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cmd: vendor golang.org/x/tools/cmd/bisect

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Vendoring for use with the internal/godebug test
and eventually the cmd/compile test as well.

Change-Id: I3f7151949cff584705cb32ba39bf5de5cd45c3f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/493597
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Russ Cox 2023-05-08 13:39:27 -04:00
parent e5e61a03d9
commit 8d5065ce6e
7 changed files with 1184 additions and 0 deletions
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src/cmd/tools/tools.go Normal file
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// Copyright 2023 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.
//go:build tools
package tools
// Arrange to vendor the bisect command for use
// by the internal/godebug package test.
import _ "golang.org/x/tools/cmd/bisect"

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src/cmd/vendor/golang.org/x/tools/cmd/bisect/go119.go generated vendored Normal file
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// Copyright 2023 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.
//go:build !go1.20
package main
import "os/exec"
func cmdInterrupt(cmd *exec.Cmd) {
// cmd.Cancel and cmd.WaitDelay not available before Go 1.20.
}

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src/cmd/vendor/golang.org/x/tools/cmd/bisect/go120.go generated vendored Normal file
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// Copyright 2023 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.
//go:build go1.20
package main
import (
"os"
"os/exec"
"time"
)
func cmdInterrupt(cmd *exec.Cmd) {
cmd.Cancel = func() error {
// On timeout, send interrupt,
// in hopes of shutting down process tree.
// Ignore errors sending signal; it's all best effort
// and not even implemented on Windows.
// TODO(rsc): Maybe use a new process group and kill the whole group?
cmd.Process.Signal(os.Interrupt)
return nil
}
cmd.WaitDelay = 2 * time.Second
}

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src/cmd/vendor/golang.org/x/tools/cmd/bisect/main.go generated vendored Normal file
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// Copyright 2023 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.
// Bisect finds changes responsible for causing a failure.
// A typical use is to identify the source locations in a program
// that are miscompiled by a given compiler optimization.
//
// Usage:
//
// bisect [flags] [var=value...] command [arguments...]
//
// Bisect operates on a target command line – the target – that can be
// run with various changes individually enabled or disabled. With none
// of the changes enabled, the target is known to succeed (exit with exit
// code zero). With all the changes enabled, the target is known to fail
// (exit any other way). Bisect repeats the target with different sets of
// changes enabled, using binary search to find (non-overlapping) minimal
// change sets that preserve the failure.
//
// The target must cooperate with bisect by accepting a change pattern
// and then enabling and reporting the changes that match that pattern.
// The change pattern is passed to the target by substituting it anywhere
// the string PATTERN appears in the environment values or the command
// arguments. For each change that matches the pattern, the target must
// enable that change and also print one or more “match lines”
// (to standard output or standard error) describing the change.
// The [golang.org/x/tools/internal/bisect] package provides functions to help
// targets implement this protocol. We plan to publish that package
// in a non-internal location after finalizing its API.
//
// # Command Line Flags
//
// Bisect supports the following command-line flags:
//
// -max M
//
// Stop after finding M minimal change sets. The default is no maximum, meaning to run until
// all changes that provoke a failure have been identified.
//
// -maxset S
//
// Disallow change sets larger than S elements. The default is no maximum.
//
// -timeout D
//
// If the target runs for longer than duration D, stop the target and interpret that as a failure.
// The default is no timeout.
//
// -count N
//
// Run each trial N times (default 2), checking for consistency.
//
// -v
//
// Print verbose output, showing each run and its match lines.
//
// # Example
//
// For example, the Go compiler can be used as a bisect target to
// determine the source locations that cause a test failure when compiled with
// a new optimization:
//
// bisect go test -gcflags=all=-d=loopvarhash=PATTERN
//
// The -gcflags=all= instructs the go command to pass the -d=... to the Go compiler
// when compiling all packages. Bisect replaces the literal text “PATTERN” with a specific pattern
// on each invocation, varying the patterns to determine the minimal set of changes
// needed to reproduce the failure.
//
// # Defeating Build Caches
//
// Build systems cache build results, to avoid repeating the same compilations
// over and over. When using a cached build result, the go command (correctly)
// reprints the cached standard output and standard error associated with that
// command invocation. (This makes commands like 'go build -gcflags=-S' for
// printing an assembly listing work reliably.)
//
// Unfortunately, most build systems, including Bazel, are not as careful
// as the go command about reprinting compiler output. If the compiler is
// what prints match lines, a build system that suppresses compiler
// output when using cached compiler results will confuse bisect.
// To defeat such build caches, bisect replaces the literal text “RANDOM”
// in environment values and command arguments with a random 64-bit value
// during each invocation. The Go compiler conveniently accepts a
// -d=ignore=... debug flag that ignores its argument, so to run the
// previous example using Bazel, the invocation is:
//
// bazel test --define=gc_goopts=-d=loopvarhash=PATTERN,unused=RANDOM //path/to:test
package main
import (
"context"
"flag"
"fmt"
"io"
"log"
"math/rand"
"os"
"os/exec"
"strconv"
"strings"
"time"
"golang.org/x/tools/internal/bisect"
)
// Preserve import of bisect, to allow [bisect.Match] in the doc comment.
var _ bisect.Matcher
func usage() {
fmt.Fprintf(os.Stderr, "usage: bisect [flags] [var=value...] command [arguments...]\n")
flag.PrintDefaults()
os.Exit(2)
}
func main() {
log.SetFlags(0)
log.SetPrefix("bisect: ")
var b Bisect
b.Stdout = os.Stdout
b.Stderr = os.Stderr
flag.IntVar(&b.Max, "max", 0, "stop after finding `m` failing change sets")
flag.IntVar(&b.MaxSet, "maxset", 0, "do not search for change sets larger than `s` elements")
flag.DurationVar(&b.Timeout, "timeout", 0, "stop target and consider failed after duration `d`")
flag.IntVar(&b.Count, "count", 2, "run target `n` times for each trial")
flag.BoolVar(&b.Verbose, "v", false, "enable verbose output")
flag.Usage = usage
flag.Parse()
args := flag.Args()
// Split command line into env settings, command name, args.
i := 0
for i < len(args) && strings.Contains(args[i], "=") {
i++
}
if i == len(args) {
usage()
}
b.Env, b.Cmd, b.Args = args[:i], args[i], args[i+1:]
if !b.Search() {
os.Exit(1)
}
}
// A Bisect holds the state for a bisect invocation.
type Bisect struct {
// Env is the additional environment variables for the command.
// PATTERN and RANDOM are substituted in the values, but not the names.
Env []string
// Cmd is the command (program name) to run.
// PATTERN and RANDOM are not substituted.
Cmd string
// Args is the command arguments.
// PATTERN and RANDOM are substituted anywhere they appear.
Args []string
// Command-line flags controlling bisect behavior.
Max int // maximum number of sets to report (0 = unlimited)
MaxSet int // maximum number of elements in a set (0 = unlimited)
Timeout time.Duration // kill target and assume failed after this duration (0 = unlimited)
Count int // run target this many times for each trial and give up if flaky (min 1 assumed; default 2 on command line set in main)
Verbose bool // print long output about each trial (only useful for debugging bisect itself)
// State for running bisect, replaced during testing.
// Failing change sets are printed to Stdout; all other output goes to Stderr.
Stdout io.Writer // where to write standard output (usually os.Stdout)
Stderr io.Writer // where to write standard error (usually os.Stderr)
TestRun func(env []string, cmd string, args []string) (out []byte, err error) // if non-nil, used instead of exec.Command
// State maintained by Search.
// By default, Search looks for a minimal set of changes that cause a failure when enabled.
// If Disable is true, the search is inverted and seeks a minimal set of changes that
// cause a failure when disabled. In this case, the search proceeds as normal except that
// each pattern starts with a !.
Disable bool
// Add is a list of suffixes to add to every trial, because they
// contain changes that are necessary for a group we are assembling.
Add []string
// Skip is a list of suffixes that uniquely identify changes to exclude from every trial,
// because they have already been used in failing change sets.
// Suffixes later in the list may only be unique after removing
// the ones earlier in the list.
// Skip applies after Add.
Skip []string
}
// A Result holds the result of a single target trial.
type Result struct {
Success bool // whether the target succeeded (exited with zero status)
Cmd string // full target command line
Out string // full target output (stdout and stderr combined)
Suffix string // the suffix used for collecting MatchIDs, MatchText, and MatchFull
MatchIDs []uint64 // match IDs enabled during this trial
MatchText []string // match reports for the IDs, with match markers removed
MatchFull []string // full match lines for the IDs, with match markers kept
}
// &searchFatal is a special panic value to signal that Search failed.
// This lets us unwind the search recursion on a fatal error
// but have Search return normally.
var searchFatal int
// Search runs a bisect search according to the configuration in b.
// It reports whether any failing change sets were found.
func (b *Bisect) Search() bool {
defer func() {
// Recover from panic(&searchFatal), implicitly returning false from Search.
// Re-panic on any other panic.
if e := recover(); e != nil && e != &searchFatal {
panic(e)
}
}()
// Run with no changes and all changes, to figure out which direction we're searching.
// The goal is to find the minimal set of changes to toggle
// starting with the state where everything works.
// If "no changes" succeeds and "all changes" fails,
// we're looking for a minimal set of changes to enable to provoke the failure
// (broken = runY, b.Negate = false)
// If "no changes" fails and "all changes" succeeds,
// we're looking for a minimal set of changes to disable to provoke the failure
// (broken = runN, b.Negate = true).
b.Logf("checking target with all changes disabled")
runN := b.Run("n")
b.Logf("checking target with all changes enabled")
runY := b.Run("y")
var broken *Result
switch {
case runN.Success && !runY.Success:
b.Logf("target succeeds with no changes, fails with all changes")
b.Logf("searching for minimal set of enabled changes causing failure")
broken = runY
b.Disable = false
case !runN.Success && runY.Success:
b.Logf("target fails with no changes, succeeds with all changes")
b.Logf("searching for minimal set of disabled changes causing failure")
broken = runN
b.Disable = true
case runN.Success && runY.Success:
b.Fatalf("target succeeds with no changes and all changes")
case !runN.Success && !runY.Success:
b.Fatalf("target fails with no changes and all changes")
}
// Loop finding and printing change sets, until none remain.
found := 0
for {
// Find set.
bad := b.search(broken)
if bad == nil {
if found == 0 {
b.Fatalf("cannot find any failing change sets of size ≤ %d", b.MaxSet)
}
break
}
// Confirm that set really does fail, to avoid false accusations.
// Also asking for user-visible output; earlier runs did not.
b.Logf("confirming failing change set")
b.Add = append(b.Add[:0], bad...)
broken = b.Run("v")
if broken.Success {
b.Logf("confirmation run succeeded unexpectedly")
}
b.Add = b.Add[:0]
// Print confirmed change set.
found++
b.Logf("FOUND failing change set")
desc := "(enabling changes causes failure)"
if b.Disable {
desc = "(disabling changes causes failure)"
}
fmt.Fprintf(b.Stdout, "--- change set #%d %s\n%s\n---\n", found, desc, strings.Join(broken.MatchText, "\n"))
// Stop if we've found enough change sets.
if b.Max > 0 && found >= b.Max {
break
}
// If running bisect target | tee bad.txt, prints to stdout and stderr
// both appear on the terminal, but the ones to stdout go through tee
// and can take a little bit of extra time. Sleep 1 millisecond to give
// tee time to catch up, so that its stdout print does not get interlaced
// with the stderr print from the next b.Log message.
time.Sleep(1 * time.Millisecond)
// Disable the now-known-bad changes and see if any failures remain.
b.Logf("checking for more failures")
b.Skip = append(bad, b.Skip...)
broken = b.Run("")
if broken.Success {
what := "enabled"
if b.Disable {
what = "disabled"
}
b.Logf("target succeeds with all remaining changes %s", what)
break
}
b.Logf("target still fails; searching for more bad changes")
}
return true
}
// Fatalf prints a message to standard error and then panics,
// causing Search to return false.
func (b *Bisect) Fatalf(format string, args ...any) {
s := fmt.Sprintf("bisect: fatal error: "+format, args...)
if !strings.HasSuffix(s, "\n") {
s += "\n"
}
b.Stderr.Write([]byte(s))
panic(&searchFatal)
}
// Logf prints a message to standard error.
func (b *Bisect) Logf(format string, args ...any) {
s := fmt.Sprintf("bisect: "+format, args...)
if !strings.HasSuffix(s, "\n") {
s += "\n"
}
b.Stderr.Write([]byte(s))
}
// search searches for a single locally minimal change set.
//
// Invariant: r describes the result of r.Suffix + b.Add, which failed.
// (There's an implicit -b.Skip everywhere here. b.Skip does not change.)
// We want to extend r.Suffix to preserve the failure, working toward
// a suffix that identifies a single change.
func (b *Bisect) search(r *Result) []string {
// The caller should be passing in a failure result that we diagnose.
if r.Success {
b.Fatalf("internal error: unexpected success") // mistake by caller
}
// If the failure reported no changes, the target is misbehaving.
if len(r.MatchIDs) == 0 {
b.Fatalf("failure with no reported changes:\n\n$ %s\n%s\n", r.Cmd, r.Out)
}
// If there's one matching change, that's the one we're looking for.
if len(r.MatchIDs) == 1 {
if r.Suffix == "" {
return []string{"y"}
}
return []string{r.Suffix}
}
// If the suffix we were tracking in the trial is already 64 bits,
// either the target is bad or bisect itself is buggy.
if len(r.Suffix) >= 64 {
b.Fatalf("failed to isolate a single change with very long suffix")
}
// We want to split the current matchIDs by left-extending the suffix with 0 and 1.
// If all the matches have the same next bit, that won't cause a split, which doesn't
// break the algorithm but does waste time. Avoid wasting time by left-extending
// the suffix to the longest suffix shared by all the current match IDs
// before adding 0 or 1.
suffix := commonSuffix(r.MatchIDs)
if !strings.HasSuffix(suffix, r.Suffix) {
b.Fatalf("internal error: invalid common suffix") // bug in commonSuffix
}
// Run 0suffix and 1suffix. If one fails, chase down the failure in that half.
r0 := b.Run("0" + suffix)
if !r0.Success {
return b.search(r0)
}
r1 := b.Run("1" + suffix)
if !r1.Success {
return b.search(r1)
}
// suffix failed, but 0suffix and 1suffix succeeded.
// Assuming the target isn't flaky, this means we need
// at least one change from 0suffix AND at least one from 1suffix.
// We are already tracking N = len(b.Add) other changes and are
// allowed to build sets of size at least 1+N (or we shouldn't be here at all).
// If we aren't allowed to build sets of size 2+N, give up this branch.
if b.MaxSet > 0 && 2+len(b.Add) > b.MaxSet {
return nil
}
// Adding all matches for 1suffix, recurse to narrow down 0suffix.
old := len(b.Add)
b.Add = append(b.Add, "1"+suffix)
r0 = b.Run("0" + suffix)
if r0.Success {
// 0suffix + b.Add + 1suffix = suffix + b.Add is what r describes, and it failed.
b.Fatalf("target fails inconsistently")
}
bad0 := b.search(r0)
if bad0 == nil {
// Search failed due to MaxSet limit.
return nil
}
b.Add = b.Add[:old]
// Adding the specific match we found in 0suffix, recurse to narrow down 1suffix.
b.Add = append(b.Add[:old], bad0...)
r1 = b.Run("1" + suffix)
if r1.Success {
// 1suffix + b.Add + bad0 = bad0 + b.Add + 1suffix is what b.search(r0) reported as a failure.
b.Fatalf("target fails inconsistently")
}
bad1 := b.search(r1)
if bad1 == nil {
// Search failed due to MaxSet limit.
return nil
}
b.Add = b.Add[:old]
// bad0 and bad1 together provoke the failure.
return append(bad0, bad1...)
}
// Run runs a set of trials selecting changes with the given suffix,
// plus the ones in b.Add and not the ones in b.Skip.
// The returned result's MatchIDs, MatchText, and MatchFull
// only list the changes that match suffix.
// When b.Count > 1, Run runs b.Count trials and requires
// that they all succeed or they all fail. If not, it calls b.Fatalf.
func (b *Bisect) Run(suffix string) *Result {
out := b.run(suffix)
for i := 1; i < b.Count; i++ {
r := b.run(suffix)
if r.Success != out.Success {
b.Fatalf("target fails inconsistently")
}
}
return out
}
// run runs a single trial for Run.
func (b *Bisect) run(suffix string) *Result {
random := fmt.Sprint(rand.Uint64())
// Accept suffix == "v" to mean we need user-visible output.
visible := ""
if suffix == "v" {
visible = "v"
suffix = ""
}
// Construct change ID pattern.
var pattern string
if suffix == "y" || suffix == "n" {
pattern = suffix
suffix = ""
} else {
var elem []string
if suffix != "" {
elem = append(elem, "+", suffix)
}
for _, x := range b.Add {
elem = append(elem, "+", x)
}
for _, x := range b.Skip {
elem = append(elem, "-", x)
}
pattern = strings.Join(elem, "")
if pattern == "" {
pattern = "y"
}
}
if b.Disable {
pattern = "!" + pattern
}
pattern = visible + pattern
// Construct substituted env and args.
env := make([]string, len(b.Env))
for i, x := range b.Env {
k, v, _ := strings.Cut(x, "=")
env[i] = k + "=" + replace(v, pattern, random)
}
args := make([]string, len(b.Args))
for i, x := range b.Args {
args[i] = replace(x, pattern, random)
}
// Construct and log command line.
// There is no newline in the log print.
// The line will be completed when the command finishes.
cmdText := strings.Join(append(append(env, b.Cmd), args...), " ")
fmt.Fprintf(b.Stderr, "bisect: run: %s...", cmdText)
// Run command with args and env.
var out []byte
var err error
if b.TestRun != nil {
out, err = b.TestRun(env, b.Cmd, args)
} else {
ctx := context.Background()
if b.Timeout != 0 {
var cancel context.CancelFunc
ctx, cancel = context.WithTimeout(ctx, b.Timeout)
defer cancel()
}
cmd := exec.CommandContext(ctx, b.Cmd, args...)
cmd.Env = append(os.Environ(), env...)
// Set up cmd.Cancel, cmd.WaitDelay on Go 1.20 and later
// TODO(rsc): Inline go120.go's cmdInterrupt once we stop supporting Go 1.19.
cmdInterrupt(cmd)
out, err = cmd.CombinedOutput()
}
// Parse output to construct result.
r := &Result{
Suffix: suffix,
Success: err == nil,
Cmd: cmdText,
Out: string(out),
}
// Calculate bits, mask to identify suffix matches.
var bits, mask uint64
if suffix != "" && suffix != "y" && suffix != "n" && suffix != "v" {
var err error
bits, err = strconv.ParseUint(suffix, 2, 64)
if err != nil {
b.Fatalf("internal error: bad suffix")
}
mask = uint64(1<<len(suffix)) - 1
}
// Process output, collecting match reports for suffix.
have := make(map[uint64]bool)
all := r.Out
for all != "" {
var line string
line, all, _ = strings.Cut(all, "\n")
short, id, ok := bisect.CutMarker(line)
if !ok || (id&mask) != bits {
continue
}
if !have[id] {
have[id] = true
r.MatchIDs = append(r.MatchIDs, id)
}
r.MatchText = append(r.MatchText, short)
r.MatchFull = append(r.MatchFull, line)
}
// Finish log print from above, describing the command's completion.
if err == nil {
fmt.Fprintf(b.Stderr, " ok (%d matches)\n", len(r.MatchIDs))
} else {
fmt.Fprintf(b.Stderr, " FAIL (%d matches)\n", len(r.MatchIDs))
}
if err != nil && len(r.MatchIDs) == 0 {
b.Fatalf("target failed without printing any matches\n%s", r.Out)
}
// In verbose mode, print extra debugging: all the lines with match markers.
if b.Verbose {
b.Logf("matches:\n%s", strings.Join(r.MatchFull, "\n\t"))
}
return r
}
// replace returns x with literal text PATTERN and RANDOM replaced by pattern and random.
func replace(x, pattern, random string) string {
x = strings.ReplaceAll(x, "PATTERN", pattern)
x = strings.ReplaceAll(x, "RANDOM", random)
return x
}
// commonSuffix returns the longest common binary suffix shared by all uint64s in list.
// If list is empty, commonSuffix returns an empty string.
func commonSuffix(list []uint64) string {
if len(list) == 0 {
return ""
}
b := list[0]
n := 64
for _, x := range list {
for x&((1<<n)-1) != b {
n--
b &= (1 << n) - 1
}
}
s := make([]byte, n)
for i := n - 1; i >= 0; i-- {
s[i] = '0' + byte(b&1)
b >>= 1
}
return string(s[:])
}

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// Copyright 2023 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.
// Starting in Go 1.20, the global rand is auto-seeded,
// with a better value than the current Unix nanoseconds.
// Only seed if we're using older versions of Go.
//go:build !go1.20
package main
import (
"math/rand"
"time"
)
func init() {
rand.Seed(time.Now().UnixNano())
}

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// Copyright 2023 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 bisect can be used by compilers and other programs
// to serve as a target for the bisect debugging tool.
// See [golang.org/x/tools/cmd/bisect] for details about using the tool.
//
// To be a bisect target, allowing bisect to help determine which of a set of independent
// changes provokes a failure, a program needs to:
//
// 1. Define a way to accept a change pattern on its command line or in its environment.
// The most common mechanism is a command-line flag.
// The pattern can be passed to [New] to create a [Matcher], the compiled form of a pattern.
//
// 2. Assign each change a unique ID. One possibility is to use a sequence number,
// but the most common mechanism is to hash some kind of identifying information
// like the file and line number where the change might be applied.
// [Hash] hashes its arguments to compute an ID.
//
// 3. Enable each change that the pattern says should be enabled.
// The [Matcher.Enable] method answers this question for a given change ID.
//
// 4. Report each change that the pattern says should be reported.
// The [Matcher.Report] method answers this question for a given change ID.
// The report consists of one more lines on standard error or standard output
// that contain a “match marker”. [Marker] returns the match marker for a given ID.
// When bisect reports a change as causing the failure, it identifies the change
// by printing those report lines, with the match marker removed.
//
// # Example Usage
//
// A program starts by defining how it receives the pattern. In this example, we will assume a flag.
// The next step is to compile the pattern:
//
// m, err := bisect.New(patternFlag)
// if err != nil {
// log.Fatal(err)
// }
//
// Then, each time a potential change is considered, the program computes
// a change ID by hashing identifying information (source file and line, in this case)
// and then calls m.ShouldEnable and m.ShouldReport to decide whether to
// enable and report the change, respectively:
//
// for each change {
// h := bisect.Hash(file, line)
// if m.ShouldEnable(h) {
// enableChange()
// }
// if m.ShouldReport(h) {
// log.Printf("%v %s:%d", bisect.Marker(h), file, line)
// }
// }
//
// Note that the two return different values when bisect is searching for a
// minimal set of changes to disable to provoke a failure.
//
// Finally, note that New returns a nil Matcher when there is no pattern,
// meaning that the target is not running under bisect at all.
// In that common case, the computation of the hash can be avoided entirely
// by checking for m == nil first:
//
// for each change {
// if m == nil {
// enableChange()
// } else {
// h := bisect.Hash(file, line)
// if m.ShouldEnable(h) {
// enableChange()
// }
// if m.ShouldReport(h) {
// log.Printf("%v %s:%d", bisect.Marker(h), file, line)
// }
// }
// }
//
// # Pattern Syntax
//
// Patterns are generated by the bisect tool and interpreted by [New].
// Users should not have to understand the patterns except when
// debugging a target's bisect support or debugging the bisect tool itself.
//
// The pattern syntax selecting a change is a sequence of bit strings
// separated by + and - operators. Each bit string denotes the set of
// changes with IDs ending in those bits, + is set addition, - is set subtraction,
// and the expression is evaluated in the usual left-to-right order.
// The special binary number “y” denotes the set of all changes,
// standing in for the empty bit string.
// In the expression, all the + operators must appear before all the - operators.
// A leading + adds to an empty set. A leading - subtracts from the set of all
// possible suffixes.
//
// For example:
//
// - “01+10” and “+01+10” both denote the set of changes
// with IDs ending with the bits 01 or 10.
//
// - “01+10-1001” denotes the set of changes with IDs
// ending with the bits 01 or 10, but excluding those ending in 1001.
//
// - “-01-1000” and “y-01-1000 both denote the set of all changes
// with IDs not ending in 01 nor 1000.
//
// - “0+1-01+001” is not a valid pattern, because all the + operators do not
// appear before all the - operators.
//
// In the syntaxes described so far, the pattern specifies the changes to
// enable and report. If a pattern is prefixed by a “!”, the meaning
// changes: the pattern specifies the changes to DISABLE and report. This
// mode of operation is needed when a program passes with all changes
// enabled but fails with no changes enabled. In this case, bisect
// searches for minimal sets of changes to disable.
// Put another way, the leading “!” inverts the result from [Matcher.ShouldEnable]
// but does not invert the result from [Matcher.ShouldReport].
//
// As a convenience for manual debugging, “n” is an alias for “!y”,
// meaning to disable and report all changes.
//
// Finally, a leading “v” in the pattern indicates that the reports will be shown
// to the user of bisect to describe the changes involved in a failure.
// At the API level, the leading “v” causes [Matcher.Visible] to return true.
// See the next section for details.
//
// # Match Reports
//
// The target program must enable only those changed matched
// by the pattern, and it must print a match report for each such change.
// A match report consists of one or more lines of text that will be
// printed by the bisect tool to describe a change implicated in causing
// a failure. Each line in the report for a given change must contain a
// match marker with that change ID, as returned by [Marker].
// The markers are elided when displaying the lines to the user.
//
// A match marker has the form “[bisect-match 0x1234]” where
// 0x1234 is the change ID in hexadecimal.
// An alternate form is “[bisect-match 010101]”, giving the change ID in binary.
//
// When [Matcher.Visible] returns false, the match reports are only
// being processed by bisect to learn the set of enabled changes,
// not shown to the user, meaning that each report can be a match
// marker on a line by itself, eliding the usual textual description.
// When the textual description is expensive to compute,
// checking [Matcher.Visible] can help the avoid that expense
// in most runs.
package bisect
// New creates and returns a new Matcher implementing the given pattern.
// The pattern syntax is defined in the package doc comment.
//
// In addition to the pattern syntax syntax, New("") returns nil, nil.
// The nil *Matcher is valid for use: it returns true from ShouldEnable
// and false from ShouldReport for all changes. Callers can avoid calling
// [Hash], [Matcher.ShouldEnable], and [Matcher.ShouldPrint] entirely
// when they recognize the nil Matcher.
func New(pattern string) (*Matcher, error) {
if pattern == "" {
return nil, nil
}
m := new(Matcher)
// Allow multiple v, so that “bisect cmd vPATTERN” can force verbose all the time.
p := pattern
for len(p) > 0 && p[0] == 'v' {
m.verbose = true
p = p[1:]
if p == "" {
return nil, &parseError{"invalid pattern syntax: " + pattern}
}
}
// Allow multiple !, each negating the last, so that “bisect cmd !PATTERN” works
// even when bisect chooses to add its own !.
m.enable = true
for len(p) > 0 && p[0] == '!' {
m.enable = !m.enable
p = p[1:]
if p == "" {
return nil, &parseError{"invalid pattern syntax: " + pattern}
}
}
if p == "n" {
// n is an alias for !y.
m.enable = !m.enable
p = "y"
}
// Parse actual pattern syntax.
result := true
bits := uint64(0)
start := 0
for i := 0; i <= len(p); i++ {
// Imagine a trailing - at the end of the pattern to flush final suffix
c := byte('-')
if i < len(p) {
c = p[i]
}
switch c {
default:
return nil, &parseError{"invalid pattern syntax: " + pattern}
case '0', '1':
bits = bits<<1 | uint64(c-'0')
case 'y':
if i+1 < len(p) && (p[i+1] == '0' || p[i+1] == '1') {
return nil, &parseError{"invalid pattern syntax: " + pattern}
}
bits = 0
case '+', '-':
if c == '+' && result == false {
// Have already seen a -. Should be - from here on.
return nil, &parseError{"invalid pattern syntax (+ after -): " + pattern}
}
if i > 0 {
n := i - start
if n > 64 {
return nil, &parseError{"pattern bits too long: " + pattern}
}
if n <= 0 {
return nil, &parseError{"invalid pattern syntax: " + pattern}
}
if p[start] == 'y' {
n = 0
}
mask := uint64(1)<<n - 1
m.list = append(m.list, cond{mask, bits, result})
} else if c == '-' {
// leading - subtracts from complete set
m.list = append(m.list, cond{0, 0, true})
}
bits = 0
result = c == '+'
start = i + 1
}
}
return m, nil
}
// A Matcher is the parsed, compiled form of a PATTERN string.
// The nil *Matcher is valid: it has all changes enabled but none reported.
type Matcher struct {
verbose bool
enable bool // when true, list is for “enable and report” (when false, “disable and report”)
list []cond // conditions; later ones win over earlier ones
}
// A cond is a single condition in the matcher.
// Given an input id, if id&mask == bits, return the result.
type cond struct {
mask uint64
bits uint64
result bool
}
// Verbose reports whether the reports will be shown to users
// and need to include a human-readable change description.
// If not, the target can print just the Marker on a line by itself
// and perhaps save some computation.
func (m *Matcher) Verbose() bool {
return m.verbose
}
// ShouldEnable reports whether the change with the given id should be enabled.
func (m *Matcher) ShouldEnable(id uint64) bool {
if m == nil {
return true
}
for i := len(m.list) - 1; i >= 0; i-- {
c := &m.list[i]
if id&c.mask == c.bits {
return c.result == m.enable
}
}
return false == m.enable
}
// ShouldReport reports whether the change with the given id should be reported.
func (m *Matcher) ShouldReport(id uint64) bool {
if m == nil {
return false
}
for i := len(m.list) - 1; i >= 0; i-- {
c := &m.list[i]
if id&c.mask == c.bits {
return c.result
}
}
return false
}
// Marker returns the match marker text to use on any line reporting details
// about a match of the given ID.
// It always returns the hexadecimal format.
func Marker(id uint64) string {
return string(AppendMarker(nil, id))
}
// AppendMarker is like [Marker] but appends the marker to dst.
func AppendMarker(dst []byte, id uint64) []byte {
const prefix = "[bisect-match 0x"
var buf [len(prefix) + 16 + 1]byte
copy(buf[:], prefix)
for i := 0; i < 16; i++ {
buf[len(prefix)+i] = "0123456789abcdef"[id>>60]
id <<= 4
}
buf[len(prefix)+16] = ']'
return append(dst, buf[:]...)
}
// CutMarker finds the first match marker in line and removes it,
// returning the shortened line (with the marker removed),
// the ID from the match marker,
// and whether a marker was found at all.
// If there is no marker, CutMarker returns line, 0, false.
func CutMarker(line string) (short string, id uint64, ok bool) {
// Find first instance of prefix.
prefix := "[bisect-match "
i := 0
for ; ; i++ {
if i >= len(line)-len(prefix) {
return line, 0, false
}
if line[i] == '[' && line[i:i+len(prefix)] == prefix {
break
}
}
// Scan to ].
j := i + len(prefix)
for j < len(line) && line[j] != ']' {
j++
}
if j >= len(line) {
return line, 0, false
}
// Parse id.
idstr := line[i+len(prefix) : j]
if len(idstr) >= 3 && idstr[:2] == "0x" {
// parse hex
if len(idstr) > 2+16 { // max 0x + 16 digits
return line, 0, false
}
for i := 2; i < len(idstr); i++ {
id <<= 4
switch c := idstr[i]; {
case '0' <= c && c <= '9':
id |= uint64(c - '0')
case 'a' <= c && c <= 'f':
id |= uint64(c - 'a' + 10)
case 'A' <= c && c <= 'F':
id |= uint64(c - 'A' + 10)
}
}
} else {
if idstr == "" || len(idstr) > 64 { // min 1 digit, max 64 digits
return line, 0, false
}
// parse binary
for i := 0; i < len(idstr); i++ {
id <<= 1
switch c := idstr[i]; c {
default:
return line, 0, false
case '0', '1':
id |= uint64(c - '0')
}
}
}
// Construct shortened line.
// Remove at most one space from around the marker,
// so that "foo [marker] bar" shortens to "foo bar".
j++ // skip ]
if i > 0 && line[i-1] == ' ' {
i--
} else if j < len(line) && line[j] == ' ' {
j++
}
short = line[:i] + line[j:]
return short, id, true
}
// Hash computes a hash of the data arguments,
// each of which must be of type string, byte, int, uint, int32, uint32, int64, uint64, uintptr, or a slice of one of those types.
func Hash(data ...any) uint64 {
h := offset64
for _, v := range data {
switch v := v.(type) {
default:
// Note: Not printing the type, because reflect.ValueOf(v)
// would make the interfaces prepared by the caller escape
// and therefore allocate. This way, Hash(file, line) runs
// without any allocation. It should be clear from the
// source code calling Hash what the bad argument was.
panic("bisect.Hash: unexpected argument type")
case string:
h = fnvString(h, v)
case byte:
h = fnv(h, v)
case int:
h = fnvUint64(h, uint64(v))
case uint:
h = fnvUint64(h, uint64(v))
case int32:
h = fnvUint32(h, uint32(v))
case uint32:
h = fnvUint32(h, v)
case int64:
h = fnvUint64(h, uint64(v))
case uint64:
h = fnvUint64(h, v)
case uintptr:
h = fnvUint64(h, uint64(v))
case []string:
for _, x := range v {
h = fnvString(h, x)
}
case []byte:
for _, x := range v {
h = fnv(h, x)
}
case []int:
for _, x := range v {
h = fnvUint64(h, uint64(x))
}
case []uint:
for _, x := range v {
h = fnvUint64(h, uint64(x))
}
case []int32:
for _, x := range v {
h = fnvUint32(h, uint32(x))
}
case []uint32:
for _, x := range v {
h = fnvUint32(h, x)
}
case []int64:
for _, x := range v {
h = fnvUint64(h, uint64(x))
}
case []uint64:
for _, x := range v {
h = fnvUint64(h, x)
}
case []uintptr:
for _, x := range v {
h = fnvUint64(h, uint64(x))
}
}
}
return h
}
// Trivial error implementation, here to avoid importing errors.
type parseError struct{ text string }
func (e *parseError) Error() string { return e.text }
// FNV-1a implementation. See Go's hash/fnv/fnv.go.
// Copied here for simplicity (can handle uints directly)
// and to avoid the dependency.
const (
offset64 uint64 = 14695981039346656037
prime64 uint64 = 1099511628211
)
func fnv(h uint64, x byte) uint64 {
h ^= uint64(x)
h *= prime64
return h
}
func fnvString(h uint64, x string) uint64 {
for i := 0; i < len(x); i++ {
h ^= uint64(x[i])
h *= prime64
}
return h
}
func fnvUint64(h uint64, x uint64) uint64 {
for i := 0; i < 8; i++ {
h ^= uint64(x & 0xFF)
x >>= 8
h *= prime64
}
return h
}
func fnvUint32(h uint64, x uint32) uint64 {
for i := 0; i < 4; i++ {
h ^= uint64(x & 0xFF)
x >>= 8
h *= prime64
}
return h
}

2
src/cmd/vendor/modules.txt vendored
View File

@ -48,6 +48,7 @@ golang.org/x/sys/windows
golang.org/x/term golang.org/x/term
# golang.org/x/tools v0.8.1-0.20230508195130-8f7fb01dd429 # golang.org/x/tools v0.8.1-0.20230508195130-8f7fb01dd429
## explicit; go 1.18 ## explicit; go 1.18
golang.org/x/tools/cmd/bisect
golang.org/x/tools/cover golang.org/x/tools/cover
golang.org/x/tools/go/analysis golang.org/x/tools/go/analysis
golang.org/x/tools/go/analysis/internal/analysisflags golang.org/x/tools/go/analysis/internal/analysisflags
@ -89,5 +90,6 @@ golang.org/x/tools/go/ast/inspector
golang.org/x/tools/go/cfg golang.org/x/tools/go/cfg
golang.org/x/tools/go/types/objectpath golang.org/x/tools/go/types/objectpath
golang.org/x/tools/go/types/typeutil golang.org/x/tools/go/types/typeutil
golang.org/x/tools/internal/bisect
golang.org/x/tools/internal/facts golang.org/x/tools/internal/facts
golang.org/x/tools/internal/typeparams golang.org/x/tools/internal/typeparams