diff options
Diffstat (limited to 'compiler/cmm/CmmContFlowOpt.hs')
| -rw-r--r-- | compiler/cmm/CmmContFlowOpt.hs | 108 |
1 files changed, 74 insertions, 34 deletions
diff --git a/compiler/cmm/CmmContFlowOpt.hs b/compiler/cmm/CmmContFlowOpt.hs index 6909250efb..320b1e7871 100644 --- a/compiler/cmm/CmmContFlowOpt.hs +++ b/compiler/cmm/CmmContFlowOpt.hs @@ -2,7 +2,7 @@ module CmmContFlowOpt ( runCmmOpts, cmmCfgOpts, cmmCfgOptsZ , branchChainElimZ, removeUnreachableBlocksZ, predMap - , replaceLabelsZ + , replaceLabelsZ, runCmmContFlowOptsZs ) where @@ -10,27 +10,28 @@ import BlockId import Cmm import CmmTx import qualified ZipCfg as G +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 = branchChainElimZ `seqTx` blockConcatZ `seqTx` removeUnreachableBlocksZ -- Here branchChainElim can ultimately be replaced -- with a more exciting combination of optimisations @@ -41,10 +42,15 @@ 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 :: 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) @@ -74,73 +80,100 @@ 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))) + Just (G.Block id Nothing (G.ZLast (G.mkBranchNode id))) else Nothing in mapMaybe loop_to lone_branch_blocks lookup id = lookupBlockEnv env id `orElse` id isLoneBranchZ :: CmmBlock -> Either (BlockId, BlockId) CmmBlock -isLoneBranchZ (G.Block id (G.ZLast (G.LastOther (LastBranch target)))) +isLoneBranchZ (G.Block id 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 :: 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 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 + exp (CmmStackSlot (CallArea (Young id)) i) = + CmmStackSlot (CallArea (Young (lookup id))) i + exp e@(CmmStackSlot _ _) = e + 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 +-- (except an adjacent stack pointer adjustment, which we expect and also eliminate). +-- For +-- -- 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 $ pprTrace "concatMap" (ppr concatMap) $ 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') + (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 backEdges = predMap g splice blocks' h bid' = case lookupBlockEnv blocks' bid' of - Just (G.Block _ t) -> G.zip $ G.ZBlock h t + Just (G.Block _ Nothing t) -> G.zip $ G.ZBlock h t + Just (G.Block _ (Just _) _) -> + panic "trying to concatenate but successor block has incoming args" Nothing -> panic "unknown successor block" tx = if changed then aTx else noTx ---------------------------------------------------------------- @@ -151,9 +184,16 @@ mkClosureBlockEnv blocks = mkBlockEnv $ map follow blocks 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' +removeUnreachableBlocksZ g@(G.LGraph id off blocks) = + if length blocks' < sizeUFM blocks then aTx $ G.of_block_list id off blocks' else noTx g where blocks' = G.postorder_dfs g |