// RUN: %boogie -noinfer -typeEncoding:m -useArrayTheory "%s" > "%t"
// RUN: %diff "%s.expect" "%t"
type Tid;
const unique nil: Tid;

function {:inline} UNALLOC():int { 0 }
function {:inline} WHITE():int { 1 }
function {:inline} GRAY():int { 2 }
function {:inline} BLACK():int { 3 }
function {:inline} Unalloc(i:int) returns(bool) { i <= 0 }
function {:inline} White(i:int) returns(bool) { i == 1 }
function {:inline} Gray(i:int) returns(bool) { i == 2 }
function {:inline} Black(i:int) returns(bool) { i >= 3 }

procedure {:yields} {:layer 2} YieldColorOnlyGetsDarker()
ensures {:layer 2} Color >= old(Color);
{
  yield;
  assert {:layer 2} Color >= old(Color);
}

procedure {:yields} {:layer 2,3} WriteBarrier({:linear "tid"} tid:Tid)
ensures {:atomic} |{ A: assert tid != nil; goto B, C; 
                     B: assume White(Color); Color := GRAY(); return true; 
                     C: return true;}|;
{
  var colorLocal:int;
  yield;
  call colorLocal := GetColorNoLock();
  call YieldColorOnlyGetsDarker();
  if (White(colorLocal)) { call WriteBarrierSlow(tid); }
  yield;
}

procedure {:yields} {:layer 1,2} WriteBarrierSlow({:linear "tid"} tid:Tid)
ensures {:atomic} |{ A: assert tid != nil; goto B, C; 
                     B: assume White(Color); Color := GRAY(); return true; 
                     C: return true; }|;
{
       var colorLocal:int;
       yield;
       call AcquireLock(tid);
       call colorLocal := GetColorLocked(tid);
       if (White(colorLocal)) { call SetColorLocked(tid, GRAY()); } 
       call ReleaseLock(tid);
       yield;
}

procedure {:yields} {:layer 0,1} AcquireLock({:linear "tid"} tid: Tid);
  ensures {:right} |{ A: assert tid != nil; assume lock == nil; lock := tid; return true; }|;

procedure {:yields} {:layer 0,1} ReleaseLock({:linear "tid"} tid: Tid);
  ensures {:left} |{ A: assert tid != nil; assert lock == tid; lock := nil; return true; }|;

procedure {:yields} {:layer 0,1} SetColorLocked({:linear "tid"} tid:Tid, newCol:int); 
  ensures {:atomic} |{A: assert tid != nil; assert lock == tid; Color := newCol; return true;}|;

procedure {:yields} {:layer 0,1} GetColorLocked({:linear "tid"} tid:Tid) returns (col:int);
  ensures {:both} |{A: assert tid != nil; assert lock == tid; col := Color; return true;}|;

procedure {:yields} {:layer 0,2} GetColorNoLock() returns (col:int);
  ensures {:atomic} |{A: col := Color; return true;}|;



function {:builtin "MapConst"} MapConstBool(bool): [Tid]bool;
function {:builtin "MapOr"} MapOr([Tid]bool, [Tid]bool) : [Tid]bool;

var {:layer 0} Color:int;
var {:layer 0} lock:Tid;

function {:inline} {:linear "tid"} TidCollector(x: Tid) : [Tid]bool
{
  MapConstBool(false)[x := true]
}
function {:inline} {:linear "tid"} TidSetCollector(x: [Tid]bool) : [Tid]bool
{
  x
}