summaryrefslogtreecommitdiffstats
path: root/src/runtime/stack_test.go
blob: 600e80d8bfdba47c34e26fc7ae2cb58f9d26b33b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package runtime_test

import (
	"fmt"
	"internal/testenv"
	"reflect"
	"regexp"
	. "runtime"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"
	_ "unsafe" // for go:linkname
)

// TestStackMem measures per-thread stack segment cache behavior.
// The test consumed up to 500MB in the past.
func TestStackMem(t *testing.T) {
	const (
		BatchSize      = 32
		BatchCount     = 256
		ArraySize      = 1024
		RecursionDepth = 128
	)
	if testing.Short() {
		return
	}
	defer GOMAXPROCS(GOMAXPROCS(BatchSize))
	s0 := new(MemStats)
	ReadMemStats(s0)
	for b := 0; b < BatchCount; b++ {
		c := make(chan bool, BatchSize)
		for i := 0; i < BatchSize; i++ {
			go func() {
				var f func(k int, a [ArraySize]byte)
				f = func(k int, a [ArraySize]byte) {
					if k == 0 {
						time.Sleep(time.Millisecond)
						return
					}
					f(k-1, a)
				}
				f(RecursionDepth, [ArraySize]byte{})
				c <- true
			}()
		}
		for i := 0; i < BatchSize; i++ {
			<-c
		}

		// The goroutines have signaled via c that they are ready to exit.
		// Give them a chance to exit by sleeping. If we don't wait, we
		// might not reuse them on the next batch.
		time.Sleep(10 * time.Millisecond)
	}
	s1 := new(MemStats)
	ReadMemStats(s1)
	consumed := int64(s1.StackSys - s0.StackSys)
	t.Logf("Consumed %vMB for stack mem", consumed>>20)
	estimate := int64(8 * BatchSize * ArraySize * RecursionDepth) // 8 is to reduce flakiness.
	if consumed > estimate {
		t.Fatalf("Stack mem: want %v, got %v", estimate, consumed)
	}
	// Due to broken stack memory accounting (https://golang.org/issue/7468),
	// StackInuse can decrease during function execution, so we cast the values to int64.
	inuse := int64(s1.StackInuse) - int64(s0.StackInuse)
	t.Logf("Inuse %vMB for stack mem", inuse>>20)
	if inuse > 4<<20 {
		t.Fatalf("Stack inuse: want %v, got %v", 4<<20, inuse)
	}
}

// Test stack growing in different contexts.
func TestStackGrowth(t *testing.T) {
	if *flagQuick {
		t.Skip("-quick")
	}

	var wg sync.WaitGroup

	// in a normal goroutine
	var growDuration time.Duration // For debugging failures
	wg.Add(1)
	go func() {
		defer wg.Done()
		start := time.Now()
		growStack(nil)
		growDuration = time.Since(start)
	}()
	wg.Wait()
	t.Log("first growStack took", growDuration)

	// in locked goroutine
	wg.Add(1)
	go func() {
		defer wg.Done()
		LockOSThread()
		growStack(nil)
		UnlockOSThread()
	}()
	wg.Wait()

	// in finalizer
	var finalizerStart time.Time
	var started atomic.Bool
	var progress atomic.Uint32
	wg.Add(1)
	s := new(string) // Must be of a type that avoids the tiny allocator, or else the finalizer might not run.
	SetFinalizer(s, func(ss *string) {
		defer wg.Done()
		finalizerStart = time.Now()
		started.Store(true)
		growStack(&progress)
	})
	setFinalizerTime := time.Now()
	s = nil

	if d, ok := t.Deadline(); ok {
		// Pad the timeout by an arbitrary 5% to give the AfterFunc time to run.
		timeout := time.Until(d) * 19 / 20
		timer := time.AfterFunc(timeout, func() {
			// Panic — instead of calling t.Error and returning from the test — so
			// that we get a useful goroutine dump if the test times out, especially
			// if GOTRACEBACK=system or GOTRACEBACK=crash is set.
			if !started.Load() {
				panic("finalizer did not start")
			} else {
				panic(fmt.Sprintf("finalizer started %s ago (%s after registration) and ran %d iterations, but did not return", time.Since(finalizerStart), finalizerStart.Sub(setFinalizerTime), progress.Load()))
			}
		})
		defer timer.Stop()
	}

	GC()
	wg.Wait()
	t.Logf("finalizer started after %s and ran %d iterations in %v", finalizerStart.Sub(setFinalizerTime), progress.Load(), time.Since(finalizerStart))
}

// ... and in init
//func init() {
//	growStack()
//}

func growStack(progress *atomic.Uint32) {
	n := 1 << 10
	if testing.Short() {
		n = 1 << 8
	}
	for i := 0; i < n; i++ {
		x := 0
		growStackIter(&x, i)
		if x != i+1 {
			panic("stack is corrupted")
		}
		if progress != nil {
			progress.Store(uint32(i))
		}
	}
	GC()
}

// This function is not an anonymous func, so that the compiler can do escape
// analysis and place x on stack (and subsequently stack growth update the pointer).
func growStackIter(p *int, n int) {
	if n == 0 {
		*p = n + 1
		GC()
		return
	}
	*p = n + 1
	x := 0
	growStackIter(&x, n-1)
	if x != n {
		panic("stack is corrupted")
	}
}

func TestStackGrowthCallback(t *testing.T) {
	t.Parallel()
	var wg sync.WaitGroup

	// test stack growth at chan op
	wg.Add(1)
	go func() {
		defer wg.Done()
		c := make(chan int, 1)
		growStackWithCallback(func() {
			c <- 1
			<-c
		})
	}()

	// test stack growth at map op
	wg.Add(1)
	go func() {
		defer wg.Done()
		m := make(map[int]int)
		growStackWithCallback(func() {
			_, _ = m[1]
			m[1] = 1
		})
	}()

	// test stack growth at goroutine creation
	wg.Add(1)
	go func() {
		defer wg.Done()
		growStackWithCallback(func() {
			done := make(chan bool)
			go func() {
				done <- true
			}()
			<-done
		})
	}()
	wg.Wait()
}

func growStackWithCallback(cb func()) {
	var f func(n int)
	f = func(n int) {
		if n == 0 {
			cb()
			return
		}
		f(n - 1)
	}
	for i := 0; i < 1<<10; i++ {
		f(i)
	}
}

// TestDeferPtrs tests the adjustment of Defer's argument pointers (p aka &y)
// during a stack copy.
func set(p *int, x int) {
	*p = x
}
func TestDeferPtrs(t *testing.T) {
	var y int

	defer func() {
		if y != 42 {
			t.Errorf("defer's stack references were not adjusted appropriately")
		}
	}()
	defer set(&y, 42)
	growStack(nil)
}

type bigBuf [4 * 1024]byte

// TestDeferPtrsGoexit is like TestDeferPtrs but exercises the possibility that the
// stack grows as part of starting the deferred function. It calls Goexit at various
// stack depths, forcing the deferred function (with >4kB of args) to be run at
// the bottom of the stack. The goal is to find a stack depth less than 4kB from
// the end of the stack. Each trial runs in a different goroutine so that an earlier
// stack growth does not invalidate a later attempt.
func TestDeferPtrsGoexit(t *testing.T) {
	for i := 0; i < 100; i++ {
		c := make(chan int, 1)
		go testDeferPtrsGoexit(c, i)
		if n := <-c; n != 42 {
			t.Fatalf("defer's stack references were not adjusted appropriately (i=%d n=%d)", i, n)
		}
	}
}

func testDeferPtrsGoexit(c chan int, i int) {
	var y int
	defer func() {
		c <- y
	}()
	defer setBig(&y, 42, bigBuf{})
	useStackAndCall(i, Goexit)
}

func setBig(p *int, x int, b bigBuf) {
	*p = x
}

// TestDeferPtrsPanic is like TestDeferPtrsGoexit, but it's using panic instead
// of Goexit to run the Defers. Those two are different execution paths
// in the runtime.
func TestDeferPtrsPanic(t *testing.T) {
	for i := 0; i < 100; i++ {
		c := make(chan int, 1)
		go testDeferPtrsGoexit(c, i)
		if n := <-c; n != 42 {
			t.Fatalf("defer's stack references were not adjusted appropriately (i=%d n=%d)", i, n)
		}
	}
}

func testDeferPtrsPanic(c chan int, i int) {
	var y int
	defer func() {
		if recover() == nil {
			c <- -1
			return
		}
		c <- y
	}()
	defer setBig(&y, 42, bigBuf{})
	useStackAndCall(i, func() { panic(1) })
}

//go:noinline
func testDeferLeafSigpanic1() {
	// Cause a sigpanic to be injected in this frame.
	//
	// This function has to be declared before
	// TestDeferLeafSigpanic so the runtime will crash if we think
	// this function's continuation PC is in
	// TestDeferLeafSigpanic.
	*(*int)(nil) = 0
}

// TestDeferLeafSigpanic tests defer matching around leaf functions
// that sigpanic. This is tricky because on LR machines the outer
// function and the inner function have the same SP, but it's critical
// that we match up the defer correctly to get the right liveness map.
// See issue #25499.
func TestDeferLeafSigpanic(t *testing.T) {
	// Push a defer that will walk the stack.
	defer func() {
		if err := recover(); err == nil {
			t.Fatal("expected panic from nil pointer")
		}
		GC()
	}()
	// Call a leaf function. We must set up the exact call stack:
	//
	//  deferring function -> leaf function -> sigpanic
	//
	// On LR machines, the leaf function will have the same SP as
	// the SP pushed for the defer frame.
	testDeferLeafSigpanic1()
}

// TestPanicUseStack checks that a chain of Panic structs on the stack are
// updated correctly if the stack grows during the deferred execution that
// happens as a result of the panic.
func TestPanicUseStack(t *testing.T) {
	pc := make([]uintptr, 10000)
	defer func() {
		recover()
		Callers(0, pc) // force stack walk
		useStackAndCall(100, func() {
			defer func() {
				recover()
				Callers(0, pc) // force stack walk
				useStackAndCall(200, func() {
					defer func() {
						recover()
						Callers(0, pc) // force stack walk
					}()
					panic(3)
				})
			}()
			panic(2)
		})
	}()
	panic(1)
}

func TestPanicFar(t *testing.T) {
	var xtree *xtreeNode
	pc := make([]uintptr, 10000)
	defer func() {
		// At this point we created a large stack and unwound
		// it via recovery. Force a stack walk, which will
		// check the stack's consistency.
		Callers(0, pc)
	}()
	defer func() {
		recover()
	}()
	useStackAndCall(100, func() {
		// Kick off the GC and make it do something nontrivial.
		// (This used to force stack barriers to stick around.)
		xtree = makeTree(18)
		// Give the GC time to start scanning stacks.
		time.Sleep(time.Millisecond)
		panic(1)
	})
	_ = xtree
}

type xtreeNode struct {
	l, r *xtreeNode
}

func makeTree(d int) *xtreeNode {
	if d == 0 {
		return new(xtreeNode)
	}
	return &xtreeNode{makeTree(d - 1), makeTree(d - 1)}
}

// use about n KB of stack and call f
func useStackAndCall(n int, f func()) {
	if n == 0 {
		f()
		return
	}
	var b [1024]byte // makes frame about 1KB
	useStackAndCall(n-1+int(b[99]), f)
}

func useStack(n int) {
	useStackAndCall(n, func() {})
}

func growing(c chan int, done chan struct{}) {
	for n := range c {
		useStack(n)
		done <- struct{}{}
	}
	done <- struct{}{}
}

func TestStackCache(t *testing.T) {
	// Allocate a bunch of goroutines and grow their stacks.
	// Repeat a few times to test the stack cache.
	const (
		R = 4
		G = 200
		S = 5
	)
	for i := 0; i < R; i++ {
		var reqchans [G]chan int
		done := make(chan struct{})
		for j := 0; j < G; j++ {
			reqchans[j] = make(chan int)
			go growing(reqchans[j], done)
		}
		for s := 0; s < S; s++ {
			for j := 0; j < G; j++ {
				reqchans[j] <- 1 << uint(s)
			}
			for j := 0; j < G; j++ {
				<-done
			}
		}
		for j := 0; j < G; j++ {
			close(reqchans[j])
		}
		for j := 0; j < G; j++ {
			<-done
		}
	}
}

func TestStackOutput(t *testing.T) {
	b := make([]byte, 1024)
	stk := string(b[:Stack(b, false)])
	if !strings.HasPrefix(stk, "goroutine ") {
		t.Errorf("Stack (len %d):\n%s", len(stk), stk)
		t.Errorf("Stack output should begin with \"goroutine \"")
	}
}

func TestStackAllOutput(t *testing.T) {
	b := make([]byte, 1024)
	stk := string(b[:Stack(b, true)])
	if !strings.HasPrefix(stk, "goroutine ") {
		t.Errorf("Stack (len %d):\n%s", len(stk), stk)
		t.Errorf("Stack output should begin with \"goroutine \"")
	}
}

func TestStackPanic(t *testing.T) {
	// Test that stack copying copies panics correctly. This is difficult
	// to test because it is very unlikely that the stack will be copied
	// in the middle of gopanic. But it can happen.
	// To make this test effective, edit panic.go:gopanic and uncomment
	// the GC() call just before freedefer(d).
	defer func() {
		if x := recover(); x == nil {
			t.Errorf("recover failed")
		}
	}()
	useStack(32)
	panic("test panic")
}

func BenchmarkStackCopyPtr(b *testing.B) {
	c := make(chan bool)
	for i := 0; i < b.N; i++ {
		go func() {
			i := 1000000
			countp(&i)
			c <- true
		}()
		<-c
	}
}

func countp(n *int) {
	if *n == 0 {
		return
	}
	*n--
	countp(n)
}

func BenchmarkStackCopy(b *testing.B) {
	c := make(chan bool)
	for i := 0; i < b.N; i++ {
		go func() {
			count(1000000)
			c <- true
		}()
		<-c
	}
}

func count(n int) int {
	if n == 0 {
		return 0
	}
	return 1 + count(n-1)
}

func BenchmarkStackCopyNoCache(b *testing.B) {
	c := make(chan bool)
	for i := 0; i < b.N; i++ {
		go func() {
			count1(1000000)
			c <- true
		}()
		<-c
	}
}

func count1(n int) int {
	if n <= 0 {
		return 0
	}
	return 1 + count2(n-1)
}

func count2(n int) int  { return 1 + count3(n-1) }
func count3(n int) int  { return 1 + count4(n-1) }
func count4(n int) int  { return 1 + count5(n-1) }
func count5(n int) int  { return 1 + count6(n-1) }
func count6(n int) int  { return 1 + count7(n-1) }
func count7(n int) int  { return 1 + count8(n-1) }
func count8(n int) int  { return 1 + count9(n-1) }
func count9(n int) int  { return 1 + count10(n-1) }
func count10(n int) int { return 1 + count11(n-1) }
func count11(n int) int { return 1 + count12(n-1) }
func count12(n int) int { return 1 + count13(n-1) }
func count13(n int) int { return 1 + count14(n-1) }
func count14(n int) int { return 1 + count15(n-1) }
func count15(n int) int { return 1 + count16(n-1) }
func count16(n int) int { return 1 + count17(n-1) }
func count17(n int) int { return 1 + count18(n-1) }
func count18(n int) int { return 1 + count19(n-1) }
func count19(n int) int { return 1 + count20(n-1) }
func count20(n int) int { return 1 + count21(n-1) }
func count21(n int) int { return 1 + count22(n-1) }
func count22(n int) int { return 1 + count23(n-1) }
func count23(n int) int { return 1 + count1(n-1) }

type stkobjT struct {
	p *stkobjT
	x int64
	y [20]int // consume some stack
}

// Sum creates a linked list of stkobjTs.
func Sum(n int64, p *stkobjT) {
	if n == 0 {
		return
	}
	s := stkobjT{p: p, x: n}
	Sum(n-1, &s)
	p.x += s.x
}

func BenchmarkStackCopyWithStkobj(b *testing.B) {
	c := make(chan bool)
	for i := 0; i < b.N; i++ {
		go func() {
			var s stkobjT
			Sum(100000, &s)
			c <- true
		}()
		<-c
	}
}

func BenchmarkIssue18138(b *testing.B) {
	// Channel with N "can run a goroutine" tokens
	const N = 10
	c := make(chan []byte, N)
	for i := 0; i < N; i++ {
		c <- make([]byte, 1)
	}

	for i := 0; i < b.N; i++ {
		<-c // get token
		go func() {
			useStackPtrs(1000, false) // uses ~1MB max
			m := make([]byte, 8192)   // make GC trigger occasionally
			c <- m                    // return token
		}()
	}
}

func useStackPtrs(n int, b bool) {
	if b {
		// This code contributes to the stack frame size, and hence to the
		// stack copying cost. But since b is always false, it costs no
		// execution time (not even the zeroing of a).
		var a [128]*int // 1KB of pointers
		a[n] = &n
		n = *a[0]
	}
	if n == 0 {
		return
	}
	useStackPtrs(n-1, b)
}

type structWithMethod struct{}

func (s structWithMethod) caller() string {
	_, file, line, ok := Caller(1)
	if !ok {
		panic("Caller failed")
	}
	return fmt.Sprintf("%s:%d", file, line)
}

func (s structWithMethod) callers() []uintptr {
	pc := make([]uintptr, 16)
	return pc[:Callers(0, pc)]
}

func (s structWithMethod) stack() string {
	buf := make([]byte, 4<<10)
	return string(buf[:Stack(buf, false)])
}

func (s structWithMethod) nop() {}

func (s structWithMethod) inlinablePanic() { panic("panic") }

func TestStackWrapperCaller(t *testing.T) {
	var d structWithMethod
	// Force the compiler to construct a wrapper method.
	wrapper := (*structWithMethod).caller
	// Check that the wrapper doesn't affect the stack trace.
	if dc, ic := d.caller(), wrapper(&d); dc != ic {
		t.Fatalf("direct caller %q != indirect caller %q", dc, ic)
	}
}

func TestStackWrapperCallers(t *testing.T) {
	var d structWithMethod
	wrapper := (*structWithMethod).callers
	// Check that <autogenerated> doesn't appear in the stack trace.
	pcs := wrapper(&d)
	frames := CallersFrames(pcs)
	for {
		fr, more := frames.Next()
		if fr.File == "<autogenerated>" {
			t.Fatalf("<autogenerated> appears in stack trace: %+v", fr)
		}
		if !more {
			break
		}
	}
}

func TestStackWrapperStack(t *testing.T) {
	var d structWithMethod
	wrapper := (*structWithMethod).stack
	// Check that <autogenerated> doesn't appear in the stack trace.
	stk := wrapper(&d)
	if strings.Contains(stk, "<autogenerated>") {
		t.Fatalf("<autogenerated> appears in stack trace:\n%s", stk)
	}
}

func TestStackWrapperStackInlinePanic(t *testing.T) {
	// Test that inline unwinding correctly tracks the callee by creating a
	// stack of the form wrapper -> inlined function -> panic. If we mess up
	// callee tracking, it will look like the wrapper called panic and we'll see
	// the wrapper in the stack trace.
	var d structWithMethod
	wrapper := (*structWithMethod).inlinablePanic
	defer func() {
		err := recover()
		if err == nil {
			t.Fatalf("expected panic")
		}
		buf := make([]byte, 4<<10)
		stk := string(buf[:Stack(buf, false)])
		if strings.Contains(stk, "<autogenerated>") {
			t.Fatalf("<autogenerated> appears in stack trace:\n%s", stk)
		}
		// Self-check: make sure inlinablePanic got inlined.
		if !testenv.OptimizationOff() {
			if !strings.Contains(stk, "inlinablePanic(...)") {
				t.Fatalf("inlinablePanic not inlined")
			}
		}
	}()
	wrapper(&d)
}

type I interface {
	M()
}

func TestStackWrapperStackPanic(t *testing.T) {
	t.Run("sigpanic", func(t *testing.T) {
		// nil calls to interface methods cause a sigpanic.
		testStackWrapperPanic(t, func() { I.M(nil) }, "runtime_test.I.M")
	})
	t.Run("panicwrap", func(t *testing.T) {
		// Nil calls to value method wrappers call panicwrap.
		wrapper := (*structWithMethod).nop
		testStackWrapperPanic(t, func() { wrapper(nil) }, "runtime_test.(*structWithMethod).nop")
	})
}

func testStackWrapperPanic(t *testing.T, cb func(), expect string) {
	// Test that the stack trace from a panicking wrapper includes
	// the wrapper, even though elide these when they don't panic.
	t.Run("CallersFrames", func(t *testing.T) {
		defer func() {
			err := recover()
			if err == nil {
				t.Fatalf("expected panic")
			}
			pcs := make([]uintptr, 10)
			n := Callers(0, pcs)
			frames := CallersFrames(pcs[:n])
			for {
				frame, more := frames.Next()
				t.Log(frame.Function)
				if frame.Function == expect {
					return
				}
				if !more {
					break
				}
			}
			t.Fatalf("panicking wrapper %s missing from stack trace", expect)
		}()
		cb()
	})
	t.Run("Stack", func(t *testing.T) {
		defer func() {
			err := recover()
			if err == nil {
				t.Fatalf("expected panic")
			}
			buf := make([]byte, 4<<10)
			stk := string(buf[:Stack(buf, false)])
			if !strings.Contains(stk, "\n"+expect) {
				t.Fatalf("panicking wrapper %s missing from stack trace:\n%s", expect, stk)
			}
		}()
		cb()
	})
}

func TestCallersFromWrapper(t *testing.T) {
	// Test that invoking CallersFrames on a stack where the first
	// PC is an autogenerated wrapper keeps the wrapper in the
	// trace. Normally we elide these, assuming that the wrapper
	// calls the thing you actually wanted to see, but in this
	// case we need to keep it.
	pc := reflect.ValueOf(I.M).Pointer()
	frames := CallersFrames([]uintptr{pc})
	frame, more := frames.Next()
	if frame.Function != "runtime_test.I.M" {
		t.Fatalf("want function %s, got %s", "runtime_test.I.M", frame.Function)
	}
	if more {
		t.Fatalf("want 1 frame, got > 1")
	}
}

func TestTracebackSystemstack(t *testing.T) {
	if GOARCH == "ppc64" || GOARCH == "ppc64le" {
		t.Skip("systemstack tail call not implemented on ppc64x")
	}

	// Test that profiles correctly jump over systemstack,
	// including nested systemstack calls.
	pcs := make([]uintptr, 20)
	pcs = pcs[:TracebackSystemstack(pcs, 5)]
	// Check that runtime.TracebackSystemstack appears five times
	// and that we see TestTracebackSystemstack.
	countIn, countOut := 0, 0
	frames := CallersFrames(pcs)
	var tb strings.Builder
	for {
		frame, more := frames.Next()
		fmt.Fprintf(&tb, "\n%s+0x%x %s:%d", frame.Function, frame.PC-frame.Entry, frame.File, frame.Line)
		switch frame.Function {
		case "runtime.TracebackSystemstack":
			countIn++
		case "runtime_test.TestTracebackSystemstack":
			countOut++
		}
		if !more {
			break
		}
	}
	if countIn != 5 || countOut != 1 {
		t.Fatalf("expected 5 calls to TracebackSystemstack and 1 call to TestTracebackSystemstack, got:%s", tb.String())
	}
}

func TestTracebackAncestors(t *testing.T) {
	goroutineRegex := regexp.MustCompile(`goroutine [0-9]+ \[`)
	for _, tracebackDepth := range []int{0, 1, 5, 50} {
		output := runTestProg(t, "testprog", "TracebackAncestors", fmt.Sprintf("GODEBUG=tracebackancestors=%d", tracebackDepth))

		numGoroutines := 3
		numFrames := 2
		ancestorsExpected := numGoroutines
		if numGoroutines > tracebackDepth {
			ancestorsExpected = tracebackDepth
		}

		matches := goroutineRegex.FindAllStringSubmatch(output, -1)
		if len(matches) != 2 {
			t.Fatalf("want 2 goroutines, got:\n%s", output)
		}

		// Check functions in the traceback.
		fns := []string{"main.recurseThenCallGo", "main.main", "main.printStack", "main.TracebackAncestors"}
		for _, fn := range fns {
			if !strings.Contains(output, "\n"+fn+"(") {
				t.Fatalf("expected %q function in traceback:\n%s", fn, output)
			}
		}

		if want, count := "originating from goroutine", ancestorsExpected; strings.Count(output, want) != count {
			t.Errorf("output does not contain %d instances of %q:\n%s", count, want, output)
		}

		if want, count := "main.recurseThenCallGo(...)", ancestorsExpected*(numFrames+1); strings.Count(output, want) != count {
			t.Errorf("output does not contain %d instances of %q:\n%s", count, want, output)
		}

		if want, count := "main.recurseThenCallGo(0x", 1; strings.Count(output, want) != count {
			t.Errorf("output does not contain %d instances of %q:\n%s", count, want, output)
		}
	}
}

// Test that defer closure is correctly scanned when the stack is scanned.
func TestDeferLiveness(t *testing.T) {
	output := runTestProg(t, "testprog", "DeferLiveness", "GODEBUG=clobberfree=1")
	if output != "" {
		t.Errorf("output:\n%s\n\nwant no output", output)
	}
}

func TestDeferHeapAndStack(t *testing.T) {
	P := 4     // processors
	N := 10000 //iterations
	D := 200   // stack depth

	if testing.Short() {
		P /= 2
		N /= 10
		D /= 10
	}
	c := make(chan bool)
	for p := 0; p < P; p++ {
		go func() {
			for i := 0; i < N; i++ {
				if deferHeapAndStack(D) != 2*D {
					panic("bad result")
				}
			}
			c <- true
		}()
	}
	for p := 0; p < P; p++ {
		<-c
	}
}

// deferHeapAndStack(n) computes 2*n
func deferHeapAndStack(n int) (r int) {
	if n == 0 {
		return 0
	}
	if n%2 == 0 {
		// heap-allocated defers
		for i := 0; i < 2; i++ {
			defer func() {
				r++
			}()
		}
	} else {
		// stack-allocated defers
		defer func() {
			r++
		}()
		defer func() {
			r++
		}()
	}
	r = deferHeapAndStack(n - 1)
	escapeMe(new([1024]byte)) // force some GCs
	return
}

// Pass a value to escapeMe to force it to escape.
var escapeMe = func(x any) {}

func TestFramePointerAdjust(t *testing.T) {
	switch GOARCH {
	case "amd64", "arm64":
	default:
		t.Skipf("frame pointer is not supported on %s", GOARCH)
	}
	output := runTestProg(t, "testprog", "FramePointerAdjust")
	if output != "" {
		t.Errorf("output:\n%s\n\nwant no output", output)
	}
}

// TestSystemstackFramePointerAdjust is a regression test for issue 59692 that
// ensures that the frame pointer of systemstack is correctly adjusted. See CL
// 489015 for more details.
func TestSystemstackFramePointerAdjust(t *testing.T) {
	growAndShrinkStack(512, [1024]byte{})
}

// growAndShrinkStack grows the stack of the current goroutine in order to
// shrink it again and verify that all frame pointers on the new stack have
// been correctly adjusted. stackBallast is used to ensure we're not depending
// on the current heuristics of stack shrinking too much.
func growAndShrinkStack(n int, stackBallast [1024]byte) {
	if n <= 0 {
		return
	}
	growAndShrinkStack(n-1, stackBallast)
	ShrinkStackAndVerifyFramePointers()
}