module CgMonad (
	Code,	-- type
	FCode,	-- type

	initC, thenC, thenFC, listCs, listFCs, mapCs, mapFCs,
	returnFC, fixC, fixC_, checkedAbsC, 
	stmtC, stmtsC, labelC, emitStmts, nopC, whenC, newLabelC,
	newUnique, newUniqSupply, 

	CgStmts, emitCgStmts, forkCgStmts, cgStmtsToBlocks,
	getCgStmts', getCgStmts,
	noCgStmts, oneCgStmt, consCgStmt,

	getCmm,
	emitData, emitProc, emitSimpleProc,

	forkLabelledCode,
	forkClosureBody, forkStatics, forkAlts, forkEval,
	forkEvalHelp, forkProc, codeOnly,
	SemiTaggingStuff, ConTagZ,

	EndOfBlockInfo(..),
	setEndOfBlockInfo, getEndOfBlockInfo,

	setSRT, getSRT,
	setSRTLabel, getSRTLabel, 
	setTickyCtrLabel, getTickyCtrLabel,

	StackUsage(..), HeapUsage(..),
	VirtualSpOffset, VirtualHpOffset,
	initStkUsage, initHpUsage,
	getHpUsage,  setHpUsage,
	heapHWM,

	getModuleName,

	Sequel(..), -- ToDo: unabstract?

	-- ideally we wouldn't export these, but some other modules access internal state
	getState, setState, getInfoDown, getDynFlags, getThisPackage, 

	-- more localised access to monad state	
	getStkUsage, setStkUsage,
	getBinds, setBinds, getStaticBinds,

	-- out of general friendliness, we also export ...
	CgInfoDownwards(..), CgState(..)	-- non-abstract
    ) where

#include "HsVersions.h"

import {-# SOURCE #-} CgBindery ( CgBindings, nukeVolatileBinds )

import DynFlags
import BlockId
import OldCmm
import OldCmmUtils
import CLabel
import StgSyn (SRT)
import SMRep
import Module
import Id
import VarEnv
import OrdList
import Unique
import UniqSupply
import Outputable

import Control.Monad
import Data.List

infixr 9 `thenC`	-- Right-associative!
infixr 9 `thenFC`

data CgInfoDownwards	-- information only passed *downwards* by the monad
  = MkCgInfoDown {
	cgd_dflags  :: DynFlags,
	cgd_mod     :: Module,		-- Module being compiled
	cgd_statics :: CgBindings,	-- [Id -> info] : static environment
	cgd_srt_lbl :: CLabel,		-- label of the current SRT
        cgd_srt     :: SRT,		-- the current SRT
	cgd_ticky   :: CLabel,		-- current destination for ticky counts
	cgd_eob     :: EndOfBlockInfo	-- Info for stuff to do at end of basic block:
  }

initCgInfoDown :: DynFlags -> Module -> CgInfoDownwards
initCgInfoDown dflags mod
  = MkCgInfoDown {	cgd_dflags  = dflags,
			cgd_mod     = mod,
			cgd_statics = emptyVarEnv,
			cgd_srt_lbl = error "initC: srt_lbl",
			cgd_srt     = error "initC: srt",
			cgd_ticky   = mkTopTickyCtrLabel,
			cgd_eob     = initEobInfo }

data CgState
  = MkCgState {
     cgs_stmts :: OrdList CgStmt,	  -- Current proc
     cgs_tops  :: OrdList CmmTop,
	-- Other procedures and data blocks in this compilation unit
	-- Both the latter two are ordered only so that we can 
	-- reduce forward references, when it's easy to do so
     
     cgs_binds :: CgBindings,	-- [Id -> info] : *local* bindings environment
     				-- Bindings for top-level things are given in
				-- the info-down part
     
     cgs_stk_usg :: StackUsage,
     cgs_hp_usg  :: HeapUsage,
     
     cgs_uniqs :: UniqSupply }

initCgState :: UniqSupply -> CgState
initCgState uniqs
  = MkCgState { cgs_stmts = nilOL, cgs_tops = nilOL,
		cgs_binds = emptyVarEnv, 
		cgs_stk_usg = initStkUsage, 
		cgs_hp_usg = initHpUsage,
		cgs_uniqs = uniqs }

data EndOfBlockInfo
  = EndOfBlockInfo
	VirtualSpOffset   -- Args Sp: trim the stack to this point at a
			  -- return; push arguments starting just
			  -- above this point on a tail call.
			  
			  -- This is therefore the stk ptr as seen
			  -- by a case alternative.
	Sequel

initEobInfo :: EndOfBlockInfo
initEobInfo = EndOfBlockInfo 0 OnStack

data Sequel
  = OnStack 		-- Continuation is on the stack

  | CaseAlts
	  CLabel     -- Jump to this; if the continuation is for a vectored
		     -- case this might be the label of a return vector
	  SemiTaggingStuff
	  Id	      -- The case binder, only used to see if it's dead

type SemiTaggingStuff
  = Maybe			-- Maybe[1] we don't have any semi-tagging stuff...
     ([(ConTagZ, CmmLit)],	-- Alternatives
      CmmLit)			-- Default (will be a can't happen RTS label if can't happen)

type ConTagZ = Int	-- A *zero-indexed* contructor tag

-- The case branch is executed only from a successful semitagging
-- venture, when a case has looked at a variable, found that it's
-- evaluated, and wants to load up the contents and go to the join
-- point.

type CgStmts = OrdList CgStmt

data CgStmt
  = CgStmt  CmmStmt
  | CgLabel BlockId
  | CgFork  BlockId CgStmts

flattenCgStmts :: BlockId -> CgStmts -> [CmmBasicBlock]
flattenCgStmts id stmts = 
	case flatten (fromOL stmts) of
	  ([],blocks)    -> blocks
	  (block,blocks) -> BasicBlock id block : blocks
 where
  flatten [] = ([],[])

  -- A label at the end of a function or fork: this label must not be reachable,
  -- but it might be referred to from another BB that also isn't reachable.
  -- Eliminating these has to be done with a dead-code analysis.  For now,
  -- we just make it into a well-formed block by adding a recursive jump.
  flatten [CgLabel id]
    = ( [CmmBranch id], [BasicBlock id [CmmBranch id]] )

  -- A jump/branch: throw away all the code up to the next label, because
  -- it is unreachable.  Be careful to keep forks that we find on the way.
  flatten (CgStmt stmt : stmts)
    | isJump stmt
    = case dropWhile isOrdinaryStmt stmts of
	[]                     -> ( [stmt], [] )
	[CgLabel id]	       -> ( [stmt], [BasicBlock id [CmmBranch id]])
	(CgLabel id : stmts)   -> ( [stmt], BasicBlock id block : blocks )
	    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
	  CgStmt stmt -> (stmt:block,blocks)
	  CgLabel id  -> ([CmmBranch id],BasicBlock id block:blocks)
	  CgFork fork_id stmts -> 
		(block, BasicBlock fork_id fork_block : fork_blocks ++ blocks)
		where (fork_block, fork_blocks) = flatten (fromOL stmts)
    where (block,blocks) = flatten ss

isJump :: CmmStmt -> Bool
isJump (CmmJump _ _) = True
isJump (CmmBranch _) = True
isJump (CmmSwitch _ _) = True
isJump (CmmReturn _) = True
isJump _ = False

isOrdinaryStmt :: CgStmt -> Bool
isOrdinaryStmt (CgStmt _) = True
isOrdinaryStmt _ = False

type VirtualHpOffset = WordOff	-- Both are in
type VirtualSpOffset = WordOff	-- units of words

data StackUsage 
  = StackUsage {
	virtSp :: VirtualSpOffset,
		-- Virtual offset of topmost allocated slot

	frameSp :: VirtualSpOffset,
		-- Virtual offset of the return address of the enclosing frame.
		-- This RA describes the liveness/pointedness of
		-- all the stack from frameSp downwards
		-- INVARIANT: less than or equal to virtSp

	 freeStk :: [VirtualSpOffset], 
		-- List of free slots, in *increasing* order
		-- INVARIANT: all <= virtSp
		-- All slots <= virtSp are taken except these ones

	 realSp :: VirtualSpOffset,	
		-- Virtual offset of real stack pointer register

	 hwSp :: VirtualSpOffset
  }		   -- Highest value ever taken by virtSp

-- INVARIANT: The environment contains no Stable references to
-- 	      stack slots below (lower offset) frameSp
--	      It can contain volatile references to this area though.

data HeapUsage =
  HeapUsage {
	virtHp :: VirtualHpOffset,	-- Virtual offset of highest-allocated word
	realHp :: VirtualHpOffset	-- realHp: Virtual offset of real heap ptr
  }

heapHWM :: HeapUsage -> VirtualHpOffset
heapHWM = virtHp

initStkUsage :: StackUsage
initStkUsage = StackUsage {
			virtSp = 0,
			frameSp = 0,
			freeStk = [],
			realSp = 0,
			hwSp = 0
	       }
		
initHpUsage :: HeapUsage 
initHpUsage = HeapUsage {
	      	virtHp = 0,
		realHp = 0
	      }

stateIncUsage :: CgState -> CgState -> CgState
stateIncUsage s1 s2@(MkCgState { cgs_stk_usg = stk_usg, cgs_hp_usg = hp_usg })
     = s1 { cgs_hp_usg  = cgs_hp_usg  s1 `maxHpHw`  virtHp hp_usg,
	    cgs_stk_usg = cgs_stk_usg s1 `maxStkHw` hwSp   stk_usg }
       `addCodeBlocksFrom` s2
		
stateIncUsageEval :: CgState -> CgState -> CgState
stateIncUsageEval s1 s2
     = s1 { cgs_stk_usg = cgs_stk_usg s1 `maxStkHw` hwSp (cgs_stk_usg s2) }
       `addCodeBlocksFrom` s2
	-- We don't max the heap high-watermark because stateIncUsageEval is
	-- used only in forkEval, which in turn is only used for blocks of code
	-- which do their own heap-check.

addCodeBlocksFrom :: CgState -> CgState -> CgState
-- Add code blocks from the latter to the former
-- (The cgs_stmts will often be empty, but not always; see codeOnly)
s1 `addCodeBlocksFrom` s2
  = s1 { cgs_stmts = cgs_stmts s1 `appOL` cgs_stmts s2,
	 cgs_tops  = cgs_tops  s1 `appOL` cgs_tops  s2 }

maxHpHw :: HeapUsage -> VirtualHpOffset -> HeapUsage
hp_usg `maxHpHw` hw = hp_usg { virtHp = virtHp hp_usg `max` hw }

maxStkHw :: StackUsage -> VirtualSpOffset -> StackUsage
stk_usg `maxStkHw` hw = stk_usg { hwSp = hwSp stk_usg `max` hw }

newtype FCode a = FCode (CgInfoDownwards -> CgState -> (a, CgState))
type Code       = FCode ()

instance Monad FCode where
	(>>=) = thenFC
	return = returnFC

{-# INLINE thenC #-}
{-# INLINE thenFC #-}
{-# INLINE returnFC #-}

initC :: DynFlags -> Module -> FCode a -> IO a

initC dflags mod (FCode code)
  = do	{ uniqs <- mkSplitUniqSupply 'c'
	; case code (initCgInfoDown dflags mod) (initCgState uniqs) of
	      (res, _) -> return res
	}

returnFC :: a -> FCode a
returnFC val = FCode (\_ state -> (val, state))

thenC :: Code -> FCode a -> FCode a
thenC (FCode m) (FCode k) = 
  	FCode (\info_down state -> let (_,new_state) = m info_down state in 
  		k info_down new_state)

listCs :: [Code] -> Code
listCs [] = return ()
listCs (fc:fcs) = do
	fc
	listCs fcs
   	
mapCs :: (a -> Code) -> [a] -> Code
mapCs = mapM_

thenFC	:: FCode a -> (a -> FCode c) -> FCode c
thenFC (FCode m) k = FCode (
	\info_down state ->
		let 
			(m_result, new_state) = m info_down state
			(FCode kcode) = k m_result
		in 
			kcode info_down new_state
	)

listFCs :: [FCode a] -> FCode [a]
listFCs = sequence

mapFCs :: (a -> FCode b) -> [a] -> FCode [b]
mapFCs = mapM

fixC :: (a -> FCode a) -> FCode a
fixC fcode = FCode (
	\info_down state -> 
		let
			FCode fc = fcode v
			result@(v,_) = fc info_down state
			--	    ^--------^
		in
			result
	)

fixC_ :: (a -> FCode a) -> FCode ()
fixC_ fcode = fixC fcode >> return ()

getState :: FCode CgState
getState = FCode $ \_ state -> (state,state)

setState :: CgState -> FCode ()
setState state = FCode $ \_ _ -> ((),state)

getStkUsage :: FCode StackUsage
getStkUsage = do
	state <- getState
	return $ cgs_stk_usg state

setStkUsage :: StackUsage -> Code
setStkUsage new_stk_usg = do
	state <- getState
	setState $ state {cgs_stk_usg = new_stk_usg}

getHpUsage :: FCode HeapUsage
getHpUsage = do
	state <- getState
	return $ cgs_hp_usg state
	
setHpUsage :: HeapUsage -> Code
setHpUsage new_hp_usg = do
	state <- getState
	setState $ state {cgs_hp_usg = new_hp_usg}

getBinds :: FCode CgBindings
getBinds = do
	state <- getState
	return $ cgs_binds state
	
setBinds :: CgBindings -> FCode ()
setBinds new_binds = do
	state <- getState
	setState $ state {cgs_binds = new_binds}

getStaticBinds :: FCode CgBindings
getStaticBinds = do
	info  <- getInfoDown
	return (cgd_statics info)

withState :: FCode a -> CgState -> FCode (a,CgState)
withState (FCode fcode) newstate = FCode $ \info_down state -> 
	let (retval, state2) = fcode info_down newstate in ((retval,state2), state)

newUniqSupply :: FCode UniqSupply
newUniqSupply = do
	state <- getState
	let (us1, us2) = splitUniqSupply (cgs_uniqs state)
	setState $ state { cgs_uniqs = us1 }
	return us2

newUnique :: FCode Unique
newUnique = do
	us <- newUniqSupply
	return (uniqFromSupply us)

------------------
getInfoDown :: FCode CgInfoDownwards
getInfoDown = FCode $ \info_down state -> (info_down,state)

getDynFlags :: FCode DynFlags
getDynFlags = liftM cgd_dflags getInfoDown

getThisPackage :: FCode PackageId
getThisPackage = liftM thisPackage getDynFlags

withInfoDown :: FCode a -> CgInfoDownwards -> FCode a
withInfoDown (FCode fcode) info_down = FCode $ \_ state -> fcode info_down state 

doFCode :: FCode a -> CgInfoDownwards -> CgState -> (a,CgState)
doFCode (FCode fcode) info_down state = fcode info_down state

forkClosureBody :: Code -> Code
forkClosureBody body_code
  = do	{ info <- getInfoDown
	; us   <- newUniqSupply
	; state <- getState
   	; let	body_info_down = info { cgd_eob = initEobInfo }
		((),fork_state)	= doFCode body_code body_info_down 
					  (initCgState us)
	; ASSERT( isNilOL (cgs_stmts fork_state) )
	  setState $ state `addCodeBlocksFrom` fork_state }
	
forkStatics :: FCode a -> FCode a
forkStatics body_code
  = do	{ info  <- getInfoDown
	; us    <- newUniqSupply
	; state <- getState
	; let	rhs_info_down = info { cgd_statics = cgs_binds state,
				       cgd_eob     = initEobInfo }
		(result, fork_state_out) = doFCode body_code rhs_info_down 
						   (initCgState us)
	; ASSERT( isNilOL (cgs_stmts fork_state_out) )
	  setState (state `addCodeBlocksFrom` fork_state_out)
	; return result }

forkProc :: Code -> FCode CgStmts
forkProc body_code
  = do	{ info_down <- getInfoDown
	; us    <- newUniqSupply
	; state <- getState
	; let	fork_state_in = (initCgState us) 
					{ cgs_binds   = cgs_binds state,
					  cgs_stk_usg = cgs_stk_usg state,
					  cgs_hp_usg  = cgs_hp_usg state }
			-- ToDo: is the hp usage necesary?
		(code_blks, fork_state_out) = doFCode (getCgStmts body_code) 
						      info_down fork_state_in
	; setState $ state `stateIncUsageEval` fork_state_out
	; return code_blks }

codeOnly :: Code -> Code
-- Emit any code from the inner thing into the outer thing
-- Do not affect anything else in the outer state
-- Used in almost-circular code to prevent false loop dependencies
codeOnly body_code
  = do	{ info_down <- getInfoDown
	; us   <- newUniqSupply
	; state <- getState
	; let	fork_state_in = (initCgState us) { cgs_binds   = cgs_binds state,
					           cgs_stk_usg = cgs_stk_usg state,
					           cgs_hp_usg  = cgs_hp_usg state }
		((), fork_state_out) = doFCode body_code info_down fork_state_in
	; setState $ state `addCodeBlocksFrom` fork_state_out }

forkAlts :: [FCode a] -> FCode [a]

forkAlts branch_fcodes
  = do	{ info_down <- getInfoDown
	; us <- newUniqSupply
	; state <- getState
	; let compile us branch 
		= (us2, doFCode branch info_down branch_state)
		where
		  (us1,us2) = splitUniqSupply us
	          branch_state = (initCgState us1) {
					cgs_binds   = cgs_binds state,
					cgs_stk_usg = cgs_stk_usg state,
					cgs_hp_usg  = cgs_hp_usg state }

	      (_us, results) = mapAccumL compile us branch_fcodes
	      (branch_results, branch_out_states) = unzip results
	; setState $ foldl stateIncUsage state branch_out_states
		-- NB foldl.  state is the *left* argument to stateIncUsage
	; return branch_results }

forkEval :: EndOfBlockInfo              -- For the body
    	 -> Code			-- Code to set environment
	 -> FCode Sequel		-- Semi-tagging info to store
	 -> FCode EndOfBlockInfo	-- The new end of block info

forkEval body_eob_info env_code body_code
  = do  { (v, sequel) <- forkEvalHelp body_eob_info env_code body_code
 	; returnFC (EndOfBlockInfo v sequel) }

forkEvalHelp :: EndOfBlockInfo  -- For the body
    	     -> Code		-- Code to set environment
	     -> FCode a		-- The code to do after the eval
	     -> FCode (VirtualSpOffset,	-- Sp
		       a)		-- Result of the FCode
	-- A disturbingly complicated function
forkEvalHelp body_eob_info env_code body_code
  = do	{ info_down <- getInfoDown
	; us   <- newUniqSupply
	; state <- getState
	; let { info_down_for_body = info_down {cgd_eob = body_eob_info}
	      ; (_, env_state) = doFCode env_code info_down_for_body 
					 (state {cgs_uniqs = us})
	      ; state_for_body = (initCgState (cgs_uniqs env_state)) 
					{ cgs_binds   = binds_for_body,
	      				  cgs_stk_usg = stk_usg_for_body }
	      ; binds_for_body   = nukeVolatileBinds (cgs_binds env_state)
	      ; stk_usg_from_env = cgs_stk_usg env_state
	      ; virtSp_from_env  = virtSp stk_usg_from_env
	      ; stk_usg_for_body = stk_usg_from_env {realSp = virtSp_from_env,
	      					     hwSp   = virtSp_from_env}
	      ; (value_returned, state_at_end_return)
	        	= doFCode body_code info_down_for_body state_for_body		
	  } 
	; ASSERT( isNilOL (cgs_stmts state_at_end_return) )
		 -- The code coming back should consist only of nested declarations,
		 -- notably of the return vector!
	  setState $ state `stateIncUsageEval` state_at_end_return
	; return (virtSp_from_env, value_returned) }


-- ----------------------------------------------------------------------------
-- Combinators for emitting code

nopC :: Code
nopC = return ()

whenC :: Bool -> Code -> Code
whenC True  code = code
whenC False _    = nopC

-- Corresponds to 'emit' in new code generator with a smart constructor
-- from cmm/MkGraph.hs
stmtC :: CmmStmt -> Code
stmtC stmt = emitCgStmt (CgStmt stmt)

labelC :: BlockId -> Code
labelC id = emitCgStmt (CgLabel id)

newLabelC :: FCode BlockId
newLabelC = do { u <- newUnique
               ; return $ mkBlockId u }

checkedAbsC :: CmmStmt -> Code
-- Emit code, eliminating no-ops
checkedAbsC stmt = emitStmts (if isNopStmt stmt then nilOL
	 		      else unitOL stmt)

stmtsC :: [CmmStmt] -> Code
stmtsC stmts = emitStmts (toOL stmts)

-- Emit code; no no-op checking
emitStmts :: CmmStmts -> Code
emitStmts stmts = emitCgStmts (fmap CgStmt stmts)

-- forkLabelledCode is for emitting a chunk of code with a label, outside
-- of the current instruction stream.
forkLabelledCode :: Code -> FCode BlockId
forkLabelledCode code = getCgStmts code >>= forkCgStmts

emitCgStmt :: CgStmt -> Code
emitCgStmt stmt
  = do	{ state <- getState
	; setState $ state { cgs_stmts = cgs_stmts state `snocOL` stmt }
	}

emitData :: Section -> CmmStatics -> Code
emitData sect lits
  = do 	{ state <- getState
	; setState $ state { cgs_tops = cgs_tops state `snocOL` data_block } }
  where
    data_block = CmmData sect lits

emitProc :: CmmInfo -> CLabel -> [CmmFormal] -> [CmmBasicBlock] -> Code
emitProc info lbl [] blocks
  = do  { let proc_block = CmmProc info lbl (ListGraph blocks)
	; state <- getState
	; setState $ state { cgs_tops = cgs_tops state `snocOL` proc_block } }
emitProc _ _ (_:_) _ = panic "emitProc called with nonempty args"

emitSimpleProc :: CLabel -> Code -> Code
-- Emit a procedure whose body is the specified code; no info table
emitSimpleProc lbl code
  = do	{ stmts <- getCgStmts code
	; blks <- cgStmtsToBlocks stmts
	; emitProc (CmmInfo Nothing Nothing CmmNonInfoTable) lbl [] blks }

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 })
	; setState $ state2 { cgs_tops = cgs_tops state1 } 
	; return (Cmm (fromOL (cgs_tops state2))) 
        }

-- ----------------------------------------------------------------------------
-- CgStmts

-- These functions deal in terms of CgStmts, which is an abstract type
-- representing the code in the current proc.


-- emit CgStmts into the current instruction stream
emitCgStmts :: CgStmts -> Code
emitCgStmts stmts
  = do	{ state <- getState
	; setState $ state { cgs_stmts = cgs_stmts state `appOL` stmts } }

-- emit CgStmts outside the current instruction stream, and return a label
forkCgStmts :: CgStmts -> FCode BlockId
forkCgStmts stmts
  = do  { id <- newLabelC
	; emitCgStmt (CgFork id stmts)
	; return id
	}

-- turn CgStmts into [CmmBasicBlock], for making a new proc.
cgStmtsToBlocks :: CgStmts -> FCode [CmmBasicBlock]
cgStmtsToBlocks stmts
  = do  { id <- newLabelC
	; return (flattenCgStmts id stmts)
	}	

-- collect the code emitted by an FCode computation
getCgStmts' :: FCode a -> FCode (a, CgStmts)
getCgStmts' fcode
  = do	{ state1 <- getState
	; (a, state2) <- withState fcode (state1 { cgs_stmts = nilOL })
	; setState $ state2 { cgs_stmts = cgs_stmts state1  }
	; return (a, cgs_stmts state2) }

getCgStmts :: FCode a -> FCode CgStmts
getCgStmts fcode = do { (_,stmts) <- getCgStmts' fcode; return stmts }

-- Simple ways to construct CgStmts:
noCgStmts :: CgStmts
noCgStmts = nilOL

oneCgStmt :: CmmStmt -> CgStmts
oneCgStmt stmt = unitOL (CgStmt stmt)

consCgStmt :: CmmStmt -> CgStmts -> CgStmts
consCgStmt stmt stmts = CgStmt stmt `consOL` stmts

-- ----------------------------------------------------------------------------
-- Get the current module name

getModuleName :: FCode Module
getModuleName = do { info <- getInfoDown; return (cgd_mod info) }

-- ----------------------------------------------------------------------------
-- Get/set the end-of-block info

setEndOfBlockInfo :: EndOfBlockInfo -> Code -> Code
setEndOfBlockInfo eob_info code	= do
	info  <- getInfoDown
	withInfoDown code (info {cgd_eob = eob_info})

getEndOfBlockInfo :: FCode EndOfBlockInfo
getEndOfBlockInfo = do
	info <- getInfoDown
	return (cgd_eob info)

-- ----------------------------------------------------------------------------
-- Get/set the current SRT label

-- There is just one SRT for each top level binding; all the nested
-- bindings use sub-sections of this SRT.  The label is passed down to
-- the nested bindings via the monad.

getSRTLabel :: FCode CLabel	-- Used only by cgPanic
getSRTLabel = do info  <- getInfoDown
		 return (cgd_srt_lbl info)

setSRTLabel :: CLabel -> FCode a -> FCode a
setSRTLabel srt_lbl code
  = do  info <- getInfoDown
	withInfoDown code (info { cgd_srt_lbl = srt_lbl})

getSRT :: FCode SRT
getSRT = do info <- getInfoDown
            return (cgd_srt info)

setSRT :: SRT -> FCode a -> FCode a
setSRT srt code
  = do info <- getInfoDown
       withInfoDown code (info { cgd_srt = srt})

-- ----------------------------------------------------------------------------
-- Get/set the current ticky counter label

getTickyCtrLabel :: FCode CLabel
getTickyCtrLabel = do
	info <- getInfoDown
	return (cgd_ticky info)

setTickyCtrLabel :: CLabel -> Code -> Code
setTickyCtrLabel ticky code = do
	info <- getInfoDown
	withInfoDown code (info {cgd_ticky = ticky})