RegClass(..), regClass,
Reg(..), isRealReg, isVirtualReg,
- allocatableRegs,
+ allocatableRegs, argRegs, allArgRegs, callClobberedRegs,
Imm(..),
MachRegsAddr(..),
#if sparc_TARGET_ARCH
, fits13Bits
, fpRel, gReg, iReg, lReg, oReg, largeOffsetError
- , fp, g0, o0, f0
+ , fp, sp, g0, g1, g2, o0, f0, f6, f8, f26, f27
#endif
) where
getUniqueNat, returnNat, thenNat, NatM )
import Unique ( mkPseudoUnique2, Uniquable(..), Unique )
import Outputable
+import FastTypes
\end{code}
% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-- Bool==True ==> in a different DLL
| ImmLit SDoc -- Simple string
| ImmIndex CLabel Int
+ | ImmFloat Rational
| ImmDouble Rational
IF_ARCH_sparc(
| LO Imm -- Possible restrictions...
#endif
#if sparc_TARGET_ARCH
-{-# SPECIALIZE
- fits13Bits :: Int -> Bool
- #-}
-{-# SPECIALIZE
- fits13Bits :: Integer -> Bool
- #-}
+{-# SPECIALIZE fits13Bits :: Int -> Bool, Integer -> Bool #-}
fits13Bits :: Integral a => a -> Bool
fits13Bits x = x >= -4096 && x < 4096
data RegClass
= RcInteger
- | RcFloating
+ | RcFloat
+ | RcDouble
deriving Eq
data Reg
= RealReg Int
| VirtualRegI Unique
| VirtualRegF Unique
+ | VirtualRegD Unique
+
+unRealReg (RealReg i) = i
+unRealReg vreg = pprPanic "unRealReg on VirtualReg" (ppr vreg)
mkVReg :: Unique -> PrimRep -> Reg
mkVReg u pk
- = if isFloatingRep pk then VirtualRegF u else VirtualRegI u
+#if sparc_TARGET_ARCH
+ = case pk of
+ FloatRep -> VirtualRegF u
+ DoubleRep -> VirtualRegD u
+ other -> VirtualRegI u
+#else
+ = if isFloatingRep pk then VirtualRegD u else VirtualRegI u
+#endif
isVirtualReg (RealReg _) = False
isVirtualReg (VirtualRegI _) = True
isVirtualReg (VirtualRegF _) = True
+isVirtualReg (VirtualRegD _) = True
isRealReg = not . isVirtualReg
getNewRegNCG :: PrimRep -> NatM Reg
getNewRegNCG pk
- = if isFloatingRep pk
- then getUniqueNat `thenNat` \ u -> returnNat (VirtualRegF u)
- else getUniqueNat `thenNat` \ u -> returnNat (VirtualRegI u)
+ = getUniqueNat `thenNat` \ u -> returnNat (mkVReg u pk)
instance Eq Reg where
(==) (RealReg i1) (RealReg i2) = i1 == i2
(==) (VirtualRegI u1) (VirtualRegI u2) = u1 == u2
(==) (VirtualRegF u1) (VirtualRegF u2) = u1 == u2
+ (==) (VirtualRegD u1) (VirtualRegD u2) = u1 == u2
(==) reg1 reg2 = False
instance Ord Reg where
compare (RealReg i1) (RealReg i2) = compare i1 i2
compare (RealReg _) (VirtualRegI _) = LT
compare (RealReg _) (VirtualRegF _) = LT
+ compare (RealReg _) (VirtualRegD _) = LT
+
compare (VirtualRegI _) (RealReg _) = GT
compare (VirtualRegI u1) (VirtualRegI u2) = compare u1 u2
compare (VirtualRegI _) (VirtualRegF _) = LT
+ compare (VirtualRegI _) (VirtualRegD _) = LT
+
compare (VirtualRegF _) (RealReg _) = GT
compare (VirtualRegF _) (VirtualRegI _) = GT
compare (VirtualRegF u1) (VirtualRegF u2) = compare u1 u2
+ compare (VirtualRegF _) (VirtualRegD _) = LT
+
+ compare (VirtualRegD _) (RealReg _) = GT
+ compare (VirtualRegD _) (VirtualRegI _) = GT
+ compare (VirtualRegD _) (VirtualRegF _) = GT
+ compare (VirtualRegD u1) (VirtualRegD u2) = compare u1 u2
+
instance Show Reg where
showsPrec _ (RealReg i) = showString (showReg i)
showsPrec _ (VirtualRegI u) = showString "%vI_" . shows u
showsPrec _ (VirtualRegF u) = showString "%vF_" . shows u
+ showsPrec _ (VirtualRegD u) = showString "%vD_" . shows u
instance Outputable Reg where
ppr r = text (show r)
getUnique (RealReg i) = mkPseudoUnique2 i
getUnique (VirtualRegI u) = u
getUnique (VirtualRegF u) = u
+ getUnique (VirtualRegD u) = u
\end{code}
** Machine-specific Reg stuff: **
fp registers, and 3-operand insns for them, and we translate this into
real stack-based x86 fp code after register allocation.
+The fp registers are all Double registers; we don't have any RcFloat class
+regs. @regClass@ barfs if you give it a VirtualRegF, and mkVReg above should
+never generate them.
+
\begin{code}
#if i386_TARGET_ARCH
fake4 = RealReg 12
fake5 = RealReg 13
-regClass (RealReg i) = if i < 8 then RcInteger else RcFloating
+regClass (RealReg i) = if i < 8 then RcInteger else RcDouble
regClass (VirtualRegI u) = RcInteger
-regClass (VirtualRegF u) = RcFloating
+regClass (VirtualRegD u) = RcDouble
+regClass (VirtualRegF u) = pprPanic "regClass(x86):VirtualRegF"
+ (ppr (VirtualRegF u))
regNames
= ["%eax", "%ebx", "%ecx", "%edx", "%esi", "%edi", "%ebp", "%esp",
The SPARC has 64 registers of interest; 32 integer registers and 32
floating point registers. The mapping of STG registers to SPARC
machine registers is defined in StgRegs.h. We are, of course,
-prepared for any eventuality. When (if?) the sparc nativegen is
-ever revived, we should just treat it as if it has 16 floating
-regs, and use them in pairs.
+prepared for any eventuality.
+
+The whole fp-register pairing thing on sparcs is a huge nuisance. See
+fptools/ghc/includes/MachRegs.h for a description of what's going on
+here.
\begin{code}
#if sparc_TARGET_ARCH
iReg x = (24 + x)
fReg x = (32 + x)
--- CHECK THIS
-regClass (RealReg i) = if i < 32 then RcInteger else RcFloating
+nCG_FirstFloatReg :: Int
+nCG_FirstFloatReg = unRealReg NCG_FirstFloatReg
+
regClass (VirtualRegI u) = RcInteger
-regClass (VirtualRegF u) = RcFloating
+regClass (VirtualRegF u) = RcFloat
+regClass (VirtualRegD u) = RcDouble
+regClass (RealReg i) | i < 32 = RcInteger
+ | i < nCG_FirstFloatReg = RcDouble
+ | otherwise = RcFloat
--- FIX THIS
showReg :: Int -> String
showReg n
- = if n >= 0 && n < 64
- then "%sparc_real_reg_" ++ show n
- else "%unknown_sparc_real_reg_" ++ show n
+ | n >= 0 && n < 8 = "%g" ++ show n
+ | n >= 8 && n < 16 = "%o" ++ show (n-8)
+ | n >= 16 && n < 24 = "%l" ++ show (n-16)
+ | n >= 24 && n < 32 = "%i" ++ show (n-24)
+ | n >= 32 && n < 64 = "%f" ++ show (n-32)
+ | otherwise = "%unknown_sparc_real_reg_" ++ show n
+
+g0, g1, g2, fp, sp, o0, f0, f1, f6, f8, f22, f26, f27 :: Reg
+
+f6 = RealReg (fReg 6)
+f8 = RealReg (fReg 8)
+f22 = RealReg (fReg 22)
+f26 = RealReg (fReg 26)
+f27 = RealReg (fReg 27)
-g0, fp, sp, o0, f0 :: Reg
-g0 = RealReg (gReg 0)
-fp = RealReg (iReg 6)
-sp = RealReg (oReg 6)
-o0 = RealReg (oReg 0)
-f0 = RealReg (fReg 0)
+
+-- g0 is useful for codegen; is always zero, and writes to it vanish.
+g0 = RealReg (gReg 0)
+g1 = RealReg (gReg 1)
+g2 = RealReg (gReg 2)
+
+-- FP, SP, int and float return (from C) regs.
+fp = RealReg (iReg 6)
+sp = RealReg (oReg 6)
+o0 = RealReg (oReg 0)
+f0 = RealReg (fReg 0)
+f1 = RealReg (fReg 1)
#endif
\end{code}
#define i5 29
#define i6 30
#define i7 31
-#define f0 32
-#define f1 33
-#define f2 34
-#define f3 35
-#define f4 36
-#define f5 37
-#define f6 38
-#define f7 39
-#define f8 40
-#define f9 41
+
+#define f0 32
+#define f1 33
+#define f2 34
+#define f3 35
+#define f4 36
+#define f5 37
+#define f6 38
+#define f7 39
+#define f8 40
+#define f9 41
#define f10 42
#define f11 43
#define f12 44
#define f29 61
#define f30 62
#define f31 63
+
#endif
\end{code}
\begin{code}
baseRegOffset :: MagicId -> Int
-baseRegOffset (VanillaReg _ ILIT(1)) = OFFSET_R1
-baseRegOffset (VanillaReg _ ILIT(2)) = OFFSET_R2
-baseRegOffset (VanillaReg _ ILIT(3)) = OFFSET_R3
-baseRegOffset (VanillaReg _ ILIT(4)) = OFFSET_R4
-baseRegOffset (VanillaReg _ ILIT(5)) = OFFSET_R5
-baseRegOffset (VanillaReg _ ILIT(6)) = OFFSET_R6
-baseRegOffset (VanillaReg _ ILIT(7)) = OFFSET_R7
-baseRegOffset (VanillaReg _ ILIT(8)) = OFFSET_R8
-baseRegOffset (VanillaReg _ ILIT(9)) = OFFSET_R9
-baseRegOffset (VanillaReg _ ILIT(10)) = OFFSET_R10
-baseRegOffset (FloatReg ILIT(1)) = OFFSET_F1
-baseRegOffset (FloatReg ILIT(2)) = OFFSET_F2
-baseRegOffset (FloatReg ILIT(3)) = OFFSET_F3
-baseRegOffset (FloatReg ILIT(4)) = OFFSET_F4
-baseRegOffset (DoubleReg ILIT(1)) = OFFSET_D1
-baseRegOffset (DoubleReg ILIT(2)) = OFFSET_D2
+baseRegOffset (VanillaReg _ 1#) = OFFSET_R1
+baseRegOffset (VanillaReg _ 2#) = OFFSET_R2
+baseRegOffset (VanillaReg _ 3#) = OFFSET_R3
+baseRegOffset (VanillaReg _ 4#) = OFFSET_R4
+baseRegOffset (VanillaReg _ 5#) = OFFSET_R5
+baseRegOffset (VanillaReg _ 6#) = OFFSET_R6
+baseRegOffset (VanillaReg _ 7#) = OFFSET_R7
+baseRegOffset (VanillaReg _ 8#) = OFFSET_R8
+baseRegOffset (VanillaReg _ 9#) = OFFSET_R9
+baseRegOffset (VanillaReg _ 10#) = OFFSET_R10
+baseRegOffset (FloatReg 1#) = OFFSET_F1
+baseRegOffset (FloatReg 2#) = OFFSET_F2
+baseRegOffset (FloatReg 3#) = OFFSET_F3
+baseRegOffset (FloatReg 4#) = OFFSET_F4
+baseRegOffset (DoubleReg 1#) = OFFSET_D1
+baseRegOffset (DoubleReg 2#) = OFFSET_D2
baseRegOffset Sp = OFFSET_Sp
baseRegOffset Su = OFFSET_Su
baseRegOffset SpLim = OFFSET_SpLim
#ifdef OFFSET_Lng1
-baseRegOffset (LongReg _ ILIT(1)) = OFFSET_Lng1
+baseRegOffset (LongReg _ 1)) = OFFSET_Lng1
#endif
#ifdef OFFSET_Lng2
-baseRegOffset (LongReg _ ILIT(2)) = OFFSET_Lng2
+baseRegOffset (LongReg _ 2)) = OFFSET_Lng2
#endif
baseRegOffset Hp = OFFSET_Hp
baseRegOffset HpLim = OFFSET_HpLim
baseRegOffset CurrentTSO = OFFSET_CurrentTSO
baseRegOffset CurrentNursery = OFFSET_CurrentNursery
-#ifdef DEBUG
+#ifdef NCG_DEBUG
baseRegOffset BaseReg = panic "baseRegOffset:BaseReg"
baseRegOffset CurCostCentre = panic "baseRegOffset:CurCostCentre"
baseRegOffset VoidReg = panic "baseRegOffset:VoidReg"
magicIdRegMaybe BaseReg = Just (RealReg REG_Base)
#endif
#ifdef REG_R1
-magicIdRegMaybe (VanillaReg _ ILIT(1)) = Just (RealReg REG_R1)
+magicIdRegMaybe (VanillaReg _ 1#) = Just (RealReg REG_R1)
#endif
#ifdef REG_R2
magicIdRegMaybe (VanillaReg _ ILIT(2)) = Just (RealReg REG_R2)
\begin{code}
-------------------------------
-#if 0
-freeRegs :: [Reg]
-freeRegs
- = freeMappedRegs IF_ARCH_alpha( [0..63],
- IF_ARCH_i386( [0..13],
- IF_ARCH_sparc( [0..63],)))
-#endif
-- allMachRegs is the complete set of machine regs.
allMachRegNos :: [Int]
allMachRegNos
= IF_ARCH_alpha( [0..63],
IF_ARCH_i386( [0..13],
- IF_ARCH_sparc( [0..63],)))
+ IF_ARCH_sparc( ([0..31]
+ ++ [f0,f2 .. nCG_FirstFloatReg-1]
+ ++ [nCG_FirstFloatReg .. f31]),
+ )))
-- allocatableRegs is allMachRegNos with the fixed-use regs removed.
+-- i.e., these are the regs for which we are prepared to allow the
+-- register allocator to attempt to map VRegs to.
allocatableRegs :: [Reg]
allocatableRegs
- = let isFree (RealReg (I# i)) = _IS_TRUE_(freeReg i)
- in filter isFree (map RealReg allMachRegNos)
-
+ = let isFree i = _IS_TRUE_(freeReg i)
+ in map RealReg (filter isFree allMachRegNos)
-------------------------------
-#if 0
+-- these are the regs which we cannot assume stay alive over a
+-- C call.
callClobberedRegs :: [Reg]
callClobberedRegs
- = freeMappedRegs
+ =
#if alpha_TARGET_ARCH
[0, 1, 2, 3, 4, 5, 6, 7, 8,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
fReg 24, fReg 25, fReg 26, fReg 27, fReg 28, fReg 29, fReg 30]
#endif {- alpha_TARGET_ARCH -}
#if i386_TARGET_ARCH
- [{-none-}]
+ -- caller-saves registers
+ map RealReg [eax,ecx,edx,fake0,fake1,fake2,fake3,fake4,fake5]
#endif {- i386_TARGET_ARCH -}
#if sparc_TARGET_ARCH
- ( oReg 7 :
- [oReg i | i <- [0..5]] ++
- [gReg i | i <- [1..7]] ++
- [fReg i | i <- [0..31]] )
+ map RealReg
+ ( oReg 7 :
+ [oReg i | i <- [0..5]] ++
+ [gReg i | i <- [1..7]] ++
+ [fReg i | i <- [0..31]] )
#endif {- sparc_TARGET_ARCH -}
-#endif
-------------------------------
-#if 0
+-- argRegs is the set of regs which are read for an n-argument call to C.
+-- For archs which pass all args on the stack (x86), is empty.
+-- Sparc passes up to the first 6 args in regs.
+-- Dunno about Alpha.
argRegs :: Int -> [Reg]
-argRegs 0 = []
#if i386_TARGET_ARCH
-argRegs _ = panic "MachRegs.argRegs: doesn't work on I386"
-#else
+argRegs _ = panic "MachRegs.argRegs(x86): should not be used!"
+#endif
+
#if alpha_TARGET_ARCH
+argRegs 0 = []
argRegs 1 = freeMappedRegs [16, fReg 16]
argRegs 2 = freeMappedRegs [16, 17, fReg 16, fReg 17]
argRegs 3 = freeMappedRegs [16, 17, 18, fReg 16, fReg 17, fReg 18]
argRegs 4 = freeMappedRegs [16, 17, 18, 19, fReg 16, fReg 17, fReg 18, fReg 19]
argRegs 5 = freeMappedRegs [16, 17, 18, 19, 20, fReg 16, fReg 17, fReg 18, fReg 19, fReg 20]
argRegs 6 = freeMappedRegs [16, 17, 18, 19, 20, 21, fReg 16, fReg 17, fReg 18, fReg 19, fReg 20, fReg 21]
+argRegs _ = panic "MachRegs.argRegs(alpha): don't know about >6 arguments!"
#endif {- alpha_TARGET_ARCH -}
+
#if sparc_TARGET_ARCH
-argRegs 1 = freeMappedRegs (map oReg [0])
-argRegs 2 = freeMappedRegs (map oReg [0,1])
-argRegs 3 = freeMappedRegs (map oReg [0,1,2])
-argRegs 4 = freeMappedRegs (map oReg [0,1,2,3])
-argRegs 5 = freeMappedRegs (map oReg [0,1,2,3,4])
-argRegs 6 = freeMappedRegs (map oReg [0,1,2,3,4,5])
+argRegs 0 = []
+argRegs 1 = map (RealReg . oReg) [0]
+argRegs 2 = map (RealReg . oReg) [0,1]
+argRegs 3 = map (RealReg . oReg) [0,1,2]
+argRegs 4 = map (RealReg . oReg) [0,1,2,3]
+argRegs 5 = map (RealReg . oReg) [0,1,2,3,4]
+argRegs 6 = map (RealReg . oReg) [0,1,2,3,4,5]
+argRegs _ = panic "MachRegs.argRegs(sparc): don't know about >6 arguments!"
#endif {- sparc_TARGET_ARCH -}
-argRegs _ = panic "MachRegs.argRegs: don't know about >6 arguments!"
-#endif {- i386_TARGET_ARCH -}
-#endif
-------------------------------
-
-#if 0
+-- all of the arg regs ??
#if alpha_TARGET_ARCH
allArgRegs :: [(Reg, Reg)]
-
allArgRegs = [(realReg i, realReg (fReg i)) | i <- [16..21]]
#endif {- alpha_TARGET_ARCH -}
#if sparc_TARGET_ARCH
allArgRegs :: [Reg]
-
-allArgRegs = map realReg [oReg i | i <- [0..5]]
+allArgRegs = map RealReg [oReg i | i <- [0..5]]
#endif {- sparc_TARGET_ARCH -}
+
+#if i386_TARGET_ARCH
+allArgRegs :: [Reg]
+allArgRegs = panic "MachRegs.allArgRegs(x86): should not be used!"
#endif
\end{code}
\begin{code}
-freeReg :: FAST_INT -> FAST_BOOL
+freeReg :: Int -> FastBool
#if alpha_TARGET_ARCH
-freeReg ILIT(26) = _FALSE_ -- return address (ra)
-freeReg ILIT(28) = _FALSE_ -- reserved for the assembler (at)
-freeReg ILIT(29) = _FALSE_ -- global pointer (gp)
-freeReg ILIT(30) = _FALSE_ -- stack pointer (sp)
-freeReg ILIT(31) = _FALSE_ -- always zero (zeroh)
-freeReg ILIT(63) = _FALSE_ -- always zero (f31)
+freeReg 26 = fastBool False -- return address (ra)
+freeReg 28 = fastBool False -- reserved for the assembler (at)
+freeReg 29 = fastBool False -- global pointer (gp)
+freeReg 30 = fastBool False -- stack pointer (sp)
+freeReg 31 = fastBool False -- always zero (zeroh)
+freeReg 63 = fastBool False -- always zero (f31)
#endif
#if i386_TARGET_ARCH
-freeReg ILIT(esp) = _FALSE_ -- %esp is the C stack pointer
+freeReg esp = fastBool False -- %esp is the C stack pointer
#endif
#if sparc_TARGET_ARCH
-freeReg ILIT(g0) = _FALSE_ -- %g0 is always 0.
-freeReg ILIT(g5) = _FALSE_ -- %g5 is reserved (ABI).
-freeReg ILIT(g6) = _FALSE_ -- %g6 is reserved (ABI).
-freeReg ILIT(g7) = _FALSE_ -- %g7 is reserved (ABI).
-freeReg ILIT(i6) = _FALSE_ -- %i6 is our frame pointer.
-freeReg ILIT(o6) = _FALSE_ -- %o6 is our stack pointer.
+freeReg g0 = fastBool False -- %g0 is always 0.
+freeReg g5 = fastBool False -- %g5 is reserved (ABI).
+freeReg g6 = fastBool False -- %g6 is reserved (ABI).
+freeReg g7 = fastBool False -- %g7 is reserved (ABI).
+freeReg i6 = fastBool False -- %i6 is our frame pointer.
+freeReg o6 = fastBool False -- %o6 is our stack pointer.
+freeReg f0 = fastBool False -- %f0/%f1 are the C fp return registers.
+freeReg f1 = fastBool False
#endif
#ifdef REG_Base
-freeReg ILIT(REG_Base) = _FALSE_
+freeReg REG_Base = fastBool False
#endif
#ifdef REG_R1
-freeReg ILIT(REG_R1) = _FALSE_
+freeReg REG_R1 = fastBool False
#endif
#ifdef REG_R2
-freeReg ILIT(REG_R2) = _FALSE_
+freeReg REG_R2 = fastBool False
#endif
#ifdef REG_R3
-freeReg ILIT(REG_R3) = _FALSE_
+freeReg REG_R3 = fastBool False
#endif
#ifdef REG_R4
-freeReg ILIT(REG_R4) = _FALSE_
+freeReg REG_R4 = fastBool False
#endif
#ifdef REG_R5
-freeReg ILIT(REG_R5) = _FALSE_
+freeReg REG_R5 = fastBool False
#endif
#ifdef REG_R6
-freeReg ILIT(REG_R6) = _FALSE_
+freeReg REG_R6 = fastBool False
#endif
#ifdef REG_R7
-freeReg ILIT(REG_R7) = _FALSE_
+freeReg REG_R7 = fastBool False
#endif
#ifdef REG_R8
-freeReg ILIT(REG_R8) = _FALSE_
+freeReg REG_R8 = fastBool False
#endif
#ifdef REG_F1
-freeReg ILIT(REG_F1) = _FALSE_
+freeReg REG_F1 = fastBool False
#endif
#ifdef REG_F2
-freeReg ILIT(REG_F2) = _FALSE_
+freeReg REG_F2 = fastBool False
#endif
#ifdef REG_F3
-freeReg ILIT(REG_F3) = _FALSE_
+freeReg REG_F3 = fastBool False
#endif
#ifdef REG_F4
-freeReg ILIT(REG_F4) = _FALSE_
+freeReg REG_F4 = fastBool False
#endif
#ifdef REG_D1
-freeReg ILIT(REG_D1) = _FALSE_
+freeReg REG_D1 = fastBool False
#endif
#ifdef REG_D2
-freeReg ILIT(REG_D2) = _FALSE_
+freeReg REG_D2 = fastBool False
#endif
#ifdef REG_Sp
-freeReg ILIT(REG_Sp) = _FALSE_
+freeReg REG_Sp = fastBool False
#endif
#ifdef REG_Su
-freeReg ILIT(REG_Su) = _FALSE_
+freeReg REG_Su = fastBool False
#endif
#ifdef REG_SpLim
-freeReg ILIT(REG_SpLim) = _FALSE_
+freeReg REG_SpLim = fastBool False
#endif
#ifdef REG_Hp
-freeReg ILIT(REG_Hp) = _FALSE_
+freeReg REG_Hp = fastBool False
#endif
#ifdef REG_HpLim
-freeReg ILIT(REG_HpLim) = _FALSE_
-#endif
-freeReg n
- -- we hang onto two double regs for dedicated
- -- use; this is not necessary on Alphas and
- -- may not be on other non-SPARCs.
-#ifdef REG_D1
- | n _EQ_ (ILIT(REG_D1) _ADD_ ILIT(1)) = _FALSE_
-#endif
-#ifdef REG_D2
- | n _EQ_ (ILIT(REG_D2) _ADD_ ILIT(1)) = _FALSE_
+freeReg REG_HpLim = fastBool False
#endif
- | otherwise = _TRUE_
+freeReg n = fastBool True
\end{code}