module CmmContFlowOpt
( runCmmOpts, cmmCfgOpts, cmmCfgOptsZ
, branchChainElimZ, removeUnreachableBlocksZ, predMap
- , replaceLabelsZ
+ , replaceLabelsZ, replaceBranches, runCmmContFlowOptsZs
)
where
+import BlockId
import Cmm
import CmmTx
import qualified ZipCfg as G
-import StackSlot
+import ZipCfg
import ZipCfgCmmRep
import Maybes
import Monad
+import Outputable
import Panic
import Prelude hiding (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)
-
+runCmmContFlowOptsZs :: [CmmZ] -> [CmmZ]
+runCmmContFlowOptsZs prog
+ = [ runTx (runCmmOpts cmmCfgOptsZ) cmm_top
+ | cmm_top <- prog ]
-------------------------------------
cmmCfgOpts :: Tx (ListGraph CmmStmt)
cmmCfgOptsZ :: Tx CmmGraph
cmmCfgOpts = branchChainElim -- boring, but will get more exciting later
-cmmCfgOptsZ =
- branchChainElimZ `seqTx` blockConcatZ `seqTx` removeUnreachableBlocksZ
+cmmCfgOptsZ g =
+ (branchChainElimZ `seqTx` blockConcatZ `seqTx` removeUnreachableBlocksZ) g
-- Here branchChainElim can ultimately be replaced
-- with a more exciting combination of optimisations
optGraph _ top@(CmmData {}) = noTx top
optGraph opt (CmmProc info lbl formals g) = fmap (CmmProc info lbl formals) (opt g)
+------------------------------------
+mapProcs :: Tx (GenCmmTop d h s) -> Tx (GenCmm d h s)
+mapProcs f (Cmm tops) = fmap Cmm (mapTx f tops)
+
----------------------------------------------------------------
branchChainElim :: Tx (ListGraph CmmStmt)
--- Remove any basic block of the form L: goto L',
--- and replace L with L' everywhere else
+-- 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.
branchChainElim (ListGraph blocks)
| null lone_branch_blocks -- No blocks to remove
= noTx (ListGraph 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!
+ -- An infinite loop is not a link in a branch chain!
replaceLabels :: BlockEnv BlockId -> CmmBasicBlock -> CmmBasicBlock
replaceLabels env (BasicBlock id stmts)
branchChainElimZ :: Tx CmmGraph
-- Remove any basic block of the form L: goto L',
-- and replace L with L' everywhere else
-branchChainElimZ g@(G.LGraph eid _)
+branchChainElimZ g@(G.LGraph eid args _)
| null lone_branch_blocks -- No blocks to remove
= noTx g
| otherwise
- = aTx $ replaceLabelsZ env $ G.of_block_list eid (self_branches ++ others)
+ = aTx $ replaceLabelsZ env $ G.of_block_list eid args (self_branches ++ others)
where
(lone_branch_blocks, others) = partitionWith isLoneBranchZ (G.to_block_list g)
- env = mkClosureBlockEnv lone_branch_blocks
+ env = mkClosureBlockEnvZ 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
+ let loop_to (id, _) =
+ if lookup id == id then
+ Just (G.Block id emptyStackInfo (G.ZLast (G.mkBranchNode id)))
+ else
+ Nothing
+ in mapMaybe loop_to lone_branch_blocks
lookup id = lookupBlockEnv env id `orElse` id
+-- Be careful not to mark a block as a lone branch if it carries
+-- important information about incoming arguments or the update frame.
isLoneBranchZ :: CmmBlock -> Either (BlockId, BlockId) CmmBlock
-isLoneBranchZ (G.Block id (G.ZLast (G.LastOther (LastBranch target))))
+isLoneBranchZ (G.Block id (StackInfo {argBytes = Nothing, returnOff = Nothing})
+ (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!
+ -- An infinite loop is not a link in a branch chain!
replaceLabelsZ :: BlockEnv BlockId -> CmmGraph -> CmmGraph
-replaceLabelsZ env = replace_eid . G.map_nodes id id last
+replaceLabelsZ env = replace_eid . G.map_nodes id middle last
where
- replace_eid (G.LGraph eid blocks) = G.LGraph (lookup eid) blocks
- last (LastBranch id) = LastBranch (lookup id)
- last (LastCondBranch e ti fi) = LastCondBranch e (lookup ti) (lookup fi)
- last (LastSwitch e tbl) = LastSwitch e (map (fmap lookup) tbl)
- last (LastCall tgt (Just id)) = LastCall tgt (Just $ lookup id)
- last exit_jump_return = exit_jump_return
- lookup id = lookupBlockEnv env id `orElse` id
+ replace_eid (G.LGraph eid off blocks) = G.LGraph (lookup eid) off blocks
+ middle = mapExpDeepMiddle exp
+ last l = mapExpDeepLast exp (last' l)
+ last' (LastBranch bid) = LastBranch (lookup bid)
+ last' (LastCondBranch p t f) = LastCondBranch p (lookup t) (lookup f)
+ last' (LastSwitch e arms) = LastSwitch e (map (liftM lookup) arms)
+ last' (LastCall t k a r) = LastCall t (liftM lookup k) a r
+ exp (CmmLit (CmmBlock bid)) = CmmLit (CmmBlock (lookup bid))
+ exp (CmmStackSlot (CallArea (Young id)) i) =
+ CmmStackSlot (CallArea (Young (lookup id))) i
+ exp e = e
+ lookup id = fmap lookup (lookupBlockEnv env id) `orElse` id
+
+replaceBranches :: BlockEnv BlockId -> CmmGraph -> CmmGraph
+replaceBranches env g = map_nodes id id last g
+ where
+ last (LastBranch id) = LastBranch (lookup id)
+ last (LastCondBranch e ti fi) = LastCondBranch e (lookup ti) (lookup fi)
+ last (LastSwitch e tbl) = LastSwitch e (map (fmap lookup) tbl)
+ last l@(LastCall {}) = l
+ lookup id = fmap lookup (lookupBlockEnv env id) `orElse` id
----------------------------------------------------------------
-- Build a map from a block to its set of predecessors. Very useful.
predMap :: G.LastNode l => G.LGraph m l -> BlockEnv BlockSet
predMap g = G.fold_blocks add_preds emptyBlockEnv g -- find the back edges
where add_preds b env = foldl (add b) env (G.succs b)
- add (G.Block bid _) env b' =
+ add (G.Block bid _ _) env b' =
extendBlockEnv env b' $
extendBlockSet (lookupBlockEnv env b' `orElse` emptyBlockSet) bid
----------------------------------------------------------------
-blockConcatZ :: Tx CmmGraph
-- If a block B branches to a label L, and L has no other predecessors,
-- then we can splice the block starting with L onto the end of B.
-- Because this optmization can be inhibited by unreachable blocks,
--- we bundle it with a pass that drops unreachable blocks.
+-- we first take a pass to drops unreachable blocks.
-- Order matters, so we work bottom up (reverse postorder DFS).
+--
+-- 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.
-blockConcatZ = removeUnreachableBlocksZ `seqTx` blockConcatZ'
+blockConcatZ :: Tx CmmGraph
+blockConcatZ = removeUnreachableBlocksZ `seqTx` blockConcatZ'
blockConcatZ' :: Tx CmmGraph
-blockConcatZ' g@(G.LGraph eid blocks) = tx $ G.LGraph eid blocks'
- where (changed, blocks') = foldr maybe_concat (False, blocks) $ G.postorder_dfs g
- maybe_concat b@(G.Block bid _) (changed, blocks') =
- let unchanged = (changed, extendBlockEnv blocks' bid b)
+blockConcatZ' g@(G.LGraph eid off blocks) =
+ tx $ replaceLabelsZ concatMap $ G.LGraph eid off blocks'
+ where (changed, blocks', concatMap) =
+ foldr maybe_concat (False, blocks, emptyBlockEnv) $ G.postorder_dfs g
+ maybe_concat b@(G.Block bid _ _) (changed, blocks', concatMap) =
+ let unchanged = (changed, extendBlockEnv blocks' bid b, concatMap)
in case G.goto_end $ G.unzip b of
(h, G.LastOther (LastBranch b')) ->
- if num_preds b' == 1 then
- (True, extendBlockEnv blocks' bid $ splice blocks' h b')
+ if canConcatWith b' then
+ (True, extendBlockEnv blocks' bid $ splice blocks' h b',
+ extendBlockEnv concatMap b' bid)
else unchanged
_ -> unchanged
num_preds bid = liftM sizeBlockSet (lookupBlockEnv backEdges bid) `orElse` 0
+ canConcatWith b' =
+ case lookupBlockEnv blocks b' of
+ Just (G.Block _ (StackInfo {returnOff = Nothing}) _) -> num_preds b' == 1
+ _ -> False
backEdges = predMap g
splice blocks' h bid' =
case lookupBlockEnv blocks' bid' of
- Just (G.Block _ t) -> G.zip $ G.ZBlock h t
- Nothing -> panic "unknown successor block"
+ Just (G.Block _ (StackInfo {returnOff = Nothing}) t) ->
+ G.zip $ G.ZBlock h t
+ Just (G.Block _ _ _) ->
+ panic "trying to concatenate but successor block has incoming args"
+ Nothing -> pprPanic "unknown successor block" (ppr bid' <+> ppr blocks' <+> ppr blocks)
tx = if changed then aTx else noTx
----------------------------------------------------------------
mkClosureBlockEnv :: [(BlockId, BlockId)] -> BlockEnv BlockId
endChain orig id = case lookupBlockEnv singleEnv id of
Just id' | id /= orig -> endChain orig id'
_ -> id
+mkClosureBlockEnvZ :: [(BlockId, BlockId)] -> BlockEnv BlockId
+mkClosureBlockEnvZ blocks = mkBlockEnv $ map follow blocks
+ where singleEnv = mkBlockEnv blocks
+ follow (id, next) = (id, endChain id next)
+ endChain orig id = case lookupBlockEnv singleEnv id 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
+removeUnreachableBlocksZ g@(G.LGraph id off blocks) =
+ if length blocks' < sizeBEnv blocks then aTx $ G.of_block_list id off blocks'
+ else noTx g
where blocks' = G.postorder_dfs g
projects / ghc-hetmet.git / blobdiff