module CmmContFlowOpt
( runCmmOpts, cmmCfgOpts, cmmCfgOptsZ
, branchChainElimZ, removeUnreachableBlocksZ, predMap
- , replaceLabelsZ, runCmmContFlowOptsZs
+ , replaceLabelsZ, replaceBranches, runCmmContFlowOptsZs
)
where
import Panic
import Prelude hiding (unzip, zip)
import Util
-import UniqFM
------------------------------------
runCmmContFlowOptsZs :: [CmmZ] -> [CmmZ]
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
(lone_branch_blocks, others) = partitionWith isLoneBranchZ (G.to_block_list g)
env = mkClosureBlockEnvZ lone_branch_blocks
self_branches =
- let loop_to (id, _) =
- if lookup id == id then
- Just (G.Block id Nothing (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 Nothing (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!
replaceLabelsZ env = replace_eid . G.map_nodes id middle last
where
replace_eid (G.LGraph eid off blocks) = G.LGraph (lookup eid) off blocks
- middle m@(MidComment _) = m
- middle (MidAssign r e) = MidAssign r (exp e)
- middle (MidStore addr e) = MidStore (exp addr) (exp e)
- middle (MidUnsafeCall tgt fs as) = MidUnsafeCall (midcall tgt) fs (map exp as)
- middle (MidAddToContext e es) = MidAddToContext (exp e) (map exp es)
- last (LastBranch id) = LastBranch (lookup id)
- last (LastCondBranch e ti fi) = LastCondBranch (exp e) (lookup ti) (lookup fi)
- last (LastSwitch e tbl) = LastSwitch (exp e) (map (fmap lookup) tbl)
- last (LastCall tgt mb_id s) = LastCall (exp tgt) (fmap lookup mb_id) s
- last (LastJump e s) = LastJump (exp e) s
- last (LastReturn s) = LastReturn s
- midcall (ForeignTarget e c) = ForeignTarget (exp e) c
- midcall m@(PrimTarget _) = m
- exp e@(CmmLit _) = e
- exp (CmmLoad addr ty) = CmmLoad (exp addr) ty
- exp e@(CmmReg _) = e
- exp (CmmMachOp op es) = CmmMachOp op $ map exp es
- exp e@(CmmRegOff _ _) = e
+ 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@(CmmStackSlot _ _) = e
+ 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
----------------------------------------------------------------
-- 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
--- (except an adjacent stack pointer adjustment, which we expect and also eliminate).
--- For
+-- we are about to eliminate is not named in another instruction.
--
-- Note: This optimization does _not_ subsume branch chain elimination.
blockConcatZ :: Tx CmmGraph
blockConcatZ = removeUnreachableBlocksZ `seqTx` blockConcatZ'
blockConcatZ' :: Tx CmmGraph
blockConcatZ' g@(G.LGraph eid off blocks) =
- tx $ pprTrace "concatMap" (ppr concatMap) $ replaceLabelsZ concatMap $ 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
+ 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 _ Nothing t) -> G.zip $ G.ZBlock h t
- Just (G.Block _ (Just _) _) ->
+ 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 -> panic "unknown successor block"
+ Nothing -> pprPanic "unknown successor block" (ppr bid' <+> ppr blocks' <+> ppr blocks)
tx = if changed then aTx else noTx
----------------------------------------------------------------
mkClosureBlockEnv :: [(BlockId, BlockId)] -> BlockEnv BlockId
----------------------------------------------------------------
removeUnreachableBlocksZ :: Tx CmmGraph
removeUnreachableBlocksZ g@(G.LGraph id off blocks) =
- if length blocks' < sizeUFM blocks then aTx $ G.of_block_list id off blocks'
- else noTx g
+ 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