path: root/compiler/nativeGen/X86/Ppr.hs

{-# LANGUAGE CPP #-}

-----------------------------------------------------------------------------
--
-- Pretty-printing assembly language
--
-- (c) The University of Glasgow 1993-2005
--
-----------------------------------------------------------------------------

{-# OPTIONS_GHC -fno-warn-orphans #-}
module X86.Ppr (
        pprNatCmmDecl,
        pprData,
        pprInstr,
        pprFormat,
        pprImm,
        pprDataItem,
)

where

#include "HsVersions.h"

import GhcPrelude

import X86.Regs
import X86.Instr
import X86.Cond
import Instruction
import Format
import Reg
import PprBase


import Hoopl.Collections
import Hoopl.Label
import BasicTypes       (Alignment, mkAlignment, alignmentBytes)
import DynFlags
import Cmm              hiding (topInfoTable)
import BlockId
import Module           ( Module )
import CLabel
import Unique           ( pprUniqueAlways )
import GHC.Platform
import FastString
import Outputable

import Data.Word
import Data.Bits

-- -----------------------------------------------------------------------------
-- Printing this stuff out
--
--
-- Note [Subsections Via Symbols]
--
-- If we are using the .subsections_via_symbols directive
-- (available on recent versions of Darwin),
-- we have to make sure that there is some kind of reference
-- from the entry code to a label on the _top_ of of the info table,
-- so that the linker will not think it is unreferenced and dead-strip
-- it. That's why the label is called a DeadStripPreventer (_dsp).
--
-- The LLVM code gen already creates `iTableSuf` symbols, where
-- the X86 would generate the DeadStripPreventer (_dsp) symbol.
-- Therefore all that is left for llvm code gen, is to ensure
-- that all the `iTableSuf` symbols are marked as used.
-- As of this writing the documentation regarding the
-- .subsections_via_symbols and -dead_strip can be found at
-- <https://developer.apple.com/library/mac/documentation/DeveloperTools/Reference/Assembler/040-Assembler_Directives/asm_directives.html#//apple_ref/doc/uid/TP30000823-TPXREF101>

pprProcAlignment :: SDoc
pprProcAlignment = sdocWithDynFlags $ \dflags ->
  (maybe empty (pprAlign . mkAlignment) (cmmProcAlignment dflags))

pprNatCmmDecl :: Module -> NatCmmDecl (Alignment, CmmStatics) Instr -> SDoc
pprNatCmmDecl _this_mod (CmmData section dats) =
  pprSectionAlign section $$ pprDatas dats

pprNatCmmDecl this_mod proc@(CmmProc top_info lbl _ (ListGraph blocks)) =
  pprProcAlignment $$
  case topInfoTable proc of
    Nothing ->
        -- special case for code without info table:
        pprSectionAlign (Section Text lbl) $$
        pprProcAlignment $$
        pprProcLabel this_mod lbl $$
        pprLabel lbl $$ -- blocks guaranteed not null, so label needed
        vcat (map (pprBasicBlock top_info) blocks) $$
        pprBlockEndLabel lbl $$
        pprProcEndLabel lbl $$
        pprSizeDecl lbl

    Just (Statics info_lbl _) ->
      sdocWithPlatform $ \platform ->
      pprSectionAlign (Section Text info_lbl) $$
      pprProcAlignment $$
      pprProcLabel this_mod lbl $$
      (if platformHasSubsectionsViaSymbols platform
          then ppr (mkDeadStripPreventer info_lbl) <> char ':'
          else empty) $$
      vcat (map (pprBasicBlock top_info) blocks) $$
      pprProcEndLabel info_lbl $$
      -- above: Even the first block gets a label, because with branch-chain
      -- elimination, it might be the target of a goto.
      (if platformHasSubsectionsViaSymbols platform
       then -- See Note [Subsections Via Symbols]
                text "\t.long "
            <+> ppr info_lbl
            <+> char '-'
            <+> ppr (mkDeadStripPreventer info_lbl)
       else empty) $$
      pprSizeDecl info_lbl

pprProcLabel :: Module -> CLabel -> SDoc
pprProcLabel this_mod lbl = sdocWithDynFlags $ \dflags ->
    case ppInternalProcLabel dflags this_mod lbl of
      Just lbl' -> lbl' <> char ':'
      Nothing   -> empty

ifDebugLevel :: Int -> SDoc -> SDoc
ifDebugLevel min_lvl doc =
    sdocWithDynFlags $ \dflags ->
        if debugLevel dflags >= min_lvl then doc else empty

pprProcEndLabel :: CLabel -- ^ Procedure name
                -> SDoc
pprProcEndLabel lbl =
    ifDebugLevel 0 $ ppr (mkAsmTempProcEndLabel lbl) <> char ':'

pprBlockEndLabel :: CLabel -- ^ Block name
                 -> SDoc
pprBlockEndLabel lbl =
    ifDebugLevel 0 $ ppr (mkAsmTempEndLabel lbl) <> char ':'

-- | Output the ELF .size directive.
pprSizeDecl :: CLabel -> SDoc
pprSizeDecl lbl
 = sdocWithPlatform $ \platform ->
   if osElfTarget (platformOS platform)
   then text "\t.size" <+> ppr lbl <> ptext (sLit ", .-") <> ppr lbl
   else empty

pprBasicBlock :: LabelMap CmmStatics -> NatBasicBlock Instr -> SDoc
pprBasicBlock info_env (BasicBlock blockid instrs)
  = sdocWithDynFlags $ \dflags ->
    maybe_infotable dflags $
    pprLabel asmLbl $$
    vcat (map pprInstr instrs) $$
    pprBlockEndLabel asmLbl
  where
    asmLbl = blockLbl blockid
    maybe_infotable dflags c = case mapLookup blockid info_env of
       Nothing -> c
       Just (Statics infoLbl info) ->
           pprAlignForSection Text $$
           infoTableLoc $$
           vcat (map pprData info) $$
           pprLabel infoLbl $$
           c $$
           (if debugLevel dflags > 0
            then ppr (mkAsmTempEndLabel infoLbl) <> char ':' else empty)
    -- Make sure the info table has the right .loc for the block
    -- coming right after it. See [Note: Info Offset]
    infoTableLoc = case instrs of
      (l@LOCATION{} : _) -> pprInstr l
      _other             -> empty


pprDatas :: (Alignment, CmmStatics) -> SDoc
-- See note [emit-time elimination of static indirections] in CLabel.
pprDatas (_, Statics alias [CmmStaticLit (CmmLabel lbl), CmmStaticLit ind, _, _])
  | lbl == mkIndStaticInfoLabel
  , let labelInd (CmmLabelOff l _) = Just l
        labelInd (CmmLabel l) = Just l
        labelInd _ = Nothing
  , Just ind' <- labelInd ind
  , alias `mayRedirectTo` ind'
  = pprGloblDecl alias
    $$ text ".equiv" <+> ppr alias <> comma <> ppr (CmmLabel ind')

pprDatas (align, (Statics lbl dats))
 = vcat (pprAlign align : pprLabel lbl : map pprData dats)

pprData :: CmmStatic -> SDoc
pprData (CmmString str) = pprBytes str

pprData (CmmUninitialised bytes)
 = sdocWithPlatform $ \platform ->
   if platformOS platform == OSDarwin then text ".space " <> int bytes
                                      else text ".skip "  <> int bytes

pprData (CmmStaticLit lit) = pprDataItem lit

pprGloblDecl :: CLabel -> SDoc
pprGloblDecl lbl
  | not (externallyVisibleCLabel lbl) = empty
  | otherwise = text ".globl " <> ppr lbl

pprLabelType' :: DynFlags -> CLabel -> SDoc
pprLabelType' dflags lbl =
  if isCFunctionLabel lbl || functionOkInfoTable then
    text "@function"
  else
    text "@object"
  where
    {-
    NOTE: This is a bit hacky.

    With the `tablesNextToCode` info tables look like this:
    ```
      <info table data>
    label_info:
      <info table code>
    ```
    So actually info table label points exactly to the code and we can mark
    the label as @function. (This is required to make perf and potentially other
    tools to work on Haskell binaries).
    This usually works well but it can cause issues with a linker.
    A linker uses different algorithms for the relocation depending on
    the symbol type.For some reason, a linker will generate JUMP_SLOT relocation
    when constructor info table is referenced from a data section.
    This only happens with static constructor call so
    we mark _con_info symbols as `@object` to avoid the issue with relocations.

    @SimonMarlow hack explanation:
    "The reasoning goes like this:

    * The danger when we mark a symbol as `@function` is that the linker will
      redirect it to point to the PLT and use a `JUMP_SLOT` relocation when
      the symbol refers to something outside the current shared object.
      A PLT / JUMP_SLOT reference only works for symbols that we jump to, not
      for symbols representing data,, nor for info table symbol references which
      we expect to point directly to the info table.
    * GHC generates code that might refer to any info table symbol from the text
      segment, but that's OK, because those will be explicit GOT references
      generated by the code generator.
    * When we refer to info tables from the data segment, it's either
      * a FUN_STATIC/THUNK_STATIC local to this module
      * a `con_info` that could be from anywhere

    So, the only info table symbols that we might refer to from the data segment
    of another shared object are `con_info` symbols, so those are the ones we
    need to exclude from getting the @function treatment.
    "

    A good place to check for more
    https://gitlab.haskell.org/ghc/ghc/wikis/commentary/position-independent-code

    Another possible hack is to create an extra local function symbol for
    every code-like thing to give the needed information for to the tools
    but mess up with the relocation. https://phabricator.haskell.org/D4730
    -}
    functionOkInfoTable = tablesNextToCode dflags &&
      isInfoTableLabel lbl && not (isConInfoTableLabel lbl)


pprTypeDecl :: CLabel -> SDoc
pprTypeDecl lbl
    = sdocWithPlatform $ \platform ->
      if osElfTarget (platformOS platform) && externallyVisibleCLabel lbl
      then
        sdocWithDynFlags $ \df ->
          text ".type " <> ppr lbl <> ptext (sLit  ", ") <> pprLabelType' df lbl
      else empty

pprLabel :: CLabel -> SDoc
pprLabel lbl = pprGloblDecl lbl
            $$ pprTypeDecl lbl
            $$ (ppr lbl <> char ':')

pprAlign :: Alignment -> SDoc
pprAlign alignment
        = sdocWithPlatform $ \platform ->
          text ".align " <> int (alignmentOn platform)
  where
        bytes = alignmentBytes alignment
        alignmentOn platform = if platformOS platform == OSDarwin
                               then log2 bytes
                               else      bytes

        log2 :: Int -> Int  -- cache the common ones
        log2 1 = 0
        log2 2 = 1
        log2 4 = 2
        log2 8 = 3
        log2 n = 1 + log2 (n `quot` 2)

-- -----------------------------------------------------------------------------
-- pprInstr: print an 'Instr'

instance Outputable Instr where
    ppr instr = pprInstr instr


pprReg :: Format -> Reg -> SDoc
pprReg f r
  = case r of
      RegReal    (RealRegSingle i) ->
          sdocWithPlatform $ \platform ->
          if target32Bit platform then ppr32_reg_no f i
                                  else ppr64_reg_no f i
      RegReal    (RealRegPair _ _) -> panic "X86.Ppr: no reg pairs on this arch"
      RegVirtual (VirtualRegI  u)  -> text "%vI_"   <> pprUniqueAlways u
      RegVirtual (VirtualRegHi u)  -> text "%vHi_"  <> pprUniqueAlways u
      RegVirtual (VirtualRegF  u)  -> text "%vF_"   <> pprUniqueAlways u
      RegVirtual (VirtualRegD  u)  -> text "%vD_"   <> pprUniqueAlways u

  where
    ppr32_reg_no :: Format -> Int -> SDoc
    ppr32_reg_no II8   = ppr32_reg_byte
    ppr32_reg_no II16  = ppr32_reg_word
    ppr32_reg_no _     = ppr32_reg_long

    ppr32_reg_byte i = ptext
      (case i of {
         0 -> sLit "%al";     1 -> sLit "%bl";
         2 -> sLit "%cl";     3 -> sLit "%dl";
        _  -> sLit $ "very naughty I386 byte register: " ++ show i
      })

    ppr32_reg_word i = ptext
      (case i of {
         0 -> sLit "%ax";     1 -> sLit "%bx";
         2 -> sLit "%cx";     3 -> sLit "%dx";
         4 -> sLit "%si";     5 -> sLit "%di";
         6 -> sLit "%bp";     7 -> sLit "%sp";
        _  -> sLit "very naughty I386 word register"
      })

    ppr32_reg_long i = ptext
      (case i of {
         0 -> sLit "%eax";    1 -> sLit "%ebx";
         2 -> sLit "%ecx";    3 -> sLit "%edx";
         4 -> sLit "%esi";    5 -> sLit "%edi";
         6 -> sLit "%ebp";    7 -> sLit "%esp";
         _  -> ppr_reg_float i
      })

    ppr64_reg_no :: Format -> Int -> SDoc
    ppr64_reg_no II8   = ppr64_reg_byte
    ppr64_reg_no II16  = ppr64_reg_word
    ppr64_reg_no II32  = ppr64_reg_long
    ppr64_reg_no _     = ppr64_reg_quad

    ppr64_reg_byte i = ptext
      (case i of {
         0 -> sLit "%al";     1 -> sLit "%bl";
         2 -> sLit "%cl";     3 -> sLit "%dl";
         4 -> sLit "%sil";    5 -> sLit "%dil"; -- new 8-bit regs!
         6 -> sLit "%bpl";    7 -> sLit "%spl";
         8 -> sLit "%r8b";    9  -> sLit "%r9b";
        10 -> sLit "%r10b";   11 -> sLit "%r11b";
        12 -> sLit "%r12b";   13 -> sLit "%r13b";
        14 -> sLit "%r14b";   15 -> sLit "%r15b";
        _  -> sLit $ "very naughty x86_64 byte register: " ++ show i
      })

    ppr64_reg_word i = ptext
      (case i of {
         0 -> sLit "%ax";     1 -> sLit "%bx";
         2 -> sLit "%cx";     3 -> sLit "%dx";
         4 -> sLit "%si";     5 -> sLit "%di";
         6 -> sLit "%bp";     7 -> sLit "%sp";
         8 -> sLit "%r8w";    9  -> sLit "%r9w";
        10 -> sLit "%r10w";   11 -> sLit "%r11w";
        12 -> sLit "%r12w";   13 -> sLit "%r13w";
        14 -> sLit "%r14w";   15 -> sLit "%r15w";
        _  -> sLit "very naughty x86_64 word register"
      })

    ppr64_reg_long i = ptext
      (case i of {
         0 -> sLit "%eax";    1  -> sLit "%ebx";
         2 -> sLit "%ecx";    3  -> sLit "%edx";
         4 -> sLit "%esi";    5  -> sLit "%edi";
         6 -> sLit "%ebp";    7  -> sLit "%esp";
         8 -> sLit "%r8d";    9  -> sLit "%r9d";
        10 -> sLit "%r10d";   11 -> sLit "%r11d";
        12 -> sLit "%r12d";   13 -> sLit "%r13d";
        14 -> sLit "%r14d";   15 -> sLit "%r15d";
        _  -> sLit "very naughty x86_64 register"
      })

    ppr64_reg_quad i = ptext
      (case i of {
         0 -> sLit "%rax";      1 -> sLit "%rbx";
         2 -> sLit "%rcx";      3 -> sLit "%rdx";
         4 -> sLit "%rsi";      5 -> sLit "%rdi";
         6 -> sLit "%rbp";      7 -> sLit "%rsp";
         8 -> sLit "%r8";       9 -> sLit "%r9";
        10 -> sLit "%r10";    11 -> sLit "%r11";
        12 -> sLit "%r12";    13 -> sLit "%r13";
        14 -> sLit "%r14";    15 -> sLit "%r15";
        _  -> ppr_reg_float i
      })

ppr_reg_float :: Int -> PtrString
ppr_reg_float i = case i of
        16 -> sLit "%xmm0" ;   17 -> sLit "%xmm1"
        18 -> sLit "%xmm2" ;   19 -> sLit "%xmm3"
        20 -> sLit "%xmm4" ;   21 -> sLit "%xmm5"
        22 -> sLit "%xmm6" ;   23 -> sLit "%xmm7"
        24 -> sLit "%xmm8" ;   25 -> sLit "%xmm9"
        26 -> sLit "%xmm10";   27 -> sLit "%xmm11"
        28 -> sLit "%xmm12";   29 -> sLit "%xmm13"
        30 -> sLit "%xmm14";   31 -> sLit "%xmm15"
        _  -> sLit "very naughty x86 register"

pprFormat :: Format -> SDoc
pprFormat x
 = ptext (case x of
                II8   -> sLit "b"
                II16  -> sLit "w"
                II32  -> sLit "l"
                II64  -> sLit "q"
                FF32  -> sLit "ss"      -- "scalar single-precision float" (SSE2)
                FF64  -> sLit "sd"      -- "scalar double-precision float" (SSE2)
                )

pprFormat_x87 :: Format -> SDoc
pprFormat_x87 x
  = ptext $ case x of
                FF32  -> sLit "s"
                FF64  -> sLit "l"
                _     -> panic "X86.Ppr.pprFormat_x87"


pprCond :: Cond -> SDoc
pprCond c
 = ptext (case c of {
                GEU     -> sLit "ae";   LU    -> sLit "b";
                EQQ     -> sLit "e";    GTT   -> sLit "g";
                GE      -> sLit "ge";   GU    -> sLit "a";
                LTT     -> sLit "l";    LE    -> sLit "le";
                LEU     -> sLit "be";   NE    -> sLit "ne";
                NEG     -> sLit "s";    POS   -> sLit "ns";
                CARRY   -> sLit "c";   OFLO  -> sLit "o";
                PARITY  -> sLit "p";   NOTPARITY -> sLit "np";
                ALWAYS  -> sLit "mp"})


pprImm :: Imm -> SDoc
pprImm (ImmInt i)     = int i
pprImm (ImmInteger i) = integer i
pprImm (ImmCLbl l)    = ppr l
pprImm (ImmIndex l i) = ppr l <> char '+' <> int i
pprImm (ImmLit s)     = s

pprImm (ImmFloat _)  = text "naughty float immediate"
pprImm (ImmDouble _) = text "naughty double immediate"

pprImm (ImmConstantSum a b) = pprImm a <> char '+' <> pprImm b
pprImm (ImmConstantDiff a b) = pprImm a <> char '-'
                            <> lparen <> pprImm b <> rparen



pprAddr :: AddrMode -> SDoc
pprAddr (ImmAddr imm off)
  = let pp_imm = pprImm imm
    in
    if (off == 0) then
        pp_imm
    else if (off < 0) then
        pp_imm <> int off
    else
        pp_imm <> char '+' <> int off

pprAddr (AddrBaseIndex base index displacement)
  = sdocWithPlatform $ \platform ->
    let
        pp_disp  = ppr_disp displacement
        pp_off p = pp_disp <> char '(' <> p <> char ')'
        pp_reg r = pprReg (archWordFormat (target32Bit platform)) r
    in
    case (base, index) of
      (EABaseNone,  EAIndexNone) -> pp_disp
      (EABaseReg b, EAIndexNone) -> pp_off (pp_reg b)
      (EABaseRip,   EAIndexNone) -> pp_off (text "%rip")
      (EABaseNone,  EAIndex r i) -> pp_off (comma <> pp_reg r <> comma <> int i)
      (EABaseReg b, EAIndex r i) -> pp_off (pp_reg b <> comma <> pp_reg r
                                       <> comma <> int i)
      _                         -> panic "X86.Ppr.pprAddr: no match"

  where
    ppr_disp (ImmInt 0) = empty
    ppr_disp imm        = pprImm imm

-- | Print section header and appropriate alignment for that section.
pprSectionAlign :: Section -> SDoc
pprSectionAlign (Section (OtherSection _) _) =
     panic "X86.Ppr.pprSectionAlign: unknown section"
pprSectionAlign sec@(Section seg _) =
  sdocWithPlatform $ \platform ->
    pprSectionHeader platform sec $$
    pprAlignForSection seg

-- | Print appropriate alignment for the given section type.
pprAlignForSection :: SectionType -> SDoc
pprAlignForSection seg =
  sdocWithPlatform $ \platform ->
    text ".align " <>
    case platformOS platform of
      -- Darwin: alignments are given as shifts.
      OSDarwin
       | target32Bit platform ->
          case seg of
           ReadOnlyData16    -> int 4
           CString           -> int 1
           _                 -> int 2
       | otherwise ->
          case seg of
           ReadOnlyData16    -> int 4
           CString           -> int 1
           _                 -> int 3
      -- Other: alignments are given as bytes.
      _
       | target32Bit platform ->
          case seg of
           Text              -> text "4,0x90"
           ReadOnlyData16    -> int 16
           CString           -> int 1
           _                 -> int 4
       | otherwise ->
          case seg of
           ReadOnlyData16    -> int 16
           CString           -> int 1
           _                 -> int 8

pprDataItem :: CmmLit -> SDoc
pprDataItem lit = sdocWithDynFlags $ \dflags -> pprDataItem' dflags lit

pprDataItem' :: DynFlags -> CmmLit -> SDoc
pprDataItem' dflags lit
  = vcat (ppr_item (cmmTypeFormat $ cmmLitType dflags lit) lit)
    where
        platform = targetPlatform dflags
        imm = litToImm lit

        -- These seem to be common:
        ppr_item II8   _ = [text "\t.byte\t" <> pprImm imm]
        ppr_item II16  _ = [text "\t.word\t" <> pprImm imm]
        ppr_item II32  _ = [text "\t.long\t" <> pprImm imm]

        ppr_item FF32  (CmmFloat r _)
           = let bs = floatToBytes (fromRational r)
             in  map (\b -> text "\t.byte\t" <> pprImm (ImmInt b)) bs

        ppr_item FF64 (CmmFloat r _)
           = let bs = doubleToBytes (fromRational r)
             in  map (\b -> text "\t.byte\t" <> pprImm (ImmInt b)) bs

        ppr_item II64 _
            = case platformOS platform of
              OSDarwin
               | target32Bit platform ->
                  case lit of
                  CmmInt x _ ->
                      [text "\t.long\t"
                          <> int (fromIntegral (fromIntegral x :: Word32)),
                       text "\t.long\t"
                          <> int (fromIntegral
                              (fromIntegral (x `shiftR` 32) :: Word32))]
                  _ -> panic "X86.Ppr.ppr_item: no match for II64"
               | otherwise ->
                  [text "\t.quad\t" <> pprImm imm]
              _
               | target32Bit platform ->
                  [text "\t.quad\t" <> pprImm imm]
               | otherwise ->
                  -- x86_64: binutils can't handle the R_X86_64_PC64
                  -- relocation type, which means we can't do
                  -- pc-relative 64-bit addresses. Fortunately we're
                  -- assuming the small memory model, in which all such
                  -- offsets will fit into 32 bits, so we have to stick
                  -- to 32-bit offset fields and modify the RTS
                  -- appropriately
                  --
                  -- See Note [x86-64-relative] in includes/rts/storage/InfoTables.h
                  --
                  case lit of
                  -- A relative relocation:
                  CmmLabelDiffOff _ _ _ _ ->
                      [text "\t.long\t" <> pprImm imm,
                       text "\t.long\t0"]
                  _ ->
                      [text "\t.quad\t" <> pprImm imm]

        ppr_item _ _
                = panic "X86.Ppr.ppr_item: no match"


asmComment :: SDoc -> SDoc
asmComment c = whenPprDebug $ text "# " <> c

pprInstr :: Instr -> SDoc

pprInstr (COMMENT s)
   = asmComment (ftext s)

pprInstr (LOCATION file line col _name)
   = text "\t.loc " <> ppr file <+> ppr line <+> ppr col

pprInstr (DELTA d)
   = asmComment $ text ("\tdelta = " ++ show d)

pprInstr (NEWBLOCK _)
   = panic "PprMach.pprInstr: NEWBLOCK"

pprInstr (UNWIND lbl d)
   = asmComment (text "\tunwind = " <> ppr d)
     $$ ppr lbl <> colon

pprInstr (LDATA _ _)
   = panic "PprMach.pprInstr: LDATA"

{-
pprInstr (SPILL reg slot)
   = hcat [
        text "\tSPILL",
        char ' ',
        pprUserReg reg,
        comma,
        text "SLOT" <> parens (int slot)]

pprInstr (RELOAD slot reg)
   = hcat [
        text "\tRELOAD",
        char ' ',
        text "SLOT" <> parens (int slot),
        comma,
        pprUserReg reg]
-}

-- Replace 'mov $0x0,%reg' by 'xor %reg,%reg', which is smaller and cheaper.
-- The code generator catches most of these already, but not all.
pprInstr (MOV format (OpImm (ImmInt 0)) dst@(OpReg _))
  = pprInstr (XOR format' dst dst)
  where format' = case format of
          II64 -> II32          -- 32-bit version is equivalent, and smaller
          _    -> format
pprInstr (MOV format src dst)
  = pprFormatOpOp (sLit "mov") format src dst

pprInstr (CMOV cc format src dst)
  = pprCondOpReg (sLit "cmov") format cc src dst

pprInstr (MOVZxL II32 src dst) = pprFormatOpOp (sLit "mov") II32 src dst
        -- 32-to-64 bit zero extension on x86_64 is accomplished by a simple
        -- movl.  But we represent it as a MOVZxL instruction, because
        -- the reg alloc would tend to throw away a plain reg-to-reg
        -- move, and we still want it to do that.

pprInstr (MOVZxL formats src dst)
  = pprFormatOpOpCoerce (sLit "movz") formats II32 src dst
        -- zero-extension only needs to extend to 32 bits: on x86_64,
        -- the remaining zero-extension to 64 bits is automatic, and the 32-bit
        -- instruction is shorter.

pprInstr (MOVSxL formats src dst)
  = sdocWithPlatform $ \platform ->
    pprFormatOpOpCoerce (sLit "movs") formats (archWordFormat (target32Bit platform)) src dst

-- here we do some patching, since the physical registers are only set late
-- in the code generation.
pprInstr (LEA format (OpAddr (AddrBaseIndex (EABaseReg reg1) (EAIndex reg2 1) (ImmInt 0))) dst@(OpReg reg3))
  | reg1 == reg3
  = pprFormatOpOp (sLit "add") format (OpReg reg2) dst

pprInstr (LEA format (OpAddr (AddrBaseIndex (EABaseReg reg1) (EAIndex reg2 1) (ImmInt 0))) dst@(OpReg reg3))
  | reg2 == reg3
  = pprFormatOpOp (sLit "add") format (OpReg reg1) dst

pprInstr (LEA format (OpAddr (AddrBaseIndex (EABaseReg reg1) EAIndexNone displ)) dst@(OpReg reg3))
  | reg1 == reg3
  = pprInstr (ADD format (OpImm displ) dst)

pprInstr (LEA format src dst) = pprFormatOpOp (sLit "lea") format src dst

pprInstr (ADD format (OpImm (ImmInt (-1))) dst)
  = pprFormatOp (sLit "dec") format dst
pprInstr (ADD format (OpImm (ImmInt 1)) dst)
  = pprFormatOp (sLit "inc") format dst
pprInstr (ADD format src dst) = pprFormatOpOp (sLit "add") format src dst
pprInstr (ADC format src dst) = pprFormatOpOp (sLit "adc") format src dst
pprInstr (SUB format src dst) = pprFormatOpOp (sLit "sub") format src dst
pprInstr (SBB format src dst) = pprFormatOpOp (sLit "sbb") format src dst
pprInstr (IMUL format op1 op2) = pprFormatOpOp (sLit "imul") format op1 op2

pprInstr (ADD_CC format src dst)
  = pprFormatOpOp (sLit "add") format src dst
pprInstr (SUB_CC format src dst)
  = pprFormatOpOp (sLit "sub") format src dst

{- A hack.  The Intel documentation says that "The two and three
   operand forms [of IMUL] may also be used with unsigned operands
   because the lower half of the product is the same regardless if
   (sic) the operands are signed or unsigned.  The CF and OF flags,
   however, cannot be used to determine if the upper half of the
   result is non-zero."  So there.
-}

-- Use a 32-bit instruction when possible as it saves a byte.
-- Notably, extracting the tag bits of a pointer has this form.
-- TODO: we could save a byte in a subsequent CMP instruction too,
-- but need something like a peephole pass for this
pprInstr (AND II64 src@(OpImm (ImmInteger mask)) dst)
  | 0 <= mask && mask < 0xffffffff
    = pprInstr (AND II32 src dst)
pprInstr (AND FF32 src dst) = pprOpOp (sLit "andps") FF32 src dst
pprInstr (AND FF64 src dst) = pprOpOp (sLit "andpd") FF64 src dst
pprInstr (AND format src dst) = pprFormatOpOp (sLit "and") format src dst
pprInstr (OR  format src dst) = pprFormatOpOp (sLit "or")  format src dst

pprInstr (XOR FF32 src dst) = pprOpOp (sLit "xorps") FF32 src dst
pprInstr (XOR FF64 src dst) = pprOpOp (sLit "xorpd") FF64 src dst
pprInstr (XOR format src dst) = pprFormatOpOp (sLit "xor")  format src dst

pprInstr (POPCNT format src dst) = pprOpOp (sLit "popcnt") format src (OpReg dst)
pprInstr (LZCNT format src dst)  = pprOpOp (sLit "lzcnt")  format src (OpReg dst)
pprInstr (TZCNT format src dst)  = pprOpOp (sLit "tzcnt")  format src (OpReg dst)
pprInstr (BSF format src dst)    = pprOpOp (sLit "bsf")    format src (OpReg dst)
pprInstr (BSR format src dst)    = pprOpOp (sLit "bsr")    format src (OpReg dst)

pprInstr (PDEP format src mask dst)   = pprFormatOpOpReg (sLit "pdep") format src mask dst
pprInstr (PEXT format src mask dst)   = pprFormatOpOpReg (sLit "pext") format src mask dst

pprInstr (PREFETCH NTA format src ) = pprFormatOp_ (sLit "prefetchnta") format src
pprInstr (PREFETCH Lvl0 format src) = pprFormatOp_ (sLit "prefetcht0") format src
pprInstr (PREFETCH Lvl1 format src) = pprFormatOp_ (sLit "prefetcht1") format src
pprInstr (PREFETCH Lvl2 format src) = pprFormatOp_ (sLit "prefetcht2") format src

pprInstr (NOT format op) = pprFormatOp (sLit "not") format op
pprInstr (BSWAP format op) = pprFormatOp (sLit "bswap") format (OpReg op)
pprInstr (NEGI format op) = pprFormatOp (sLit "neg") format op

pprInstr (SHL format src dst) = pprShift (sLit "shl") format src dst
pprInstr (SAR format src dst) = pprShift (sLit "sar") format src dst
pprInstr (SHR format src dst) = pprShift (sLit "shr") format src dst

pprInstr (BT  format imm src) = pprFormatImmOp (sLit "bt") format imm src

pprInstr (CMP format src dst)
  | isFloatFormat format =  pprFormatOpOp (sLit "ucomi") format src dst -- SSE2
  | otherwise     =  pprFormatOpOp (sLit "cmp")   format src dst

pprInstr (TEST format src dst) = sdocWithPlatform $ \platform ->
  let format' = case (src,dst) of
        -- Match instructions like 'test $0x3,%esi' or 'test $0x7,%rbx'.
        -- We can replace them by equivalent, but smaller instructions
        -- by reducing the size of the immediate operand as far as possible.
        -- (We could handle masks larger than a single byte too,
        -- but it would complicate the code considerably
        -- and tag checks are by far the most common case.)
        -- The mask must have the high bit clear for this smaller encoding
        -- to be completely equivalent to the original; in particular so
        -- that the signed comparison condition bits are the same as they
        -- would be if doing a full word comparison. See #13425.
        (OpImm (ImmInteger mask), OpReg dstReg)
          | 0 <= mask && mask < 128 -> minSizeOfReg platform dstReg
        _ -> format
  in pprFormatOpOp (sLit "test") format' src dst
  where
    minSizeOfReg platform (RegReal (RealRegSingle i))
      | target32Bit platform && i <= 3        = II8  -- al, bl, cl, dl
      | target32Bit platform && i <= 7        = II16 -- si, di, bp, sp
      | not (target32Bit platform) && i <= 15 = II8  -- al .. r15b
    minSizeOfReg _ _ = format                 -- other

pprInstr (PUSH format op) = pprFormatOp (sLit "push") format op
pprInstr (POP format op) = pprFormatOp (sLit "pop") format op

-- both unused (SDM):
-- pprInstr PUSHA = text "\tpushal"
-- pprInstr POPA = text "\tpopal"

pprInstr NOP = text "\tnop"
pprInstr (CLTD II8) = text "\tcbtw"
pprInstr (CLTD II16) = text "\tcwtd"
pprInstr (CLTD II32) = text "\tcltd"
pprInstr (CLTD II64) = text "\tcqto"
pprInstr (CLTD x) = panic $ "pprInstr: " ++ show x

pprInstr (SETCC cond op) = pprCondInstr (sLit "set") cond (pprOperand II8 op)

pprInstr (JXX cond blockid)
  = pprCondInstr (sLit "j") cond (ppr lab)
  where lab = blockLbl blockid

pprInstr        (JXX_GBL cond imm) = pprCondInstr (sLit "j") cond (pprImm imm)

pprInstr        (JMP (OpImm imm) _) = text "\tjmp " <> pprImm imm
pprInstr (JMP op _)          = sdocWithPlatform $ \platform ->
                               text "\tjmp *"
                                   <> pprOperand (archWordFormat (target32Bit platform)) op
pprInstr (JMP_TBL op _ _ _)  = pprInstr (JMP op [])
pprInstr        (CALL (Left imm) _)    = text "\tcall " <> pprImm imm
pprInstr (CALL (Right reg) _)   = sdocWithPlatform $ \platform ->
                                  text "\tcall *"
                                      <> pprReg (archWordFormat (target32Bit platform)) reg

pprInstr (IDIV fmt op)   = pprFormatOp (sLit "idiv") fmt op
pprInstr (DIV fmt op)    = pprFormatOp (sLit "div")  fmt op
pprInstr (IMUL2 fmt op)  = pprFormatOp (sLit "imul") fmt op

-- x86_64 only
pprInstr (MUL format op1 op2) = pprFormatOpOp (sLit "mul") format op1 op2
pprInstr (MUL2 format op) = pprFormatOp (sLit "mul") format op

pprInstr (FDIV format op1 op2) = pprFormatOpOp (sLit "div") format op1 op2
pprInstr (SQRT format op1 op2) = pprFormatOpReg (sLit "sqrt") format op1 op2

pprInstr (CVTSS2SD from to)      = pprRegReg (sLit "cvtss2sd") from to
pprInstr (CVTSD2SS from to)      = pprRegReg (sLit "cvtsd2ss") from to
pprInstr (CVTTSS2SIQ fmt from to) = pprFormatFormatOpReg (sLit "cvttss2si") FF32 fmt from to
pprInstr (CVTTSD2SIQ fmt from to) = pprFormatFormatOpReg (sLit "cvttsd2si") FF64 fmt from to
pprInstr (CVTSI2SS fmt from to)   = pprFormatOpReg (sLit "cvtsi2ss") fmt from to
pprInstr (CVTSI2SD fmt from to)   = pprFormatOpReg (sLit "cvtsi2sd") fmt from to

    -- FETCHGOT for PIC on ELF platforms
pprInstr (FETCHGOT reg)
   = vcat [ text "\tcall 1f",
            hcat [ text "1:\tpopl\t", pprReg II32 reg ],
            hcat [ text "\taddl\t$_GLOBAL_OFFSET_TABLE_+(.-1b), ",
                   pprReg II32 reg ]
          ]

    -- FETCHPC for PIC on Darwin/x86
    -- get the instruction pointer into a register
    -- (Terminology note: the IP is called Program Counter on PPC,
    --  and it's a good thing to use the same name on both platforms)
pprInstr (FETCHPC reg)
   = vcat [ text "\tcall 1f",
            hcat [ text "1:\tpopl\t", pprReg II32 reg ]
          ]


-- the
-- GST fmt src addr ==> FLD dst ; FSTPsz addr
pprInstr g@(X87Store fmt  addr)
 = pprX87 g (hcat [gtab,
                 text "fstp", pprFormat_x87 fmt, gsp, pprAddr addr])


-- Atomics

pprInstr (LOCK i) = text "\tlock" $$ pprInstr i

pprInstr MFENCE = text "\tmfence"

pprInstr (XADD format src dst) = pprFormatOpOp (sLit "xadd") format src dst

pprInstr (CMPXCHG format src dst)
   = pprFormatOpOp (sLit "cmpxchg") format src dst



--------------------------
-- some left over



gtab :: SDoc
gtab  = char '\t'

gsp :: SDoc
gsp   = char ' '



pprX87 :: Instr -> SDoc -> SDoc
pprX87 fake actual
   = (char '#' <> pprX87Instr fake) $$ actual

pprX87Instr :: Instr -> SDoc
pprX87Instr (X87Store fmt  dst) = pprFormatAddr (sLit "gst") fmt  dst
pprX87Instr _ = panic "X86.Ppr.pprX87Instr: no match"

pprDollImm :: Imm -> SDoc
pprDollImm i = text "$" <> pprImm i


pprOperand :: Format -> Operand -> SDoc
pprOperand f (OpReg r)   = pprReg f r
pprOperand _ (OpImm i)   = pprDollImm i
pprOperand _ (OpAddr ea) = pprAddr ea


pprMnemonic_  :: PtrString -> SDoc
pprMnemonic_ name =
   char '\t' <> ptext name <> space


pprMnemonic  :: PtrString -> Format -> SDoc
pprMnemonic name format =
   char '\t' <> ptext name <> pprFormat format <> space


pprFormatImmOp :: PtrString -> Format -> Imm -> Operand -> SDoc
pprFormatImmOp name format imm op1
  = hcat [
        pprMnemonic name format,
        char '$',
        pprImm imm,
        comma,
        pprOperand format op1
    ]


pprFormatOp_ :: PtrString -> Format -> Operand -> SDoc
pprFormatOp_ name format op1
  = hcat [
        pprMnemonic_ name ,
        pprOperand format op1
    ]

pprFormatOp :: PtrString -> Format -> Operand -> SDoc
pprFormatOp name format op1
  = hcat [
        pprMnemonic name format,
        pprOperand format op1
    ]


pprFormatOpOp :: PtrString -> Format -> Operand -> Operand -> SDoc
pprFormatOpOp name format op1 op2
  = hcat [
        pprMnemonic name format,
        pprOperand format op1,
        comma,
        pprOperand format op2
    ]


pprOpOp :: PtrString -> Format -> Operand -> Operand -> SDoc
pprOpOp name format op1 op2
  = hcat [
        pprMnemonic_ name,
        pprOperand format op1,
        comma,
        pprOperand format op2
    ]



pprRegReg :: PtrString -> Reg -> Reg -> SDoc
pprRegReg name reg1 reg2
  = sdocWithPlatform $ \platform ->
    hcat [
        pprMnemonic_ name,
        pprReg (archWordFormat (target32Bit platform)) reg1,
        comma,
        pprReg (archWordFormat (target32Bit platform)) reg2
    ]


pprFormatOpReg :: PtrString -> Format -> Operand -> Reg -> SDoc
pprFormatOpReg name format op1 reg2
  = sdocWithPlatform $ \platform ->
    hcat [
        pprMnemonic name format,
        pprOperand format op1,
        comma,
        pprReg (archWordFormat (target32Bit platform)) reg2
    ]

pprCondOpReg :: PtrString -> Format -> Cond -> Operand -> Reg -> SDoc
pprCondOpReg name format cond op1 reg2
  = hcat [
        char '\t',
        ptext name,
        pprCond cond,
        space,
        pprOperand format op1,
        comma,
        pprReg format reg2
    ]

pprFormatFormatOpReg :: PtrString -> Format -> Format -> Operand -> Reg -> SDoc
pprFormatFormatOpReg name format1 format2 op1 reg2
  = hcat [
        pprMnemonic name format2,
        pprOperand format1 op1,
        comma,
        pprReg format2 reg2
    ]

pprFormatOpOpReg :: PtrString -> Format -> Operand -> Operand -> Reg -> SDoc
pprFormatOpOpReg name format op1 op2 reg3
  = hcat [
        pprMnemonic name format,
        pprOperand format op1,
        comma,
        pprOperand format op2,
        comma,
        pprReg format reg3
    ]



pprFormatAddr :: PtrString -> Format -> AddrMode -> SDoc
pprFormatAddr name format  op
  = hcat [
        pprMnemonic name format,
        comma,
        pprAddr op
    ]

pprShift :: PtrString -> Format -> Operand -> Operand -> SDoc
pprShift name format src dest
  = hcat [
        pprMnemonic name format,
        pprOperand II8 src,  -- src is 8-bit sized
        comma,
        pprOperand format dest
    ]


pprFormatOpOpCoerce :: PtrString -> Format -> Format -> Operand -> Operand -> SDoc
pprFormatOpOpCoerce name format1 format2 op1 op2
  = hcat [ char '\t', ptext name, pprFormat format1, pprFormat format2, space,
        pprOperand format1 op1,
        comma,
        pprOperand format2 op2
    ]


pprCondInstr :: PtrString -> Cond -> SDoc -> SDoc
pprCondInstr name cond arg
  = hcat [ char '\t', ptext name, pprCond cond, space, arg]