ghci/ByteCodeInstr.hs

    {-# LANGUAGE CPP, MagicHash #-}
    {-# OPTIONS_GHC -funbox-strict-fields #-}
    --
    --  (c) The University of Glasgow 2002-2006
    --

    -- | ByteCodeInstrs: Bytecode instruction definitions
    module ByteCodeInstr (
            BCInstr(..), ProtoBCO(..), bciStackUse,
      ) where

    #include "HsVersions.h"
    #include "../includes/MachDeps.h"

    import ByteCodeTypes
    import GHCi.RemoteTypes
    import GHCi.FFI (C_ffi_cif)
    import StgCmmLayout     ( ArgRep(..) )
    import PprCore
    import Outputable
    import FastString
    import Name
    import Unique
    import Id
    import CoreSyn
    import Literal
    import DataCon
    import VarSet
    import PrimOp
    import SMRep

    import Data.Word
    #if MIN_VERSION_base(4,9,0)
    import GHC.Stack.CCS (CostCentre)
    #else
    import GHC.Stack (CostCentre)
    #endif

    -- ----------------------------------------------------------------------------
    -- Bytecode instructions

    data ProtoBCO a
       = ProtoBCO {
            protoBCOName       :: a,          -- name, in some sense
            protoBCOInstrs     :: [BCInstr],  -- instrs
            -- arity and GC info
            protoBCOBitmap     :: [StgWord],
            protoBCOBitmapSize :: Word16,
            protoBCOArity      :: Int,
            -- what the BCO came from
            protoBCOExpr       :: Either  [AnnAlt Id DVarSet] (AnnExpr Id DVarSet),
            -- malloc'd pointers
            protoBCOFFIs       :: [FFIInfo]
       }

    type LocalLabel = Word16

    data BCInstr
       -- Messing with the stack
       = STKCHECK  Word

       -- Push locals (existing bits of the stack)
       | PUSH_L    !Word16{-offset-}
       | PUSH_LL   !Word16 !Word16{-2 offsets-}
       | PUSH_LLL  !Word16 !Word16 !Word16{-3 offsets-}

       -- Push a ptr  (these all map to PUSH_G really)
       | PUSH_G       Name
       | PUSH_PRIMOP  PrimOp
       | PUSH_BCO     (ProtoBCO Name)

       -- Push an alt continuation
       | PUSH_ALTS          (ProtoBCO Name)
       | PUSH_ALTS_UNLIFTED (ProtoBCO Name) ArgRep

       -- Pushing literals
       | PUSH_UBX  Literal Word16
            -- push this int/float/double/addr, on the stack. Word16
            -- is # of words to copy from literal pool.  Eitherness reflects
            -- the difficulty of dealing with MachAddr here, mostly due to
            -- the excessive (and unnecessary) restrictions imposed by the
            -- designers of the new Foreign library.  In particular it is
            -- quite impossible to convert an Addr to any other integral
            -- type, and it appears impossible to get hold of the bits of
            -- an addr, even though we need to assemble BCOs.

       -- various kinds of application
       | PUSH_APPLY_N
       | PUSH_APPLY_V
       | PUSH_APPLY_F
       | PUSH_APPLY_D
       | PUSH_APPLY_L
       | PUSH_APPLY_P
       | PUSH_APPLY_PP
       | PUSH_APPLY_PPP
       | PUSH_APPLY_PPPP
       | PUSH_APPLY_PPPPP
       | PUSH_APPLY_PPPPPP

       | SLIDE     Word16{-this many-} Word16{-down by this much-}

       -- To do with the heap
       | ALLOC_AP  !Word16 -- make an AP with this many payload words
       | ALLOC_AP_NOUPD !Word16 -- make an AP_NOUPD with this many payload words
       | ALLOC_PAP !Word16 !Word16 -- make a PAP with this arity / payload words
       | MKAP      !Word16{-ptr to AP is this far down stack-} !Word16{-number of words-}
       | MKPAP     !Word16{-ptr to PAP is this far down stack-} !Word16{-number of words-}
       | UNPACK    !Word16 -- unpack N words from t.o.s Constr
       | PACK      DataCon !Word16
                            -- after assembly, the DataCon is an index into the
                            -- itbl array
       -- For doing case trees
       | LABEL     LocalLabel
       | TESTLT_I  Int    LocalLabel
       | TESTEQ_I  Int    LocalLabel
       | TESTLT_W  Word   LocalLabel
       | TESTEQ_W  Word   LocalLabel
       | TESTLT_F  Float  LocalLabel
       | TESTEQ_F  Float  LocalLabel
       | TESTLT_D  Double LocalLabel
       | TESTEQ_D  Double LocalLabel

       -- The Word16 value is a constructor number and therefore
       -- stored in the insn stream rather than as an offset into
       -- the literal pool.
       | TESTLT_P  Word16 LocalLabel
       | TESTEQ_P  Word16 LocalLabel

       | CASEFAIL
       | JMP              LocalLabel

       -- For doing calls to C (via glue code generated by libffi)
       | CCALL            Word16    -- stack frame size
                          (RemotePtr C_ffi_cif) -- addr of the glue code
                          Word16    -- whether or not the call is interruptible
                                    -- (XXX: inefficient, but I don't know
                                    -- what the alignment constraints are.)

       -- For doing magic ByteArray passing to foreign calls
       | SWIZZLE          Word16 -- to the ptr N words down the stack,
                          Word16 -- add M (interpreted as a signed 16-bit entity)

       -- To Infinity And Beyond
       | ENTER
       | RETURN             -- return a lifted value
       | RETURN_UBX ArgRep -- return an unlifted value, here's its rep

       -- Breakpoints
       | BRK_FUN          Word16 Unique (RemotePtr CostCentre)

    -- -----------------------------------------------------------------------------
    -- Printing bytecode instructions

    instance Outputable a => Outputable (ProtoBCO a) where
       ppr (ProtoBCO name instrs bitmap bsize arity origin ffis)
          = (text "ProtoBCO" <+> ppr name <> char '#' <> int arity
                    <+> text (show ffis) <> colon)
            $$ nest 3 (case origin of
                          Left alts -> vcat (zipWith (<+>) (char '{' : repeat (char ';'))
                                                           (map (pprCoreAltShort.deAnnAlt) alts)) <+> char '}'
                          Right rhs -> pprCoreExprShort (deAnnotate rhs))
            $$ nest 3 (text "bitmap: " <+> text (show bsize) <+> ppr bitmap)
            $$ nest 3 (vcat (map ppr instrs))

    -- Print enough of the Core expression to enable the reader to find
    -- the expression in the -ddump-prep output.  That is, we need to
    -- include at least a binder.

    pprCoreExprShort :: CoreExpr -> SDoc
    pprCoreExprShort expr@(Lam _ _)
      = let
            (bndrs, _) = collectBinders expr
        in
        char '\\' <+> sep (map (pprBndr LambdaBind) bndrs) <+> arrow <+> text "..."

    pprCoreExprShort (Case _expr var _ty _alts)
     = text "case of" <+> ppr var

    pprCoreExprShort (Let (NonRec x _) _) = text "let" <+> ppr x <+> ptext (sLit ("= ... in ..."))
    pprCoreExprShort (Let (Rec bs) _) = text "let {" <+> ppr (fst (head bs)) <+> ptext (sLit ("= ...; ... } in ..."))

    pprCoreExprShort (Tick t e) = ppr t <+> pprCoreExprShort e
    pprCoreExprShort (Cast e _) = pprCoreExprShort e <+> text "`cast` T"

    pprCoreExprShort e = pprCoreExpr e

    pprCoreAltShort :: CoreAlt -> SDoc
    pprCoreAltShort (con, args, expr) = ppr con <+> sep (map ppr args) <+> text "->" <+> pprCoreExprShort expr

    instance Outputable BCInstr where
       ppr (STKCHECK n)          = text "STKCHECK" <+> ppr n
       ppr (PUSH_L offset)       = text "PUSH_L  " <+> ppr offset
       ppr (PUSH_LL o1 o2)       = text "PUSH_LL " <+> ppr o1 <+> ppr o2
       ppr (PUSH_LLL o1 o2 o3)   = text "PUSH_LLL" <+> ppr o1 <+> ppr o2 <+> ppr o3
       ppr (PUSH_G nm)           = text "PUSH_G  " <+> ppr nm
       ppr (PUSH_PRIMOP op)      = text "PUSH_G  " <+> text "GHC.PrimopWrappers."
                                                   <> ppr op
       ppr (PUSH_BCO bco)        = hang (text "PUSH_BCO") 2 (ppr bco)
       ppr (PUSH_ALTS bco)       = hang (text "PUSH_ALTS") 2 (ppr bco)
       ppr (PUSH_ALTS_UNLIFTED bco pk) = hang (text "PUSH_ALTS_UNLIFTED" <+> ppr pk) 2 (ppr bco)

       ppr (PUSH_UBX lit nw)     = text "PUSH_UBX" <+> parens (ppr nw) <+> ppr lit
       ppr PUSH_APPLY_N          = text "PUSH_APPLY_N"
       ppr PUSH_APPLY_V          = text "PUSH_APPLY_V"
       ppr PUSH_APPLY_F          = text "PUSH_APPLY_F"
       ppr PUSH_APPLY_D          = text "PUSH_APPLY_D"
       ppr PUSH_APPLY_L          = text "PUSH_APPLY_L"
       ppr PUSH_APPLY_P          = text "PUSH_APPLY_P"
       ppr PUSH_APPLY_PP         = text "PUSH_APPLY_PP"
       ppr PUSH_APPLY_PPP        = text "PUSH_APPLY_PPP"
       ppr PUSH_APPLY_PPPP       = text "PUSH_APPLY_PPPP"
       ppr PUSH_APPLY_PPPPP      = text "PUSH_APPLY_PPPPP"
       ppr PUSH_APPLY_PPPPPP     = text "PUSH_APPLY_PPPPPP"

       ppr (SLIDE n d)           = text "SLIDE   " <+> ppr n <+> ppr d
       ppr (ALLOC_AP sz)         = text "ALLOC_AP   " <+> ppr sz
       ppr (ALLOC_AP_NOUPD sz)   = text "ALLOC_AP_NOUPD   " <+> ppr sz
       ppr (ALLOC_PAP arity sz)  = text "ALLOC_PAP   " <+> ppr arity <+> ppr sz
       ppr (MKAP offset sz)      = text "MKAP    " <+> ppr sz <+> text "words,"
                                                   <+> ppr offset <+> text "stkoff"
       ppr (MKPAP offset sz)     = text "MKPAP   " <+> ppr sz <+> text "words,"
                                                   <+> ppr offset <+> text "stkoff"
       ppr (UNPACK sz)           = text "UNPACK  " <+> ppr sz
       ppr (PACK dcon sz)        = text "PACK    " <+> ppr dcon <+> ppr sz
       ppr (LABEL     lab)       = text "__"       <> ppr lab <> colon
       ppr (TESTLT_I  i lab)     = text "TESTLT_I" <+> int i <+> text "__" <> ppr lab
       ppr (TESTEQ_I  i lab)     = text "TESTEQ_I" <+> int i <+> text "__" <> ppr lab
       ppr (TESTLT_W  i lab)     = text "TESTLT_W" <+> int (fromIntegral i) <+> text "__" <> ppr lab
       ppr (TESTEQ_W  i lab)     = text "TESTEQ_W" <+> int (fromIntegral i) <+> text "__" <> ppr lab
       ppr (TESTLT_F  f lab)     = text "TESTLT_F" <+> float f <+> text "__" <> ppr lab
       ppr (TESTEQ_F  f lab)     = text "TESTEQ_F" <+> float f <+> text "__" <> ppr lab
       ppr (TESTLT_D  d lab)     = text "TESTLT_D" <+> double d <+> text "__" <> ppr lab
       ppr (TESTEQ_D  d lab)     = text "TESTEQ_D" <+> double d <+> text "__" <> ppr lab
       ppr (TESTLT_P  i lab)     = text "TESTLT_P" <+> ppr i <+> text "__" <> ppr lab
       ppr (TESTEQ_P  i lab)     = text "TESTEQ_P" <+> ppr i <+> text "__" <> ppr lab
       ppr CASEFAIL              = text "CASEFAIL"
       ppr (JMP lab)             = text "JMP"      <+> ppr lab
       ppr (CCALL off marshall_addr int) = text "CCALL   " <+> ppr off
                                                    <+> text "marshall code at"
                                                   <+> text (show marshall_addr)
                                                   <+> (if int == 1
                                                        then text "(interruptible)"
                                                        else empty)
       ppr (SWIZZLE stkoff n)    = text "SWIZZLE " <+> text "stkoff" <+> ppr stkoff
                                                   <+> text "by" <+> ppr n
       ppr ENTER                 = text "ENTER"
       ppr RETURN                = text "RETURN"
       ppr (RETURN_UBX pk)       = text "RETURN_UBX  " <+> ppr pk
       ppr (BRK_FUN index uniq _cc) = text "BRK_FUN" <+> ppr index <+> ppr uniq <+> text "<cc>"

    -- -----------------------------------------------------------------------------
    -- The stack use, in words, of each bytecode insn.  These _must_ be
    -- correct, or overestimates of reality, to be safe.

    -- NOTE: we aggregate the stack use from case alternatives too, so that
    -- we can do a single stack check at the beginning of a function only.

    -- This could all be made more accurate by keeping track of a proper
    -- stack high water mark, but it doesn't seem worth the hassle.

    protoBCOStackUse :: ProtoBCO a -> Word
    protoBCOStackUse bco = sum (map bciStackUse (protoBCOInstrs bco))

    bciStackUse :: BCInstr -> Word
    bciStackUse STKCHECK{}            = 0
    bciStackUse PUSH_L{}              = 1
    bciStackUse PUSH_LL{}             = 2
    bciStackUse PUSH_LLL{}            = 3
    bciStackUse PUSH_G{}              = 1
    bciStackUse PUSH_PRIMOP{}         = 1
    bciStackUse PUSH_BCO{}            = 1
    bciStackUse (PUSH_ALTS bco)       = 2 + protoBCOStackUse bco
    bciStackUse (PUSH_ALTS_UNLIFTED bco _) = 2 + protoBCOStackUse bco
    bciStackUse (PUSH_UBX _ nw)       = fromIntegral nw
    bciStackUse PUSH_APPLY_N{}        = 1
    bciStackUse PUSH_APPLY_V{}        = 1
    bciStackUse PUSH_APPLY_F{}        = 1
    bciStackUse PUSH_APPLY_D{}        = 1
    bciStackUse PUSH_APPLY_L{}        = 1
    bciStackUse PUSH_APPLY_P{}        = 1
    bciStackUse PUSH_APPLY_PP{}       = 1
    bciStackUse PUSH_APPLY_PPP{}      = 1
    bciStackUse PUSH_APPLY_PPPP{}     = 1
    bciStackUse PUSH_APPLY_PPPPP{}    = 1
    bciStackUse PUSH_APPLY_PPPPPP{}   = 1
    bciStackUse ALLOC_AP{}            = 1
    bciStackUse ALLOC_AP_NOUPD{}      = 1
    bciStackUse ALLOC_PAP{}           = 1
    bciStackUse (UNPACK sz)           = fromIntegral sz
    bciStackUse LABEL{}               = 0
    bciStackUse TESTLT_I{}            = 0
    bciStackUse TESTEQ_I{}            = 0
    bciStackUse TESTLT_W{}            = 0
    bciStackUse TESTEQ_W{}            = 0
    bciStackUse TESTLT_F{}            = 0
    bciStackUse TESTEQ_F{}            = 0
    bciStackUse TESTLT_D{}            = 0
    bciStackUse TESTEQ_D{}            = 0
    bciStackUse TESTLT_P{}            = 0
    bciStackUse TESTEQ_P{}            = 0
    bciStackUse CASEFAIL{}            = 0
    bciStackUse JMP{}                 = 0
    bciStackUse ENTER{}               = 0
    bciStackUse RETURN{}              = 0
    bciStackUse RETURN_UBX{}          = 1
    bciStackUse CCALL{}               = 0
    bciStackUse SWIZZLE{}             = 0
    bciStackUse BRK_FUN{}             = 0

    -- These insns actually reduce stack use, but we need the high-tide level,
    -- so can't use this info.  Not that it matters much.
    bciStackUse SLIDE{}               = 0
    bciStackUse MKAP{}                = 0
    bciStackUse MKPAP{}               = 0
    bciStackUse PACK{}                = 1 -- worst case is PACK 0 words