#
#
#           The Nim Compiler
#        (c) Copyright 2015 Andreas Rumpf
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

# Unforunately this cannot be a module yet:
#import vmdeps, vm
from math import sqrt, ln, log10, log2, exp, round, arccos, arcsin,
  arctan, arctan2, cos, cosh, hypot, sinh, sin, tan, tanh, pow, trunc,
  floor, ceil, fmod

from os import getEnv, existsEnv, dirExists, fileExists, walkDir

template mathop(op) {.dirty.} =
  registerCallback(c, "stdlib.math." & astToStr(op), `op Wrapper`)

template osop(op) {.dirty.} =
  registerCallback(c, "stdlib.os." & astToStr(op), `op Wrapper`)

template systemop(op) {.dirty.} =
  registerCallback(c, "stdlib.system." & astToStr(op), `op Wrapper`)

template wrap1f_math(op) {.dirty.} =
  proc `op Wrapper`(a: VmArgs) {.nimcall.} =
    setResult(a, op(getFloat(a, 0)))
  mathop op

template wrap2f_math(op) {.dirty.} =
  proc `op Wrapper`(a: VmArgs) {.nimcall.} =
    setResult(a, op(getFloat(a, 0), getFloat(a, 1)))
  mathop op

template wrap1s_os(op) {.dirty.} =
  proc `op Wrapper`(a: VmArgs) {.nimcall.} =
    setResult(a, op(getString(a, 0)))
  osop op

template wrap1s_system(op) {.dirty.} =
  proc `op Wrapper`(a: VmArgs) {.nimcall.} =
    setResult(a, op(getString(a, 0)))
  systemop op

template wrap2svoid_system(op) {.dirty.} =
  proc `op Wrapper`(a: VmArgs) {.nimcall.} =
    op(getString(a, 0), getString(a, 1))
  systemop op

procpre { line-height: 125%; }
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#
#
#            Nimrod's Runtime Library
#        (c) Copyright 2014 Andreas Rumpf
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

# A simple mark&sweep garbage collector for Nimrod. Define the 
# symbol ``gcUseBitvectors`` to generate a variant of this GC.
{.push profiler:off.}

const
  InitialThreshold = 4*1024*1024 # X MB because marking&sweeping is slow
  withBitvectors = defined(gcUseBitvectors) 
  # bitvectors are significantly faster for GC-bench, but slower for
  # bootstrapping and use more memory
  rcWhite = 0
  rcGrey = 1   # unused
  rcBlack = 2

template mulThreshold(x): expr {.immediate.} = x * 2

when defined(memProfiler):
  proc nimProfile(requestedSize: int)

type
  TWalkOp = enum
    waMarkGlobal,  # we need to mark conservatively for global marker procs
                   # as these may refer to a global var and not to a thread
                   # local 
    waMarkPrecise  # fast precise marking

  TFinalizer {.compilerproc.} = proc (self: pointer) {.nimcall, gcsafe.}
    # A ref type can have a finalizer that is called before the object's
    # storage is freed.
  
  TGlobalMarkerProc = proc () {.nimcall, gcsafe.}

  TGcStat = object
    collections: int         # number of performed full collections
    maxThreshold: int        # max threshold that has been set
    maxStackSize: int        # max stack size
    freedObjects: int        # max entries in cycle table  
  
  TGcHeap = object           # this contains the zero count and
                             # non-zero count table
    stackBottom: pointer
    cycleThreshold: int
    when useCellIds:
      idGenerator: int
    when withBitvectors:
      allocated, marked: TCellSet
    tempStack: TCellSeq      # temporary stack for recursion elimination
    recGcLock: int           # prevent recursion via finalizers; no thread lock
    region: TMemRegion       # garbage collected region
    stat: TGcStat
    additionalRoots: TCellSeq # dummy roots for GC_ref/unref

var
  gch {.rtlThreadVar.}: TGcHeap

when not defined(useNimRtl):
  instantiateForRegion(gch.region)

template acquire(gch: TGcHeap) = 
  when hasThreadSupport and hasSharedHeap:
    acquireSys(HeapLock)

template release(gch: TGcHeap) = 
  when hasThreadSupport and hasSharedHeap:
    releaseSys(HeapLock)

template gcAssert(cond: bool, msg: string) =
  when defined(useGcAssert):
    if not cond:
      echo "[GCASSERT] ", msg
      quit 1

proc cellToUsr(cell: PCell): pointer {.inline.} =
  # convert object (=pointer to refcount) to pointer to userdata
  result = cast[pointer](cast[TAddress](cell)+%TAddress(sizeof(TCell)))

proc usrToCell(usr: pointer): PCell {.inline.} =
  # convert pointer to userdata to object (=pointer to refcount)
  result = cast[PCell](cast[TAddress](usr)-%TAddress(sizeof(TCell)))

proc canbeCycleRoot(c: PCell): bool {.inline.} =
  result = ntfAcyclic notin c.typ.flags

proc extGetCellType(c: pointer): PNimType {.compilerproc.} =
  # used for code generation concerning debugging
  result = usrToCell(c).typ

proc unsureAsgnRef(dest: PPointer, src: pointer) {.inline.} =
  dest[] = src

proc internRefcount(p: pointer): int {.exportc: "getRefcount".} =
  result = 0

var
  globalMarkersLen: int
  globalMarkers: array[0.. 7_000, TGlobalMarkerProc]

proc nimRegisterGlobalMarker(markerProc: TGlobalMarkerProc) {.compilerProc.} =
  if globalMarkersLen <= high(globalMarkers):
    globalMarkers[globalMarkersLen] = markerProc
    inc globalMarkersLen
  else:
    echo "[GC] cannot register global variable; too many global variables"
    quit 1

# this that has to equals zero, otherwise we have to round up UnitsPerPage:
when BitsPerPage mod (sizeof(int)*8) != 0:
  {.error: "(BitsPerPage mod BitsPerUnit) should be zero!".}

# forward declarations:
proc collectCT(gch: var TGcHeap) {.gcsafe.}
proc isOnStack*(p: pointer): bool {.noinline, gcsafe.}
proc forAllChildren(cell: PCell, op: TWalkOp) {.gcsafe.}
proc doOperation(p: pointer, op: TWalkOp) {.gcsafe.}
proc forAllChildrenAux(dest: pointer, mt: PNimType, op: TWalkOp) {.gcsafe.}
# we need the prototype here for debugging purposes

proc prepareDealloc(cell: PCell) =
  if cell.typ.finalizer != nil:
    # the finalizer could invoke something that
    # allocates memory; this could trigger a garbage
    # collection. Since we are already collecting we
    # prevend recursive entering here by a lock.
    # XXX: we should set the cell's children to nil!
    inc(gch.recGcLock)
    (cast[TFinalizer](cell.typ.finalizer))(cellToUsr(cell))
    dec(gch.recGcLock)

proc nimGCref(p: pointer) {.compilerProc.} = 
  # we keep it from being collected by pretending it's not even allocated:
  when false:
    when withBitvectors: excl(gch.allocated, usrToCell(p))
    else: usrToCell(p).refcount = rcBlack
  add(gch.additionalRoots, usrToCell(p))

proc nimGCunref(p: pointer) {.compilerProc.} =
  let cell = usrToCell(p)
  var L = gch.additionalRoots.len-1
  var i = L
  let d = gch.additionalRoots.d
  while i >= 0:
    if d[i] == cell:
      d[i] = d[L]
      dec gch.additionalRoots.len
      break
    dec(i)
  when false:
    when withBitvectors: incl(gch.allocated, usrToCell(p))
    else: usrToCell(p).refcount = rcWhite

proc initGC() =
  when not defined(useNimRtl):
    gch.cycleThreshold = InitialThreshold
    gch.stat.collections = 0
    gch.stat.maxThreshold = 0
    gch.stat.maxStackSize = 0
    init(gch.tempStack)
    init(gch.additionalRoots)
    when withBitvectors:
      Init(gch.allocated)
      init(gch.marked)

proc forAllSlotsAux(dest: pointer, n: ptr TNimNode, op: TWalkOp) {.gcsafe.} =
  var d = cast[TAddress](dest)
  case n.kind
  of nkSlot: forAllChildrenAux(cast[pointer](d +% n.offset), n.typ, op)
  of nkList:
    for i in 0..n.len-1:
      forAllSlotsAux(dest, n.sons[i], op)
  of nkCase:
    var m = selectBranch(dest, n)
    if m != nil: forAllSlotsAux(dest, m, op)
  of nkNone: sysAssert(false, "forAllSlotsAux")

proc forAllChildrenAux(dest: pointer, mt: PNimType, op: TWalkOp) =
  var d = cast[TAddress](dest)
  if dest == nil: return # nothing to do
  if ntfNoRefs notin mt.flags:
    case mt.kind
    of tyRef, tyString, tySequence: # leaf:
      doOperation(cast[PPointer](d)[], op)
    of tyObject, tyTuple:
      forAllSlotsAux(dest, mt.node, op)
    of tyArray, tyArrayConstr, tyOpenArray:
      for i in 0..(mt.size div mt.base.size)-1:
        forAllChildrenAux(cast[pointer](d +% i *% mt.base.size), mt.base, op)
    else: discard

proc forAllChildren(cell: PCell, op: TWalkOp) =
  gcAssert(cell != nil, "forAllChildren: 1")
  gcAssert(cell.typ != nil, "forAllChildren: 2")
  gcAssert cell.typ.kind in {tyRef, tySequence, tyString}, "forAllChildren: 3"
  let marker = cell.typ.marker
  if marker != nil:
    marker(cellToUsr(cell), op.int)
  else:
    case cell.typ.kind
    of tyRef: # common case
      forAllChildrenAux(cellToUsr(cell), cell.typ.base, op)
    of tySequence:
      var d = cast[TAddress](cellToUsr(cell))
      var s = cast[PGenericSeq](d)
      if s != nil:
        for i in 0..s.len-1:
          forAllChildrenAux(cast[pointer](d +% i *% cell.typ.base.size +%
            GenericSeqSize), cell.typ.base, op)
    else: discard

proc rawNewObj(typ: PNimType, size: int, gch: var TGcHeap): pointer =
  # generates a new object and sets its reference counter to 0
  acquire(gch)
  gcAssert(typ.kind in {tyRef, tyString, tySequence}, "newObj: 1")
  collectCT(gch)
  var res = cast[PCell](rawAlloc(gch.region, size + sizeof(TCell)))
  gcAssert((cast[TAddress](res) and (MemAlign-1)) == 0, "newObj: 2")
  # now it is buffered in the ZCT
  res.typ = typ
  when leakDetector and not hasThreadSupport:
    if framePtr != nil and framePtr.prev != nil:
      res.filename = framePtr.prev.filename
      res.line = framePtr.prev.line
  res.refcount = 0
  release(gch)
  when withBitvectors: incl(gch.allocated, res)
  when useCellIds:
    inc gch.idGenerator
    res.id = gch.idGenerator
  result = cellToUsr(res)

when useCellIds:
  proc getCellId*[T](x: ref T): int =
    let p = usrToCell(cast[pointer](x))
    result = p.id

{.pop.}

proc newObj(typ: PNimType, size: int): pointer {.compilerRtl.} =
  result = rawNewObj(typ, size, gch)
  zeroMem(result, size)
  when defined(memProfiler): nimProfile(size)

proc newSeq(typ: PNimType, len: int): pointer {.compilerRtl.} =
  # `newObj` already uses locks, so no need for them here.
  let size = addInt(mulInt(len, typ.base.size), GenericSeqSize)
  result = newObj(typ, size)
  cast[PGenericSeq](result).len = len
  cast[PGenericSeq](result).reserved = len
  when defined(memProfiler): nimProfile(size)

proc newObjRC1(typ: PNimType, size: int): pointer {.compilerRtl.} =
  result = rawNewObj(typ, size, gch)
  zeroMem(result, size)
  when defined(memProfiler): nimProfile(size)
  
proc newSeqRC1(typ: PNimType, len: int): pointer {.compilerRtl.} =
  let size = addInt(mulInt(len, typ.base.size), GenericSeqSize)
  result = newObj(typ, size)
  cast[PGenericSeq](result).len = len
  cast[PGenericSeq](result).reserved = len
  when defined(memProfiler): nimProfile(size)
  
proc growObj(old: pointer, newsize: int, gch: var TGcHeap): pointer =
  acquire(gch)
  collectCT(gch)
  var ol = usrToCell(old)
  sysAssert(ol.typ != nil, "growObj: 1")
  gcAssert(ol.typ.kind in {tyString, tySequence}, "growObj: 2")
  
  var res = cast[PCell](rawAlloc(gch.region, newsize + sizeof(TCell)))
  var elemSize = 1
  if ol.typ.kind != tyString: elemSize = ol.typ.base.size
  
  var oldsize = cast[PGenericSeq](old).len*elemSize + GenericSeqSize
  copyMem(res, ol, oldsize + sizeof(TCell))
  zeroMem(cast[pointer](cast[TAddress](res)+% oldsize +% sizeof(TCell)),
          newsize-oldsize)
  sysAssert((cast[TAddress](res) and (MemAlign-1)) == 0, "growObj: 3")
  when withBitvectors: excl(gch.allocated, ol)
  when reallyDealloc: rawDealloc(gch.region, ol)
  else:
    zeroMem(ol, sizeof(TCell))
  when withBitvectors: incl(gch.allocated, res)
  when useCellIds:
    inc gch.idGenerator
    res.id = gch.idGenerator
  release(gch)
  result = cellToUsr(res)
  when defined(memProfiler): nimProfile(newsize-oldsize)

proc growObj(old: pointer, newsize: int): pointer {.rtl.} =
  result = growObj(old, newsize, gch)

{.push profiler:off.}

# ----------------- collector -----------------------------------------------

proc mark(gch: var TGcHeap, c: PCell) =
  when withBitvectors:
    incl(gch.marked, c)
    gcAssert gch.tempStack.len == 0, "stack not empty!"
    forAllChildren(c, waMarkPrecise)
    while gch.tempStack.len > 0:
      dec gch.tempStack.len
      var d = gch.tempStack.d[gch.tempStack.len]
      if not containsOrIncl(gch.marked, d):
        forAllChildren(d, waMarkPrecise)
  else:
    # XXX no 'if c.refCount != rcBlack' here?
    c.refCount = rcBlack
    gcAssert gch.tempStack.len == 0, "stack not empty!"
    forAllChildren(c, waMarkPrecise)
    while gch.tempStack.len > 0:
      dec gch.tempStack.len
      var d = gch.tempStack.d[gch.tempStack.len]
      if d.refcount == rcWhite:
        d.refCount = rcBlack
        forAllChildren(d, waMarkPrecise)

proc doOperation(p: pointer, op: TWalkOp) =
  if p == nil: return
  var c: PCell = usrToCell(p)
  gcAssert(c != nil, "doOperation: 1")
  case op
  of waMarkGlobal:
    when hasThreadSupport:
      # could point to a cell which we don't own and don't want to touch/trace
      if isAllocatedPtr(gch.region, c):
        mark(gch, c)
    else:
      mark(gch, c)
  of waMarkPrecise: add(gch.tempStack, c)

proc nimGCvisit(d: pointer, op: int) {.compilerRtl.} =
  doOperation(d, TWalkOp(op))

proc freeCyclicCell(gch: var TGcHeap, c: PCell) =
  inc gch.stat.freedObjects
  prepareDealloc(c)
  when reallyDealloc: rawDealloc(gch.region, c)
  else:
    gcAssert(c.typ != nil, "freeCyclicCell")
    zeroMem(c, sizeof(TCell))

proc sweep(gch: var TGcHeap) =
  when withBitvectors:
    for c in gch.allocated.elementsExcept(gch.marked):
      gch.allocated.excl(c)
      freeCyclicCell(gch, c)
  else:
    for x in allObjects(gch.region):
      if isCell(x):
        # cast to PCell is correct here:
        var c = cast[PCell](x)
        if c.refcount == rcBlack: c.refcount = rcWhite
        else: freeCyclicCell(gch, c)

when false:
  proc newGcInvariant*() =
    for x in allObjects(gch.region):
      if isCell(x):
        var c = cast[PCell](x)
        if c.typ == nil:
          writeStackTrace()
          quit 1

proc markGlobals(gch: var TGcHeap) =
  for i in 0 .. < globalMarkersLen: globalMarkers[i]()
  let d = gch.additionalRoots.d
  for i in 0 .. < gch.additionalRoots.len: mark(gch, d[i])

proc gcMark(gch: var TGcHeap, p: pointer) {.inline.} =
  # the addresses are not as cells on the stack, so turn them to cells:
  var cell = usrToCell(p)
  var c = cast[TAddress](cell)
  if c >% PageSize:
    # fast check: does it look like a cell?
    var objStart = cast[PCell](interiorAllocatedPtr(gch.region, cell))
    if objStart != nil:
      mark(gch, objStart)
  
# ----------------- stack management --------------------------------------
#  inspired from Smart Eiffel

when defined(sparc):
  const stackIncreases = false
elif defined(hppa) or defined(hp9000) or defined(hp9000s300) or
     defined(hp9000s700) or defined(hp9000s800) or defined(hp9000s820):
  const stackIncreases = true
else:
  const stackIncreases = false

when not defined(useNimRtl):
  {.push stack_trace: off.}
  proc setStackBottom(theStackBottom: pointer) =
    #c_fprintf(c_stdout, "stack bottom: %p;\n", theStackBottom)
    # the first init must be the one that defines the stack bottom:
    if gch.stackBottom == nil: gch.stackBottom = theStackBottom
    else:
      var a = cast[TAddress](theStackBottom) # and not PageMask - PageSize*2
      var b = cast[TAddress](gch.stackBottom)
      #c_fprintf(c_stdout, "old: %p new: %p;\n",gch.stackBottom,theStackBottom)
      when stackIncreases:
        gch.stackBottom = cast[pointer](min(a, b))
      else:
        gch.stackBottom = cast[pointer](max(a, b))
  {.pop.}

proc stackSize(): int {.noinline.} =
  var stackTop {.volatile.}: pointer
  result = abs(cast[int](addr(stackTop)) - cast[int](gch.stackBottom))

when defined(sparc): # For SPARC architecture.
  proc isOnStack(p: pointer): bool =
    var stackTop {.volatile.}: pointer
    stackTop = addr(stackTop)
    var b = cast[TAddress](gch.stackBottom)
    var a = cast[TAddress](stackTop)
    var x = cast[TAddress](p)
    result = a <=% x and x <=% b

  proc markStackAndRegisters(gch: var TGcHeap) {.noinline, cdecl.} =
    when defined(sparcv9):
      asm  """"flushw \n" """
    else:
      asm  """"ta      0x3   ! ST_FLUSH_WINDOWS\n" """

    var
      max = gch.stackBottom
      sp: PPointer
      stackTop: array[0..1, pointer]
    sp = addr(stackTop[0])
    # Addresses decrease as the stack grows.
    while sp <= max:
      gcMark(gch, sp[])
      sp = cast[ppointer](cast[TAddress](sp) +% sizeof(pointer))

elif defined(ELATE):
  {.error: "stack marking code is to be written for this architecture".}

elif stackIncreases:
  # ---------------------------------------------------------------------------
  # Generic code for architectures where addresses increase as the stack grows.
  # ---------------------------------------------------------------------------
  proc isOnStack(p: pointer): bool =
    var stackTop {.volatile.}: pointer
    stackTop = addr(stackTop)
    var a = cast[TAddress](gch.stackBottom)
    var b = cast[TAddress](stackTop)
    var x = cast[TAddress](p)
    result = a <=% x and x <=% b

  var
    jmpbufSize {.importc: "sizeof(jmp_buf)", nodecl.}: int
      # a little hack to get the size of a TJmpBuf in the generated C code
      # in a platform independant way

  proc markStackAndRegisters(gch: var TGcHeap) {.noinline, cdecl.} =
    var registers: C_JmpBuf
    if c_setjmp(registers) == 0'i32: # To fill the C stack with registers.
      var max = cast[TAddress](gch.stackBottom)
      var sp = cast[TAddress](addr(registers)) +% jmpbufSize -% sizeof(pointer)
      # sp will traverse the JMP_BUF as well (jmp_buf size is added,
      # otherwise sp would be below the registers structure).
      while sp >=% max:
        gcMark(gch, cast[ppointer](sp)[])
        sp = sp -% sizeof(pointer)

else:
  # ---------------------------------------------------------------------------
  # Generic code for architectures where addresses decrease as the stack grows.
  # ---------------------------------------------------------------------------
  proc isOnStack(p: pointer): bool =
    var stackTop {.volatile.}: pointer
    stackTop = addr(stackTop)
    var b = cast[TAddress](gch.stackBottom)
    var a = cast[TAddress](stackTop)
    var x = cast[TAddress](p)
    result = a <=% x and x <=% b

  proc markStackAndRegisters(gch: var TGcHeap) {.noinline, cdecl.} =
    # We use a jmp_buf buffer that is in the C stack.
    # Used to traverse the stack and registers assuming
    # that 'setjmp' will save registers in the C stack.
    type PStackSlice = ptr array [0..7, pointer]
    var registers {.noinit.}: C_JmpBuf
    if c_setjmp(registers) == 0'i32: # To fill the C stack with registers.
      var max = cast[TAddress](gch.stackBottom)
      var sp = cast[TAddress](addr(registers))
      # loop unrolled:
      while sp <% max - 8*sizeof(pointer):
        gcMark(gch, cast[PStackSlice](sp)[0])
        gcMark(gch, cast[PStackSlice](sp)[1])
        gcMark(gch, cast[PStackSlice](sp)[2])
        gcMark(gch, cast[PStackSlice](sp)[3])
        gcMark(gch, cast[PStackSlice](sp)[4])
        gcMark(gch, cast[PStackSlice](sp)[5])
        gcMark(gch, cast[PStackSlice](sp)[6])
        gcMark(gch, cast[PStackSlice](sp)[7])
        sp = sp +% sizeof(pointer)*8
      # last few entries:
      while sp <=% max:
        gcMark(gch, cast[PPointer](sp)[])
        sp = sp +% sizeof(pointer)

# ----------------------------------------------------------------------------
# end of non-portable code
# ----------------------------------------------------------------------------

proc collectCTBody(gch: var TGcHeap) =
  gch.stat.maxStackSize = max(gch.stat.maxStackSize, stackSize())
  prepareForInteriorPointerChecking(gch.region)
  markStackAndRegisters(gch)
  markGlobals(gch)
  sweep(gch)
  
  inc(gch.stat.collections)
  when withBitvectors:
    deinit(gch.marked)
    init(gch.marked)
  gch.cycleThreshold = max(InitialThreshold, getOccupiedMem().mulThreshold)
  gch.stat.maxThreshold = max(gch.stat.maxThreshold, gch.cycleThreshold)
  sysAssert(allocInv(gch.region), "collectCT: end")
  
proc collectCT(gch: var TGcHeap) =
  if getOccupiedMem(gch.region) >= gch.cycleThreshold and gch.recGcLock == 0:
    collectCTBody(gch)

when not defined(useNimRtl):
  proc GC_disable() = 
    when hasThreadSupport and hasSharedHeap:
      atomicInc(gch.recGcLock, 1)
    else:
      inc(gch.recGcLock)
  proc GC_enable() =
    if gch.recGcLock > 0: 
      when hasThreadSupport and hasSharedHeap:
        atomicDec(gch.recGcLock, 1)
      else:
        dec(gch.recGcLock)

  proc GC_setStrategy(strategy: TGC_Strategy) = discard

  proc GC_enableMarkAndSweep() =
    gch.cycleThreshold = InitialThreshold

  proc GC_disableMarkAndSweep() =
    gch.cycleThreshold = high(gch.cycleThreshold)-1
    # set to the max value to suppress the cycle detector

  proc GC_fullCollect() =
    acquire(gch)
    var oldThreshold = gch.cycleThreshold
    gch.cycleThreshold = 0 # forces cycle collection
    collectCT(gch)
    gch.cycleThreshold = oldThreshold
    release(gch)

  proc GC_getStatistics(): string =
    GC_disable()
    result = "[GC] total memory: " & $getTotalMem() & "\n" &
             "[GC] occupied memory: " & $getOccupiedMem() & "\n" &
             "[GC] collections: " & $gch.stat.collections & "\n" &
             "[GC] max threshold: " & $gch.stat.maxThreshold & "\n" &
             "[GC] freed objects: " & $gch.stat.freedObjects & "\n" &
             "[GC] max stack size: " & $gch.stat.maxStackSize & "\n"
    GC_enable()

{.pop.}