codeGen/StgCmmPrim.hs

    {-# LANGUAGE CPP #-}

    ----------------------------------------------------------------------------
    --
    -- Stg to C--: primitive operations
    --
    -- (c) The University of Glasgow 2004-2006
    --
    -----------------------------------------------------------------------------

    module StgCmmPrim (
       cgOpApp,
       cgPrimOp, -- internal(ish), used by cgCase to get code for a
                 -- comparison without also turning it into a Bool.
       shouldInlinePrimOp
     ) where

    #include "HsVersions.h"

    import StgCmmLayout
    import StgCmmForeign
    import StgCmmEnv
    import StgCmmMonad
    import StgCmmUtils
    import StgCmmTicky
    import StgCmmHeap
    import StgCmmProf ( costCentreFrom, curCCS )

    import DynFlags
    import Platform
    import BasicTypes
    import BlockId
    import MkGraph
    import StgSyn
    import Cmm
    import CmmInfo
    import Type     ( Type, tyConAppTyCon )
    import TyCon
    import CLabel
    import CmmUtils
    import PrimOp
    import SMRep
    import FastString
    import Outputable
    import Util

    import Prelude hiding ((<*>))

    import Data.Bits ((.&.), bit)
    import Control.Monad (liftM, when)

    ------------------------------------------------------------------------
    --      Primitive operations and foreign calls
    ------------------------------------------------------------------------

    {- Note [Foreign call results]
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    A foreign call always returns an unboxed tuple of results, one
    of which is the state token.  This seems to happen even for pure
    calls.

    Even if we returned a single result for pure calls, it'd still be
    right to wrap it in a singleton unboxed tuple, because the result
    might be a Haskell closure pointer, we don't want to evaluate it. -}

    ----------------------------------
    cgOpApp :: StgOp        -- The op
            -> [StgArg]     -- Arguments
            -> Type         -- Result type (always an unboxed tuple)
            -> FCode ReturnKind

    -- Foreign calls
    cgOpApp (StgFCallOp fcall _) stg_args res_ty
      = cgForeignCall fcall stg_args res_ty
          -- Note [Foreign call results]

    -- tagToEnum# is special: we need to pull the constructor
    -- out of the table, and perform an appropriate return.

    cgOpApp (StgPrimOp TagToEnumOp) [arg] res_ty
      = ASSERT(isEnumerationTyCon tycon)
        do  { dflags <- getDynFlags
            ; args' <- getNonVoidArgAmodes [arg]
            ; let amode = case args' of [amode] -> amode
                                        _ -> panic "TagToEnumOp had void arg"
            ; emitReturn [tagToClosure dflags tycon amode] }
       where
              -- If you're reading this code in the attempt to figure
              -- out why the compiler panic'ed here, it is probably because
              -- you used tagToEnum# in a non-monomorphic setting, e.g.,
              --         intToTg :: Enum a => Int -> a ; intToTg (I# x#) = tagToEnum# x#
              -- That won't work.
            tycon = tyConAppTyCon res_ty

    cgOpApp (StgPrimOp primop) args res_ty = do
        dflags <- getDynFlags
        cmm_args <- getNonVoidArgAmodes args
        case shouldInlinePrimOp dflags primop cmm_args of
            Nothing -> do  -- out-of-line
              let fun = CmmLit (CmmLabel (mkRtsPrimOpLabel primop))
              emitCall (NativeNodeCall, NativeReturn) fun cmm_args

            Just f  -- inline
              | ReturnsPrim VoidRep <- result_info
              -> do f []
                    emitReturn []

              | ReturnsPrim rep <- result_info
              -> do dflags <- getDynFlags
                    res <- newTemp (primRepCmmType dflags rep)
                    f [res]
                    emitReturn [CmmReg (CmmLocal res)]

              | ReturnsAlg tycon <- result_info, isUnboxedTupleTyCon tycon
              -> do (regs, _hints) <- newUnboxedTupleRegs res_ty
                    f regs
                    emitReturn (map (CmmReg . CmmLocal) regs)

              | otherwise -> panic "cgPrimop"
              where
                 result_info = getPrimOpResultInfo primop

    cgOpApp (StgPrimCallOp primcall) args _res_ty
      = do  { cmm_args <- getNonVoidArgAmodes args
            ; let fun = CmmLit (CmmLabel (mkPrimCallLabel primcall))
            ; emitCall (NativeNodeCall, NativeReturn) fun cmm_args }

    -- | Interpret the argument as an unsigned value, assuming the value
    -- is given in two-complement form in the given width.
    --
    -- Example: @asUnsigned W64 (-1)@ is 18446744073709551615.
    --
    -- This function is used to work around the fact that many array
    -- primops take Int# arguments, but we interpret them as unsigned
    -- quantities in the code gen. This means that we have to be careful
    -- every time we work on e.g. a CmmInt literal that corresponds to the
    -- array size, as it might contain a negative Integer value if the
    -- user passed a value larger than 2^(wORD_SIZE_IN_BITS-1) as the Int#
    -- literal.
    asUnsigned :: Width -> Integer -> Integer
    asUnsigned w n = n .&. (bit (widthInBits w) - 1)

    -- TODO: Several primop implementations (e.g. 'doNewByteArrayOp') use
    --     ByteOff (or some other fixed width signed type) to represent
    --     array sizes or indices. This means that these will overflow for
    --     large enough sizes.

    -- | Decide whether an out-of-line primop should be replaced by an
    -- inline implementation. This might happen e.g. if there's enough
    -- static information, such as statically know arguments, to emit a
    -- more efficient implementation inline.
    --
    -- Returns 'Nothing' if this primop should use its out-of-line
    -- implementation (defined elsewhere) and 'Just' together with a code
    -- generating function that takes the output regs as arguments
    -- otherwise.
    shouldInlinePrimOp :: DynFlags
                       -> PrimOp     -- ^ The primop
                       -> [CmmExpr]  -- ^ The primop arguments
                       -> Maybe ([LocalReg] -> FCode ())

    shouldInlinePrimOp dflags NewByteArrayOp_Char [(CmmLit (CmmInt n w))]
      | asUnsigned w n <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> doNewByteArrayOp res (fromInteger n)

    shouldInlinePrimOp dflags NewArrayOp [(CmmLit (CmmInt n w)), init]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] ->
          doNewArrayOp res (arrPtrsRep dflags (fromInteger n)) mkMAP_DIRTY_infoLabel
          [ (mkIntExpr dflags (fromInteger n),
             fixedHdrSize dflags + oFFSET_StgMutArrPtrs_ptrs dflags)
          , (mkIntExpr dflags (nonHdrSizeW (arrPtrsRep dflags (fromInteger n))),
             fixedHdrSize dflags + oFFSET_StgMutArrPtrs_size dflags)
          ]
          (fromInteger n) init

    shouldInlinePrimOp _ CopyArrayOp
        [src, src_off, dst, dst_off, (CmmLit (CmmInt n _))] =
            Just $ \ [] -> doCopyArrayOp src src_off dst dst_off (fromInteger n)

    shouldInlinePrimOp _ CopyMutableArrayOp
        [src, src_off, dst, dst_off, (CmmLit (CmmInt n _))] =
            Just $ \ [] -> doCopyMutableArrayOp src src_off dst dst_off (fromInteger n)

    shouldInlinePrimOp _ CopyArrayArrayOp
        [src, src_off, dst, dst_off, (CmmLit (CmmInt n _))] =
            Just $ \ [] -> doCopyArrayOp src src_off dst dst_off (fromInteger n)

    shouldInlinePrimOp _ CopyMutableArrayArrayOp
        [src, src_off, dst, dst_off, (CmmLit (CmmInt n _))] =
            Just $ \ [] -> doCopyMutableArrayOp src src_off dst dst_off (fromInteger n)

    shouldInlinePrimOp dflags CloneArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneArray mkMAP_FROZEN_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags CloneMutableArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneArray mkMAP_DIRTY_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags FreezeArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneArray mkMAP_FROZEN_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags ThawArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneArray mkMAP_DIRTY_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags NewSmallArrayOp [(CmmLit (CmmInt n w)), init]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] ->
          doNewArrayOp res (smallArrPtrsRep (fromInteger n)) mkSMAP_DIRTY_infoLabel
          [ (mkIntExpr dflags (fromInteger n),
             fixedHdrSize dflags + oFFSET_StgSmallMutArrPtrs_ptrs dflags)
          ]
          (fromInteger n) init

    shouldInlinePrimOp _ CopySmallArrayOp
        [src, src_off, dst, dst_off, (CmmLit (CmmInt n _))] =
            Just $ \ [] -> doCopySmallArrayOp src src_off dst dst_off (fromInteger n)

    shouldInlinePrimOp _ CopySmallMutableArrayOp
        [src, src_off, dst, dst_off, (CmmLit (CmmInt n _))] =
            Just $ \ [] -> doCopySmallMutableArrayOp src src_off dst dst_off (fromInteger n)

    shouldInlinePrimOp dflags CloneSmallArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneSmallArray mkSMAP_FROZEN_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags CloneSmallMutableArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneSmallArray mkSMAP_DIRTY_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags FreezeSmallArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneSmallArray mkSMAP_FROZEN_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags ThawSmallArrayOp [src, src_off, (CmmLit (CmmInt n w))]
      | wordsToBytes dflags (asUnsigned w n) <= fromIntegral (maxInlineAllocSize dflags) =
          Just $ \ [res] -> emitCloneSmallArray mkSMAP_DIRTY_infoLabel res src src_off (fromInteger n)

    shouldInlinePrimOp dflags primop args
      | primOpOutOfLine primop = Nothing
      | otherwise = Just $ \ regs -> emitPrimOp dflags regs primop args

    -- TODO: Several primops, such as 'copyArray#', only have an inline
    -- implementation (below) but could possibly have both an inline
    -- implementation and an out-of-line implementation, just like
    -- 'newArray#'. This would lower the amount of code generated,
    -- hopefully without a performance impact (needs to be measured).

    ---------------------------------------------------
    cgPrimOp   :: [LocalReg]        -- where to put the results
               -> PrimOp            -- the op
               -> [StgArg]          -- arguments
               -> FCode ()

    cgPrimOp results op args
      = do dflags <- getDynFlags
           arg_exprs <- getNonVoidArgAmodes args
           emitPrimOp dflags results op arg_exprs

    ------------------------------------------------------------------------
    --      Emitting code for a primop
    ------------------------------------------------------------------------

    emitPrimOp :: DynFlags
               -> [LocalReg]        -- where to put the results
               -> PrimOp            -- the op
               -> [CmmExpr]         -- arguments
               -> FCode ()

    -- First we handle various awkward cases specially.  The remaining
    -- easy cases are then handled by translateOp, defined below.

    emitPrimOp _ [res] ParOp [arg]
      =
            -- for now, just implement this in a C function
            -- later, we might want to inline it.
        emitCCall
            [(res,NoHint)]
            (CmmLit (CmmLabel (mkForeignLabel (fsLit "newSpark") Nothing ForeignLabelInExternalPackage IsFunction)))
            [(CmmReg (CmmGlobal BaseReg), AddrHint), (arg,AddrHint)]

    emitPrimOp dflags [res] SparkOp [arg]
      = do
            -- returns the value of arg in res.  We're going to therefore
            -- refer to arg twice (once to pass to newSpark(), and once to
            -- assign to res), so put it in a temporary.
            tmp <- assignTemp arg
            tmp2 <- newTemp (bWord dflags)
            emitCCall
                [(tmp2,NoHint)]
                (CmmLit (CmmLabel (mkForeignLabel (fsLit "newSpark") Nothing ForeignLabelInExternalPackage IsFunction)))
                [(CmmReg (CmmGlobal BaseReg), AddrHint), ((CmmReg (CmmLocal tmp)), AddrHint)]
            emitAssign (CmmLocal res) (CmmReg (CmmLocal tmp))

    emitPrimOp dflags [res] GetCCSOfOp [arg]
      = emitAssign (CmmLocal res) val
      where
        val
         | gopt Opt_SccProfilingOn dflags = costCentreFrom dflags (cmmUntag dflags arg)
         | otherwise                      = CmmLit (zeroCLit dflags)

    emitPrimOp _ [res] GetCurrentCCSOp [_dummy_arg]
       = emitAssign (CmmLocal res) curCCS

    emitPrimOp dflags [res] ReadMutVarOp [mutv]
       = emitAssign (CmmLocal res) (cmmLoadIndexW dflags mutv (fixedHdrSizeW dflags) (gcWord dflags))

    emitPrimOp dflags res@[] WriteMutVarOp [mutv,var]
       = do -- Without this write barrier, other CPUs may see this pointer before
            -- the writes for the closure it points to have occurred.
            emitPrimCall res MO_WriteBarrier []
            emitStore (cmmOffsetW dflags mutv (fixedHdrSizeW dflags)) var
            emitCCall
                    [{-no results-}]
                    (CmmLit (CmmLabel mkDirty_MUT_VAR_Label))
                    [(CmmReg (CmmGlobal BaseReg), AddrHint), (mutv,AddrHint)]

    --  #define sizzeofByteArrayzh(r,a) \
    --     r = ((StgArrBytes *)(a))->bytes
    emitPrimOp dflags [res] SizeofByteArrayOp [arg]
       = emit $ mkAssign (CmmLocal res) (cmmLoadIndexW dflags arg (fixedHdrSizeW dflags) (bWord dflags))

    --  #define sizzeofMutableByteArrayzh(r,a) \
    --      r = ((StgArrBytes *)(a))->bytes
    emitPrimOp dflags [res] SizeofMutableByteArrayOp [arg]
       = emitPrimOp dflags [res] SizeofByteArrayOp [arg]

    --  #define getSizzeofMutableByteArrayzh(r,a) \
    --      r = ((StgArrBytes *)(a))->bytes
    emitPrimOp dflags [res] GetSizeofMutableByteArrayOp [arg]
       = emitAssign (CmmLocal res) (cmmLoadIndexW dflags arg (fixedHdrSizeW dflags) (bWord dflags))

    --  #define touchzh(o)                  /* nothing */
    emitPrimOp _ res@[] TouchOp args@[_arg]
       = do emitPrimCall res MO_Touch args

    --  #define byteArrayContentszh(r,a) r = BYTE_ARR_CTS(a)
    emitPrimOp dflags [res] ByteArrayContents_Char [arg]
       = emitAssign (CmmLocal res) (cmmOffsetB dflags arg (arrWordsHdrSize dflags))

    --  #define stableNameToIntzh(r,s)   (r = ((StgStableName *)s)->sn)
    emitPrimOp dflags [res] StableNameToIntOp [arg]
       = emitAssign (CmmLocal res) (cmmLoadIndexW dflags arg (fixedHdrSizeW dflags) (bWord dflags))

    --  #define eqStableNamezh(r,sn1,sn2)                                   \
    --    (r = (((StgStableName *)sn1)->sn == ((StgStableName *)sn2)->sn))
    emitPrimOp dflags [res] EqStableNameOp [arg1,arg2]
       = emitAssign (CmmLocal res) (CmmMachOp (mo_wordEq dflags) [
                                       cmmLoadIndexW dflags arg1 (fixedHdrSizeW dflags) (bWord dflags),
                                       cmmLoadIndexW dflags arg2 (fixedHdrSizeW dflags) (bWord dflags)
                             ])

    emitPrimOp dflags [res] ReallyUnsafePtrEqualityOp [arg1,arg2]
       = emitAssign (CmmLocal res) (CmmMachOp (mo_wordEq dflags) [arg1,arg2])

    --  #define addrToHValuezh(r,a) r=(P_)a
    emitPrimOp _      [res] AddrToAnyOp [arg]
       = emitAssign (CmmLocal res) arg

    --  #define hvalueToAddrzh(r, a) r=(W_)a
    emitPrimOp _      [res] AnyToAddrOp [arg]
       = emitAssign (CmmLocal res) arg

    --  #define dataToTagzh(r,a)  r=(GET_TAG(((StgClosure *)a)->header.info))
    --  Note: argument may be tagged!
    emitPrimOp dflags [res] DataToTagOp [arg]
       = emitAssign (CmmLocal res) (getConstrTag dflags (cmmUntag dflags arg))

    {- Freezing arrays-of-ptrs requires changing an info table, for the
       benefit of the generational collector.  It needs to scavenge mutable
       objects, even if they are in old space.  When they become immutable,
       they can be removed from this scavenge list.  -}

    --  #define unsafeFreezzeArrayzh(r,a)
    --      {
    --        SET_INFO((StgClosure *)a,&stg_MUT_ARR_PTRS_FROZEN0_info);
    --        r = a;
    --      }
    emitPrimOp _      [res] UnsafeFreezeArrayOp [arg]
       = emit $ catAGraphs
       [ setInfo arg (CmmLit (CmmLabel mkMAP_FROZEN0_infoLabel)),
         mkAssign (CmmLocal res) arg ]
    emitPrimOp _      [res] UnsafeFreezeArrayArrayOp [arg]
       = emit $ catAGraphs
       [ setInfo arg (CmmLit (CmmLabel mkMAP_FROZEN0_infoLabel)),
         mkAssign (CmmLocal res) arg ]
    emitPrimOp _      [res] UnsafeFreezeSmallArrayOp [arg]
       = emit $ catAGraphs
       [ setInfo arg (CmmLit (CmmLabel mkSMAP_FROZEN0_infoLabel)),
         mkAssign (CmmLocal res) arg ]

    --  #define unsafeFreezzeByteArrayzh(r,a)       r=(a)
    emitPrimOp _      [res] UnsafeFreezeByteArrayOp [arg]
       = emitAssign (CmmLocal res) arg

    -- Reading/writing pointer arrays

    emitPrimOp _      [res] ReadArrayOp  [obj,ix]    = doReadPtrArrayOp res obj ix
    emitPrimOp _      [res] IndexArrayOp [obj,ix]    = doReadPtrArrayOp res obj ix
    emitPrimOp _      []  WriteArrayOp [obj,ix,v]  = doWritePtrArrayOp obj ix v

    emitPrimOp _      [res] IndexArrayArrayOp_ByteArray         [obj,ix]   = doReadPtrArrayOp res obj ix
    emitPrimOp _      [res] IndexArrayArrayOp_ArrayArray        [obj,ix]   = doReadPtrArrayOp res obj ix
    emitPrimOp _      [res] ReadArrayArrayOp_ByteArray          [obj,ix]   = doReadPtrArrayOp res obj ix
    emitPrimOp _      [res] ReadArrayArrayOp_MutableByteArray   [obj,ix]   = doReadPtrArrayOp res obj ix
    emitPrimOp _      [res] ReadArrayArrayOp_ArrayArray         [obj,ix]   = doReadPtrArrayOp res obj ix
    emitPrimOp _      [res] ReadArrayArrayOp_MutableArrayArray  [obj,ix]   = doReadPtrArrayOp res obj ix
    emitPrimOp _      []  WriteArrayArrayOp_ByteArray         [obj,ix,v] = doWritePtrArrayOp obj ix v
    emitPrimOp _      []  WriteArrayArrayOp_MutableByteArray  [obj,ix,v] = doWritePtrArrayOp obj ix v
    emitPrimOp _      []  WriteArrayArrayOp_ArrayArray        [obj,ix,v] = doWritePtrArrayOp obj ix v
    emitPrimOp _      []  WriteArrayArrayOp_MutableArrayArray [obj,ix,v] = doWritePtrArrayOp obj ix v

    emitPrimOp _      [res] ReadSmallArrayOp  [obj,ix] = doReadSmallPtrArrayOp res obj ix
    emitPrimOp _      [res] IndexSmallArrayOp [obj,ix] = doReadSmallPtrArrayOp res obj ix
    emitPrimOp _      []  WriteSmallArrayOp [obj,ix,v] = doWriteSmallPtrArrayOp obj ix v

    -- Getting the size of pointer arrays

    emitPrimOp dflags [res] SizeofArrayOp [arg]
       = emit $ mkAssign (CmmLocal res) (cmmLoadIndexW dflags arg
        (fixedHdrSizeW dflags + bytesToWordsRoundUp dflags (oFFSET_StgMutArrPtrs_ptrs dflags))
            (bWord dflags))
    emitPrimOp dflags [res] SizeofMutableArrayOp [arg]
       = emitPrimOp dflags [res] SizeofArrayOp [arg]
    emitPrimOp dflags [res] SizeofArrayArrayOp [arg]
       = emitPrimOp dflags [res] SizeofArrayOp [arg]
    emitPrimOp dflags [res] SizeofMutableArrayArrayOp [arg]
       = emitPrimOp dflags [res] SizeofArrayOp [arg]

    emitPrimOp dflags [res] SizeofSmallArrayOp [arg] =
        emit $ mkAssign (CmmLocal res)
        (cmmLoadIndexW dflags arg
         (fixedHdrSizeW dflags + bytesToWordsRoundUp dflags (oFFSET_StgSmallMutArrPtrs_ptrs dflags))
            (bWord dflags))
    emitPrimOp dflags [res] SizeofSmallMutableArrayOp [arg] =
        emitPrimOp dflags [res] SizeofSmallArrayOp [arg]

    -- IndexXXXoffAddr

    emitPrimOp dflags res IndexOffAddrOp_Char             args = doIndexOffAddrOp   (Just (mo_u_8ToWord dflags)) b8 res args
    emitPrimOp dflags res IndexOffAddrOp_WideChar         args = doIndexOffAddrOp   (Just (mo_u_32ToWord dflags)) b32 res args
    emitPrimOp dflags res IndexOffAddrOp_Int              args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res IndexOffAddrOp_Word             args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res IndexOffAddrOp_Addr             args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp _      res IndexOffAddrOp_Float            args = doIndexOffAddrOp   Nothing f32 res args
    emitPrimOp _      res IndexOffAddrOp_Double           args = doIndexOffAddrOp   Nothing f64 res args
    emitPrimOp dflags res IndexOffAddrOp_StablePtr        args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res IndexOffAddrOp_Int8             args = doIndexOffAddrOp   (Just (mo_s_8ToWord dflags)) b8  res args
    emitPrimOp dflags res IndexOffAddrOp_Int16            args = doIndexOffAddrOp   (Just (mo_s_16ToWord dflags)) b16 res args
    emitPrimOp dflags res IndexOffAddrOp_Int32            args = doIndexOffAddrOp   (Just (mo_s_32ToWord dflags)) b32 res args
    emitPrimOp _      res IndexOffAddrOp_Int64            args = doIndexOffAddrOp   Nothing b64 res args
    emitPrimOp dflags res IndexOffAddrOp_Word8            args = doIndexOffAddrOp   (Just (mo_u_8ToWord dflags)) b8  res args
    emitPrimOp dflags res IndexOffAddrOp_Word16           args = doIndexOffAddrOp   (Just (mo_u_16ToWord dflags)) b16 res args
    emitPrimOp dflags res IndexOffAddrOp_Word32           args = doIndexOffAddrOp   (Just (mo_u_32ToWord dflags)) b32 res args
    emitPrimOp _      res IndexOffAddrOp_Word64           args = doIndexOffAddrOp   Nothing b64 res args

    -- ReadXXXoffAddr, which are identical, for our purposes, to IndexXXXoffAddr.

    emitPrimOp dflags res ReadOffAddrOp_Char             args = doIndexOffAddrOp   (Just (mo_u_8ToWord dflags)) b8 res args
    emitPrimOp dflags res ReadOffAddrOp_WideChar         args = doIndexOffAddrOp   (Just (mo_u_32ToWord dflags)) b32 res args
    emitPrimOp dflags res ReadOffAddrOp_Int              args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res ReadOffAddrOp_Word             args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res ReadOffAddrOp_Addr             args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp _      res ReadOffAddrOp_Float            args = doIndexOffAddrOp   Nothing f32 res args
    emitPrimOp _      res ReadOffAddrOp_Double           args = doIndexOffAddrOp   Nothing f64 res args
    emitPrimOp dflags res ReadOffAddrOp_StablePtr        args = doIndexOffAddrOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res ReadOffAddrOp_Int8             args = doIndexOffAddrOp   (Just (mo_s_8ToWord dflags)) b8  res args
    emitPrimOp dflags res ReadOffAddrOp_Int16            args = doIndexOffAddrOp   (Just (mo_s_16ToWord dflags)) b16 res args
    emitPrimOp dflags res ReadOffAddrOp_Int32            args = doIndexOffAddrOp   (Just (mo_s_32ToWord dflags)) b32 res args
    emitPrimOp _      res ReadOffAddrOp_Int64            args = doIndexOffAddrOp   Nothing b64 res args
    emitPrimOp dflags res ReadOffAddrOp_Word8            args = doIndexOffAddrOp   (Just (mo_u_8ToWord dflags)) b8  res args
    emitPrimOp dflags res ReadOffAddrOp_Word16           args = doIndexOffAddrOp   (Just (mo_u_16ToWord dflags)) b16 res args
    emitPrimOp dflags res ReadOffAddrOp_Word32           args = doIndexOffAddrOp   (Just (mo_u_32ToWord dflags)) b32 res args
    emitPrimOp _      res ReadOffAddrOp_Word64           args = doIndexOffAddrOp   Nothing b64 res args

    -- IndexXXXArray

    emitPrimOp dflags res IndexByteArrayOp_Char             args = doIndexByteArrayOp   (Just (mo_u_8ToWord dflags)) b8 res args
    emitPrimOp dflags res IndexByteArrayOp_WideChar         args = doIndexByteArrayOp   (Just (mo_u_32ToWord dflags)) b32 res args
    emitPrimOp dflags res IndexByteArrayOp_Int              args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res IndexByteArrayOp_Word             args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res IndexByteArrayOp_Addr             args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp _      res IndexByteArrayOp_Float            args = doIndexByteArrayOp   Nothing f32 res args
    emitPrimOp _      res IndexByteArrayOp_Double           args = doIndexByteArrayOp   Nothing f64 res args
    emitPrimOp dflags res IndexByteArrayOp_StablePtr        args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res IndexByteArrayOp_Int8             args = doIndexByteArrayOp   (Just (mo_s_8ToWord dflags)) b8  res args
    emitPrimOp dflags res IndexByteArrayOp_Int16            args = doIndexByteArrayOp   (Just (mo_s_16ToWord dflags)) b16  res args
    emitPrimOp dflags res IndexByteArrayOp_Int32            args = doIndexByteArrayOp   (Just (mo_s_32ToWord dflags)) b32  res args
    emitPrimOp _      res IndexByteArrayOp_Int64            args = doIndexByteArrayOp   Nothing b64  res args
    emitPrimOp dflags res IndexByteArrayOp_Word8            args = doIndexByteArrayOp   (Just (mo_u_8ToWord dflags)) b8  res args
    emitPrimOp dflags res IndexByteArrayOp_Word16           args = doIndexByteArrayOp   (Just (mo_u_16ToWord dflags)) b16  res args
    emitPrimOp dflags res IndexByteArrayOp_Word32           args = doIndexByteArrayOp   (Just (mo_u_32ToWord dflags)) b32  res args
    emitPrimOp _      res IndexByteArrayOp_Word64           args = doIndexByteArrayOp   Nothing b64  res args

    -- ReadXXXArray, identical to IndexXXXArray.

    emitPrimOp dflags res ReadByteArrayOp_Char             args = doIndexByteArrayOp   (Just (mo_u_8ToWord dflags)) b8 res args
    emitPrimOp dflags res ReadByteArrayOp_WideChar         args = doIndexByteArrayOp   (Just (mo_u_32ToWord dflags)) b32 res args
    emitPrimOp dflags res ReadByteArrayOp_Int              args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res ReadByteArrayOp_Word             args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res ReadByteArrayOp_Addr             args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp _      res ReadByteArrayOp_Float            args = doIndexByteArrayOp   Nothing f32 res args
    emitPrimOp _      res ReadByteArrayOp_Double           args = doIndexByteArrayOp   Nothing f64 res args
    emitPrimOp dflags res ReadByteArrayOp_StablePtr        args = doIndexByteArrayOp   Nothing (bWord dflags) res args
    emitPrimOp dflags res ReadByteArrayOp_Int8             args = doIndexByteArrayOp   (Just (mo_s_8ToWord dflags)) b8  res args
    emitPrimOp dflags res ReadByteArrayOp_Int16            args = doIndexByteArrayOp   (Just (mo_s_16ToWord dflags)) b16  res args
    emitPrimOp dflags res ReadByteArrayOp_Int32            args = doIndexByteArrayOp   (Just (mo_s_32ToWord dflags)) b32  res args
    emitPrimOp _      res ReadByteArrayOp_Int64            args = doIndexByteArrayOp   Nothing b64  res args
    emitPrimOp dflags res ReadByteArrayOp_Word8            args = doIndexByteArrayOp   (Just (mo_u_8ToWord dflags)) b8  res args
    emitPrimOp dflags res ReadByteArrayOp_Word16           args = doIndexByteArrayOp   (Just (mo_u_16ToWord dflags)) b16  res args
    emitPrimOp dflags res ReadByteArrayOp_Word32           args = doIndexByteArrayOp   (Just (mo_u_32ToWord dflags)) b32  res args
    emitPrimOp _      res ReadByteArrayOp_Word64           args = doIndexByteArrayOp   Nothing b64  res args

    -- WriteXXXoffAddr

    emitPrimOp dflags res WriteOffAddrOp_Char             args = doWriteOffAddrOp (Just (mo_WordTo8 dflags))  b8 res args
    emitPrimOp dflags res WriteOffAddrOp_WideChar         args = doWriteOffAddrOp (Just (mo_WordTo32 dflags)) b32 res args
    emitPrimOp dflags res WriteOffAddrOp_Int              args = doWriteOffAddrOp Nothing (bWord dflags) res args
    emitPrimOp dflags res WriteOffAddrOp_Word             args = doWriteOffAddrOp Nothing (bWord dflags) res args
    emitPrimOp dflags res WriteOffAddrOp_Addr             args = doWriteOffAddrOp Nothing (bWord dflags) res args
    emitPrimOp _      res WriteOffAddrOp_Float            args = doWriteOffAddrOp Nothing f32 res args
    emitPrimOp _      res WriteOffAddrOp_Double           args = doWriteOffAddrOp Nothing f64 res args
    emitPrimOp dflags res WriteOffAddrOp_StablePtr        args = doWriteOffAddrOp Nothing (bWord dflags) res args
    emitPrimOp dflags res WriteOffAddrOp_Int8             args = doWriteOffAddrOp (Just (mo_WordTo8 dflags))  b8 res args
    emitPrimOp dflags res WriteOffAddrOp_Int16            args = doWriteOffAddrOp (Just (mo_WordTo16 dflags)) b16 res args
    emitPrimOp dflags res WriteOffAddrOp_Int32            args = doWriteOffAddrOp (Just (mo_WordTo32 dflags)) b32 res args
    emitPrimOp _      res WriteOffAddrOp_Int64            args = doWriteOffAddrOp Nothing b64 res args
    emitPrimOp dflags res WriteOffAddrOp_Word8            args = doWriteOffAddrOp (Just (mo_WordTo8 dflags))  b8 res args
    emitPrimOp dflags res WriteOffAddrOp_Word16           args = doWriteOffAddrOp (Just (mo_WordTo16 dflags)) b16 res args
    emitPrimOp dflags res WriteOffAddrOp_Word32           args = doWriteOffAddrOp (Just (mo_WordTo32 dflags)) b32 res args
    emitPrimOp _      res WriteOffAddrOp_Word64           args = doWriteOffAddrOp Nothing b64 res args

    -- WriteXXXArray

    emitPrimOp dflags res WriteByteArrayOp_Char             args = doWriteByteArrayOp (Just (mo_WordTo8 dflags))  b8 res args
    emitPrimOp dflags res WriteByteArrayOp_WideChar         args = doWriteByteArrayOp (Just (mo_WordTo32 dflags)) b32 res args
    emitPrimOp dflags res WriteByteArrayOp_Int              args = doWriteByteArrayOp Nothing (bWord dflags) res args
    emitPrimOp dflags res WriteByteArrayOp_Word             args = doWriteByteArrayOp Nothing (bWord dflags) res args
    emitPrimOp dflags res WriteByteArrayOp_Addr             args = doWriteByteArrayOp Nothing (bWord dflags) res args
    emitPrimOp _      res WriteByteArrayOp_Float            args = doWriteByteArrayOp Nothing f32 res args
    emitPrimOp _      res WriteByteArrayOp_Double           args = doWriteByteArrayOp Nothing f64 res args
    emitPrimOp dflags res WriteByteArrayOp_StablePtr        args = doWriteByteArrayOp Nothing (bWord dflags) res args
    emitPrimOp dflags res WriteByteArrayOp_Int8             args = doWriteByteArrayOp (Just (mo_WordTo8 dflags))  b8 res args
    emitPrimOp dflags res WriteByteArrayOp_Int16            args = doWriteByteArrayOp (Just (mo_WordTo16 dflags)) b16 res args
    emitPrimOp dflags res WriteByteArrayOp_Int32            args = doWriteByteArrayOp (Just (mo_WordTo32 dflags)) b32 res args
    emitPrimOp _      res WriteByteArrayOp_Int64            args = doWriteByteArrayOp Nothing b64 res args
    emitPrimOp dflags res WriteByteArrayOp_Word8            args = doWriteByteArrayOp (Just (mo_WordTo8 dflags))  b8  res args
    emitPrimOp dflags res WriteByteArrayOp_Word16           args = doWriteByteArrayOp (Just (mo_WordTo16 dflags)) b16 res args
    emitPrimOp dflags res WriteByteArrayOp_Word32           args = doWriteByteArrayOp (Just (mo_WordTo32 dflags)) b32 res args
    emitPrimOp _      res WriteByteArrayOp_Word64           args = doWriteByteArrayOp Nothing b64 res args

    -- Copying and setting byte arrays
    emitPrimOp _      [] CopyByteArrayOp [src,src_off,dst,dst_off,n] =
        doCopyByteArrayOp src src_off dst dst_off n
    emitPrimOp _      [] CopyMutableByteArrayOp [src,src_off,dst,dst_off,n] =
        doCopyMutableByteArrayOp src src_off dst dst_off n
    emitPrimOp _      [] CopyByteArrayToAddrOp [src,src_off,dst,n] =
        doCopyByteArrayToAddrOp src src_off dst n
    emitPrimOp _      [] CopyMutableByteArrayToAddrOp [src,src_off,dst,n] =
        doCopyMutableByteArrayToAddrOp src src_off dst n
    emitPrimOp _      [] CopyAddrToByteArrayOp [src,dst,dst_off,n] =
        doCopyAddrToByteArrayOp src dst dst_off n
    emitPrimOp _      [] SetByteArrayOp [ba,off,len,c] =
        doSetByteArrayOp ba off len c

    emitPrimOp _      [res] BSwap16Op [w] = emitBSwapCall res w W16
    emitPrimOp _      [res] BSwap32Op [w] = emitBSwapCall res w W32
    emitPrimOp _      [res] BSwap64Op [w] = emitBSwapCall res w W64
    emitPrimOp dflags [res] BSwapOp   [w] = emitBSwapCall res w (wordWidth dflags)

    -- Population count
    emitPrimOp _      [res] PopCnt8Op  [w] = emitPopCntCall res w W8
    emitPrimOp _      [res] PopCnt16Op [w] = emitPopCntCall res w W16
    emitPrimOp _      [res] PopCnt32Op [w] = emitPopCntCall res w W32
    emitPrimOp _      [res] PopCnt64Op [w] = emitPopCntCall res w W64
    emitPrimOp dflags [res] PopCntOp   [w] = emitPopCntCall res w (wordWidth dflags)

    -- count leading zeros
    emitPrimOp _      [res] Clz8Op  [w] = emitClzCall res w W8
    emitPrimOp _      [res] Clz16Op [w] = emitClzCall res w W16
    emitPrimOp _      [res] Clz32Op [w] = emitClzCall res w W32
    emitPrimOp _      [res] Clz64Op [w] = emitClzCall res w W64
    emitPrimOp dflags [res] ClzOp   [w] = emitClzCall res w (wordWidth dflags)

    -- count trailing zeros
    emitPrimOp _      [res] Ctz8Op [w]  = emitCtzCall res w W8
    emitPrimOp _      [res] Ctz16Op [w] = emitCtzCall res w W16
    emitPrimOp _      [res] Ctz32Op [w] = emitCtzCall res w W32
    emitPrimOp _      [res] Ctz64Op [w] = emitCtzCall res w W64
    emitPrimOp dflags [res] CtzOp   [w] = emitCtzCall res w (wordWidth dflags)

    -- Unsigned int to floating point conversions
    emitPrimOp _      [res] Word2FloatOp  [w] = emitPrimCall [res]
                                                (MO_UF_Conv W32) [w]
    emitPrimOp _      [res] Word2DoubleOp [w] = emitPrimCall [res]
                                                (MO_UF_Conv W64) [w]

    -- SIMD primops
    emitPrimOp dflags [res] (VecBroadcastOp vcat n w) [e] = do
        checkVecCompatibility dflags vcat n w
        doVecPackOp (vecElemInjectCast dflags vcat w) ty zeros (replicate n e) res
      where
        zeros :: CmmExpr
        zeros = CmmLit $ CmmVec (replicate n zero)

        zero :: CmmLit
        zero = case vcat of
                 IntVec   -> CmmInt 0 w
                 WordVec  -> CmmInt 0 w
                 FloatVec -> CmmFloat 0 w

        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags [res] (VecPackOp vcat n w) es = do
        checkVecCompatibility dflags vcat n w
        when (length es /= n) $
            panic "emitPrimOp: VecPackOp has wrong number of arguments"
        doVecPackOp (vecElemInjectCast dflags vcat w) ty zeros es res
      where
        zeros :: CmmExpr
        zeros = CmmLit $ CmmVec (replicate n zero)

        zero :: CmmLit
        zero = case vcat of
                 IntVec   -> CmmInt 0 w
                 WordVec  -> CmmInt 0 w
                 FloatVec -> CmmFloat 0 w

        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecUnpackOp vcat n w) [arg] = do
        checkVecCompatibility dflags vcat n w
        when (length res /= n) $
            panic "emitPrimOp: VecUnpackOp has wrong number of results"
        doVecUnpackOp (vecElemProjectCast dflags vcat w) ty arg res
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags [res] (VecInsertOp vcat n w) [v,e,i] = do
        checkVecCompatibility dflags vcat n w
        doVecInsertOp (vecElemInjectCast dflags vcat w) ty v e i res
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecIndexByteArrayOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexByteArrayOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecReadByteArrayOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexByteArrayOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecWriteByteArrayOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doWriteByteArrayOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecIndexOffAddrOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexOffAddrOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecReadOffAddrOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexOffAddrOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecWriteOffAddrOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doWriteOffAddrOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecVmmType vcat n w

    emitPrimOp dflags res (VecIndexScalarByteArrayOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexByteArrayOpAs Nothing vecty ty res args
      where
        vecty :: CmmType
        vecty = vecVmmType vcat n w

        ty :: CmmType
        ty = vecCmmCat vcat w

    emitPrimOp dflags res (VecReadScalarByteArrayOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexByteArrayOpAs Nothing vecty ty res args
      where
        vecty :: CmmType
        vecty = vecVmmType vcat n w

        ty :: CmmType
        ty = vecCmmCat vcat w

    emitPrimOp dflags res (VecWriteScalarByteArrayOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doWriteByteArrayOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecCmmCat vcat w

    emitPrimOp dflags res (VecIndexScalarOffAddrOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexOffAddrOpAs Nothing vecty ty res args
      where
        vecty :: CmmType
        vecty = vecVmmType vcat n w

        ty :: CmmType
        ty = vecCmmCat vcat w

    emitPrimOp dflags res (VecReadScalarOffAddrOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doIndexOffAddrOpAs Nothing vecty ty res args
      where
        vecty :: CmmType
        vecty = vecVmmType vcat n w

        ty :: CmmType
        ty = vecCmmCat vcat w

    emitPrimOp dflags res (VecWriteScalarOffAddrOp vcat n w) args = do
        checkVecCompatibility dflags vcat n w
        doWriteOffAddrOp Nothing ty res args
      where
        ty :: CmmType
        ty = vecCmmCat vcat w

    -- Prefetch
    emitPrimOp _ [] PrefetchByteArrayOp3        args = doPrefetchByteArrayOp 3  args
    emitPrimOp _ [] PrefetchMutableByteArrayOp3 args = doPrefetchMutableByteArrayOp 3  args
    emitPrimOp _ [] PrefetchAddrOp3             args = doPrefetchAddrOp  3  args
    emitPrimOp _ [] PrefetchValueOp3            args = doPrefetchValueOp 3 args

    emitPrimOp _ [] PrefetchByteArrayOp2        args = doPrefetchByteArrayOp 2  args
    emitPrimOp _ [] PrefetchMutableByteArrayOp2 args = doPrefetchMutableByteArrayOp 2  args
    emitPrimOp _ [] PrefetchAddrOp2             args = doPrefetchAddrOp 2  args
    emitPrimOp _ [] PrefetchValueOp2           args = doPrefetchValueOp 2 args

    emitPrimOp _ [] PrefetchByteArrayOp1        args = doPrefetchByteArrayOp 1  args
    emitPrimOp _ [] PrefetchMutableByteArrayOp1 args = doPrefetchMutableByteArrayOp 1  args
    emitPrimOp _ [] PrefetchAddrOp1             args = doPrefetchAddrOp 1  args
    emitPrimOp _ [] PrefetchValueOp1            args = doPrefetchValueOp 1 args

    emitPrimOp _ [] PrefetchByteArrayOp0        args = doPrefetchByteArrayOp 0  args
    emitPrimOp _ [] PrefetchMutableByteArrayOp0 args = doPrefetchMutableByteArrayOp 0  args
    emitPrimOp _ [] PrefetchAddrOp0             args = doPrefetchAddrOp 0  args
    emitPrimOp _ [] PrefetchValueOp0            args = doPrefetchValueOp 0 args

    -- Atomic read-modify-write
    emitPrimOp dflags [res] FetchAddByteArrayOp_Int [mba, ix, n] =
        doAtomicRMW res AMO_Add mba ix (bWord dflags) n
    emitPrimOp dflags [res] FetchSubByteArrayOp_Int [mba, ix, n] =
        doAtomicRMW res AMO_Sub mba ix (bWord dflags) n
    emitPrimOp dflags [res] FetchAndByteArrayOp_Int [mba, ix, n] =
        doAtomicRMW res AMO_And mba ix (bWord dflags) n
    emitPrimOp dflags [res] FetchNandByteArrayOp_Int [mba, ix, n] =
        doAtomicRMW res AMO_Nand mba ix (bWord dflags) n
    emitPrimOp dflags [res] FetchOrByteArrayOp_Int [mba, ix, n] =
        doAtomicRMW res AMO_Or mba ix (bWord dflags) n
    emitPrimOp dflags [res] FetchXorByteArrayOp_Int [mba, ix, n] =
        doAtomicRMW res AMO_Xor mba ix (bWord dflags) n
    emitPrimOp dflags [res] AtomicReadByteArrayOp_Int [mba, ix] =
        doAtomicReadByteArray res mba ix (bWord dflags)
    emitPrimOp dflags [] AtomicWriteByteArrayOp_Int [mba, ix, val] =
        doAtomicWriteByteArray mba ix (bWord dflags) val
    emitPrimOp dflags [res] CasByteArrayOp_Int [mba, ix, old, new] =
        doCasByteArray res mba ix (bWord dflags) old new

    -- The rest just translate straightforwardly
    emitPrimOp dflags [res] op [arg]
       | nopOp op
       = emitAssign (CmmLocal res) arg

       | Just (mop,rep) <- narrowOp op
       = emitAssign (CmmLocal res) $
               CmmMachOp (mop rep (wordWidth dflags)) [CmmMachOp (mop (wordWidth dflags) rep) [arg]]

    emitPrimOp dflags r@[res] op args
       | Just prim <- callishOp op
       = do emitPrimCall r prim args

       | Just mop <- translateOp dflags op
       = let stmt = mkAssign (CmmLocal res) (CmmMachOp mop args) in
         emit stmt

    emitPrimOp dflags results op args
       = case callishPrimOpSupported dflags op of
              Left op   -> emit $ mkUnsafeCall (PrimTarget op) results args
              Right gen -> gen results args

    type GenericOp = [CmmFormal] -> [CmmActual] -> FCode ()

    callishPrimOpSupported :: DynFlags -> PrimOp -> Either CallishMachOp GenericOp
    callishPrimOpSupported dflags op
      = case op of
          IntQuotRemOp   | ncg && (x86ish
                                  || ppc) -> Left (MO_S_QuotRem  (wordWidth dflags))
                         | otherwise      -> Right (genericIntQuotRemOp dflags)

          WordQuotRemOp  | ncg && (x86ish
                                  || ppc) -> Left (MO_U_QuotRem  (wordWidth dflags))
                         | otherwise      -> Right (genericWordQuotRemOp dflags)

          WordQuotRem2Op | (ncg && (x86ish
                                    || ppc))
                              || llvm     -> Left (MO_U_QuotRem2 (wordWidth dflags))
                         | otherwise      -> Right (genericWordQuotRem2Op dflags)

          WordAdd2Op     | (ncg && (x86ish
                                    || ppc))
                             || llvm      -> Left (MO_Add2       (wordWidth dflags))
                         | otherwise      -> Right genericWordAdd2Op

          WordSubCOp     | (ncg && (x86ish
                                    || ppc))
                             || llvm      -> Left (MO_SubWordC   (wordWidth dflags))
                         | otherwise      -> Right genericWordSubCOp

          IntAddCOp      | (ncg && (x86ish
                                    || ppc))
                             || llvm      -> Left (MO_AddIntC    (wordWidth dflags))
                         | otherwise      -> Right genericIntAddCOp

          IntSubCOp      | (ncg && (x86ish
                                    || ppc))
                             || llvm      -> Left (MO_SubIntC    (wordWidth dflags))
                         | otherwise      -> Right genericIntSubCOp

          WordMul2Op     | ncg && (x86ish
                                   || ppc)
                             || llvm      -> Left (MO_U_Mul2     (wordWidth dflags))
                         | otherwise      -> Right genericWordMul2Op
          FloatFabsOp    | (ncg && x86ish
                                   || ppc)
                             || llvm      -> Left MO_F32_Fabs
                         | otherwise      -> Right $ genericFabsOp W32
          DoubleFabsOp   | (ncg && x86ish
                                   || ppc)
                             || llvm      -> Left MO_F64_Fabs
                         | otherwise      -> Right $ genericFabsOp W64

          _ -> pprPanic "emitPrimOp: can't translate PrimOp " (ppr op)
     where
      ncg = case hscTarget dflags of
               HscAsm -> True
               _      -> False
      llvm = case hscTarget dflags of
               HscLlvm -> True
               _       -> False
      x86ish = case platformArch (targetPlatform dflags) of
                 ArchX86    -> True
                 ArchX86_64 -> True
                 _          -> False
      ppc = case platformArch (targetPlatform dflags) of
              ArchPPC      -> True
              ArchPPC_64 _ -> True
              _            -> False

    genericIntQuotRemOp :: DynFlags -> GenericOp
    genericIntQuotRemOp dflags [res_q, res_r] [arg_x, arg_y]
       = emit $ mkAssign (CmmLocal res_q)
                  (CmmMachOp (MO_S_Quot (wordWidth dflags)) [arg_x, arg_y]) <*>
                mkAssign (CmmLocal res_r)
                  (CmmMachOp (MO_S_Rem  (wordWidth dflags)) [arg_x, arg_y])
    genericIntQuotRemOp _ _ _ = panic "genericIntQuotRemOp"

    genericWordQuotRemOp :: DynFlags -> GenericOp
    genericWordQuotRemOp dflags [res_q, res_r] [arg_x, arg_y]
        = emit $ mkAssign (CmmLocal res_q)
                   (CmmMachOp (MO_U_Quot (wordWidth dflags)) [arg_x, arg_y]) <*>
                 mkAssign (CmmLocal res_r)
                   (CmmMachOp (MO_U_Rem  (wordWidth dflags)) [arg_x, arg_y])
    genericWordQuotRemOp _ _ _ = panic "genericWordQuotRemOp"

    genericWordQuotRem2Op :: DynFlags -> GenericOp
    genericWordQuotRem2Op dflags [res_q, res_r] [arg_x_high, arg_x_low, arg_y]
        = emit =<< f (widthInBits (wordWidth dflags)) zero arg_x_high arg_x_low
        where    ty = cmmExprType dflags arg_x_high
                 shl   x i = CmmMachOp (MO_Shl   (wordWidth dflags)) [x, i]
                 shr   x i = CmmMachOp (MO_U_Shr (wordWidth dflags)) [x, i]
                 or    x y = CmmMachOp (MO_Or    (wordWidth dflags)) [x, y]
                 ge    x y = CmmMachOp (MO_U_Ge  (wordWidth dflags)) [x, y]
                 ne    x y = CmmMachOp (MO_Ne    (wordWidth dflags)) [x, y]
                 minus x y = CmmMachOp (MO_Sub   (wordWidth dflags)) [x, y]
                 times x y = CmmMachOp (MO_Mul   (wordWidth dflags)) [x, y]
                 zero   = lit 0
                 one    = lit 1
                 negone = lit (fromIntegral (widthInBits (wordWidth dflags)) - 1)
                 lit i = CmmLit (CmmInt i (wordWidth dflags))

                 f :: Int -> CmmExpr -> CmmExpr -> CmmExpr -> FCode CmmAGraph
                 f 0 acc high _ = return (mkAssign (CmmLocal res_q) acc <*>
                                          mkAssign (CmmLocal res_r) high)
                 f i acc high low =
                     do roverflowedBit <- newTemp ty
                        rhigh'         <- newTemp ty
                        rhigh''        <- newTemp ty
                        rlow'          <- newTemp ty
                        risge          <- newTemp ty
                        racc'          <- newTemp ty
                        let high'         = CmmReg (CmmLocal rhigh')
                            isge          = CmmReg (CmmLocal risge)
                            overflowedBit = CmmReg (CmmLocal roverflowedBit)
                        let this = catAGraphs
                                   [mkAssign (CmmLocal roverflowedBit)
                                              (shr high negone),
                                    mkAssign (CmmLocal rhigh')
                                              (or (shl high one) (shr low negone)),
                                    mkAssign (CmmLocal rlow')
                                              (shl low one),
                                    mkAssign (CmmLocal risge)
                                              (or (overflowedBit `ne` zero)
                                                  (high' `ge` arg_y)),
                                    mkAssign (CmmLocal rhigh'')
                                              (high' `minus` (arg_y `times` isge)),
                                    mkAssign (CmmLocal racc')
                                              (or (shl acc one) isge)]
                        rest <- f (i - 1) (CmmReg (CmmLocal racc'))
                                          (CmmReg (CmmLocal rhigh''))
                                          (CmmReg (CmmLocal rlow'))
                        return (this <*> rest)
    genericWordQuotRem2Op _ _ _ = panic "genericWordQuotRem2Op"

    genericWordAdd2Op :: GenericOp
    genericWordAdd2Op [res_h, res_l] [arg_x, arg_y]
      = do dflags <- getDynFlags
           r1 <- newTemp (cmmExprType dflags arg_x)
           r2 <- newTemp (cmmExprType dflags arg_x)
           let topHalf x = CmmMachOp (MO_U_Shr (wordWidth dflags)) [x, hww]
               toTopHalf x = CmmMachOp (MO_Shl (wordWidth dflags)) [x, hww]
               bottomHalf x = CmmMachOp (MO_And (wordWidth dflags)) [x, hwm]
               add x y = CmmMachOp (MO_Add (wordWidth dflags)) [x, y]
               or x y = CmmMachOp (MO_Or (wordWidth dflags)) [x, y]
               hww = CmmLit (CmmInt (fromIntegral (widthInBits (halfWordWidth dflags)))
                                    (wordWidth dflags))
               hwm = CmmLit (CmmInt (halfWordMask dflags) (wordWidth dflags))
           emit $ catAGraphs
              [mkAssign (CmmLocal r1)
                   (add (bottomHalf arg_x) (bottomHalf arg_y)),
               mkAssign (CmmLocal r2)
                   (add (topHalf (CmmReg (CmmLocal r1)))
                        (add (topHalf arg_x) (topHalf arg_y))),
               mkAssign (CmmLocal res_h)
                   (topHalf (CmmReg (CmmLocal r2))),
               mkAssign (CmmLocal res_l)
                   (or (toTopHalf (CmmReg (CmmLocal r2)))
                       (bottomHalf (CmmReg (CmmLocal r1))))]
    genericWordAdd2Op _ _ = panic "genericWordAdd2Op"

    genericWordSubCOp :: GenericOp
    genericWordSubCOp [res_r, res_c] [aa, bb] = do
      dflags <- getDynFlags
      emit $ catAGraphs
        [ -- Put the result into 'res_r'.
          mkAssign (CmmLocal res_r) $
            CmmMachOp (mo_wordSub dflags) [aa, bb]
          -- Set 'res_c' to 1 if 'bb > aa' and to 0 otherwise.
        , mkAssign (CmmLocal res_c) $
            CmmMachOp (mo_wordUGt dflags) [bb, aa]
        ]
    genericWordSubCOp _ _ = panic "genericWordSubCOp"

    genericIntAddCOp :: GenericOp
    genericIntAddCOp [res_r, res_c] [aa, bb]
    {-
       With some bit-twiddling, we can define int{Add,Sub}Czh portably in
       C, and without needing any comparisons.  This may not be the
       fastest way to do it - if you have better code, please send it! --SDM

       Return : r = a + b,  c = 0 if no overflow, 1 on overflow.

       We currently don't make use of the r value if c is != 0 (i.e.
       overflow), we just convert to big integers and try again.  This
       could be improved by making r and c the correct values for
       plugging into a new J#.

       { r = ((I_)(a)) + ((I_)(b));                                 \
         c = ((StgWord)(~(((I_)(a))^((I_)(b))) & (((I_)(a))^r)))    \
             >> (BITS_IN (I_) - 1);                                 \
       }
       Wading through the mass of bracketry, it seems to reduce to:
       c = ( (~(a^b)) & (a^r) ) >>unsigned (BITS_IN(I_)-1)

    -}
     = do dflags <- getDynFlags
          emit $ catAGraphs [
            mkAssign (CmmLocal res_r) (CmmMachOp (mo_wordAdd dflags) [aa,bb]),
            mkAssign (CmmLocal res_c) $
              CmmMachOp (mo_wordUShr dflags) [
                    CmmMachOp (mo_wordAnd dflags) [
                        CmmMachOp (mo_wordNot dflags) [CmmMachOp (mo_wordXor dflags) [aa,bb]],
                        CmmMachOp (mo_wordXor dflags) [aa, CmmReg (CmmLocal res_r)]
                    ],
                    mkIntExpr dflags (wORD_SIZE_IN_BITS dflags - 1)
              ]
            ]
    genericIntAddCOp _ _ = panic "genericIntAddCOp"

    genericIntSubCOp :: GenericOp
    genericIntSubCOp [res_r, res_c] [aa, bb]
    {- Similarly:
       #define subIntCzh(r,c,a,b)                                   \
       { r = ((I_)(a)) - ((I_)(b));                                 \
         c = ((StgWord)((((I_)(a))^((I_)(b))) & (((I_)(a))^r)))     \
             >> (BITS_IN (I_) - 1);                                 \
       }

       c =  ((a^b) & (a^r)) >>unsigned (BITS_IN(I_)-1)
    -}
     = do dflags <- getDynFlags
          emit $ catAGraphs [
            mkAssign (CmmLocal res_r) (CmmMachOp (mo_wordSub dflags) [aa,bb]),
            mkAssign (CmmLocal res_c) $
              CmmMachOp (mo_wordUShr dflags) [
                    CmmMachOp (mo_wordAnd dflags) [
                        CmmMachOp (mo_wordXor dflags) [aa,bb],
                        CmmMachOp (mo_wordXor dflags) [aa, CmmReg (CmmLocal res_r)]
                    ],
                    mkIntExpr dflags (wORD_SIZE_IN_BITS dflags - 1)
              ]
            ]
    genericIntSubCOp _ _ = panic "genericIntSubCOp"

    genericWordMul2Op :: GenericOp
    genericWordMul2Op [res_h, res_l] [arg_x, arg_y]
     = do dflags <- getDynFlags
          let t = cmmExprType dflags arg_x
          xlyl <- liftM CmmLocal $ newTemp t
          xlyh <- liftM CmmLocal $ newTemp t
          xhyl <- liftM CmmLocal $ newTemp t
          r    <- liftM CmmLocal $ newTemp t
          -- This generic implementation is very simple and slow. We might
          -- well be able to do better, but for now this at least works.
          let topHalf x = CmmMachOp (MO_U_Shr (wordWidth dflags)) [x, hww]
              toTopHalf x = CmmMachOp (MO_Shl (wordWidth dflags)) [x, hww]
              bottomHalf x = CmmMachOp (MO_And (wordWidth dflags)) [x, hwm]
              add x y = CmmMachOp (MO_Add (wordWidth dflags)) [x, y]
              sum = foldl1 add
              mul x y = CmmMachOp (MO_Mul (wordWidth dflags)) [x, y]
              or x y = CmmMachOp (MO_Or (wordWidth dflags)) [x, y]
              hww = CmmLit (CmmInt (fromIntegral (widthInBits (halfWordWidth dflags)))
                                   (wordWidth dflags))
              hwm = CmmLit (CmmInt (halfWordMask dflags) (wordWidth dflags))
          emit $ catAGraphs
                 [mkAssign xlyl
                      (mul (bottomHalf arg_x) (bottomHalf arg_y)),
                  mkAssign xlyh
                      (mul (bottomHalf arg_x) (topHalf arg_y)),
                  mkAssign xhyl
                      (mul (topHalf arg_x) (bottomHalf arg_y)),
                  mkAssign r
                      (sum [topHalf    (CmmReg xlyl),
                            bottomHalf (CmmReg xhyl),
                            bottomHalf (CmmReg xlyh)]),
                  mkAssign (CmmLocal res_l)
                      (or (bottomHalf (CmmReg xlyl))
                          (toTopHalf (CmmReg r))),
                  mkAssign (CmmLocal res_h)
                      (sum [mul (topHalf arg_x) (topHalf arg_y),
                            topHalf (CmmReg xhyl),
                            topHalf (CmmReg xlyh),
                            topHalf (CmmReg r)])]
    genericWordMul2Op _ _ = panic "genericWordMul2Op"

    -- This replicates what we had in libraries/base/GHC/Float.hs:
    --
    --    abs x    | x == 0    = 0 -- handles (-0.0)
    --             | x >  0    = x
    --             | otherwise = negateFloat x
    genericFabsOp :: Width -> GenericOp
    genericFabsOp w [res_r] [aa]
     = do dflags <- getDynFlags
          let zero   = CmmLit (CmmFloat 0 w)

              eq x y = CmmMachOp (MO_F_Eq w) [x, y]
              gt x y = CmmMachOp (MO_F_Gt w) [x, y]

              neg x  = CmmMachOp (MO_F_Neg w) [x]

              g1 = catAGraphs [mkAssign (CmmLocal res_r) zero]
              g2 = catAGraphs [mkAssign (CmmLocal res_r) aa]

          res_t <- CmmLocal <$> newTemp (cmmExprType dflags aa)
          let g3 = catAGraphs [mkAssign res_t aa,
                               mkAssign (CmmLocal res_r) (neg (CmmReg res_t))]

          g4 <- mkCmmIfThenElse (gt aa zero) g2 g3

          emit =<< mkCmmIfThenElse (eq aa zero) g1 g4

    genericFabsOp _ _ _ = panic "genericFabsOp"

    -- These PrimOps are NOPs in Cmm

    nopOp :: PrimOp -> Bool
    nopOp Int2WordOp     = True
    nopOp Word2IntOp     = True
    nopOp Int2AddrOp     = True
    nopOp Addr2IntOp     = True
    nopOp ChrOp          = True  -- Int# and Char# are rep'd the same
    nopOp OrdOp          = True
    nopOp _              = False

    -- These PrimOps turn into double casts

    narrowOp :: PrimOp -> Maybe (Width -> Width -> MachOp, Width)
    narrowOp Narrow8IntOp   = Just (MO_SS_Conv, W8)
    narrowOp Narrow16IntOp  = Just (MO_SS_Conv, W16)
    narrowOp Narrow32IntOp  = Just (MO_SS_Conv, W32)
    narrowOp Narrow8WordOp  = Just (MO_UU_Conv, W8)
    narrowOp Narrow16WordOp = Just (MO_UU_Conv, W16)
    narrowOp Narrow32WordOp = Just (MO_UU_Conv, W32)
    narrowOp _              = Nothing

    -- Native word signless ops

    translateOp :: DynFlags -> PrimOp -> Maybe MachOp
    translateOp dflags IntAddOp       = Just (mo_wordAdd dflags)
    translateOp dflags IntSubOp       = Just (mo_wordSub dflags)
    translateOp dflags WordAddOp      = Just (mo_wordAdd dflags)
    translateOp dflags WordSubOp      = Just (mo_wordSub dflags)
    translateOp dflags AddrAddOp      = Just (mo_wordAdd dflags)
    translateOp dflags AddrSubOp      = Just (mo_wordSub dflags)

    translateOp dflags IntEqOp        = Just (mo_wordEq dflags)
    translateOp dflags IntNeOp        = Just (mo_wordNe dflags)
    translateOp dflags WordEqOp       = Just (mo_wordEq dflags)
    translateOp dflags WordNeOp       = Just (mo_wordNe dflags)
    translateOp dflags AddrEqOp       = Just (mo_wordEq dflags)
    translateOp dflags AddrNeOp       = Just (mo_wordNe dflags)

    translateOp dflags AndOp          = Just (mo_wordAnd dflags)
    translateOp dflags OrOp           = Just (mo_wordOr dflags)
    translateOp dflags XorOp          = Just (mo_wordXor dflags)
    translateOp dflags NotOp          = Just (mo_wordNot dflags)
    translateOp dflags SllOp          = Just (mo_wordShl dflags)
    translateOp dflags SrlOp          = Just (mo_wordUShr dflags)

    translateOp dflags AddrRemOp      = Just (mo_wordURem dflags)

    -- Native word signed ops

    translateOp dflags IntMulOp        = Just (mo_wordMul dflags)
    translateOp dflags IntMulMayOfloOp = Just (MO_S_MulMayOflo (wordWidth dflags))
    translateOp dflags IntQuotOp       = Just (mo_wordSQuot dflags)
    translateOp dflags IntRemOp        = Just (mo_wordSRem dflags)
    translateOp dflags IntNegOp        = Just (mo_wordSNeg dflags)

    translateOp dflags IntGeOp        = Just (mo_wordSGe dflags)
    translateOp dflags IntLeOp        = Just (mo_wordSLe dflags)
    translateOp dflags IntGtOp        = Just (mo_wordSGt dflags)
    translateOp dflags IntLtOp        = Just (mo_wordSLt dflags)

    translateOp dflags AndIOp         = Just (mo_wordAnd dflags)
    translateOp dflags OrIOp          = Just (mo_wordOr dflags)
    translateOp dflags XorIOp         = Just (mo_wordXor dflags)
    translateOp dflags NotIOp         = Just (mo_wordNot dflags)
    translateOp dflags ISllOp         = Just (mo_wordShl dflags)
    translateOp dflags ISraOp         = Just (mo_wordSShr dflags)
    translateOp dflags ISrlOp         = Just (mo_wordUShr dflags)

    -- Native word unsigned ops

    translateOp dflags WordGeOp       = Just (mo_wordUGe dflags)
    translateOp dflags WordLeOp       = Just (mo_wordULe dflags)
    translateOp dflags WordGtOp       = Just (mo_wordUGt dflags)
    translateOp dflags WordLtOp       = Just (mo_wordULt dflags)

    translateOp dflags WordMulOp      = Just (mo_wordMul dflags)
    translateOp dflags WordQuotOp     = Just (mo_wordUQuot dflags)
    translateOp dflags WordRemOp      = Just (mo_wordURem dflags)

    translateOp dflags AddrGeOp       = Just (mo_wordUGe dflags)
    translateOp dflags AddrLeOp       = Just (mo_wordULe dflags)
    translateOp dflags AddrGtOp       = Just (mo_wordUGt dflags)
    translateOp dflags AddrLtOp       = Just (mo_wordULt dflags)

    -- Char# ops

    translateOp dflags CharEqOp       = Just (MO_Eq (wordWidth dflags))
    translateOp dflags CharNeOp       = Just (MO_Ne (wordWidth dflags))
    translateOp dflags CharGeOp       = Just (MO_U_Ge (wordWidth dflags))
    translateOp dflags CharLeOp       = Just (MO_U_Le (wordWidth dflags))
    translateOp dflags CharGtOp       = Just (MO_U_Gt (wordWidth dflags))
    translateOp dflags CharLtOp       = Just (MO_U_Lt (wordWidth dflags))

    -- Double ops

    translateOp _      DoubleEqOp     = Just (MO_F_Eq W64)
    translateOp _      DoubleNeOp     = Just (MO_F_Ne W64)
    translateOp _      DoubleGeOp     = Just (MO_F_Ge W64)
    translateOp _      DoubleLeOp     = Just (MO_F_Le W64)
    translateOp _      DoubleGtOp     = Just (MO_F_Gt W64)
    translateOp _      DoubleLtOp     = Just (MO_F_Lt W64)

    translateOp _      DoubleAddOp    = Just (MO_F_Add W64)
    translateOp _      DoubleSubOp    = Just (MO_F_Sub W64)
    translateOp _      DoubleMulOp    = Just (MO_F_Mul W64)
    translateOp _      DoubleDivOp    = Just (MO_F_Quot W64)
    translateOp _      DoubleNegOp    = Just (MO_F_Neg W64)

    -- Float ops

    translateOp _      FloatEqOp     = Just (MO_F_Eq W32)
    translateOp _      FloatNeOp     = Just (MO_F_Ne W32)
    translateOp _      FloatGeOp     = Just (MO_F_Ge W32)
    translateOp _      FloatLeOp     = Just (MO_F_Le W32)
    translateOp _      FloatGtOp     = Just (MO_F_Gt W32)
    translateOp _      FloatLtOp     = Just (MO_F_Lt W32)

    translateOp _      FloatAddOp    = Just (MO_F_Add  W32)
    translateOp _      FloatSubOp    = Just (MO_F_Sub  W32)
    translateOp _      FloatMulOp    = Just (MO_F_Mul  W32)
    translateOp _      FloatDivOp    = Just (MO_F_Quot W32)
    translateOp _      FloatNegOp    = Just (MO_F_Neg  W32)

    -- Vector ops

    translateOp _ (VecAddOp FloatVec n w) = Just (MO_VF_Add  n w)
    translateOp _ (VecSubOp FloatVec n w) = Just (MO_VF_Sub  n w)
    translateOp _ (VecMulOp FloatVec n w) = Just (MO_VF_Mul  n w)
    translateOp _ (VecDivOp FloatVec n w) = Just (MO_VF_Quot n w)
    translateOp _ (VecNegOp FloatVec n w) = Just (MO_VF_Neg  n w)

    translateOp _ (VecAddOp  IntVec n w) = Just (MO_V_Add   n w)
    translateOp _ (VecSubOp  IntVec n w) = Just (MO_V_Sub   n w)
    translateOp _ (VecMulOp  IntVec n w) = Just (MO_V_Mul   n w)
    translateOp _ (VecQuotOp IntVec n w) = Just (MO_VS_Quot n w)
    translateOp _ (VecRemOp  IntVec n w) = Just (MO_VS_Rem  n w)
    translateOp _ (VecNegOp  IntVec n w) = Just (MO_VS_Neg  n w)

    translateOp _ (VecAddOp  WordVec n w) = Just (MO_V_Add   n w)
    translateOp _ (VecSubOp  WordVec n w) = Just (MO_V_Sub   n w)
    translateOp _ (VecMulOp  WordVec n w) = Just (MO_V_Mul   n w)
    translateOp _ (VecQuotOp WordVec n w) = Just (MO_VU_Quot n w)
    translateOp _ (VecRemOp  WordVec n w) = Just (MO_VU_Rem  n w)

    -- Conversions

    translateOp dflags Int2DoubleOp   = Just (MO_SF_Conv (wordWidth dflags) W64)
    translateOp dflags Double2IntOp   = Just (MO_FS_Conv W64 (wordWidth dflags))

    translateOp dflags Int2FloatOp    = Just (MO_SF_Conv (wordWidth dflags) W32)
    translateOp dflags Float2IntOp    = Just (MO_FS_Conv W32 (wordWidth dflags))

    translateOp _      Float2DoubleOp = Just (MO_FF_Conv W32 W64)
    translateOp _      Double2FloatOp = Just (MO_FF_Conv W64 W32)

    -- Word comparisons masquerading as more exotic things.

    translateOp dflags SameMutVarOp           = Just (mo_wordEq dflags)
    translateOp dflags SameMVarOp             = Just (mo_wordEq dflags)
    translateOp dflags SameMutableArrayOp     = Just (mo_wordEq dflags)
    translateOp dflags SameMutableByteArrayOp = Just (mo_wordEq dflags)
    translateOp dflags SameMutableArrayArrayOp= Just (mo_wordEq dflags)
    translateOp dflags SameSmallMutableArrayOp= Just (mo_wordEq dflags)
    translateOp dflags SameTVarOp             = Just (mo_wordEq dflags)
    translateOp dflags EqStablePtrOp          = Just (mo_wordEq dflags)

    translateOp _      _ = Nothing

    -- These primops are implemented by CallishMachOps, because they sometimes
    -- turn into foreign calls depending on the backend.

    callishOp :: PrimOp -> Maybe CallishMachOp
    callishOp DoublePowerOp  = Just MO_F64_Pwr
    callishOp DoubleSinOp    = Just MO_F64_Sin
    callishOp DoubleCosOp    = Just MO_F64_Cos
    callishOp DoubleTanOp    = Just MO_F64_Tan
    callishOp DoubleSinhOp   = Just MO_F64_Sinh
    callishOp DoubleCoshOp   = Just MO_F64_Cosh
    callishOp DoubleTanhOp   = Just MO_F64_Tanh
    callishOp DoubleAsinOp   = Just MO_F64_Asin
    callishOp DoubleAcosOp   = Just MO_F64_Acos
    callishOp DoubleAtanOp   = Just MO_F64_Atan
    callishOp DoubleLogOp    = Just MO_F64_Log
    callishOp DoubleExpOp    = Just MO_F64_Exp
    callishOp DoubleSqrtOp   = Just MO_F64_Sqrt

    callishOp FloatPowerOp  = Just MO_F32_Pwr
    callishOp FloatSinOp    = Just MO_F32_Sin
    callishOp FloatCosOp    = Just MO_F32_Cos
    callishOp FloatTanOp    = Just MO_F32_Tan
    callishOp FloatSinhOp   = Just MO_F32_Sinh
    callishOp FloatCoshOp   = Just MO_F32_Cosh
    callishOp FloatTanhOp   = Just MO_F32_Tanh
    callishOp FloatAsinOp   = Just MO_F32_Asin
    callishOp FloatAcosOp   = Just MO_F32_Acos
    callishOp FloatAtanOp   = Just MO_F32_Atan
    callishOp FloatLogOp    = Just MO_F32_Log
    callishOp FloatExpOp    = Just MO_F32_Exp
    callishOp FloatSqrtOp   = Just MO_F32_Sqrt

    callishOp _ = Nothing

    ------------------------------------------------------------------------------
    -- Helpers for translating various minor variants of array indexing.

    doIndexOffAddrOp :: Maybe MachOp
                     -> CmmType
                     -> [LocalReg]
                     -> [CmmExpr]
                     -> FCode ()
    doIndexOffAddrOp maybe_post_read_cast rep [res] [addr,idx]
       = mkBasicIndexedRead 0 maybe_post_read_cast rep res addr rep idx
    doIndexOffAddrOp _ _ _ _
       = panic "StgCmmPrim: doIndexOffAddrOp"

    doIndexOffAddrOpAs :: Maybe MachOp
                       -> CmmType
                       -> CmmType
                       -> [LocalReg]
                       -> [CmmExpr]
                       -> FCode ()
    doIndexOffAddrOpAs maybe_post_read_cast rep idx_rep [res] [addr,idx]
       = mkBasicIndexedRead 0 maybe_post_read_cast rep res addr idx_rep idx
    doIndexOffAddrOpAs _ _ _ _ _
       = panic "StgCmmPrim: doIndexOffAddrOpAs"

    doIndexByteArrayOp :: Maybe MachOp
                       -> CmmType
                       -> [LocalReg]
                       -> [CmmExpr]
                       -> FCode ()
    doIndexByteArrayOp maybe_post_read_cast rep [res] [addr,idx]
       = do dflags <- getDynFlags
            mkBasicIndexedRead (arrWordsHdrSize dflags) maybe_post_read_cast rep res addr rep idx
    doIndexByteArrayOp _ _ _ _
       = panic "StgCmmPrim: doIndexByteArrayOp"

    doIndexByteArrayOpAs :: Maybe MachOp
                        -> CmmType
                        -> CmmType
                        -> [LocalReg]
                        -> [CmmExpr]
                        -> FCode ()
    doIndexByteArrayOpAs maybe_post_read_cast rep idx_rep [res] [addr,idx]
       = do dflags <- getDynFlags
            mkBasicIndexedRead (arrWordsHdrSize dflags) maybe_post_read_cast rep res addr idx_rep idx
    doIndexByteArrayOpAs _ _ _ _ _
       = panic "StgCmmPrim: doIndexByteArrayOpAs"

    doReadPtrArrayOp :: LocalReg
                     -> CmmExpr
                     -> CmmExpr
                     -> FCode ()
    doReadPtrArrayOp res addr idx
       = do dflags <- getDynFlags
            mkBasicIndexedRead (arrPtrsHdrSize dflags) Nothing (gcWord dflags) res addr (gcWord dflags) idx

    doWriteOffAddrOp :: Maybe MachOp
                     -> CmmType
                     -> [LocalReg]
                     -> [CmmExpr]
                     -> FCode ()
    doWriteOffAddrOp maybe_pre_write_cast idx_ty [] [addr,idx,val]
       = mkBasicIndexedWrite 0 maybe_pre_write_cast addr idx_ty idx val
    doWriteOffAddrOp _ _ _ _
       = panic "StgCmmPrim: doWriteOffAddrOp"

    doWriteByteArrayOp :: Maybe MachOp
                       -> CmmType
                       -> [LocalReg]
                       -> [CmmExpr]
                       -> FCode ()
    doWriteByteArrayOp maybe_pre_write_cast idx_ty [] [addr,idx,val]
       = do dflags <- getDynFlags
            mkBasicIndexedWrite (arrWordsHdrSize dflags) maybe_pre_write_cast addr idx_ty idx val
    doWriteByteArrayOp _ _ _ _
       = panic "StgCmmPrim: doWriteByteArrayOp"

    doWritePtrArrayOp :: CmmExpr
                      -> CmmExpr
                      -> CmmExpr
                      -> FCode ()
    doWritePtrArrayOp addr idx val
      = do dflags <- getDynFlags
           let ty = cmmExprType dflags val
           -- This write barrier is to ensure that the heap writes to the object
           -- referred to by val have happened before we write val into the array.
           -- See #12469 for details.
           emitPrimCall [] MO_WriteBarrier []
           mkBasicIndexedWrite (arrPtrsHdrSize dflags) Nothing addr ty idx val
           emit (setInfo addr (CmmLit (CmmLabel mkMAP_DIRTY_infoLabel)))
      -- the write barrier.  We must write a byte into the mark table:
      -- bits8[a + header_size + StgMutArrPtrs_size(a) + x >> N]
           emit $ mkStore (
             cmmOffsetExpr dflags
              (cmmOffsetExprW dflags (cmmOffsetB dflags addr (arrPtrsHdrSize dflags))
                             (loadArrPtrsSize dflags addr))
              (CmmMachOp (mo_wordUShr dflags) [idx,
                                               mkIntExpr dflags (mUT_ARR_PTRS_CARD_BITS dflags)])
             ) (CmmLit (CmmInt 1 W8))

    loadArrPtrsSize :: DynFlags -> CmmExpr -> CmmExpr
    loadArrPtrsSize dflags addr = CmmLoad (cmmOffsetB dflags addr off) (bWord dflags)
     where off = fixedHdrSize dflags + oFFSET_StgMutArrPtrs_ptrs dflags

    mkBasicIndexedRead :: ByteOff      -- Initial offset in bytes
                       -> Maybe MachOp -- Optional result cast
                       -> CmmType      -- Type of element we are accessing
                       -> LocalReg     -- Destination
                       -> CmmExpr      -- Base address
                       -> CmmType      -- Type of element by which we are indexing
                       -> CmmExpr      -- Index
                       -> FCode ()
    mkBasicIndexedRead off Nothing ty res base idx_ty idx
       = do dflags <- getDynFlags
            emitAssign (CmmLocal res) (cmmLoadIndexOffExpr dflags off ty base idx_ty idx)
    mkBasicIndexedRead off (Just cast) ty res base idx_ty idx
       = do dflags <- getDynFlags
            emitAssign (CmmLocal res) (CmmMachOp cast [
                                       cmmLoadIndexOffExpr dflags off ty base idx_ty idx])

    mkBasicIndexedWrite :: ByteOff      -- Initial offset in bytes
                        -> Maybe MachOp -- Optional value cast
                        -> CmmExpr      -- Base address
                        -> CmmType      -- Type of element by which we are indexing
                        -> CmmExpr      -- Index
                        -> CmmExpr      -- Value to write
                        -> FCode ()
    mkBasicIndexedWrite off Nothing base idx_ty idx val
       = do dflags <- getDynFlags
            emitStore (cmmIndexOffExpr dflags off (typeWidth idx_ty) base idx) val
    mkBasicIndexedWrite off (Just cast) base idx_ty idx val
       = mkBasicIndexedWrite off Nothing base idx_ty idx (CmmMachOp cast [val])

    -- ----------------------------------------------------------------------------
    -- Misc utils

    cmmIndexOffExpr :: DynFlags
                    -> ByteOff  -- Initial offset in bytes
                    -> Width    -- Width of element by which we are indexing
                    -> CmmExpr  -- Base address
                    -> CmmExpr  -- Index
                    -> CmmExpr
    cmmIndexOffExpr dflags off width base idx
       = cmmIndexExpr dflags width (cmmOffsetB dflags base off) idx

    cmmLoadIndexOffExpr :: DynFlags
                        -> ByteOff  -- Initial offset in bytes
                        -> CmmType  -- Type of element we are accessing
                        -> CmmExpr  -- Base address
                        -> CmmType  -- Type of element by which we are indexing
                        -> CmmExpr  -- Index
                        -> CmmExpr
    cmmLoadIndexOffExpr dflags off ty base idx_ty idx
       = CmmLoad (cmmIndexOffExpr dflags off (typeWidth idx_ty) base idx) ty

    setInfo :: CmmExpr -> CmmExpr -> CmmAGraph
    setInfo closure_ptr info_ptr = mkStore closure_ptr info_ptr

    ------------------------------------------------------------------------------
    -- Helpers for translating vector primops.

    vecVmmType :: PrimOpVecCat -> Length -> Width -> CmmType
    vecVmmType pocat n w = vec n (vecCmmCat pocat w)

    vecCmmCat :: PrimOpVecCat -> Width -> CmmType
    vecCmmCat IntVec   = cmmBits
    vecCmmCat WordVec  = cmmBits
    vecCmmCat FloatVec = cmmFloat

    vecElemInjectCast :: DynFlags -> PrimOpVecCat -> Width -> Maybe MachOp
    vecElemInjectCast _      FloatVec _   =  Nothing
    vecElemInjectCast dflags IntVec   W8  =  Just (mo_WordTo8  dflags)
    vecElemInjectCast dflags IntVec   W16 =  Just (mo_WordTo16 dflags)
    vecElemInjectCast dflags IntVec   W32 =  Just (mo_WordTo32 dflags)
    vecElemInjectCast _      IntVec   W64 =  Nothing
    vecElemInjectCast dflags WordVec  W8  =  Just (mo_WordTo8  dflags)
    vecElemInjectCast dflags WordVec  W16 =  Just (mo_WordTo16 dflags)
    vecElemInjectCast dflags WordVec  W32 =  Just (mo_WordTo32 dflags)
    vecElemInjectCast _      WordVec  W64 =  Nothing
    vecElemInjectCast _      _        _   =  Nothing

    vecElemProjectCast :: DynFlags -> PrimOpVecCat -> Width -> Maybe MachOp
    vecElemProjectCast _      FloatVec _   =  Nothing
    vecElemProjectCast dflags IntVec   W8  =  Just (mo_s_8ToWord  dflags)
    vecElemProjectCast dflags IntVec   W16 =  Just (mo_s_16ToWord dflags)
    vecElemProjectCast dflags IntVec   W32 =  Just (mo_s_32ToWord dflags)
    vecElemProjectCast _      IntVec   W64 =  Nothing
    vecElemProjectCast dflags WordVec  W8  =  Just (mo_u_8ToWord  dflags)
    vecElemProjectCast dflags WordVec  W16 =  Just (mo_u_16ToWord dflags)
    vecElemProjectCast dflags WordVec  W32 =  Just (mo_u_32ToWord dflags)
    vecElemProjectCast _      WordVec  W64 =  Nothing
    vecElemProjectCast _      _        _   =  Nothing

    -- Check to make sure that we can generate code for the specified vector type
    -- given the current set of dynamic flags.
    checkVecCompatibility :: DynFlags -> PrimOpVecCat -> Length -> Width -> FCode ()
    checkVecCompatibility dflags vcat l w = do
        when (hscTarget dflags /= HscLlvm) $ do
            sorry $ unlines ["SIMD vector instructions require the LLVM back-end."
                             ,"Please use -fllvm."]
        check vecWidth vcat l w
      where
        check :: Width -> PrimOpVecCat -> Length -> Width -> FCode ()
        check W128 FloatVec 4 W32 | not (isSseEnabled dflags) =
            sorry $ "128-bit wide single-precision floating point " ++
                    "SIMD vector instructions require at least -msse."
        check W128 _ _ _ | not (isSse2Enabled dflags) =
            sorry $ "128-bit wide integer and double precision " ++
                    "SIMD vector instructions require at least -msse2."
        check W256 FloatVec _ _ | not (isAvxEnabled dflags) =
            sorry $ "256-bit wide floating point " ++
                    "SIMD vector instructions require at least -mavx."
        check W256 _ _ _ | not (isAvx2Enabled dflags) =
            sorry $ "256-bit wide integer " ++
                    "SIMD vector instructions require at least -mavx2."
        check W512 _ _ _ | not (isAvx512fEnabled dflags) =
            sorry $ "512-bit wide " ++
                    "SIMD vector instructions require -mavx512f."
        check _ _ _ _ = return ()

        vecWidth = typeWidth (vecVmmType vcat l w)

    ------------------------------------------------------------------------------
    -- Helpers for translating vector packing and unpacking.

    doVecPackOp :: Maybe MachOp  -- Cast from element to vector component
                -> CmmType       -- Type of vector
                -> CmmExpr       -- Initial vector
                -> [CmmExpr]     -- Elements
                -> CmmFormal     -- Destination for result
                -> FCode ()
    doVecPackOp maybe_pre_write_cast ty z es res = do
        dst <- newTemp ty
        emitAssign (CmmLocal dst) z
        vecPack dst es 0
      where
        vecPack :: CmmFormal -> [CmmExpr] -> Int -> FCode ()
        vecPack src [] _ =
            emitAssign (CmmLocal res) (CmmReg (CmmLocal src))

        vecPack src (e : es) i = do
            dst <- newTemp ty
            if isFloatType (vecElemType ty)
              then emitAssign (CmmLocal dst) (CmmMachOp (MO_VF_Insert len wid)
                                                        [CmmReg (CmmLocal src), cast e, iLit])
              else emitAssign (CmmLocal dst) (CmmMachOp (MO_V_Insert len wid)
                                                        [CmmReg (CmmLocal src), cast e, iLit])
            vecPack dst es (i + 1)
          where
            -- vector indices are always 32-bits
            iLit = CmmLit (CmmInt (toInteger i) W32)

        cast :: CmmExpr -> CmmExpr
        cast val = case maybe_pre_write_cast of
                     Nothing   -> val
                     Just cast -> CmmMachOp cast [val]

        len :: Length
        len = vecLength ty

        wid :: Width
        wid = typeWidth (vecElemType ty)

    doVecUnpackOp :: Maybe MachOp  -- Cast from vector component to element result
                  -> CmmType       -- Type of vector
                  -> CmmExpr       -- Vector
                  -> [CmmFormal]   -- Element results
                  -> FCode ()
    doVecUnpackOp maybe_post_read_cast ty e res =
        vecUnpack res 0
      where
        vecUnpack :: [CmmFormal] -> Int -> FCode ()
        vecUnpack [] _ =
            return ()

        vecUnpack (r : rs) i = do
            if isFloatType (vecElemType ty)
              then emitAssign (CmmLocal r) (cast (CmmMachOp (MO_VF_Extract len wid)
                                                 [e, iLit]))
              else emitAssign (CmmLocal r) (cast (CmmMachOp (MO_V_Extract len wid)
                                                 [e, iLit]))
            vecUnpack rs (i + 1)
          where
            -- vector indices are always 32-bits
            iLit = CmmLit (CmmInt (toInteger i) W32)

        cast :: CmmExpr -> CmmExpr
        cast val = case maybe_post_read_cast of
                     Nothing   -> val
                     Just cast -> CmmMachOp cast [val]

        len :: Length
        len = vecLength ty

        wid :: Width
        wid = typeWidth (vecElemType ty)

    doVecInsertOp :: Maybe MachOp  -- Cast from element to vector component
                  -> CmmType       -- Vector type
                  -> CmmExpr       -- Source vector
                  -> CmmExpr       -- Element
                  -> CmmExpr       -- Index at which to insert element
                  -> CmmFormal     -- Destination for result
                  -> FCode ()
    doVecInsertOp maybe_pre_write_cast ty src e idx res = do
        dflags <- getDynFlags
        -- vector indices are always 32-bits
        let idx' :: CmmExpr
            idx' = CmmMachOp (MO_SS_Conv (wordWidth dflags) W32) [idx]
        if isFloatType (vecElemType ty)
          then emitAssign (CmmLocal res) (CmmMachOp (MO_VF_Insert len wid) [src, cast e, idx'])
          else emitAssign (CmmLocal res) (CmmMachOp (MO_V_Insert len wid) [src, cast e, idx'])
      where
        cast :: CmmExpr -> CmmExpr
        cast val = case maybe_pre_write_cast of
                     Nothing   -> val
                     Just cast -> CmmMachOp cast [val]

        len :: Length
        len = vecLength ty

        wid :: Width
        wid = typeWidth (vecElemType ty)

    ------------------------------------------------------------------------------
    -- Helpers for translating prefetching.

    -- | Translate byte array prefetch operations into proper primcalls.
    doPrefetchByteArrayOp :: Int
                          -> [CmmExpr]
                          -> FCode ()
    doPrefetchByteArrayOp locality  [addr,idx]
       = do dflags <- getDynFlags
            mkBasicPrefetch locality (arrWordsHdrSize dflags)  addr idx
    doPrefetchByteArrayOp _ _
       = panic "StgCmmPrim: doPrefetchByteArrayOp"

    -- | Translate mutable byte array prefetch operations into proper primcalls.
    doPrefetchMutableByteArrayOp :: Int
                          -> [CmmExpr]
                          -> FCode ()
    doPrefetchMutableByteArrayOp locality  [addr,idx]
       = do dflags <- getDynFlags
            mkBasicPrefetch locality (arrWordsHdrSize dflags)  addr idx
    doPrefetchMutableByteArrayOp _ _
       = panic "StgCmmPrim: doPrefetchByteArrayOp"

    -- | Translate address prefetch operations into proper primcalls.
    doPrefetchAddrOp ::Int
                     -> [CmmExpr]
                     -> FCode ()
    doPrefetchAddrOp locality   [addr,idx]
       = mkBasicPrefetch locality 0  addr idx
    doPrefetchAddrOp _ _
       = panic "StgCmmPrim: doPrefetchAddrOp"

    -- | Translate value prefetch operations into proper primcalls.
    doPrefetchValueOp :: Int
                     -> [CmmExpr]
                     -> FCode ()
    doPrefetchValueOp  locality   [addr]
      =  do dflags <- getDynFlags
            mkBasicPrefetch locality 0 addr  (CmmLit (CmmInt 0 (wordWidth dflags)))
    doPrefetchValueOp _ _
      = panic "StgCmmPrim: doPrefetchValueOp"

    -- | helper to generate prefetch primcalls
    mkBasicPrefetch :: Int          -- Locality level 0-3
                    -> ByteOff      -- Initial offset in bytes
                    -> CmmExpr      -- Base address
                    -> CmmExpr      -- Index
                    -> FCode ()
    mkBasicPrefetch locality off base idx
       = do dflags <- getDynFlags
            emitPrimCall [] (MO_Prefetch_Data locality) [cmmIndexExpr dflags W8 (cmmOffsetB dflags base off) idx]
            return ()

    -- ----------------------------------------------------------------------------
    -- Allocating byte arrays

    -- | Takes a register to return the newly allocated array in and the
    -- size of the new array in bytes. Allocates a new
    -- 'MutableByteArray#'.
    doNewByteArrayOp :: CmmFormal -> ByteOff -> FCode ()
    doNewByteArrayOp res_r n = do
        dflags <- getDynFlags

        let info_ptr = mkLblExpr mkArrWords_infoLabel
            rep = arrWordsRep dflags n

        tickyAllocPrim (mkIntExpr dflags (arrWordsHdrSize dflags))
            (mkIntExpr dflags (nonHdrSize dflags rep))
            (zeroExpr dflags)

        let hdr_size = fixedHdrSize dflags

        base <- allocHeapClosure rep info_ptr curCCS
                         [ (mkIntExpr dflags n,
                            hdr_size + oFFSET_StgArrBytes_bytes dflags)
                         ]

        emit $ mkAssign (CmmLocal res_r) base

    -- ----------------------------------------------------------------------------
    -- Copying byte arrays

    -- | Takes a source 'ByteArray#', an offset in the source array, a
    -- destination 'MutableByteArray#', an offset into the destination
    -- array, and the number of bytes to copy.  Copies the given number of
    -- bytes from the source array to the destination array.
    doCopyByteArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr
                      -> FCode ()
    doCopyByteArrayOp = emitCopyByteArray copy
      where
        -- Copy data (we assume the arrays aren't overlapping since
        -- they're of different types)
        copy _src _dst dst_p src_p bytes =
            emitMemcpyCall dst_p src_p bytes 1

    -- | Takes a source 'MutableByteArray#', an offset in the source
    -- array, a destination 'MutableByteArray#', an offset into the
    -- destination array, and the number of bytes to copy.  Copies the
    -- given number of bytes from the source array to the destination
    -- array.
    doCopyMutableByteArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr
                             -> FCode ()
    doCopyMutableByteArrayOp = emitCopyByteArray copy
      where
        -- The only time the memory might overlap is when the two arrays
        -- we were provided are the same array!
        -- TODO: Optimize branch for common case of no aliasing.
        copy src dst dst_p src_p bytes = do
            dflags <- getDynFlags
            [moveCall, cpyCall] <- forkAlts [
                getCode $ emitMemmoveCall dst_p src_p bytes 1,
                getCode $ emitMemcpyCall  dst_p src_p bytes 1
                ]
            emit =<< mkCmmIfThenElse (cmmEqWord dflags src dst) moveCall cpyCall

    emitCopyByteArray :: (CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr
                          -> FCode ())
                      -> CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr
                      -> FCode ()
    emitCopyByteArray copy src src_off dst dst_off n = do
        dflags <- getDynFlags
        dst_p <- assignTempE $ cmmOffsetExpr dflags (cmmOffsetB dflags dst (arrWordsHdrSize dflags)) dst_off
        src_p <- assignTempE $ cmmOffsetExpr dflags (cmmOffsetB dflags src (arrWordsHdrSize dflags)) src_off
        copy src dst dst_p src_p n

    -- | Takes a source 'ByteArray#', an offset in the source array, a
    -- destination 'Addr#', and the number of bytes to copy.  Copies the given
    -- number of bytes from the source array to the destination memory region.
    doCopyByteArrayToAddrOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> FCode ()
    doCopyByteArrayToAddrOp src src_off dst_p bytes = do
        -- Use memcpy (we are allowed to assume the arrays aren't overlapping)
        dflags <- getDynFlags
        src_p <- assignTempE $ cmmOffsetExpr dflags (cmmOffsetB dflags src (arrWordsHdrSize dflags)) src_off
        emitMemcpyCall dst_p src_p bytes 1

    -- | Takes a source 'MutableByteArray#', an offset in the source array, a
    -- destination 'Addr#', and the number of bytes to copy.  Copies the given
    -- number of bytes from the source array to the destination memory region.
    doCopyMutableByteArrayToAddrOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr
                                   -> FCode ()
    doCopyMutableByteArrayToAddrOp = doCopyByteArrayToAddrOp

    -- | Takes a source 'Addr#', a destination 'MutableByteArray#', an offset into
    -- the destination array, and the number of bytes to copy.  Copies the given
    -- number of bytes from the source memory region to the destination array.
    doCopyAddrToByteArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> FCode ()
    doCopyAddrToByteArrayOp src_p dst dst_off bytes = do
        -- Use memcpy (we are allowed to assume the arrays aren't overlapping)
        dflags <- getDynFlags
        dst_p <- assignTempE $ cmmOffsetExpr dflags (cmmOffsetB dflags dst (arrWordsHdrSize dflags)) dst_off
        emitMemcpyCall dst_p src_p bytes 1

    -- ----------------------------------------------------------------------------
    -- Setting byte arrays

    -- | Takes a 'MutableByteArray#', an offset into the array, a length,
    -- and a byte, and sets each of the selected bytes in the array to the
    -- character.
    doSetByteArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr
                     -> FCode ()
    doSetByteArrayOp ba off len c
        = do dflags <- getDynFlags
             p <- assignTempE $ cmmOffsetExpr dflags (cmmOffsetB dflags ba (arrWordsHdrSize dflags)) off
             emitMemsetCall p c len 1

    -- ----------------------------------------------------------------------------
    -- Allocating arrays

    -- | Allocate a new array.
    doNewArrayOp :: CmmFormal             -- ^ return register
                 -> SMRep                 -- ^ representation of the array
                 -> CLabel                -- ^ info pointer
                 -> [(CmmExpr, ByteOff)]  -- ^ header payload
                 -> WordOff               -- ^ array size
                 -> CmmExpr               -- ^ initial element
                 -> FCode ()
    doNewArrayOp res_r rep info payload n init = do
        dflags <- getDynFlags

        let info_ptr = mkLblExpr info

        tickyAllocPrim (mkIntExpr dflags (hdrSize dflags rep))
            (mkIntExpr dflags (nonHdrSize dflags rep))
            (zeroExpr dflags)

        base <- allocHeapClosure rep info_ptr curCCS payload

        arr <- CmmLocal `fmap` newTemp (bWord dflags)
        emit $ mkAssign arr base

        -- Initialise all elements of the the array
        p <- assignTemp $ cmmOffsetB dflags (CmmReg arr) (hdrSize dflags rep)
        for <- newBlockId
        emitLabel for
        let loopBody =
                [ mkStore (CmmReg (CmmLocal p)) init
                , mkAssign (CmmLocal p) (cmmOffsetW dflags (CmmReg (CmmLocal p)) 1)
                , mkBranch for ]
        emit =<< mkCmmIfThen
            (cmmULtWord dflags (CmmReg (CmmLocal p))
             (cmmOffsetW dflags (CmmReg arr)
              (hdrSizeW dflags rep + n)))
            (catAGraphs loopBody)

        emit $ mkAssign (CmmLocal res_r) (CmmReg arr)

    -- ----------------------------------------------------------------------------
    -- Copying pointer arrays

    -- EZY: This code has an unusually high amount of assignTemp calls, seen
    -- nowhere else in the code generator.  This is mostly because these
    -- "primitive" ops result in a surprisingly large amount of code.  It
    -- will likely be worthwhile to optimize what is emitted here, so that
    -- our optimization passes don't waste time repeatedly optimizing the
    -- same bits of code.

    -- More closely imitates 'assignTemp' from the old code generator, which
    -- returns a CmmExpr rather than a LocalReg.
    assignTempE :: CmmExpr -> FCode CmmExpr
    assignTempE e = do
        t <- assignTemp e
        return (CmmReg (CmmLocal t))

    -- | Takes a source 'Array#', an offset in the source array, a
    -- destination 'MutableArray#', an offset into the destination array,
    -- and the number of elements to copy.  Copies the given number of
    -- elements from the source array to the destination array.
    doCopyArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> WordOff
                  -> FCode ()
    doCopyArrayOp = emitCopyArray copy
      where
        -- Copy data (we assume the arrays aren't overlapping since
        -- they're of different types)
        copy _src _dst dst_p src_p bytes =
            do dflags <- getDynFlags
               emitMemcpyCall dst_p src_p (mkIntExpr dflags bytes)
                   (wORD_SIZE dflags)

    -- | Takes a source 'MutableArray#', an offset in the source array, a
    -- destination 'MutableArray#', an offset into the destination array,
    -- and the number of elements to copy.  Copies the given number of
    -- elements from the source array to the destination array.
    doCopyMutableArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> WordOff
                         -> FCode ()
    doCopyMutableArrayOp = emitCopyArray copy
      where
        -- The only time the memory might overlap is when the two arrays
        -- we were provided are the same array!
        -- TODO: Optimize branch for common case of no aliasing.
        copy src dst dst_p src_p bytes = do
            dflags <- getDynFlags
            [moveCall, cpyCall] <- forkAlts [
                getCode $ emitMemmoveCall dst_p src_p (mkIntExpr dflags bytes)
                (wORD_SIZE dflags),
                getCode $ emitMemcpyCall  dst_p src_p (mkIntExpr dflags bytes)
                (wORD_SIZE dflags)
                ]
            emit =<< mkCmmIfThenElse (cmmEqWord dflags src dst) moveCall cpyCall

    emitCopyArray :: (CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> ByteOff
                      -> FCode ())  -- ^ copy function
                  -> CmmExpr        -- ^ source array
                  -> CmmExpr        -- ^ offset in source array
                  -> CmmExpr        -- ^ destination array
                  -> CmmExpr        -- ^ offset in destination array
                  -> WordOff        -- ^ number of elements to copy
                  -> FCode ()
    emitCopyArray copy src0 src_off dst0 dst_off0 n = do
        dflags <- getDynFlags
        when (n /= 0) $ do
            -- Passed as arguments (be careful)
            src     <- assignTempE src0
            dst     <- assignTempE dst0
            dst_off <- assignTempE dst_off0

            -- Set the dirty bit in the header.
            emit (setInfo dst (CmmLit (CmmLabel mkMAP_DIRTY_infoLabel)))

            dst_elems_p <- assignTempE $ cmmOffsetB dflags dst
                           (arrPtrsHdrSize dflags)
            dst_p <- assignTempE $ cmmOffsetExprW dflags dst_elems_p dst_off
            src_p <- assignTempE $ cmmOffsetExprW dflags
                     (cmmOffsetB dflags src (arrPtrsHdrSize dflags)) src_off
            let bytes = wordsToBytes dflags n

            copy src dst dst_p src_p bytes

            -- The base address of the destination card table
            dst_cards_p <- assignTempE $ cmmOffsetExprW dflags dst_elems_p
                           (loadArrPtrsSize dflags dst)

            emitSetCards dst_off dst_cards_p n

    doCopySmallArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> WordOff
                       -> FCode ()
    doCopySmallArrayOp = emitCopySmallArray copy
      where
        -- Copy data (we assume the arrays aren't overlapping since
        -- they're of different types)
        copy _src _dst dst_p src_p bytes =
            do dflags <- getDynFlags
               emitMemcpyCall dst_p src_p (mkIntExpr dflags bytes)
                   (wORD_SIZE dflags)

    doCopySmallMutableArrayOp :: CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> WordOff
                              -> FCode ()
    doCopySmallMutableArrayOp = emitCopySmallArray copy
      where
        -- The only time the memory might overlap is when the two arrays
        -- we were provided are the same array!
        -- TODO: Optimize branch for common case of no aliasing.
        copy src dst dst_p src_p bytes = do
            dflags <- getDynFlags
            [moveCall, cpyCall] <- forkAlts
                [ getCode $ emitMemmoveCall dst_p src_p (mkIntExpr dflags bytes)
                  (wORD_SIZE dflags)
                , getCode $ emitMemcpyCall  dst_p src_p (mkIntExpr dflags bytes)
                  (wORD_SIZE dflags)
                ]
            emit =<< mkCmmIfThenElse (cmmEqWord dflags src dst) moveCall cpyCall

    emitCopySmallArray :: (CmmExpr -> CmmExpr -> CmmExpr -> CmmExpr -> ByteOff
                           -> FCode ())  -- ^ copy function
                       -> CmmExpr        -- ^ source array
                       -> CmmExpr        -- ^ offset in source array
                       -> CmmExpr        -- ^ destination array
                       -> CmmExpr        -- ^ offset in destination array
                       -> WordOff        -- ^ number of elements to copy
                       -> FCode ()
    emitCopySmallArray copy src0 src_off dst0 dst_off n = do
        dflags <- getDynFlags

        -- Passed as arguments (be careful)
        src     <- assignTempE src0
        dst     <- assignTempE dst0

        -- Set the dirty bit in the header.
        emit (setInfo dst (CmmLit (CmmLabel mkSMAP_DIRTY_infoLabel)))

        dst_p <- assignTempE $ cmmOffsetExprW dflags
                 (cmmOffsetB dflags dst (smallArrPtrsHdrSize dflags)) dst_off
        src_p <- assignTempE $ cmmOffsetExprW dflags
                 (cmmOffsetB dflags src (smallArrPtrsHdrSize dflags)) src_off
        let bytes = wordsToBytes dflags n

        copy src dst dst_p src_p bytes

    -- | Takes an info table label, a register to return the newly
    -- allocated array in, a source array, an offset in the source array,
    -- and the number of elements to copy. Allocates a new array and
    -- initializes it from the source array.
    emitCloneArray :: CLabel -> CmmFormal -> CmmExpr -> CmmExpr -> WordOff
                   -> FCode ()
    emitCloneArray info_p res_r src src_off n = do
        dflags <- getDynFlags

        let info_ptr = mkLblExpr info_p
            rep = arrPtrsRep dflags n

        tickyAllocPrim (mkIntExpr dflags (arrPtrsHdrSize dflags))
            (mkIntExpr dflags (nonHdrSize dflags rep))
            (zeroExpr dflags)

        let hdr_size = fixedHdrSize dflags

        base <- allocHeapClosure rep info_ptr curCCS
                         [ (mkIntExpr dflags n,
                            hdr_size + oFFSET_StgMutArrPtrs_ptrs dflags)
                         , (mkIntExpr dflags (nonHdrSizeW rep),
                            hdr_size + oFFSET_StgMutArrPtrs_size dflags)
                         ]

        arr <- CmmLocal `fmap` newTemp (bWord dflags)
        emit $ mkAssign arr base

        dst_p <- assignTempE $ cmmOffsetB dflags (CmmReg arr)
                 (arrPtrsHdrSize dflags)
        src_p <- assignTempE $ cmmOffsetExprW dflags src
                 (cmmAddWord dflags
                  (mkIntExpr dflags (arrPtrsHdrSizeW dflags)) src_off)

        emitMemcpyCall dst_p src_p (mkIntExpr dflags (wordsToBytes dflags n))
            (wORD_SIZE dflags)

        emit $ mkAssign (CmmLocal res_r) (CmmReg arr)

    -- | Takes an info table label, a register to return the newly
    -- allocated array in, a source array, an offset in the source array,
    -- and the number of elements to copy. Allocates a new array and
    -- initializes it from the source array.
    emitCloneSmallArray :: CLabel -> CmmFormal -> CmmExpr -> CmmExpr -> WordOff
                        -> FCode ()
    emitCloneSmallArray info_p res_r src src_off n = do
        dflags <- getDynFlags

        let info_ptr = mkLblExpr info_p
            rep = smallArrPtrsRep n

        tickyAllocPrim (mkIntExpr dflags (smallArrPtrsHdrSize dflags))
            (mkIntExpr dflags (nonHdrSize dflags rep))
            (zeroExpr dflags)

        let hdr_size = fixedHdrSize dflags

        base <- allocHeapClosure rep info_ptr curCCS
                         [ (mkIntExpr dflags n,
                            hdr_size + oFFSET_StgSmallMutArrPtrs_ptrs dflags)
                         ]

        arr <- CmmLocal `fmap` newTemp (bWord dflags)
        emit $ mkAssign arr base

        dst_p <- assignTempE $ cmmOffsetB dflags (CmmReg arr)
                 (smallArrPtrsHdrSize dflags)
        src_p <- assignTempE $ cmmOffsetExprW dflags src
                 (cmmAddWord dflags
                  (mkIntExpr dflags (smallArrPtrsHdrSizeW dflags)) src_off)

        emitMemcpyCall dst_p src_p (mkIntExpr dflags (wordsToBytes dflags n))
            (wORD_SIZE dflags)

        emit $ mkAssign (CmmLocal res_r) (CmmReg arr)

    -- | Takes and offset in the destination array, the base address of
    -- the card table, and the number of elements affected (*not* the
    -- number of cards). The number of elements may not be zero.
    -- Marks the relevant cards as dirty.
    emitSetCards :: CmmExpr -> CmmExpr -> WordOff -> FCode ()
    emitSetCards dst_start dst_cards_start n = do
        dflags <- getDynFlags
        start_card <- assignTempE $ cardCmm dflags dst_start
        let end_card = cardCmm dflags
                       (cmmSubWord dflags
                        (cmmAddWord dflags dst_start (mkIntExpr dflags n))
                        (mkIntExpr dflags 1))
        emitMemsetCall (cmmAddWord dflags dst_cards_start start_card)
            (mkIntExpr dflags 1)
            (cmmAddWord dflags (cmmSubWord dflags end_card start_card) (mkIntExpr dflags 1))
            1 -- no alignment (1 byte)

    -- Convert an element index to a card index
    cardCmm :: DynFlags -> CmmExpr -> CmmExpr
    cardCmm dflags i =
        cmmUShrWord dflags i (mkIntExpr dflags (mUT_ARR_PTRS_CARD_BITS dflags))

    ------------------------------------------------------------------------------
    -- SmallArray PrimOp implementations

    doReadSmallPtrArrayOp :: LocalReg
                          -> CmmExpr
                          -> CmmExpr
                          -> FCode ()
    doReadSmallPtrArrayOp res addr idx = do
        dflags <- getDynFlags
        mkBasicIndexedRead (smallArrPtrsHdrSize dflags) Nothing (gcWord dflags) res addr
            (gcWord dflags) idx

    doWriteSmallPtrArrayOp :: CmmExpr
                           -> CmmExpr
                           -> CmmExpr
                           -> FCode ()
    doWriteSmallPtrArrayOp addr idx val = do
        dflags <- getDynFlags
        let ty = cmmExprType dflags val
        mkBasicIndexedWrite (smallArrPtrsHdrSize dflags) Nothing addr ty idx val
        emit (setInfo addr (CmmLit (CmmLabel mkSMAP_DIRTY_infoLabel)))

    ------------------------------------------------------------------------------
    -- Atomic read-modify-write

    -- | Emit an atomic modification to a byte array element. The result
    -- reg contains that previous value of the element. Implies a full
    -- memory barrier.
    doAtomicRMW :: LocalReg      -- ^ Result reg
                -> AtomicMachOp  -- ^ Atomic op (e.g. add)
                -> CmmExpr       -- ^ MutableByteArray#
                -> CmmExpr       -- ^ Index
                -> CmmType       -- ^ Type of element by which we are indexing
                -> CmmExpr       -- ^ Op argument (e.g. amount to add)
                -> FCode ()
    doAtomicRMW res amop mba idx idx_ty n = do
        dflags <- getDynFlags
        let width = typeWidth idx_ty
            addr  = cmmIndexOffExpr dflags (arrWordsHdrSize dflags)
                    width mba idx
        emitPrimCall
            [ res ]
            (MO_AtomicRMW width amop)
            [ addr, n ]

    -- | Emit an atomic read to a byte array that acts as a memory barrier.
    doAtomicReadByteArray
        :: LocalReg  -- ^ Result reg
        -> CmmExpr   -- ^ MutableByteArray#
        -> CmmExpr   -- ^ Index
        -> CmmType   -- ^ Type of element by which we are indexing
        -> FCode ()
    doAtomicReadByteArray res mba idx idx_ty = do
        dflags <- getDynFlags
        let width = typeWidth idx_ty
            addr  = cmmIndexOffExpr dflags (arrWordsHdrSize dflags)
                    width mba idx
        emitPrimCall
            [ res ]
            (MO_AtomicRead width)
            [ addr ]

    -- | Emit an atomic write to a byte array that acts as a memory barrier.
    doAtomicWriteByteArray
        :: CmmExpr   -- ^ MutableByteArray#
        -> CmmExpr   -- ^ Index
        -> CmmType   -- ^ Type of element by which we are indexing
        -> CmmExpr   -- ^ Value to write
        -> FCode ()
    doAtomicWriteByteArray mba idx idx_ty val = do
        dflags <- getDynFlags
        let width = typeWidth idx_ty
            addr  = cmmIndexOffExpr dflags (arrWordsHdrSize dflags)
                    width mba idx
        emitPrimCall
            [ {- no results -} ]
            (MO_AtomicWrite width)
            [ addr, val ]

    doCasByteArray
        :: LocalReg  -- ^ Result reg
        -> CmmExpr   -- ^ MutableByteArray#
        -> CmmExpr   -- ^ Index
        -> CmmType   -- ^ Type of element by which we are indexing
        -> CmmExpr   -- ^ Old value
        -> CmmExpr   -- ^ New value
        -> FCode ()
    doCasByteArray res mba idx idx_ty old new = do
        dflags <- getDynFlags
        let width = (typeWidth idx_ty)
            addr = cmmIndexOffExpr dflags (arrWordsHdrSize dflags)
                   width mba idx
        emitPrimCall
            [ res ]
            (MO_Cmpxchg width)
            [ addr, old, new ]

    ------------------------------------------------------------------------------
    -- Helpers for emitting function calls

    -- | Emit a call to @memcpy@.
    emitMemcpyCall :: CmmExpr -> CmmExpr -> CmmExpr -> Int -> FCode ()
    emitMemcpyCall dst src n align = do
        emitPrimCall
            [ {-no results-} ]
            (MO_Memcpy align)
            [ dst, src, n ]

    -- | Emit a call to @memmove@.
    emitMemmoveCall :: CmmExpr -> CmmExpr -> CmmExpr -> Int -> FCode ()
    emitMemmoveCall dst src n align = do
        emitPrimCall
            [ {- no results -} ]
            (MO_Memmove align)
            [ dst, src, n ]

    -- | Emit a call to @memset@.  The second argument must fit inside an
    -- unsigned char.
    emitMemsetCall :: CmmExpr -> CmmExpr -> CmmExpr -> Int -> FCode ()
    emitMemsetCall dst c n align = do
        emitPrimCall
            [ {- no results -} ]
            (MO_Memset align)
            [ dst, c, n ]

    emitBSwapCall :: LocalReg -> CmmExpr -> Width -> FCode ()
    emitBSwapCall res x width = do
        emitPrimCall
            [ res ]
            (MO_BSwap width)
            [ x ]

    emitPopCntCall :: LocalReg -> CmmExpr -> Width -> FCode ()
    emitPopCntCall res x width = do
        emitPrimCall
            [ res ]
            (MO_PopCnt width)
            [ x ]

    emitClzCall :: LocalReg -> CmmExpr -> Width -> FCode ()
    emitClzCall res x width = do
        emitPrimCall
            [ res ]
            (MO_Clz width)
            [ x ]

    emitCtzCall :: LocalReg -> CmmExpr -> Width -> FCode ()
    emitCtzCall res x width = do
        emitPrimCall
            [ res ]
            (MO_Ctz width)
            [ x ]