2 files changed, 8 insertions, 5 deletions
diff --git a/lib/system/alloc.nim b/lib/system/alloc.nim
index a7c504afc..6fd9efebd 100755
--- a/lib/system/alloc.nim
+++ b/lib/system/alloc.nim
@@ -478,6 +478,7 @@ proc getSmallChunk(a: var TMemRegion): PSmallChunk =
   result = cast[PSmallChunk](res)
 
 # -----------------------------------------------------------------------------
+proc isAllocatedPtr(a: TMemRegion, p: pointer): bool
 
 proc rawAlloc(a: var TMemRegion, requestedSize: int): pointer =
   sysAssert(roundup(65, 8) == 72, "rawAlloc 1")
@@ -537,7 +538,8 @@ proc rawAlloc0(a: var TMemRegion, requestedSize: int): pointer =
   result = rawAlloc(a, requestedSize)
   zeroMem(result, requestedSize)
 
-proc rawDealloc(a: var TMemRegion, p: pointer) = 
+proc rawDealloc(a: var TMemRegion, p: pointer) =
+  sysAssert(isAllocatedPtr(a, p), "rawDealloc: no allocated pointer!")
   var c = pageAddr(p)
   if isSmallChunk(c):
     # `p` is within a small chunk:
diff --git a/lib/system/gc.nim b/lib/system/gc.nim
index 2f6b5d395..2ac61fca0 100755
--- a/lib/system/gc.nim
+++ b/lib/system/gc.nim
@@ -222,11 +222,8 @@ proc rtlAddZCT(c: PCell) {.rtl, inl.} =
     ReleaseSys(HeapLock)
 
 proc decRef(c: PCell) {.inline.} =
-  when stressGC:
-    if c.refcount <% rcIncrement:
-      writeCell("broken cell", c)
+  sysAssert(isAllocatedPtr(gch.region, c), "decRef: interiorPtr")
   sysAssert(c.refcount >=% rcIncrement, "decRef")
-  #if c.refcount <% rcIncrement: quit("leck mich")
   if --c.refcount:
     rtlAddZCT(c)
   elif canBeCycleRoot(c):
@@ -235,6 +232,7 @@ proc decRef(c: PCell) {.inline.} =
     rtlAddCycleRoot(c) 
 
 proc incRef(c: PCell) {.inline.} = 
+  sysAssert(isAllocatedPtr(gch.region, c), "incRef: interiorPtr")
   ++c.refcount
   if canBeCycleRoot(c):
     rtlAddCycleRoot(c)
@@ -500,6 +498,7 @@ proc doOperation(p: pointer, op: TWalkOp) =
   sysAssert(c != nil, "doOperation: 1")
   case op # faster than function pointers because of easy prediction
   of waZctDecRef:
+    sysAssert(isAllocatedPtr(gch.region, c), "decRef: waZctDecRef")
     sysAssert(c.refcount >=% rcIncrement, "doOperation 2")
     c.refcount = c.refcount -% rcIncrement
     when logGC: writeCell("decref (from doOperation)", c)
@@ -727,8 +726,10 @@ proc CollectZCT(gch: var TGcHeap) =
   var L = addr(gch.zct.len)
   while L[] > 0:
     var c = gch.zct.d[0]
+    sysAssert(isAllocatedPtr(gch.region, c), "CollectZCT: isAllocatedPtr")
     # remove from ZCT:
     sysAssert((c.refcount and rcZct) == rcZct, "collectZCT")
+    
     c.refcount = c.refcount and not colorMask
     gch.zct.d[0] = gch.zct.d[L[] - 1]
     dec(L[])