)

// Experiments.
const (
	// AllocFree is the alloc-free events experiment.
	AllocFree event.Experiment = 1 + iota
)

// Experimental events.
const (
	_ event.Type = 127 + iota

	// Experimental events for AllocFree.

	// Experimental heap span events. Added in Go 1.23.
	EvSpan      // heap span exists [timestamp, id, npages, type/class]

	return w.dot
}

func (w *Writer) closeDot() {
	if w.dot != nil {
		w.dot.Close() // sets w.dot = nil
	}
}

type dotWriter struct {
	w     *Writer
	state int
}

const (
	wstateBegin     = iota // initial state; must be zero
	wstateBeginLine        // beginning of line
	wstateCR               // wrote \r (possibly at end of line)
	wstateData             // writing data in middle of line
)

// statuses.
type traceGoStatus uint8

const (
	traceGoBad traceGoStatus = iota
	traceGoRunnable
	traceGoRunning
	traceGoSyscall
	traceGoWaiting
)

// traceProcStatus is the status of a P.
//
// They mostly correspond to the various P statuses.
type traceProcStatus uint8

const (
	traceProcBad traceProcStatus = iota
	traceProcRunning
	traceProcIdle
	traceProcSyscall

type Prog struct {
	Inst   []Inst
	Start  int // index of start instruction
	NumCap int // number of InstCapture insts in re
}

// An InstOp is an instruction opcode.
type InstOp uint8

const (
	InstAlt InstOp = iota
	InstAltMatch
	InstCapture
	InstEmptyWidth
	InstMatch
	InstFail
	InstNop
	InstRune
	InstRune1
	InstRuneAny
	InstRuneAnyNotNL
)

var instOpNames = []string{
	"InstAlt",
	"InstAltMatch",

// cXORCase can result in large series of identical trie values. This, in turn,
// allows us to better compress the trie blocks.
const (
	cUncased          info = iota // 000
	cTitle                        // 001
	cLower                        // 010
	cUpper                        // 011
	cIgnorableUncased             // 100

	"math"
	"unsafe"
)

// ValueKind is a tag for a metric [Value] which indicates its type.
type ValueKind int

const (
	// KindBad indicates that the Value has no type and should not be used.
	KindBad ValueKind = iota

	// KindUint64 indicates that the type of the Value is a uint64.
	KindUint64

	// KindFloat64 indicates that the type of the Value is a float64.
	KindFloat64

// AlgKind describes the kind of algorithms used for comparing and
// hashing a Type.
type AlgKind int8

//go:generate stringer -type AlgKind -trimprefix A alg.go

const (
	AUNK   AlgKind = iota
	ANOEQ          // Types cannot be compared
	ANOALG         // implies ANOEQ, and in addition has a part that is marked Noalg
	AMEM           // Type can be compared/hashed as regular memory.

	ObjFlagStd                      // standard library package
)

// Sym.Flag
const (
	SymFlagDupok = 1 << iota
	SymFlagLocal
	SymFlagTypelink
	SymFlagLeaf
	SymFlagNoSplit
	SymFlagReflectMethod
	SymFlagGoType
)

// Sym.Flag2
const (
	SymFlagUsedInIface = 1 << iota
	SymFlagItab
	SymFlagDict
	SymFlagPkgInit
	SymFlagLinkname
	SymFlagABIWrapper
)

	Parent        uint32
}

// CounterMode tracks the "flavor" of the coverage counters being
// used in a given coverage-instrumented program.
type CounterMode uint8

const (
	CtrModeInvalid  CounterMode = iota
	CtrModeSet                  // "set" mode
	CtrModeCount                // "count" mode
	CtrModeAtomic               // "atomic" mode
	CtrModeRegOnly              // registration-only pseudo-mode

type Arg interface {
	isArg()
	String() string
}

// A Reg is a single register.
// The zero value denotes W0, not the absence of a register.
type Reg uint16

const (
	W0 Reg = iota
	W1
	W2
	W3
	W4
	W5
	W6
	W7
	W8
	W9
	W10
	W11
	W12
	W13
	W14
	W15
	W16
	W17
	W18
	W19
	W20
	W21
	W22
	W23
	W24
	W25
	W26
	W27
	W28