#
#
#           The Nimrod Compiler
#        (c) Copyright 2011 Andreas Rumpf
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

## This module implements the C code generator.

import 
  ast, astalgo, strutils, hashes, trees, platform, magicsys, extccomp,
  options, intsets,
  nversion, nimsets, msgs, crc, bitsets, idents, lists, types, ccgutils, os,
  times, ropes, math, passes, rodread, wordrecg, treetab, cgmeth,
  rodutils, renderer, idgen, cgendata, ccgmerge, semfold

when options.hasTinyCBackend:
  import tccgen

proc cgenPass*(): TPass
# implementation

proc ropeff(cformat, llvmformat: string, args: openarray[PRope]): PRope = 
  if gCmd == cmdCompileToLLVM: result = ropef(llvmformat, args)
  else: result = ropef(cformat, args)
  
proc appff(dest: var PRope, cformat, llvmformat: string, 
           args: openarray[PRope]) = 
  if gCmd == cmdCompileToLLVM: appf(dest, llvmformat, args)
  else: appf(dest, cformat, args)
  
proc addForwardedProc(m: BModule, prc: PSym) = 
  m.forwardedProcs.add(prc)
  inc(gForwardedProcsCounter)

proc addPendingModule(m: BModule) = 
  for i in countup(0, high(gPendingModules)): 
    if gPendingModules[i] == m: 
      InternalError("module already pending: " & m.module.name.s)
  gPendingModules.add(m)

proc findPendingModule(m: BModule, s: PSym): BModule = 
  var ms = getModule(s)
  if ms.id == m.module.id: return m
  for i in countup(0, high(gPendingModules)): 
    result = gPendingModules[i]
    if result.module.id == ms.id: return 
  # else we found no pending module: This can happen for procs that are in
  # a module that is already closed. This is fine, don't generate code for
  # it then:
  result = nil
  #InternalError(s.info, "no pending module found for: " & s.name.s)

proc emitLazily(s: PSym): bool {.inline.} =
  result = optDeadCodeElim in gGlobalOptions or
           sfDeadCodeElim in getModule(s).flags

proc initLoc(result: var TLoc, k: TLocKind, typ: PType, s: TStorageLoc) = 
  result.k = k
  result.s = s
  result.t = GetUniqueType(typ)
  result.r = nil
  result.a = - 1
  result.flags = {}

proc fillLoc(a: var TLoc, k: TLocKind, typ: PType, r: PRope, s: TStorageLoc) = 
  # fills the loc if it is not already initialized
  if a.k == locNone: 
    a.k = k
    a.t = getUniqueType(typ)
    a.a = - 1
    a.s = s
    if a.r == nil: a.r = r
  
proc isSimpleConst(typ: PType): bool =
  result = skipTypes(typ, abstractVar).kind notin
      {tyTuple, tyObject, tyArray, tyArrayConstr, tySet, tySequence}

proc useHeader(m: BModule, sym: PSym) = 
  if lfHeader in sym.loc.Flags: 
    assert(sym.annex != nil)
    discard lists.IncludeStr(m.headerFiles, getStr(sym.annex.path))

proc cgsym(m: BModule, name: string): PRope

proc ropecg(m: BModule, frmt: TFormatStr, args: openarray[PRope]): PRope = 
  var i = 0
  var length = len(frmt)
  result = nil
  var num = 0
  while i < length: 
    if frmt[i] == '$': 
      inc(i)                  # skip '$'
      case frmt[i]
      of '$': 
        app(result, "$")
        inc(i)
      of '#': 
        inc(i)
        app(result, args[num])
        inc(num)
      of '0'..'9': 
        var j = 0
        while true: 
          j = (j * 10) + Ord(frmt[i]) - ord('0')
          inc(i)
          if i >= length or not (frmt[i] in {'0'..'9'}): break 
        num = j
        if j > high(args) + 1: 
          internalError("ropes: invalid format string $" & $j)
        app(result, args[j-1])
      of 'n':
        if optLineDir notin gOptions: app(result, tnl)
        inc(i)
      of 'N': 
        app(result, tnl)
        inc(i)
      else: InternalError("ropes: invalid format string $" & frmt[i])
    elif frmt[i] == '#' and frmt[i+1] in IdentStartChars:
      inc(i)
      var j = i
      while frmt[j] in IdentChars: inc(j)
      var ident = substr(frmt, i, j-1)
      i = j
      app(result, cgsym(m, ident))
    elif frmt[i] == '#' and frmt[i+1] == '$':
      inc(i, 2)
      var j = 0
      while frmt[i] in Digits: 
        j = (j * 10) + Ord(frmt[i]) - ord('0')
        inc(i)
      app(result, cgsym(m, args[j-1].ropeToStr))
    var start = i
    while i < length: 
      if frmt[i] != '$' and frmt[i] != '#': inc(i)
      else: break 
    if i - 1 >= start: 
      app(result, substr(frmt, start, i - 1))

proc appcg(m: BModule, c: var PRope, frmt: TFormatStr, 
           args: openarray[PRope]) = 
  app(c, ropecg(m, frmt, args))

proc appcg(m: BModule, s: TCFileSection, frmt: TFormatStr, 
           args: openarray[PRope]) = 
  app(m.s[s], ropecg(m, frmt, args))

proc appcg(p: BProc, s: TCProcSection, frmt: TFormatStr, 
           args: openarray[PRope]) = 
  app(p.s[s], ropecg(p.module, frmt, args))

proc safeLineNm(info: TLineInfo): int =
  result = toLinenumber(info)
  if result < 0: result = 0 # negative numbers are not allowed in #line

proc genCLineDir(r: var PRope, filename: string, line: int) =
  assert line >= 0
  if optLineDir in gOptions:
    appff(r, "$N#line $2 $1$N", "; line $2 \"$1\"$n",
          [toRope(makeSingleLineCString(filename)), toRope(line)])

proc genCLineDir(r: var PRope, info: TLineInfo) = 
  genCLineDir(r, info.toFullPath, info.safeLineNm)

proc genLineDir(p: BProc, t: PNode) = 
  var line = t.info.safeLineNm
  genCLineDir(p.s[cpsStmts], t.info.toFullPath, line)
  if ({optStackTrace, optEndb} * p.Options == {optStackTrace, optEndb}) and
      (p.prc == nil or sfPure notin p.prc.flags): 
    appcg(p, cpsStmts, "#endb($1);$n", [toRope(line)])
  elif ({optLineTrace, optStackTrace} * p.Options ==
      {optLineTrace, optStackTrace}) and
      (p.prc == nil or sfPure notin p.prc.flags): 
    appf(p.s[cpsStmts], "F.line = $1;F.filename = $2;$n", 
        [toRope(line), makeCString(toFilename(t.info).extractFilename)])

include "ccgtypes.nim"

# ------------------------------ Manager of temporaries ------------------

proc rdLoc(a: TLoc): PRope =
  # 'read' location (deref if indirect)
  result = a.r
  if lfIndirect in a.flags: result = ropef("(*$1)", [result])

proc addrLoc(a: TLoc): PRope =
  result = a.r
  if lfIndirect notin a.flags and mapType(a.t) != ctArray: 
    result = con("&", result)

proc rdCharLoc(a: TLoc): PRope =
  # read a location that may need a char-cast:
  result = rdLoc(a)
  if skipTypes(a.t, abstractRange).kind == tyChar:
    result = ropef("((NU8)($1))", [result])

proc genObjectInit(p: BProc, section: TCProcSection, t: PType, a: TLoc, 
                   takeAddr: bool) =
  case analyseObjectWithTypeField(t)
  of frNone:
    nil
  of frHeader:
    var r = rdLoc(a)
    if not takeAddr: r = ropef("(*$1)", [r])
    var s = skipTypes(t, abstractInst)
    if gCmd != cmdCompileToCpp:
      while (s.kind == tyObject) and (s.sons[0] != nil):
        app(r, ".Sup")
        s = skipTypes(s.sons[0], abstractInst)
    appcg(p, section, "$1.m_type = $2;$n", [r, genTypeInfo(p.module, t)])
  of frEmbedded:
    # worst case for performance:
    var r = if takeAddr: addrLoc(a) else: rdLoc(a)
    appcg(p, section, "#objectInit($1, $2);$n", [r, genTypeInfo(p.module, t)])

type
  TAssignmentFlag = enum
    needToCopy, needForSubtypeCheck, afDestIsNil, afDestIsNotNil, afSrcIsNil,
    afSrcIsNotNil
  TAssignmentFlags = set[TAssignmentFlag]

proc genRefAssign(p: BProc, dest, src: TLoc, flags: TAssignmentFlags)

proc zeroVar(p: BProc, loc: TLoc, containsGCref: bool) = 
  if skipTypes(loc.t, abstractVarRange).Kind notin
      {tyArray, tyArrayConstr, tySet, tyTuple, tyObject}: 
    if containsGcref and p.WithInLoop > 0:
      appf(p.s[cpsInit], "$1 = 0;$n", [rdLoc(loc)])
      var nilLoc: TLoc
      initLoc(nilLoc, locTemp, loc.t, onStack)
      nilLoc.r = toRope("NIM_NIL")
      # puts ``unsureAsgnRef`` etc to ``p.s[cpsStmts]``:
      genRefAssign(p, loc, nilLoc, {afSrcIsNil})
    else:
      appf(p.s[cpsStmts], "$1 = 0;$n", [rdLoc(loc)])
  else: 
    if containsGcref and p.WithInLoop > 0:
      appf(p.s[cpsInit], "memset((void*)$1, 0, sizeof($2));$n", 
           [addrLoc(loc), rdLoc(loc)])
      appcg(p, cpsStmts, "#genericReset((void*)$1, $2);$n", 
           [addrLoc(loc), genTypeInfo(p.module, loc.t)])
    else:
      appf(p.s[cpsStmts], "memset((void*)$1, 0, sizeof($2));$n", 
           [addrLoc(loc), rdLoc(loc)])
    genObjectInit(p, cpsInit, loc.t, loc, true)

proc zeroTemp(p: BProc, loc: TLoc) = 
  if skipTypes(loc.t, abstractVarRange).Kind notin
      {tyArray, tyArrayConstr, tySet, tyTuple, tyObject}: 
    appf(p.s[cpsStmts], "$1 = 0;$n", [rdLoc(loc)])
    when false:
      var nilLoc: TLoc
      initLoc(nilLoc, locTemp, loc.t, onStack)
      nilLoc.r = toRope("NIM_NIL")
      # puts ``unsureAsgnRef`` etc to ``p.s[cpsStmts]``:
      genRefAssign(p, loc, nilLoc, {afSrcIsNil})
  else: 
    appf(p.s[cpsStmts], "memset((void*)$1, 0, sizeof($2));$n", 
         [addrLoc(loc), rdLoc(loc)])
    when false:
      appcg(p, cpsStmts, "#genericReset((void*)$1, $2);$n", 
           [addrLoc(loc), genTypeInfo(p.module, loc.t)])

proc initVariable(p: BProc, v: PSym) =
  if sfNoInit notin v.flags:
    var b = containsGarbageCollectedRef(v.typ)
    if b or v.ast == nil:
      zeroVar(p, v.loc, b)
    
proc initTemp(p: BProc, tmp: var TLoc) = 
  if containsGarbageCollectedRef(tmp.t) or isInvalidReturnType(tmp.t):
    zeroTemp(p, tmp)

proc getTemp(p: BProc, t: PType, result: var TLoc) = 
  inc(p.labels)
  if gCmd == cmdCompileToLLVM: 
    result.r = con("%LOC", toRope(p.labels))
  else: 
    result.r = con("LOC", toRope(p.labels))
    appf(p.s[cpsLocals], "$1 $2;$n", [getTypeDesc(p.module, t), result.r])
  result.k = locTemp
  result.a = - 1
  result.t = getUniqueType(t)
  result.s = OnStack
  result.flags = {}
  initTemp(p, result)

proc cstringLit(p: BProc, r: var PRope, s: string): PRope = 
  if gCmd == cmdCompileToLLVM: 
    inc(p.module.labels)
    inc(p.labels)
    result = ropef("%LOC$1", [toRope(p.labels)])
    appf(p.module.s[cfsData], "@C$1 = private constant [$2 x i8] $3$n", 
         [toRope(p.module.labels), toRope(len(s)), makeLLVMString(s)])
    appf(r, "$1 = getelementptr [$2 x i8]* @C$3, %NI 0, %NI 0$n", 
         [result, toRope(len(s)), toRope(p.module.labels)])
  else: 
    result = makeCString(s)
  
proc cstringLit(m: BModule, r: var PRope, s: string): PRope = 
  if gCmd == cmdCompileToLLVM: 
    inc(m.labels, 2)
    result = ropef("%MOC$1", [toRope(m.labels - 1)])
    appf(m.s[cfsData], "@MOC$1 = private constant [$2 x i8] $3$n", 
         [toRope(m.labels), toRope(len(s)), makeLLVMString(s)])
    appf(r, "$1 = getelementptr [$2 x i8]* @MOC$3, %NI 0, %NI 0$n", 
         [result, toRope(len(s)), toRope(m.labels)])
  else: 
    result = makeCString(s)
  
proc allocParam(p: BProc, s: PSym) = 
  assert(s.kind == skParam)
  if lfParamCopy notin s.loc.flags: 
    inc(p.labels)
    var tmp = con("%LOC", toRope(p.labels))
    incl(s.loc.flags, lfParamCopy)
    incl(s.loc.flags, lfIndirect)
    appf(p.s[cpsInit], "$1 = alloca $3$n" & "store $3 $2, $3* $1$n", 
         [tmp, s.loc.r, getTypeDesc(p.module, s.loc.t)])
    s.loc.r = tmp

proc localDebugInfo(p: BProc, s: PSym) = 
  if {optStackTrace, optEndb} * p.options != {optStackTrace, optEndb}: return 
  # XXX work around a bug: No type information for open arrays possible:
  if skipTypes(s.typ, abstractVar).kind == tyOpenArray: return
  var a = con("&", s.loc.r)
  if (s.kind == skParam) and ccgIntroducedPtr(s): a = s.loc.r
  appf(p.s[cpsInit], 
       "F.s[$1].address = (void*)$3; F.s[$1].typ = $4; F.s[$1].name = $2;$n",
       [toRope(p.frameLen), makeCString(normalize(s.name.s)), a, 
        genTypeInfo(p.module, s.loc.t)])
  inc(p.frameLen)

proc assignLocalVar(p: BProc, s: PSym) = 
  #assert(s.loc.k == locNone) // not yet assigned
  # this need not be fullfilled for inline procs; they are regenerated
  # for each module that uses them!
  if s.loc.k == locNone: 
    fillLoc(s.loc, locLocalVar, s.typ, mangleName(s), OnStack)
  app(p.s[cpsLocals], getTypeDesc(p.module, s.loc.t))
  if sfRegister in s.flags: app(p.s[cpsLocals], " register")
  if (sfVolatile in s.flags) or (p.nestedTryStmts.len > 0): 
    app(p.s[cpsLocals], " volatile")
  appf(p.s[cpsLocals], " $1;$n", [s.loc.r])
  localDebugInfo(p, s)

include ccgthreadvars

proc assignGlobalVar(p: BProc, s: PSym) = 
  if s.loc.k == locNone: 
    fillLoc(s.loc, locGlobalVar, s.typ, mangleName(s), OnHeap)
  useHeader(p.module, s)
  if lfNoDecl in s.loc.flags: return
  if sfThread in s.flags: 
    declareThreadVar(p.module, s, sfImportc in s.flags)
  else: 
    if sfImportc in s.flags: app(p.module.s[cfsVars], "extern ")
    app(p.module.s[cfsVars], getTypeDesc(p.module, s.loc.t))
    if sfRegister in s.flags: app(p.module.s[cfsVars], " register")
    if sfVolatile in s.flags: app(p.module.s[cfsVars], " volatile")
    appf(p.module.s[cfsVars], " $1;$n", [s.loc.r])
  if p.module.module.options * {optStackTrace, optEndb} ==
                               {optStackTrace, optEndb}: 
    appcg(p.module, p.module.s[cfsDebugInit], 
          "#dbgRegisterGlobal($1, &$2, $3);$n", 
         [cstringLit(p, p.module.s[cfsDebugInit], 
          normalize(s.owner.name.s & '.' & s.name.s)), 
          s.loc.r, genTypeInfo(p.module, s.typ)])
  
proc assignParam(p: BProc, s: PSym) = 
  assert(s.loc.r != nil)
  if sfAddrTaken in s.flags and gCmd == cmdCompileToLLVM: allocParam(p, s)
  localDebugInfo(p, s)

proc fillProcLoc(sym: PSym) = 
  if sym.loc.k == locNone: 
    fillLoc(sym.loc, locProc, sym.typ, mangleName(sym), OnStack)
  
proc getLabel(p: BProc): TLabel = 
  inc(p.labels)
  result = con("LA", toRope(p.labels))

proc fixLabel(p: BProc, labl: TLabel) = 
  appf(p.s[cpsStmts], "$1: ;$n", [labl])

proc genVarPrototype(m: BModule, sym: PSym)
proc requestConstImpl(p: BProc, sym: PSym)
proc genProc(m: BModule, prc: PSym)
proc genStmts(p: BProc, t: PNode)
proc genProcPrototype(m: BModule, sym: PSym)

include "ccgexprs.nim", "ccgstmts.nim"

# ----------------------------- dynamic library handling -----------------
# We don't finalize dynamic libs as this does the OS for us.

proc libCandidates(s: string, dest: var TStringSeq) = 
  var le = strutils.find(s, '(')
  var ri = strutils.find(s, ')', le+1)
  if le >= 0 and ri > le: 
    var prefix = substr(s, 0, le - 1)
    var suffix = substr(s, ri + 1)
    for middle in split(substr(s, le + 1, ri - 1), '|'):
      libCandidates(prefix & middle & suffix, dest)
  else: 
    add(dest, s)

proc loadDynamicLib(m: BModule, lib: PLib) = 
  assert(lib != nil)
  if not lib.generated: 
    lib.generated = true
    var tmp = getGlobalTempName()
    assert(lib.name == nil)
    lib.name = tmp # BUGFIX: cgsym has awful side-effects
    appf(m.s[cfsVars], "static void* $1;$n", [tmp])
    if lib.path.kind in {nkStrLit..nkTripleStrLit}:
      var s: TStringSeq = @[]
      libCandidates(lib.path.strVal, s)
      var loadlib: PRope = nil
      for i in countup(0, high(s)): 
        inc(m.labels)
        if i > 0: app(loadlib, "||")
        appcg(m, loadlib, "($1 = #nimLoadLibrary((#NimStringDesc*) &$2))$n", 
              [tmp, getStrLit(m, s[i])])
      appcg(m, m.s[cfsDynLibInit], 
            "if (!($1)) #nimLoadLibraryError((#NimStringDesc*) &$2);$n", 
            [loadlib, getStrLit(m, lib.path.strVal)]) 
    else:
      var p = newProc(nil, m)
      var dest: TLoc
      initLocExpr(p, lib.path, dest)
      app(m.s[cfsVars], p.s[cpsLocals])
      app(m.s[cfsDynLibInit], p.s[cpsInit])
      app(m.s[cfsDynLibInit], p.s[cpsStmts])
      appcg(m, m.s[cfsDynLibInit], 
           "if (!($1 = #nimLoadLibrary($2))) #nimLoadLibraryError($2);$n", 
           [tmp, rdLoc(dest)])
      
  if lib.name == nil: InternalError("loadDynamicLib")
  
proc mangleDynLibProc(sym: PSym): PRope =
  if sfCompilerProc in sym.flags: 
    # NOTE: sym.loc.r is the external name!
    result = toRope(sym.name.s)
  else:
    result = ropef("Dl_$1", [toRope(sym.id)])
  
proc SymInDynamicLib(m: BModule, sym: PSym) = 
  var lib = sym.annex
  var extname = sym.loc.r
  loadDynamicLib(m, lib)
  if gCmd == cmdCompileToLLVM: incl(sym.loc.flags, lfIndirect)
  var tmp = mangleDynLibProc(sym)
  sym.loc.r = tmp             # from now on we only need the internal name
  sym.typ.sym = nil           # generate a new name
  inc(m.labels, 2)
  appcg(m, m.s[cfsDynLibInit], 
      "$1 = ($2) #nimGetProcAddr($3, $4);$n", 
      [tmp, getTypeDesc(m, sym.typ), 
      lib.name, cstringLit(m, m.s[cfsDynLibInit], ropeToStr(extname))])
  appff(m.s[cfsVars], "$2 $1;$n", 
      "$1 = linkonce global $2 zeroinitializer$n", 
      [sym.loc.r, getTypeDesc(m, sym.loc.t)])

proc SymInDynamicLibPartial(m: BModule, sym: PSym) =
  sym.loc.r = mangleDynLibProc(sym)
  sym.typ.sym = nil           # generate a new name

proc cgsym(m: BModule, name: string): PRope = 
  var sym = magicsys.getCompilerProc(name)
  if sym != nil: 
    case sym.kind
    of skProc, skMethod, skConverter: genProc(m, sym)
    of skVar, skResult: genVarPrototype(m, sym)
    of skType: discard getTypeDesc(m, sym.typ)
    else: InternalError("cgsym: " & name)
  else:
    # we used to exclude the system module from this check, but for DLL
    # generation support this sloppyness leads to hard to detect bugs, so
    # we're picky here for the system module too:
    rawMessage(errSystemNeeds, name)
  result = sym.loc.r
  
proc generateHeaders(m: BModule) = 
  app(m.s[cfsHeaders], tnl & "#include \"nimbase.h\"" & tnl)
  var it = PStrEntry(m.headerFiles.head)
  while it != nil: 
    if it.data[0] notin {'\"', '<'}: 
      appf(m.s[cfsHeaders], "$N#include \"$1\"$N", [toRope(it.data)])
    else: 
      appf(m.s[cfsHeaders], "$N#include $1$N", [toRope(it.data)])
    it = PStrEntry(it.Next)

proc getFrameDecl(p: BProc) = 
  var slots: PRope
  if p.frameLen > 0: 
    discard cgsym(p.module, "TVarSlot")
    slots = ropeff("  TVarSlot s[$1];$n", ", [$1 x %TVarSlot]", 
                   [toRope(p.frameLen)])
  else: 
    slots = nil
  appff(p.s[cpsLocals], "volatile struct {TFrame* prev;" &
      "NCSTRING procname;NI line;NCSTRING filename;" & 
      "NI len;$n$1} F;$n", 
      "%TF = type {%TFrame*, i8*, %NI, %NI$1}$n" & 
      "%F = alloca %TF$n", [slots])
  inc(p.labels)
  prepend(p.s[cpsInit], ropeff("F.len = $1;$n", 
      "%LOC$2 = getelementptr %TF %F, %NI 4$n" &
      "store %NI $1, %NI* %LOC$2$n", [toRope(p.frameLen), toRope(p.labels)]))

proc retIsNotVoid(s: PSym): bool = 
  result = (s.typ.sons[0] != nil) and not isInvalidReturnType(s.typ.sons[0])

proc initFrame(p: BProc, procname, filename: PRope): PRope = 
  result = ropecg(p.module, 
    "F.procname = $1;$n" &
    "F.filename = $2;$n" & 
    "F.line = 0;$n" & 
    "#pushFrame((TFrame*)&F);$n", [procname, filename])

proc deinitFrame(p: BProc): PRope =
  result = ropecg(p.module, "#popFrame();$n")

proc genProcAux(m: BModule, prc: PSym) =
  var p = newProc(prc, m)
  var header = genProcHeader(m, prc)
  if gCmd != cmdCompileToLLVM and lfExportLib in prc.loc.flags: 
    header = con("N_LIB_EXPORT ", header)
  var returnStmt: PRope = nil
  assert(prc.ast != nil)
  if sfPure notin prc.flags and prc.typ.sons[0] != nil:
    var res = prc.ast.sons[resultPos].sym # get result symbol
    if not isInvalidReturnType(prc.typ.sons[0]): 
      # declare the result symbol:
      assignLocalVar(p, res)
      assert(res.loc.r != nil)
      returnStmt = ropeff("return $1;$n", "ret $1$n", [rdLoc(res.loc)])
      initVariable(p, res)
    else: 
      fillResult(res)
      assignParam(p, res)
      if skipTypes(res.typ, abstractInst).kind == tyArray: 
        incl(res.loc.flags, lfIndirect)
        res.loc.s = OnUnknown
  for i in countup(1, sonsLen(prc.typ.n) - 1): 
    var param = prc.typ.n.sons[i].sym
    assignParam(p, param)
  genStmts(p, prc.getBody) # modifies p.locals, p.init, etc.
  var generatedProc: PRope
  if sfPure in prc.flags: 
    generatedProc = ropeff("$1 {$n$2$3$4}$n", "define $1 {$n$2$3$4}$n",
        [header, p.s[cpsLocals], p.s[cpsInit], p.s[cpsStmts]])
  else: 
    generatedProc = ropeff("$1 {$n", "define $1 {$n", [header])
    if optStackTrace in prc.options: 
      getFrameDecl(p)
      app(generatedProc, p.s[cpsLocals])
      var procname = CStringLit(p, generatedProc, prc.name.s)
      var filename = CStringLit(p, generatedProc, toFilename(prc.info))
      app(generatedProc, initFrame(p, procname, filename))
    else: 
      app(generatedProc, p.s[cpsLocals])
    if (optProfiler in prc.options) and (gCmd != cmdCompileToLLVM): 
      if gProcProfile >= 64 * 1024: 
        InternalError(prc.info, "too many procedures for profiling")
      discard cgsym(m, "profileData")
      appf(p.s[cpsLocals], "ticks NIM_profilingStart;$n")
      if prc.loc.a < 0: 
        appf(m.s[cfsDebugInit], "profileData[$1].procname = $2;$n", [
            toRope(gProcProfile), 
            makeCString(prc.name.s)])
        prc.loc.a = gProcProfile
        inc(gProcProfile)
      prepend(p.s[cpsInit], ropef("NIM_profilingStart = getticks();$n"))
    app(generatedProc, p.s[cpsInit])
    app(generatedProc, p.s[cpsStmts])
    if p.beforeRetNeeded: appf(generatedProc, "BeforeRet: $n;")
    if optStackTrace in prc.options: app(generatedProc, deinitFrame(p))
    if (optProfiler in prc.options) and (gCmd != cmdCompileToLLVM): 
      appf(generatedProc, 
        "profileData[$1].total += elapsed(getticks(), NIM_profilingStart);$n", 
        [toRope(prc.loc.a)])
    app(generatedProc, returnStmt)
    appf(generatedProc, "}$n")
  app(m.s[cfsProcs], generatedProc)
  
proc genProcPrototype(m: BModule, sym: PSym) = 
  useHeader(m, sym)
  if lfNoDecl in sym.loc.Flags: return 
  if lfDynamicLib in sym.loc.Flags:
    if sym.owner.id != m.module.id and
        not ContainsOrIncl(m.declaredThings, sym.id): 
      appf(m.s[cfsVars], "extern $1 $2;$n", 
           [getTypeDesc(m, sym.loc.t), mangleDynLibProc(sym)])
      if gCmd == cmdCompileToLLVM: incl(sym.loc.flags, lfIndirect)
  elif not ContainsOrIncl(m.declaredProtos, sym.id): 
    appf(m.s[cfsProcHeaders], "$1;$n", [genProcHeader(m, sym)])

proc genProcNoForward(m: BModule, prc: PSym) = 
  fillProcLoc(prc)
  useHeader(m, prc)
  if lfImportCompilerProc in prc.loc.flags:
    # dependency to a compilerproc:
    discard cgsym(m, prc.name.s)
    return  
  genProcPrototype(m, prc)  
  if lfNoDecl in prc.loc.Flags: nil
  elif prc.typ.callConv == ccInline:
    # We add inline procs to the calling module to enable C based inlining.
    # This also means that a check with ``q.declaredThings`` is wrong, we need
    # a check for ``m.declaredThings``.
    if not ContainsOrIncl(m.declaredThings, prc.id): genProcAux(m, prc)
  elif lfDynamicLib in prc.loc.flags:
    var q = findPendingModule(m, prc)
    if q != nil and not ContainsOrIncl(q.declaredThings, prc.id): 
      SymInDynamicLib(q, prc)
    else:
      SymInDynamicLibPartial(m, prc)
  elif sfImportc notin prc.flags:
    var q = findPendingModule(m, prc)
    if q != nil and not ContainsOrIncl(q.declaredThings, prc.id): 
      genProcAux(q, prc)

proc requestConstImpl(p: BProc, sym: PSym) =
  var m = p.module
  useHeader(m, sym)
  if sym.loc.k == locNone:
    fillLoc(sym.loc, locData, sym.typ, mangleName(sym), OnUnknown)
  if lfNoDecl in sym.loc.Flags: return
  # declare implementation:
  var q = findPendingModule(m, sym)
  if q != nil and not ContainsOrIncl(q.declaredThings, sym.id):
    assert q.initProc.module == q
    appf(q.s[cfsData], "NIM_CONST $1 $2 = $3;$n",
        [getTypeDesc(q, sym.typ), sym.loc.r, genConstExpr(q.initProc, sym.ast)])
  # declare header:
  if q != m and not ContainsOrIncl(m.declaredThings, sym.id):
    assert(sym.loc.r != nil)
    appf(m.s[cfsData], "extern NIM_CONST $1 $2;$n",
        [getTypeDesc(m, sym.loc.t), sym.loc.r])

proc genProc(m: BModule, prc: PSym) = 
  if sfBorrow in prc.flags: return 
  fillProcLoc(prc)
  if {sfForward, sfFromGeneric} * prc.flags != {}: addForwardedProc(m, prc)
  else: genProcNoForward(m, prc)
  
proc genVarPrototype(m: BModule, sym: PSym) = 
  assert(sfGlobal in sym.flags)
  useHeader(m, sym)
  fillLoc(sym.loc, locGlobalVar, sym.typ, mangleName(sym), OnHeap)
  if (lfNoDecl in sym.loc.Flags) or ContainsOrIncl(m.declaredThings, sym.id): 
    return 
  if sym.owner.id != m.module.id: 
    # else we already have the symbol generated!
    assert(sym.loc.r != nil)
    if sfThread in sym.flags: 
      declareThreadVar(m, sym, true)
    else:
      app(m.s[cfsVars], "extern ")
      app(m.s[cfsVars], getTypeDesc(m, sym.loc.t))
      if sfRegister in sym.flags: app(m.s[cfsVars], " register")
      if sfVolatile in sym.flags: app(m.s[cfsVars], " volatile")
      appf(m.s[cfsVars], " $1;$n", [sym.loc.r])

proc getFileHeader(cfilenoext: string): PRope = 
  if optCompileOnly in gGlobalOptions: 
    result = ropeff("/* Generated by Nimrod Compiler v$1 */$n" &
        "/*   (c) 2011 Andreas Rumpf */$n", 
        "; Generated by Nimrod Compiler v$1$n" &
        ";   (c) 2011 Andreas Rumpf$n", [toRope(versionAsString)])
  else: 
    result = ropeff("/* Generated by Nimrod Compiler v$1 */$n" &
        "/*   (c) 2011 Andreas Rumpf */$n" & 
        "/* Compiled for: $2, $3, $4 */$n" &
        "/* Command for C compiler:$n   $5 */$n", 
        "; Generated by Nimrod Compiler v$1$n" &
        ";   (c) 2011 Andreas Rumpf$n" & 
        "; Compiled for: $2, $3, $4$n" &
        "; Command for LLVM compiler:$n   $5$n", [toRope(versionAsString), 
        toRope(platform.OS[targetOS].name), 
        toRope(platform.CPU[targetCPU].name), 
        toRope(extccomp.CC[extccomp.ccompiler].name), 
        toRope(getCompileCFileCmd(cfilenoext))])
  case platform.CPU[targetCPU].intSize
  of 16: 
    appff(result, 
          "$ntypedef short int NI;$n" & "typedef unsigned short int NU;$n", 
          "$n%NI = type i16$n", [])
  of 32: 
    appff(result, 
          "$ntypedef long int NI;$n" & "typedef unsigned long int NU;$n", 
          "$n%NI = type i32$n", [])
  of 64: 
    appff(result, "$ntypedef long long int NI;$n" &
        "typedef unsigned long long int NU;$n", "$n%NI = type i64$n", [])
  else: 
    nil

proc genMainProc(m: BModule) = 
  const 
    CommonMainBody = 
        "  nim__datInit();$n" &
        "  systemInit();$n" & 
        "$1" & 
        "$2"
    PosixNimMain = 
        "int cmdCount;$n" & 
        "char** cmdLine;$n" & 
        "char** gEnv;$n" &
        "N_CDECL(void, NimMain)(void) {$n" &
        CommonMainBody & "}$n"
    PosixCMain = "int main(int argc, char** args, char** env) {$n" &
        "  cmdLine = args;$n" & "  cmdCount = argc;$n" & "  gEnv = env;$n" &
        "  NimMain();$n" & "  return nim_program_result;$n" & "}$n"
    WinNimMain = "N_CDECL(void, NimMain)(void) {$n" &
        CommonMainBody & "}$n"
    WinCMain = "N_STDCALL(int, WinMain)(HINSTANCE hCurInstance, $n" &
        "                        HINSTANCE hPrevInstance, $n" &
        "                        LPSTR lpCmdLine, int nCmdShow) {$n" &
        "  NimMain();$n" & "  return nim_program_result;$n" & "}$n"
    WinNimDllMain = "N_LIB_EXPORT N_CDECL(void, NimMain)(void) {$n" &
        CommonMainBody & "}$n"
    WinCDllMain = 
        "BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fwdreason, $n" &
        "                    LPVOID lpvReserved) {$n" & "  NimMain();$n" &
        "  return 1;$n" & "}$n"
    PosixNimDllMain = WinNimDllMain
    PosixCDllMain = 
        "void NIM_POSIX_INIT NimMainInit(void) {$n" &
        "  NimMain();$n}$n"
  var nimMain, otherMain: TFormatStr
  if platform.targetOS == osWindows and
      gGlobalOptions * {optGenGuiApp, optGenDynLib} != {}: 
    if optGenGuiApp in gGlobalOptions: 
      nimMain = WinNimMain
      otherMain = WinCMain
    else: 
      nimMain = WinNimDllMain
      otherMain = WinCDllMain
    discard lists.IncludeStr(m.headerFiles, "<windows.h>")
  elif optGenDynLib in gGlobalOptions:
    nimMain = posixNimDllMain
    otherMain = posixCDllMain
  else: 
    nimMain = PosixNimMain
    otherMain = PosixCMain
  if gBreakpoints != nil: discard cgsym(m, "dbgRegisterBreakpoint")
  inc(m.labels)
  appcg(m, m.s[cfsProcs], nimMain, [
        gBreakpoints, mainModInit, toRope(m.labels)])
  if not (optNoMain in gGlobalOptions): 
    appcg(m, m.s[cfsProcs], otherMain, [])
  
proc getInitName(m: PSym): PRope = 
  result = ropeff("$1Init", "@$1Init", [toRope(m.name.s)])

proc registerModuleToMain(m: PSym) = 
  var initname = getInitName(m)
  appff(mainModProcs, "N_NOINLINE(void, $1)(void);$n", 
        "declare void $1() noinline$n", [initname])
  if not (sfSystemModule in m.flags): 
    appff(mainModInit, "$1();$n", "call void ()* $1$n", [initname])
  
proc genInitCode(m: BModule) = 
  if optProfiler in m.initProc.options: 
    # This does not really belong here, but there is no good place for this
    # code. I don't want to put this to the proc generation as the
    # ``IncludeStr`` call is quite slow.
    discard lists.IncludeStr(m.headerFiles, "<cycle.h>")
  var initname = getInitName(m.module)
  var prc = ropeff("N_NOINLINE(void, $1)(void) {$n", 
                   "define void $1() noinline {$n", [initname])
  if m.typeNodes > 0: 
    appcg(m, m.s[cfsTypeInit1], "static #TNimNode $1[$2];$n", 
          [m.typeNodesName, toRope(m.typeNodes)])
  if m.nimTypes > 0: 
    appcg(m, m.s[cfsTypeInit1], "static #TNimType $1[$2];$n", 
          [m.nimTypesName, toRope(m.nimTypes)])
  if optStackTrace in m.initProc.options and not m.FrameDeclared:
    # BUT: the generated init code might depend on a current frame, so
    # declare it nevertheless:
    m.FrameDeclared = true
    getFrameDecl(m.initProc)
  
  app(prc, genSectionStart(cpsLocals))
  app(prc, m.initProc.s[cpsLocals])
  app(prc, genSectionEnd(cpsLocals))

  app(prc, genSectionStart(cfsTypeInit1))
  app(prc, m.s[cfsTypeInit1])
  if optStackTrace in m.initProc.options and not m.PreventStackTrace: 
    var procname = CStringLit(m.initProc, prc, m.module.name.s)
    var filename = CStringLit(m.initProc, prc, toFilename(m.module.info))
    app(prc, initFrame(m.initProc, procname, filename))
  app(prc, genSectionEnd(cfsTypeInit1))
  
  for i in cfsTypeInit2..cfsDynLibInit:
    app(prc, genSectionStart(i))
    app(prc, m.s[i])
    app(prc, genSectionEnd(i))
  
  app(prc, genSectionStart(cpsInit))
  app(prc, m.initProc.s[cpsInit])
  app(prc, genSectionEnd(cpsInit))

  app(prc, genSectionStart(cpsStmts))  
  app(prc, m.initProc.s[cpsStmts])
  if optStackTrace in m.initProc.options and not m.PreventStackTrace:
    app(prc, deinitFrame(m.initProc))
  app(prc, genSectionEnd(cpsStmts))
  appf(prc, "}$n$n")
  # we cannot simply add the init proc to ``m.s[cfsProcs]`` anymore because
  # that would lead to a *nesting* of merge sections which the merger does
  # not support. So we add it to another special section: ``cfsInitProc``
  app(m.s[cfsInitProc], prc)

proc genModule(m: BModule, cfilenoext: string): PRope = 
  result = getFileHeader(cfilenoext)
  result.app(genMergeInfo(m))
  
  generateHeaders(m)

  generateThreadLocalStorage(m)
  for i in countup(cfsHeaders, cfsProcs): 
    app(result, genSectionStart(i))
    app(result, m.s[i])
    app(result, genSectionEnd(i))
  app(result, m.s[cfsInitProc])
  
proc rawNewModule(module: PSym, filename: string): BModule = 
  new(result)
  InitLinkedList(result.headerFiles)
  result.declaredThings = initIntSet()
  result.declaredProtos = initIntSet()
  result.cfilename = filename
  result.filename = filename
  initIdTable(result.typeCache)
  initIdTable(result.forwTypeCache)
  result.module = module
  result.typeInfoMarker = initIntSet()
  result.initProc = newProc(nil, result)
  result.initProc.options = gOptions
  initNodeTable(result.dataCache)
  result.typeStack = @[]
  result.forwardedProcs = @[]
  result.typeNodesName = getTempName()
  result.nimTypesName = getTempName()
  result.PreventStackTrace = sfSystemModule in module.flags

proc newModule(module: PSym, filename: string): BModule = 
  result = rawNewModule(module, filename)
  if (optDeadCodeElim in gGlobalOptions): 
    if (sfDeadCodeElim in module.flags): 
      InternalError("added pending module twice: " & filename)
    addPendingModule(result)

proc registerTypeInfoModule() = 
  const moduleName = "nim__dat"
  var s = NewSym(skModule, getIdent(moduleName), nil)
  gNimDat = rawNewModule(s, (options.projectPath / moduleName) & ".nim")
  gNimDat.PreventStackTrace = true
  addPendingModule(gNimDat)
  appff(mainModProcs, "N_NOINLINE(void, $1)(void);$n", 
        "declare void $1() noinline$n", [getInitName(s)])

proc myOpen(module: PSym, filename: string): PPassContext = 
  if gNimDat == nil: registerTypeInfoModule()
  result = newModule(module, filename)

proc getCFile(m: BModule): string =
  result = changeFileExt(completeCFilePath(m.cfilename), cExt)

proc myOpenCached(module: PSym, filename: string, 
                  rd: PRodReader): PPassContext = 
  if gNimDat == nil:
    registerTypeInfoModule()
    gNimDat.fromCache = true
    readMergeInfo(getCFile(gNimDat), gNimDat)
    
  var m = newModule(module, filename)
  readMergeInfo(getCFile(m), m)
  result = m

proc myProcess(b: PPassContext, n: PNode): PNode = 
  result = n
  if b == nil or passes.skipCodegen(n): return
  var m = BModule(b)
  m.initProc.options = gOptions
  genStmts(m.initProc, n)

proc finishModule(m: BModule) = 
  var i = 0
  while i <= high(m.forwardedProcs): 
    # Note: ``genProc`` may add to ``m.forwardedProcs``, so we cannot use
    # a ``for`` loop here
    var prc = m.forwardedProcs[i]
    if sfForward in prc.flags: 
      InternalError(prc.info, "still forwarded: " & prc.name.s)
    genProcNoForward(m, prc)
    inc(i)
  assert(gForwardedProcsCounter >= i)
  dec(gForwardedProcsCounter, i)
  setlen(m.forwardedProcs, 0)

proc shouldRecompile(code: PRope, cfile, cfilenoext: string): bool = 
  result = true
  if optForceFullMake notin gGlobalOptions:
    var objFile = toObjFile(cfilenoext)
    if writeRopeIfNotEqual(code, cfile): return 
    if ExistsFile(objFile) and os.FileNewer(objFile, cfile): result = false
  else: 
    writeRope(code, cfile)

# We need 2 different logics here: pending modules (including
# 'nim__dat') may require file merging for the combination of dead code
# elimination and incremental compilation! Non pending modules need no
# such logic and in fact the logic hurts for the main module at least;
# it would generate multiple 'main' procs, for instance.

proc writeModule(m: BModule, pending: bool) =
  # generate code for the init statements of the module:
  var cfile = getCFile(m)
  var cfilenoext = changeFileExt(cfile, "")
  
  if not m.fromCache or optForceFullMake in gGlobalOptions:
    genInitCode(m)
    finishTypeDescriptions(m)
    if sfMainModule in m.module.flags: 
      # generate main file:
      app(m.s[cfsProcHeaders], mainModProcs)
      GenerateThreadVarsSize(m)
    
    var code = genModule(m, cfilenoext)
    when hasTinyCBackend:
      if gCmd == cmdRun:
        tccgen.compileCCode(ropeToStr(code))
        return

    if shouldRecompile(code, cfile, cfilenoext):
      addFileToCompile(cfilenoext)
  elif pending and mergeRequired(m) and sfMainModule notin m.module.flags:
    mergeFiles(cfile, m)
    genInitCode(m)
    finishTypeDescriptions(m)
    var code = genModule(m, cfilenoext)
    writeRope(code, cfile)
    addFileToCompile(cfilenoext)
  elif not ExistsFile(toObjFile(cfilenoext)):
    # Consider: first compilation compiles ``system.nim`` and produces
    # ``system.c`` but then compilation fails due to an error. This means
    # that ``system.o`` is missing, so we need to call the C compiler for it:
    addFileToCompile(cfilenoext)
  addFileToLink(cfilenoext)

proc myClose(b: PPassContext, n: PNode): PNode = 
  result = n
  if b == nil or passes.skipCodegen(n): return 
  var m = BModule(b)
  if n != nil: 
    m.initProc.options = gOptions
    genStmts(m.initProc, n)
  # cached modules need to registered too: 
  registerModuleToMain(m.module)
  
  if optDeadCodeElim notin gGlobalOptions and
      sfDeadCodeElim notin m.module.flags: 
    finishModule(m)
  if sfMainModule in m.module.flags: 
    var disp = generateMethodDispatchers()
    for i in 0..sonsLen(disp)-1: genProcAux(m, disp.sons[i].sym)
    genMainProc(m) 
    # we need to process the transitive closure because recursive module
    # deps are allowed (and the system module is processed in the wrong
    # order anyway)
    while gForwardedProcsCounter > 0: 
      for i in countup(0, high(gPendingModules)): 
        finishModule(gPendingModules[i])
    for i in countup(0, high(gPendingModules)): 
      writeModule(gPendingModules[i], pending=true)
    setlen(gPendingModules, 0)
  if optDeadCodeElim notin gGlobalOptions and
      sfDeadCodeElim notin m.module.flags:
    writeModule(m, pending=false)
  if sfMainModule in m.module.flags: writeMapping(gMapping)
      
proc cgenPass(): TPass = 
  initPass(result)
  result.open = myOpen
  result.openCached = myOpenCached
  result.process = myProcess
  result.close = myClose