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module GHC.Cmm.CallConv (
ParamLocation(..),
assignArgumentsPos,
assignStack,
realArgRegsCover,
tupleRegsCover
) where
import GHC.Prelude
import Data.List (nub)
import GHC.Cmm.Expr
import GHC.Runtime.Heap.Layout
import GHC.Cmm (Convention(..))
import GHC.Cmm.Ppr () -- For Outputable instances
import GHC.Platform
import GHC.Platform.Profile
import GHC.Utils.Outputable
import GHC.Utils.Panic
-- Calculate the 'GlobalReg' or stack locations for function call
-- parameters as used by the Cmm calling convention.
data ParamLocation
= RegisterParam GlobalReg
| StackParam ByteOff
instance Outputable ParamLocation where
ppr (RegisterParam g) = ppr g
ppr (StackParam p) = ppr p
-- |
-- Given a list of arguments, and a function that tells their types,
-- return a list showing where each argument is passed
--
assignArgumentsPos :: Profile
-> ByteOff -- stack offset to start with
-> Convention
-> (a -> CmmType) -- how to get a type from an arg
-> [a] -- args
-> (
ByteOff -- bytes of stack args
, [(a, ParamLocation)] -- args and locations
)
assignArgumentsPos profile off conv arg_ty reps = (stk_off, assignments)
where
platform = profilePlatform profile
regs = case (reps, conv) of
(_, NativeNodeCall) -> getRegsWithNode platform
(_, NativeDirectCall) -> getRegsWithoutNode platform
([_], NativeReturn) -> allRegs platform
(_, NativeReturn) -> getRegsWithNode platform
-- GC calling convention *must* put values in registers
(_, GC) -> allRegs platform
(_, Slow) -> nodeOnly
-- The calling conventions first assign arguments to registers,
-- then switch to the stack when we first run out of registers
-- (even if there are still available registers for args of a
-- different type). When returning an unboxed tuple, we also
-- separate the stack arguments by pointerhood.
(reg_assts, stk_args) = assign_regs [] reps regs
(stk_off, stk_assts) = assignStack platform off arg_ty stk_args
assignments = reg_assts ++ stk_assts
assign_regs assts [] _ = (assts, [])
assign_regs assts (r:rs) regs | isVecType ty = vec
| isFloatType ty = float
| otherwise = int
where vec = case (w, regs) of
(W128, (vs, fs, ds, ls, s:ss))
| passVectorInReg W128 profile -> k (RegisterParam (XmmReg s), (vs, fs, ds, ls, ss))
(W256, (vs, fs, ds, ls, s:ss))
| passVectorInReg W256 profile -> k (RegisterParam (YmmReg s), (vs, fs, ds, ls, ss))
(W512, (vs, fs, ds, ls, s:ss))
| passVectorInReg W512 profile -> k (RegisterParam (ZmmReg s), (vs, fs, ds, ls, ss))
_ -> (assts, (r:rs))
float = case (w, regs) of
(W32, (vs, fs, ds, ls, s:ss))
| passFloatInXmm -> k (RegisterParam (FloatReg s), (vs, fs, ds, ls, ss))
(W32, (vs, f:fs, ds, ls, ss))
| not passFloatInXmm -> k (RegisterParam f, (vs, fs, ds, ls, ss))
(W64, (vs, fs, ds, ls, s:ss))
| passFloatInXmm -> k (RegisterParam (DoubleReg s), (vs, fs, ds, ls, ss))
(W64, (vs, fs, d:ds, ls, ss))
| not passFloatInXmm -> k (RegisterParam d, (vs, fs, ds, ls, ss))
_ -> (assts, (r:rs))
int = case (w, regs) of
(W128, _) -> panic "W128 unsupported register type"
(_, (v:vs, fs, ds, ls, ss)) | widthInBits w <= widthInBits (wordWidth platform)
-> k (RegisterParam (v gcp), (vs, fs, ds, ls, ss))
(_, (vs, fs, ds, l:ls, ss)) | widthInBits w > widthInBits (wordWidth platform)
-> k (RegisterParam l, (vs, fs, ds, ls, ss))
_ -> (assts, (r:rs))
k (asst, regs') = assign_regs ((r, asst) : assts) rs regs'
ty = arg_ty r
w = typeWidth ty
!gcp | isGcPtrType ty = VGcPtr
| otherwise = VNonGcPtr
passFloatInXmm = passFloatArgsInXmm platform
passFloatArgsInXmm :: Platform -> Bool
passFloatArgsInXmm platform = case platformArch platform of
ArchX86_64 -> True
ArchX86 -> False
_ -> False
-- We used to spill vector registers to the stack since the LLVM backend didn't
-- support vector registers in its calling convention. However, this has now
-- been fixed. This function remains only as a convenient way to re-enable
-- spilling when debugging code generation.
passVectorInReg :: Width -> Profile -> Bool
passVectorInReg _ _ = True
assignStack :: Platform -> ByteOff -> (a -> CmmType) -> [a]
-> (
ByteOff -- bytes of stack args
, [(a, ParamLocation)] -- args and locations
)
assignStack platform offset arg_ty args = assign_stk offset [] (reverse args)
where
assign_stk offset assts [] = (offset, assts)
assign_stk offset assts (r:rs)
= assign_stk off' ((r, StackParam off') : assts) rs
where w = typeWidth (arg_ty r)
off' = offset + size
-- Stack arguments always take a whole number of words, we never
-- pack them unlike constructor fields.
size = roundUpToWords platform (widthInBytes w)
-----------------------------------------------------------------------------
-- Local information about the registers available
type AvailRegs = ( [VGcPtr -> GlobalReg] -- available vanilla regs.
, [GlobalReg] -- floats
, [GlobalReg] -- doubles
, [GlobalReg] -- longs (int64 and word64)
, [Int] -- XMM (floats and doubles)
)
-- Vanilla registers can contain pointers, Ints, Chars.
-- Floats and doubles have separate register supplies.
--
-- We take these register supplies from the *real* registers, i.e. those
-- that are guaranteed to map to machine registers.
getRegsWithoutNode, getRegsWithNode :: Platform -> AvailRegs
getRegsWithoutNode platform =
( filter (\r -> r VGcPtr /= node) (realVanillaRegs platform)
, realFloatRegs platform
, realDoubleRegs platform
, realLongRegs platform
, realXmmRegNos platform)
-- getRegsWithNode uses R1/node even if it isn't a register
getRegsWithNode platform =
( if null (realVanillaRegs platform)
then [VanillaReg 1]
else realVanillaRegs platform
, realFloatRegs platform
, realDoubleRegs platform
, realLongRegs platform
, realXmmRegNos platform)
allFloatRegs, allDoubleRegs, allLongRegs :: Platform -> [GlobalReg]
allVanillaRegs :: Platform -> [VGcPtr -> GlobalReg]
allXmmRegs :: Platform -> [Int]
allVanillaRegs platform = map VanillaReg $ regList (pc_MAX_Vanilla_REG (platformConstants platform))
allFloatRegs platform = map FloatReg $ regList (pc_MAX_Float_REG (platformConstants platform))
allDoubleRegs platform = map DoubleReg $ regList (pc_MAX_Double_REG (platformConstants platform))
allLongRegs platform = map LongReg $ regList (pc_MAX_Long_REG (platformConstants platform))
allXmmRegs platform = regList (pc_MAX_XMM_REG (platformConstants platform))
realFloatRegs, realDoubleRegs, realLongRegs :: Platform -> [GlobalReg]
realVanillaRegs :: Platform -> [VGcPtr -> GlobalReg]
realVanillaRegs platform = map VanillaReg $ regList (pc_MAX_Real_Vanilla_REG (platformConstants platform))
realFloatRegs platform = map FloatReg $ regList (pc_MAX_Real_Float_REG (platformConstants platform))
realDoubleRegs platform = map DoubleReg $ regList (pc_MAX_Real_Double_REG (platformConstants platform))
realLongRegs platform = map LongReg $ regList (pc_MAX_Real_Long_REG (platformConstants platform))
realXmmRegNos :: Platform -> [Int]
realXmmRegNos platform
| isSse2Enabled platform = regList (pc_MAX_Real_XMM_REG (platformConstants platform))
| otherwise = []
regList :: Int -> [Int]
regList n = [1 .. n]
allRegs :: Platform -> AvailRegs
allRegs platform = ( allVanillaRegs platform
, allFloatRegs platform
, allDoubleRegs platform
, allLongRegs platform
, allXmmRegs platform
)
nodeOnly :: AvailRegs
nodeOnly = ([VanillaReg 1], [], [], [], [])
-- This returns the set of global registers that *cover* the machine registers
-- used for argument passing. On platforms where registers can overlap---right
-- now just x86-64, where Float and Double registers overlap---passing this set
-- of registers is guaranteed to preserve the contents of all live registers. We
-- only use this functionality in hand-written C-- code in the RTS.
realArgRegsCover :: Platform -> [GlobalReg]
realArgRegsCover platform
| passFloatArgsInXmm platform
= map ($ VGcPtr) (realVanillaRegs platform) ++
realLongRegs platform ++
realDoubleRegs platform -- we only need to save the low Double part of XMM registers.
-- Moreover, the NCG can't load/store full XMM
-- registers for now...
| otherwise
= map ($ VGcPtr) (realVanillaRegs platform) ++
realFloatRegs platform ++
realDoubleRegs platform ++
realLongRegs platform
-- we don't save XMM registers if they are not used for parameter passing
-- Like realArgRegsCover but always includes the node. This covers the real
-- and virtual registers used for unboxed tuples.
--
-- Note: if anything changes in how registers for unboxed tuples overlap,
-- make sure to also update GHC.StgToByteCode.layoutTuple.
tupleRegsCover :: Platform -> [GlobalReg]
tupleRegsCover platform =
nub (VanillaReg 1 VGcPtr : realArgRegsCover platform)
|
