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{-
(c) The GRASP/AQUA Project, Glasgow University, 1993-1998
\section[SimplStg]{Driver for simplifying @STG@ programs}
-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeFamilies #-}
module GHC.Stg.Pipeline ( stg2stg ) where
#include "HsVersions.h"
import GHC.Prelude
import GHC.Stg.Syntax
import GHC.Stg.Lint ( lintStgTopBindings )
import GHC.Stg.Stats ( showStgStats )
import GHC.Stg.DepAnal ( depSortStgPgm )
import GHC.Stg.Unarise ( unarise )
import GHC.Stg.CSE ( stgCse )
import GHC.Stg.Lift ( stgLiftLams )
import GHC.Unit.Module ( Module )
import GHC.Driver.Session
import GHC.Utils.Error
import GHC.Types.Unique.Supply
import GHC.Utils.Outputable
import GHC.Utils.Panic
import Control.Monad
import Control.Monad.IO.Class
import Control.Monad.Trans.State.Strict
newtype StgM a = StgM { _unStgM :: StateT Char IO a }
deriving (Functor, Applicative, Monad, MonadIO)
instance MonadUnique StgM where
getUniqueSupplyM = StgM $ do { mask <- get
; liftIO $! mkSplitUniqSupply mask}
getUniqueM = StgM $ do { mask <- get
; liftIO $! uniqFromMask mask}
runStgM :: Char -> StgM a -> IO a
runStgM mask (StgM m) = evalStateT m mask
stg2stg :: DynFlags -- includes spec of what stg-to-stg passes to do
-> Module -- module being compiled
-> [StgTopBinding] -- input program
-> IO [StgTopBinding] -- output program
stg2stg dflags this_mod binds
= do { dump_when Opt_D_dump_stg "STG:" binds
; showPass dflags "Stg2Stg"
-- Do the main business!
; binds' <- runStgM 'g' $
foldM do_stg_pass binds (getStgToDo dflags)
-- Dependency sort the program as last thing. The program needs to be
-- in dependency order for the SRT algorithm to work (see
-- CmmBuildInfoTables, which also includes a detailed description of
-- the algorithm), and we don't guarantee that the program is already
-- sorted at this point. #16192 is for simplifier not preserving
-- dependency order. We also don't guarantee that StgLiftLams will
-- preserve the order or only create minimal recursive groups, so a
-- sorting pass is necessary.
; let binds_sorted = depSortStgPgm this_mod binds'
; return binds_sorted
}
where
stg_linter unarised
| gopt Opt_DoStgLinting dflags
= lintStgTopBindings dflags this_mod unarised
| otherwise
= \ _whodunnit _binds -> return ()
-------------------------------------------
do_stg_pass :: [StgTopBinding] -> StgToDo -> StgM [StgTopBinding]
do_stg_pass binds to_do
= case to_do of
StgDoNothing ->
return binds
StgStats ->
trace (showStgStats binds) (return binds)
StgCSE -> do
let binds' = {-# SCC "StgCse" #-} stgCse binds
end_pass "StgCse" binds'
StgLiftLams -> do
us <- getUniqueSupplyM
let binds' = {-# SCC "StgLiftLams" #-} stgLiftLams dflags us binds
end_pass "StgLiftLams" binds'
StgUnarise -> do
us <- getUniqueSupplyM
liftIO (stg_linter False "Pre-unarise" binds)
let binds' = unarise us binds
liftIO (dump_when Opt_D_dump_stg_unarised "Unarised STG:" binds')
liftIO (stg_linter True "Unarise" binds')
return binds'
opts = initStgPprOpts dflags
dump_when flag header binds
= dumpIfSet_dyn dflags flag header FormatSTG (pprStgTopBindings opts binds)
end_pass what binds2
= liftIO $ do -- report verbosely, if required
dumpIfSet_dyn dflags Opt_D_verbose_stg2stg what
FormatSTG (vcat (map (pprStgTopBinding opts) binds2))
stg_linter False what binds2
return binds2
-- -----------------------------------------------------------------------------
-- StgToDo: abstraction of stg-to-stg passes to run.
-- | Optional Stg-to-Stg passes.
data StgToDo
= StgCSE
-- ^ Common subexpression elimination
| StgLiftLams
-- ^ Lambda lifting closure variables, trading stack/register allocation for
-- heap allocation
| StgStats
| StgUnarise
-- ^ Mandatory unarise pass, desugaring unboxed tuple and sum binders
| StgDoNothing
-- ^ Useful for building up 'getStgToDo'
deriving Eq
-- | Which Stg-to-Stg passes to run. Depends on flags, ways etc.
getStgToDo :: DynFlags -> [StgToDo]
getStgToDo dflags =
filter (/= StgDoNothing)
[ mandatory StgUnarise
-- Important that unarisation comes first
-- See Note [StgCse after unarisation] in GHC.Stg.CSE
, optional Opt_StgCSE StgCSE
, optional Opt_StgLiftLams StgLiftLams
, optional Opt_StgStats StgStats
] where
optional opt = runWhen (gopt opt dflags)
mandatory = id
runWhen :: Bool -> StgToDo -> StgToDo
runWhen True todo = todo
runWhen _ _ = StgDoNothing
|
