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|
-- | Formats on this architecture
-- A Format is a combination of width and class
--
-- TODO: Signed vs unsigned?
--
-- TODO: This module is currenly shared by all architectures because
-- NCGMonad need to know about it to make a VReg. It would be better
-- to have architecture specific formats, and do the overloading
-- properly. eg SPARC doesn't care about FF80.
--
module Format (
Format(..),
ScalarFormat(..),
intFormat,
floatFormat,
isFloatFormat,
isVecFormat,
cmmTypeFormat,
formatToWidth,
formatInBytes
)
where
import GhcPrelude
import Cmm
import Outputable
-- Note [GHC's data format representations]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- GHC has severals types that represent various aspects of data format.
-- These include:
--
-- * 'CmmType.CmmType': The data classification used throughout the C--
-- pipeline. This is a pair of a CmmCat and a Width.
--
-- * 'CmmType.CmmCat': What the bits in a C-- value mean (e.g. a pointer, integer, or floating-point value)
--
-- * 'CmmType.Width': The width of a C-- value.
--
-- * 'CmmType.Length': The width (measured in number of scalars) of a vector value.
--
-- * 'Format.Format': The data format representation used by much of the backend.
--
-- * 'Format.ScalarFormat': The format of a 'Format.VecFormat'\'s scalar.
--
-- * 'RegClass.RegClass': Whether a register is an integer, float-point, or vector register
--
-- It looks very like the old MachRep, but it's now of purely local
-- significance, here in the native code generator. You can change it
-- without global consequences.
--
-- A major use is as an opcode qualifier; thus the opcode
-- mov.l a b
-- might be encoded
-- MOV II32 a b
-- where the Format field encodes the ".l" part.
-- ToDo: it's not clear to me that we need separate signed-vs-unsigned formats
-- here. I've removed them from the x86 version, we'll see what happens --SDM
-- ToDo: quite a few occurrences of Format could usefully be replaced by Width
data Format
= II8
| II16
| II32
| II64
| FF32
| FF64
| VecFormat !Length !ScalarFormat !Width
deriving (Show, Eq)
data ScalarFormat = FmtInt8
| FmtInt16
| FmtInt32
| FmtInt64
| FmtFloat
| FmtDouble
deriving (Show, Eq)
-- | Get the integer format of this width.
intFormat :: Width -> Format
intFormat width
= case width of
W8 -> II8
W16 -> II16
W32 -> II32
W64 -> II64
other -> sorry $ "The native code generator cannot " ++
"produce code for Format.intFormat " ++ show other
++ "\n\tConsider using the llvm backend with -fllvm"
-- | Get the float format of this width.
floatFormat :: Width -> Format
floatFormat width
= case width of
W32 -> FF32
W64 -> FF64
other -> pprPanic "Format.floatFormat" (ppr other)
-- | Check if a format represents a floating point value.
isFloatFormat :: Format -> Bool
isFloatFormat format
= case format of
FF32 -> True
FF64 -> True
_ -> False
-- | Check if a format represents a vector
isVecFormat :: Format -> Bool
isVecFormat (VecFormat {}) = True
isVecFormat _ = False
-- | Convert a Cmm type to a Format.
cmmTypeFormat :: CmmType -> Format
cmmTypeFormat ty
| isFloatType ty = floatFormat (typeWidth ty)
| isVecType ty = vecFormat ty
| otherwise = intFormat (typeWidth ty)
vecFormat :: CmmType -> Format
vecFormat ty =
let l = vecLength ty
elemTy = vecElemType ty
in if isFloatType elemTy
then case typeWidth elemTy of
W32 -> VecFormat l FmtFloat W32
W64 -> VecFormat l FmtDouble W64
_ -> pprPanic "Incorrect vector element width" (ppr elemTy)
else case typeWidth elemTy of
W8 -> VecFormat l FmtInt8 W8
W16 -> VecFormat l FmtInt16 W16
W32 -> VecFormat l FmtInt32 W32
W64 -> VecFormat l FmtInt64 W64
_ -> pprPanic "Incorrect vector element width" (ppr elemTy)
-- | Get the Width of a Format.
formatToWidth :: Format -> Width
formatToWidth format
= case format of
II8 -> W8
II16 -> W16
II32 -> W32
II64 -> W64
FF32 -> W32
FF64 -> W64
VecFormat l _ w -> widthFromBytes (l*widthInBytes w)
formatInBytes :: Format -> Int
formatInBytes = widthInBytes . formatToWidth
|
