{-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE LambdaCase #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE ConstraintKinds #-} module Futhark.CodeGen.ImpGen.Kernels ( compileProg ) where import Control.Arrow ((&&&)) import Control.Monad.Except import Control.Monad.Reader import Data.Maybe import Data.Semigroup ((<>)) import qualified Data.Map.Strict as M import qualified Data.Set as S import Data.List import Prelude hiding (quot) import Futhark.Error import Futhark.MonadFreshNames import Futhark.Transform.Rename import Futhark.Representation.ExplicitMemory import qualified Futhark.CodeGen.ImpCode.Kernels as Imp import Futhark.CodeGen.ImpCode.Kernels (bytes) import qualified Futhark.CodeGen.ImpGen as ImpGen import Futhark.CodeGen.ImpGen ((<--), sFor, sWhile, sComment, sIf, sWhen, sUnless, sOp, dPrim, dPrim_, dPrimV) import Futhark.CodeGen.ImpGen.Kernels.Transpose import qualified Futhark.Representation.ExplicitMemory.IndexFunction as IxFun import Futhark.CodeGen.SetDefaultSpace import Futhark.Tools (partitionChunkedKernelLambdaParameters) import Futhark.Util.IntegralExp (quotRoundingUp, quot, rem, IntegralExp) import Futhark.Util (splitAt3) type CallKernelGen = ImpGen.ImpM ExplicitMemory Imp.HostOp type InKernelGen = ImpGen.ImpM InKernel Imp.KernelOp callKernelOperations :: ImpGen.Operations ExplicitMemory Imp.HostOp callKernelOperations = ImpGen.Operations { ImpGen.opsExpCompiler = expCompiler , ImpGen.opsCopyCompiler = callKernelCopy , ImpGen.opsOpCompiler = opCompiler , ImpGen.opsStmsCompiler = ImpGen.defCompileStms } inKernelOperations :: KernelConstants -> ImpGen.Operations InKernel Imp.KernelOp inKernelOperations constants = (ImpGen.defaultOperations $ compileInKernelOp constants) { ImpGen.opsCopyCompiler = inKernelCopy , ImpGen.opsExpCompiler = inKernelExpCompiler , ImpGen.opsStmsCompiler = \_ -> compileKernelStms constants } compileProg :: MonadFreshNames m => Prog ExplicitMemory -> m (Either InternalError Imp.Program) compileProg prog = fmap (setDefaultSpace (Imp.Space "device")) <$> ImpGen.compileProg callKernelOperations (Imp.Space "device") prog opCompiler :: Pattern ExplicitMemory -> Op ExplicitMemory -> CallKernelGen () opCompiler dest (Alloc e space) = ImpGen.compileAlloc dest e space opCompiler dest (Inner kernel) = kernelCompiler dest kernel compileInKernelOp :: KernelConstants -> Pattern InKernel -> Op InKernel -> InKernelGen () compileInKernelOp _ (Pattern _ [mem]) Alloc{} = compilerLimitationS $ "Cannot allocate memory block " ++ pretty mem ++ " in kernel." compileInKernelOp _ dest Alloc{} = compilerBugS $ "Invalid target for in-kernel allocation: " ++ show dest compileInKernelOp constants pat (Inner op) = compileKernelExp constants pat op -- | Recognise kernels (maps), give everything else back. kernelCompiler :: Pattern ExplicitMemory -> Kernel InKernel -> CallKernelGen () kernelCompiler (Pattern _ [pe]) (GetSize key size_class) = sOp $ Imp.GetSize (patElemName pe) key size_class kernelCompiler (Pattern _ [pe]) (CmpSizeLe key size_class x) = sOp . Imp.CmpSizeLe (patElemName pe) key size_class =<< ImpGen.compileSubExp x kernelCompiler (Pattern _ [pe]) (GetSizeMax size_class) = sOp $ Imp.GetSizeMax (patElemName pe) size_class kernelCompiler pat (Kernel desc space _ kernel_body) = do group_size' <- ImpGen.subExpToDimSize $ spaceGroupSize space num_threads' <- ImpGen.subExpToDimSize $ spaceNumThreads space let bound_in_kernel = M.keys $ scopeOfKernelSpace space <> scopeOf (kernelBodyStms kernel_body) let global_tid = spaceGlobalId space local_tid = spaceLocalId space group_id = spaceGroupId space wave_size <- newVName "wave_size" inner_group_size <- newVName "group_size" thread_active <- newVName "thread_active" let (space_is, space_dims) = unzip $ spaceDimensions space space_dims' <- mapM ImpGen.compileSubExp space_dims let constants = KernelConstants global_tid local_tid group_id group_size' num_threads' (Imp.VarSize wave_size) (zip space_is space_dims') (Imp.var thread_active Bool) mempty kernel_body' <- makeAllMemoryGlobal $ ImpGen.subImpM_ (inKernelOperations constants) $ do dPrim_ wave_size int32 dPrim_ inner_group_size int32 dPrim_ thread_active Bool ImpGen.dScope Nothing (scopeOfKernelSpace space) sOp (Imp.GetGlobalId global_tid 0) sOp (Imp.GetLocalId local_tid 0) sOp (Imp.GetLocalSize inner_group_size 0) sOp (Imp.GetLockstepWidth wave_size) sOp (Imp.GetGroupId group_id 0) setSpaceIndices space thread_active <-- isActive (spaceDimensions space) compileKernelBody pat constants kernel_body (uses, local_memory) <- computeKernelUses kernel_body' bound_in_kernel forM_ (kernelHints desc) $ \(s,v) -> do ty <- case v of Constant pv -> return $ Prim $ primValueType pv Var vn -> lookupType vn unless (primType ty) $ fail $ concat [ "debugKernelHint '", s, "'" , " in kernel '", kernelName desc, "'" , " did not have primType value." ] ImpGen.compileSubExp v >>= ImpGen.emit . Imp.DebugPrint s (elemType ty) sOp $ Imp.CallKernel $ Imp.AnyKernel Imp.Kernel { Imp.kernelBody = kernel_body' , Imp.kernelLocalMemory = local_memory , Imp.kernelUses = uses , Imp.kernelNumGroups = [ImpGen.compileSubExpOfType int32 $ spaceNumGroups space] , Imp.kernelGroupSize = [ImpGen.compileSubExpOfType int32 $ spaceGroupSize space] , Imp.kernelName = nameFromString $ kernelName desc ++ "_" ++ show (baseTag global_tid) } kernelCompiler pat e = compilerBugS $ "ImpGen.kernelCompiler: Invalid pattern\n " ++ pretty pat ++ "\nfor expression\n " ++ pretty e expCompiler :: ImpGen.ExpCompiler ExplicitMemory Imp.HostOp -- We generate a simple kernel for itoa and replicate. expCompiler (Pattern _ [pe]) (BasicOp (Iota n x s et)) = do destloc <- ImpGen.entryArrayLocation <$> ImpGen.lookupArray (patElemName pe) let tag = Just $ baseTag $ patElemName pe thread_gid <- maybe (newVName "thread_gid") (return . VName (nameFromString "thread_gid")) tag makeAllMemoryGlobal $ do (destmem, destspace, destidx) <- ImpGen.fullyIndexArray' destloc [ImpGen.varIndex thread_gid] (IntType et) n' <- ImpGen.compileSubExp n x' <- ImpGen.compileSubExp x s' <- ImpGen.compileSubExp s let body = Imp.Write destmem destidx (IntType et) destspace Imp.Nonvolatile $ Imp.ConvOpExp (SExt Int32 et) (Imp.var thread_gid int32) * s' + x' (group_size, num_groups) <- computeMapKernelGroups n' (body_uses, _) <- computeKernelUses (freeIn body <> freeIn [n',x',s']) [thread_gid] sOp $ Imp.CallKernel $ Imp.Map Imp.MapKernel { Imp.mapKernelThreadNum = thread_gid , Imp.mapKernelDesc = "iota" , Imp.mapKernelNumGroups = Imp.VarSize num_groups , Imp.mapKernelGroupSize = Imp.VarSize group_size , Imp.mapKernelSize = n' , Imp.mapKernelUses = body_uses , Imp.mapKernelBody = body } expCompiler (Pattern _ [pe]) (BasicOp (Replicate (Shape ds) se)) = do constants <- simpleKernelConstants (Just $ baseTag $ patElemName pe) "replicate" t <- subExpType se let thread_gid = kernelGlobalThreadId constants row_dims = arrayDims t dims = ds ++ row_dims is' = unflattenIndex (map (ImpGen.compileSubExpOfType int32) dims) $ ImpGen.varIndex thread_gid ds' <- mapM ImpGen.compileSubExp ds makeAllMemoryGlobal $ do body <- ImpGen.subImpM_ (inKernelOperations constants) $ ImpGen.copyDWIM (patElemName pe) is' se $ drop (length ds) is' dims' <- mapM ImpGen.compileSubExp dims (group_size, num_groups) <- computeMapKernelGroups $ product dims' (body_uses, _) <- computeKernelUses (freeIn body <> freeIn ds') [thread_gid] sOp $ Imp.CallKernel $ Imp.Map Imp.MapKernel { Imp.mapKernelThreadNum = thread_gid , Imp.mapKernelDesc = "replicate" , Imp.mapKernelNumGroups = Imp.VarSize num_groups , Imp.mapKernelGroupSize = Imp.VarSize group_size , Imp.mapKernelSize = product dims' , Imp.mapKernelUses = body_uses , Imp.mapKernelBody = body } -- Allocation in the "local" space is just a placeholder. expCompiler _ (Op (Alloc _ (Space "local"))) = return () expCompiler dest e = ImpGen.defCompileExp dest e callKernelCopy :: ImpGen.CopyCompiler ExplicitMemory Imp.HostOp callKernelCopy bt destloc@(ImpGen.MemLocation destmem destshape destIxFun) srcloc@(ImpGen.MemLocation srcmem srcshape srcIxFun) n | Just (destoffset, srcoffset, num_arrays, size_x, size_y, src_elems, dest_elems) <- isMapTransposeKernel bt destloc srcloc = do fname <- mapTransposeForType bt ImpGen.emit $ Imp.Call [] fname [Imp.MemArg destmem, Imp.ExpArg destoffset, Imp.MemArg srcmem, Imp.ExpArg srcoffset, Imp.ExpArg num_arrays, Imp.ExpArg size_x, Imp.ExpArg size_y, Imp.ExpArg src_elems, Imp.ExpArg dest_elems] | bt_size <- primByteSize bt, ixFunMatchesInnerShape (Shape $ map Imp.sizeToExp destshape) destIxFun, ixFunMatchesInnerShape (Shape $ map Imp.sizeToExp srcshape) srcIxFun, Just destoffset <- IxFun.linearWithOffset destIxFun bt_size, Just srcoffset <- IxFun.linearWithOffset srcIxFun bt_size = do let row_size = product $ map ImpGen.dimSizeToExp $ drop 1 srcshape srcspace <- ImpGen.entryMemSpace <$> ImpGen.lookupMemory srcmem destspace <- ImpGen.entryMemSpace <$> ImpGen.lookupMemory destmem ImpGen.emit $ Imp.Copy destmem (bytes destoffset) destspace srcmem (bytes srcoffset) srcspace $ (n * row_size) `Imp.withElemType` bt | otherwise = do global_thread_index <- newVName "copy_global_thread_index" -- Note that the shape of the destination and the source are -- necessarily the same. let shape = map Imp.sizeToExp srcshape shape_se = map (Imp.innerExp . ImpGen.dimSizeToExp) srcshape dest_is = unflattenIndex shape_se $ ImpGen.varIndex global_thread_index src_is = dest_is makeAllMemoryGlobal $ do (_, destspace, destidx) <- ImpGen.fullyIndexArray' destloc dest_is bt (_, srcspace, srcidx) <- ImpGen.fullyIndexArray' srcloc src_is bt let body = Imp.Write destmem destidx bt destspace Imp.Nonvolatile $ Imp.index srcmem srcidx bt srcspace Imp.Nonvolatile let writes_to = [Imp.MemoryUse destmem] reads_from <- readsFromSet $ S.singleton srcmem <> freeIn destIxFun <> freeIn srcIxFun <> freeIn destshape let kernel_size = Imp.innerExp n * product (drop 1 shape) (group_size, num_groups) <- computeMapKernelGroups kernel_size let bound_in_kernel = [global_thread_index] (body_uses, _) <- computeKernelUses (kernel_size, body) bound_in_kernel sOp $ Imp.CallKernel $ Imp.Map Imp.MapKernel { Imp.mapKernelThreadNum = global_thread_index , Imp.mapKernelDesc = "copy" , Imp.mapKernelNumGroups = Imp.VarSize num_groups , Imp.mapKernelGroupSize = Imp.VarSize group_size , Imp.mapKernelSize = kernel_size , Imp.mapKernelUses = nub $ body_uses ++ writes_to ++ reads_from , Imp.mapKernelBody = body } -- | We have no bulk copy operation (e.g. memmove) inside kernels, so -- turn any copy into a loop. inKernelCopy :: ImpGen.CopyCompiler InKernel Imp.KernelOp inKernelCopy = ImpGen.copyElementWise mapTransposeForType :: PrimType -> ImpGen.ImpM ExplicitMemory Imp.HostOp Name mapTransposeForType bt = do -- XXX: The leading underscore is to avoid clashes with a -- programmer-defined function of the same name (this is a bad -- solution...). let fname = nameFromString $ "_" <> mapTransposeName bt exists <- ImpGen.hasFunction fname unless exists $ ImpGen.emitFunction fname $ mapTransposeFunction bt return fname mapTransposeName :: PrimType -> String mapTransposeName bt = "map_transpose_" ++ pretty bt mapTransposeFunction :: PrimType -> Imp.Function mapTransposeFunction bt = Imp.Function False [] params transpose_code [] [] where params = [memparam destmem, intparam destoffset, memparam srcmem, intparam srcoffset, intparam num_arrays, intparam x, intparam y, intparam in_elems, intparam out_elems] space = Space "device" memparam v = Imp.MemParam v space intparam v = Imp.ScalarParam v $ IntType Int32 [destmem, destoffset, srcmem, srcoffset, num_arrays, x, y, in_elems, out_elems, mulx, muly, block] = zipWith (VName . nameFromString) ["destmem", "destoffset", "srcmem", "srcoffset", "num_arrays", "x_elems", "y_elems", "in_elems", "out_elems", -- The following is only used for low width/height -- transpose kernels "mulx", "muly", "block" ] [0..] v32 v = Imp.var v int32 block_dim_int = 16 block_dim :: IntegralExp a => a block_dim = 16 -- When an input array has either width==1 or height==1, performing a -- transpose will be the same as performing a copy. If 'input_size' or -- 'output_size' is not equal to width*height, then this trick will not -- work when there are more than one array to process, as it is a per -- array limit. We could copy each array individually, but currently we -- do not. can_use_copy = let in_out_eq = CmpOpExp (CmpEq $ IntType Int32) (v32 in_elems) (v32 out_elems) onearr = CmpOpExp (CmpEq $ IntType Int32) (v32 num_arrays) 1 noprob_widthheight = CmpOpExp (CmpEq $ IntType Int32) (v32 x * v32 y) (v32 in_elems) height_is_one = CmpOpExp (CmpEq $ IntType Int32) (v32 y) 1 width_is_one = CmpOpExp (CmpEq $ IntType Int32) (v32 x) 1 in BinOpExp LogAnd in_out_eq (BinOpExp LogAnd (BinOpExp LogOr onearr noprob_widthheight) (BinOpExp LogOr width_is_one height_is_one)) transpose_code = Imp.If input_is_empty mempty $ mconcat [ Imp.DeclareScalar muly (IntType Int32) , Imp.SetScalar muly $ block_dim `quot` v32 x , Imp.DeclareScalar mulx (IntType Int32) , Imp.SetScalar mulx $ block_dim `quot` v32 y , Imp.If can_use_copy copy_code $ Imp.If should_use_lowwidth (callTransposeKernel TransposeLowWidth) $ Imp.If should_use_lowheight (callTransposeKernel TransposeLowHeight) $ Imp.If should_use_small (callTransposeKernel TransposeSmall) $ callTransposeKernel TransposeNormal] input_is_empty = v32 num_arrays .==. 0 .||. v32 x .==. 0 .||. v32 y .==. 0 should_use_small = BinOpExp LogAnd (CmpOpExp (CmpSle Int32) (v32 x) (block_dim `quot` 2)) (CmpOpExp (CmpSle Int32) (v32 y) (block_dim `quot` 2)) should_use_lowwidth = BinOpExp LogAnd (CmpOpExp (CmpSle Int32) (v32 x) (block_dim `quot` 2)) (CmpOpExp (CmpSlt Int32) block_dim (v32 y)) should_use_lowheight = BinOpExp LogAnd (CmpOpExp (CmpSle Int32) (v32 y) (block_dim `quot` 2)) (CmpOpExp (CmpSlt Int32) block_dim (v32 x)) copy_code = let num_bytes = v32 in_elems * Imp.LeafExp (Imp.SizeOf bt) (IntType Int32) in Imp.Copy destmem (Imp.Count $ v32 destoffset) space srcmem (Imp.Count $ v32 srcoffset) space (Imp.Count num_bytes) callTransposeKernel = Imp.Op . Imp.CallKernel . Imp.AnyKernel . mapTransposeKernel (mapTransposeName bt) block_dim_int (destmem, v32 destoffset, srcmem, v32 srcoffset, v32 x, v32 y, v32 in_elems, v32 out_elems, v32 mulx, v32 muly, v32 num_arrays, block) bt inKernelExpCompiler :: ImpGen.ExpCompiler InKernel Imp.KernelOp inKernelExpCompiler _ (BasicOp (Assert _ _ (loc, locs))) = compilerLimitationS $ unlines [ "Cannot compile assertion at " ++ intercalate " -> " (reverse $ map locStr $ loc:locs) ++ " inside parallel kernel." , "As a workaround, surround the expression with 'unsafe'."] -- The static arrays stuff does not work inside kernels. inKernelExpCompiler (Pattern _ [dest]) (BasicOp (ArrayLit es _)) = forM_ (zip [0..] es) $ \(i,e) -> ImpGen.copyDWIM (patElemName dest) [fromIntegral (i::Int32)] e [] inKernelExpCompiler dest e = ImpGen.defCompileExp dest e computeKernelUses :: FreeIn a => a -> [VName] -> CallKernelGen ([Imp.KernelUse], [Imp.LocalMemoryUse]) computeKernelUses kernel_body bound_in_kernel = do let actually_free = freeIn kernel_body `S.difference` S.fromList bound_in_kernel -- Compute the variables that we need to pass to the kernel. reads_from <- readsFromSet actually_free -- Are we using any local memory? local_memory <- computeLocalMemoryUse actually_free return (nub reads_from, nub local_memory) readsFromSet :: Names -> CallKernelGen [Imp.KernelUse] readsFromSet free = fmap catMaybes $ forM (S.toList free) $ \var -> do t <- lookupType var case t of Array {} -> return Nothing Mem _ (Space "local") -> return Nothing Mem _ _ -> return $ Just $ Imp.MemoryUse var Prim bt -> isConstExp var >>= \case Just ce -> return $ Just $ Imp.ConstUse var ce Nothing | bt == Cert -> return Nothing | otherwise -> return $ Just $ Imp.ScalarUse var bt computeLocalMemoryUse :: Names -> CallKernelGen [Imp.LocalMemoryUse] computeLocalMemoryUse free = fmap catMaybes $ forM (S.toList free) $ \var -> do t <- lookupType var case t of Mem memsize (Space "local") -> do memsize' <- localMemSize =<< ImpGen.subExpToDimSize memsize return $ Just (var, memsize') _ -> return Nothing localMemSize :: Imp.MemSize -> CallKernelGen (Either Imp.MemSize Imp.KernelConstExp) localMemSize (Imp.ConstSize x) = return $ Right $ ValueExp $ IntValue $ Int64Value x localMemSize (Imp.VarSize v) = isConstExp v >>= \case Just e | isStaticExp e -> return $ Right e _ -> return $ Left $ Imp.VarSize v -- | Only some constant expressions quality as *static* expressions, -- which we can use for static memory allocation. This is a bit of a -- hack, as it is primarly motivated by what you can put as the size -- when daring an array in C. isStaticExp :: Imp.KernelConstExp -> Bool isStaticExp LeafExp{} = True isStaticExp ValueExp{} = True isStaticExp (BinOpExp Add{} x y) = isStaticExp x && isStaticExp y isStaticExp (BinOpExp Sub{} x y) = isStaticExp x && isStaticExp y isStaticExp (BinOpExp Mul{} x y) = isStaticExp x && isStaticExp y isStaticExp _ = False isConstExp :: VName -> CallKernelGen (Maybe Imp.KernelConstExp) isConstExp v = do vtable <- ImpGen.getVTable let lookupConstExp name = constExp =<< hasExp =<< M.lookup name vtable constExp (Op (Inner (GetSize key _))) = Just $ LeafExp (Imp.SizeConst key) int32 constExp e = primExpFromExp lookupConstExp e return $ lookupConstExp v where hasExp (ImpGen.ArrayVar e _) = e hasExp (ImpGen.ScalarVar e _) = e hasExp (ImpGen.MemVar e _) = e -- | Change every memory block to be in the global address space, -- except those who are in the local memory space. This only affects -- generated code - we still need to make sure that the memory is -- actually present on the device (and dared as variables in the -- kernel). makeAllMemoryGlobal :: CallKernelGen a -> CallKernelGen a makeAllMemoryGlobal = local (\env -> env { ImpGen.envDefaultSpace = Imp.Space "global" }) . ImpGen.localVTable (M.map globalMemory) where globalMemory (ImpGen.MemVar _ entry) | ImpGen.entryMemSpace entry /= Space "local" = ImpGen.MemVar Nothing entry { ImpGen.entryMemSpace = Imp.Space "global" } globalMemory entry = entry computeMapKernelGroups :: Imp.Exp -> CallKernelGen (VName, VName) computeMapKernelGroups kernel_size = do group_size <- dPrim "group_size" int32 let group_size_var = Imp.var group_size int32 sOp $ Imp.GetSize group_size group_size Imp.SizeGroup num_groups <- dPrimV "num_groups" $ kernel_size `quotRoundingUp` Imp.ConvOpExp (SExt Int32 Int32) group_size_var return (group_size, num_groups) isMapTransposeKernel :: PrimType -> ImpGen.MemLocation -> ImpGen.MemLocation -> Maybe (Imp.Exp, Imp.Exp, Imp.Exp, Imp.Exp, Imp.Exp, Imp.Exp, Imp.Exp) isMapTransposeKernel bt (ImpGen.MemLocation _ _ destIxFun) (ImpGen.MemLocation _ _ srcIxFun) | Just (dest_offset, perm_and_destshape) <- IxFun.rearrangeWithOffset destIxFun bt_size, (perm, destshape) <- unzip perm_and_destshape, srcshape' <- IxFun.shape srcIxFun, Just src_offset <- IxFun.linearWithOffset srcIxFun bt_size, Just (r1, r2, _) <- isMapTranspose perm = isOk (product srcshape') (product destshape) destshape swap r1 r2 dest_offset src_offset | Just dest_offset <- IxFun.linearWithOffset destIxFun bt_size, Just (src_offset, perm_and_srcshape) <- IxFun.rearrangeWithOffset srcIxFun bt_size, (perm, srcshape) <- unzip perm_and_srcshape, destshape' <- IxFun.shape destIxFun, Just (r1, r2, _) <- isMapTranspose perm = isOk (product srcshape) (product destshape') srcshape id r1 r2 dest_offset src_offset | otherwise = Nothing where bt_size = primByteSize bt swap (x,y) = (y,x) isOk src_elems dest_elems shape f r1 r2 dest_offset src_offset = do let (num_arrays, size_x, size_y) = getSizes shape f r1 r2 return (dest_offset, src_offset, num_arrays, size_x, size_y, src_elems, dest_elems) getSizes shape f r1 r2 = let (mapped, notmapped) = splitAt r1 shape (pretrans, posttrans) = f $ splitAt r2 notmapped in (product mapped, product pretrans, product posttrans) writeParamToLocalMemory :: Typed (MemBound u) => Imp.Exp -> (VName, t) -> Param (MemBound u) -> ImpGen.ImpM lore op () writeParamToLocalMemory i (mem, _) param | Prim t <- paramType param = ImpGen.emit $ Imp.Write mem (bytes i') bt (Space "local") Imp.Volatile $ Imp.var (paramName param) t | otherwise = return () where i' = i * Imp.LeafExp (Imp.SizeOf bt) int32 bt = elemType $ paramType param readParamFromLocalMemory :: Typed (MemBound u) => VName -> Imp.Exp -> Param (MemBound u) -> (VName, t) -> ImpGen.ImpM lore op () readParamFromLocalMemory index i param (l_mem, _) | Prim _ <- paramType param = paramName param <-- Imp.index l_mem (bytes i') bt (Space "local") Imp.Volatile | otherwise = index <-- i where i' = i * Imp.LeafExp (Imp.SizeOf bt) int32 bt = elemType $ paramType param computeThreadChunkSize :: SplitOrdering -> Imp.Exp -> Imp.Count Imp.Elements -> Imp.Count Imp.Elements -> VName -> ImpGen.ImpM lore op () computeThreadChunkSize (SplitStrided stride) thread_index elements_per_thread num_elements chunk_var = do stride' <- ImpGen.compileSubExp stride chunk_var <-- Imp.BinOpExp (SMin Int32) (Imp.innerExp elements_per_thread) ((Imp.innerExp num_elements - thread_index) `quotRoundingUp` stride') computeThreadChunkSize SplitContiguous thread_index elements_per_thread num_elements chunk_var = do starting_point <- dPrimV "starting_point" $ thread_index * Imp.innerExp elements_per_thread remaining_elements <- dPrimV "remaining_elements" $ Imp.innerExp num_elements - Imp.var starting_point int32 let no_remaining_elements = Imp.var remaining_elements int32 .<=. 0 beyond_bounds = Imp.innerExp num_elements .<=. Imp.var starting_point int32 sIf (no_remaining_elements .||. beyond_bounds) (chunk_var <-- 0) (sIf is_last_thread (chunk_var <-- Imp.innerExp last_thread_elements) (chunk_var <-- Imp.innerExp elements_per_thread)) where last_thread_elements = num_elements - Imp.elements thread_index * elements_per_thread is_last_thread = Imp.innerExp num_elements .<. (thread_index + 1) * Imp.innerExp elements_per_thread inBlockScan :: Imp.Exp -> Imp.Exp -> Imp.Exp -> VName -> [(VName, t)] -> Lambda InKernel -> InKernelGen () inBlockScan lockstep_width block_size active local_id acc_local_mem scan_lam = ImpGen.everythingVolatile $ do skip_threads <- dPrim "skip_threads" int32 let in_block_thread_active = Imp.var skip_threads int32 .<=. in_block_id (scan_lam_i, other_index_param, actual_params) = partitionChunkedKernelLambdaParameters $ lambdaParams scan_lam (x_params, y_params) = splitAt (length actual_params `div` 2) actual_params read_operands = zipWithM_ (readParamFromLocalMemory (paramName other_index_param) $ Imp.var local_id int32 - Imp.var skip_threads int32) x_params acc_local_mem -- Set initial y values sWhen active $ zipWithM_ (readParamFromLocalMemory scan_lam_i $ Imp.var local_id int32) y_params acc_local_mem let op_to_y = ImpGen.compileBody' y_params $ lambdaBody scan_lam write_operation_result = zipWithM_ (writeParamToLocalMemory $ Imp.var local_id int32) acc_local_mem y_params maybeBarrier = sWhen (lockstep_width .<=. Imp.var skip_threads int32) $ sOp Imp.Barrier sComment "in-block scan (hopefully no barriers needed)" $ do skip_threads <-- 1 sWhile (Imp.var skip_threads int32 .<. block_size) $ do sWhen (in_block_thread_active .&&. active) $ do sComment "read operands" read_operands sComment "perform operation" op_to_y maybeBarrier sWhen (in_block_thread_active .&&. active) $ sComment "write result" write_operation_result maybeBarrier skip_threads <-- Imp.var skip_threads int32 * 2 where block_id = Imp.var local_id int32 `quot` block_size in_block_id = Imp.var local_id int32 - block_id * block_size data KernelConstants = KernelConstants { kernelGlobalThreadId :: VName , kernelLocalThreadId :: VName , kernelGroupId :: VName , kernelGroupSize :: Imp.DimSize , _kernelNumThreads :: Imp.DimSize , kernelWaveSize :: Imp.DimSize , kernelDimensions :: [(VName, Imp.Exp)] , kernelThreadActive :: Imp.Exp , kernelStreamed :: [(VName, Imp.DimSize)] -- ^ Chunk sizez and their maximum size. Hint -- for unrolling. } -- FIXME: wing a KernelConstants structure for use in Replicate -- compilation. This cannot be the best way to do this... simpleKernelConstants :: MonadFreshNames m => Maybe Int -> String -> m KernelConstants simpleKernelConstants tag desc = do thread_gtid <- maybe (newVName $ desc ++ "_gtid") (return . VName (nameFromString $ desc ++ "_gtid")) tag thread_ltid <- newVName $ desc ++ "_ltid" thread_gid <- newVName $ desc ++ "_gid" return $ KernelConstants thread_gtid thread_ltid thread_gid (Imp.ConstSize 0) (Imp.ConstSize 0) (Imp.ConstSize 0) [] (Imp.ValueExp $ BoolValue True) mempty compileKernelBody :: Pattern InKernel -> KernelConstants -> KernelBody InKernel -> InKernelGen () compileKernelBody pat constants kbody = compileKernelStms constants (stmsToList $ kernelBodyStms kbody) $ zipWithM_ (compileKernelResult constants) (patternElements pat) $ kernelBodyResult kbody compileKernelStms :: KernelConstants -> [Stm InKernel] -> InKernelGen a -> InKernelGen a compileKernelStms constants ungrouped_bnds m = compileGroupedKernelStms' $ groupStmsByGuard constants ungrouped_bnds where compileGroupedKernelStms' [] = m compileGroupedKernelStms' ((g, bnds):rest_bnds) = do ImpGen.dScopes (map ((Just . stmExp) &&& (castScope . scopeOf)) bnds) protect g $ mapM_ compileKernelStm bnds compileGroupedKernelStms' rest_bnds protect Nothing body_m = body_m protect (Just (Imp.ValueExp (BoolValue True))) body_m = body_m protect (Just g) body_m = sWhen g $ allThreads constants body_m compileKernelStm (Let pat _ e) = ImpGen.compileExp pat e groupStmsByGuard :: KernelConstants -> [Stm InKernel] -> [(Maybe Imp.Exp, [Stm InKernel])] groupStmsByGuard constants bnds = map collapse $ groupBy sameGuard $ zip (map bindingGuard bnds) bnds where bindingGuard (Let _ _ Op{}) = Nothing bindingGuard _ = Just $ kernelThreadActive constants sameGuard (g1, _) (g2, _) = g1 == g2 collapse [] = (Nothing, []) collapse l@((g,_):_) = (g, map snd l) compileKernelExp :: KernelConstants -> Pattern InKernel -> KernelExp InKernel -> InKernelGen () compileKernelExp _ pat (Barrier ses) = do forM_ (zip (patternNames pat) ses) $ \(d, se) -> ImpGen.copyDWIM d [] se [] sOp Imp.Barrier compileKernelExp _ (Pattern [] [size]) (SplitSpace o w i elems_per_thread) = do num_elements <- Imp.elements <$> ImpGen.compileSubExp w i' <- ImpGen.compileSubExp i elems_per_thread' <- Imp.elements <$> ImpGen.compileSubExp elems_per_thread computeThreadChunkSize o i' elems_per_thread' num_elements (patElemName size) compileKernelExp constants pat (Combine (CombineSpace scatter cspace) _ aspace body) = do -- First we compute how many times we have to iterate to cover -- cspace with our group size. It is a fairly common case that -- we statically know that this requires 1 iteration, so we -- could detect it and not generate a loop in that case. -- However, it seems to have no impact on performance (an extra -- conditional jump), so for simplicity we just always generate -- the loop. let cspace_dims = map (streamBounded . snd) cspace num_iters | cspace_dims == [Imp.sizeToExp $ kernelGroupSize constants] = 1 | otherwise = product cspace_dims `quotRoundingUp` Imp.sizeToExp (kernelGroupSize constants) iter <- newVName "comb_iter" sFor iter Int32 num_iters $ do mapM_ ((`dPrim_` int32) . fst) cspace -- Compute the *flat* array index. cid <- dPrimV "flat_comb_id" $ Imp.var iter int32 * Imp.sizeToExp (kernelGroupSize constants) + Imp.var (kernelLocalThreadId constants) int32 -- Turn it into a nested array index. zipWithM_ (<--) (map fst cspace) $ unflattenIndex cspace_dims (Imp.var cid int32) -- Construct the body. This is mostly about the book-keeping -- for the scatter-like part. let (scatter_ws, scatter_ns, _scatter_vs) = unzip3 scatter scatter_ws_repl = concat $ zipWith replicate scatter_ns scatter_ws (scatter_pes, normal_pes) = splitAt (sum scatter_ns) $ patternElements pat (res_is, res_vs, res_normal) = splitAt3 (sum scatter_ns) (sum scatter_ns) $ bodyResult body -- Execute the body if we are within bounds. sWhen (isActive cspace .&&. isActive aspace) $ allThreads constants $ ImpGen.compileStms (freeIn $ bodyResult body) (stmsToList $ bodyStms body) $ do forM_ (zip4 scatter_ws_repl res_is res_vs scatter_pes) $ \(w, res_i, res_v, scatter_pe) -> do let res_i' = ImpGen.compileSubExpOfType int32 res_i w' = ImpGen.compileSubExpOfType int32 w -- We have to check that 'res_i' is in-bounds wrt. an array of size 'w'. in_bounds = 0 .<=. res_i' .&&. res_i' .<. w' sWhen in_bounds $ ImpGen.copyDWIM (patElemName scatter_pe) [res_i'] res_v [] forM_ (zip normal_pes res_normal) $ \(pe, res) -> ImpGen.copyDWIM (patElemName pe) local_index res [] sOp Imp.Barrier where streamBounded (Var v) | Just x <- lookup v $ kernelStreamed constants = Imp.sizeToExp x streamBounded se = ImpGen.compileSubExpOfType int32 se local_index = map (ImpGen.compileSubExpOfType int32 . Var . fst) cspace compileKernelExp constants (Pattern _ dests) (GroupReduce w lam input) = do groupReduce constants w lam $ map snd input let (reduce_acc_params, _) = splitAt (length input) $ drop 2 $ lambdaParams lam forM_ (zip dests reduce_acc_params) $ \(dest, reduce_acc_param) -> ImpGen.copyDWIM (patElemName dest) [] (Var $ paramName reduce_acc_param) [] compileKernelExp constants _ (GroupScan w lam input) = do renamed_lam <- renameLambda lam w' <- ImpGen.compileSubExp w when (any (not . primType . paramType) $ lambdaParams lam) $ compilerLimitationS "Cannot compile parallel scans with array element type." let local_tid = kernelLocalThreadId constants (_nes, arrs) = unzip input (lam_i, other_index_param, actual_params) = partitionChunkedKernelLambdaParameters $ lambdaParams lam (x_params, y_params) = splitAt (length input) actual_params ImpGen.dLParams (lambdaParams lam++lambdaParams renamed_lam) lam_i <-- Imp.var local_tid int32 acc_local_mem <- flip zip (repeat ()) <$> mapM (fmap (ImpGen.memLocationName . ImpGen.entryArrayLocation) . ImpGen.lookupArray) arrs -- The scan works by splitting the group into blocks, which are -- scanned separately. Typically, these blocks are smaller than -- the lockstep width, which enables barrier-free execution inside -- them. -- -- We hardcode the block size here. The only requirement is that -- it should not be less than the square root of the group size. -- With 32, we will work on groups of size 1024 or smaller, which -- fits every device Troels has seen. Still, it would be nicer if -- it were a runtime parameter. Some day. let block_size = Imp.ValueExp $ IntValue $ Int32Value 32 simd_width = Imp.sizeToExp $ kernelWaveSize constants block_id = Imp.var local_tid int32 `quot` block_size in_block_id = Imp.var local_tid int32 - block_id * block_size doInBlockScan active = inBlockScan simd_width block_size active local_tid acc_local_mem lid_in_bounds = Imp.var local_tid int32 .<. w' doInBlockScan lid_in_bounds lam sOp Imp.Barrier let last_in_block = in_block_id .==. block_size - 1 sComment "last thread of block 'i' writes its result to offset 'i'" $ sWhen (last_in_block .&&. lid_in_bounds) $ zipWithM_ (writeParamToLocalMemory block_id) acc_local_mem y_params sOp Imp.Barrier let is_first_block = block_id .==. 0 ImpGen.comment "scan the first block, after which offset 'i' contains carry-in for warp 'i+1'" $ doInBlockScan (is_first_block .&&. lid_in_bounds) renamed_lam sOp Imp.Barrier let read_carry_in = zipWithM_ (readParamFromLocalMemory (paramName other_index_param) (block_id - 1)) x_params acc_local_mem let op_to_y = ImpGen.compileBody' y_params $ lambdaBody lam write_final_result = zipWithM_ (writeParamToLocalMemory $ Imp.var local_tid int32) acc_local_mem y_params sComment "carry-in for every block except the first" $ sUnless (is_first_block .||. Imp.UnOpExp Not lid_in_bounds) $ do sComment "read operands" read_carry_in sComment "perform operation" op_to_y sComment "write final result" write_final_result sOp Imp.Barrier sComment "restore correct values for first block" $ sWhen is_first_block write_final_result compileKernelExp constants (Pattern _ final) (GroupStream w maxchunk lam accs _arrs) = do let GroupStreamLambda block_size block_offset acc_params arr_params body = lam block_offset' = Imp.var block_offset int32 w' <- ImpGen.compileSubExp w max_block_size <- ImpGen.compileSubExp maxchunk ImpGen.dLParams (acc_params++arr_params) zipWithM_ ImpGen.compileSubExpTo (map paramName acc_params) accs dPrim_ block_size int32 -- If the GroupStream is morally just a do-loop, generate simpler code. case mapM isSimpleThreadInSpace $ stmsToList $ bodyStms body of Just stms' | ValueExp x <- max_block_size, oneIsh x -> do let body' = body { bodyStms = stmsFromList stms' } body'' = allThreads constants $ ImpGen.compileLoopBody (map paramName acc_params) body' block_size <-- 1 -- Check if loop is candidate for unrolling. let loop = case w of Var w_var | Just w_bound <- lookup w_var $ kernelStreamed constants, w_bound /= Imp.ConstSize 1 -> -- Candidate for unrolling, so generate two loops. sIf (w' .==. Imp.sizeToExp w_bound) (sFor block_offset Int32 (Imp.sizeToExp w_bound) body'') (sFor block_offset Int32 w' body'') _ -> sFor block_offset Int32 w' body'' if kernelThreadActive constants == Imp.ValueExp (BoolValue True) then loop else sWhen (kernelThreadActive constants) loop _ -> do dPrim_ block_offset int32 let body' = streaming constants block_size maxchunk $ ImpGen.compileBody' acc_params body block_offset <-- 0 let not_at_end = block_offset' .<. w' set_block_size = sIf (w' - block_offset' .<. max_block_size) (block_size <-- (w' - block_offset')) (block_size <-- max_block_size) increase_offset = block_offset <-- block_offset' + max_block_size -- Three cases to consider for simpler generated code based -- on max block size: (0) if full input size, do not -- generate a loop; (1) if one, generate for-loop (2) -- otherwise, generate chunked while-loop. if max_block_size == w' then (block_size <-- w') >> body' else if max_block_size == Imp.ValueExp (value (1::Int32)) then do block_size <-- w' sFor block_offset Int32 w' body' else sWhile not_at_end $ set_block_size >> body' >> increase_offset forM_ (zip final acc_params) $ \(pe, p) -> ImpGen.copyDWIM (patElemName pe) [] (Var $ paramName p) [] where isSimpleThreadInSpace (Let _ _ Op{}) = Nothing isSimpleThreadInSpace bnd = Just bnd compileKernelExp _ _ (GroupGenReduce w arrs op bucket values locks) = do -- Check if bucket is in-bounds bucket' <- mapM ImpGen.compileSubExp bucket w' <- mapM ImpGen.compileSubExp w sWhen (indexInBounds bucket' w') $ atomicUpdate arrs bucket op values locking where indexInBounds inds bounds = foldl1 (.&&.) $ zipWith checkBound inds bounds where checkBound ind bound = 0 .<=. ind .&&. ind .<. bound locking = Locking locks 0 1 0 compileKernelExp _ dest e = compilerBugS $ unlines ["Invalid target", " " ++ show dest, "for kernel expression", " " ++ pretty e] -- | Locking strategy used for an atomic update. data Locking = Locking { lockingArray :: VName -- ^ Array containing the lock. , lockingIsUnlocked :: Imp.Exp -- ^ Value for us to consider the lock free. , lockingToLock :: Imp.Exp -- ^ What to write when we lock it. , lockingToUnlock :: Imp.Exp -- ^ What to write when we unlock it. } groupReduce :: ExplicitMemorish lore => KernelConstants -> SubExp -> Lambda lore -> [VName] -> ImpGen.ImpM lore Imp.KernelOp () groupReduce constants w lam arrs = do w' <- ImpGen.compileSubExp w let local_tid = kernelLocalThreadId constants (reduce_i, reduce_j_param, actual_reduce_params) = partitionChunkedKernelLambdaParameters $ lambdaParams lam (reduce_acc_params, reduce_arr_params) = splitAt (length arrs) actual_reduce_params reduce_j = paramName reduce_j_param offset <- dPrim "offset" int32 skip_waves <- dPrim "skip_waves" int32 ImpGen.dLParams $ lambdaParams lam reduce_i <-- Imp.var local_tid int32 let setOffset x = do offset <-- x reduce_j <-- Imp.var local_tid int32 + Imp.var offset int32 setOffset 0 sWhen (Imp.var local_tid int32 .<. w') $ zipWithM_ (readReduceArgument offset) reduce_acc_params arrs let read_reduce_args = zipWithM_ (readReduceArgument offset) reduce_arr_params arrs do_reduce = do ImpGen.comment "read array element" read_reduce_args ImpGen.compileBody' reduce_acc_params $ lambdaBody lam zipWithM_ (writeReduceOpResult local_tid) reduce_acc_params arrs in_wave_reduce = ImpGen.everythingVolatile do_reduce wave_size = Imp.sizeToExp $ kernelWaveSize constants group_size = Imp.sizeToExp $ kernelGroupSize constants wave_id = Imp.var local_tid int32 `quot` wave_size in_wave_id = Imp.var local_tid int32 - wave_id * wave_size num_waves = (group_size + wave_size - 1) `quot` wave_size arg_in_bounds = Imp.var reduce_j int32 .<. w' doing_in_wave_reductions = Imp.var offset int32 .<. wave_size apply_in_in_wave_iteration = (in_wave_id .&. (2 * Imp.var offset int32 - 1)) .==. 0 in_wave_reductions = do setOffset 1 sWhile doing_in_wave_reductions $ do sWhen (arg_in_bounds .&&. apply_in_in_wave_iteration) in_wave_reduce setOffset $ Imp.var offset int32 * 2 doing_cross_wave_reductions = Imp.var skip_waves int32 .<. num_waves is_first_thread_in_wave = in_wave_id .==. 0 wave_not_skipped = (wave_id .&. (2 * Imp.var skip_waves int32 - 1)) .==. 0 apply_in_cross_wave_iteration = arg_in_bounds .&&. is_first_thread_in_wave .&&. wave_not_skipped cross_wave_reductions = do skip_waves <-- 1 sWhile doing_cross_wave_reductions $ do sOp Imp.Barrier setOffset (Imp.var skip_waves int32 * wave_size) sWhen apply_in_cross_wave_iteration do_reduce skip_waves <-- Imp.var skip_waves int32 * 2 in_wave_reductions cross_wave_reductions where readReduceArgument offset param arr | Prim _ <- paramType param = ImpGen.copyDWIM (paramName param) [] (Var arr) [i] | otherwise = return () where i = ImpGen.varIndex (kernelLocalThreadId constants) + ImpGen.varIndex offset writeReduceOpResult i param arr | Prim _ <- paramType param = ImpGen.copyDWIM arr [ImpGen.varIndex i] (Var $ paramName param) [] | otherwise = return () atomicUpdate :: ExplicitMemorish lore => [VName] -> [SubExp] -> Lambda lore -> [SubExp] -> Locking -> ImpGen.ImpM lore Imp.KernelOp () atomicUpdate [a] bucket op [v] _ | [Prim t] <- lambdaReturnType op, primBitSize t == 32 = do -- If we have only one array and one non-array value (this is a -- one-to-one correspondance) then we need only one -- update. If operator has an atomic implementation we use -- that, otherwise it is still a binary operator which can -- be implemented by atomic compare-and-swap if 32 bits. -- Common variables. old <- dPrim "old" t bucket' <- mapM ImpGen.compileSubExp bucket (arr', _a_space, bucket_offset) <- ImpGen.fullyIndexArray a bucket' val' <- ImpGen.compileSubExp v case opHasAtomicSupport old arr' bucket_offset op of Just f -> sOp $ f val' Nothing -> do -- Code generation target: -- -- old = d_his[idx]; -- do { -- assumed = old; -- tmp = OP::apply(val, assumed); -- old = atomicCAS(&d_his[idx], assumed, tmp); -- } while(assumed != old); assumed <- dPrim "assumed" t run_loop <- dPrimV "run_loop" true ImpGen.copyDWIM old [] (Var a) bucket' -- Preparing parameters let (acc_p:arr_p:_) = lambdaParams op -- Critical section ImpGen.dLParams $ lambdaParams op -- While-loop: Try to insert your value let (toBits, fromBits) = case t of FloatType Float32 -> (\x -> Imp.FunExp "to_bits32" [x] int32, \x -> Imp.FunExp "from_bits32" [x] t) _ -> (id, id) sWhile (Imp.var run_loop Bool) $ do assumed <-- Imp.var old t paramName acc_p <-- val' paramName arr_p <-- Imp.var assumed t ImpGen.compileBody' [acc_p] $ lambdaBody op old_bits <- dPrim "old_bits" int32 sOp $ Imp.Atomic $ Imp.AtomicCmpXchg old_bits arr' bucket_offset (toBits (Imp.var assumed int32)) (toBits (Imp.var (paramName acc_p) int32)) old <-- fromBits (Imp.var old_bits int32) sWhen (toBits (Imp.var assumed t) .==. Imp.var old_bits int32) (run_loop <-- false) where opHasAtomicSupport old arr' bucket' lam = do let atomic f = Imp.Atomic . f old arr' bucket' [BasicOp (BinOp bop _ _)] <- Just $ map stmExp $ stmsToList $ bodyStms $ lambdaBody lam atomic <$> Imp.atomicBinOp bop atomicUpdate arrs bucket op values locking = do old <- dPrim "old" int32 loop_done <- dPrimV "loop_done" 0 -- Check if bucket is in-bounds bucket' <- mapM ImpGen.compileSubExp bucket -- Correctly index into locks. (locks', _locks_space, locks_offset) <- ImpGen.fullyIndexArray (lockingArray locking) bucket' -- Preparing parameters let (acc_params, arr_params) = splitAt (length values) $ lambdaParams op -- Critical section let try_acquire_lock = sOp $ Imp.Atomic $ Imp.AtomicCmpXchg old locks' locks_offset (lockingIsUnlocked locking) (lockingToLock locking) lock_acquired = Imp.var old int32 .==. lockingIsUnlocked locking loop_cond = Imp.var loop_done int32 .==. 0 release_lock = ImpGen.everythingVolatile $ ImpGen.sWrite (lockingArray locking) bucket' $ lockingToUnlock locking break_loop = loop_done <-- 1 -- We copy the current value and the new value to the parameters -- unless they are array-typed. If they are arrays, then the -- index functions should already be set up correctly, so there is -- nothing more to do. let bind_acc_params = forM_ (zip acc_params arrs) $ \(acc_p, arr) -> when (primType (paramType acc_p)) $ ImpGen.copyDWIM (paramName acc_p) [] (Var arr) bucket' let bind_arr_params = forM_ (zip arr_params values) $ \(arr_p, val) -> when (primType (paramType arr_p)) $ ImpGen.copyDWIM (paramName arr_p) [] val [] let op_body = ImpGen.compileBody' acc_params $ lambdaBody op do_gen_reduce = zipWithM_ (writeArray bucket') arrs $ map (Var . paramName) acc_params -- While-loop: Try to insert your value sWhile loop_cond $ do try_acquire_lock sWhen lock_acquired $ do ImpGen.dLParams $ lambdaParams op bind_acc_params bind_arr_params op_body do_gen_reduce release_lock break_loop sOp Imp.MemFence where writeArray bucket' arr val = ImpGen.copyDWIM arr bucket' val [] allThreads :: KernelConstants -> InKernelGen () -> InKernelGen () allThreads constants = ImpGen.emit <=< ImpGen.subImpM_ (inKernelOperations constants') where constants' = constants { kernelThreadActive = Imp.ValueExp (BoolValue True) } streaming :: KernelConstants -> VName -> SubExp -> InKernelGen () -> InKernelGen () streaming constants chunksize bound m = do bound' <- ImpGen.subExpToDimSize bound let constants' = constants { kernelStreamed = (chunksize, bound') : kernelStreamed constants } ImpGen.emit =<< ImpGen.subImpM_ (inKernelOperations constants') m compileKernelResult :: KernelConstants -> PatElem InKernel -> KernelResult -> InKernelGen () compileKernelResult constants pe (ThreadsReturn OneResultPerGroup what) = do i <- newVName "i" in_local_memory <- arrayInLocalMemory what let me = Imp.var (kernelLocalThreadId constants) int32 if not in_local_memory then do who' <- ImpGen.compileSubExp $ intConst Int32 0 sWhen (me .==. who') $ ImpGen.copyDWIM (patElemName pe) [ImpGen.varIndex $ kernelGroupId constants] what [] else do -- If the result of the group is an array in local memory, we -- store it by collective copying among all the threads of the -- group. TODO: also do this if the array is in global memory -- (but this is a bit more tricky, synchronisation-wise). -- -- We do the reads/writes multidimensionally, but the loop is -- single-dimensional. ws <- mapM ImpGen.compileSubExp . arrayDims =<< subExpType what -- Compute how many elements this thread is responsible for. -- Formula: (w - ltid) / group_size (rounded up). let w = product ws ltid = ImpGen.varIndex (kernelLocalThreadId constants) group_size = Imp.sizeToExp (kernelGroupSize constants) to_write = (w - ltid) `quotRoundingUp` group_size is = unflattenIndex ws $ ImpGen.varIndex i * group_size + ltid sFor i Int32 to_write $ ImpGen.copyDWIM (patElemName pe) (ImpGen.varIndex (kernelGroupId constants) : is) what is compileKernelResult constants pe (ThreadsReturn AllThreads what) = ImpGen.copyDWIM (patElemName pe) [ImpGen.varIndex $ kernelGlobalThreadId constants] what [] compileKernelResult constants pe (ThreadsReturn (ThreadsPerGroup limit) what) = sWhen (isActive limit) $ ImpGen.copyDWIM (patElemName pe) [ImpGen.varIndex $ kernelGroupId constants] what [] compileKernelResult constants pe (ThreadsReturn ThreadsInSpace what) = do let is = map (ImpGen.varIndex . fst) $ kernelDimensions constants sWhen (kernelThreadActive constants) $ ImpGen.copyDWIM (patElemName pe) is what [] compileKernelResult constants pe (ConcatReturns SplitContiguous _ per_thread_elems moffset what) = do dest_loc <- ImpGen.entryArrayLocation <$> ImpGen.lookupArray (patElemName pe) let dest_loc_offset = ImpGen.offsetArray dest_loc offset dest' = ImpGen.arrayDestination dest_loc_offset ImpGen.copyDWIMDest dest' [] (Var what) [] where offset = case moffset of Nothing -> ImpGen.compileSubExpOfType int32 per_thread_elems * ImpGen.varIndex (kernelGlobalThreadId constants) Just se -> ImpGen.compileSubExpOfType int32 se compileKernelResult constants pe (ConcatReturns (SplitStrided stride) _ _ moffset what) = do dest_loc <- ImpGen.entryArrayLocation <$> ImpGen.lookupArray (patElemName pe) let dest_loc' = ImpGen.strideArray (ImpGen.offsetArray dest_loc offset) $ ImpGen.compileSubExpOfType int32 stride dest' = ImpGen.arrayDestination dest_loc' ImpGen.copyDWIMDest dest' [] (Var what) [] where offset = case moffset of Nothing -> ImpGen.varIndex (kernelGlobalThreadId constants) Just se -> ImpGen.compileSubExpOfType int32 se compileKernelResult constants pe (WriteReturn rws _arr dests) = do rws' <- mapM ImpGen.compileSubExp rws forM_ dests $ \(is, e) -> do is' <- mapM ImpGen.compileSubExp is let condInBounds i rw = 0 .<=. i .&&. i .<. rw write = foldl (.&&.) (kernelThreadActive constants) $ zipWith condInBounds is' rws' sWhen write $ ImpGen.copyDWIM (patElemName pe) (map (ImpGen.compileSubExpOfType int32) is) e [] compileKernelResult _ _ KernelInPlaceReturn{} = -- Already in its place... said it was a hack. return () isActive :: [(VName, SubExp)] -> Imp.Exp isActive limit = case actives of [] -> Imp.ValueExp $ BoolValue True x:xs -> foldl (.&&.) x xs where (is, ws) = unzip limit actives = zipWith active is $ map (ImpGen.compileSubExpOfType Bool) ws active i = (Imp.var i int32 .<.) setSpaceIndices :: KernelSpace -> InKernelGen () setSpaceIndices space = case spaceStructure space of FlatThreadSpace is_and_dims -> flatSpaceWith gtid is_and_dims NestedThreadSpace is_and_dims -> do let (gtids, gdims, ltids, ldims) = unzip4 is_and_dims gdims' <- mapM ImpGen.compileSubExp gdims ldims' <- mapM ImpGen.compileSubExp ldims let (gtid_es, ltid_es) = unzip $ unflattenNestedIndex gdims' ldims' gtid zipWithM_ (<--) gtids gtid_es zipWithM_ (<--) ltids ltid_es where gtid = Imp.var (spaceGlobalId space) int32 flatSpaceWith base is_and_dims = do let (is, dims) = unzip is_and_dims dims' <- mapM ImpGen.compileSubExp dims let index_expressions = unflattenIndex dims' base zipWithM_ (<--) is index_expressions unflattenNestedIndex :: IntegralExp num => [num] -> [num] -> num -> [(num,num)] unflattenNestedIndex global_dims group_dims global_id = zip global_is local_is where num_groups_dims = zipWith quotRoundingUp global_dims group_dims group_size = product group_dims group_id = global_id `Futhark.Util.IntegralExp.quot` group_size local_id = global_id `Futhark.Util.IntegralExp.rem` group_size group_is = unflattenIndex num_groups_dims group_id local_is = unflattenIndex group_dims local_id global_is = zipWith (+) local_is $ zipWith (*) group_is group_dims arrayInLocalMemory :: SubExp -> InKernelGen Bool arrayInLocalMemory (Var name) = do res <- ImpGen.lookupVar name case res of ImpGen.ArrayVar _ entry -> (Space "local"==) . ImpGen.entryMemSpace <$> ImpGen.lookupMemory (ImpGen.memLocationName (ImpGen.entryArrayLocation entry)) _ -> return False arrayInLocalMemory Constant{} = return False