go noder 源码
golang noder 代码
文件路径：/src/cmd/compile/internal/noder/noder.go
// Copyright 2016 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 noder
import (
"errors"
"fmt"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"unicode"
"unicode/utf8"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/syntax"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/objabi"
"cmd/internal/src"
)
func LoadPackage(filenames []string) {
base.Timer.Start("fe", "parse")
// Limit the number of simultaneously open files.
sem := make(chan struct{}, runtime.GOMAXPROCS(0)+10)
noders := make([]*noder, len(filenames))
for i := range noders {
p := noder{
err: make(chan syntax.Error),
}
noders[i] = &p
}
// Move the entire syntax processing logic into a separate goroutine to avoid blocking on the "sem".
go func() {
for i, filename := range filenames {
filename := filename
p := noders[i]
sem <- struct{}{}
go func() {
defer func() { <-sem }()
defer close(p.err)
fbase := syntax.NewFileBase(filename)
f, err := os.Open(filename)
if err != nil {
p.error(syntax.Error{Msg: err.Error()})
return
}
defer f.Close()
p.file, _ = syntax.Parse(fbase, f, p.error, p.pragma, syntax.CheckBranches) // errors are tracked via p.error
}()
}
}()
var lines uint
for _, p := range noders {
for e := range p.err {
p.errorAt(e.Pos, "%s", e.Msg)
}
if p.file == nil {
base.ErrorExit()
}
lines += p.file.EOF.Line()
}
base.Timer.AddEvent(int64(lines), "lines")
if base.Debug.Unified != 0 {
unified(noders)
return
}
// Use types2 to type-check and generate IR.
check2(noders)
}
func (p *noder) errorAt(pos syntax.Pos, format string, args ...interface{}) {
base.ErrorfAt(p.makeXPos(pos), format, args...)
}
// trimFilename returns the "trimmed" filename of b, which is the
// absolute filename after applying -trimpath processing. This
// filename form is suitable for use in object files and export data.
//
// If b's filename has already been trimmed (i.e., because it was read
// in from an imported package's export data), then the filename is
// returned unchanged.
func trimFilename(b *syntax.PosBase) string {
filename := b.Filename()
if !b.Trimmed() {
dir := ""
if b.IsFileBase() {
dir = base.Ctxt.Pathname
}
filename = objabi.AbsFile(dir, filename, base.Flag.TrimPath)
}
return filename
}
// noder transforms package syntax's AST into a Node tree.
type noder struct {
posMap
file *syntax.File
linknames []linkname
pragcgobuf [][]string
err chan syntax.Error
importedUnsafe bool
importedEmbed bool
}
// linkname records a //go:linkname directive.
type linkname struct {
pos syntax.Pos
local string
remote string
}
func (p *noder) processPragmas() {
for _, l := range p.linknames {
if !p.importedUnsafe {
p.errorAt(l.pos, "//go:linkname only allowed in Go files that import \"unsafe\"")
continue
}
n := ir.AsNode(typecheck.Lookup(l.local).Def)
if n == nil || n.Op() != ir.ONAME {
p.errorAt(l.pos, "//go:linkname must refer to declared function or variable")
continue
}
if n.Sym().Linkname != "" {
p.errorAt(l.pos, "duplicate //go:linkname for %s", l.local)
continue
}
n.Sym().Linkname = l.remote
}
typecheck.Target.CgoPragmas = append(typecheck.Target.CgoPragmas, p.pragcgobuf...)
}
var unOps = [...]ir.Op{
syntax.Recv: ir.ORECV,
syntax.Mul: ir.ODEREF,
syntax.And: ir.OADDR,
syntax.Not: ir.ONOT,
syntax.Xor: ir.OBITNOT,
syntax.Add: ir.OPLUS,
syntax.Sub: ir.ONEG,
}
var binOps = [...]ir.Op{
syntax.OrOr: ir.OOROR,
syntax.AndAnd: ir.OANDAND,
syntax.Eql: ir.OEQ,
syntax.Neq: ir.ONE,
syntax.Lss: ir.OLT,
syntax.Leq: ir.OLE,
syntax.Gtr: ir.OGT,
syntax.Geq: ir.OGE,
syntax.Add: ir.OADD,
syntax.Sub: ir.OSUB,
syntax.Or: ir.OOR,
syntax.Xor: ir.OXOR,
syntax.Mul: ir.OMUL,
syntax.Div: ir.ODIV,
syntax.Rem: ir.OMOD,
syntax.And: ir.OAND,
syntax.AndNot: ir.OANDNOT,
syntax.Shl: ir.OLSH,
syntax.Shr: ir.ORSH,
}
func wrapname(pos src.XPos, x ir.Node) ir.Node {
// These nodes do not carry line numbers.
// Introduce a wrapper node to give them the correct line.
switch x.Op() {
case ir.OTYPE, ir.OLITERAL:
if x.Sym() == nil {
break
}
fallthrough
case ir.ONAME, ir.ONONAME:
p := ir.NewParenExpr(pos, x)
p.SetImplicit(true)
return p
}
return x
}
// error is called concurrently if files are parsed concurrently.
func (p *noder) error(err error) {
p.err <- err.(syntax.Error)
}
// pragmas that are allowed in the std lib, but don't have
// a syntax.Pragma value (see lex.go) associated with them.
var allowedStdPragmas = map[string]bool{
"go:cgo_export_static": true,
"go:cgo_export_dynamic": true,
"go:cgo_import_static": true,
"go:cgo_import_dynamic": true,
"go:cgo_ldflag": true,
"go:cgo_dynamic_linker": true,
"go:embed": true,
"go:generate": true,
}
// *pragmas is the value stored in a syntax.pragmas during parsing.
type pragmas struct {
Flag ir.PragmaFlag // collected bits
Pos []pragmaPos // position of each individual flag
Embeds []pragmaEmbed
}
type pragmaPos struct {
Flag ir.PragmaFlag
Pos syntax.Pos
}
type pragmaEmbed struct {
Pos syntax.Pos
Patterns []string
}
func (p *noder) checkUnusedDuringParse(pragma *pragmas) {
for _, pos := range pragma.Pos {
if pos.Flag&pragma.Flag != 0 {
p.error(syntax.Error{Pos: pos.Pos, Msg: "misplaced compiler directive"})
}
}
if len(pragma.Embeds) > 0 {
for _, e := range pragma.Embeds {
p.error(syntax.Error{Pos: e.Pos, Msg: "misplaced go:embed directive"})
}
}
}
// pragma is called concurrently if files are parsed concurrently.
func (p *noder) pragma(pos syntax.Pos, blankLine bool, text string, old syntax.Pragma) syntax.Pragma {
pragma, _ := old.(*pragmas)
if pragma == nil {
pragma = new(pragmas)
}
if text == "" {
// unused pragma; only called with old != nil.
p.checkUnusedDuringParse(pragma)
return nil
}
if strings.HasPrefix(text, "line ") {
// line directives are handled by syntax package
panic("unreachable")
}
if !blankLine {
// directive must be on line by itself
p.error(syntax.Error{Pos: pos, Msg: "misplaced compiler directive"})
return pragma
}
switch {
case strings.HasPrefix(text, "go:linkname "):
f := strings.Fields(text)
if !(2 <= len(f) && len(f) <= 3) {
p.error(syntax.Error{Pos: pos, Msg: "usage: //go:linkname localname [linkname]"})
break
}
// The second argument is optional. If omitted, we use
// the default object symbol name for this and
// linkname only serves to mark this symbol as
// something that may be referenced via the object
// symbol name from another package.
var target string
if len(f) == 3 {
target = f[2]
} else if base.Ctxt.Pkgpath != "" {
// Use the default object symbol name if the
// user didn't provide one.
target = objabi.PathToPrefix(base.Ctxt.Pkgpath) + "." + f[1]
} else {
p.error(syntax.Error{Pos: pos, Msg: "//go:linkname requires linkname argument or -p compiler flag"})
break
}
p.linknames = append(p.linknames, linkname{pos, f[1], target})
case text == "go:embed", strings.HasPrefix(text, "go:embed "):
args, err := parseGoEmbed(text[len("go:embed"):])
if err != nil {
p.error(syntax.Error{Pos: pos, Msg: err.Error()})
}
if len(args) == 0 {
p.error(syntax.Error{Pos: pos, Msg: "usage: //go:embed pattern..."})
break
}
pragma.Embeds = append(pragma.Embeds, pragmaEmbed{pos, args})
case strings.HasPrefix(text, "go:cgo_import_dynamic "):
// This is permitted for general use because Solaris
// code relies on it in golang.org/x/sys/unix and others.
fields := pragmaFields(text)
if len(fields) >= 4 {
lib := strings.Trim(fields[3], `"`)
if lib != "" && !safeArg(lib) && !isCgoGeneratedFile(pos) {
p.error(syntax.Error{Pos: pos, Msg: fmt.Sprintf("invalid library name %q in cgo_import_dynamic directive", lib)})
}
p.pragcgo(pos, text)
pragma.Flag |= pragmaFlag("go:cgo_import_dynamic")
break
}
fallthrough
case strings.HasPrefix(text, "go:cgo_"):
// For security, we disallow //go:cgo_* directives other
// than cgo_import_dynamic outside cgo-generated files.
// Exception: they are allowed in the standard library, for runtime and syscall.
if !isCgoGeneratedFile(pos) && !base.Flag.Std {
p.error(syntax.Error{Pos: pos, Msg: fmt.Sprintf("//%s only allowed in cgo-generated code", text)})
}
p.pragcgo(pos, text)
fallthrough // because of //go:cgo_unsafe_args
default:
verb := text
if i := strings.Index(text, " "); i >= 0 {
verb = verb[:i]
}
flag := pragmaFlag(verb)
const runtimePragmas = ir.Systemstack | ir.Nowritebarrier | ir.Nowritebarrierrec | ir.Yeswritebarrierrec
if !base.Flag.CompilingRuntime && flag&runtimePragmas != 0 {
p.error(syntax.Error{Pos: pos, Msg: fmt.Sprintf("//%s only allowed in runtime", verb)})
}
if flag == ir.UintptrKeepAlive && !base.Flag.Std {
p.error(syntax.Error{Pos: pos, Msg: fmt.Sprintf("//%s is only allowed in the standard library", verb)})
}
if flag == 0 && !allowedStdPragmas[verb] && base.Flag.Std {
p.error(syntax.Error{Pos: pos, Msg: fmt.Sprintf("//%s is not allowed in the standard library", verb)})
}
pragma.Flag |= flag
pragma.Pos = append(pragma.Pos, pragmaPos{flag, pos})
}
return pragma
}
// isCgoGeneratedFile reports whether pos is in a file
// generated by cgo, which is to say a file with name
// beginning with "_cgo_". Such files are allowed to
// contain cgo directives, and for security reasons
// (primarily misuse of linker flags), other files are not.
// See golang.org/issue/23672.
func isCgoGeneratedFile(pos syntax.Pos) bool {
return strings.HasPrefix(filepath.Base(trimFilename(pos.Base())), "_cgo_")
}
// safeArg reports whether arg is a "safe" command-line argument,
// meaning that when it appears in a command-line, it probably
// doesn't have some special meaning other than its own name.
// This is copied from SafeArg in cmd/go/internal/load/pkg.go.
func safeArg(name string) bool {
if name == "" {
return false
}
c := name[0]
return '0' <= c && c <= '9' || 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || c == '.' || c == '_' || c == '/' || c >= utf8.RuneSelf
}
// parseGoEmbed parses the text following "//go:embed" to extract the glob patterns.
// It accepts unquoted space-separated patterns as well as double-quoted and back-quoted Go strings.
// go/build/read.go also processes these strings and contains similar logic.
func parseGoEmbed(args string) ([]string, error) {
var list []string
for args = strings.TrimSpace(args); args != ""; args = strings.TrimSpace(args) {
var path string
Switch:
switch args[0] {
default:
i := len(args)
for j, c := range args {
if unicode.IsSpace(c) {
i = j
break
}
}
path = args[:i]
args = args[i:]
case '`':
i := strings.Index(args[1:], "`")
if i < 0 {
return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
}
path = args[1 : 1+i]
args = args[1+i+1:]
case '"':
i := 1
for ; i < len(args); i++ {
if args[i] == '\\' {
i++
continue
}
if args[i] == '"' {
q, err := strconv.Unquote(args[:i+1])
if err != nil {
return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args[:i+1])
}
path = q
args = args[i+1:]
break Switch
}
}
if i >= len(args) {
return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
}
}
if args != "" {
r, _ := utf8.DecodeRuneInString(args)
if !unicode.IsSpace(r) {
return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
}
}
list = append(list, path)
}
return list, nil
}
// A function named init is a special case.
// It is called by the initialization before main is run.
// To make it unique within a package and also uncallable,
// the name, normally "pkg.init", is altered to "pkg.init.0".
var renameinitgen int
func Renameinit() *types.Sym {
s := typecheck.LookupNum("init.", renameinitgen)
renameinitgen++
return s
}
func varEmbed(makeXPos func(syntax.Pos) src.XPos, name *ir.Name, decl *syntax.VarDecl, pragma *pragmas, haveEmbed bool) {
pragmaEmbeds := pragma.Embeds
pragma.Embeds = nil
if len(pragmaEmbeds) == 0 {
return
}
if err := checkEmbed(decl, haveEmbed, typecheck.DeclContext != ir.PEXTERN); err != nil {
base.ErrorfAt(makeXPos(pragmaEmbeds[0].Pos), "%s", err)
return
}
var embeds []ir.Embed
for _, e := range pragmaEmbeds {
embeds = append(embeds, ir.Embed{Pos: makeXPos(e.Pos), Patterns: e.Patterns})
}
typecheck.Target.Embeds = append(typecheck.Target.Embeds, name)
name.Embed = &embeds
}
func checkEmbed(decl *syntax.VarDecl, haveEmbed, withinFunc bool) error {
switch {
case !haveEmbed:
return errors.New("go:embed only allowed in Go files that import \"embed\"")
case len(decl.NameList) > 1:
return errors.New("go:embed cannot apply to multiple vars")
case decl.Values != nil:
return errors.New("go:embed cannot apply to var with initializer")
case decl.Type == nil:
// Should not happen, since Values == nil now.
return errors.New("go:embed cannot apply to var without type")
case withinFunc:
return errors.New("go:embed cannot apply to var inside func")
case !types.AllowsGoVersion(1, 16):
return fmt.Errorf("go:embed requires go1.16 or later (-lang was set to %s; check go.mod)", base.Flag.Lang)
default:
return nil
}
}
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