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|
-----------------------------------------------------------------------------
--
-- Stg to C-- code generation: the binding environment
--
-- (c) The University of Glasgow 2004-2006
--
-----------------------------------------------------------------------------
module GHC.StgToCmm.Env (
CgIdInfo,
litIdInfo, lneIdInfo, rhsIdInfo, mkRhsInit,
idInfoToAmode,
addBindC, addBindsC,
bindArgsToRegs, bindToReg, rebindToReg,
bindArgToReg, idToReg,
getCgIdInfo, getCgInfo_maybe,
maybeLetNoEscape,
) where
import GHC.Prelude
import GHC.Platform
import GHC.StgToCmm.Monad
import GHC.StgToCmm.Closure
import GHC.Cmm.CLabel
import GHC.Cmm.BlockId
import GHC.Cmm.Expr
import GHC.Cmm.Utils
import GHC.Types.Id
import GHC.Cmm.Graph
import GHC.Types.Name
import GHC.Core.Type
import GHC.Core.TyCo.Compare( eqType )
import GHC.Builtin.Types.Prim
import GHC.Types.Unique.FM
import GHC.Types.Var.Env
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Utils.Panic.Plain
import GHC.Builtin.Names (getUnique)
-------------------------------------
-- Manipulating CgIdInfo
-------------------------------------
mkCgIdInfo :: Id -> LambdaFormInfo -> CmmExpr -> CgIdInfo
mkCgIdInfo id lf expr
= CgIdInfo { cg_id = id, cg_lf = lf
, cg_loc = CmmLoc expr }
litIdInfo :: Platform -> Id -> LambdaFormInfo -> CmmLit -> CgIdInfo
litIdInfo platform id lf lit
= CgIdInfo { cg_id = id, cg_lf = lf
, cg_loc = CmmLoc (addDynTag platform (CmmLit lit) tag) }
where
tag = lfDynTag platform lf
lneIdInfo :: Platform -> Id -> [NonVoid Id] -> CgIdInfo
lneIdInfo platform id regs
= CgIdInfo { cg_id = id, cg_lf = lf
, cg_loc = LneLoc blk_id (map (idToReg platform) regs) }
where
lf = mkLFLetNoEscape
blk_id = mkBlockId (idUnique id)
rhsIdInfo :: Id -> LambdaFormInfo -> FCode (CgIdInfo, LocalReg)
rhsIdInfo id lf_info
= do platform <- getPlatform
reg <- newTemp (gcWord platform)
return (mkCgIdInfo id lf_info (CmmReg (CmmLocal reg)), reg)
mkRhsInit :: Platform -> LocalReg -> LambdaFormInfo -> CmmExpr -> CmmAGraph
mkRhsInit platform reg lf_info expr
= mkAssign (CmmLocal reg) (addDynTag platform expr (lfDynTag platform lf_info))
idInfoToAmode :: CgIdInfo -> CmmExpr
-- Returns a CmmExpr for the *tagged* pointer
idInfoToAmode CgIdInfo { cg_loc = CmmLoc e } = e
idInfoToAmode cg_info
= pprPanic "idInfoToAmode" (ppr (cg_id cg_info)) -- LneLoc
-- | A tag adds a byte offset to the pointer
addDynTag :: Platform -> CmmExpr -> DynTag -> CmmExpr
addDynTag = cmmOffsetB
maybeLetNoEscape :: CgIdInfo -> Maybe (BlockId, [LocalReg])
maybeLetNoEscape CgIdInfo { cg_loc = LneLoc blk_id args} = Just (blk_id, args)
maybeLetNoEscape _other = Nothing
---------------------------------------------------------
-- The binding environment
--
-- There are three basic routines, for adding (addBindC),
-- modifying(modifyBindC) and looking up (getCgIdInfo) bindings.
---------------------------------------------------------
addBindC :: CgIdInfo -> FCode ()
addBindC stuff_to_bind = do
binds <- getBinds
setBinds $ extendVarEnv binds (cg_id stuff_to_bind) stuff_to_bind
addBindsC :: [CgIdInfo] -> FCode ()
addBindsC new_bindings = do
binds <- getBinds
let new_binds = foldl' (\ binds info -> extendVarEnv binds (cg_id info) info)
binds
new_bindings
setBinds new_binds
-- Inside GHC the average module creates 385 external references
-- with notable cgIdInfo (so not generated by mkLFArgument).
-- On average 200 of these are covered by True/False/[]
-- and nullary constructors make up ~80.
-- One would think it would be worthwhile to cache these.
-- Sadly it's not. See #16937
getCgIdInfo :: Id -> FCode CgIdInfo
getCgIdInfo id
= do { platform <- getPlatform
; local_binds <- getBinds -- Try local bindings first
; case lookupVarEnv local_binds id of {
Just info -> -- pprTrace "getCgIdInfoLocal" (ppr id) $
return info ;
Nothing -> do {
-- Should be imported; make up a CgIdInfo for it
let name = idName id
; if isExternalName name then
let ext_lbl
| isBoxedType (idType id)
= mkClosureLabel name $ idCafInfo id
| isUnliftedType (idType id)
-- An unlifted external Id must refer to a top-level
-- string literal. See Note [Bytes label] in "GHC.Cmm.CLabel".
= assert (idType id `eqType` addrPrimTy) $
mkBytesLabel name
| otherwise
= pprPanic "GHC.StgToCmm.Env: label not found" (ppr id <+> dcolon <+> ppr (idType id))
in return $
litIdInfo platform id (mkLFImported id) (CmmLabel ext_lbl)
else
cgLookupPanic id -- Bug
}}}
-- | Retrieve cg info for a name if it already exists.
getCgInfo_maybe :: Name -> FCode (Maybe CgIdInfo)
getCgInfo_maybe name
= do { local_binds <- getBinds -- Try local bindings first
; return $ lookupVarEnv_Directly local_binds (getUnique name) }
cgLookupPanic :: Id -> FCode a
cgLookupPanic id
= do local_binds <- getBinds
pprPanic "GHC.StgToCmm.Env: variable not found"
(vcat [ppr id,
text "local binds for:",
pprUFM local_binds $ \infos ->
vcat [ ppr (cg_id info) | info <- infos ]
])
------------------------------------------------------------------------
-- Interface functions for binding and re-binding names
------------------------------------------------------------------------
bindToReg :: NonVoid Id -> LambdaFormInfo -> FCode LocalReg
-- Bind an Id to a fresh LocalReg
bindToReg nvid@(NonVoid id) lf_info
= do platform <- getPlatform
let reg = idToReg platform nvid
addBindC (mkCgIdInfo id lf_info (CmmReg (CmmLocal reg)))
return reg
rebindToReg :: NonVoid Id -> FCode LocalReg
-- Like bindToReg, but the Id is already in scope, so
-- get its LF info from the envt
rebindToReg nvid@(NonVoid id)
= do { info <- getCgIdInfo id
; bindToReg nvid (cg_lf info) }
bindArgToReg :: NonVoid Id -> FCode LocalReg
bindArgToReg nvid@(NonVoid id) = bindToReg nvid (mkLFArgument id)
bindArgsToRegs :: [NonVoid Id] -> FCode [LocalReg]
bindArgsToRegs = mapM bindArgToReg
idToReg :: Platform -> NonVoid Id -> LocalReg
-- Make a register from an Id, typically a function argument,
-- free variable, or case binder
--
-- We re-use the Unique from the Id to make it easier to see what is going on
--
-- By now the Ids should be uniquely named; else one would worry
-- about accidental collision
idToReg platform (NonVoid id)
= LocalReg (idUnique id)
(primRepCmmType platform (idPrimRep id))
|
