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

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