal BaseReg, PtrHint) ]
+				-- Assign the result to BaseReg: we
+				-- might now have a different
+				-- Capability!
 			[ (CmmReg id, PtrHint) ]
 			(Just vols)
 			)
diff --git a/ghc/compiler/codeGen/CgHeapery.lhs b/ghc/compiler/codeGen/CgHeapery.lhs
index 78a6f78053..184af904df 100644
--- a/ghc/compiler/codeGen/CgHeapery.lhs
+++ b/ghc/compiler/codeGen/CgHeapery.lhs
@@ -23,7 +23,6 @@ module CgHeapery (
 
 #include "HsVersions.h"
 
-import Constants	( mIN_UPD_SIZE )
 import StgSyn		( AltType(..) )
 import CLabel		( CLabel, mkRtsCodeLabel )
 import CgUtils		( mkWordCLit, cmmRegOffW, cmmOffsetW,
@@ -212,8 +211,7 @@ mkStaticClosureFields cl_info ccs caf_refs payload
 
     padding_wds
 	| not is_caf = []
-	| otherwise  = replicate n (mkIntCLit 0) -- a bunch of 0s
-	where n = max 0 (mIN_UPD_SIZE - length payload)
+	| otherwise  = ASSERT(null payload) [mkIntCLit 0]
 
     static_link_field
 	| is_caf || staticClosureNeedsLink cl_info = [static_link_value]
diff --git a/ghc/compiler/codeGen/CgPrimOp.hs b/ghc/compiler/codeGen/CgPrimOp.hs
index 245a245cf4..7de4516af7 100644
--- a/ghc/compiler/codeGen/CgPrimOp.hs
+++ b/ghc/compiler/codeGen/CgPrimOp.hs
@@ -28,7 +28,7 @@ import SMRep
 import PrimOp		( PrimOp(..) )
 import SMRep		( tablesNextToCode )
 import Constants 	( wORD_SIZE, wORD_SIZE_IN_BITS )
-import StaticFlags	( opt_Parallel, opt_SMP )
+import StaticFlags	( opt_Parallel )
 import Outputable
 
 -- ---------------------------------------------------------------------------
@@ -113,9 +113,6 @@ emitPrimOp [res_r,res_c] IntSubCOp [aa,bb] live
 
 
 emitPrimOp [res] ParOp [arg] live
-  | not (opt_Parallel || opt_SMP)
-  = stmtC (CmmAssign res (CmmLit (mkIntCLit 1)))
-  | otherwise
   = do
 	-- for now, just implement this in a C function
 	-- later, we might want to inline it.
diff --git a/ghc/compiler/codeGen/ClosureInfo.lhs b/ghc/compiler/codeGen/ClosureInfo.lhs
index a5362e60e0..84d9dd95ef 100644
--- a/ghc/compiler/codeGen/ClosureInfo.lhs
+++ b/ghc/compiler/codeGen/ClosureInfo.lhs
@@ -61,11 +61,10 @@ import SMRep		-- all of it
 
 import CLabel
 
-import Constants	( mIN_UPD_SIZE, mIN_SIZE_NonUpdHeapObject )
+import Constants	( mIN_PAYLOAD_SIZE )
 import Packages		( isDllName, HomeModules )
 import StaticFlags	( opt_SccProfilingOn, opt_OmitBlackHoling,
-			  opt_Parallel, opt_DoTickyProfiling,
-			  opt_SMP )
+			  opt_Parallel, opt_DoTickyProfiling )
 import Id		( Id, idType, idArity, idName )
 import DataCon		( DataCon, dataConTyCon, isNullaryRepDataCon, dataConName )
 import Name		( Name, nameUnique, getOccName, getOccString )
@@ -387,16 +386,8 @@ Computing slop size.  WARNING: this looks dodgy --- it has deep
 knowledge of what the storage manager does with the various
 representations...
 
-Slop Requirements:
-
- - Updatable closures must be mIN_UPD_SIZE.
-
- - Heap-resident Closures must be mIN_SIZE_NonUpdHeapObject
-   (to make room for an StgEvacuated during GC).
-
-In SMP mode, we don't play the mIN_UPD_SIZE game.  Instead, every
-thunk gets an extra padding word in the header, which takes the
-the updated value.
+Slop Requirements: every thunk gets an extra padding word in the
+header, which takes the the updated value.
 
 \begin{code}
 slopSize cl_info = computeSlopSize payload_size cl_info
@@ -423,16 +414,14 @@ minPayloadSize smrep updatable
 	BlackHoleRep		 		-> min_upd_size
 	GenericRep _ _ _ _      | updatable     -> min_upd_size
 	GenericRep True _ _ _                   -> 0 -- static
-	GenericRep False _ _ _                  -> mIN_SIZE_NonUpdHeapObject
+	GenericRep False _ _ _                  -> mIN_PAYLOAD_SIZE
           --       ^^^^^___ dynamic
   where
-   min_upd_size
-	| opt_SMP   = ASSERT(mIN_SIZE_NonUpdHeapObject <= 
-				sIZEOF_StgSMPThunkHeader)
-		      0 	-- check that we already have enough
-				-- room for mIN_SIZE_NonUpdHeapObject,
-				-- due to the extra header word in SMP
-	| otherwise = mIN_UPD_SIZE
+   min_upd_size =
+	ASSERT(mIN_PAYLOAD_SIZE <= sIZEOF_StgSMPThunkHeader)
+	0 	-- check that we already have enough
+		-- room for mIN_SIZE_NonUpdHeapObject,
+		-- due to the extra header word in SMP
 \end{code}
 
 %************************************************************************
@@ -600,9 +589,11 @@ getCallMethod hmods name (LFThunk _ _ updatable std_form_info is_fun) n_args
 		-- is the fast-entry code]
 
   | updatable || opt_DoTickyProfiling  -- to catch double entry
-	      || opt_SMP    -- Always enter via node on SMP, since the
-			    -- thunk might have been blackholed in the 
-			    -- meantime.
+      {- OLD: || opt_SMP
+	 I decided to remove this, because in SMP mode it doesn't matter
+	 if we enter the same thunk multiple times, so the optimisation
+	 of jumping directly to the entry code is still valid.  --SDM
+	-}
   = ASSERT( n_args == 0 ) EnterIt
 
   | otherwise	-- Jump direct to code for single-entry thunks
diff --git a/ghc/compiler/codeGen/SMRep.lhs b/ghc/compiler/codeGen/SMRep.lhs
index b0b1b140f7..c807703b13 100644
--- a/ghc/compiler/codeGen/SMRep.lhs
+++ b/ghc/compiler/codeGen/SMRep.lhs
@@ -43,7 +43,7 @@ import Type		( Type, typePrimRep, PrimRep(..) )
 import TyCon		( TyCon, tyConPrimRep )
 import MachOp--		( MachRep(..), MachHint(..), wordRep )
 import StaticFlags	( opt_SccProfilingOn, opt_GranMacros,
-			  opt_Unregisterised, opt_SMP )
+			  opt_Unregisterised )
 import Constants
 import Outputable
 
@@ -289,8 +289,7 @@ arrPtrsHdrSize    = fixedHdrSize*wORD_SIZE + sIZEOF_StgMutArrPtrs_NoHdr
 -- Thunks have an extra header word on SMP, so the update doesn't 
 -- splat the payload.
 thunkHdrSize :: WordOff
-thunkHdrSize | opt_SMP 	 = fixedHdrSize + smp_hdr
-	     | otherwise = fixedHdrSize
+thunkHdrSize = fixedHdrSize + smp_hdr
 	where smp_hdr = sIZEOF_StgSMPThunkHeader `quot` wORD_SIZE
 \end{code}