traceback_test.go

     1  // Copyright 2021 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime_test
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"internal/abi"
    11  	"internal/testenv"
    12  	"regexp"
    13  	"runtime"
    14  	"runtime/debug"
    15  	"strconv"
    16  	"strings"
    17  	"sync"
    18  	"testing"
    19  	_ "unsafe"
    20  )
    21  
    22  // Test traceback printing of inlined frames.
    23  func TestTracebackInlined(t *testing.T) {
    24  	testenv.SkipIfOptimizationOff(t) // This test requires inlining
    25  	check := func(t *testing.T, r *ttiResult, funcs ...string) {
    26  		t.Helper()
    27  
    28  		// Check the printed traceback.
    29  		frames := parseTraceback1(t, r.printed).frames
    30  		t.Log(r.printed)
    31  		// Find ttiLeaf
    32  		for len(frames) > 0 && frames[0].funcName != "runtime_test.ttiLeaf" {
    33  			frames = frames[1:]
    34  		}
    35  		if len(frames) == 0 {
    36  			t.Errorf("missing runtime_test.ttiLeaf")
    37  			return
    38  		}
    39  		frames = frames[1:]
    40  		// Check the function sequence.
    41  		for i, want := range funcs {
    42  			got := "<end>"
    43  			if i < len(frames) {
    44  				got = frames[i].funcName
    45  				if strings.HasSuffix(want, ")") {
    46  					got += "(" + frames[i].args + ")"
    47  				}
    48  			}
    49  			if got != want {
    50  				t.Errorf("got %s, want %s", got, want)
    51  				return
    52  			}
    53  		}
    54  	}
    55  
    56  	t.Run("simple", func(t *testing.T) {
    57  		// Check a simple case of inlining
    58  		r := ttiSimple1()
    59  		check(t, r, "runtime_test.ttiSimple3(...)", "runtime_test.ttiSimple2(...)", "runtime_test.ttiSimple1()")
    60  	})
    61  
    62  	t.Run("sigpanic", func(t *testing.T) {
    63  		// Check that sigpanic from an inlined function prints correctly
    64  		r := ttiSigpanic1()
    65  		check(t, r, "runtime_test.ttiSigpanic1.func1()", "panic", "runtime_test.ttiSigpanic3(...)", "runtime_test.ttiSigpanic2(...)", "runtime_test.ttiSigpanic1()")
    66  	})
    67  
    68  	t.Run("wrapper", func(t *testing.T) {
    69  		// Check that a method inlined into a wrapper prints correctly
    70  		r := ttiWrapper1()
    71  		check(t, r, "runtime_test.ttiWrapper.m1(...)", "runtime_test.ttiWrapper1()")
    72  	})
    73  
    74  	t.Run("excluded", func(t *testing.T) {
    75  		// Check that when F -> G is inlined and F is excluded from stack
    76  		// traces, G still appears.
    77  		r := ttiExcluded1()
    78  		check(t, r, "runtime_test.ttiExcluded3(...)", "runtime_test.ttiExcluded1()")
    79  	})
    80  }
    81  
    82  type ttiResult struct {
    83  	printed string
    84  }
    85  
    86  //go:noinline
    87  func ttiLeaf() *ttiResult {
    88  	// Get a printed stack trace.
    89  	printed := string(debug.Stack())
    90  	return &ttiResult{printed}
    91  }
    92  
    93  //go:noinline
    94  func ttiSimple1() *ttiResult {
    95  	return ttiSimple2()
    96  }
    97  func ttiSimple2() *ttiResult {
    98  	return ttiSimple3()
    99  }
   100  func ttiSimple3() *ttiResult {
   101  	return ttiLeaf()
   102  }
   103  
   104  //go:noinline
   105  func ttiSigpanic1() (res *ttiResult) {
   106  	defer func() {
   107  		res = ttiLeaf()
   108  		recover()
   109  	}()
   110  	ttiSigpanic2()
   111  	// without condition below the inliner might decide to de-prioritize
   112  	// the callsite above (since it would be on an "always leads to panic"
   113  	// path).
   114  	if alwaysTrue {
   115  		panic("did not panic")
   116  	}
   117  	return nil
   118  }
   119  func ttiSigpanic2() {
   120  	ttiSigpanic3()
   121  }
   122  func ttiSigpanic3() {
   123  	var p *int
   124  	*p = 3
   125  }
   126  
   127  var alwaysTrue = true
   128  
   129  //go:noinline
   130  func ttiWrapper1() *ttiResult {
   131  	var w ttiWrapper
   132  	m := (*ttiWrapper).m1
   133  	return m(&w)
   134  }
   135  
   136  type ttiWrapper struct{}
   137  
   138  func (w ttiWrapper) m1() *ttiResult {
   139  	return ttiLeaf()
   140  }
   141  
   142  //go:noinline
   143  func ttiExcluded1() *ttiResult {
   144  	return ttiExcluded2()
   145  }
   146  
   147  // ttiExcluded2 should be excluded from tracebacks. There are
   148  // various ways this could come up. Linking it to a "runtime." name is
   149  // rather synthetic, but it's easy and reliable. See issue #42754 for
   150  // one way this happened in real code.
   151  //
   152  //go:linkname ttiExcluded2 runtime.ttiExcluded2
   153  //go:noinline
   154  func ttiExcluded2() *ttiResult {
   155  	return ttiExcluded3()
   156  }
   157  func ttiExcluded3() *ttiResult {
   158  	return ttiLeaf()
   159  }
   160  
   161  var testTracebackArgsBuf [1000]byte
   162  
   163  func TestTracebackElision(t *testing.T) {
   164  	// Test printing exactly the maximum number of frames to make sure we don't
   165  	// print any "elided" message, eliding exactly 1 so we have to pick back up
   166  	// in the paused physical frame, and eliding 10 so we have to advance the
   167  	// physical frame forward.
   168  	for _, elided := range []int{0, 1, 10} {
   169  		t.Run(fmt.Sprintf("elided=%d", elided), func(t *testing.T) {
   170  			n := elided + runtime.TracebackInnerFrames + runtime.TracebackOuterFrames
   171  
   172  			// Start a new goroutine so we have control over the whole stack.
   173  			stackChan := make(chan string)
   174  			go tteStack(n, stackChan)
   175  			stack := <-stackChan
   176  			tb := parseTraceback1(t, stack)
   177  
   178  			// Check the traceback.
   179  			i := 0
   180  			for i < n {
   181  				if len(tb.frames) == 0 {
   182  					t.Errorf("traceback ended early")
   183  					break
   184  				}
   185  				fr := tb.frames[0]
   186  				if i == runtime.TracebackInnerFrames && elided > 0 {
   187  					// This should be an "elided" frame.
   188  					if fr.elided != elided {
   189  						t.Errorf("want %d frames elided", elided)
   190  						break
   191  					}
   192  					i += fr.elided
   193  				} else {
   194  					want := fmt.Sprintf("runtime_test.tte%d", (i+1)%5)
   195  					if i == 0 {
   196  						want = "runtime/debug.Stack"
   197  					} else if i == n-1 {
   198  						want = "runtime_test.tteStack"
   199  					}
   200  					if fr.funcName != want {
   201  						t.Errorf("want %s, got %s", want, fr.funcName)
   202  						break
   203  					}
   204  					i++
   205  				}
   206  				tb.frames = tb.frames[1:]
   207  			}
   208  			if !t.Failed() && len(tb.frames) > 0 {
   209  				t.Errorf("got %d more frames than expected", len(tb.frames))
   210  			}
   211  			if t.Failed() {
   212  				t.Logf("traceback diverged at frame %d", i)
   213  				off := len(stack)
   214  				if len(tb.frames) > 0 {
   215  					off = tb.frames[0].off
   216  				}
   217  				t.Logf("traceback before error:\n%s", stack[:off])
   218  				t.Logf("traceback after error:\n%s", stack[off:])
   219  			}
   220  		})
   221  	}
   222  }
   223  
   224  // tteStack creates a stack of n logical frames and sends the traceback to
   225  // stack. It cycles through 5 logical frames per physical frame to make it
   226  // unlikely that any part of the traceback will end on a physical boundary.
   227  func tteStack(n int, stack chan<- string) {
   228  	n-- // Account for this frame
   229  	// This is basically a Duff's device for starting the inline stack in the
   230  	// right place so we wind up at tteN when n%5=N.
   231  	switch n % 5 {
   232  	case 0:
   233  		stack <- tte0(n)
   234  	case 1:
   235  		stack <- tte1(n)
   236  	case 2:
   237  		stack <- tte2(n)
   238  	case 3:
   239  		stack <- tte3(n)
   240  	case 4:
   241  		stack <- tte4(n)
   242  	default:
   243  		panic("unreachable")
   244  	}
   245  }
   246  func tte0(n int) string {
   247  	return tte4(n - 1)
   248  }
   249  func tte1(n int) string {
   250  	return tte0(n - 1)
   251  }
   252  func tte2(n int) string {
   253  	// tte2 opens n%5 == 2 frames. It's also the base case of the recursion,
   254  	// since we can open no fewer than two frames to call debug.Stack().
   255  	if n < 2 {
   256  		panic("bad n")
   257  	}
   258  	if n == 2 {
   259  		return string(debug.Stack())
   260  	}
   261  	return tte1(n - 1)
   262  }
   263  func tte3(n int) string {
   264  	return tte2(n - 1)
   265  }
   266  func tte4(n int) string {
   267  	return tte3(n - 1)
   268  }
   269  
   270  func TestTracebackArgs(t *testing.T) {
   271  	if *flagQuick {
   272  		t.Skip("-quick")
   273  	}
   274  	optimized := !testenv.OptimizationOff()
   275  	abiSel := func(x, y string) string {
   276  		// select expected output based on ABI
   277  		// In noopt build we always spill arguments so the output is the same as stack ABI.
   278  		if optimized && abi.IntArgRegs > 0 {
   279  			return x
   280  		}
   281  		return y
   282  	}
   283  
   284  	tests := []struct {
   285  		fn     func() int
   286  		expect string
   287  	}{
   288  		// simple ints
   289  		{
   290  			func() int { return testTracebackArgs1(1, 2, 3, 4, 5) },
   291  			"testTracebackArgs1(0x1, 0x2, 0x3, 0x4, 0x5)",
   292  		},
   293  		// some aggregates
   294  		{
   295  			func() int {
   296  				return testTracebackArgs2(false, struct {
   297  					a, b, c int
   298  					x       [2]int
   299  				}{1, 2, 3, [2]int{4, 5}}, [0]int{}, [3]byte{6, 7, 8})
   300  			},
   301  			"testTracebackArgs2(0x0, {0x1, 0x2, 0x3, {0x4, 0x5}}, {}, {0x6, 0x7, 0x8})",
   302  		},
   303  		{
   304  			func() int { return testTracebackArgs3([3]byte{1, 2, 3}, 4, 5, 6, [3]byte{7, 8, 9}) },
   305  			"testTracebackArgs3({0x1, 0x2, 0x3}, 0x4, 0x5, 0x6, {0x7, 0x8, 0x9})",
   306  		},
   307  		// too deeply nested type
   308  		{
   309  			func() int { return testTracebackArgs4(false, [1][1][1][1][1][1][1][1][1][1]int{}) },
   310  			"testTracebackArgs4(0x0, {{{{{...}}}}})",
   311  		},
   312  		// a lot of zero-sized type
   313  		{
   314  			func() int {
   315  				z := [0]int{}
   316  				return testTracebackArgs5(false, struct {
   317  					x int
   318  					y [0]int
   319  					z [2][0]int
   320  				}{1, z, [2][0]int{}}, z, z, z, z, z, z, z, z, z, z, z, z)
   321  			},
   322  			"testTracebackArgs5(0x0, {0x1, {}, {{}, {}}}, {}, {}, {}, {}, {}, ...)",
   323  		},
   324  
   325  		// edge cases for ...
   326  		// no ... for 10 args
   327  		{
   328  			func() int { return testTracebackArgs6a(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) },
   329  			"testTracebackArgs6a(0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa)",
   330  		},
   331  		// has ... for 11 args
   332  		{
   333  			func() int { return testTracebackArgs6b(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) },
   334  			"testTracebackArgs6b(0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, ...)",
   335  		},
   336  		// no ... for aggregates with 10 words
   337  		{
   338  			func() int { return testTracebackArgs7a([10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) },
   339  			"testTracebackArgs7a({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa})",
   340  		},
   341  		// has ... for aggregates with 11 words
   342  		{
   343  			func() int { return testTracebackArgs7b([11]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}) },
   344  			"testTracebackArgs7b({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, ...})",
   345  		},
   346  		// no ... for aggregates, but with more args
   347  		{
   348  			func() int { return testTracebackArgs7c([10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, 11) },
   349  			"testTracebackArgs7c({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa}, ...)",
   350  		},
   351  		// has ... for aggregates and also for more args
   352  		{
   353  			func() int { return testTracebackArgs7d([11]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}, 12) },
   354  			"testTracebackArgs7d({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, ...}, ...)",
   355  		},
   356  		// nested aggregates, no ...
   357  		{
   358  			func() int { return testTracebackArgs8a(testArgsType8a{1, 2, 3, 4, 5, 6, 7, 8, [2]int{9, 10}}) },
   359  			"testTracebackArgs8a({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa}})",
   360  		},
   361  		// nested aggregates, ... in inner but not outer
   362  		{
   363  			func() int { return testTracebackArgs8b(testArgsType8b{1, 2, 3, 4, 5, 6, 7, 8, [3]int{9, 10, 11}}) },
   364  			"testTracebackArgs8b({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa, ...}})",
   365  		},
   366  		// nested aggregates, ... in outer but not inner
   367  		{
   368  			func() int { return testTracebackArgs8c(testArgsType8c{1, 2, 3, 4, 5, 6, 7, 8, [2]int{9, 10}, 11}) },
   369  			"testTracebackArgs8c({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa}, ...})",
   370  		},
   371  		// nested aggregates, ... in both inner and outer
   372  		{
   373  			func() int { return testTracebackArgs8d(testArgsType8d{1, 2, 3, 4, 5, 6, 7, 8, [3]int{9, 10, 11}, 12}) },
   374  			"testTracebackArgs8d({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa, ...}, ...})",
   375  		},
   376  
   377  		// Register argument liveness.
   378  		// 1, 3 are used and live, 2, 4 are dead (in register ABI).
   379  		// Address-taken (7) and stack ({5, 6}) args are always live.
   380  		{
   381  			func() int {
   382  				poisonStack() // poison arg area to make output deterministic
   383  				return testTracebackArgs9(1, 2, 3, 4, [2]int{5, 6}, 7)
   384  			},
   385  			abiSel(
   386  				"testTracebackArgs9(0x1, 0xffffffff?, 0x3, 0xff?, {0x5, 0x6}, 0x7)",
   387  				"testTracebackArgs9(0x1, 0x2, 0x3, 0x4, {0x5, 0x6}, 0x7)"),
   388  		},
   389  		// No live.
   390  		// (Note: this assume at least 5 int registers if register ABI is used.)
   391  		{
   392  			func() int {
   393  				poisonStack() // poison arg area to make output deterministic
   394  				return testTracebackArgs10(1, 2, 3, 4, 5)
   395  			},
   396  			abiSel(
   397  				"testTracebackArgs10(0xffffffff?, 0xffffffff?, 0xffffffff?, 0xffffffff?, 0xffffffff?)",
   398  				"testTracebackArgs10(0x1, 0x2, 0x3, 0x4, 0x5)"),
   399  		},
   400  		// Conditional spills.
   401  		// Spill in conditional, not executed.
   402  		{
   403  			func() int {
   404  				poisonStack() // poison arg area to make output deterministic
   405  				return testTracebackArgs11a(1, 2, 3)
   406  			},
   407  			abiSel(
   408  				"testTracebackArgs11a(0xffffffff?, 0xffffffff?, 0xffffffff?)",
   409  				"testTracebackArgs11a(0x1, 0x2, 0x3)"),
   410  		},
   411  		// 2 spills in conditional, not executed; 3 spills in conditional, executed, but not statically known.
   412  		// So print 0x3?.
   413  		{
   414  			func() int {
   415  				poisonStack() // poison arg area to make output deterministic
   416  				return testTracebackArgs11b(1, 2, 3, 4)
   417  			},
   418  			abiSel(
   419  				"testTracebackArgs11b(0xffffffff?, 0xffffffff?, 0x3?, 0x4)",
   420  				"testTracebackArgs11b(0x1, 0x2, 0x3, 0x4)"),
   421  		},
   422  		// Make sure spilled slice data pointers are spilled to the right location
   423  		// to ensure we see it listed without a ?.
   424  		// See issue 64414.
   425  		{
   426  			func() int {
   427  				poisonStack()
   428  				return testTracebackArgsSlice(testTracebackArgsSliceBackingStore[:])
   429  			},
   430  			// Note: capacity of the slice might be junk, as it is not used.
   431  			fmt.Sprintf("testTracebackArgsSlice({%p, 0x2, ", &testTracebackArgsSliceBackingStore[0]),
   432  		},
   433  	}
   434  	for _, test := range tests {
   435  		n := test.fn()
   436  		got := testTracebackArgsBuf[:n]
   437  		if !bytes.Contains(got, []byte(test.expect)) {
   438  			t.Errorf("traceback does not contain expected string: want %q, got\n%s", test.expect, got)
   439  		}
   440  	}
   441  }
   442  
   443  //go:noinline
   444  func testTracebackArgs1(a, b, c, d, e int) int {
   445  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   446  	if a < 0 {
   447  		// use in-reg args to keep them alive
   448  		return a + b + c + d + e
   449  	}
   450  	return n
   451  }
   452  
   453  //go:noinline
   454  func testTracebackArgs2(a bool, b struct {
   455  	a, b, c int
   456  	x       [2]int
   457  }, _ [0]int, d [3]byte) int {
   458  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   459  	if a {
   460  		// use in-reg args to keep them alive
   461  		return b.a + b.b + b.c + b.x[0] + b.x[1] + int(d[0]) + int(d[1]) + int(d[2])
   462  	}
   463  	return n
   464  }
   465  
   466  //go:noinline
   467  //go:registerparams
   468  func testTracebackArgs3(x [3]byte, a, b, c int, y [3]byte) int {
   469  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   470  	if a < 0 {
   471  		// use in-reg args to keep them alive
   472  		return int(x[0]) + int(x[1]) + int(x[2]) + a + b + c + int(y[0]) + int(y[1]) + int(y[2])
   473  	}
   474  	return n
   475  }
   476  
   477  //go:noinline
   478  func testTracebackArgs4(a bool, x [1][1][1][1][1][1][1][1][1][1]int) int {
   479  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   480  	if a {
   481  		panic(x) // use args to keep them alive
   482  	}
   483  	return n
   484  }
   485  
   486  //go:noinline
   487  func testTracebackArgs5(a bool, x struct {
   488  	x int
   489  	y [0]int
   490  	z [2][0]int
   491  }, _, _, _, _, _, _, _, _, _, _, _, _ [0]int) int {
   492  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   493  	if a {
   494  		panic(x) // use args to keep them alive
   495  	}
   496  	return n
   497  }
   498  
   499  //go:noinline
   500  func testTracebackArgs6a(a, b, c, d, e, f, g, h, i, j int) int {
   501  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   502  	if a < 0 {
   503  		// use in-reg args to keep them alive
   504  		return a + b + c + d + e + f + g + h + i + j
   505  	}
   506  	return n
   507  }
   508  
   509  //go:noinline
   510  func testTracebackArgs6b(a, b, c, d, e, f, g, h, i, j, k int) int {
   511  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   512  	if a < 0 {
   513  		// use in-reg args to keep them alive
   514  		return a + b + c + d + e + f + g + h + i + j + k
   515  	}
   516  	return n
   517  }
   518  
   519  //go:noinline
   520  func testTracebackArgs7a(a [10]int) int {
   521  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   522  	if a[0] < 0 {
   523  		// use in-reg args to keep them alive
   524  		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9]
   525  	}
   526  	return n
   527  }
   528  
   529  //go:noinline
   530  func testTracebackArgs7b(a [11]int) int {
   531  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   532  	if a[0] < 0 {
   533  		// use in-reg args to keep them alive
   534  		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9] + a[10]
   535  	}
   536  	return n
   537  }
   538  
   539  //go:noinline
   540  func testTracebackArgs7c(a [10]int, b int) int {
   541  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   542  	if a[0] < 0 {
   543  		// use in-reg args to keep them alive
   544  		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9] + b
   545  	}
   546  	return n
   547  }
   548  
   549  //go:noinline
   550  func testTracebackArgs7d(a [11]int, b int) int {
   551  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   552  	if a[0] < 0 {
   553  		// use in-reg args to keep them alive
   554  		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9] + a[10] + b
   555  	}
   556  	return n
   557  }
   558  
   559  type testArgsType8a struct {
   560  	a, b, c, d, e, f, g, h int
   561  	i                      [2]int
   562  }
   563  type testArgsType8b struct {
   564  	a, b, c, d, e, f, g, h int
   565  	i                      [3]int
   566  }
   567  type testArgsType8c struct {
   568  	a, b, c, d, e, f, g, h int
   569  	i                      [2]int
   570  	j                      int
   571  }
   572  type testArgsType8d struct {
   573  	a, b, c, d, e, f, g, h int
   574  	i                      [3]int
   575  	j                      int
   576  }
   577  
   578  //go:noinline
   579  func testTracebackArgs8a(a testArgsType8a) int {
   580  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   581  	if a.a < 0 {
   582  		// use in-reg args to keep them alive
   583  		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1]
   584  	}
   585  	return n
   586  }
   587  
   588  //go:noinline
   589  func testTracebackArgs8b(a testArgsType8b) int {
   590  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   591  	if a.a < 0 {
   592  		// use in-reg args to keep them alive
   593  		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1] + a.i[2]
   594  	}
   595  	return n
   596  }
   597  
   598  //go:noinline
   599  func testTracebackArgs8c(a testArgsType8c) int {
   600  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   601  	if a.a < 0 {
   602  		// use in-reg args to keep them alive
   603  		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1] + a.j
   604  	}
   605  	return n
   606  }
   607  
   608  //go:noinline
   609  func testTracebackArgs8d(a testArgsType8d) int {
   610  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   611  	if a.a < 0 {
   612  		// use in-reg args to keep them alive
   613  		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1] + a.i[2] + a.j
   614  	}
   615  	return n
   616  }
   617  
   618  // nosplit to avoid preemption or morestack spilling registers.
   619  //
   620  //go:nosplit
   621  //go:noinline
   622  func testTracebackArgs9(a int64, b int32, c int16, d int8, x [2]int, y int) int {
   623  	if a < 0 {
   624  		println(&y) // take address, make y live, even if no longer used at traceback
   625  	}
   626  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   627  	if a < 0 {
   628  		// use half of in-reg args to keep them alive, the other half are dead
   629  		return int(a) + int(c)
   630  	}
   631  	return n
   632  }
   633  
   634  // nosplit to avoid preemption or morestack spilling registers.
   635  //
   636  //go:nosplit
   637  //go:noinline
   638  func testTracebackArgs10(a, b, c, d, e int32) int {
   639  	// no use of any args
   640  	return runtime.Stack(testTracebackArgsBuf[:], false)
   641  }
   642  
   643  // norace to avoid race instrumentation changing spill locations.
   644  // nosplit to avoid preemption or morestack spilling registers.
   645  //
   646  //go:norace
   647  //go:nosplit
   648  //go:noinline
   649  func testTracebackArgs11a(a, b, c int32) int {
   650  	if a < 0 {
   651  		println(a, b, c) // spill in a conditional, may not execute
   652  	}
   653  	if b < 0 {
   654  		return int(a + b + c)
   655  	}
   656  	return runtime.Stack(testTracebackArgsBuf[:], false)
   657  }
   658  
   659  // norace to avoid race instrumentation changing spill locations.
   660  // nosplit to avoid preemption or morestack spilling registers.
   661  //
   662  //go:norace
   663  //go:nosplit
   664  //go:noinline
   665  func testTracebackArgs11b(a, b, c, d int32) int {
   666  	var x int32
   667  	if a < 0 {
   668  		print() // spill b in a conditional
   669  		x = b
   670  	} else {
   671  		print() // spill c in a conditional
   672  		x = c
   673  	}
   674  	if d < 0 { // d is always needed
   675  		return int(x + d)
   676  	}
   677  	return runtime.Stack(testTracebackArgsBuf[:], false)
   678  }
   679  
   680  // norace to avoid race instrumentation changing spill locations.
   681  // nosplit to avoid preemption or morestack spilling registers.
   682  //
   683  //go:norace
   684  //go:nosplit
   685  //go:noinline
   686  func testTracebackArgsSlice(a []int) int {
   687  	n := runtime.Stack(testTracebackArgsBuf[:], false)
   688  	return a[1] + n
   689  }
   690  
   691  var testTracebackArgsSliceBackingStore [2]int
   692  
   693  // Poison the arg area with deterministic values.
   694  //
   695  //go:noinline
   696  func poisonStack() [20]int {
   697  	return [20]int{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}
   698  }
   699  
   700  func TestTracebackParentChildGoroutines(t *testing.T) {
   701  	parent := fmt.Sprintf("goroutine %d", runtime.Goid())
   702  	var wg sync.WaitGroup
   703  	wg.Add(1)
   704  	go func() {
   705  		defer wg.Done()
   706  		buf := make([]byte, 1<<10)
   707  		// We collect the stack only for this goroutine (by passing
   708  		// false to runtime.Stack). We expect to see the current
   709  		// goroutine ID, and the parent goroutine ID in a message like
   710  		// "created by ... in goroutine N".
   711  		stack := string(buf[:runtime.Stack(buf, false)])
   712  		child := fmt.Sprintf("goroutine %d", runtime.Goid())
   713  		if !strings.Contains(stack, parent) || !strings.Contains(stack, child) {
   714  			t.Errorf("did not see parent (%s) and child (%s) IDs in stack, got %s", parent, child, stack)
   715  		}
   716  	}()
   717  	wg.Wait()
   718  }
   719  
   720  type traceback struct {
   721  	frames    []*tbFrame
   722  	createdBy *tbFrame // no args
   723  }
   724  
   725  type tbFrame struct {
   726  	funcName string
   727  	args     string
   728  	inlined  bool
   729  
   730  	// elided is set to the number of frames elided, and the other fields are
   731  	// set to the zero value.
   732  	elided int
   733  
   734  	off int // byte offset in the traceback text of this frame
   735  }
   736  
   737  // parseTraceback parses a printed traceback to make it easier for tests to
   738  // check the result.
   739  func parseTraceback(t *testing.T, tb string) []*traceback {
   740  	//lines := strings.Split(tb, "\n")
   741  	//nLines := len(lines)
   742  	off := 0
   743  	lineNo := 0
   744  	fatal := func(f string, args ...any) {
   745  		msg := fmt.Sprintf(f, args...)
   746  		t.Fatalf("%s (line %d):\n%s", msg, lineNo, tb)
   747  	}
   748  	parseFrame := func(funcName, args string) *tbFrame {
   749  		// Consume file/line/etc
   750  		if !strings.HasPrefix(tb, "\t") {
   751  			fatal("missing source line")
   752  		}
   753  		_, tb, _ = strings.Cut(tb, "\n")
   754  		lineNo++
   755  		inlined := args == "..."
   756  		return &tbFrame{funcName: funcName, args: args, inlined: inlined, off: off}
   757  	}
   758  	var elidedRe = regexp.MustCompile(`^\.\.\.([0-9]+) frames elided\.\.\.$`)
   759  	var tbs []*traceback
   760  	var cur *traceback
   761  	tbLen := len(tb)
   762  	for len(tb) > 0 {
   763  		var line string
   764  		off = tbLen - len(tb)
   765  		line, tb, _ = strings.Cut(tb, "\n")
   766  		lineNo++
   767  		switch {
   768  		case strings.HasPrefix(line, "goroutine "):
   769  			cur = &traceback{}
   770  			tbs = append(tbs, cur)
   771  		case line == "":
   772  			// Separator between goroutines
   773  			cur = nil
   774  		case line[0] == '\t':
   775  			fatal("unexpected indent")
   776  		case strings.HasPrefix(line, "created by "):
   777  			funcName := line[len("created by "):]
   778  			cur.createdBy = parseFrame(funcName, "")
   779  		case strings.HasSuffix(line, ")"):
   780  			line = line[:len(line)-1] // Trim trailing ")"
   781  			funcName, args, found := strings.Cut(line, "(")
   782  			if !found {
   783  				fatal("missing (")
   784  			}
   785  			frame := parseFrame(funcName, args)
   786  			cur.frames = append(cur.frames, frame)
   787  		case elidedRe.MatchString(line):
   788  			// "...N frames elided..."
   789  			nStr := elidedRe.FindStringSubmatch(line)
   790  			n, _ := strconv.Atoi(nStr[1])
   791  			frame := &tbFrame{elided: n}
   792  			cur.frames = append(cur.frames, frame)
   793  		}
   794  	}
   795  	return tbs
   796  }
   797  
   798  // parseTraceback1 is like parseTraceback, but expects tb to contain exactly one
   799  // goroutine.
   800  func parseTraceback1(t *testing.T, tb string) *traceback {
   801  	tbs := parseTraceback(t, tb)
   802  	if len(tbs) != 1 {
   803  		t.Fatalf("want 1 goroutine, got %d:\n%s", len(tbs), tb)
   804  	}
   805  	return tbs[0]
   806  }
   807  
   808  //go:noinline
   809  func testTracebackGenericFn[T any](buf []byte) int {
   810  	return runtime.Stack(buf[:], false)
   811  }
   812  
   813  func testTracebackGenericFnInlined[T any](buf []byte) int {
   814  	return runtime.Stack(buf[:], false)
   815  }
   816  
   817  type testTracebackGenericTyp[P any] struct{ x P }
   818  
   819  //go:noinline
   820  func (t testTracebackGenericTyp[P]) M(buf []byte) int {
   821  	return runtime.Stack(buf[:], false)
   822  }
   823  
   824  func (t testTracebackGenericTyp[P]) Inlined(buf []byte) int {
   825  	return runtime.Stack(buf[:], false)
   826  }
   827  
   828  func TestTracebackGeneric(t *testing.T) {
   829  	if *flagQuick {
   830  		t.Skip("-quick")
   831  	}
   832  	var x testTracebackGenericTyp[int]
   833  	tests := []struct {
   834  		fn     func([]byte) int
   835  		expect string
   836  	}{
   837  		// function, not inlined
   838  		{
   839  			testTracebackGenericFn[int],
   840  			"testTracebackGenericFn[...](",
   841  		},
   842  		// function, inlined
   843  		{
   844  			func(buf []byte) int { return testTracebackGenericFnInlined[int](buf) },
   845  			"testTracebackGenericFnInlined[...](",
   846  		},
   847  		// method, not inlined
   848  		{
   849  			x.M,
   850  			"testTracebackGenericTyp[...].M(",
   851  		},
   852  		// method, inlined
   853  		{
   854  			func(buf []byte) int { return x.Inlined(buf) },
   855  			"testTracebackGenericTyp[...].Inlined(",
   856  		},
   857  	}
   858  	var buf [1000]byte
   859  	for _, test := range tests {
   860  		n := test.fn(buf[:])
   861  		got := buf[:n]
   862  		if !bytes.Contains(got, []byte(test.expect)) {
   863  			t.Errorf("traceback does not contain expected string: want %q, got\n%s", test.expect, got)
   864  		}
   865  		if bytes.Contains(got, []byte("shape")) { // should not contain shape name
   866  			t.Errorf("traceback contains shape name: got\n%s", got)
   867  		}
   868  	}
   869  }
   870
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