165   Segment *Tail;  variable
263     DCHECK_EQ(Tail, &SentinelSegment);  in InitHeadAndTail()
271     Tail = S;  in InitHeadAndTail()
272     DCHECK_EQ(Head, Tail);  in InitHeadAndTail()
273     DCHECK_EQ(Tail->Next, &SentinelSegment);  in InitHeadAndTail()
274     DCHECK_EQ(Tail->Prev, &SentinelSegment);  in InitHeadAndTail()
282     DCHECK_NE(Tail, &SentinelSegment);  in AppendNewSegment()
283     DCHECK_EQ(Tail->Next, &SentinelSegment);  in AppendNewSegment()
286     S->Prev = Tail;  in AppendNewSegment()
287     Tail->Next = S;  in AppendNewSegment()
288     Tail = S;  in AppendNewSegment()
290     DCHECK_EQ(Tail->Next, &SentinelSegment);  in AppendNewSegment()
298         Tail(&SentinelSegment),  in Array()
304                                   Tail(&SentinelSegment),  in Array()
313                                            Tail(O.Tail),  in Array()
318     O.Tail = &SentinelSegment;  in Array()
328     Tail = O.Tail;
329     O.Tail = &SentinelSegment;
353     DCHECK((Size == 0 && Head == &SentinelSegment && Head == Tail) ||  in AppendEmplace()
354            (Size != 0 && Head != &SentinelSegment && Tail != &SentinelSegment));  in AppendEmplace()
362     DCHECK_NE(Tail, &SentinelSegment);  in AppendEmplace()
369     DCHECK_NE(Tail, &SentinelSegment);  in AppendEmplace()
370     auto Base = &Tail->Data;  in AppendEmplace()
385     DCHECK((Size == 0 && Head == &SentinelSegment && Head == Tail) ||  in Append()
386            (Size != 0 && Head != &SentinelSegment && Tail != &SentinelSegment));  in Append()
394     DCHECK_NE(Tail, &SentinelSegment);  in Append()
401     DCHECK_NE(Tail, &SentinelSegment);  in Append()
402     auto Base = &Tail->Data;  in Append()
405               reinterpret_cast<unsigned char *>(Tail) + SegmentSize);  in Append()
435     DCHECK_NE(Tail, &SentinelSegment);  in back()
462     // We compute the number of segments we're going to return from the tail by  in trim()
507       // Here we place the current tail segment to the freelist. To do this  in trim()
515       DCHECK_NE(Tail, &SentinelSegment);  in trim()
516       DCHECK_EQ(Tail->Next, &SentinelSegment);  in trim()
523         //                  ^ Head                ^ Tail  in trim()
529         //                  ^ Head          ^ Tail  in trim()
531         // The first step for us is to hold a reference to the tail of Mainlist,  in trim()
537         // Then, we also hold a reference to the "pre-tail" element, which we  in trim()
553         //   Tail = sPT  in trim()
555         auto SPT = Tail->Prev;  in trim()
557         Tail->Prev = &SentinelSegment;  in trim()
558         Tail->Next = Freelist;  in trim()
559         Freelist = Tail;  in trim()
560         Tail = SPT;  in trim()
563         DCHECK_EQ(Tail->Next, &SentinelSegment);  in trim()
574         //                  ^ Head                ^ Tail  in trim()
581         //                  ^ Head          ^ Tail  in trim()
591         //   Tail = sPT  in trim()
595         auto SPT = Tail->Prev;  in trim()
596         auto ST = Tail;  in trim()
601         Tail = SPT;  in trim()
605         DCHECK_EQ(Tail->Next, &SentinelSegment);  in trim()
612     // main list is "empty", or both the head and tail pointing to the sentinel  in trim()
614     if (Tail == &SentinelSegment)  in trim()
615       Head = Tail;  in trim()
618         (Size == 0 && Head == &SentinelSegment && Tail == &SentinelSegment) ||  in trim()
619         (Size != 0 && Head != &SentinelSegment && Tail != &SentinelSegment));  in trim()
622         (Freelist == &SentinelSegment && Tail->Next == &SentinelSegment));  in trim()
630     return Iterator<T>(Tail, Size, Size);  in end()
636     return Iterator<const T>(Tail, Size, Size);  in cend()