nativeGen/SPARC/CodeGen.hs

    {-# LANGUAGE CPP #-}

    -----------------------------------------------------------------------------
    --
    -- Generating machine code (instruction selection)
    --
    -- (c) The University of Glasgow 1996-2013
    --
    -----------------------------------------------------------------------------

    {-# LANGUAGE GADTs #-}
    module SPARC.CodeGen (
            cmmTopCodeGen,
            generateJumpTableForInstr,
            InstrBlock
    )

    where

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

    -- NCG stuff:
    import GhcPrelude

    import SPARC.Base
    import SPARC.CodeGen.Sanity
    import SPARC.CodeGen.Amode
    import SPARC.CodeGen.CondCode
    import SPARC.CodeGen.Gen64
    import SPARC.CodeGen.Gen32
    import SPARC.CodeGen.Base
    import SPARC.Ppr        ()
    import SPARC.Instr
    import SPARC.Imm
    import SPARC.AddrMode
    import SPARC.Regs
    import SPARC.Stack
    import Instruction
    import Format
    import NCGMonad

    -- Our intermediate code:
    import BlockId
    import Cmm
    import CmmUtils
    import CmmSwitch
    import Hoopl.Block
    import Hoopl.Graph
    import PIC
    import Reg
    import CLabel
    import CPrim

    -- The rest:
    import BasicTypes
    import DynFlags
    import FastString
    import OrdList
    import Outputable
    import Platform

    import Control.Monad    ( mapAndUnzipM )

    -- | Top level code generation
    cmmTopCodeGen :: RawCmmDecl
                  -> NatM [NatCmmDecl CmmStatics Instr]

    cmmTopCodeGen (CmmProc info lab live graph)
     = do let blocks = toBlockListEntryFirst graph
          (nat_blocks,statics) <- mapAndUnzipM basicBlockCodeGen blocks

          let proc = CmmProc info lab live (ListGraph $ concat nat_blocks)
          let tops = proc : concat statics

          return tops

    cmmTopCodeGen (CmmData sec dat) = do
      return [CmmData sec dat]  -- no translation, we just use CmmStatic

    -- | Do code generation on a single block of CMM code.
    --      code generation may introduce new basic block boundaries, which
    --      are indicated by the NEWBLOCK instruction.  We must split up the
    --      instruction stream into basic blocks again.  Also, we extract
    --      LDATAs here too.
    basicBlockCodeGen :: CmmBlock
                      -> NatM ( [NatBasicBlock Instr]
                              , [NatCmmDecl CmmStatics Instr])

    basicBlockCodeGen block = do
      let (_, nodes, tail)  = blockSplit block
          id = entryLabel block
          stmts = blockToList nodes
      mid_instrs <- stmtsToInstrs stmts
      tail_instrs <- stmtToInstrs tail
      let instrs = mid_instrs `appOL` tail_instrs
      let
            (top,other_blocks,statics)
                    = foldrOL mkBlocks ([],[],[]) instrs

            mkBlocks (NEWBLOCK id) (instrs,blocks,statics)
              = ([], BasicBlock id instrs : blocks, statics)

            mkBlocks (LDATA sec dat) (instrs,blocks,statics)
              = (instrs, blocks, CmmData sec dat:statics)

            mkBlocks instr (instrs,blocks,statics)
              = (instr:instrs, blocks, statics)

            -- do intra-block sanity checking
            blocksChecked
                    = map (checkBlock block)
                    $ BasicBlock id top : other_blocks

      return (blocksChecked, statics)

    -- | Convert some Cmm statements to SPARC instructions.
    stmtsToInstrs :: [CmmNode e x] -> NatM InstrBlock
    stmtsToInstrs stmts
       = do instrss <- mapM stmtToInstrs stmts
            return (concatOL instrss)

    stmtToInstrs :: CmmNode e x -> NatM InstrBlock
    stmtToInstrs stmt = do
      dflags <- getDynFlags
      case stmt of
        CmmComment s   -> return (unitOL (COMMENT s))
        CmmTick {}     -> return nilOL
        CmmUnwind {}   -> return nilOL

        CmmAssign reg src
          | isFloatType ty  -> assignReg_FltCode format reg src
          | isWord64 ty     -> assignReg_I64Code        reg src
          | otherwise       -> assignReg_IntCode format reg src
            where ty = cmmRegType dflags reg
                  format = cmmTypeFormat ty

        CmmStore addr src
          | isFloatType ty  -> assignMem_FltCode format addr src
          | isWord64 ty     -> assignMem_I64Code      addr src
          | otherwise       -> assignMem_IntCode format addr src
            where ty = cmmExprType dflags src
                  format = cmmTypeFormat ty

        CmmUnsafeForeignCall target result_regs args
           -> genCCall target result_regs args

        CmmBranch   id              -> genBranch id
        CmmCondBranch arg true false _ -> do
          b1 <- genCondJump true arg
          b2 <- genBranch false
          return (b1 `appOL` b2)
        CmmSwitch arg ids   -> do dflags <- getDynFlags
                                  genSwitch dflags arg ids
        CmmCall { cml_target = arg } -> genJump arg

        _
         -> panic "stmtToInstrs: statement should have been cps'd away"

    {-
    Now, given a tree (the argument to a CmmLoad) that references memory,
    produce a suitable addressing mode.

    A Rule of the Game (tm) for Amodes: use of the addr bit must
    immediately follow use of the code part, since the code part puts
    values in registers which the addr then refers to.  So you can't put
    anything in between, lest it overwrite some of those registers.  If
    you need to do some other computation between the code part and use of
    the addr bit, first store the effective address from the amode in a
    temporary, then do the other computation, and then use the temporary:

        code
        LEA amode, tmp
        ... other computation ...
        ... (tmp) ...
    -}

    -- | Convert a BlockId to some CmmStatic data
    jumpTableEntry :: DynFlags -> Maybe BlockId -> CmmStatic
    jumpTableEntry dflags Nothing = CmmStaticLit (CmmInt 0 (wordWidth dflags))
    jumpTableEntry _ (Just blockid) = CmmStaticLit (CmmLabel blockLabel)
        where blockLabel = blockLbl blockid

    -- -----------------------------------------------------------------------------
    -- Generating assignments

    -- Assignments are really at the heart of the whole code generation
    -- business.  Almost all top-level nodes of any real importance are
    -- assignments, which correspond to loads, stores, or register
    -- transfers.  If we're really lucky, some of the register transfers
    -- will go away, because we can use the destination register to
    -- complete the code generation for the right hand side.  This only
    -- fails when the right hand side is forced into a fixed register
    -- (e.g. the result of a call).

    assignMem_IntCode :: Format -> CmmExpr -> CmmExpr -> NatM InstrBlock
    assignMem_IntCode pk addr src = do
        (srcReg, code) <- getSomeReg src
        Amode dstAddr addr_code <- getAmode addr
        return $ code `appOL` addr_code `snocOL` ST pk srcReg dstAddr

    assignReg_IntCode :: Format -> CmmReg  -> CmmExpr -> NatM InstrBlock
    assignReg_IntCode _ reg src = do
        dflags <- getDynFlags
        r <- getRegister src
        let dst = getRegisterReg (targetPlatform dflags) reg
        return $ case r of
            Any _ code         -> code dst
            Fixed _ freg fcode -> fcode `snocOL` OR False g0 (RIReg freg) dst

    -- Floating point assignment to memory
    assignMem_FltCode :: Format -> CmmExpr -> CmmExpr -> NatM InstrBlock
    assignMem_FltCode pk addr src = do
        dflags <- getDynFlags
        Amode dst__2 code1 <- getAmode addr
        (src__2, code2) <- getSomeReg src
        tmp1 <- getNewRegNat pk
        let
            pk__2   = cmmExprType dflags src
            code__2 = code1 `appOL` code2 `appOL`
                if   formatToWidth pk == typeWidth pk__2
                then unitOL (ST pk src__2 dst__2)
                else toOL   [ FxTOy (cmmTypeFormat pk__2) pk src__2 tmp1
                            , ST    pk tmp1 dst__2]
        return code__2

    -- Floating point assignment to a register/temporary
    assignReg_FltCode :: Format -> CmmReg  -> CmmExpr -> NatM InstrBlock
    assignReg_FltCode pk dstCmmReg srcCmmExpr = do
        dflags <- getDynFlags
        let platform = targetPlatform dflags
        srcRegister <- getRegister srcCmmExpr
        let dstReg  = getRegisterReg platform dstCmmReg

        return $ case srcRegister of
            Any _ code                  -> code dstReg
            Fixed _ srcFixedReg srcCode -> srcCode `snocOL` FMOV pk srcFixedReg dstReg

    genJump :: CmmExpr{-the branch target-} -> NatM InstrBlock

    genJump (CmmLit (CmmLabel lbl))
      = return (toOL [CALL (Left target) 0 True, NOP])
      where
        target = ImmCLbl lbl

    genJump tree
      = do
            (target, code) <- getSomeReg tree
            return (code `snocOL` JMP (AddrRegReg target g0)  `snocOL` NOP)

    -- -----------------------------------------------------------------------------
    --  Unconditional branches

    genBranch :: BlockId -> NatM InstrBlock
    genBranch = return . toOL . mkJumpInstr

    -- -----------------------------------------------------------------------------
    --  Conditional jumps

    {-
    Conditional jumps are always to local labels, so we can use branch
    instructions.  We peek at the arguments to decide what kind of
    comparison to do.

    SPARC: First, we have to ensure that the condition codes are set
    according to the supplied comparison operation.  We generate slightly
    different code for floating point comparisons, because a floating
    point operation cannot directly precede a @BF@.  We assume the worst
    and fill that slot with a @NOP@.

    SPARC: Do not fill the delay slots here; you will confuse the register
    allocator.
    -}

    genCondJump
        :: BlockId      -- the branch target
        -> CmmExpr      -- the condition on which to branch
        -> NatM InstrBlock

    genCondJump bid bool = do
      CondCode is_float cond code <- getCondCode bool
      return (
           code `appOL`
           toOL (
             if   is_float
             then [NOP, BF cond False bid, NOP]
             else [BI cond False bid, NOP]
           )
        )

    -- -----------------------------------------------------------------------------
    -- Generating a table-branch

    genSwitch :: DynFlags -> CmmExpr -> SwitchTargets -> NatM InstrBlock
    genSwitch dflags expr targets
            | positionIndependent dflags
            = error "MachCodeGen: sparc genSwitch PIC not finished\n"

            | otherwise
            = do    (e_reg, e_code) <- getSomeReg (cmmOffset dflags expr offset)

                    base_reg        <- getNewRegNat II32
                    offset_reg      <- getNewRegNat II32
                    dst             <- getNewRegNat II32

                    label           <- getNewLabelNat

                    return $ e_code `appOL`
                     toOL
                            [ -- load base of jump table
                              SETHI (HI (ImmCLbl label)) base_reg
                            , OR    False base_reg (RIImm $ LO $ ImmCLbl label) base_reg

                            -- the addrs in the table are 32 bits wide..
                            , SLL   e_reg (RIImm $ ImmInt 2) offset_reg

                            -- load and jump to the destination
                            , LD      II32 (AddrRegReg base_reg offset_reg) dst
                            , JMP_TBL (AddrRegImm dst (ImmInt 0)) ids label
                            , NOP ]
      where (offset, ids) = switchTargetsToTable targets

    generateJumpTableForInstr :: DynFlags -> Instr
                              -> Maybe (NatCmmDecl CmmStatics Instr)
    generateJumpTableForInstr dflags (JMP_TBL _ ids label) =
      let jumpTable = map (jumpTableEntry dflags) ids
      in Just (CmmData (Section ReadOnlyData label) (Statics label jumpTable))
    generateJumpTableForInstr _ _ = Nothing

    -- -----------------------------------------------------------------------------
    -- Generating C calls

    {-
       Now the biggest nightmare---calls.  Most of the nastiness is buried in
       @get_arg@, which moves the arguments to the correct registers/stack
       locations.  Apart from that, the code is easy.

       The SPARC calling convention is an absolute
       nightmare.  The first 6x32 bits of arguments are mapped into
       %o0 through %o5, and the remaining arguments are dumped to the
       stack, beginning at [%sp+92].  (Note that %o6 == %sp.)

       If we have to put args on the stack, move %o6==%sp down by
       the number of words to go on the stack, to ensure there's enough space.

       According to Fraser and Hanson's lcc book, page 478, fig 17.2,
       16 words above the stack pointer is a word for the address of
       a structure return value.  I use this as a temporary location
       for moving values from float to int regs.  Certainly it isn't
       safe to put anything in the 16 words starting at %sp, since
       this area can get trashed at any time due to window overflows
       caused by signal handlers.

       A final complication (if the above isn't enough) is that
       we can't blithely calculate the arguments one by one into
       %o0 .. %o5.  Consider the following nested calls:

           fff a (fff b c)

       Naive code moves a into %o0, and (fff b c) into %o1.  Unfortunately
       the inner call will itself use %o0, which trashes the value put there
       in preparation for the outer call.  Upshot: we need to calculate the
       args into temporary regs, and move those to arg regs or onto the
       stack only immediately prior to the call proper.  Sigh.
    -}

    genCCall
        :: ForeignTarget            -- function to call
        -> [CmmFormal]        -- where to put the result
        -> [CmmActual]        -- arguments (of mixed type)
        -> NatM InstrBlock

    -- On SPARC under TSO (Total Store Ordering), writes earlier in the instruction stream
    -- are guaranteed to take place before writes afterwards (unlike on PowerPC).
    -- Ref: Section 8.4 of the SPARC V9 Architecture manual.
    --
    -- In the SPARC case we don't need a barrier.
    --
    genCCall (PrimTarget MO_WriteBarrier) _ _
     = return $ nilOL

    genCCall (PrimTarget (MO_Prefetch_Data _)) _ _
     = return $ nilOL

    genCCall target dest_regs args
     = do   -- work out the arguments, and assign them to integer regs
            argcode_and_vregs       <- mapM arg_to_int_vregs args
            let (argcodes, vregss)  = unzip argcode_and_vregs
            let vregs               = concat vregss

            let n_argRegs           = length allArgRegs
            let n_argRegs_used      = min (length vregs) n_argRegs

            -- deal with static vs dynamic call targets
            callinsns <- case target of
                    ForeignTarget (CmmLit (CmmLabel lbl)) _ ->
                            return (unitOL (CALL (Left (litToImm (CmmLabel lbl))) n_argRegs_used False))

                    ForeignTarget expr _
                     -> do  (dyn_c, [dyn_r]) <- arg_to_int_vregs expr
                            return (dyn_c `snocOL` CALL (Right dyn_r) n_argRegs_used False)

                    PrimTarget mop
                     -> do  res     <- outOfLineMachOp mop
                            lblOrMopExpr <- case res of
                                    Left lbl -> do
                                            return (unitOL (CALL (Left (litToImm (CmmLabel lbl))) n_argRegs_used False))

                                    Right mopExpr -> do
                                            (dyn_c, [dyn_r]) <- arg_to_int_vregs mopExpr
                                            return (dyn_c `snocOL` CALL (Right dyn_r) n_argRegs_used False)

                            return lblOrMopExpr

            let argcode = concatOL argcodes

            let (move_sp_down, move_sp_up)
                       = let diff = length vregs - n_argRegs
                             nn   = if odd diff then diff + 1 else diff -- keep 8-byte alignment
                         in  if   nn <= 0
                             then (nilOL, nilOL)
                             else (unitOL (moveSp (-1*nn)), unitOL (moveSp (1*nn)))

            let transfer_code
                    = toOL (move_final vregs allArgRegs extraStackArgsHere)

            dflags <- getDynFlags
            return
             $      argcode                 `appOL`
                    move_sp_down            `appOL`
                    transfer_code           `appOL`
                    callinsns               `appOL`
                    unitOL NOP              `appOL`
                    move_sp_up              `appOL`
                    assign_code (targetPlatform dflags) dest_regs

    -- | Generate code to calculate an argument, and move it into one
    --      or two integer vregs.
    arg_to_int_vregs :: CmmExpr -> NatM (OrdList Instr, [Reg])
    arg_to_int_vregs arg = do dflags <- getDynFlags
                              arg_to_int_vregs' dflags arg

    arg_to_int_vregs' :: DynFlags -> CmmExpr -> NatM (OrdList Instr, [Reg])
    arg_to_int_vregs' dflags arg

            -- If the expr produces a 64 bit int, then we can just use iselExpr64
            | isWord64 (cmmExprType dflags arg)
            = do    (ChildCode64 code r_lo) <- iselExpr64 arg
                    let r_hi                = getHiVRegFromLo r_lo
                    return (code, [r_hi, r_lo])

            | otherwise
            = do    (src, code)     <- getSomeReg arg
                    let pk          = cmmExprType dflags arg

                    case cmmTypeFormat pk of

                     -- Load a 64 bit float return value into two integer regs.
                     FF64 -> do
                            v1 <- getNewRegNat II32
                            v2 <- getNewRegNat II32

                            let code2 =
                                    code                            `snocOL`
                                    FMOV FF64 src f0                `snocOL`
                                    ST   FF32  f0 (spRel 16)        `snocOL`
                                    LD   II32  (spRel 16) v1        `snocOL`
                                    ST   FF32  f1 (spRel 16)        `snocOL`
                                    LD   II32  (spRel 16) v2

                            return  (code2, [v1,v2])

                     -- Load a 32 bit float return value into an integer reg
                     FF32 -> do
                            v1 <- getNewRegNat II32

                            let code2 =
                                    code                            `snocOL`
                                    ST   FF32  src (spRel 16)       `snocOL`
                                    LD   II32  (spRel 16) v1

                            return (code2, [v1])

                     -- Move an integer return value into its destination reg.
                     _ -> do
                            v1 <- getNewRegNat II32

                            let code2 =
                                    code                            `snocOL`
                                    OR False g0 (RIReg src) v1

                            return (code2, [v1])

    -- | Move args from the integer vregs into which they have been
    --      marshalled, into %o0 .. %o5, and the rest onto the stack.
    --
    move_final :: [Reg] -> [Reg] -> Int -> [Instr]

    -- all args done
    move_final [] _ _
            = []

    -- out of aregs; move to stack
    move_final (v:vs) [] offset
            = ST II32 v (spRel offset)
            : move_final vs [] (offset+1)

    -- move into an arg (%o[0..5]) reg
    move_final (v:vs) (a:az) offset
            = OR False g0 (RIReg v) a
            : move_final vs az offset

    -- | Assign results returned from the call into their
    --      destination regs.
    --
    assign_code :: Platform -> [LocalReg] -> OrdList Instr

    assign_code _ [] = nilOL

    assign_code platform [dest]
     = let  rep     = localRegType dest
            width   = typeWidth rep
            r_dest  = getRegisterReg platform (CmmLocal dest)

            result
                    | isFloatType rep
                    , W32   <- width
                    = unitOL $ FMOV FF32 (regSingle $ fReg 0) r_dest

                    | isFloatType rep
                    , W64   <- width
                    = unitOL $ FMOV FF64 (regSingle $ fReg 0) r_dest

                    | not $ isFloatType rep
                    , W32   <- width
                    = unitOL $ mkRegRegMoveInstr platform (regSingle $ oReg 0) r_dest

                    | not $ isFloatType rep
                    , W64           <- width
                    , r_dest_hi     <- getHiVRegFromLo r_dest
                    = toOL  [ mkRegRegMoveInstr platform (regSingle $ oReg 0) r_dest_hi
                            , mkRegRegMoveInstr platform (regSingle $ oReg 1) r_dest]

                    | otherwise
                    = panic "SPARC.CodeGen.GenCCall: no match"

       in   result

    assign_code _ _
            = panic "SPARC.CodeGen.GenCCall: no match"

    -- | Generate a call to implement an out-of-line floating point operation
    outOfLineMachOp
            :: CallishMachOp
            -> NatM (Either CLabel CmmExpr)

    outOfLineMachOp mop
     = do   let functionName
                    = outOfLineMachOp_table mop

            dflags  <- getDynFlags
            mopExpr <- cmmMakeDynamicReference dflags CallReference
                    $  mkForeignLabel functionName Nothing ForeignLabelInExternalPackage IsFunction

            let mopLabelOrExpr
                    = case mopExpr of
                            CmmLit (CmmLabel lbl)   -> Left lbl
                            _                       -> Right mopExpr

            return mopLabelOrExpr

    -- | Decide what C function to use to implement a CallishMachOp
    --
    outOfLineMachOp_table
            :: CallishMachOp
            -> FastString

    outOfLineMachOp_table mop
     = case mop of
            MO_F32_Exp    -> fsLit "expf"
            MO_F32_Log    -> fsLit "logf"
            MO_F32_Sqrt   -> fsLit "sqrtf"
            MO_F32_Fabs   -> unsupported
            MO_F32_Pwr    -> fsLit "powf"

            MO_F32_Sin    -> fsLit "sinf"
            MO_F32_Cos    -> fsLit "cosf"
            MO_F32_Tan    -> fsLit "tanf"

            MO_F32_Asin   -> fsLit "asinf"
            MO_F32_Acos   -> fsLit "acosf"
            MO_F32_Atan   -> fsLit "atanf"

            MO_F32_Sinh   -> fsLit "sinhf"
            MO_F32_Cosh   -> fsLit "coshf"
            MO_F32_Tanh   -> fsLit "tanhf"

            MO_F64_Exp    -> fsLit "exp"
            MO_F64_Log    -> fsLit "log"
            MO_F64_Sqrt   -> fsLit "sqrt"
            MO_F64_Fabs   -> unsupported
            MO_F64_Pwr    -> fsLit "pow"

            MO_F64_Sin    -> fsLit "sin"
            MO_F64_Cos    -> fsLit "cos"
            MO_F64_Tan    -> fsLit "tan"

            MO_F64_Asin   -> fsLit "asin"
            MO_F64_Acos   -> fsLit "acos"
            MO_F64_Atan   -> fsLit "atan"

            MO_F64_Sinh   -> fsLit "sinh"
            MO_F64_Cosh   -> fsLit "cosh"
            MO_F64_Tanh   -> fsLit "tanh"

            MO_UF_Conv w -> fsLit $ word2FloatLabel w

            MO_Memcpy _  -> fsLit "memcpy"
            MO_Memset _  -> fsLit "memset"
            MO_Memmove _ -> fsLit "memmove"
            MO_Memcmp _  -> fsLit "memcmp"

            MO_BSwap w   -> fsLit $ bSwapLabel w
            MO_PopCnt w  -> fsLit $ popCntLabel w
            MO_Clz w     -> fsLit $ clzLabel w
            MO_Ctz w     -> fsLit $ ctzLabel w
            MO_AtomicRMW w amop -> fsLit $ atomicRMWLabel w amop
            MO_Cmpxchg w -> fsLit $ cmpxchgLabel w
            MO_AtomicRead w -> fsLit $ atomicReadLabel w
            MO_AtomicWrite w -> fsLit $ atomicWriteLabel w

            MO_S_QuotRem {}  -> unsupported
            MO_U_QuotRem {}  -> unsupported
            MO_U_QuotRem2 {} -> unsupported
            MO_Add2 {}       -> unsupported
            MO_SubWordC {}   -> unsupported
            MO_AddIntC {}    -> unsupported
            MO_SubIntC {}    -> unsupported
            MO_U_Mul2 {}     -> unsupported
            MO_WriteBarrier  -> unsupported
            MO_Touch         -> unsupported
            (MO_Prefetch_Data _) -> unsupported
        where unsupported = panic ("outOfLineCmmOp: " ++ show mop
                                ++ " not supported here")