-----------------------------------------------------------------------------
--
-- Code generation for profiling
--
-- (c) The University of Glasgow 2004-2006
--
-----------------------------------------------------------------------------

module StgCmmProf (
	initCostCentres, ccType, ccsType,
	mkCCostCentre, mkCCostCentreStack,

	-- Cost-centre Profiling
	dynProfHdr, profDynAlloc, profAlloc, staticProfHdr, initUpdFrameProf,
	enterCostCentre, enterCostCentrePAP, enterCostCentreThunk, 
	chooseDynCostCentres, 
	costCentreFrom, 
	curCCS, curCCSAddr,
	emitSetCCC, emitCCS,

	saveCurrentCostCentre, restoreCurrentCostCentre,

	-- Lag/drag/void stuff
	ldvEnter, ldvEnterClosure, ldvRecordCreate
  ) where

#include "HsVersions.h"
#include "../includes/MachDeps.h"
 -- For WORD_SIZE_IN_BITS only.
#include "../includes/rts/Constants.h"
	-- For LDV_CREATE_MASK, LDV_STATE_USE
	-- which are StgWords
#include "../includes/DerivedConstants.h"
	-- For REP_xxx constants, which are MachReps

import StgCmmClosure
import StgCmmUtils
import StgCmmMonad
import SMRep

import MkGraph
import CmmExpr
import CmmDecl
import CmmUtils
import CLabel

import Id
import qualified Module
import CostCentre
import StgSyn
import StaticFlags
import FastString
import Module
import Constants	-- Lots of field offsets
import Outputable

import Data.Char
import Control.Monad

-----------------------------------------------------------------------------
--
-- Cost-centre-stack Profiling
--
-----------------------------------------------------------------------------

-- Expression representing the current cost centre stack
ccsType :: CmmType 	-- Type of a cost-centre stack
ccsType = bWord

ccType :: CmmType 	-- Type of a cost centre
ccType = bWord

curCCS :: CmmExpr
curCCS = CmmLoad curCCSAddr ccsType

-- Address of current CCS variable, for storing into
curCCSAddr :: CmmExpr
curCCSAddr = CmmLit (CmmLabel (mkCmmDataLabel rtsPackageId (fsLit "CCCS")))

mkCCostCentre :: CostCentre -> CmmLit
mkCCostCentre cc = CmmLabel (mkCCLabel cc)

mkCCostCentreStack :: CostCentreStack -> CmmLit
mkCCostCentreStack ccs = CmmLabel (mkCCSLabel ccs)

costCentreFrom :: CmmExpr 	-- A closure pointer
	       -> CmmExpr	-- The cost centre from that closure
costCentreFrom cl = CmmLoad (cmmOffsetB cl oFFSET_StgHeader_ccs) ccsType

staticProfHdr :: CostCentreStack -> [CmmLit]
-- The profiling header words in a static closure
-- Was SET_STATIC_PROF_HDR
staticProfHdr ccs = ifProfilingL [mkCCostCentreStack ccs, 
			  	  staticLdvInit]

dynProfHdr :: CmmExpr -> [CmmExpr]
-- Profiling header words in a dynamic closure
dynProfHdr ccs = ifProfilingL [ccs, dynLdvInit]

initUpdFrameProf :: CmmExpr -> FCode ()
-- Initialise the profiling field of an update frame
initUpdFrameProf frame_amode 
  = ifProfiling $	-- frame->header.prof.ccs = CCCS
    emit (mkStore (cmmOffsetB frame_amode oFFSET_StgHeader_ccs) curCCS)
	-- frame->header.prof.hp.rs = NULL (or frame-header.prof.hp.ldvw = 0) 
	-- is unnecessary because it is not used anyhow.

---------------------------------------------------------------------------
-- 	Saving and restoring the current cost centre
---------------------------------------------------------------------------

{-	Note [Saving the current cost centre]
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The current cost centre is like a global register.  Like other 
global registers, it's a caller-saves one.  But consider
	case (f x) of (p,q) -> rhs
Since 'f' may set the cost centre, we must restore it 
before resuming rhs.  So we want code like this:
	local_cc = CCC  -- save
	r = f( x )
	CCC = local_cc  -- restore
That is, we explicitly "save" the current cost centre in
a LocalReg, local_cc; and restore it after the call. The
C-- infrastructure will arrange to save local_cc across the
call. 

The same goes for join points;
	let j x = join-stuff
	in blah-blah
We want this kind of code:
	local_cc = CCC  -- save
	blah-blah
     J: 
        CCC = local_cc  -- restore
-}

saveCurrentCostCentre :: FCode (Maybe LocalReg)
	-- Returns Nothing if profiling is off
saveCurrentCostCentre
  | not opt_SccProfilingOn 
  = return Nothing
  | otherwise
  = do	{ local_cc <- newTemp ccType
	; emit (mkAssign (CmmLocal local_cc) curCCS)
	; return (Just local_cc) }

restoreCurrentCostCentre :: Maybe LocalReg -> FCode ()
restoreCurrentCostCentre Nothing 
  = return ()
restoreCurrentCostCentre (Just local_cc)
  = emit (mkStore curCCSAddr (CmmReg (CmmLocal local_cc)))


-------------------------------------------------------------------------------
-- Recording allocation in a cost centre
-------------------------------------------------------------------------------

-- | Record the allocation of a closure.  The CmmExpr is the cost
-- centre stack to which to attribute the allocation.
profDynAlloc :: ClosureInfo -> CmmExpr -> FCode ()
profDynAlloc cl_info ccs
  = ifProfiling $
    profAlloc (CmmLit (mkIntCLit (closureSize cl_info))) ccs

-- | Record the allocation of a closure (size is given by a CmmExpr)
-- The size must be in words, because the allocation counter in a CCS counts
-- in words.
profAlloc :: CmmExpr -> CmmExpr -> FCode ()
profAlloc words ccs
  = ifProfiling $
    emit (addToMemE alloc_rep
		(cmmOffsetB ccs oFFSET_CostCentreStack_mem_alloc)
	  	(CmmMachOp (MO_UU_Conv wordWidth (typeWidth alloc_rep)) $
		  [CmmMachOp mo_wordSub [words, 
					 CmmLit (mkIntCLit profHdrSize)]]))
		-- subtract the "profiling overhead", which is the
		-- profiling header in a closure.
 where 
	alloc_rep =  REP_CostCentreStack_mem_alloc

-- ----------------------------------------------------------------------
-- Setting the cost centre in a new closure

chooseDynCostCentres :: CostCentreStack
		     -> [Id] 	        -- Args
		     -> StgExpr		-- Body
		     -> FCode (CmmExpr, CmmExpr)
-- Called when allocating a closure
-- Tells which cost centre to put in the object, and which
-- to blame the cost of allocation on
chooseDynCostCentres ccs args body = do
  -- Cost-centre we record in the object
  use_ccs <- emitCCS ccs

  -- Cost-centre on whom we blame the allocation
  let blame_ccs
	| null args && isBox body = CmmLit (mkCCostCentreStack overheadCCS)
	| otherwise		  = use_ccs

  return (use_ccs, blame_ccs)


-- Some CostCentreStacks are a sequence of pushes on top of CCCS.
-- These pushes must be performed before we can refer to the stack in
-- an expression.
emitCCS :: CostCentreStack -> FCode CmmExpr
emitCCS ccs = push_em (ccsExpr ccs') (reverse cc's)
  where
	(cc's, ccs') = decomposeCCS ccs

	push_em ccs [] = return ccs
	push_em ccs (cc:rest) = do
  	  tmp <- newTemp ccsType	
	  pushCostCentre tmp ccs cc
	  push_em (CmmReg (CmmLocal tmp)) rest

ccsExpr :: CostCentreStack -> CmmExpr
ccsExpr ccs
  | isCurrentCCS ccs = curCCS
  | otherwise        = CmmLit (mkCCostCentreStack ccs)


isBox :: StgExpr -> Bool
-- If it's an utterly trivial RHS, then it must be
-- one introduced by boxHigherOrderArgs for profiling,
-- so we charge it to "OVERHEAD".
-- This looks like a GROSS HACK to me --SDM
isBox (StgApp _ []) = True
isBox _             = False


-- -----------------------------------------------------------------------
-- Setting the current cost centre on entry to a closure

-- For lexically scoped profiling we have to load the cost centre from
-- the closure entered, if the costs are not supposed to be inherited.
-- This is done immediately on entering the fast entry point.

-- Load current cost centre from closure, if not inherited.
-- Node is guaranteed to point to it, if profiling and not inherited.

enterCostCentre
   :: ClosureInfo 
   -> CostCentreStack
   -> StgExpr	-- The RHS of the closure
   -> FCode ()

-- We used to have a special case for bindings of form
--	f = g True
-- where g has arity 2.  The RHS is a thunk, but we don't
-- need to update it; and we want to subsume costs.
-- We don't have these sort of PAPs any more, so the special
-- case has gone away.

enterCostCentre closure_info ccs body
  = ifProfiling $
    ASSERT2(not (noCCSAttached ccs), ppr (closureName closure_info) <+> ppr ccs)
    enter_cost_centre closure_info ccs body

enter_cost_centre :: ClosureInfo -> CostCentreStack -> StgExpr -> FCode ()
enter_cost_centre closure_info ccs body
  | isSubsumedCCS ccs
  = ASSERT(isToplevClosure closure_info)
    ASSERT(re_entrant)
    enter_ccs_fsub
	
  | isDerivedFromCurrentCCS ccs
  = do {
	if re_entrant && not is_box
    	  then
		enter_ccs_fun node_ccs
    	  else
	  	emit (mkStore curCCSAddr node_ccs)

	-- don't forget to bump the scc count.  This closure might have been
	-- of the form   let x = _scc_ "x" e in ...x..., which the SCCfinal
	-- pass has turned into simply  let x = e in ...x... and attached
	-- the _scc_ as PushCostCentre(x,CCCS) on the x closure.  So that
	-- we don't lose the scc counter, bump it in the entry code for x.
	-- ToDo: for a multi-push we should really bump the counter for
	-- each of the intervening CCSs, not just the top one.
       ; when (not (isCurrentCCS ccs)) $
		emit (bumpSccCount curCCS)
       }

  | isCafCCS ccs
  = ASSERT(isToplevClosure closure_info)
    ASSERT(not re_entrant)
    do	{ 	-- This is just a special case of the isDerivedFromCurrentCCS
		-- case above.  We could delete this, but it's a micro
		-- optimisation and saves a bit of code.
	  emit (mkStore curCCSAddr enc_ccs)
	; emit (bumpSccCount node_ccs)
	}

  | otherwise
  = panic "enterCostCentre"
  where
    enc_ccs    = CmmLit (mkCCostCentreStack ccs)
    re_entrant = closureReEntrant closure_info
    node_ccs   = costCentreFrom (cmmOffsetB (CmmReg nodeReg) (-node_tag))
    is_box     = isBox body

    -- if this is a function, then node will be tagged; we must subract the tag
    node_tag = funTag closure_info

-- set the current CCS when entering a PAP
enterCostCentrePAP :: CmmExpr -> FCode ()
enterCostCentrePAP closure = 
  ifProfiling $ do 
    enter_ccs_fun (costCentreFrom closure)
    enteringPAP 1
  
enterCostCentreThunk :: CmmExpr -> FCode ()
enterCostCentreThunk closure = 
  ifProfiling $ do 
    emit $ mkStore curCCSAddr (costCentreFrom closure)

enter_ccs_fun :: CmmExpr -> FCode ()
enter_ccs_fun stack = emitRtsCall rtsPackageId (fsLit "EnterFunCCS") [(stack,AddrHint)] False
			-- ToDo: vols

enter_ccs_fsub :: FCode ()
enter_ccs_fsub = enteringPAP 0

-- When entering a PAP, EnterFunCCS is called by both the PAP entry
-- code and the function entry code; we don't want the function's
-- entry code to also update CCCS in the event that it was called via
-- a PAP, so we set the flag entering_PAP to indicate that we are
-- entering via a PAP.
enteringPAP :: Integer -> FCode ()
enteringPAP n
  = emit (mkStore (CmmLit (CmmLabel (mkCmmDataLabel rtsPackageId (fsLit "entering_PAP"))))
		  (CmmLit (CmmInt n cIntWidth)))

ifProfiling :: FCode () -> FCode ()
ifProfiling code
  | opt_SccProfilingOn = code
  | otherwise	       = nopC

ifProfilingL :: [a] -> [a]
ifProfilingL xs
  | opt_SccProfilingOn = xs
  | otherwise	       = []


---------------------------------------------------------------
--	Initialising Cost Centres & CCSs
---------------------------------------------------------------

initCostCentres :: CollectedCCs -> FCode CmmAGraph
-- Emit the declarations, and return code to register them
initCostCentres (local_CCs, ___extern_CCs, singleton_CCSs)
  = getCode $ whenC opt_SccProfilingOn $
    do	{ mapM_ emitCostCentreDecl local_CCs
  	; mapM_ emitCostCentreStackDecl  singleton_CCSs 
	; emit $ catAGraphs $ map mkRegisterCC local_CCs
	; emit $ catAGraphs $ map mkRegisterCCS singleton_CCSs }


emitCostCentreDecl :: CostCentre -> FCode ()
emitCostCentreDecl cc = do 
  { label <- mkStringCLit (costCentreUserName cc)
  ; modl  <- mkStringCLit (Module.moduleNameString 
               	               (Module.moduleName (cc_mod cc)))
                -- All cost centres will be in the main package, since we
                -- don't normally use -auto-all or add SCCs to other packages.
                -- Hence don't emit the package name in the module here.
  ; let lits = [ zero,   	-- StgInt ccID,
	      	 label,	-- char *label,
	      	 modl,	-- char *module,
              	 zero,	-- StgWord time_ticks
              	 zero64,	-- StgWord64 mem_alloc
	      	 subsumed, -- StgInt is_caf
	      	 zero	-- struct _CostCentre *link
	       ] 
  ; emitDataLits (mkCCLabel cc) lits
  }
  where
	subsumed | isCafCC cc = mkIntCLit (ord 'c')  -- 'c' == is a CAF
		 | otherwise  = mkIntCLit (ord 'B')  -- 'B' == is boring

emitCostCentreStackDecl :: CostCentreStack -> FCode ()
emitCostCentreStackDecl ccs 
  = case maybeSingletonCCS ccs of
	Just cc -> emitDataLits (mkCCSLabel ccs) (mk_lits cc)
	Nothing -> pprPanic "emitCostCentreStackDecl" (ppr ccs)
  where
     mk_lits cc = zero : 
		  mkCCostCentre cc : 
		  replicate (sizeof_ccs_words - 2) zero
	-- Note: to avoid making any assumptions about how the
	-- C compiler (that compiles the RTS, in particular) does
	-- layouts of structs containing long-longs, simply
	-- pad out the struct with zero words until we hit the
	-- size of the overall struct (which we get via DerivedConstants.h)

zero :: CmmLit
zero = mkIntCLit 0
zero64 :: CmmLit
zero64 = CmmInt 0 W64

sizeof_ccs_words :: Int
sizeof_ccs_words 
    -- round up to the next word.
  | ms == 0   = ws
  | otherwise = ws + 1
  where
   (ws,ms) = SIZEOF_CostCentreStack `divMod` wORD_SIZE

-- ---------------------------------------------------------------------------
-- Registering CCs and CCSs

--   (cc)->link = CC_LIST;
--   CC_LIST = (cc);
--   (cc)->ccID = CC_ID++;

mkRegisterCC :: CostCentre -> CmmAGraph
mkRegisterCC cc
  = withTemp cInt $ \tmp -> 
    catAGraphs [
     mkStore (cmmOffsetB cc_lit oFFSET_CostCentre_link)
		 (CmmLoad cC_LIST bWord),
     mkStore cC_LIST cc_lit,
     mkAssign (CmmLocal tmp) (CmmLoad cC_ID cInt),
     mkStore (cmmOffsetB cc_lit oFFSET_CostCentre_ccID) (CmmReg (CmmLocal tmp)),
     mkStore cC_ID (cmmRegOffB (CmmLocal tmp) 1)
   ]
  where
	cc_lit = CmmLit (CmmLabel (mkCCLabel cc))

--  (ccs)->prevStack = CCS_LIST;
--  CCS_LIST = (ccs);
--  (ccs)->ccsID = CCS_ID++;

mkRegisterCCS :: CostCentreStack -> CmmAGraph
mkRegisterCCS ccs
  = withTemp cInt $ \ tmp ->
    catAGraphs [
     mkStore (cmmOffsetB ccs_lit oFFSET_CostCentreStack_prevStack) 
			(CmmLoad cCS_LIST bWord),
     mkStore cCS_LIST ccs_lit,
     mkAssign (CmmLocal tmp) (CmmLoad cCS_ID cInt),
     mkStore (cmmOffsetB ccs_lit oFFSET_CostCentreStack_ccsID) (CmmReg (CmmLocal tmp)),
     mkStore cCS_ID (cmmRegOffB (CmmLocal tmp) 1)
   ]
  where
    ccs_lit = CmmLit (CmmLabel (mkCCSLabel ccs))


cC_LIST, cC_ID :: CmmExpr
cC_LIST = CmmLit (CmmLabel (mkCmmDataLabel rtsPackageId (fsLit "CC_LIST")))
cC_ID   = CmmLit (CmmLabel (mkCmmDataLabel rtsPackageId (fsLit "CC_ID")))

cCS_LIST, cCS_ID :: CmmExpr
cCS_LIST = CmmLit (CmmLabel (mkCmmDataLabel rtsPackageId (fsLit "CCS_LIST")))
cCS_ID   = CmmLit (CmmLabel (mkCmmDataLabel rtsPackageId (fsLit "CCS_ID")))

-- ---------------------------------------------------------------------------
-- Set the current cost centre stack

emitSetCCC :: CostCentre -> FCode ()
emitSetCCC cc
  | not opt_SccProfilingOn = nopC
  | otherwise = do 
    tmp <- newTemp ccsType -- TODO FIXME NOW
    ASSERT( sccAbleCostCentre cc )
      pushCostCentre tmp curCCS cc
    emit (mkStore curCCSAddr (CmmReg (CmmLocal tmp)))
    when (isSccCountCostCentre cc) $ 
	 emit (bumpSccCount curCCS)

pushCostCentre :: LocalReg -> CmmExpr -> CostCentre -> FCode ()
pushCostCentre result ccs cc
  = emitRtsCallWithResult result AddrHint
	rtsPackageId
	(fsLit "PushCostCentre") [(ccs,AddrHint), 
				(CmmLit (mkCCostCentre cc), AddrHint)]
        False

bumpSccCount :: CmmExpr -> CmmAGraph
bumpSccCount ccs
  = addToMem REP_CostCentreStack_scc_count
	 (cmmOffsetB ccs oFFSET_CostCentreStack_scc_count) 1

-----------------------------------------------------------------------------
--
--		Lag/drag/void stuff
--
-----------------------------------------------------------------------------

--
-- Initial value for the LDV field in a static closure
--
staticLdvInit :: CmmLit
staticLdvInit = zeroCLit

--
-- Initial value of the LDV field in a dynamic closure
--
dynLdvInit :: CmmExpr
dynLdvInit =     -- (era << LDV_SHIFT) | LDV_STATE_CREATE  
  CmmMachOp mo_wordOr [
      CmmMachOp mo_wordShl [loadEra, CmmLit (mkIntCLit lDV_SHIFT) ],
      CmmLit (mkWordCLit lDV_STATE_CREATE)
  ]
        
--
-- Initialise the LDV word of a new closure
--
ldvRecordCreate :: CmmExpr -> FCode ()
ldvRecordCreate closure = emit $ mkStore (ldvWord closure) dynLdvInit

--
-- Called when a closure is entered, marks the closure as having been "used".
-- The closure is not an 'inherently used' one.
-- The closure is not IND or IND_OLDGEN because neither is considered for LDV
-- profiling.
--
ldvEnterClosure :: ClosureInfo -> FCode ()
ldvEnterClosure closure_info = ldvEnter (cmmOffsetB (CmmReg nodeReg) (-tag))
  where tag = funTag closure_info
        -- don't forget to substract node's tag
  
ldvEnter :: CmmExpr -> FCode ()
-- Argument is a closure pointer
ldvEnter cl_ptr
  = ifProfiling $
     -- if (era > 0) {
     --    LDVW((c)) = (LDVW((c)) & LDV_CREATE_MASK) |
     --                era | LDV_STATE_USE }
    emit (mkCmmIfThenElse (CmmMachOp mo_wordUGt [loadEra, CmmLit zeroCLit])
		(mkStore ldv_wd new_ldv_wd)
		mkNop)
  where
        -- don't forget to substract node's tag
    ldv_wd = ldvWord cl_ptr
    new_ldv_wd = cmmOrWord (cmmAndWord (CmmLoad ldv_wd bWord)
				       (CmmLit (mkWordCLit lDV_CREATE_MASK)))
		 (cmmOrWord loadEra (CmmLit (mkWordCLit lDV_STATE_USE)))

loadEra :: CmmExpr 
loadEra = CmmMachOp (MO_UU_Conv cIntWidth wordWidth)
	  [CmmLoad (mkLblExpr (mkCmmDataLabel rtsPackageId (fsLit "era"))) cInt]

ldvWord :: CmmExpr -> CmmExpr
-- Takes the address of a closure, and returns 
-- the address of the LDV word in the closure
ldvWord closure_ptr = cmmOffsetB closure_ptr oFFSET_StgHeader_ldvw

-- LDV constants, from ghc/includes/Constants.h
lDV_SHIFT :: Int
lDV_SHIFT = LDV_SHIFT
--lDV_STATE_MASK :: StgWord
--lDV_STATE_MASK   = LDV_STATE_MASK
lDV_CREATE_MASK :: StgWord
lDV_CREATE_MASK  = LDV_CREATE_MASK
--lDV_LAST_MASK :: StgWord
--lDV_LAST_MASK    = LDV_LAST_MASK
lDV_STATE_CREATE :: StgWord
lDV_STATE_CREATE = LDV_STATE_CREATE
lDV_STATE_USE :: StgWord
lDV_STATE_USE    = LDV_STATE_USE