func (cm *Merger) SetModeAndGranularity(mdf string, cmode coverage.CounterMode, cgran coverage.CounterGranularity) error {
	if cm.cmode == coverage.CtrModeInvalid {
		// Set merger mode based on what we're seeing here.
		cm.cmode = cmode
		cm.cgran = cgran
	} else {
		// Granularity clashes are always errors.
		if cm.cgran != cgran {

	}
}

func TestBasic(t *testing.T) {
	scenarios := []struct {
		cmode         coverage.CounterMode
		cgran         coverage.CounterGranularity
		src, dst, res []uint32
		iters         int
		merr          bool
		overflow      bool
	}{
		{
			cmode:    coverage.CtrModeSet,
			cgran:    coverage.CtrGranularityPerBlock,
			src:      []uint32{1, 0, 1},
			dst:      []uint32{1, 1, 0},

// hard-coded ID is needed), and 'cmode'/'cgran' are the coverage
// counter mode and granularity requested by the user. Return value is
// the ID for the package for use by the package code itself,
// or 0 for impossible errors.
func AddMeta(p unsafe.Pointer, dlen uint32, hash [16]byte, pkgpath string, pkgid int, cmode uint8, cgran uint8) uint32 {
	slot := len(Meta.List)
	Meta.List = append(Meta.List, CovMetaBlob{

// The compiler emits calls to runtime.addCovMeta
// but this code has moved to rtcov.AddMeta.
func addCovMeta(p unsafe.Pointer, dlen uint32, hash [16]byte, pkgpath string, pkgid int, cmode uint8, cgran uint8) uint32 {
	id := rtcov.AddMeta(p, dlen, hash, pkgpath, pkgid, cmode, cgran)
	if id == 0 {
		throw("runtime.addCovMeta: coverage package map collision")
	}
	return id

		if granClash(ecg) {
			return nil, fmt.Errorf("coverage counter granularity clash: package %s uses gran=%d, but package %s uses gran=%s\n", ml[0].PkgPath, cgran, entry.PkgPath, ecg)
		}
	}

	// Hash mode and granularity as well.
	h.Write([]byte(cmode.String()))
	h.Write([]byte(cgran.String()))

	// Compute final digest.
	fh := h.Sum(nil)
	copy(finalHash[:], fh)
	finalHashComputed = true

	// Materialize expression for length.
	lenx := ir.NewInt(base.Pos, int64(mdlen)) // untyped

	// Generate a call to runtime.addCovMeta, e.g.
	//
	//   pkgIdVar = runtime.addCovMeta(&sym, len, hash, pkgpath, pkid, cmode, cgran)
	//
	fn := typecheck.LookupRuntime("addCovMeta")
	pkid := coverage.HardCodedPkgID(base.Ctxt.Pkgpath)
	pkIdNode := ir.NewInt(base.Pos, int64(pkid))
	cmodeNode := ir.NewInt(base.Pos, int64(cnames.CounterMode))

	}
	if !finalHashComputed {
		return fmt.Errorf("error: no meta-data available (binary not built with -cover?)")
	}
	ml := rtcov.Meta.List
	return writeMetaData(w, ml, cmode, cgran, finalHash)
}

// WriteCountersDir implements [runtime/coverage.WriteCountersDir].
func WriteCountersDir(dir string) error {
	if cmode != coverage.CtrModeAtomic {

	if err := json.Unmarshal(data, &pkgconfig); err != nil {
		return fmt.Errorf("error reading pkgconfig file %q: %v", path, err)
	}
	switch pkgconfig.Granularity {
	case "perblock":
		cgran = coverage.CtrGranularityPerBlock
	case "perfunc":
		cgran = coverage.CtrGranularityPerFunc
	default:
		return fmt.Errorf(`%s: pkgconfig requires perblock/perfunc value`, path)
	}
	return nil
}

func libfuzzerHookStrCmp(string, string, uint)
func libfuzzerHookEqualFold(string, string, uint)

func addCovMeta(p unsafe.Pointer, len uint32, hash [16]byte, pkpath string, pkgId int, cmode uint8, cgran uint8) uint32

// architecture variants
var x86HasPOPCNT bool
var x86HasSSE41 bool
var x86HasFMA bool
var armHasVFPv4 bool
var arm64HasATOMICS bool

		md := mfr.CounterMode()
		wmd := coverage.CtrModeAtomic
		if md != wmd {
			t.Fatalf("k=%d wanted mode %d got %d", k, wmd, md)
		}
		gran := mfr.CounterGranularity()
		wgran := coverage.CtrGranularityPerBlock
		if gran != wgran {
			t.Fatalf("k=%d wanted gran %d got %d", k, wgran, gran)
		}

		payload := []byte{}
		for pi := 0; pi < int(np); pi++ {
			var pd *decodemeta.CoverageMetaDataDecoder
			var err error