{-# LANGUAGE ScopedTypeVariables #-}
module ZipCfg
( -- These data types and names are carefully thought out
- BlockId(..), freshBlockId -- ToDo: BlockId should be abstract,
- -- but it isn't yet
+ BlockId(..) -- ToDo: BlockId should be abstract, but it isn't yet
, BlockEnv, emptyBlockEnv, lookupBlockEnv, extendBlockEnv, insertBlock, mkBlockEnv
, BlockSet, emptyBlockSet, elemBlockSet, extendBlockSet, mkBlockSet
, Graph(..), LGraph(..), FGraph(..)
-- Observers and transformers
-- (open to renaming suggestions here)
, blockId, zip, unzip, last, goto_end, zipht, tailOfLast
- , remove_entry_label
- , splice_tail, splice_head, splice_head_only
+ , splice_tail, splice_head, splice_head_only', splice_head'
, of_block_list, to_block_list
, map_nodes
- , postorder_dfs
+ , postorder_dfs, postorder_dfs_from, postorder_dfs_from_except
, fold_layout
, fold_blocks
, translate
- , pprLgraph
+ , pprLgraph, pprGraph
+
+ , entry -- exported for the convenience of ZipDataflow, at least for now
{-
-- the following functions might one day be useful and can be found
import Unique
import UniqFM
import UniqSet
-import UniqSupply
import Maybe
import Prelude hiding (zip, unzip, last)
There are three types because each type offers a slightly different
invariant or cost model.
- * The distinguished entry of a Graph has no label. Because labels must
- be unique, acquiring one requires a monadic operation ('freshBlockId').
- The primary advantage of the Graph representation is that we can build
- a small Graph purely functionally, without entering a monad. For
- example, during optimization we can easily rewrite a single middle
- node into a Graph containing a sequence of two middle nodes followed by
- LastExit.
+ * The distinguished entry of a Graph has no label. Because labels must be
+ unique, acquiring one requires a supply of Unique labels (BlockId's).
+ The primary advantage of the Graph representation is that we can build a
+ small Graph purely functionally, without needing a fresh BlockId or
+ Unique. For example, during optimization we can easily rewrite a single
+ middle node into a Graph containing a sequence of two middle nodes
+ followed by LastExit.
* In an LGraph, every basic block is labelled. The primary advantage of
this representation is its simplicity: each basic block can be treated
-- | Blocks and flow graphs; see Note [Kinds of graphs]
data Block m l = Block BlockId (ZTail m l)
-data Graph m l = Graph (ZTail m l) (BlockEnv (Block m l))
+data Graph m l = Graph { g_entry :: (ZTail m l), g_blocks :: (BlockEnv (Block m l)) }
data LGraph m l = LGraph { lg_entry :: BlockId
, lg_blocks :: BlockEnv (Block m l) }
---- Utility functions ---
--- | The string argument to 'freshBlockId' was originally helpful in debugging the Quick C--
--- compiler, so I have kept it here even though at present it is thrown away at
--- this spot---there's no reason a BlockId couldn't one day carry a string.
-freshBlockId :: String -> UniqSM BlockId
-
blockId :: Block m l -> BlockId
zip :: ZBlock m l -> Block m l
unzip :: Block m l -> ZBlock m l
-- , (???, [<blocks>,
-- N: y:=x; return (y,x)])
-splice_head :: ZHead m -> LGraph m l -> (LGraph m l, ZHead m)
-splice_tail :: LGraph m l -> ZTail m l -> (ZTail m l, LGraph m l)
+splice_head :: ZHead m -> LGraph m l -> (LGraph m l, ZHead m)
+splice_head' :: ZHead m -> Graph m l -> (BlockEnv (Block m l), ZHead m)
+splice_tail :: Graph m l -> ZTail m l -> Graph m l
--- | We can also splice a single-entry, no-exit LGraph into a head.
+-- | We can also splice a single-entry, no-exit Graph into a head.
splice_head_only :: ZHead m -> LGraph m l -> LGraph m l
+splice_head_only' :: ZHead m -> Graph m l -> LGraph m l
+
--- | Finally, we can remove the entry label of an LGraph and remove
--- it, leaving a Graph:
-remove_entry_label :: LGraph m l -> Graph m l
+-- | A safe operation
-- | Conversion to and from the environment form is convenient. For
-- layout or dataflow, however, one will want to use 'postorder_dfs'
instance LastNode l => HavingSuccessors (Block m l) where
succs b = succs (unzip b)
+instance LastNode l => HavingSuccessors (ZTail m l) where
+ succs b = succs (lastTail b)
+
+
-- ================ IMPLEMENTATION ================--
blockId (Block id _) = id
-freshBlockId _ = do { u <- getUniqueUs; return $ BlockId u }
-
-- | Convert block between forms.
-- These functions are tail-recursive, so we can go as deep as we like
-- without fear of stack overflow.
head_id (ZFirst id) = id
head_id (ZHead h _) = head_id h
-last (ZBlock _ t) = lastt t
- where lastt (ZLast l) = l
- lastt (ZTail _ t) = lastt t
+last (ZBlock _ t) = lastTail t
+
+lastTail :: ZTail m l -> ZLast l
+lastTail (ZLast l) = l
+lastTail (ZTail _ t) = lastTail t
tailOfLast l = ZLast (LastOther l) -- ^ tedious to write in every client
LastExit -> count + (1 :: Int)
_ -> count
+-- | Used in assertions; tells if a graph has exactly one exit
+single_exitg :: Graph l m -> Bool
+single_exitg (Graph tail blocks) = foldUFM add (exit_count (lastTail tail)) blocks == 1
+ where add block count = count + exit_count (last (unzip block))
+ exit_count LastExit = 1 :: Int
+ exit_count _ = 0
+
------------------ graph traversals
-- | This is the most important traversal over this data structure. It drops
-- Then ordinary dfs would give [A,B,D,C] which has a back ref from C to D.
-- Better to geot [A,B,C,D]
--- postorder_dfs :: LastNode l => LGraph m l -> [Block m l]
-postorder_dfs g@(LGraph _ blocks) =
+
+postorder_dfs' :: LastNode l => LGraph m l -> [Block m l]
+postorder_dfs' g@(LGraph _ blocks) =
let FGraph _ eblock _ = entry g
in vnode (zip eblock) (\acc _visited -> acc) [] emptyBlockSet
where
Just b -> b : rst
Nothing -> rst
+postorder_dfs g@(LGraph _ blockenv) =
+ let FGraph id eblock _ = entry g
+ dfs1 = zip eblock :
+ postorder_dfs_from_except blockenv eblock (unitUniqSet id)
+ dfs2 = postorder_dfs' g
+-- in ASSERT (map blockId dfs1 == map blockId dfs2) dfs2
+ in if (map blockId dfs1 == map blockId dfs2) then dfs2 else panic "inconsistent DFS"
+
+postorder_dfs_from
+ :: (HavingSuccessors b, LastNode l) => BlockEnv (Block m l) -> b -> [Block m l]
+postorder_dfs_from blocks b = postorder_dfs_from_except blocks b emptyBlockSet
+
+postorder_dfs_from_except :: forall b m l . (HavingSuccessors b, LastNode l) => BlockEnv (Block m l) -> b -> BlockSet -> [Block m l]
+postorder_dfs_from_except blocks b visited =
+ vchildren (get_children b) (\acc _visited -> acc) [] visited
+ where
+ -- vnode ::
+ -- Block m l -> ([Block m l] -> BlockSet -> a) -> [Block m l] -> BlockSet -> a
+ vnode block@(Block id _) cont acc visited =
+ if elemBlockSet id visited then
+ cont acc visited
+ else
+ let cont' acc visited = cont (block:acc) visited in
+ vchildren (get_children block) cont' acc (extendBlockSet visited id)
+ vchildren bs cont acc visited =
+ let next children acc visited =
+ case children of [] -> cont acc visited
+ (b:bs) -> vnode b (next bs) acc visited
+ in next bs acc visited
+ get_children block = foldl add_id [] (succs block)
+ add_id rst id = case lookupBlockEnv blocks id of
+ Just b -> b : rst
+ Nothing -> rst
+
-- | Slightly more complicated than the usual fold because we want to tell block
-- 'b1' what its inline successor is going to be, so that if 'b1' ends with
case gl of LastExit -> multi etail gh gblocks
_ -> panic "exit is not exit?!"
+prepare_for_splicing' ::
+ Graph m l -> (ZTail m l -> a) -> (ZTail m l -> ZHead m -> BlockEnv (Block m l) -> a)
+ -> a
+prepare_for_splicing' (Graph etail gblocks) single multi =
+ if isNullUFM gblocks then
+ case lastTail etail of
+ LastExit -> single etail
+ _ -> panic "bad single block"
+ else
+ case splitp_blocks is_exit gblocks of
+ Nothing -> panic "Can't find an exit block"
+ Just (gexit, gblocks) ->
+ let (gh, gl) = goto_end $ unzip gexit in
+ case gl of LastExit -> multi etail gh gblocks
+ _ -> panic "exit is not exit?!"
+
is_exit :: Block m l -> Bool
is_exit b = case last (unzip b) of { LastExit -> True; _ -> False }
splice_many_blocks entry exit others =
(LGraph eid (insertBlock (zipht head entry) others), exit)
+splice_head' head g =
+ ASSERT (single_exitg g) prepare_for_splicing' g splice_one_block splice_many_blocks
+ where splice_one_block tail' =
+ case ht_to_last head tail' of
+ (head, LastExit) -> (emptyBlockEnv, head)
+ _ -> panic "spliced LGraph without exit"
+ splice_many_blocks entry exit others =
+ (insertBlock (zipht head entry) others, exit)
+
+-- splice_tail :: Graph m l -> ZTail m l -> Graph m l
splice_tail g tail =
- ASSERT (single_exit g) prepare_for_splicing g splice_one_block splice_many_blocks
+ ASSERT (single_exitg g) prepare_for_splicing' g splice_one_block splice_many_blocks
+ where splice_one_block tail' = Graph (tail' `append_tails` tail) emptyBlockEnv
+ append_tails (ZLast LastExit) tail = tail
+ append_tails (ZLast _) _ = panic "spliced single block without LastExit"
+ append_tails (ZTail m t) tail = ZTail m (append_tails t tail)
+ splice_many_blocks entry exit others =
+ Graph entry (insertBlock (zipht exit tail) others)
+
+{-
+splice_tail g tail =
+ AS SERT (single_exit g) prepare_for_splicing g splice_one_block splice_many_blocks
where splice_one_block tail' = -- return tail' .. tail
case ht_to_last (ZFirst (lg_entry g)) tail' of
(head', LastExit) ->
_ -> panic "spliced single block without Exit"
splice_many_blocks entry exit others =
(entry, LGraph (lg_entry g) (insertBlock (zipht exit tail) others))
+-}
splice_head_only head g =
let FGraph eid gentry gblocks = entry g
ZBlock (ZFirst _) tail -> LGraph eid (insertBlock (zipht head tail) gblocks)
_ -> panic "entry not at start of block?!"
-remove_entry_label g =
- let FGraph e eblock others = entry g
- in case eblock of
- ZBlock (ZFirst id) tail
- | id == e -> Graph tail others
- _ -> panic "id doesn't match on entry block"
+splice_head_only' head (Graph tail gblocks) =
+ let eblock = zipht head tail in
+ LGraph (blockId eblock) (insertBlock eblock gblocks)
+
--- Translation
where pprBlock (Block id tail) = ppr id <> colon $$ ppr tail
blocks = postorder_dfs g
+pprGraph :: (Outputable m, Outputable l, LastNode l) => Graph m l -> SDoc
+pprGraph (Graph tail blockenv) =
+ text "{" $$ nest 2 (ppr tail $$ (vcat $ map pprBlock blocks)) $$ text "}"
+ where pprBlock (Block id tail) = ppr id <> colon $$ ppr tail
+ blocks = postorder_dfs_from blockenv tail
+
_unused :: FS.FastString
_unused = undefined
projects / ghc-hetmet.git / blobdiff