code cleanup

lib/system/cyclicrefs_v2.nim

@@ -1,207 +0,0 @@
-#
-#
-#            Nim's Runtime Library
-#        (c) Copyright 2019 Andreas Rumpf
-#
-#    See the file "copying.txt", included in this
-#    distribution, for details about the copyright.
-#
-
-# Cycle collector based on Lins' Jump Stack and other ideas,
-# see for example:
-# https://pdfs.semanticscholar.org/f2b2/0d168acf38ff86305809a55ef2c5d6ebc787.pdf
-# Further refinement in 2008 by the notion of "critical links", see
-# "Cyclic reference counting" by Rafael Dueire Lins
-# R.D. Lins / Information Processing Letters 109 (2008) 71–78
-
-type PT = ptr pointer
-include cellseqs_v2
-
-const
-  colGreen = 0b000
-  colYellow = 0b001
-  colRed = 0b010
-  jumpStackFlag = 0b100  # stored in jumpstack
-  rcShift = 3      # shift by rcShift to get the reference counter
-  colorMask = 0b011
-
-type
-  TraceProc = proc (p, env: pointer) {.nimcall, benign.}
-  DisposeProc = proc (p: pointer) {.nimcall, benign.}
-
-template color(c): untyped = c.rc and colorMask
-template setColor(c, col) =
-  when col == colGreen:
-    c.rc = c.rc and not colorMask
-  else:
-    c.rc = c.rc and not colorMask or col
-
-proc nimIncRefCyclic(p: pointer) {.compilerRtl, inl.} =
-  let h = head(p)
-  inc h.rc, rcIncrement
-  h.setColor colYellow # mark as potential cycle!
-
-proc markCyclic*[T](x: ref T) {.inline.} =
-  ## Mark the underlying object as a candidate for cycle collections.
-  ## Experimental API. Do not use!
-  let h = head(cast[pointer](x))
-  h.setColor colYellow
-
-type
-  GcEnv = object
-    traceStack: CellSeq
-    jumpStack: CellSeq
-
-proc trace(s: Cell; desc: PNimType; j: var GcEnv) {.inline.} =
-  if desc.traceImpl != nil:
-    var p = s +! sizeof(RefHeader)
-    cast[TraceProc](desc.traceImpl)(p, addr(j))
-
-proc free(s: Cell; desc: PNimType) {.inline.} =
-  when traceCollector:
-    cprintf("[From ] %p rc %ld color %ld in jumpstack %ld\n", s, s.rc shr rcShift,
-            s.color, s.rc and jumpStackFlag)
-  let p = s +! sizeof(RefHeader)
-  if desc.disposeImpl != nil:
-    cast[DisposeProc](desc.disposeImpl)(p)
-  nimRawDispose(p)
-
-proc collect(s: Cell; desc: PNimType; j: var GcEnv) =
-  #[ Algorithm from the paper:
-
-    Collect(S) =
-      If (Color(S) == red) then
-        RC(S) = 1;
-        Color(S) = green;
-        for T in Sons(S) do
-          Remove(<S, T>);
-          if (Color(T) == red) then Collect(T);
-      free_list = S;
-
-  (Whatever that really means...)
-  ]#
-  if s.color == colRed:
-    s.setColor colGreen
-    trace(s, desc, j)
-    while j.traceStack.len > 0:
-      let (p, desc) = j.traceStack.pop()
-      let t = head(p[])
-      #Remove(<S, T>):
-      p[] = nil
-      if t.color == colRed:
-        t.setColor colGreen
-        trace(t, desc, j)
-        free(t, desc)
-    free(s, desc)
-    #cprintf("[Cycle free] %p %ld\n", s, s.rc shr rcShift)
-
-proc markRed(s: Cell; desc: PNimType; j: var GcEnv) =
-  if s.color != colRed:
-    s.setColor colRed
-    trace(s, desc, j)
-    while j.traceStack.len > 0:
-      let (p, desc) = j.traceStack.pop()
-      let t = head(p[])
-      when traceCollector:
-        cprintf("[Cycle dec] %p %ld color %ld in jumpstack %ld\n", t, t.rc shr rcShift, t.color, t.rc and jumpStackFlag)
-      dec t.rc, rcIncrement
-      if (t.rc and not rcMask) >= 0 and (t.rc and jumpStackFlag) == 0:
-        t.rc = t.rc or jumpStackFlag
-        when traceCollector:
-          cprintf("[Now in jumpstack] %p %ld color %ld in jumpstack %ld\n", t, t.rc shr rcShift, t.color, t.rc and jumpStackFlag)
-        j.jumpStack.add(p, desc)
-      if t.color != colRed:
-        t.setColor colRed
-        trace(t, desc, j)
-
-proc scanGreen(s: Cell; desc: PNimType; j: var GcEnv) =
-  s.setColor colGreen
-  trace(s, desc, j)
-  while j.traceStack.len > 0:
-    let (p, desc) = j.traceStack.pop()
-    let t = head(p[])
-    if t.color != colGreen:
-      t.setColor colGreen
-      trace(t, desc, j)
-    inc t.rc, rcIncrement
-    when traceCollector:
-      cprintf("[Cycle inc] %p %ld color %ld\n", t, t.rc shr rcShift, t.color)
-
-proc nimTraceRef(q: pointer; desc: PNimType; env: pointer) {.compilerRtl.} =
-  let p = cast[ptr pointer](q)
-  if p[] != nil:
-    var j = cast[ptr GcEnv](env)
-    j.traceStack.add(p, desc)
-
-proc nimTraceRefDyn(q: pointer; env: pointer) {.compilerRtl.} =
-  let p = cast[ptr pointer](q)
-  if p[] != nil:
-    var j = cast[ptr GcEnv](env)
-    j.traceStack.add(p, cast[ptr PNimType](p[])[])
-
-proc scan(s: Cell; desc: PNimType; j: var GcEnv) =
-  when traceCollector:
-    cprintf("[doScanGreen] %p %ld\n", s, s.rc shr rcShift)
-  # even after trial deletion, `s` is still alive, so undo
-  # the decrefs by calling `scanGreen`:
-  if (s.rc and not rcMask) >= 0:
-    scanGreen(s, desc, j)
-    s.setColor colYellow
-  else:
-    # first we have to repair all the nodes we have seen
-    # that are still alive; we also need to mark what they
-    # refer to as alive:
-    while j.jumpStack.len > 0:
-      let (p, desc) = j.jumpStack.pop
-      let t = head(p[])
-      # not in jump stack anymore!
-      t.rc = t.rc and not jumpStackFlag
-      if t.color == colRed and (t.rc and not rcMask) >= 0:
-        scanGreen(t, desc, j)
-        t.setColor colYellow
-        when traceCollector:
-          cprintf("[jump stack] %p %ld\n", t, t.rc shr rcShift)
-    # we have proven that `s` and its subgraph are dead, so we can
-    # collect these nodes:
-    collect(s, desc, j)
-
-proc traceCycle(s: Cell; desc: PNimType) {.noinline.} =
-  when traceCollector:
-    cprintf("[traceCycle] %p %ld\n", s, s.rc shr rcShift)
-  var j: GcEnv
-  init j.jumpStack
-  init j.traceStack
-  markRed(s, desc, j)
-  scan(s, desc, j)
-  while j.jumpStack.len > 0:
-    let (p, desc) = j.jumpStack.pop
-    let t = head(p[])
-    # not in jump stack anymore!
-    t.rc = t.rc and not jumpStackFlag
-  deinit j.jumpStack
-  deinit j.traceStack
-
-proc nimDecRefIsLastCyclicDyn(p: pointer): bool {.compilerRtl, inl.} =
-  if p != nil:
-    var cell = head(p)
-    if (cell.rc and not rcMask) == 0:
-      result = true
-      #cprintf("[DESTROY] %p\n", p)
-    else:
-      dec cell.rc, rcIncrement
-      if cell.color == colYellow:
-        let desc = cast[ptr PNimType](p)[]
-        traceCycle(cell, desc)
-      # According to Lins it's correct to do nothing else here.
-      #cprintf("[DeCREF] %p\n", p)
-
-proc nimDecRefIsLastCyclicStatic(p: pointer; desc: PNimType): bool {.compilerRtl, inl.} =
-  if p != nil:
-    var cell = head(p)
-    if (cell.rc and not rcMask) == 0:
-      result = true
-      #cprintf("[DESTROY] %p %s\n", p, desc.name)
-    else:
-      dec cell.rc, rcIncrement
-      if cell.color == colYellow: traceCycle(cell, desc)
-      #cprintf("[DeCREF] %p %s %ld\n", p, desc.name, cell.rc)

lib/system/refs_v2.nim

@@ -180,9 +180,8 @@ when defined(gcOrc):
   when defined(nimThinout):
     include cyclebreaker
   else:
-    include cyclicrefs_bacon
+    include orc
     #include cyclecollector
-    #include cyclicrefs_v2
 
 proc nimDecRefIsLast(p: pointer): bool {.compilerRtl, inl.} =
   if p != nil: