X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FMkZipCfg.hs;h=d098bb620fe38684d6cd19ba8e4ac0ffef2cce2c;hb=cd437edc8792e5dbcfaa6a6b9948364e9d9d08f3;hp=385b41d5b9e7159b81e049a1fcfba3794052df52;hpb=0967b989b62abe69e0cd74ac563dbde200f7f3c5;p=ghc-hetmet.git

diff --git a/compiler/cmm/MkZipCfg.hs b/compiler/cmm/MkZipCfg.hs
index 385b41d..d098bb6 100644
--- a/compiler/cmm/MkZipCfg.hs
+++ b/compiler/cmm/MkZipCfg.hs
@@ -1,7 +1,7 @@
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# OPTIONS -Wall -fno-warn-name-shadowing #-}
 module MkZipCfg
-    ( AGraph, (<*>), emptyAGraph, withFreshLabel, withUnique
+    ( AGraph, (<*>), sequence
+    , emptyAGraph, withFreshLabel, withUnique
     , mkMiddle, mkMiddles, mkLast, mkZTail, mkBranch, mkLabel, mkIfThenElse, mkWhileDo
     , outOfLine
     , emptyGraph, graphOfMiddles, graphOfZTail
@@ -16,8 +16,9 @@ import Unique
 import UniqFM
 import UniqSupply
 
-import Prelude hiding (zip, unzip, last)
+import Prelude hiding (zip, unzip, last, sequence)
 
+#include "HsVersions.h"
 
 -------------------------------------------------------------------------
 --     GENERIC ZIPPER-BASED CONTROL-FLOW GRAPH (CONSTRUCTOR VIEW)      --
@@ -153,6 +154,8 @@ representation is agnostic on this point.)
 infixr 3 <*>
 (<*>) :: AGraph m l -> AGraph m l -> AGraph m l
 
+sequence :: [AGraph m l] -> AGraph m l
+
 -- | A graph is built up by splicing together graphs each containing a
 -- single node (where a label is considered a 'first' node.  The empty
 -- graph is a left and right unit for splicing.  All of the AGraph
@@ -198,6 +201,13 @@ mkBranch  :: (Outputable m, Outputable l, LastNode l) => BlockId   -> AGraph m l
 -- | For the structured control-flow constructs, a condition is
 -- represented as a function that takes as arguments the labels to
 -- goto on truth or falsehood.
+--
+--	mkIfThenElse mk_cond then else
+--	= (mk_cond L1 L2) <*> L1: then <*> goto J
+--		          <*> L2: else <*> goto J
+--	  <*> J:
+--
+-- where L1, L2, J are fresh
 
 mkIfThenElse :: (Outputable m, Outputable l, LastNode l)
                 => (BlockId -> BlockId -> AGraph m l) -- branch condition
@@ -240,6 +250,8 @@ newtype AGraph m l = AGraph (Graph m l -> UniqSM (Graph m l))
 AGraph f1 <*> AGraph f2 = AGraph f 
     where f g = f2 g >>= f1 -- note right associativity
 
+sequence = foldr (<*>) emptyAGraph
+
 emptyAGraph = AGraph return
 
 graphOfAGraph (AGraph f) = f emptyGraph
@@ -321,11 +333,12 @@ mkWhileDo cbranch body =
 note_this_code_becomes_unreachable ::
     (Monad m, LastNode l, Outputable middle, Outputable l) => ZTail middle l -> m ()
 
-note_this_code_becomes_unreachable = u
+note_this_code_becomes_unreachable = if debugIsOn then u else \_ -> return ()
     where u (ZLast LastExit)                       = return ()
           u (ZLast (LastOther l)) | isBranchNode l = return ()
                                     -- Note [Branch follows branch]
           u tail = fail ("unreachable code: " ++ showSDoc (ppr tail))
+
 {-
 Note [Branch follows branch]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -336,3 +349,15 @@ giving it a label, and start a new one that branches to that label.
 Emitting a Branch at this point is fine: 
        goto L1; L2: ...stuff... 
 -}
+
+
+-- | 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
+freshBlockId _ = do { u <- getUniqueUs; return $ BlockId u }
+
+_unused :: FS.FastString
+_unused = undefined