}
		// Round up the type to the size of the type.
		size = (size + gctyp.Size_ - 1) / gctyp.Size_ * gctyp.Size_
		if interior+size > x+maxIterBytes {
			size = x + maxIterBytes - interior
		}
		doubleCheckHeapPointersInterior(x, interior, size, dataSize, gctyp, header, span)
	}
	return
}

func doubleCheckHeapPointers(x, dataSize uintptr, typ *_type, header **_type, span *mspan) {
	// Check that scanning the full object works.

	s.largeType.PtrBytes = uintptr(ptr) - base + typ.PtrBytes

	// Double-check that the bitmap was written out correctly.
	const doubleCheck = false
	if doubleCheck {
		doubleCheckHeapPointersInterior(uintptr(ptr), uintptr(ptr), typ.Size_, typ.Size_, typ, &s.largeType, s)
	}
}

type writeUserArenaHeapBits struct {
	offset uintptr // offset in span that the low bit of mask represents the pointer state of.