internal/buildcfg: move build configuration out of cmd/internal/objabi

[gostls13.git] / src / cmd / compile / internal / logopt / log_opts.go

// Copyright 2019 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 logopt

import (
        "cmd/internal/obj"
        "cmd/internal/src"
        "encoding/json"
        "fmt"
        "internal/buildcfg"
        "io"
        "log"
        "net/url"
        "os"
        "path/filepath"
        "sort"
        "strconv"
        "strings"
        "sync"
        "unicode"
)

// This implements (non)optimization logging for -json option to the Go compiler
// The option is -json 0,<destination>.
//
// 0 is the version number; to avoid the need for synchronized updates, if
// new versions of the logging appear, the compiler will support both, for a while,
// and clients will specify what they need.
//
// <destination> is a directory.
// Directories are specified with a leading / or os.PathSeparator,
// or more explicitly with file://directory.  The second form is intended to
// deal with corner cases on Windows, and to allow specification of a relative
// directory path (which is normally a bad idea, because the local directory
// varies a lot in a build, especially with modules and/or vendoring, and may
// not be writeable).
//
// For each package pkg compiled, a url.PathEscape(pkg)-named subdirectory
// is created.  For each source file.go in that package that generates
// diagnostics (no diagnostics means no file),
// a url.PathEscape(file)+".json"-named file is created and contains the
// logged diagnostics.
//
// For example, "cmd%2Finternal%2Fdwarf/%3Cautogenerated%3E.json"
// for "cmd/internal/dwarf" and <autogenerated> (which is not really a file, but the compiler sees it)
//
// If the package string is empty, it is replaced internally with string(0) which encodes to %00.
//
// Each log file begins with a JSON record identifying version,
// platform, and other context, followed by optimization-relevant
// LSP Diagnostic records, one per line (LSP version 3.15, no difference from 3.14 on the subset used here
// see https://microsoft.github.io/language-server-protocol/specifications/specification-3-15/ )
//
// The fields of a Diagnostic are used in the following way:
// Range: the outermost source position, for now begin and end are equal.
// Severity: (always) SeverityInformation (3)
// Source: (always) "go compiler"
// Code: a string describing the missed optimization, e.g., "nilcheck", "cannotInline", "isInBounds", "escape"
// Message: depending on code, additional information, e.g., the reason a function cannot be inlined.
// RelatedInformation: if the missed optimization actually occurred at a function inlined at Range,
//    then the sequence of inlined locations appears here, from (second) outermost to innermost,
//    each with message="inlineLoc".
//
//    In the case of escape analysis explanations, after any outer inlining locations,
//    the lines of the explanation appear, each potentially followed with its own inlining
//    location if the escape flow occurred within an inlined function.
//
// For example <destination>/cmd%2Fcompile%2Finternal%2Fssa/prove.json
// might begin with the following line (wrapped for legibility):
//
// {"version":0,"package":"cmd/compile/internal/ssa","goos":"darwin","goarch":"amd64",
//  "gc_version":"devel +e1b9a57852 Fri Nov 1 15:07:00 2019 -0400",
//  "file":"/Users/drchase/work/go/src/cmd/compile/internal/ssa/prove.go"}
//
// and later contain (also wrapped for legibility):
//
// {"range":{"start":{"line":191,"character":24},"end":{"line":191,"character":24}},
//  "severity":3,"code":"nilcheck","source":"go compiler","message":"",
//  "relatedInformation":[
//    {"location":{"uri":"file:///Users/drchase/work/go/src/cmd/compile/internal/ssa/func.go",
//                 "range":{"start":{"line":153,"character":16},"end":{"line":153,"character":16}}},
//     "message":"inlineLoc"}]}
//
// That is, at prove.go (implicit from context, provided in both filename and header line),
// line 191, column 24, a nilcheck occurred in the generated code.
// The relatedInformation indicates that this code actually came from
// an inlined call to func.go, line 153, character 16.
//
// prove.go:191:
//      ft.orderS = f.newPoset()
// func.go:152 and 153:
//  func (f *Func) newPoset() *poset {
//          if len(f.Cache.scrPoset) > 0 {
//
// In the case that the package is empty, the string(0) package name is also used in the header record, for example
//
//  go tool compile -json=0,file://logopt x.go       # no -p option to set the package
//  head -1 logopt/%00/x.json
//  {"version":0,"package":"\u0000","goos":"darwin","goarch":"amd64","gc_version":"devel +86487adf6a Thu Nov 7 19:34:56 2019 -0500","file":"x.go"}

type VersionHeader struct {
        Version   int    `json:"version"`
        Package   string `json:"package"`
        Goos      string `json:"goos"`
        Goarch    string `json:"goarch"`
        GcVersion string `json:"gc_version"`
        File      string `json:"file,omitempty"` // LSP requires an enclosing resource, i.e., a file
}

// DocumentURI, Position, Range, Location, Diagnostic, DiagnosticRelatedInformation all reuse json definitions from gopls.
// See https://github.com/golang/tools/blob/22afafe3322a860fcd3d88448768f9db36f8bc5f/internal/lsp/protocol/tsprotocol.go

type DocumentURI string

type Position struct {
        Line      uint `json:"line"`      // gopls uses float64, but json output is the same for integers
        Character uint `json:"character"` // gopls uses float64, but json output is the same for integers
}

// A Range in a text document expressed as (zero-based) start and end positions.
// A range is comparable to a selection in an editor. Therefore the end position is exclusive.
// If you want to specify a range that contains a line including the line ending character(s)
// then use an end position denoting the start of the next line.
type Range struct {
        /*Start defined:
         * The range's start position
         */
        Start Position `json:"start"`

        /*End defined:
         * The range's end position
         */
        End Position `json:"end"` // exclusive
}

// A Location represents a location inside a resource, such as a line inside a text file.
type Location struct {
        // URI is
        URI DocumentURI `json:"uri"`

        // Range is
        Range Range `json:"range"`
}

/* DiagnosticRelatedInformation defined:
 * Represents a related message and source code location for a diagnostic. This should be
 * used to point to code locations that cause or related to a diagnostics, e.g when duplicating
 * a symbol in a scope.
 */
type DiagnosticRelatedInformation struct {

        /*Location defined:
         * The location of this related diagnostic information.
         */
        Location Location `json:"location"`

        /*Message defined:
         * The message of this related diagnostic information.
         */
        Message string `json:"message"`
}

// DiagnosticSeverity defines constants
type DiagnosticSeverity uint

const (
        /*SeverityInformation defined:
         * Reports an information.
         */
        SeverityInformation DiagnosticSeverity = 3
)

// DiagnosticTag defines constants
type DiagnosticTag uint

/*Diagnostic defined:
 * Represents a diagnostic, such as a compiler error or warning. Diagnostic objects
 * are only valid in the scope of a resource.
 */
type Diagnostic struct {

        /*Range defined:
         * The range at which the message applies
         */
        Range Range `json:"range"`

        /*Severity defined:
         * The diagnostic's severity. Can be omitted. If omitted it is up to the
         * client to interpret diagnostics as error, warning, info or hint.
         */
        Severity DiagnosticSeverity `json:"severity,omitempty"` // always SeverityInformation for optimizer logging.

        /*Code defined:
         * The diagnostic's code, which usually appear in the user interface.
         */
        Code string `json:"code,omitempty"` // LSP uses 'number | string' = gopls interface{}, but only string here, e.g. "boundsCheck", "nilcheck", etc.

        /*Source defined:
         * A human-readable string describing the source of this
         * diagnostic, e.g. 'typescript' or 'super lint'. It usually
         * appears in the user interface.
         */
        Source string `json:"source,omitempty"` // "go compiler"

        /*Message defined:
         * The diagnostic's message. It usually appears in the user interface
         */
        Message string `json:"message"` // sometimes used, provides additional information.

        /*Tags defined:
         * Additional metadata about the diagnostic.
         */
        Tags []DiagnosticTag `json:"tags,omitempty"` // always empty for logging optimizations.

        /*RelatedInformation defined:
         * An array of related diagnostic information, e.g. when symbol-names within
         * a scope collide all definitions can be marked via this property.
         */
        RelatedInformation []DiagnosticRelatedInformation `json:"relatedInformation,omitempty"`
}

// A LoggedOpt is what the compiler produces and accumulates,
// to be converted to JSON for human or IDE consumption.
type LoggedOpt struct {
        pos          src.XPos      // Source code position at which the event occurred. If it is inlined, outer and all inlined locations will appear in JSON.
        compilerPass string        // Compiler pass.  For human/adhoc consumption; does not appear in JSON (yet)
        functionName string        // Function name.  For human/adhoc consumption; does not appear in JSON (yet)
        what         string        // The (non) optimization; "nilcheck", "boundsCheck", "inline", "noInline"
        target       []interface{} // Optional target(s) or parameter(s) of "what" -- what was inlined, why it was not, size of copy, etc. 1st is most important/relevant.
}

type logFormat uint8

const (
        None  logFormat = iota
        Json0           // version 0 for LSP 3.14, 3.15; future versions of LSP may change the format and the compiler may need to support both as clients are updated.
)

var Format = None
var dest string

// LogJsonOption parses and validates the version,directory value attached to the -json compiler flag.
func LogJsonOption(flagValue string) {
        version, directory := parseLogFlag("json", flagValue)
        if version != 0 {
                log.Fatal("-json version must be 0")
        }
        dest = checkLogPath(directory)
        Format = Json0
}

// parseLogFlag checks the flag passed to -json
// for version,destination format and returns the two parts.
func parseLogFlag(flag, value string) (version int, directory string) {
        if Format != None {
                log.Fatal("Cannot repeat -json flag")
        }
        commaAt := strings.Index(value, ",")
        if commaAt <= 0 {
                log.Fatalf("-%s option should be '<version>,<destination>' where <version> is a number", flag)
        }
        v, err := strconv.Atoi(value[:commaAt])
        if err != nil {
                log.Fatalf("-%s option should be '<version>,<destination>' where <version> is a number: err=%v", flag, err)
        }
        version = v
        directory = value[commaAt+1:]
        return
}

// isWindowsDriveURI returns true if the file URI is of the format used by
// Windows URIs. The url.Parse package does not specially handle Windows paths
// (see golang/go#6027), so we check if the URI path has a drive prefix (e.g. "/C:").
// (copied from tools/internal/span/uri.go)
// this is less comprehensive that the processing in filepath.IsAbs on Windows.
func isWindowsDriveURIPath(uri string) bool {
        if len(uri) < 4 {
                return false
        }
        return uri[0] == '/' && unicode.IsLetter(rune(uri[1])) && uri[2] == ':'
}

func parseLogPath(destination string) (string, string) {
        if filepath.IsAbs(destination) {
                return filepath.Clean(destination), ""
        }
        if strings.HasPrefix(destination, "file://") { // IKWIAD, or Windows C:\foo\bar\baz
                uri, err := url.Parse(destination)
                if err != nil {
                        return "", fmt.Sprintf("optimizer logging destination looked like file:// URI but failed to parse: err=%v", err)
                }
                destination = uri.Host + uri.Path
                if isWindowsDriveURIPath(destination) {
                        // strip leading / from /C:
                        // unlike tools/internal/span/uri.go, do not uppercase the drive letter -- let filepath.Clean do what it does.
                        destination = destination[1:]
                }
                return filepath.Clean(destination), ""
        }
        return "", fmt.Sprintf("optimizer logging destination %s was neither %s-prefixed directory nor file://-prefixed file URI", destination, string(filepath.Separator))
}

// checkLogPath does superficial early checking of the string specifying
// the directory to which optimizer logging is directed, and if
// it passes the test, stores the string in LO_dir
func checkLogPath(destination string) string {
        path, complaint := parseLogPath(destination)
        if complaint != "" {
                log.Fatalf(complaint)
        }
        err := os.MkdirAll(path, 0755)
        if err != nil {
                log.Fatalf("optimizer logging destination '<version>,<directory>' but could not create <directory>: err=%v", err)
        }
        return path
}

var loggedOpts []*LoggedOpt
var mu = sync.Mutex{} // mu protects loggedOpts.

// NewLoggedOpt allocates a new LoggedOpt, to later be passed to either NewLoggedOpt or LogOpt as "args".
// Pos is the source position (including inlining), what is the message, pass is which pass created the message,
// funcName is the name of the function
// A typical use for this to accumulate an explanation for a missed optimization, for example, why did something escape?
func NewLoggedOpt(pos src.XPos, what, pass, funcName string, args ...interface{}) *LoggedOpt {
        pass = strings.Replace(pass, " ", "_", -1)
        return &LoggedOpt{pos, pass, funcName, what, args}
}

// Logopt logs information about a (usually missed) optimization performed by the compiler.
// Pos is the source position (including inlining), what is the message, pass is which pass created the message,
// funcName is the name of the function
func LogOpt(pos src.XPos, what, pass, funcName string, args ...interface{}) {
        if Format == None {
                return
        }
        lo := NewLoggedOpt(pos, what, pass, funcName, args...)
        mu.Lock()
        defer mu.Unlock()
        // Because of concurrent calls from back end, no telling what the order will be, but is stable-sorted by outer Pos before use.
        loggedOpts = append(loggedOpts, lo)
}

// Enabled returns whether optimization logging is enabled.
func Enabled() bool {
        switch Format {
        case None:
                return false
        case Json0:
                return true
        }
        panic("Unexpected optimizer-logging level")
}

// byPos sorts diagnostics by source position.
type byPos struct {
        ctxt *obj.Link
        a    []*LoggedOpt
}

func (x byPos) Len() int { return len(x.a) }
func (x byPos) Less(i, j int) bool {
        return x.ctxt.OutermostPos(x.a[i].pos).Before(x.ctxt.OutermostPos(x.a[j].pos))
}
func (x byPos) Swap(i, j int) { x.a[i], x.a[j] = x.a[j], x.a[i] }

func writerForLSP(subdirpath, file string) io.WriteCloser {
        basename := file
        lastslash := strings.LastIndexAny(basename, "\\/")
        if lastslash != -1 {
                basename = basename[lastslash+1:]
        }
        lastdot := strings.LastIndex(basename, ".go")
        if lastdot != -1 {
                basename = basename[:lastdot]
        }
        basename = pathEscape(basename)

        // Assume a directory, make a file
        p := filepath.Join(subdirpath, basename+".json")
        w, err := os.Create(p)
        if err != nil {
                log.Fatalf("Could not create file %s for logging optimizer actions, %v", p, err)
        }
        return w
}

func fixSlash(f string) string {
        if os.PathSeparator == '/' {
                return f
        }
        return strings.Replace(f, string(os.PathSeparator), "/", -1)
}

func uriIfy(f string) DocumentURI {
        url := url.URL{
                Scheme: "file",
                Path:   fixSlash(f),
        }
        return DocumentURI(url.String())
}

// Return filename, replacing a first occurrence of $GOROOT with the
// actual value of the GOROOT (because LSP does not speak "$GOROOT").
func uprootedPath(filename string) string {
        if !strings.HasPrefix(filename, "$GOROOT/") {
                return filename
        }
        return buildcfg.GOROOT + filename[len("$GOROOT"):]
}

// FlushLoggedOpts flushes all the accumulated optimization log entries.
func FlushLoggedOpts(ctxt *obj.Link, slashPkgPath string) {
        if Format == None {
                return
        }

        sort.Stable(byPos{ctxt, loggedOpts}) // Stable is necessary to preserve the per-function order, which is repeatable.
        switch Format {

        case Json0: // LSP 3.15
                var posTmp []src.Pos
                var encoder *json.Encoder
                var w io.WriteCloser

                if slashPkgPath == "" {
                        slashPkgPath = "\000"
                }
                subdirpath := filepath.Join(dest, pathEscape(slashPkgPath))
                err := os.MkdirAll(subdirpath, 0755)
                if err != nil {
                        log.Fatalf("Could not create directory %s for logging optimizer actions, %v", subdirpath, err)
                }
                diagnostic := Diagnostic{Source: "go compiler", Severity: SeverityInformation}

                // For LSP, make a subdirectory for the package, and for each file foo.go, create foo.json in that subdirectory.
                currentFile := ""
                for _, x := range loggedOpts {
                        posTmp, p0 := x.parsePos(ctxt, posTmp)
                        p0f := uprootedPath(p0.Filename())

                        if currentFile != p0f {
                                if w != nil {
                                        w.Close()
                                }
                                currentFile = p0f
                                w = writerForLSP(subdirpath, currentFile)
                                encoder = json.NewEncoder(w)
                                encoder.Encode(VersionHeader{Version: 0, Package: slashPkgPath, Goos: buildcfg.GOOS, Goarch: buildcfg.GOARCH, GcVersion: buildcfg.Version, File: currentFile})
                        }

                        // The first "target" is the most important one.
                        var target string
                        if len(x.target) > 0 {
                                target = fmt.Sprint(x.target[0])
                        }

                        diagnostic.Code = x.what
                        diagnostic.Message = target
                        diagnostic.Range = newPointRange(p0)
                        diagnostic.RelatedInformation = diagnostic.RelatedInformation[:0]

                        appendInlinedPos(posTmp, &diagnostic)

                        // Diagnostic explanation is stored in RelatedInformation after inlining info
                        if len(x.target) > 1 {
                                switch y := x.target[1].(type) {
                                case []*LoggedOpt:
                                        for _, z := range y {
                                                posTmp, p0 := z.parsePos(ctxt, posTmp)
                                                loc := newLocation(p0)
                                                msg := z.what
                                                if len(z.target) > 0 {
                                                        msg = msg + ": " + fmt.Sprint(z.target[0])
                                                }

                                                diagnostic.RelatedInformation = append(diagnostic.RelatedInformation, DiagnosticRelatedInformation{Location: loc, Message: msg})
                                                appendInlinedPos(posTmp, &diagnostic)
                                        }
                                }
                        }

                        encoder.Encode(diagnostic)
                }
                if w != nil {
                        w.Close()
                }
        }
}

// newPointRange returns a single-position Range for the compiler source location p.
func newPointRange(p src.Pos) Range {
        return Range{Start: Position{p.Line(), p.Col()},
                End: Position{p.Line(), p.Col()}}
}

// newLocation returns the Location for the compiler source location p
func newLocation(p src.Pos) Location {
        loc := Location{URI: uriIfy(uprootedPath(p.Filename())), Range: newPointRange(p)}
        return loc
}

// appendInlinedPos extracts inlining information from posTmp and append it to diagnostic
func appendInlinedPos(posTmp []src.Pos, diagnostic *Diagnostic) {
        for i := 1; i < len(posTmp); i++ {
                p := posTmp[i]
                loc := newLocation(p)
                diagnostic.RelatedInformation = append(diagnostic.RelatedInformation, DiagnosticRelatedInformation{Location: loc, Message: "inlineLoc"})
        }
}

func (x *LoggedOpt) parsePos(ctxt *obj.Link, posTmp []src.Pos) ([]src.Pos, src.Pos) {
        posTmp = ctxt.AllPos(x.pos, posTmp)
        // Reverse posTmp to put outermost first.
        l := len(posTmp)
        for i := 0; i < l/2; i++ {
                posTmp[i], posTmp[l-i-1] = posTmp[l-i-1], posTmp[i]
        }
        p0 := posTmp[0]
        return posTmp, p0
}