// from the result if we have one, since mallocgc will add it back in.
		if reqSize <= smallSizeMax-8 {
			return uintptr(class_to_size[size_to_class8[divRoundUp(reqSize, smallSizeDiv)]]) - (reqSize - size)
		}
		return uintptr(class_to_size[size_to_class128[divRoundUp(reqSize-smallSizeMax, largeSizeDiv)]]) - (reqSize - size)
	}
	// Large object. Align reqSize up to the next page. Check for overflow.
	reqSize += pageSize - 1

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package runtime

import "unsafe"

func sbrk(n uintptr) unsafe.Pointer {
	grow := divRoundUp(n, physPageSize)
	size := growMemory(int32(grow))
	if size < 0 {
		return nil
	}
	resetMemoryDataView()
	return unsafe.Pointer(uintptr(size) * physPageSize)
}

// Implemented in src/runtime/sys_wasm.s

}

// alignDown rounds n down to a multiple of a. a must be a power of 2.
//
//go:nosplit
func alignDown(n, a uintptr) uintptr {
	return n &^ (a - 1)
}

// divRoundUp returns ceil(n / a).
func divRoundUp(n, a uintptr) uintptr {
	// a is generally a power of two. This will get inlined and
	// the compiler will optimize the division.
	return (n + a - 1) / a
}

	bytep, mask := (*gcBits)(p).bitp(n * 2)
	byteVal := atomic.Load8(bytep)
	return pinState{bytep, byteVal, mask}
}

func (s *mspan) pinnerBitSize() uintptr {
	return divRoundUp(uintptr(s.nelems)*2, 8)
}

// newPinnerBits returns a pointer to 8 byte aligned bytes to be used for this
// span's pinner bits. newPinnerBits is used to mark objects that are pinned.

func materializeGCProg(ptrdata uintptr, prog *byte) *mspan {
	// Each word of ptrdata needs one bit in the bitmap.
	bitmapBytes := divRoundUp(ptrdata, 8*goarch.PtrSize)
	// Compute the number of pages needed for bitmapBytes.
	pages := divRoundUp(bitmapBytes, pageSize)
	s := mheap_.allocManual(pages, spanAllocPtrScalarBits)
	runGCProg(addb(prog, 4), (*byte)(unsafe.Pointer(s.startAddr)))
	return s
}

			if hasHeader {
				size += mallocHeaderSize
			}
			var sizeclass uint8
			if size <= smallSizeMax-8 {
				sizeclass = size_to_class8[divRoundUp(size, smallSizeDiv)]
			} else {
				sizeclass = size_to_class128[divRoundUp(size-smallSizeMax, largeSizeDiv)]
			}
			size = uintptr(class_to_size[sizeclass])
			spc := makeSpanClass(sizeclass, noscan)
			span = c.alloc[spc]

		obj := uintptr(s.freeindex)
		if (*s.gcmarkBits.bytep(obj / 8)&^*s.allocBits.bytep(obj / 8))>>(obj%8) != 0 {
			s.reportZombies()
		}
		// Check remaining bytes.
		for i := obj/8 + 1; i < divRoundUp(uintptr(s.nelems), 8); i++ {
			if *s.gcmarkBits.bytep(i)&^*s.allocBits.bytep(i) != 0 {
				s.reportZombies()
			}
		}
	}

	// Count the number of free objects in this span.

//
// The world must be stopped.
func gcMarkRootPrepare() {
	assertWorldStopped()

	// Compute how many data and BSS root blocks there are.
	nBlocks := func(bytes uintptr) int {
		return int(divRoundUp(bytes, rootBlockBytes))
	}

	work.nDataRoots = 0
	work.nBSSRoots = 0

	// Scan globals.
	for _, datap := range activeModules() {
		nDataRoots := nBlocks(datap.edata - datap.data)