Add cmm-notes, describing Simon and John's work on Cmm pipeline

[ghc-hetmet.git] / compiler / cmm / CmmProcPointZ.hs

diff --git a/compiler/cmm/CmmProcPointZ.hs b/compiler/cmm/CmmProcPointZ.hs
index 5ec65c5..13f6421 100644 (file)
--- a/compiler/cmm/CmmProcPointZ.hs
+++ b/compiler/cmm/CmmProcPointZ.hs
@@ -5,26 +5,23 @@ module CmmProcPointZ
     )
 where
 
-import qualified Prelude as P
 import Prelude hiding (zip, unzip, last)
 
 import BlockId
 import CLabel
 import Cmm hiding (blockId)
 import CmmContFlowOpt
-import CmmExpr
 import CmmInfo
 import CmmLiveZ
 import CmmTx
 import DFMonad
 import FiniteMap
-import List (sortBy)
+import Data.List (sortBy)
 import Maybes
 import MkZipCfg
 import MkZipCfgCmm hiding (CmmBlock, CmmGraph, CmmTopZ)
-import Monad
+import Control.Monad
 import Outputable
-import Panic
 import UniqSet
 import UniqSupply
 import ZipCfg
@@ -130,18 +127,21 @@ forward = ForwardTransfers first middle last exit
 -- those that are induced by calls in the original graph
 -- and those that are introduced because they're reachable from multiple proc points.
 callProcPoints      :: CmmGraph -> ProcPointSet
-minimalProcPointSet :: ProcPointSet -> CmmGraph -> FuelMonad ProcPointSet
-
 callProcPoints g = fold_blocks add (unitBlockSet (lg_entry g)) g
   where add b set = case last $ unzip b of
                       LastOther (LastCall _ (Just k) _ _ _) -> extendBlockSet set k
                       _ -> set
 
+minimalProcPointSet :: ProcPointSet -> CmmGraph -> FuelMonad ProcPointSet
+-- Given the set of successors of calls (which must be proc-points)
+-- figure ou the minimal set of necessary proc-points
 minimalProcPointSet callProcPoints g = extendPPSet g (postorder_dfs g) callProcPoints
 
 type PPFix = FuelMonad (ForwardFixedPoint Middle Last Status ())
 
 procPointAnalysis :: ProcPointSet -> CmmGraph -> FuelMonad (BlockEnv Status)
+-- Once you know what the proc-points are, figure out
+-- what proc-points each block is reachable from
 procPointAnalysis procPoints g =
   let addPP env id = extendBlockEnv env id ProcPoint
       initProcPoints = foldl addPP emptyBlockEnv (blockSetToList procPoints)
@@ -329,7 +329,7 @@ add_CopyIns callPPs protos blocks =
            = case lookupBlockEnv protos id of
                Just (Protocol c fs _area) ->
                  do LGraph _ blocks <-
-                      lgraphOfAGraph (mkLabel id <*> copyInSlot c False fs <*> mkZTail t)
+                      lgraphOfAGraph (mkLabel id <*> copyInSlot c fs <*> mkZTail t)
                     return (map snd $ blockEnvToList blocks)
                Nothing -> return [b]
            | otherwise = return [b]
@@ -356,8 +356,7 @@ add_CopyOuts protos procPoints g = fold_blocks mb_copy_out (return emptyBlockEnv
                     if elemBlockSet succId procPoints then
                       case lookupBlockEnv protos succId of
                         Nothing -> z
-                        Just (Protocol c fs _area) ->
-                          insert z succId $ copyOutSlot c Jump fs
+                        Just (Protocol c fs _area) -> insert z succId $ copyOutSlot c fs
                     else z
                   insert z succId m =
                     do (b, bmap) <- z
@@ -454,13 +453,20 @@ splitAtProcPoints entry_label callPPs procPoints procMap
      graphEnv <- foldM add_jumps emptyBlockEnv $ blockEnvToList graphEnv
      let to_proc (bid, g) | elemBlockSet bid callPPs =
            if bid == entry then 
-             CmmProc (CmmInfo gc upd_fr info_tbl) top_l top_args g
+             CmmProc (CmmInfo gc upd_fr info_tbl) top_l top_args (replacePPIds g)
            else
-             CmmProc emptyContInfoTable lbl [] g
+             CmmProc emptyContInfoTable lbl [] (replacePPIds g)
            where lbl = expectJust "pp label" $ lookupFM procLabels bid
          to_proc (bid, g) =
-           CmmProc (CmmInfo Nothing Nothing CmmNonInfoTable) lbl [] g
+           CmmProc (CmmInfo Nothing Nothing CmmNonInfoTable) lbl [] (replacePPIds g)
              where lbl = expectJust "pp label" $ lookupFM procLabels bid
+         -- References to procpoint IDs can now be replaced with the infotable's label
+         replacePPIds (x, g) = (x, map_nodes id (mapExpMiddle repl) (mapExpLast repl) g)
+           where repl e@(CmmLit (CmmBlock bid)) =
+                   case lookupFM procLabels bid of
+                     Just l  -> CmmLit (CmmLabel (entryLblToInfoLbl l))
+                     Nothing -> e
+                 repl e = e
      -- The C back end expects to see return continuations before the call sites.
      -- Here, we sort them in reverse order -- it gets reversed later.
      let (_, block_order) = foldl add_block_num (0::Int, emptyBlockEnv) (postorder_dfs g)