-{-# OPTIONS -Wall -fno-warn-name-shadowing #-}
+{-# LANGUAGE GADTs #-}
+{-# OPTIONS_GHC -fno-warn-warnings-deprecations -fno-warn-incomplete-patterns #-}
+
module CmmContFlowOpt
- ( runCmmOpts, cmmCfgOpts, cmmCfgOptsZ
- , branchChainElimZ, removeUnreachableBlocksZ
+ ( runCmmOpts, oldCmmCfgOpts, cmmCfgOpts
+ , branchChainElim, removeUnreachableBlocks, predMap
+ , replaceLabels, replaceBranches, runCmmContFlowOpts
)
where
+import BlockId
import Cmm
-import CmmTx
-import qualified ZipCfg as G
-import ZipCfgCmm
+import CmmDecl
+import CmmExpr
+import qualified OldCmm as Old
+
import Maybes
+import Compiler.Hoopl
+import Control.Monad
+import Outputable
+import Prelude hiding (succ, unzip, zip)
import Util
-import UniqFM
------------------------------------
-mapProcs :: Tx (GenCmmTop d h s) -> Tx (GenCmm d h s)
-mapProcs f (Cmm tops) = fmap Cmm (mapTx f tops)
+runCmmContFlowOpts :: Cmm -> Cmm
+runCmmContFlowOpts prog = runCmmOpts cmmCfgOpts prog
+oldCmmCfgOpts :: Old.ListGraph Old.CmmStmt -> Old.ListGraph Old.CmmStmt
+cmmCfgOpts :: CmmGraph -> CmmGraph
-------------------------------------
-cmmCfgOpts :: Tx (ListGraph CmmStmt)
-cmmCfgOptsZ :: Tx CmmGraph
-
-cmmCfgOpts = branchChainElim -- boring, but will get more exciting later
-cmmCfgOptsZ = branchChainElimZ `seqTx` removeUnreachableBlocksZ
+oldCmmCfgOpts = oldBranchChainElim -- boring, but will get more exciting later
+cmmCfgOpts =
+ removeUnreachableBlocks . blockConcat . branchChainElim
-- Here branchChainElim can ultimately be replaced
-- with a more exciting combination of optimisations
-runCmmOpts :: Tx g -> Tx (GenCmm d h g)
-runCmmOpts opt = mapProcs (optGraph opt)
+runCmmOpts :: (g -> g) -> GenCmm d h g -> GenCmm d h g
+-- Lifts a transformer on a single graph to one on the whole program
+runCmmOpts opt = mapProcs (optProc opt)
+
+optProc :: (g -> g) -> GenCmmTop d h g -> GenCmmTop d h g
+optProc _ top@(CmmData {}) = top
+optProc opt (CmmProc info lbl g) = CmmProc info lbl (opt g)
-optGraph :: Tx g -> Tx (GenCmmTop d h g)
-optGraph _ top@(CmmData {}) = noTx top
-optGraph opt (CmmProc info lbl formals g) = fmap (CmmProc info lbl formals) (opt g)
+------------------------------------
+mapProcs :: (GenCmmTop d h s -> GenCmmTop d h s) -> GenCmm d h s -> GenCmm d h s
+mapProcs f (Cmm tops) = Cmm (map f tops)
----------------------------------------------------------------
-branchChainElim :: Tx (ListGraph CmmStmt)
--- Remove any basic block of the form L: goto L',
--- and replace L with L' everywhere else
-branchChainElim (ListGraph blocks)
+oldBranchChainElim :: Old.ListGraph Old.CmmStmt -> Old.ListGraph Old.CmmStmt
+-- If L is not captured in an instruction, we can remove any
+-- basic block of the form L: goto L', and replace L with L' everywhere else.
+-- How does L get captured? In a CallArea.
+oldBranchChainElim (Old.ListGraph blocks)
| null lone_branch_blocks -- No blocks to remove
- = noTx (ListGraph blocks)
+ = Old.ListGraph blocks
| otherwise
- = aTx (ListGraph new_blocks)
+ = Old.ListGraph new_blocks
where
(lone_branch_blocks, others) = partitionWith isLoneBranch blocks
new_blocks = map (replaceLabels env) others
env = mkClosureBlockEnv lone_branch_blocks
-isLoneBranch :: CmmBasicBlock -> Either (BlockId, BlockId) CmmBasicBlock
-isLoneBranch (BasicBlock id [CmmBranch target]) | id /= target = Left (id, target)
-isLoneBranch other_block = Right other_block
- -- ^ An infinite loop is not a link in a branch chain!
+ isLoneBranch :: Old.CmmBasicBlock -> Either (BlockId, BlockId) Old.CmmBasicBlock
+ isLoneBranch (Old.BasicBlock id [Old.CmmBranch target]) | id /= target = Left (id, target)
+ isLoneBranch other_block = Right other_block
+ -- An infinite loop is not a link in a branch chain!
-replaceLabels :: BlockEnv BlockId -> CmmBasicBlock -> CmmBasicBlock
-replaceLabels env (BasicBlock id stmts)
- = BasicBlock id (map replace stmts)
- where
- replace (CmmBranch id) = CmmBranch (lookup id)
- replace (CmmCondBranch e id) = CmmCondBranch e (lookup id)
- replace (CmmSwitch e tbl) = CmmSwitch e (map (fmap lookup) tbl)
- replace other_stmt = other_stmt
+ replaceLabels :: BlockEnv BlockId -> Old.CmmBasicBlock -> Old.CmmBasicBlock
+ replaceLabels env (Old.BasicBlock id stmts)
+ = Old.BasicBlock id (map replace stmts)
+ where
+ replace (Old.CmmBranch id) = Old.CmmBranch (lookup id)
+ replace (Old.CmmCondBranch e id) = Old.CmmCondBranch e (lookup id)
+ replace (Old.CmmSwitch e tbl) = Old.CmmSwitch e (map (fmap lookup) tbl)
+ replace other_stmt = other_stmt
+
+ lookup id = mapLookup id env `orElse` id
- lookup id = lookupBlockEnv env id `orElse` id
----------------------------------------------------------------
-branchChainElimZ :: Tx CmmGraph
+branchChainElim :: CmmGraph -> CmmGraph
-- Remove any basic block of the form L: goto L',
--- and replace L with L' everywhere else
-branchChainElimZ g@(G.LGraph eid _)
+-- and replace L with L' everywhere else,
+-- unless L is the successor of a call instruction and L'
+-- is the entry block. You don't want to set the successor
+-- of a function call to the entry block because there is no good way
+-- to store both the infotables for the call and from the callee,
+-- while putting the stack pointer in a consistent place.
+--
+-- JD isn't quite sure when it's safe to share continuations for different
+-- function calls -- have to think about where the SP will be,
+-- so we'll table that problem for now by leaving all call successors alone.
+branchChainElim g
| null lone_branch_blocks -- No blocks to remove
- = noTx g
+ = g
| otherwise
- = aTx $ replaceLabelsZ env $ G.of_block_list eid (self_branches ++ others)
+ = replaceLabels env $ ofBlockList (g_entry g) (self_branches ++ others)
where
- (lone_branch_blocks, others) = partitionWith isLoneBranchZ (G.to_block_list g)
+ blocks = toBlockList g
+ (lone_branch_blocks, others) = partitionWith isLoneBranch blocks
env = mkClosureBlockEnv lone_branch_blocks
self_branches =
- let loop_to (id, _) =
- if lookup id == id then
- Just (G.Block id (G.ZLast (G.mkBranchNode id)))
- else
- Nothing
- in mapMaybe loop_to lone_branch_blocks
- lookup id = G.lookupBlockEnv env id `orElse` id
-
-isLoneBranchZ :: CmmBlock -> Either (G.BlockId, G.BlockId) CmmBlock
-isLoneBranchZ (G.Block id (G.ZLast (G.LastOther (LastBranch target []))))
- | id /= target = Left (id,target)
-isLoneBranchZ other = Right other
- -- ^ An infinite loop is not a link in a branch chain!
-
-replaceLabelsZ :: BlockEnv G.BlockId -> CmmGraph -> CmmGraph
-replaceLabelsZ env = replace_eid . G.map_nodes id id last
+ let loop_to (id, _) =
+ if lookup id == id then
+ Just $ blockOfNodeList (JustC (CmmEntry id), [], JustC (mkBranchNode id))
+ else
+ Nothing
+ in mapMaybe loop_to lone_branch_blocks
+ lookup id = mapLookup id env `orElse` id
+
+ call_succs = foldl add emptyBlockSet blocks
+ where add :: BlockSet -> CmmBlock -> BlockSet
+ add succs b =
+ case lastNode b of
+ (CmmCall _ (Just k) _ _ _) -> setInsert k succs
+ (CmmForeignCall {succ=k}) -> setInsert k succs
+ _ -> succs
+ isLoneBranch :: CmmBlock -> Either (BlockId, BlockId) CmmBlock
+ isLoneBranch block | (JustC (CmmEntry id), [], JustC (CmmBranch target)) <- blockToNodeList block,
+ id /= target && not (setMember id call_succs)
+ = Left (id,target)
+ isLoneBranch other = Right other
+ -- An infinite loop is not a link in a branch chain!
+
+maybeReplaceLabels :: (CmmNode O C -> Bool) -> BlockEnv BlockId -> CmmGraph -> CmmGraph
+maybeReplaceLabels lpred env =
+ replace_eid . mapGraphNodes (id, middle, last)
+ where
+ replace_eid g = g {g_entry = lookup (g_entry g)}
+ lookup id = fmap lookup (mapLookup id env) `orElse` id
+
+ middle = mapExpDeep exp
+ last l = if lpred l then mapExpDeep exp (last' l) else l
+ last' :: CmmNode O C -> CmmNode O C
+ last' (CmmBranch bid) = CmmBranch (lookup bid)
+ last' (CmmCondBranch p t f) = CmmCondBranch p (lookup t) (lookup f)
+ last' (CmmSwitch e arms) = CmmSwitch e (map (liftM lookup) arms)
+ last' (CmmCall t k a res r) = CmmCall t (liftM lookup k) a res r
+ last' (CmmForeignCall t r a bid u i) = CmmForeignCall t r a (lookup bid) u i
+
+ exp (CmmLit (CmmBlock bid)) = CmmLit (CmmBlock (lookup bid))
+ exp (CmmStackSlot (CallArea (Young id)) i) = CmmStackSlot (CallArea (Young (lookup id))) i
+ exp e = e
+
+
+replaceLabels :: BlockEnv BlockId -> CmmGraph -> CmmGraph
+replaceLabels = maybeReplaceLabels (const True)
+
+replaceBranches :: BlockEnv BlockId -> CmmGraph -> CmmGraph
+replaceBranches env g = mapGraphNodes (id, id, last) g
where
- replace_eid (G.LGraph eid blocks) = G.LGraph (lookup eid) blocks
- last (LastBranch id args) = LastBranch (lookup id) args
- last (LastCondBranch e ti fi) = LastCondBranch e (lookup ti) (lookup fi)
- last (LastSwitch e tbl) = LastSwitch e (map (fmap lookup) tbl)
- last (LastCall tgt args (Just id)) = LastCall tgt args (Just $ lookup id)
- last exit_jump_return = exit_jump_return
- lookup id = G.lookupBlockEnv env id `orElse` id
+ last :: CmmNode O C -> CmmNode O C
+ last (CmmBranch id) = CmmBranch (lookup id)
+ last (CmmCondBranch e ti fi) = CmmCondBranch e (lookup ti) (lookup fi)
+ last (CmmSwitch e tbl) = CmmSwitch e (map (fmap lookup) tbl)
+ last l@(CmmCall {}) = l
+ last l@(CmmForeignCall {}) = l
+ lookup id = fmap lookup (mapLookup id env) `orElse` id
+
+----------------------------------------------------------------
+-- Build a map from a block to its set of predecessors. Very useful.
+predMap :: [CmmBlock] -> BlockEnv BlockSet
+predMap blocks = foldr add_preds mapEmpty blocks -- find the back edges
+ where add_preds block env = foldl (add (entryLabel block)) env (successors block)
+ add bid env b' =
+ mapInsert b' (setInsert bid (mapLookup b' env `orElse` setEmpty)) env
+----------------------------------------------------------------
+-- If a block B branches to a label L, L is not the entry block,
+-- and L has no other predecessors,
+-- then we can splice the block starting with L onto the end of B.
+-- Order matters, so we work bottom up (reverse postorder DFS).
+-- This optimization can be inhibited by unreachable blocks, but
+-- the reverse postorder DFS returns only reachable blocks.
+--
+-- To ensure correctness, we have to make sure that the BlockId of the block
+-- we are about to eliminate is not named in another instruction.
+--
+-- Note: This optimization does _not_ subsume branch chain elimination.
+blockConcat :: CmmGraph -> CmmGraph
+blockConcat g@(CmmGraph {g_entry=eid}) =
+ replaceLabels concatMap $ ofBlockMap (g_entry g) blocks'
+ where blocks = postorderDfs g
+ (blocks', concatMap) =
+ foldr maybe_concat (toBlockMap g, mapEmpty) $ blocks
+ maybe_concat :: CmmBlock -> (LabelMap CmmBlock, LabelMap Label) -> (LabelMap CmmBlock, LabelMap Label)
+ maybe_concat b unchanged@(blocks', concatMap) =
+ let bid = entryLabel b
+ in case blockToNodeList b of
+ (JustC h, m, JustC (CmmBranch b')) ->
+ if canConcatWith b' then
+ (mapInsert bid (splice blocks' h m b') blocks',
+ mapInsert b' bid concatMap)
+ else unchanged
+ _ -> unchanged
+ num_preds bid = liftM setSize (mapLookup bid backEdges) `orElse` 0
+ canConcatWith b' = b' /= eid && num_preds b' == 1
+ backEdges = predMap blocks
+ splice :: forall map n e x.
+ IsMap map =>
+ map (Block n e x) -> n C O -> [n O O] -> KeyOf map -> Block n C x
+ splice blocks' h m bid' =
+ case mapLookup bid' blocks' of
+ Nothing -> panic "unknown successor block"
+ Just block | (_, m', l') <- blockToNodeList block -> blockOfNodeList (JustC h, (m ++ m'), l')
----------------------------------------------------------------
mkClosureBlockEnv :: [(BlockId, BlockId)] -> BlockEnv BlockId
-mkClosureBlockEnv blocks = mkBlockEnv $ map follow blocks
- where singleEnv = mkBlockEnv blocks
+mkClosureBlockEnv blocks = mapFromList $ map follow blocks
+ where singleEnv = mapFromList blocks :: BlockEnv BlockId
follow (id, next) = (id, endChain id next)
- endChain orig id = case lookupBlockEnv singleEnv id of
+ endChain orig id = case mapLookup id singleEnv of
Just id' | id /= orig -> endChain orig id'
_ -> id
----------------------------------------------------------------
-removeUnreachableBlocksZ :: Tx CmmGraph
-removeUnreachableBlocksZ g@(G.LGraph id blocks) =
- if length blocks' < sizeUFM blocks then aTx $ G.of_block_list id blocks'
- else noTx g
- where blocks' = G.postorder_dfs g
+removeUnreachableBlocks :: CmmGraph -> CmmGraph
+removeUnreachableBlocks g =
+ if length blocks < mapSize (toBlockMap g) then ofBlockList (g_entry g) blocks
+ else g
+ where blocks = postorderDfs g
projects / ghc-hetmet.git / blobdiff