var n int
	systemstack(func() {
		var u unwinder
		u.initAt(pc, sp, 0, gp, unwindSilentErrors)
		n = tracebackPCs(&u, skip, pcbuf)
	})
	return n
}

func gcallers(gp *g, skip int, pcbuf []uintptr) int {
	var u unwinder
	u.init(gp, unwindSilentErrors)
	return tracebackPCs(&u, skip, pcbuf)
}

// showframe reports whether the frame with the given characteristics should

	}

	var nstk int
	gp := getg()
	sp := getcallersp()
	pc := getcallerpc()
	systemstack(func() {
		var u unwinder
		u.initAt(pc, sp, 0, gp, unwindSilentErrors|unwindJumpStack)
		nstk = 1 + tracebackPCs(&u, skip, prof.stack[1:])
	})
	if nstk < len(prof.stack) {
		prof.stack[nstk] = 0
	}
}

func (prof *mLockProfile) store() {
	// Report any contention we experience within this function as "lost"; it's

				snext := u.srcFunc(unext)
				if snext.funcID == abi.FuncIDWrapper && elideWrapperCalling(sf.funcID) {
					// Skip, because tracebackPCs (inside runtime.Callers) would too.
					continue
				}
				ci.nextPC = unext.pc + 1
				break
			}
		}
		ci.frames = append(ci.frames, Frame{
			PC:        pc,
			Func:      f,

func TracebackSystemstack(stk []uintptr, i int) int {
	if i == 0 {
		pc, sp := getcallerpc(), getcallersp()
		var u unwinder
		u.initAt(pc, sp, 0, getg(), unwindJumpStack) // Don't ignore errors, for testing
		return tracebackPCs(&u, 0, stk)
	}
	n := 0
	systemstack(func() {
		n = TracebackSystemstack(stk, i-1)
	})
	return n
}

func KeepNArenaHints(n int) {
	hint := mheap_.arenaHints
	for i := 1; i < n; i++ {

var traceback_cache uint32 = 2 << tracebackShift
var traceback_env uint32

// gotraceback returns the current traceback settings.
//
// If level is 0, suppress all tracebacks.
// If level is 1, show tracebacks, but exclude runtime frames.
// If level is 2, show tracebacks including runtime frames.
// If all is set, print all goroutine stacks. Otherwise, print just the current goroutine.
// If crash is set, crash (core dump, etc) after tracebacking.

		u.initAt(mp.vdsoPC, mp.vdsoSP, 0, gp, unwindSilentErrors|unwindJumpStack)
	} else {
		u.initAt(pc, sp, lr, gp, unwindSilentErrors|unwindTrap|unwindJumpStack)
	}
	n += tracebackPCs(&u, 0, stk[n:])

	if n <= 0 {
		// Normal traceback is impossible or has failed.
		// Account it against abstract "System" or "GC".
		n = 2
		if inVDSOPage(pc) {

// not be skipped if only -quick is used.
var flagQuick = flag.Bool("quick", false, "skip slow tests, for cmd/dist test runtime:cpu124")

func init() {
	// We're testing the runtime, so make tracebacks show things
	// in the runtime. This only raises the level, so it won't
	// override GOTRACEBACK=crash from the user.
	SetTracebackEnv("system")
}

var errf error

func errfn() error {
	return errf
}

}

// A ScopeID represents a lexical scope within a function.
type ScopeID int32

const (
	funcDupok      = 1 << iota // duplicate definitions ok
	funcWrapper                // hide frame from users (elide in tracebacks, don't count as a frame for recover())
	funcABIWrapper             // is an ABI wrapper (also set flagWrapper)
	funcNeedctxt               // function uses context register (has closure variables)

	schedtrace: setting schedtrace=X causes the scheduler to emit a single line to standard
	error every X milliseconds, summarizing the scheduler state.

	tracebackancestors: setting tracebackancestors=N extends tracebacks with the stacks at
	which goroutines were created, where N limits the number of ancestor goroutines to
	report. This also extends the information returned by runtime.Stack.
	Setting N to 0 will report no ancestry information.

// memory. It checks whether that Go memory contains any other
// pointer into unpinned Go memory. If it does, we panic.
// The return values are unused but useful to see in panic tracebacks.
func cgoCheckUnknownPointer(p unsafe.Pointer, msg string) (base, i uintptr) {
	if inheap(uintptr(p)) {
		b, span, _ := findObject(uintptr(p), 0, 0)
		base = b
		if base == 0 {
			return
		}