{-# LANGUAGE GADTs, TypeFamilies, FlexibleContexts, FlexibleInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

----------------------------------------------------------------------------
--
-- Pretty-printing of Cmm as (a superset of) C--
--
-- (c) The University of Glasgow 2004-2006
--
-----------------------------------------------------------------------------
--
-- This is where we walk over CmmNode emitting an external representation,
-- suitable for parsing, in a syntax strongly reminiscent of C--. This
-- is the "External Core" for the Cmm layer.
--
-- As such, this should be a well-defined syntax: we want it to look nice.
-- Thus, we try wherever possible to use syntax defined in [1],
-- "The C-- Reference Manual", http://www.cminusminus.org/. We differ
-- slightly, in some cases. For one, we use I8 .. I64 for types, rather
-- than C--'s bits8 .. bits64.
--
-- We try to ensure that all information available in the abstract
-- syntax is reproduced, or reproducible, in the concrete syntax.
-- Data that is not in printed out can be reconstructed according to
-- conventions used in the pretty printer. There are at least two such
-- cases:
--      1) if a value has wordRep type, the type is not appended in the
--      output.
--      2) MachOps that operate over wordRep type are printed in a
--      C-style, rather than as their internal MachRep name.
--
-- These conventions produce much more readable Cmm output.
--
-- A useful example pass over Cmm is in nativeGen/MachCodeGen.hs

module PprCmm
  ( module PprCmmDecl
  , module PprCmmExpr
  )
where

import BlockId ()
import CLabel
import Cmm
import CmmUtils
import FastString
import Outputable
import PprCmmDecl
import PprCmmExpr
import Util

import BasicTypes
import Compiler.Hoopl
import Data.List
import Prelude hiding (succ)

-------------------------------------------------
-- Outputable instances

instance Outputable CmmStackInfo where
    ppr = pprStackInfo

instance Outputable CmmTopInfo where
    ppr = pprTopInfo


instance Outputable (CmmNode e x) where
    ppr = pprNode

instance Outputable Convention where
    ppr = pprConvention

instance Outputable ForeignConvention where
    ppr = pprForeignConvention

instance Outputable ForeignTarget where
    ppr = pprForeignTarget

instance Outputable CmmReturnInfo where
    ppr = pprReturnInfo

instance Outputable (Block CmmNode C C) where
    ppr = pprBlock
instance Outputable (Block CmmNode C O) where
    ppr = pprBlock
instance Outputable (Block CmmNode O C) where
    ppr = pprBlock
instance Outputable (Block CmmNode O O) where
    ppr = pprBlock

instance Outputable (Graph CmmNode e x) where
    ppr = pprGraph

instance Outputable CmmGraph where
    ppr = pprCmmGraph

----------------------------------------------------------
-- Outputting types Cmm contains

pprStackInfo :: CmmStackInfo -> SDoc
pprStackInfo (StackInfo {arg_space=arg_space, updfr_space=updfr_space}) =
  ptext (sLit "arg_space: ") <> ppr arg_space <+>
  ptext (sLit "updfr_space: ") <> ppr updfr_space

pprTopInfo :: CmmTopInfo -> SDoc
pprTopInfo (TopInfo {info_tbls=info_tbl, stack_info=stack_info}) =
  vcat [ptext (sLit "info_tbl: ") <> ppr info_tbl,
        ptext (sLit "stack_info: ") <> ppr stack_info]

----------------------------------------------------------
-- Outputting blocks and graphs

pprBlock :: IndexedCO x SDoc SDoc ~ SDoc
         => Block CmmNode e x -> IndexedCO e SDoc SDoc
pprBlock block
    = foldBlockNodesB3 ( ($$) . ppr
                       , ($$) . (nest 4) . ppr
                       , ($$) . (nest 4) . ppr
                       )
                       block
                       empty

pprGraph :: Graph CmmNode e x -> SDoc
pprGraph GNil = empty
pprGraph (GUnit block) = ppr block
pprGraph (GMany entry body exit)
   = text "{"
  $$ nest 2 (pprMaybeO entry $$ (vcat $ map ppr $ bodyToBlockList body) $$ pprMaybeO exit)
  $$ text "}"
  where pprMaybeO :: Outputable (Block CmmNode e x)
                  => MaybeO ex (Block CmmNode e x) -> SDoc
        pprMaybeO NothingO = empty
        pprMaybeO (JustO block) = ppr block

pprCmmGraph :: CmmGraph -> SDoc
pprCmmGraph g
   = text "{" <> text "offset"
  $$ nest 2 (vcat $ map ppr blocks)
  $$ text "}"
  where blocks = postorderDfs g

---------------------------------------------
-- Outputting CmmNode and types which it contains

pprConvention :: Convention -> SDoc
pprConvention (NativeNodeCall   {}) = text "<native-node-call-convention>"
pprConvention (NativeDirectCall {}) = text "<native-direct-call-convention>"
pprConvention (NativeReturn {})     = text "<native-ret-convention>"
pprConvention  Slow                 = text "<slow-convention>"
pprConvention  GC                   = text "<gc-convention>"

pprForeignConvention :: ForeignConvention -> SDoc
pprForeignConvention (ForeignConvention c args res ret) =
          doubleQuotes (ppr c) <+> text "arg hints: " <+> ppr args <+> text " result hints: " <+> ppr res <+> ppr ret

pprReturnInfo :: CmmReturnInfo -> SDoc
pprReturnInfo CmmMayReturn = empty
pprReturnInfo CmmNeverReturns = ptext (sLit "never returns")

pprForeignTarget :: ForeignTarget -> SDoc
pprForeignTarget (ForeignTarget fn c) = ppr c <+> ppr_target fn
  where
        ppr_target :: CmmExpr -> SDoc
        ppr_target t@(CmmLit _) = ppr t
        ppr_target fn'          = parens (ppr fn')

pprForeignTarget (PrimTarget op)
 -- HACK: We're just using a ForeignLabel to get this printed, the label
 --       might not really be foreign.
 = ppr
               (CmmLabel (mkForeignLabel
                         (mkFastString (show op))
                         Nothing ForeignLabelInThisPackage IsFunction))

pprNode :: CmmNode e x -> SDoc
pprNode node = pp_node <+> pp_debug
  where
    pp_node :: SDoc
    pp_node = case node of
      -- label:
      CmmEntry id -> ppr id <> colon

      -- // text
      CmmComment s -> text "//" <+> ftext s

      -- reg = expr;
      CmmAssign reg expr -> ppr reg <+> equals <+> ppr expr <> semi

      -- rep[lv] = expr;
      CmmStore lv expr -> rep <> brackets(ppr lv) <+> equals <+> ppr expr <> semi
          where
            rep = sdocWithDynFlags $ \dflags ->
                  ppr ( cmmExprType dflags expr )

      -- call "ccall" foo(x, y)[r1, r2];
      -- ToDo ppr volatile
      CmmUnsafeForeignCall target results args ->
          hsep [ ppUnless (null results) $
                    parens (commafy $ map ppr results) <+> equals,
                 ptext $ sLit "call",
                 ppr target <> parens (commafy $ map ppr args) <> semi]

      -- goto label;
      CmmBranch ident -> ptext (sLit "goto") <+> ppr ident <> semi

      -- if (expr) goto t; else goto f;
      CmmCondBranch expr t f ->
          hsep [ ptext (sLit "if")
               , parens(ppr expr)
               , ptext (sLit "goto")
               , ppr t <> semi
               , ptext (sLit "else goto")
               , ppr f <> semi
               ]

      CmmSwitch expr maybe_ids ->
          hang (hcat [ ptext (sLit "switch [0 .. ")
                     , int (length maybe_ids - 1)
                     , ptext (sLit "] ")
                     , if isTrivialCmmExpr expr
                       then ppr expr
                       else parens (ppr expr)
                     , ptext (sLit " {")
                     ])
             4 (vcat ( map caseify pairs )) $$ rbrace
          where pairs = groupBy snds (zip [0 .. ] maybe_ids )
                snds a b = (snd a) == (snd b)
                caseify ixs@((_,Nothing):_) = ptext (sLit "/* impossible: ")
                                              <> hcat (intersperse comma (map (int.fst) ixs)) <> ptext (sLit " */")
                caseify as = let (is,ids) = unzip as
                             in hsep [ ptext (sLit "case")
                                     , hcat (punctuate comma (map int is))
                                     , ptext (sLit ": goto")
                                     , ppr (head [ id | Just id <- ids]) <> semi ]

      CmmCall tgt k regs out res updfr_off ->
          hcat [ ptext (sLit "call"), space
               , pprFun tgt, parens (interpp'SP regs), space
               , returns <+>
                 ptext (sLit "args: ") <> ppr out <> comma <+>
                 ptext (sLit "res: ") <> ppr res <> comma <+>
                 ptext (sLit "upd: ") <> ppr updfr_off
               , semi ]
          where pprFun f@(CmmLit _) = ppr f
                pprFun f = parens (ppr f)

                returns
                  | Just r <- k = ptext (sLit "returns to") <+> ppr r <> comma
                  | otherwise   = empty

      CmmForeignCall {tgt=t, res=rs, args=as, succ=s, ret_args=a, ret_off=u, intrbl=i} ->
          hcat $ if i then [ptext (sLit "interruptible"), space] else [] ++
               [ ptext (sLit "foreign call"), space
               , ppr t, ptext (sLit "(...)"), space
               , ptext (sLit "returns to") <+> ppr s
                    <+> ptext (sLit "args:") <+> parens (ppr as)
                    <+> ptext (sLit "ress:") <+> parens (ppr rs)
               , ptext (sLit "ret_args:") <+> ppr a
               , ptext (sLit "ret_off:") <+> ppr u
               , semi ]

    pp_debug :: SDoc
    pp_debug =
      if not debugIsOn then empty
      else case node of
             CmmEntry {}             -> empty -- Looks terrible with text "  // CmmEntry"
             CmmComment {}           -> empty -- Looks also terrible with text "  // CmmComment"
             CmmAssign {}            -> text "  // CmmAssign"
             CmmStore {}             -> text "  // CmmStore"
             CmmUnsafeForeignCall {} -> text "  // CmmUnsafeForeignCall"
             CmmBranch {}            -> text "  // CmmBranch"
             CmmCondBranch {}        -> text "  // CmmCondBranch"
             CmmSwitch {}            -> text "  // CmmSwitch"
             CmmCall {}              -> text "  // CmmCall"
             CmmForeignCall {}       -> text "  // CmmForeignCall"

    commafy :: [SDoc] -> SDoc
    commafy xs = hsep $ punctuate comma xs
