{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE UndecidableInstances #-}

module GHC.Cmm.Expr
    ( CmmExpr(..), cmmExprType, cmmExprWidth, cmmExprAlignment, maybeInvertCmmExpr
    , CmmReg(..), cmmRegType, cmmRegWidth
    , CmmLit(..), cmmLitType
    , LocalReg(..), localRegType
    , GlobalReg(..), isArgReg, globalRegType
    , spReg, hpReg, spLimReg, hpLimReg, nodeReg
    , currentTSOReg, currentNurseryReg, hpAllocReg, cccsReg
    , node, baseReg
    , VGcPtr(..)

    , DefinerOfRegs, UserOfRegs
    , foldRegsDefd, foldRegsUsed
    , foldLocalRegsDefd, foldLocalRegsUsed

    , RegSet, LocalRegSet, GlobalRegSet
    , emptyRegSet, elemRegSet, extendRegSet, deleteFromRegSet, mkRegSet
    , plusRegSet, minusRegSet, timesRegSet, sizeRegSet, nullRegSet
    , regSetToList

    , Area(..)
    , module GHC.Cmm.MachOp
    , module GHC.Cmm.Type
    )
where

import GHC.Prelude

import GHC.Platform
import GHC.Cmm.BlockId
import GHC.Cmm.CLabel
import GHC.Cmm.MachOp
import GHC.Cmm.Type
import GHC.Driver.Session
import GHC.Utils.Outputable (panic)
import GHC.Types.Unique

import Data.Set (Set)
import qualified Data.Set as Set

import GHC.Types.Basic (Alignment, mkAlignment, alignmentOf)

-----------------------------------------------------------------------------
--              CmmExpr
-- An expression.  Expressions have no side effects.
-----------------------------------------------------------------------------

data CmmExpr
  = CmmLit CmmLit               -- Literal
  | CmmLoad !CmmExpr !CmmType   -- Read memory location
  | CmmReg !CmmReg              -- Contents of register
  | CmmMachOp MachOp [CmmExpr]  -- Machine operation (+, -, *, etc.)
  | CmmStackSlot Area {-# UNPACK #-} !Int
                                -- addressing expression of a stack slot
                                -- See Note [CmmStackSlot aliasing]
  | CmmRegOff !CmmReg Int
        -- CmmRegOff reg i
        --        ** is shorthand only, meaning **
        -- CmmMachOp (MO_Add rep) [x, CmmLit (CmmInt (fromIntegral i) rep)]
        --      where rep = typeWidth (cmmRegType reg)

instance Eq CmmExpr where       -- Equality ignores the types
  CmmLit CmmLit
l1          == :: CmmExpr -> CmmExpr -> Bool
== CmmLit CmmLit
l2          = CmmLit
l1CmmLit -> CmmLit -> Bool
forall a. Eq a => a -> a -> Bool
==CmmLit
l2
  CmmLoad CmmExpr
e1 CmmType
_       == CmmLoad CmmExpr
e2 CmmType
_       = CmmExpr
e1CmmExpr -> CmmExpr -> Bool
forall a. Eq a => a -> a -> Bool
==CmmExpr
e2
  CmmReg CmmReg
r1          == CmmReg CmmReg
r2          = CmmReg
r1CmmReg -> CmmReg -> Bool
forall a. Eq a => a -> a -> Bool
==CmmReg
r2
  CmmRegOff CmmReg
r1 Int
i1    == CmmRegOff CmmReg
r2 Int
i2    = CmmReg
r1CmmReg -> CmmReg -> Bool
forall a. Eq a => a -> a -> Bool
==CmmReg
r2 Bool -> Bool -> Bool
&& Int
i1Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
i2
  CmmMachOp MachOp
op1 [CmmExpr]
es1  == CmmMachOp MachOp
op2 [CmmExpr]
es2  = MachOp
op1MachOp -> MachOp -> Bool
forall a. Eq a => a -> a -> Bool
==MachOp
op2 Bool -> Bool -> Bool
&& [CmmExpr]
es1[CmmExpr] -> [CmmExpr] -> Bool
forall a. Eq a => a -> a -> Bool
==[CmmExpr]
es2
  CmmStackSlot Area
a1 Int
i1 == CmmStackSlot Area
a2 Int
i2 = Area
a1Area -> Area -> Bool
forall a. Eq a => a -> a -> Bool
==Area
a2 Bool -> Bool -> Bool
&& Int
i1Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
i2
  CmmExpr
_e1                == CmmExpr
_e2                = Bool
False

data CmmReg
  = CmmLocal  {-# UNPACK #-} !LocalReg
  | CmmGlobal GlobalReg
  deriving( CmmReg -> CmmReg -> Bool
(CmmReg -> CmmReg -> Bool)
-> (CmmReg -> CmmReg -> Bool) -> Eq CmmReg
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: CmmReg -> CmmReg -> Bool
$c/= :: CmmReg -> CmmReg -> Bool
== :: CmmReg -> CmmReg -> Bool
$c== :: CmmReg -> CmmReg -> Bool
Eq, Eq CmmReg
Eq CmmReg
-> (CmmReg -> CmmReg -> Ordering)
-> (CmmReg -> CmmReg -> Bool)
-> (CmmReg -> CmmReg -> Bool)
-> (CmmReg -> CmmReg -> Bool)
-> (CmmReg -> CmmReg -> Bool)
-> (CmmReg -> CmmReg -> CmmReg)
-> (CmmReg -> CmmReg -> CmmReg)
-> Ord CmmReg
CmmReg -> CmmReg -> Bool
CmmReg -> CmmReg -> Ordering
CmmReg -> CmmReg -> CmmReg
forall a.
Eq a
-> (a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
min :: CmmReg -> CmmReg -> CmmReg
$cmin :: CmmReg -> CmmReg -> CmmReg
max :: CmmReg -> CmmReg -> CmmReg
$cmax :: CmmReg -> CmmReg -> CmmReg
>= :: CmmReg -> CmmReg -> Bool
$c>= :: CmmReg -> CmmReg -> Bool
> :: CmmReg -> CmmReg -> Bool
$c> :: CmmReg -> CmmReg -> Bool
<= :: CmmReg -> CmmReg -> Bool
$c<= :: CmmReg -> CmmReg -> Bool
< :: CmmReg -> CmmReg -> Bool
$c< :: CmmReg -> CmmReg -> Bool
compare :: CmmReg -> CmmReg -> Ordering
$ccompare :: CmmReg -> CmmReg -> Ordering
Ord )

-- | A stack area is either the stack slot where a variable is spilled
-- or the stack space where function arguments and results are passed.
data Area
  = Old            -- See Note [Old Area]
  | Young {-# UNPACK #-} !BlockId  -- Invariant: must be a continuation BlockId
                   -- See Note [Continuation BlockId] in GHC.Cmm.Node.
  deriving (Area -> Area -> Bool
(Area -> Area -> Bool) -> (Area -> Area -> Bool) -> Eq Area
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: Area -> Area -> Bool
$c/= :: Area -> Area -> Bool
== :: Area -> Area -> Bool
$c== :: Area -> Area -> Bool
Eq, Eq Area
Eq Area
-> (Area -> Area -> Ordering)
-> (Area -> Area -> Bool)
-> (Area -> Area -> Bool)
-> (Area -> Area -> Bool)
-> (Area -> Area -> Bool)
-> (Area -> Area -> Area)
-> (Area -> Area -> Area)
-> Ord Area
Area -> Area -> Bool
Area -> Area -> Ordering
Area -> Area -> Area
forall a.
Eq a
-> (a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
min :: Area -> Area -> Area
$cmin :: Area -> Area -> Area
max :: Area -> Area -> Area
$cmax :: Area -> Area -> Area
>= :: Area -> Area -> Bool
$c>= :: Area -> Area -> Bool
> :: Area -> Area -> Bool
$c> :: Area -> Area -> Bool
<= :: Area -> Area -> Bool
$c<= :: Area -> Area -> Bool
< :: Area -> Area -> Bool
$c< :: Area -> Area -> Bool
compare :: Area -> Area -> Ordering
$ccompare :: Area -> Area -> Ordering
Ord)

{- Note [Old Area]
~~~~~~~~~~~~~~~~~~
There is a single call area 'Old', allocated at the extreme old
end of the stack frame (ie just younger than the return address)
which holds:
  * incoming (overflow) parameters,
  * outgoing (overflow) parameter to tail calls,
  * outgoing (overflow) result values
  * the update frame (if any)

Its size is the max of all these requirements.  On entry, the stack
pointer will point to the youngest incoming parameter, which is not
necessarily at the young end of the Old area.

End of note -}


{- Note [CmmStackSlot aliasing]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When do two CmmStackSlots alias?

 - T[old+N] aliases with U[young(L)+M] for all T, U, L, N and M
 - T[old+N] aliases with U[old+M] only if the areas actually overlap

Or more informally, different Areas may overlap with each other.

An alternative semantics, that we previously had, was that different
Areas do not overlap.  The problem that lead to redefining the
semantics of stack areas is described below.

e.g. if we had

    x = Sp[old + 8]
    y = Sp[old + 16]

    Sp[young(L) + 8]  = L
    Sp[young(L) + 16] = y
    Sp[young(L) + 24] = x
    call f() returns to L

if areas semantically do not overlap, then we might optimise this to

    Sp[young(L) + 8]  = L
    Sp[young(L) + 16] = Sp[old + 8]
    Sp[young(L) + 24] = Sp[old + 16]
    call f() returns to L

and now young(L) cannot be allocated at the same place as old, and we
are doomed to use more stack.

  - old+8  conflicts with young(L)+8
  - old+16 conflicts with young(L)+16 and young(L)+8

so young(L)+8 == old+24 and we get

    Sp[-8]  = L
    Sp[-16] = Sp[8]
    Sp[-24] = Sp[0]
    Sp -= 24
    call f() returns to L

However, if areas are defined to be "possibly overlapping" in the
semantics, then we cannot commute any loads/stores of old with
young(L), and we will be able to re-use both old+8 and old+16 for
young(L).

    x = Sp[8]
    y = Sp[0]

    Sp[8] = L
    Sp[0] = y
    Sp[-8] = x
    Sp = Sp - 8
    call f() returns to L

Now, the assignments of y go away,

    x = Sp[8]
    Sp[8] = L
    Sp[-8] = x
    Sp = Sp - 8
    call f() returns to L
-}

data CmmLit
  = CmmInt !Integer  Width
        -- Interpretation: the 2's complement representation of the value
        -- is truncated to the specified size.  This is easier than trying
        -- to keep the value within range, because we don't know whether
        -- it will be used as a signed or unsigned value (the CmmType doesn't
        -- distinguish between signed & unsigned).
  | CmmFloat  Rational Width
  | CmmVec [CmmLit]                     -- Vector literal
  | CmmLabel    CLabel                  -- Address of label
  | CmmLabelOff CLabel Int              -- Address of label + byte offset

        -- Due to limitations in the C backend, the following
        -- MUST ONLY be used inside the info table indicated by label2
        -- (label2 must be the info label), and label1 must be an
        -- SRT, a slow entrypoint or a large bitmap (see the Mangler)
        -- Don't use it at all unless tablesNextToCode.
        -- It is also used inside the NCG during when generating
        -- position-independent code.
  | CmmLabelDiffOff CLabel CLabel Int Width -- label1 - label2 + offset
        -- In an expression, the width just has the effect of MO_SS_Conv
        -- from wordWidth to the desired width.
        --
        -- In a static literal, the supported Widths depend on the
        -- architecture: wordWidth is supported on all
        -- architectures. Additionally W32 is supported on x86_64 when
        -- using the small memory model.

  | CmmBlock {-# UNPACK #-} !BlockId     -- Code label
        -- Invariant: must be a continuation BlockId
        -- See Note [Continuation BlockId] in GHC.Cmm.Node.

  | CmmHighStackMark -- A late-bound constant that stands for the max
                     -- #bytes of stack space used during a procedure.
                     -- During the stack-layout pass, CmmHighStackMark
                     -- is replaced by a CmmInt for the actual number
                     -- of bytes used
  deriving CmmLit -> CmmLit -> Bool
(CmmLit -> CmmLit -> Bool)
-> (CmmLit -> CmmLit -> Bool) -> Eq CmmLit
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: CmmLit -> CmmLit -> Bool
$c/= :: CmmLit -> CmmLit -> Bool
== :: CmmLit -> CmmLit -> Bool
$c== :: CmmLit -> CmmLit -> Bool
Eq

cmmExprType :: Platform -> CmmExpr -> CmmType
cmmExprType :: Platform -> CmmExpr -> CmmType
cmmExprType Platform
platform = \case
   (CmmLit CmmLit
lit)        -> Platform -> CmmLit -> CmmType
cmmLitType Platform
platform CmmLit
lit
   (CmmLoad CmmExpr
_ CmmType
rep)     -> CmmType
rep
   (CmmReg CmmReg
reg)        -> Platform -> CmmReg -> CmmType
cmmRegType Platform
platform CmmReg
reg
   (CmmMachOp MachOp
op [CmmExpr]
args) -> Platform -> MachOp -> [CmmType] -> CmmType
machOpResultType Platform
platform MachOp
op ((CmmExpr -> CmmType) -> [CmmExpr] -> [CmmType]
forall a b. (a -> b) -> [a] -> [b]
map (Platform -> CmmExpr -> CmmType
cmmExprType Platform
platform) [CmmExpr]
args)
   (CmmRegOff CmmReg
reg Int
_)   -> Platform -> CmmReg -> CmmType
cmmRegType Platform
platform CmmReg
reg
   (CmmStackSlot Area
_ Int
_)  -> Platform -> CmmType
bWord Platform
platform -- an address
   -- Careful though: what is stored at the stack slot may be bigger than
   -- an address

cmmLitType :: Platform -> CmmLit -> CmmType
cmmLitType :: Platform -> CmmLit -> CmmType
cmmLitType Platform
platform = \case
   (CmmInt Integer
_ Width
width)     -> Width -> CmmType
cmmBits  Width
width
   (CmmFloat Rational
_ Width
width)   -> Width -> CmmType
cmmFloat Width
width
   (CmmVec [])          -> String -> CmmType
forall a. String -> a
panic String
"cmmLitType: CmmVec []"
   (CmmVec (CmmLit
l:[CmmLit]
ls))      -> let ty :: CmmType
ty = Platform -> CmmLit -> CmmType
cmmLitType Platform
platform CmmLit
l
                          in if (CmmType -> Bool) -> [CmmType] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (CmmType -> CmmType -> Bool
`cmmEqType` CmmType
ty) ((CmmLit -> CmmType) -> [CmmLit] -> [CmmType]
forall a b. (a -> b) -> [a] -> [b]
map (Platform -> CmmLit -> CmmType
cmmLitType Platform
platform) [CmmLit]
ls)
                               then Int -> CmmType -> CmmType
cmmVec (Int
1Int -> Int -> Int
forall a. Num a => a -> a -> a
+[CmmLit] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [CmmLit]
ls) CmmType
ty
                               else String -> CmmType
forall a. String -> a
panic String
"cmmLitType: CmmVec"
   (CmmLabel CLabel
lbl)       -> Platform -> CLabel -> CmmType
cmmLabelType Platform
platform CLabel
lbl
   (CmmLabelOff CLabel
lbl Int
_)  -> Platform -> CLabel -> CmmType
cmmLabelType Platform
platform CLabel
lbl
   (CmmLabelDiffOff CLabel
_ CLabel
_ Int
_ Width
width) -> Width -> CmmType
cmmBits Width
width
   (CmmBlock BlockId
_)         -> Platform -> CmmType
bWord Platform
platform
   (CmmLit
CmmHighStackMark)   -> Platform -> CmmType
bWord Platform
platform

cmmLabelType :: Platform -> CLabel -> CmmType
cmmLabelType :: Platform -> CLabel -> CmmType
cmmLabelType Platform
platform CLabel
lbl
 | CLabel -> Bool
isGcPtrLabel CLabel
lbl = Platform -> CmmType
gcWord Platform
platform
 | Bool
otherwise        = Platform -> CmmType
bWord Platform
platform

cmmExprWidth :: Platform -> CmmExpr -> Width
cmmExprWidth :: Platform -> CmmExpr -> Width
cmmExprWidth Platform
platform CmmExpr
e = CmmType -> Width
typeWidth (Platform -> CmmExpr -> CmmType
cmmExprType Platform
platform CmmExpr
e)

-- | Returns an alignment in bytes of a CmmExpr when it's a statically
-- known integer constant, otherwise returns an alignment of 1 byte.
-- The caller is responsible for using with a sensible CmmExpr
-- argument.
cmmExprAlignment :: CmmExpr -> Alignment
cmmExprAlignment :: CmmExpr -> Alignment
cmmExprAlignment (CmmLit (CmmInt Integer
intOff Width
_)) = Int -> Alignment
alignmentOf (Integer -> Int
forall a. Num a => Integer -> a
fromInteger Integer
intOff)
cmmExprAlignment CmmExpr
_                          = Int -> Alignment
mkAlignment Int
1
--------
--- Negation for conditional branches

maybeInvertCmmExpr :: CmmExpr -> Maybe CmmExpr
maybeInvertCmmExpr :: CmmExpr -> Maybe CmmExpr
maybeInvertCmmExpr (CmmMachOp MachOp
op [CmmExpr]
args) = do MachOp
op' <- MachOp -> Maybe MachOp
maybeInvertComparison MachOp
op
                                            CmmExpr -> Maybe CmmExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (MachOp -> [CmmExpr] -> CmmExpr
CmmMachOp MachOp
op' [CmmExpr]
args)
maybeInvertCmmExpr CmmExpr
_ = Maybe CmmExpr
forall a. Maybe a
Nothing

-----------------------------------------------------------------------------
--              Local registers
-----------------------------------------------------------------------------

data LocalReg
  = LocalReg {-# UNPACK #-} !Unique CmmType
    -- ^ Parameters:
    --   1. Identifier
    --   2. Type

instance Eq LocalReg where
  (LocalReg Unique
u1 CmmType
_) == :: LocalReg -> LocalReg -> Bool
== (LocalReg Unique
u2 CmmType
_) = Unique
u1 Unique -> Unique -> Bool
forall a. Eq a => a -> a -> Bool
== Unique
u2

-- This is non-deterministic but we do not currently support deterministic
-- code-generation. See Note [Unique Determinism and code generation]
-- See Note [No Ord for Unique]
instance Ord LocalReg where
  compare :: LocalReg -> LocalReg -> Ordering
compare (LocalReg Unique
u1 CmmType
_) (LocalReg Unique
u2 CmmType
_) = Unique -> Unique -> Ordering
nonDetCmpUnique Unique
u1 Unique
u2

instance Uniquable LocalReg where
  getUnique :: LocalReg -> Unique
getUnique (LocalReg Unique
uniq CmmType
_) = Unique
uniq

cmmRegType :: Platform -> CmmReg -> CmmType
cmmRegType :: Platform -> CmmReg -> CmmType
cmmRegType Platform
_        (CmmLocal  LocalReg
reg) = LocalReg -> CmmType
localRegType LocalReg
reg
cmmRegType Platform
platform (CmmGlobal GlobalReg
reg) = Platform -> GlobalReg -> CmmType
globalRegType Platform
platform GlobalReg
reg

cmmRegWidth :: Platform -> CmmReg -> Width
cmmRegWidth :: Platform -> CmmReg -> Width
cmmRegWidth Platform
platform = CmmType -> Width
typeWidth (CmmType -> Width) -> (CmmReg -> CmmType) -> CmmReg -> Width
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Platform -> CmmReg -> CmmType
cmmRegType Platform
platform

localRegType :: LocalReg -> CmmType
localRegType :: LocalReg -> CmmType
localRegType (LocalReg Unique
_ CmmType
rep) = CmmType
rep

-----------------------------------------------------------------------------
--    Register-use information for expressions and other types
-----------------------------------------------------------------------------

-- | Sets of registers

-- These are used for dataflow facts, and a common operation is taking
-- the union of two RegSets and then asking whether the union is the
-- same as one of the inputs.  UniqSet isn't good here, because
-- sizeUniqSet is O(n) whereas Set.size is O(1), so we use ordinary
-- Sets.

type RegSet r     = Set r
type LocalRegSet  = RegSet LocalReg
type GlobalRegSet = RegSet GlobalReg

emptyRegSet             :: RegSet r
nullRegSet              :: RegSet r -> Bool
elemRegSet              :: Ord r => r -> RegSet r -> Bool
extendRegSet            :: Ord r => RegSet r -> r -> RegSet r
deleteFromRegSet        :: Ord r => RegSet r -> r -> RegSet r
mkRegSet                :: Ord r => [r] -> RegSet r
minusRegSet, plusRegSet, timesRegSet :: Ord r => RegSet r -> RegSet r -> RegSet r
sizeRegSet              :: RegSet r -> Int
regSetToList            :: RegSet r -> [r]

emptyRegSet :: forall r. RegSet r
emptyRegSet      = Set r
forall r. RegSet r
Set.empty
nullRegSet :: forall r. RegSet r -> Bool
nullRegSet       = Set r -> Bool
forall r. RegSet r -> Bool
Set.null
elemRegSet :: forall r. Ord r => r -> RegSet r -> Bool
elemRegSet       = r -> Set r -> Bool
forall r. Ord r => r -> RegSet r -> Bool
Set.member
extendRegSet :: forall r. Ord r => RegSet r -> r -> RegSet r
extendRegSet     = (r -> Set r -> Set r) -> Set r -> r -> Set r
forall a b c. (a -> b -> c) -> b -> a -> c
flip r -> Set r -> Set r
forall a. Ord a => a -> Set a -> Set a
Set.insert
deleteFromRegSet :: forall r. Ord r => RegSet r -> r -> RegSet r
deleteFromRegSet = (r -> Set r -> Set r) -> Set r -> r -> Set r
forall a b c. (a -> b -> c) -> b -> a -> c
flip r -> Set r -> Set r
forall a. Ord a => a -> Set a -> Set a
Set.delete
mkRegSet :: forall r. Ord r => [r] -> RegSet r
mkRegSet         = [r] -> Set r
forall r. Ord r => [r] -> RegSet r
Set.fromList
minusRegSet :: forall r. Ord r => RegSet r -> RegSet r -> RegSet r
minusRegSet      = Set r -> Set r -> Set r
forall r. Ord r => RegSet r -> RegSet r -> RegSet r
Set.difference
plusRegSet :: forall r. Ord r => RegSet r -> RegSet r -> RegSet r
plusRegSet       = Set r -> Set r -> Set r
forall r. Ord r => RegSet r -> RegSet r -> RegSet r
Set.union
timesRegSet :: forall r. Ord r => RegSet r -> RegSet r -> RegSet r
timesRegSet      = Set r -> Set r -> Set r
forall r. Ord r => RegSet r -> RegSet r -> RegSet r
Set.intersection
sizeRegSet :: forall r. RegSet r -> Int
sizeRegSet       = Set r -> Int
forall r. RegSet r -> Int
Set.size
regSetToList :: forall r. RegSet r -> [r]
regSetToList     = Set r -> [r]
forall r. RegSet r -> [r]
Set.toList

class Ord r => UserOfRegs r a where
  foldRegsUsed :: DynFlags -> (b -> r -> b) -> b -> a -> b

foldLocalRegsUsed :: UserOfRegs LocalReg a
                  => DynFlags -> (b -> LocalReg -> b) -> b -> a -> b
foldLocalRegsUsed :: forall a b.
UserOfRegs LocalReg a =>
DynFlags -> (b -> LocalReg -> b) -> b -> a -> b
foldLocalRegsUsed = DynFlags -> (b -> LocalReg -> b) -> b -> a -> b
forall r a b.
UserOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsUsed

class Ord r => DefinerOfRegs r a where
  foldRegsDefd :: DynFlags -> (b -> r -> b) -> b -> a -> b

foldLocalRegsDefd :: DefinerOfRegs LocalReg a
                  => DynFlags -> (b -> LocalReg -> b) -> b -> a -> b
foldLocalRegsDefd :: forall a b.
DefinerOfRegs LocalReg a =>
DynFlags -> (b -> LocalReg -> b) -> b -> a -> b
foldLocalRegsDefd = DynFlags -> (b -> LocalReg -> b) -> b -> a -> b
forall r a b.
DefinerOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsDefd

instance UserOfRegs LocalReg CmmReg where
    foldRegsUsed :: forall b. DynFlags -> (b -> LocalReg -> b) -> b -> CmmReg -> b
foldRegsUsed DynFlags
_ b -> LocalReg -> b
f b
z (CmmLocal LocalReg
reg) = b -> LocalReg -> b
f b
z LocalReg
reg
    foldRegsUsed DynFlags
_ b -> LocalReg -> b
_ b
z (CmmGlobal GlobalReg
_)  = b
z

instance DefinerOfRegs LocalReg CmmReg where
    foldRegsDefd :: forall b. DynFlags -> (b -> LocalReg -> b) -> b -> CmmReg -> b
foldRegsDefd DynFlags
_ b -> LocalReg -> b
f b
z (CmmLocal LocalReg
reg) = b -> LocalReg -> b
f b
z LocalReg
reg
    foldRegsDefd DynFlags
_ b -> LocalReg -> b
_ b
z (CmmGlobal GlobalReg
_)  = b
z

instance UserOfRegs GlobalReg CmmReg where
    foldRegsUsed :: forall b. DynFlags -> (b -> GlobalReg -> b) -> b -> CmmReg -> b
foldRegsUsed DynFlags
_ b -> GlobalReg -> b
_ b
z (CmmLocal LocalReg
_)    = b
z
    foldRegsUsed DynFlags
_ b -> GlobalReg -> b
f b
z (CmmGlobal GlobalReg
reg) = b -> GlobalReg -> b
f b
z GlobalReg
reg

instance DefinerOfRegs GlobalReg CmmReg where
    foldRegsDefd :: forall b. DynFlags -> (b -> GlobalReg -> b) -> b -> CmmReg -> b
foldRegsDefd DynFlags
_ b -> GlobalReg -> b
_ b
z (CmmLocal LocalReg
_)    = b
z
    foldRegsDefd DynFlags
_ b -> GlobalReg -> b
f b
z (CmmGlobal GlobalReg
reg) = b -> GlobalReg -> b
f b
z GlobalReg
reg

instance Ord r => UserOfRegs r r where
    foldRegsUsed :: forall b. DynFlags -> (b -> r -> b) -> b -> r -> b
foldRegsUsed DynFlags
_ b -> r -> b
f b
z r
r = b -> r -> b
f b
z r
r

instance Ord r => DefinerOfRegs r r where
    foldRegsDefd :: forall b. DynFlags -> (b -> r -> b) -> b -> r -> b
foldRegsDefd DynFlags
_ b -> r -> b
f b
z r
r = b -> r -> b
f b
z r
r

instance (Ord r, UserOfRegs r CmmReg) => UserOfRegs r CmmExpr where
  -- The (Ord r) in the context is necessary here
  -- See Note [Recursive superclasses] in GHC.Tc.TyCl.Instance
  foldRegsUsed :: forall b. DynFlags -> (b -> r -> b) -> b -> CmmExpr -> b
foldRegsUsed DynFlags
dflags b -> r -> b
f !b
z CmmExpr
e = b -> CmmExpr -> b
expr b
z CmmExpr
e
    where expr :: b -> CmmExpr -> b
expr b
z (CmmLit CmmLit
_)          = b
z
          expr b
z (CmmLoad CmmExpr
addr CmmType
_)    = DynFlags -> (b -> r -> b) -> b -> CmmExpr -> b
forall r a b.
UserOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsUsed DynFlags
dflags b -> r -> b
f b
z CmmExpr
addr
          expr b
z (CmmReg CmmReg
r)          = DynFlags -> (b -> r -> b) -> b -> CmmReg -> b
forall r a b.
UserOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsUsed DynFlags
dflags b -> r -> b
f b
z CmmReg
r
          expr b
z (CmmMachOp MachOp
_ [CmmExpr]
exprs) = DynFlags -> (b -> r -> b) -> b -> [CmmExpr] -> b
forall r a b.
UserOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsUsed DynFlags
dflags b -> r -> b
f b
z [CmmExpr]
exprs
          expr b
z (CmmRegOff CmmReg
r Int
_)     = DynFlags -> (b -> r -> b) -> b -> CmmReg -> b
forall r a b.
UserOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsUsed DynFlags
dflags b -> r -> b
f b
z CmmReg
r
          expr b
z (CmmStackSlot Area
_ Int
_)  = b
z

instance UserOfRegs r a => UserOfRegs r [a] where
  foldRegsUsed :: forall b. DynFlags -> (b -> r -> b) -> b -> [a] -> b
foldRegsUsed DynFlags
dflags b -> r -> b
f b
set [a]
as = (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (DynFlags -> (b -> r -> b) -> b -> a -> b
forall r a b.
UserOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsUsed DynFlags
dflags b -> r -> b
f) b
set [a]
as
  {-# INLINABLE foldRegsUsed #-}

instance DefinerOfRegs r a => DefinerOfRegs r [a] where
  foldRegsDefd :: forall b. DynFlags -> (b -> r -> b) -> b -> [a] -> b
foldRegsDefd DynFlags
dflags b -> r -> b
f b
set [a]
as = (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (DynFlags -> (b -> r -> b) -> b -> a -> b
forall r a b.
DefinerOfRegs r a =>
DynFlags -> (b -> r -> b) -> b -> a -> b
foldRegsDefd DynFlags
dflags b -> r -> b
f) b
set [a]
as
  {-# INLINABLE foldRegsDefd #-}

-----------------------------------------------------------------------------
--              Global STG registers
-----------------------------------------------------------------------------

data VGcPtr = VGcPtr | VNonGcPtr deriving( VGcPtr -> VGcPtr -> Bool
(VGcPtr -> VGcPtr -> Bool)
-> (VGcPtr -> VGcPtr -> Bool) -> Eq VGcPtr
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: VGcPtr -> VGcPtr -> Bool
$c/= :: VGcPtr -> VGcPtr -> Bool
== :: VGcPtr -> VGcPtr -> Bool
$c== :: VGcPtr -> VGcPtr -> Bool
Eq, Int -> VGcPtr -> ShowS
[VGcPtr] -> ShowS
VGcPtr -> String
(Int -> VGcPtr -> ShowS)
-> (VGcPtr -> String) -> ([VGcPtr] -> ShowS) -> Show VGcPtr
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [VGcPtr] -> ShowS
$cshowList :: [VGcPtr] -> ShowS
show :: VGcPtr -> String
$cshow :: VGcPtr -> String
showsPrec :: Int -> VGcPtr -> ShowS
$cshowsPrec :: Int -> VGcPtr -> ShowS
Show )

-----------------------------------------------------------------------------
--              Global STG registers
-----------------------------------------------------------------------------
{-
Note [Overlapping global registers]

The backend might not faithfully implement the abstraction of the STG
machine with independent registers for different values of type
GlobalReg. Specifically, certain pairs of registers (r1, r2) may
overlap in the sense that a store to r1 invalidates the value in r2,
and vice versa.

Currently this occurs only on the x86_64 architecture where FloatReg n
and DoubleReg n are assigned the same microarchitectural register, in
order to allow functions to receive more Float# or Double# arguments
in registers (as opposed to on the stack).

There are no specific rules about which registers might overlap with
which other registers, but presumably it's safe to assume that nothing
will overlap with special registers like Sp or BaseReg.

Use GHC.Cmm.Utils.regsOverlap to determine whether two GlobalRegs overlap
on a particular platform. The instance Eq GlobalReg is syntactic
equality of STG registers and does not take overlap into
account. However it is still used in UserOfRegs/DefinerOfRegs and
there are likely still bugs there, beware!
-}

data GlobalReg
  -- Argument and return registers
  = VanillaReg                  -- pointers, unboxed ints and chars
        {-# UNPACK #-} !Int     -- its number
        VGcPtr

  | FloatReg            -- single-precision floating-point registers
        {-# UNPACK #-} !Int     -- its number

  | DoubleReg           -- double-precision floating-point registers
        {-# UNPACK #-} !Int     -- its number

  | LongReg             -- long int registers (64-bit, really)
        {-# UNPACK #-} !Int     -- its number

  | XmmReg                      -- 128-bit SIMD vector register
        {-# UNPACK #-} !Int     -- its number

  | YmmReg                      -- 256-bit SIMD vector register
        {-# UNPACK #-} !Int     -- its number

  | ZmmReg                      -- 512-bit SIMD vector register
        {-# UNPACK #-} !Int     -- its number

  -- STG registers
  | Sp                  -- Stack ptr; points to last occupied stack location.
  | SpLim               -- Stack limit
  | Hp                  -- Heap ptr; points to last occupied heap location.
  | HpLim               -- Heap limit register
  | CCCS                -- Current cost-centre stack
  | CurrentTSO          -- pointer to current thread's TSO
  | CurrentNursery      -- pointer to allocation area
  | HpAlloc             -- allocation count for heap check failure

                -- We keep the address of some commonly-called
                -- functions in the register table, to keep code
                -- size down:
  | EagerBlackholeInfo  -- stg_EAGER_BLACKHOLE_info
  | GCEnter1            -- stg_gc_enter_1
  | GCFun               -- stg_gc_fun

  -- Base offset for the register table, used for accessing registers
  -- which do not have real registers assigned to them.  This register
  -- will only appear after we have expanded GlobalReg into memory accesses
  -- (where necessary) in the native code generator.
  | BaseReg

  -- The register used by the platform for the C stack pointer. This is
  -- a break in the STG abstraction used exclusively to setup stack unwinding
  -- information.
  | MachSp

  -- The is a dummy register used to indicate to the stack unwinder where
  -- a routine would return to.
  | UnwindReturnReg

  -- Base Register for PIC (position-independent code) calculations
  -- Only used inside the native code generator. It's exact meaning differs
  -- from platform to platform (see module PositionIndependentCode).
  | PicBaseReg

  deriving( Int -> GlobalReg -> ShowS
[GlobalReg] -> ShowS
GlobalReg -> String
(Int -> GlobalReg -> ShowS)
-> (GlobalReg -> String)
-> ([GlobalReg] -> ShowS)
-> Show GlobalReg
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [GlobalReg] -> ShowS
$cshowList :: [GlobalReg] -> ShowS
show :: GlobalReg -> String
$cshow :: GlobalReg -> String
showsPrec :: Int -> GlobalReg -> ShowS
$cshowsPrec :: Int -> GlobalReg -> ShowS
Show )

instance Eq GlobalReg where
   VanillaReg Int
i VGcPtr
_ == :: GlobalReg -> GlobalReg -> Bool
== VanillaReg Int
j VGcPtr
_ = Int
iInt -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
j -- Ignore type when seeking clashes
   FloatReg Int
i == FloatReg Int
j = Int
iInt -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
j
   DoubleReg Int
i == DoubleReg Int
j = Int
iInt -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
j
   LongReg Int
i == LongReg Int
j = Int
iInt -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
j
   -- NOTE: XMM, YMM, ZMM registers actually are the same registers
   -- at least with respect to store at YMM i and then read from XMM i
   -- and similarly for ZMM etc.
   XmmReg Int
i == XmmReg Int
j = Int
iInt -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
j
   YmmReg Int
i == YmmReg Int
j = Int
iInt -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
j
   ZmmReg Int
i == ZmmReg Int
j = Int
iInt -> Int -> Bool
forall a. Eq a => a -> a -> Bool
==Int
j
   GlobalReg
Sp == GlobalReg
Sp = Bool
True
   GlobalReg
SpLim == GlobalReg
SpLim = Bool
True
   GlobalReg
Hp == GlobalReg
Hp = Bool
True
   GlobalReg
HpLim == GlobalReg
HpLim = Bool
True
   GlobalReg
CCCS == GlobalReg
CCCS = Bool
True
   GlobalReg
CurrentTSO == GlobalReg
CurrentTSO = Bool
True
   GlobalReg
CurrentNursery == GlobalReg
CurrentNursery = Bool
True
   GlobalReg
HpAlloc == GlobalReg
HpAlloc = Bool
True
   GlobalReg
EagerBlackholeInfo == GlobalReg
EagerBlackholeInfo = Bool
True
   GlobalReg
GCEnter1 == GlobalReg
GCEnter1 = Bool
True
   GlobalReg
GCFun == GlobalReg
GCFun = Bool
True
   GlobalReg
BaseReg == GlobalReg
BaseReg = Bool
True
   GlobalReg
MachSp == GlobalReg
MachSp = Bool
True
   GlobalReg
UnwindReturnReg == GlobalReg
UnwindReturnReg = Bool
True
   GlobalReg
PicBaseReg == GlobalReg
PicBaseReg = Bool
True
   GlobalReg
_r1 == GlobalReg
_r2 = Bool
False

instance Ord GlobalReg where
   compare :: GlobalReg -> GlobalReg -> Ordering
compare (VanillaReg Int
i VGcPtr
_) (VanillaReg Int
j VGcPtr
_) = Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
compare Int
i Int
j
     -- Ignore type when seeking clashes
   compare (FloatReg Int
i)  (FloatReg  Int
j) = Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
compare Int
i Int
j
   compare (DoubleReg Int
i) (DoubleReg Int
j) = Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
compare Int
i Int
j
   compare (LongReg Int
i)   (LongReg   Int
j) = Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
compare Int
i Int
j
   compare (XmmReg Int
i)    (XmmReg    Int
j) = Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
compare Int
i Int
j
   compare (YmmReg Int
i)    (YmmReg    Int
j) = Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
compare Int
i Int
j
   compare (ZmmReg Int
i)    (ZmmReg    Int
j) = Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
compare Int
i Int
j
   compare GlobalReg
Sp GlobalReg
Sp = Ordering
EQ
   compare GlobalReg
SpLim GlobalReg
SpLim = Ordering
EQ
   compare GlobalReg
Hp GlobalReg
Hp = Ordering
EQ
   compare GlobalReg
HpLim GlobalReg
HpLim = Ordering
EQ
   compare GlobalReg
CCCS GlobalReg
CCCS = Ordering
EQ
   compare GlobalReg
CurrentTSO GlobalReg
CurrentTSO = Ordering
EQ
   compare GlobalReg
CurrentNursery GlobalReg
CurrentNursery = Ordering
EQ
   compare GlobalReg
HpAlloc GlobalReg
HpAlloc = Ordering
EQ
   compare GlobalReg
EagerBlackholeInfo GlobalReg
EagerBlackholeInfo = Ordering
EQ
   compare GlobalReg
GCEnter1 GlobalReg
GCEnter1 = Ordering
EQ
   compare GlobalReg
GCFun GlobalReg
GCFun = Ordering
EQ
   compare GlobalReg
BaseReg GlobalReg
BaseReg = Ordering
EQ
   compare GlobalReg
MachSp GlobalReg
MachSp = Ordering
EQ
   compare GlobalReg
UnwindReturnReg GlobalReg
UnwindReturnReg = Ordering
EQ
   compare GlobalReg
PicBaseReg GlobalReg
PicBaseReg = Ordering
EQ
   compare (VanillaReg Int
_ VGcPtr
_) GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ (VanillaReg Int
_ VGcPtr
_) = Ordering
GT
   compare (FloatReg Int
_) GlobalReg
_     = Ordering
LT
   compare GlobalReg
_ (FloatReg Int
_)     = Ordering
GT
   compare (DoubleReg Int
_) GlobalReg
_    = Ordering
LT
   compare GlobalReg
_ (DoubleReg Int
_)    = Ordering
GT
   compare (LongReg Int
_) GlobalReg
_      = Ordering
LT
   compare GlobalReg
_ (LongReg Int
_)      = Ordering
GT
   compare (XmmReg Int
_) GlobalReg
_       = Ordering
LT
   compare GlobalReg
_ (XmmReg Int
_)       = Ordering
GT
   compare (YmmReg Int
_) GlobalReg
_       = Ordering
LT
   compare GlobalReg
_ (YmmReg Int
_)       = Ordering
GT
   compare (ZmmReg Int
_) GlobalReg
_       = Ordering
LT
   compare GlobalReg
_ (ZmmReg Int
_)       = Ordering
GT
   compare GlobalReg
Sp GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
Sp = Ordering
GT
   compare GlobalReg
SpLim GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
SpLim = Ordering
GT
   compare GlobalReg
Hp GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
Hp = Ordering
GT
   compare GlobalReg
HpLim GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
HpLim = Ordering
GT
   compare GlobalReg
CCCS GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
CCCS = Ordering
GT
   compare GlobalReg
CurrentTSO GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
CurrentTSO = Ordering
GT
   compare GlobalReg
CurrentNursery GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
CurrentNursery = Ordering
GT
   compare GlobalReg
HpAlloc GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
HpAlloc = Ordering
GT
   compare GlobalReg
GCEnter1 GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
GCEnter1 = Ordering
GT
   compare GlobalReg
GCFun GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
GCFun = Ordering
GT
   compare GlobalReg
BaseReg GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
BaseReg = Ordering
GT
   compare GlobalReg
MachSp GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
MachSp = Ordering
GT
   compare GlobalReg
UnwindReturnReg GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
UnwindReturnReg = Ordering
GT
   compare GlobalReg
EagerBlackholeInfo GlobalReg
_ = Ordering
LT
   compare GlobalReg
_ GlobalReg
EagerBlackholeInfo = Ordering
GT

-- convenient aliases
baseReg, spReg, hpReg, spLimReg, hpLimReg, nodeReg,
  currentTSOReg, currentNurseryReg, hpAllocReg, cccsReg  :: CmmReg
baseReg :: CmmReg
baseReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
BaseReg
spReg :: CmmReg
spReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
Sp
hpReg :: CmmReg
hpReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
Hp
hpLimReg :: CmmReg
hpLimReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
HpLim
spLimReg :: CmmReg
spLimReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
SpLim
nodeReg :: CmmReg
nodeReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
node
currentTSOReg :: CmmReg
currentTSOReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
CurrentTSO
currentNurseryReg :: CmmReg
currentNurseryReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
CurrentNursery
hpAllocReg :: CmmReg
hpAllocReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
HpAlloc
cccsReg :: CmmReg
cccsReg = GlobalReg -> CmmReg
CmmGlobal GlobalReg
CCCS

node :: GlobalReg
node :: GlobalReg
node = Int -> VGcPtr -> GlobalReg
VanillaReg Int
1 VGcPtr
VGcPtr

globalRegType :: Platform -> GlobalReg -> CmmType
globalRegType :: Platform -> GlobalReg -> CmmType
globalRegType Platform
platform = \case
   (VanillaReg Int
_ VGcPtr
VGcPtr)    -> Platform -> CmmType
gcWord Platform
platform
   (VanillaReg Int
_ VGcPtr
VNonGcPtr) -> Platform -> CmmType
bWord Platform
platform
   (FloatReg Int
_)             -> Width -> CmmType
cmmFloat Width
W32
   (DoubleReg Int
_)            -> Width -> CmmType
cmmFloat Width
W64
   (LongReg Int
_)              -> Width -> CmmType
cmmBits Width
W64
   -- TODO: improve the internal model of SIMD/vectorized registers
   -- the right design SHOULd improve handling of float and double code too.
   -- see remarks in "NOTE [SIMD Design for the future]"" in GHC.StgToCmm.Prim
   (XmmReg Int
_) -> Int -> CmmType -> CmmType
cmmVec Int
4 (Width -> CmmType
cmmBits Width
W32)
   (YmmReg Int
_) -> Int -> CmmType -> CmmType
cmmVec Int
8 (Width -> CmmType
cmmBits Width
W32)
   (ZmmReg Int
_) -> Int -> CmmType -> CmmType
cmmVec Int
16 (Width -> CmmType
cmmBits Width
W32)

   GlobalReg
Hp         -> Platform -> CmmType
gcWord Platform
platform -- The initialiser for all
                                 -- dynamically allocated closures
   GlobalReg
_          -> Platform -> CmmType
bWord Platform
platform

isArgReg :: GlobalReg -> Bool
isArgReg :: GlobalReg -> Bool
isArgReg (VanillaReg {}) = Bool
True
isArgReg (FloatReg {})   = Bool
True
isArgReg (DoubleReg {})  = Bool
True
isArgReg (LongReg {})    = Bool
True
isArgReg (XmmReg {})     = Bool
True
isArgReg (YmmReg {})     = Bool
True
isArgReg (ZmmReg {})     = Bool
True
isArgReg GlobalReg
_               = Bool
False