// and otherwise sets obj's checkmark. It returns true if obj was
// already checkmarked.
func setCheckmark(obj, base, off uintptr, mbits markBits) bool {
	if !mbits.isMarked() {
		printlock()
		print("runtime: checkmarks found unexpected unmarked object obj=", hex(obj), "\n")
		print("runtime: found obj at *(", hex(base), "+", hex(off), ")\n")

		// Dump the source (base) object

		addr := s.base() + i*s.elemsize
		print(hex(addr))
		alloc := i < uintptr(s.freeindex) || abits.isMarked()
		if alloc {
			print(" alloc")
		} else {
			print(" free ")
		}
		if mbits.isMarked() {
			print(" marked  ")
		} else {
			print(" unmarked")
		}
		zombie := mbits.isMarked() && !alloc
		if zombie {
			print(" zombie")
		}
		print("\n")
		if zombie {

			continue
		}

		// Find all allocated objects.
		abits := s.allocBitsForIndex(0)
		for i := uintptr(0); i < uintptr(s.nelems); i++ {
			if abits.index < uintptr(s.freeindex) || abits.isMarked() {
				x := s.base() + i*s.elemsize
				trace.HeapObjectExists(x, s.typePointersOfUnchecked(x).typ)
			}
			abits.advance()
		}
	}

	// Write out all the goroutine stacks.
	forEachGRace(func(gp *g) {

	cIgnorableCased               // 101 // lower case if mappings exist
	cXORCase                      // 11x // case is cLower | ((rune&1) ^ x)

	maxCaseMode = cUpper
)

func (c info) isCased() bool {
	return c&casedMask != 0
}

func (c info) isCaseIgnorable() bool {
	return c&ignorableMask == ignorableValue
}

func (c info) isNotCasedAndNotCaseIgnorable() bool {
	return c&fullCasedMask == 0
}

			"(*bmap).keys",
			"(*bmap).overflow",
			"(*waitq).enqueue",
			"funcInfo.entry",

			// GC-related ones
			"cgoInRange",
			"gclinkptr.ptr",
			"guintptr.ptr",
			"heapBitsSlice",
			"markBits.isMarked",
			"muintptr.ptr",
			"puintptr.ptr",
			"spanOf",
			"spanOfUnchecked",
			"typePointers.nextFast",
			"(*gcWork).putFast",
			"(*gcWork).tryGetFast",
			"(*guintptr).set",
			"(*markBits).advance",

		if obj == 0 {
			continue
		}
		// TODO: Consider making two passes where the first
		// just prefetches the mark bits.
		mbits := span.markBitsForIndex(objIndex)
		if mbits.isMarked() {
			continue
		}
		mbits.setMarked()

		// Mark span.
		arena, pageIdx, pageMask := pageIndexOf(span.base())
		if arena.pageMarks[pageIdx]&pageMask == 0 {

	return markBits{bytep, mask, objIndex}
}

func (s *mspan) markBitsForBase() markBits {
	return markBits{&s.gcmarkBits.x, uint8(1), 0}
}

// isMarked reports whether mark bit m is set.
func (m markBits) isMarked() bool {
	return *m.bytep&m.mask != 0
}

// setMarked sets the marked bit in the markbits, atomically.
func (m markBits) setMarked() {

			gcDumpObject("base", base, off)
			gcDumpObject("obj", obj, ^uintptr(0))
			getg().m.traceback = 2
			throw("marking free object")
		}

		// If marked we have nothing to do.
		if mbits.isMarked() {
			return
		}
		mbits.setMarked()

		// Mark span.
		arena, pageIdx, pageMask := pageIndexOf(span.base())
		if arena.pageMarks[pageIdx]&pageMask == 0 {