revert to old GC; use --gc:v2 to activate the new GC

compiler/main.nim

@@ -427,14 +427,15 @@ proc resetMemory =
   # XXX: detect config reloading (implement as error/require restart)
   # XXX: options are appended (they will accumulate over time)
   # vis = visimpl
-  gcDebugging = true
-  echo "COLLECT 1"
-  GC_fullCollect()
-  echo "COLLECT 2"
-  GC_fullCollect()
-  echo "COLLECT 3"
-  GC_fullCollect()
-  echo GC_getStatistics()
+  when compileOption("gc", "v2"):
+    gcDebugging = true
+    echo "COLLECT 1"
+    GC_fullCollect()
+    echo "COLLECT 2"
+    GC_fullCollect()
+    echo "COLLECT 3"
+    GC_fullCollect()
+    echo GC_getStatistics()
 
 const
   SimiluateCaasMemReset = false

compiler/nimrod.nim

@@ -69,11 +69,12 @@ proc HandleCmdLine() =
             changeFileExt(gProjectFull, exeExt).prependCurDir)
           execExternalProgram(ex & ' ' & service.arguments)
 
-#GC_disableMarkAndSweep()
-
 when defined(GC_setMaxPause):
   GC_setMaxPause 2_000
-GC_disableMarkAndSweep()
+
+when compileOption("gc", "v2"):
+  # the new correct mark&sweet collector is too slow :-/
+  GC_disableMarkAndSweep()
 condsyms.InitDefines()
 HandleCmdLine()
 quit(options.gExitcode)

lib/system/mmdisp.nim

@@ -307,10 +307,10 @@ else:
   include "system/cellsets"
   when not leakDetector:
     sysAssert(sizeof(TCell) == sizeof(TFreeCell), "sizeof TFreeCell")
-  when true:
-    include "system/gc"
+  when compileOption("gc", "v2"):
+    include "system/gc2"
   else:
-    include "system/oldgc"
+    include "system/gc"
   
 {.pop.}
 

lib/system/sysstr.nim

@@ -203,16 +203,22 @@ proc setLengthSeq(seq: PGenericSeq, elemSize, newLen: int): PGenericSeq {.
   elif newLen < result.len:
     # we need to decref here, otherwise the GC leaks!
     when not defined(boehmGC) and not defined(nogc):
-      for i in newLen..result.len-1:
-        let len0 = gch.tempStack.len
-        forAllChildrenAux(cast[pointer](cast[TAddress](result) +%
-                          GenericSeqSize +% (i*%elemSize)),
-                          extGetCellType(result).base, waPush)
-        let len1 = gch.tempStack.len
-        for i in len0 .. <len1:
-          doDecRef(gch.tempStack.d[i], LocalHeap, MaybeCyclic)
-        gch.tempStack.len = len0
-                          
+      when compileOption("gc", "v2"):
+        for i in newLen..result.len-1:
+          let len0 = gch.tempStack.len
+          forAllChildrenAux(cast[pointer](cast[TAddress](result) +%
+                            GenericSeqSize +% (i*%elemSize)),
+                            extGetCellType(result).base, waPush)
+          let len1 = gch.tempStack.len
+          for i in len0 .. <len1:
+            doDecRef(gch.tempStack.d[i], LocalHeap, MaybeCyclic)
+          gch.tempStack.len = len0
+      else:
+        for i in newLen..result.len-1:
+          forAllChildrenAux(cast[pointer](cast[TAddress](result) +%
+                            GenericSeqSize +% (i*%elemSize)),
+                            extGetCellType(result).base, waZctDecRef)
+      
     # XXX: zeroing out the memory can still result in crashes if a wiped-out
     # cell is aliased by another pointer (ie proc paramter or a let variable).
     # This is a tought problem, because even if we don't zeroMem here, in the