llvmGen/LlvmCodeGen/Data.hs

    {-# LANGUAGE CPP #-}
    -- ----------------------------------------------------------------------------
    -- | Handle conversion of CmmData to LLVM code.
    --

    module LlvmCodeGen.Data (
            genLlvmData, genData
        ) where

    #include "HsVersions.h"

    import Llvm
    import LlvmCodeGen.Base

    import BlockId
    import CLabel
    import Cmm
    import DynFlags

    import FastString
    import Outputable

    -- ----------------------------------------------------------------------------
    -- * Constants
    --

    -- | The string appended to a variable name to create its structure type alias
    structStr :: LMString
    structStr = fsLit "_struct"

    -- ----------------------------------------------------------------------------
    -- * Top level
    --

    -- | Pass a CmmStatic section to an equivalent Llvm code.
    genLlvmData :: (Section, CmmStatics) -> LlvmM LlvmData
    genLlvmData (sec, Statics lbl xs) = do
        label <- strCLabel_llvm lbl
        static <- mapM genData xs
        lmsec <- llvmSection sec
        let types   = map getStatType static

            strucTy = LMStruct types
            tyAlias = LMAlias ((label `appendFS` structStr), strucTy)

            struct         = Just $ LMStaticStruc static tyAlias
            link           = if (externallyVisibleCLabel lbl)
                                then ExternallyVisible else Internal
            const          = if isSecConstant sec then Constant else Global
            varDef         = LMGlobalVar label tyAlias link lmsec Nothing const
            globDef        = LMGlobal varDef struct

        return ([globDef], [tyAlias])

    -- | Should a data in this section be considered constant
    isSecConstant :: Section -> Bool
    isSecConstant (Section t _) = case t of
        Text                    -> True
        ReadOnlyData            -> True
        RelocatableReadOnlyData -> True
        ReadOnlyData16          -> True
        Data                    -> False
        UninitialisedData       -> False
        (OtherSection _)        -> False

    -- | Format the section type part of a Cmm Section
    llvmSectionType :: SectionType -> FastString
    llvmSectionType t = case t of
        Text                    -> fsLit ".text"
        ReadOnlyData            -> fsLit ".rodata"
        RelocatableReadOnlyData -> fsLit ".data.rel.ro"
        ReadOnlyData16          -> fsLit ".rodata.cst16"
        Data                    -> fsLit ".data"
        UninitialisedData       -> fsLit ".bss"
        (OtherSection _)        -> panic "llvmSectionType: unknown section type"

    -- | Format a Cmm Section into a LLVM section name
    llvmSection :: Section -> LlvmM LMSection
    llvmSection (Section t suffix) = do
      dflags <- getDynFlags
      let splitSect = gopt Opt_SplitSections dflags
      if not splitSect
      then return Nothing
      else do
        lmsuffix <- strCLabel_llvm suffix
        return (Just (concatFS [llvmSectionType t, fsLit ".", lmsuffix]))

    -- ----------------------------------------------------------------------------
    -- * Generate static data
    --

    -- | Handle static data
    genData :: CmmStatic -> LlvmM LlvmStatic

    genData (CmmString str) = do
        let v  = map (\x -> LMStaticLit $ LMIntLit (fromIntegral x) i8) str
            ve = v ++ [LMStaticLit $ LMIntLit 0 i8]
        return $ LMStaticArray ve (LMArray (length ve) i8)

    genData (CmmUninitialised bytes)
        = return $ LMUninitType (LMArray bytes i8)

    genData (CmmStaticLit lit)
        = genStaticLit lit

    -- | Generate Llvm code for a static literal.
    --
    -- Will either generate the code or leave it unresolved if it is a 'CLabel'
    -- which isn't yet known.
    genStaticLit :: CmmLit -> LlvmM LlvmStatic
    genStaticLit (CmmInt i w)
        = return $ LMStaticLit (LMIntLit i (LMInt $ widthInBits w))

    genStaticLit (CmmFloat r w)
        = return $ LMStaticLit (LMFloatLit (fromRational r) (widthToLlvmFloat w))

    genStaticLit (CmmVec ls)
        = do sls <- mapM toLlvmLit ls
             return $ LMStaticLit (LMVectorLit sls)
      where
        toLlvmLit :: CmmLit -> LlvmM LlvmLit
        toLlvmLit lit = do
          slit <- genStaticLit lit
          case slit of
            LMStaticLit llvmLit -> return llvmLit
            _ -> panic "genStaticLit"

    -- Leave unresolved, will fix later
    genStaticLit cmm@(CmmLabel l) = do
        var <- getGlobalPtr =<< strCLabel_llvm l
        dflags <- getDynFlags
        let ptr = LMStaticPointer var
            lmty = cmmToLlvmType $ cmmLitType dflags cmm
        return $ LMPtoI ptr lmty

    genStaticLit (CmmLabelOff label off) = do
        dflags <- getDynFlags
        var <- genStaticLit (CmmLabel label)
        let offset = LMStaticLit $ LMIntLit (toInteger off) (llvmWord dflags)
        return $ LMAdd var offset

    genStaticLit (CmmLabelDiffOff l1 l2 off) = do
        dflags <- getDynFlags
        var1 <- genStaticLit (CmmLabel l1)
        var2 <- genStaticLit (CmmLabel l2)
        let var = LMSub var1 var2
            offset = LMStaticLit $ LMIntLit (toInteger off) (llvmWord dflags)
        return $ LMAdd var offset

    genStaticLit (CmmBlock b) = genStaticLit $ CmmLabel $ infoTblLbl b

    genStaticLit (CmmHighStackMark)
        = panic "genStaticLit: CmmHighStackMark unsupported!"