ghc-9.12.1: GHC/StgToCmm/Prof.hs
-----------------------------------------------------------------------------
--
-- Code generation for profiling
--
-- (c) The University of Glasgow 2004-2006
--
-----------------------------------------------------------------------------
module GHC.StgToCmm.Prof (
initCostCentres, ccType, ccsType,
mkCCostCentre, mkCCostCentreStack,
-- infoTablePRov
initInfoTableProv,
-- Cost-centre Profiling
dynProfHdr, profDynAlloc, profAlloc, staticProfHdr, initUpdFrameProf,
enterCostCentreThunk, enterCostCentreFun,
costCentreFrom,
storeCurCCS,
emitSetCCC,
saveCurrentCostCentre, restoreCurrentCostCentre,
-- Lag/drag/void stuff
ldvEnter, ldvEnterClosure, profHeaderCreate
) where
import GHC.Prelude
import GHC.Platform
import GHC.Platform.Profile
import GHC.StgToCmm.Closure
import GHC.StgToCmm.Config
import GHC.StgToCmm.InfoTableProv
import GHC.StgToCmm.Utils
import GHC.StgToCmm.Monad
import GHC.StgToCmm.Lit
import GHC.Runtime.Heap.Layout
import GHC.Cmm.Graph
import GHC.Cmm
import GHC.Cmm.Utils
import GHC.Cmm.CLabel
import GHC.Types.Unique.DSM
import GHC.Types.CostCentre
import GHC.Types.IPE
import GHC.Types.ForeignStubs
import GHC.Data.FastString
import GHC.Unit.Module as Module
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Driver.CodeOutput ( ipInitCode )
import GHC.Utils.Encoding
import Control.Monad
import Data.Char (ord)
import GHC.Utils.Monad (whenM)
-----------------------------------------------------------------------------
--
-- Cost-centre-stack Profiling
--
-----------------------------------------------------------------------------
-- Expression representing the current cost centre stack
ccsType :: Platform -> CmmType -- Type of a cost-centre stack
ccsType = bWord
ccType :: Platform -> CmmType -- Type of a cost centre
ccType = bWord
storeCurCCS :: Platform -> CmmExpr -> CmmAGraph
storeCurCCS platform = mkAssign (cccsReg platform)
mkCCostCentre :: CostCentre -> CmmLit
mkCCostCentre cc = CmmLabel (mkCCLabel cc)
mkCCostCentreStack :: CostCentreStack -> CmmLit
mkCCostCentreStack ccs = CmmLabel (mkCCSLabel ccs)
costCentreFrom :: Platform
-> CmmExpr -- A closure pointer
-> CmmExpr -- The cost centre from that closure
costCentreFrom platform cl = CmmLoad (cmmOffsetB platform cl (pc_OFFSET_StgHeader_ccs (platformConstants platform))) (ccsType platform) NaturallyAligned
-- | The profiling header words in a static closure
staticProfHdr :: Profile -> CostCentreStack -> [CmmLit]
staticProfHdr profile ccs
| profileIsProfiling profile = [mkCCostCentreStack ccs, staticProfHeaderInit platform]
| otherwise = []
where platform = profilePlatform profile
-- | Profiling header words in a dynamic closure
dynProfHdr :: Profile -> CmmExpr -> [CmmExpr]
dynProfHdr profile ccs
| profileIsProfiling profile = [ccs, dynProfInit (profilePlatform profile)]
| otherwise = []
-- | Initialise the profiling field of an update frame
initUpdFrameProf :: CmmExpr -> FCode ()
initUpdFrameProf frame
= ifProfiling $ -- frame->header.prof.ccs = CCCS
do platform <- getPlatform
emitStore (cmmOffset platform frame (pc_OFFSET_StgHeader_ccs (platformConstants platform))) (cccsExpr platform)
-- 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
= do sccProfilingEnabled <- stgToCmmSCCProfiling <$> getStgToCmmConfig
platform <- getPlatform
if not sccProfilingEnabled
then return Nothing
else do local_cc <- newTemp (ccType platform)
emitAssign (CmmLocal local_cc) (cccsExpr platform)
return (Just local_cc)
restoreCurrentCostCentre :: Platform -> Maybe LocalReg -> FCode ()
restoreCurrentCostCentre _ Nothing
= return ()
restoreCurrentCostCentre platform (Just local_cc)
= emit (storeCurCCS platform (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 :: SMRep -> CmmExpr -> FCode ()
profDynAlloc rep ccs
= ifProfiling $
do profile <- getProfile
let platform = profilePlatform profile
profAlloc (mkIntExpr platform (heapClosureSizeW profile rep)) 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 $
do profile <- getProfile
let platform = profilePlatform profile
let alloc_rep = rEP_CostCentreStack_mem_alloc platform
emit $ addToMemE alloc_rep
(cmmOffsetB platform ccs (pc_OFFSET_CostCentreStack_mem_alloc (platformConstants platform)))
(CmmMachOp (MO_UU_Conv (wordWidth platform) (typeWidth alloc_rep))
-- subtract the "profiling overhead", which is the
-- profiling header in a closure.
[CmmMachOp (mo_wordSub platform) [ words, mkIntExpr platform (profHdrSize profile)]]
)
-- -----------------------------------------------------------------------
-- Setting the current cost centre on entry to a closure
enterCostCentreThunk :: CmmExpr -> FCode ()
enterCostCentreThunk closure =
ifProfiling $ do
platform <- getPlatform
emit $ storeCurCCS platform (costCentreFrom platform closure)
enterCostCentreFun :: CostCentreStack -> CmmExpr -> FCode ()
enterCostCentreFun ccs closure = ifProfiling $
when (isCurrentCCS ccs) $
do platform <- getPlatform
emitRtsCall
rtsUnitId
(fsLit "enterFunCCS")
[(baseExpr platform, AddrHint), (costCentreFrom platform closure, AddrHint)]
False
-- otherwise we have a top-level function, nothing to do
ifProfiling :: FCode () -> FCode ()
ifProfiling = whenM (stgToCmmSCCProfiling <$> getStgToCmmConfig)
---------------------------------------------------------------
-- Initialising Cost Centres & CCSs
---------------------------------------------------------------
initCostCentres :: CollectedCCs -> FCode ()
-- Emit the declarations
initCostCentres (local_CCs, singleton_CCSs)
= ifProfiling $ do
mapM_ emitCostCentreDecl local_CCs
mapM_ emitCostCentreStackDecl singleton_CCSs
emitCostCentreDecl :: CostCentre -> FCode ()
emitCostCentreDecl cc = do
{ ctx <- stgToCmmContext <$> getStgToCmmConfig
; platform <- getPlatform
; let is_caf | isCafCC cc = mkIntCLit platform (ord 'c') -- 'c' == is a CAF
| otherwise = zero platform
-- NB. bytesFS: we want the UTF-8 bytes here (#5559)
; label <- newByteStringCLit (bytesFS $ costCentreUserNameFS cc)
; modl <- newByteStringCLit (bytesFS $ moduleNameFS
$ moduleName
$ cc_mod cc)
; loc <- newByteStringCLit $ utf8EncodeByteString $
renderWithContext ctx (ppr $! costCentreSrcSpan cc)
; let
lits = [ zero platform, -- StgInt ccID,
label, -- char *label,
modl, -- char *module,
loc, -- char *srcloc,
zero64, -- StgWord64 mem_alloc
zero platform, -- StgWord time_ticks
is_caf, -- StgInt is_caf
zero platform -- struct _CostCentre *link
]
; emitDataLits (mkCCLabel cc) lits
}
emitCostCentreStackDecl :: CostCentreStack -> FCode ()
emitCostCentreStackDecl ccs
= case maybeSingletonCCS ccs of
Just cc ->
do platform <- getPlatform
let mk_lits cc = zero platform :
mkCCostCentre cc :
replicate (sizeof_ccs_words platform - 2) (zero platform)
-- 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)
emitDataLits (mkCCSLabel ccs) (mk_lits cc)
Nothing -> pprPanic "emitCostCentreStackDecl" (ppr ccs)
zero :: Platform -> CmmLit
zero platform = mkIntCLit platform 0
zero64 :: CmmLit
zero64 = CmmInt 0 W64
sizeof_ccs_words :: Platform -> Int
sizeof_ccs_words platform
-- round up to the next word.
| ms == 0 = ws
| otherwise = ws + 1
where
(ws,ms) = pc_SIZEOF_CostCentreStack (platformConstants platform) `divMod` platformWordSizeInBytes platform
-- | Emit info-table provenance declarations and track IPE stats.
--
-- Note that the stats passed to this function will (rather, should) only ever
-- contain stats for skipped STACK info tables accumulated in
-- 'generateCgIPEStub'.
initInfoTableProv :: IPEStats -> [CmmInfoTable] -> InfoTableProvMap -> DUniqSupply -> FCode (Maybe (IPEStats, CStub), DUniqSupply)
initInfoTableProv stats infos itmap dus
= do
cfg <- getStgToCmmConfig
let (stats', ents) = convertInfoProvMap cfg this_mod itmap stats infos
info_table = stgToCmmInfoTableMap cfg
platform = stgToCmmPlatform cfg
this_mod = stgToCmmThisModule cfg
case ents of
[] -> return (Nothing, dus)
_ -> do
-- Emit IPE buffer
dus' <- emitIpeBufferListNode this_mod ents dus
-- Create the C stub which initialises the IPE map
return (Just (stats', ipInitCode info_table platform this_mod), dus')
-- ---------------------------------------------------------------------------
-- Set the current cost centre stack
emitSetCCC :: CostCentre -> Bool -> Bool -> FCode ()
emitSetCCC cc tick push = ifProfiling $
do platform <- getPlatform
tmp <- newTemp (ccsType platform)
pushCostCentre tmp (cccsExpr platform) cc
when tick $ emit (bumpSccCount platform (CmmReg (CmmLocal tmp)))
when push $ emit (storeCurCCS platform (CmmReg (CmmLocal tmp)))
pushCostCentre :: LocalReg -> CmmExpr -> CostCentre -> FCode ()
pushCostCentre result ccs cc
= emitRtsCallWithResult result AddrHint
rtsUnitId
(fsLit "pushCostCentre") [(ccs,AddrHint),
(CmmLit (mkCCostCentre cc), AddrHint)]
False
bumpSccCount :: Platform -> CmmExpr -> CmmAGraph
bumpSccCount platform ccs
= addToMem (rEP_CostCentreStack_scc_count platform)
(cmmOffsetB platform ccs (pc_OFFSET_CostCentreStack_scc_count (platformConstants platform))) 1
-----------------------------------------------------------------------------
--
-- Profiling header stuff
--
-----------------------------------------------------------------------------
-- Header initialisation for static objects happens to coicincide for the
-- three uses of the header
-- * LDV profiling = 0 (era = 0, LDV_STATE_CREATE)
-- * Eras profiling = 0 (user_era = 0, ignored by profiler)
-- * Retainer profiling = 0
staticProfHeaderInit :: Platform -> CmmLit
staticProfHeaderInit plat = zeroCLit plat
-- Dynamic initialisation
dynErasInit :: Platform -> CmmExpr
dynErasInit platform = loadUserEra platform
dynLdvInit :: Platform -> CmmExpr
dynLdvInit platform =
-- (era << LDV_SHIFT) | LDV_STATE_CREATE
CmmMachOp (mo_wordOr platform) [
CmmMachOp (mo_wordShl platform) [loadEra platform, mkIntExpr platform (pc_LDV_SHIFT (platformConstants platform))],
CmmLit (mkWordCLit platform (pc_ILDV_STATE_CREATE (platformConstants platform)))
]
-- | If LDV profiling the user_era = 0
-- , if eras profiling then (ldv)era = 0, so we can initialise correctly by OR the two expressions.
dynProfInit :: Platform -> CmmExpr
dynProfInit platform = CmmMachOp (mo_wordOr platform) [(dynLdvInit platform), dynErasInit platform]
-- | Initialise the profiling word of a new dynamic closure
-- * When LDV profiling is enabled (era > 0) - Initialise to the LDV word
-- * When eras profiling is enabled (user_era > 0) - Initialise to current user_era
profHeaderCreate :: CmmExpr -> FCode ()
profHeaderCreate closure = do
platform <- getPlatform
let prof_header_wd = profHeaderWord platform closure
let check_ldv = mkCmmIfThenElse (CmmMachOp (mo_wordUGt platform) [loadEra platform, CmmLit (zeroCLit platform)])
let check_eras = mkCmmIfThenElse (CmmMachOp (mo_wordUGt platform) [loadUserEra platform, CmmLit (zeroCLit platform)])
-- Case 2: user_era > 0, eras profiling is enabled
check_1 <- check_eras (mkStore prof_header_wd (dynErasInit platform)) mkNop
-- Case 1: era > 0, LDV profiling is enabled
check_2 <- check_ldv (mkStore prof_header_wd (dynLdvInit platform)) check_1
emit check_2
--
-- | 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@ because that is not considered for LDV profiling.
--
ldvEnterClosure :: ClosureInfo -> CmmReg -> FCode ()
ldvEnterClosure closure_info node_reg = do
platform <- getPlatform
let tag = funTag platform closure_info
-- don't forget to subtract node's tag
ldvEnter (cmmOffsetB platform (CmmReg node_reg) (-tag))
ldvEnter :: CmmExpr -> FCode ()
-- Argument is a closure pointer
ldvEnter cl_ptr = do
platform <- getPlatform
let constants = platformConstants platform
-- don't forget to subtract node's tag
ldv_wd = profHeaderWord platform cl_ptr
new_ldv_wd = cmmOrWord platform
(cmmAndWord platform (cmmLoadBWord platform ldv_wd)
(CmmLit (mkWordCLit platform (pc_ILDV_CREATE_MASK constants))))
(cmmOrWord platform (loadEra platform) (CmmLit (mkWordCLit platform (pc_ILDV_STATE_USE constants))))
ifProfiling $ do
-- if (era > 0) {
-- LDVW((c)) = (LDVW((c)) & LDV_CREATE_MASK) |
-- era | LDV_STATE_USE }
emit =<< mkCmmIfThenElse (CmmMachOp (mo_wordUGt platform) [loadEra platform, CmmLit (zeroCLit platform)])
(mkStore ldv_wd new_ldv_wd)
mkNop
loadEra :: Platform -> CmmExpr
loadEra platform = CmmMachOp (MO_UU_Conv (cIntWidth platform) (wordWidth platform))
[CmmLoad (mkLblExpr (mkRtsCmmDataLabel (fsLit "era")))
(cInt platform)
NaturallyAligned]
loadUserEra :: Platform -> CmmExpr
loadUserEra platform = CmmLoad (mkLblExpr (mkRtsCmmDataLabel (fsLit "user_era")))
(bWord platform)
NaturallyAligned
-- | Takes the address of a closure, and returns
-- the address of the prof header word in the closure (this is used to store LDV info,
-- retainer profiling info and eras profiling info).
profHeaderWord :: Platform -> CmmExpr -> CmmExpr
profHeaderWord platform closure_ptr
= cmmOffsetB platform closure_ptr (pc_OFFSET_StgHeader_ldvw (platformConstants platform))