massive changes to add a 'zipper' representation of C--

Changes too numerous to comment on, but here is some old history that
I saved: 


Wed Aug 15 11:07:13 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * type synonyms made consistent with new Cmm types

    M ./compiler/nativeGen/MachInstrs.hs -2 +2

Mon Aug 20 19:22:14 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * pushing return info beyond cmm into codegen

    M ./compiler/codeGen/Bitmap.hs r3
    M ./compiler/codeGen/CgBindery.lhs r3
    M ./compiler/codeGen/CgCallConv.hs r3
    M ./compiler/codeGen/CgCase.lhs r3
    M ./compiler/codeGen/CgClosure.lhs r3
    M ./compiler/codeGen/CgCon.lhs r3
    M ./compiler/codeGen/CgExpr.lhs r3
    M ./compiler/codeGen/CgForeignCall.hs -6 +7 r3
    M ./compiler/codeGen/CgHeapery.lhs r3
    M ./compiler/codeGen/CgHpc.hs +1 r3
    M ./compiler/codeGen/CgInfoTbls.hs r3
    M ./compiler/codeGen/CgLetNoEscape.lhs r3
    M ./compiler/codeGen/CgMonad.lhs r3
    M ./compiler/codeGen/CgParallel.hs r3
    M ./compiler/codeGen/CgPrimOp.hs +3 r3
    M ./compiler/codeGen/CgProf.hs r3
    M ./compiler/codeGen/CgStackery.lhs r3
    M ./compiler/codeGen/CgTailCall.lhs r3
    M ./compiler/codeGen/CgTicky.hs r3
    M ./compiler/codeGen/CgUtils.hs -1 +1 r3
    M ./compiler/codeGen/ClosureInfo.lhs r3
    M ./compiler/codeGen/CodeGen.lhs r3
    M ./compiler/codeGen/SMRep.lhs r3
    M ./compiler/nativeGen/AsmCodeGen.lhs -2 +2 r1
    M ./compiler/nativeGen/MachCodeGen.hs -3 +3 r1
    M ./compiler/nativeGen/MachInstrs.hs r1
    M ./compiler/nativeGen/MachRegs.lhs r1
    M ./compiler/nativeGen/NCGMonad.hs r1
    M ./compiler/nativeGen/PositionIndependentCode.hs r1
    M ./compiler/nativeGen/PprMach.hs r1
    M ./compiler/nativeGen/RegAllocInfo.hs r1
    M ./compiler/nativeGen/RegisterAlloc.hs r1

Mon Aug 20 20:54:41 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * put CmmReturnInfo into a CmmCall (and related types)

    M ./compiler/cmm/Cmm.hs -2 +1 r3
    M ./compiler/cmm/CmmBrokenBlock.hs -13 +12 r1
    M ./compiler/cmm/CmmCPS.hs -3 +3
    M ./compiler/cmm/CmmCPSGen.hs -8 +6 r1
    M ./compiler/cmm/CmmLint.hs -1 +1
    M ./compiler/cmm/CmmLive.hs -1 +1
    M ./compiler/cmm/CmmOpt.hs -3 +3
    M ./compiler/cmm/CmmParse.y -6 +6 r3
    M ./compiler/cmm/PprC.hs -3 +3
    M ./compiler/cmm/PprCmm.hs -7 +4 r2
    M ./compiler/codeGen/CgForeignCall.hs -7 +6 r2
    M ./compiler/codeGen/CgHpc.hs -1 r1
    M ./compiler/codeGen/CgPrimOp.hs -3 r1
    M ./compiler/codeGen/CgUtils.hs -1 +1 r1
    M ./compiler/nativeGen/AsmCodeGen.lhs -2 +2
    M ./compiler/nativeGen/MachCodeGen.hs -3 +3 r1

Tue Aug 21 18:09:13 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * add call info in nativeGen

    M ./compiler/nativeGen/AsmCodeGen.lhs r1
    M ./compiler/nativeGen/MachInstrs.hs r1
    M ./compiler/nativeGen/MachRegs.lhs r1
    M ./compiler/nativeGen/NCGMonad.hs r1
    M ./compiler/nativeGen/PositionIndependentCode.hs r1
    M ./compiler/nativeGen/PprMach.hs r1
    M ./compiler/nativeGen/RegAllocInfo.hs r1

Wed Aug 22 16:41:58 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * ListGraph is now a newtype, not a synonym
  The resultant bookkeepping is unenviable, but the change
  greatly simplifies our ability to make Cmm things propertly
  Outputable for both list-graph and zipper-graph representations.

    M ./compiler/cmm/Cmm.hs -5 +3
    M ./compiler/cmm/CmmCPS.hs -2 +2
    M ./compiler/cmm/CmmCPSGen.hs -1 +1
    M ./compiler/cmm/CmmContFlowOpt.hs -3 +3
    M ./compiler/cmm/CmmCvt.hs -2 +2
    M ./compiler/cmm/CmmInfo.hs -2 +3
    M ./compiler/cmm/CmmLint.hs -1 +1
    M ./compiler/cmm/CmmOpt.hs -2 +2
    M ./compiler/cmm/PprC.hs -1 +1
    M ./compiler/cmm/PprCmm.hs -5 +8
    M ./compiler/cmm/PprCmmZ.hs -7 +1
    M ./compiler/codeGen/CgMonad.lhs -1 +1
    M ./compiler/nativeGen/AsmCodeGen.lhs -15 +15
    M ./compiler/nativeGen/MachCodeGen.hs -2 +2
    M ./compiler/nativeGen/PositionIndependentCode.hs -6 +6
    M ./compiler/nativeGen/PprMach.hs -3 +2
    M ./compiler/nativeGen/RegAllocColor.hs +1
    M ./compiler/nativeGen/RegAllocLinear.hs -4 +5
    M ./compiler/nativeGen/RegCoalesce.hs -6 +6
    M ./compiler/nativeGen/RegLiveness.hs -12 +12

Thu Aug 23 13:44:49 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * diagnostic assistance in case fromJust fails

    M ./compiler/nativeGen/MachCodeGen.hs -2 +5

Thu Aug 23 14:07:28 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * give every block, even the first, a label
    With branch-chain elimination, the first block of a procedure
    might be the target of a branch.  This actually happens to 
    a dozen or more procedures in the run-time system.

    M ./compiler/nativeGen/PprMach.hs -8 +3

Fri Aug 24 17:27:04 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * clean up the code in PprMach

    M ./compiler/nativeGen/PprMach.hs -16 +14

Fri Aug 24 19:35:03 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * a bunch of impedance matching to get the compiler to build, plus 
   * the plus is diagnostics for unreachable code, which required
     moving a lot of prettyprinting code

    M ./compiler/cmm/Cmm.hs -7 +5
    M ./compiler/cmm/CmmCPSZ.hs -1 +1
    M ./compiler/cmm/CmmCvt.hs -8 +8
    M ./compiler/cmm/CmmParse.y -4 +3
    M ./compiler/cmm/MkZipCfg.hs -19 +9
    M ./compiler/cmm/PprCmmZ.hs -118 +4
    M ./compiler/cmm/ZipCfg.hs -1 +13
    M ./compiler/cmm/ZipCfgCmm.hs -10 +129
    M ./compiler/main/HscMain.lhs -4 +4
    M ./compiler/nativeGen/NCGMonad.hs -2 +2
    M ./compiler/nativeGen/RegAllocInfo.hs -3 +3

Fri Aug 31 14:38:02 BST 2007  Norman Ramsey <nr@eecs.harvard.edu>
  * fix a warning about an import

    M ./compiler/nativeGen/RegAllocColor.hs -1 +1

4 files changed, 22 insertions, 7 deletions

diff --git a/compiler/codeGen/CgCon.lhs b/compiler/codeGen/CgCon.lhs
index 5269e4ec41..bf4cf3d9e7 100644
--- a/compiler/codeGen/CgCon.lhs
+++ b/compiler/codeGen/CgCon.lhs
@@ -397,6 +397,9 @@ cgTyCon tycon
 	    -- datatype closure table (for enumeration types)
 	    -- to (say) PrelBase_$wTrue_closure, which is defined in code_stuff
             -- Note that the closure pointers are tagged.
+
+            -- XXX comment says to put table after constructor decls, but
+            -- code appears to put it before --- NR 16 Aug 2007
 	; extra <- 
 	   if isEnumerationTyCon tycon then do
 	        tbl <- getCmm (emitRODataLits (mkLocalClosureTableLabel 
diff --git a/compiler/codeGen/CgMonad.lhs b/compiler/codeGen/CgMonad.lhs
index faa84c2174..7b2ee7dcab 100644
--- a/compiler/codeGen/CgMonad.lhs
+++ b/compiler/codeGen/CgMonad.lhs
@@ -80,9 +80,9 @@ import Id
 import VarEnv
 import OrdList
 import Unique
-import Util
+import Util()
 import UniqSupply
-import FastString
+import FastString()
 import Outputable
 
 import Control.Monad
@@ -241,6 +241,7 @@ flattenCgStmts id stmts =
 	    where (block,blocks) = flatten stmts
 	(CgFork fork_id stmts : ss) -> 
 	   flatten (CgFork fork_id stmts : CgStmt stmt : ss)
+        (CgStmt {} : _) -> panic "CgStmt not seen as ordinary"
 
   flatten (s:ss) = 
 	case s of
@@ -711,7 +712,8 @@ labelC :: BlockId -> Code
 labelC id = emitCgStmt (CgLabel id)
 
 newLabelC :: FCode BlockId
-newLabelC = do { id <- newUnique; return (BlockId id) }
+newLabelC = do { us <- newUniqSupply
+               ; return $ initUs_ us (freshBlockId "LabelC") }
 
 checkedAbsC :: CmmStmt -> Code
 -- Emit code, eliminating no-ops
@@ -758,6 +760,8 @@ emitSimpleProc lbl code
 
 getCmm :: Code -> FCode Cmm
 -- Get all the CmmTops (there should be no stmts)
+-- Return a single Cmm which may be split from other Cmms by
+-- object splitting (at a later stage)
 getCmm code 
   = do	{ state1 <- getState
 	; ((), state2) <- withState code (state1 { cgs_tops  = nilOL })
diff --git a/compiler/codeGen/CgTailCall.lhs b/compiler/codeGen/CgTailCall.lhs
index 16369ab573..cd100e8f21 100644
--- a/compiler/codeGen/CgTailCall.lhs
+++ b/compiler/codeGen/CgTailCall.lhs
@@ -34,7 +34,6 @@ import CgUtils
 import CgTicky
 import ClosureInfo
 import SMRep
-import MachOp
 import Cmm	
 import CmmUtils
 import CLabel
@@ -227,6 +226,7 @@ performTailCall fun_info arg_amodes pending_assts
         where
           --cond1 tag  = cmmULtWord tag lowCons
           -- More efficient than the above?
+{-
           tag_expr   = cmmGetClosureType (CmmReg nodeReg)
           cond1 tag  = cmmEqWord tag (CmmLit (mkIntCLit 0))
           cond2 tag  = cmmUGtWord tag highCons
@@ -234,11 +234,9 @@ performTailCall fun_info arg_amodes pending_assts
             -- CONSTR
           highCons   = CmmLit (mkIntCLit 8)
             -- CONSTR_NOCAF_STATIC (from ClosureType.h)
+-}
 
 
-untagCmmAssign (CmmAssign r cmmExpr) = CmmAssign r (cmmUntag cmmExpr)
-untagCmmAssign stmt                  = stmt
-
 directCall sp lbl args extra_args assts = do
   let
 	-- First chunk of args go in registers
@@ -475,3 +473,9 @@ adjustSpAndHp newRealSp
 	; setRealHp vHp
 	}
 \end{code}
+
+Some things are unused.
+\begin{code}
+_unused :: FS.FastString
+_unused = undefined
+\end{code}
diff --git a/compiler/codeGen/CodeGen.lhs b/compiler/codeGen/CodeGen.lhs
index ee25300277..a53ff49621 100644
--- a/compiler/codeGen/CodeGen.lhs
+++ b/compiler/codeGen/CodeGen.lhs
@@ -70,6 +70,10 @@ codeGen :: DynFlags
 	-> HpcInfo
 	-> IO [Cmm]		-- Output
 
+                -- N.B. returning '[Cmm]' and not 'Cmm' here makes it
+                -- possible for object splitting to split up the
+                -- pieces later.
+
 codeGen dflags this_mod data_tycons imported_mods 
 	cost_centre_info stg_binds hpc_info
   = do