import (
	"os"
	"runtime"
)

func foo(x int) int {
	return x + 1
}

func test() {
	defer func() {
		if r := recover(); r != nil {
			pcs := make([]uintptr, 10)
			n := runtime.Callers(0, pcs)
			pcs = pcs[:n]
			frames := runtime.CallersFrames(pcs)
			for {
				f, more := frames.Next()
				if f.Function == "main.foo" {
					println("did not expect to see call to foo in stack trace")
					os.Exit(1)
				}

	return sehf4(pan)
}

//go:noinline
func sehf4(pan bool) []uintptr {
	var pcs []uintptr
	if pan {
		panic("sehf4")
	}
	pcs = sehCallers()
	return pcs
}

func testSehCallersEqual(t *testing.T, pcs []uintptr, want []string) {
	t.Helper()
	got := make([]string, 0, len(want))
	for _, pc := range pcs {
		fn := runtime.FuncForPC(pc)
		if fn == nil || len(got) >= len(want) {
			break
		}

		"runtime_test.TestCallersPanic"}

	defer func() {
		if r := recover(); r == nil {
			t.Fatal("did not panic")
		}
		pcs := make([]uintptr, 20)
		pcs = pcs[:runtime.Callers(0, pcs)]
		testCallers(t, pcs, true)
		testCallersEqual(t, pcs, want)
	}()
	f1(true)
}

func TestCallersDoublePanic(t *testing.T) {
	// Make sure we don't have any extra frames on the stack (due to

var x byte
var p *byte

//go:noinline
func f() {
	q := p
	x = 11  // line 23
	*q = 12 // line 24
}
func main() {
	defer func() {
		recover()
		var pcs [10]uintptr
		n := runtime.Callers(1, pcs[:])
		frames := runtime.CallersFrames(pcs[:n])
		for {
			f, more := frames.Next()
			if f.Function == "main.f" && f.Line != 24 {
				panic(fmt.Errorf("expected line 24, got line %d", f.Line))
			}
			if !more {

// creating it if necessary.
func (c *StackCounter) Inc() {
	pcs := make([]uintptr, c.depth)
	n := runtime.Callers(2, pcs) // caller of Inc
	pcs = pcs[:n]

	c.mu.Lock()
	defer c.mu.Unlock()

	// Existing counter?
	var ctr *Counter
	for _, s := range c.stacks {
		if eq(s.pcs, pcs) {
			if s.counter != nil {
				ctr = s.counter
				break
			}
		}
	}

	if ctr == nil {

		return rec
	}
	// Slow path: the stack may still be in the map.

	// Grab the stack's PCs as the source-of-truth.
	var pcs [pprofMaxStack]uint64
	pcsForStack(stack, &pcs)

	// Check the source-of-truth.
	var rec *traceviewer.ProfileRecord
	if existing, ok := m.pcs[pcs]; ok {
		// In the map.
		rec = m.stacks[existing]
		delete(m.stacks, existing)
	} else {
		// Not in the map.

}

type locInfo struct {
	// location id assigned by the profileBuilder
	id uint64

	// sequence of PCs, including the fake PCs returned by the traceback
	// to represent inlined functions
	// https://github.com/golang/go/blob/d6f2f833c93a41ec1c68e49804b8387a06b131c5/src/runtime/traceback.go#L347-L368
	pcs []uintptr

	// firstPCFrames and firstPCSymbolizeResult hold the results of the

// walkFrames calls visit for each call frame represented by pcs.
//
// pcs should be a slice of PCs, as returned by runtime.Callers.
func walkFrames(pcs []uintptr, visit frameVisitor) {
	if len(pcs) == 0 {
		return
	}

	frames := runtime.CallersFrames(pcs)
	for {
		frame, more := frames.Next()
		visit(frame.File, frame.Line, frame.Function, frame.PC-frame.Entry)

type traceStackTable struct {
	tab traceMap
}

// put returns a unique id for the stack trace pcs and caches it in the table,
// if it sees the trace for the first time.
func (t *traceStackTable) put(pcs []uintptr) uint64 {
	if len(pcs) == 0 {
		return 0
	}
	id, _ := t.tab.put(noescape(unsafe.Pointer(&pcs[0])), uintptr(len(pcs))*unsafe.Sizeof(uintptr(0)))
	return id
}

package runtime_test

import (
	"fmt"
	"runtime"
	"strings"
)

func ExampleFrames() {
	c := func() {
		// Ask runtime.Callers for up to 10 PCs, including runtime.Callers itself.
		pc := make([]uintptr, 10)
		n := runtime.Callers(0, pc)
		if n == 0 {
			// No PCs available. This can happen if the first argument to
			// runtime.Callers is large.
			//
			// Return now to avoid processing the zero Frame that would