--- /dev/null
+// UNREVIEWED
+
+// Copyright 2021 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 gcimporter
+
+import (
+ "go/token"
+ "go/types"
+ "internal/pkgbits"
+)
+
+// A pkgReader holds the shared state for reading a unified IR package
+// description.
+type pkgReader struct {
+ pkgbits.PkgDecoder
+
+ fake fakeFileSet
+
+ ctxt *types.Context
+ imports map[string]*types.Package // previously imported packages, indexed by path
+
+ // lazily initialized arrays corresponding to the unified IR
+ // PosBase, Pkg, and Type sections, respectively.
+ posBases []string // position bases (i.e., file names)
+ pkgs []*types.Package
+ typs []types.Type
+
+ // laterFns holds functions that need to be invoked at the end of
+ // import reading.
+ laterFns []func()
+}
+
+// later adds a function to be invoked at the end of import reading.
+func (pr *pkgReader) later(fn func()) {
+ pr.laterFns = append(pr.laterFns, fn)
+}
+
+// readUnifiedPackage reads a package description from the given
+// unified IR export data decoder.
+func readUnifiedPackage(fset *token.FileSet, ctxt *types.Context, imports map[string]*types.Package, input pkgbits.PkgDecoder) *types.Package {
+ pr := pkgReader{
+ PkgDecoder: input,
+
+ fake: fakeFileSet{
+ fset: fset,
+ files: make(map[string]*fileInfo),
+ },
+
+ ctxt: ctxt,
+ imports: imports,
+
+ posBases: make([]string, input.NumElems(pkgbits.RelocPosBase)),
+ pkgs: make([]*types.Package, input.NumElems(pkgbits.RelocPkg)),
+ typs: make([]types.Type, input.NumElems(pkgbits.RelocType)),
+ }
+ defer pr.fake.setLines()
+
+ r := pr.newReader(pkgbits.RelocMeta, pkgbits.PublicRootIdx, pkgbits.SyncPublic)
+ pkg := r.pkg()
+ r.Bool() // has init
+
+ for i, n := 0, r.Len(); i < n; i++ {
+ // As if r.obj(), but avoiding the Scope.Lookup call,
+ // to avoid eager loading of imports.
+ r.Sync(pkgbits.SyncObject)
+ assert(!r.Bool())
+ r.p.objIdx(r.Reloc(pkgbits.RelocObj))
+ assert(r.Len() == 0)
+ }
+
+ r.Sync(pkgbits.SyncEOF)
+
+ for _, fn := range pr.laterFns {
+ fn()
+ }
+
+ pkg.MarkComplete()
+ return pkg
+}
+
+// A reader holds the state for reading a single unified IR element
+// within a package.
+type reader struct {
+ pkgbits.Decoder
+
+ p *pkgReader
+
+ dict *readerDict
+}
+
+// A readerDict holds the state for type parameters that parameterize
+// the current unified IR element.
+type readerDict struct {
+ // bounds is a slice of typeInfos corresponding to the underlying
+ // bounds of the element's type parameters.
+ bounds []typeInfo
+
+ // tparams is a slice of the constructed TypeParams for the element.
+ tparams []*types.TypeParam
+
+ // devived is a slice of types derived from tparams, which may be
+ // instantiated while reading the current element.
+ derived []derivedInfo
+ derivedTypes []types.Type // lazily instantiated from derived
+}
+
+func (pr *pkgReader) newReader(k pkgbits.RelocKind, idx int, marker pkgbits.SyncMarker) *reader {
+ return &reader{
+ Decoder: pr.NewDecoder(k, idx, marker),
+ p: pr,
+ }
+}
+
+// @@@ Positions
+
+func (r *reader) pos() token.Pos {
+ r.Sync(pkgbits.SyncPos)
+ if !r.Bool() {
+ return token.NoPos
+ }
+
+ // TODO(mdempsky): Delta encoding.
+ posBase := r.posBase()
+ line := r.Uint()
+ col := r.Uint()
+ return r.p.fake.pos(posBase, int(line), int(col))
+}
+
+func (r *reader) posBase() string {
+ return r.p.posBaseIdx(r.Reloc(pkgbits.RelocPosBase))
+}
+
+func (pr *pkgReader) posBaseIdx(idx int) string {
+ if b := pr.posBases[idx]; b != "" {
+ return b
+ }
+
+ r := pr.newReader(pkgbits.RelocPosBase, idx, pkgbits.SyncPosBase)
+
+ // Within types2, position bases have a lot more details (e.g.,
+ // keeping track of where //line directives appeared exactly).
+ //
+ // For go/types, we just track the file name.
+
+ filename := r.String()
+
+ if r.Bool() { // file base
+ // Was: "b = token.NewTrimmedFileBase(filename, true)"
+ } else { // line base
+ pos := r.pos()
+ line := r.Uint()
+ col := r.Uint()
+
+ // Was: "b = token.NewLineBase(pos, filename, true, line, col)"
+ _, _, _ = pos, line, col
+ }
+
+ b := filename
+ pr.posBases[idx] = b
+ return b
+}
+
+// @@@ Packages
+
+func (r *reader) pkg() *types.Package {
+ r.Sync(pkgbits.SyncPkg)
+ return r.p.pkgIdx(r.Reloc(pkgbits.RelocPkg))
+}
+
+func (pr *pkgReader) pkgIdx(idx int) *types.Package {
+ // TODO(mdempsky): Consider using some non-nil pointer to indicate
+ // the universe scope, so we don't need to keep re-reading it.
+ if pkg := pr.pkgs[idx]; pkg != nil {
+ return pkg
+ }
+
+ pkg := pr.newReader(pkgbits.RelocPkg, idx, pkgbits.SyncPkgDef).doPkg()
+ pr.pkgs[idx] = pkg
+ return pkg
+}
+
+func (r *reader) doPkg() *types.Package {
+ path := r.String()
+ if path == "builtin" {
+ return nil // universe
+ }
+ if path == "unsafe" {
+ return types.Unsafe
+ }
+ if path == "" {
+ path = r.p.PkgPath()
+ }
+
+ if pkg := r.p.imports[path]; pkg != nil {
+ return pkg
+ }
+
+ name := r.String()
+ height := r.Len()
+
+ // Was: "pkg := types.NewPackageHeight(path, name, height)"
+ pkg, _ := types.NewPackage(path, name), height
+ r.p.imports[path] = pkg
+
+ imports := make([]*types.Package, r.Len())
+ for i := range imports {
+ imports[i] = r.pkg()
+ }
+ pkg.SetImports(imports)
+
+ return pkg
+}
+
+// @@@ Types
+
+func (r *reader) typ() types.Type {
+ return r.p.typIdx(r.typInfo(), r.dict)
+}
+
+func (r *reader) typInfo() typeInfo {
+ r.Sync(pkgbits.SyncType)
+ if r.Bool() {
+ return typeInfo{idx: r.Len(), derived: true}
+ }
+ return typeInfo{idx: r.Reloc(pkgbits.RelocType), derived: false}
+}
+
+func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict) types.Type {
+ idx := info.idx
+ var where *types.Type
+ if info.derived {
+ where = &dict.derivedTypes[idx]
+ idx = dict.derived[idx].idx
+ } else {
+ where = &pr.typs[idx]
+ }
+
+ if typ := *where; typ != nil {
+ return typ
+ }
+
+ r := pr.newReader(pkgbits.RelocType, idx, pkgbits.SyncTypeIdx)
+ r.dict = dict
+
+ typ := r.doTyp()
+ assert(typ != nil)
+
+ // See comment in pkgReader.typIdx explaining how this happens.
+ if prev := *where; prev != nil {
+ return prev
+ }
+
+ *where = typ
+ return typ
+}
+
+func (r *reader) doTyp() (res types.Type) {
+ switch tag := pkgbits.CodeType(r.Code(pkgbits.SyncType)); tag {
+ default:
+ errorf("unhandled type tag: %v", tag)
+ panic("unreachable")
+
+ case pkgbits.TypeBasic:
+ return types.Typ[r.Len()]
+
+ case pkgbits.TypeNamed:
+ obj, targs := r.obj()
+ name := obj.(*types.TypeName)
+ if len(targs) != 0 {
+ t, _ := types.Instantiate(r.p.ctxt, name.Type(), targs, false)
+ return t
+ }
+ return name.Type()
+
+ case pkgbits.TypeTypeParam:
+ return r.dict.tparams[r.Len()]
+
+ case pkgbits.TypeArray:
+ len := int64(r.Uint64())
+ return types.NewArray(r.typ(), len)
+ case pkgbits.TypeChan:
+ dir := types.ChanDir(r.Len())
+ return types.NewChan(dir, r.typ())
+ case pkgbits.TypeMap:
+ return types.NewMap(r.typ(), r.typ())
+ case pkgbits.TypePointer:
+ return types.NewPointer(r.typ())
+ case pkgbits.TypeSignature:
+ return r.signature(nil, nil, nil)
+ case pkgbits.TypeSlice:
+ return types.NewSlice(r.typ())
+ case pkgbits.TypeStruct:
+ return r.structType()
+ case pkgbits.TypeInterface:
+ return r.interfaceType()
+ case pkgbits.TypeUnion:
+ return r.unionType()
+ }
+}
+
+func (r *reader) structType() *types.Struct {
+ fields := make([]*types.Var, r.Len())
+ var tags []string
+ for i := range fields {
+ pos := r.pos()
+ pkg, name := r.selector()
+ ftyp := r.typ()
+ tag := r.String()
+ embedded := r.Bool()
+
+ fields[i] = types.NewField(pos, pkg, name, ftyp, embedded)
+ if tag != "" {
+ for len(tags) < i {
+ tags = append(tags, "")
+ }
+ tags = append(tags, tag)
+ }
+ }
+ return types.NewStruct(fields, tags)
+}
+
+func (r *reader) unionType() *types.Union {
+ terms := make([]*types.Term, r.Len())
+ for i := range terms {
+ terms[i] = types.NewTerm(r.Bool(), r.typ())
+ }
+ return types.NewUnion(terms)
+}
+
+func (r *reader) interfaceType() *types.Interface {
+ methods := make([]*types.Func, r.Len())
+ embeddeds := make([]types.Type, r.Len())
+ implicit := len(methods) == 0 && len(embeddeds) == 1 && r.Bool()
+
+ for i := range methods {
+ pos := r.pos()
+ pkg, name := r.selector()
+ mtyp := r.signature(nil, nil, nil)
+ methods[i] = types.NewFunc(pos, pkg, name, mtyp)
+ }
+
+ for i := range embeddeds {
+ embeddeds[i] = r.typ()
+ }
+
+ iface := types.NewInterfaceType(methods, embeddeds)
+ if implicit {
+ iface.MarkImplicit()
+ }
+ return iface
+}
+
+func (r *reader) signature(recv *types.Var, rtparams, tparams []*types.TypeParam) *types.Signature {
+ r.Sync(pkgbits.SyncSignature)
+
+ params := r.params()
+ results := r.params()
+ variadic := r.Bool()
+
+ return types.NewSignatureType(recv, rtparams, tparams, params, results, variadic)
+}
+
+func (r *reader) params() *types.Tuple {
+ r.Sync(pkgbits.SyncParams)
+
+ params := make([]*types.Var, r.Len())
+ for i := range params {
+ params[i] = r.param()
+ }
+
+ return types.NewTuple(params...)
+}
+
+func (r *reader) param() *types.Var {
+ r.Sync(pkgbits.SyncParam)
+
+ pos := r.pos()
+ pkg, name := r.localIdent()
+ typ := r.typ()
+
+ return types.NewParam(pos, pkg, name, typ)
+}
+
+// @@@ Objects
+
+func (r *reader) obj() (types.Object, []types.Type) {
+ r.Sync(pkgbits.SyncObject)
+
+ assert(!r.Bool())
+
+ pkg, name := r.p.objIdx(r.Reloc(pkgbits.RelocObj))
+ obj := pkgScope(pkg).Lookup(name)
+
+ targs := make([]types.Type, r.Len())
+ for i := range targs {
+ targs[i] = r.typ()
+ }
+
+ return obj, targs
+}
+
+func (pr *pkgReader) objIdx(idx int) (*types.Package, string) {
+ rname := pr.newReader(pkgbits.RelocName, idx, pkgbits.SyncObject1)
+
+ objPkg, objName := rname.qualifiedIdent()
+ assert(objName != "")
+
+ tag := pkgbits.CodeObj(rname.Code(pkgbits.SyncCodeObj))
+
+ if tag == pkgbits.ObjStub {
+ assert(objPkg == nil || objPkg == types.Unsafe)
+ return objPkg, objName
+ }
+
+ if objPkg.Scope().Lookup(objName) == nil {
+ dict := pr.objDictIdx(idx)
+
+ r := pr.newReader(pkgbits.RelocObj, idx, pkgbits.SyncObject1)
+ r.dict = dict
+
+ declare := func(obj types.Object) {
+ objPkg.Scope().Insert(obj)
+ }
+
+ switch tag {
+ default:
+ panic("weird")
+
+ case pkgbits.ObjAlias:
+ pos := r.pos()
+ typ := r.typ()
+ declare(types.NewTypeName(pos, objPkg, objName, typ))
+
+ case pkgbits.ObjConst:
+ pos := r.pos()
+ typ := r.typ()
+ val := r.Value()
+ declare(types.NewConst(pos, objPkg, objName, typ, val))
+
+ case pkgbits.ObjFunc:
+ pos := r.pos()
+ tparams := r.typeParamNames()
+ sig := r.signature(nil, nil, tparams)
+ declare(types.NewFunc(pos, objPkg, objName, sig))
+
+ case pkgbits.ObjType:
+ pos := r.pos()
+
+ obj := types.NewTypeName(pos, objPkg, objName, nil)
+ named := types.NewNamed(obj, nil, nil)
+ declare(obj)
+
+ named.SetTypeParams(r.typeParamNames())
+
+ // TODO(mdempsky): Rewrite receiver types to underlying is an
+ // Interface? The go/types importer does this (I think because
+ // unit tests expected that), but cmd/compile doesn't care
+ // about it, so maybe we can avoid worrying about that here.
+ rhs := r.typ()
+ r.p.later(func() {
+ underlying := rhs.Underlying()
+ named.SetUnderlying(underlying)
+ })
+
+ for i, n := 0, r.Len(); i < n; i++ {
+ named.AddMethod(r.method())
+ }
+
+ case pkgbits.ObjVar:
+ pos := r.pos()
+ typ := r.typ()
+ declare(types.NewVar(pos, objPkg, objName, typ))
+ }
+ }
+
+ return objPkg, objName
+}
+
+func (pr *pkgReader) objDictIdx(idx int) *readerDict {
+ r := pr.newReader(pkgbits.RelocObjDict, idx, pkgbits.SyncObject1)
+
+ var dict readerDict
+
+ if implicits := r.Len(); implicits != 0 {
+ errorf("unexpected object with %v implicit type parameter(s)", implicits)
+ }
+
+ dict.bounds = make([]typeInfo, r.Len())
+ for i := range dict.bounds {
+ dict.bounds[i] = r.typInfo()
+ }
+
+ dict.derived = make([]derivedInfo, r.Len())
+ dict.derivedTypes = make([]types.Type, len(dict.derived))
+ for i := range dict.derived {
+ dict.derived[i] = derivedInfo{r.Reloc(pkgbits.RelocType), r.Bool()}
+ }
+
+ // function references follow, but reader doesn't need those
+
+ return &dict
+}
+
+func (r *reader) typeParamNames() []*types.TypeParam {
+ r.Sync(pkgbits.SyncTypeParamNames)
+
+ // Note: This code assumes it only processes objects without
+ // implement type parameters. This is currently fine, because
+ // reader is only used to read in exported declarations, which are
+ // always package scoped.
+
+ if len(r.dict.bounds) == 0 {
+ return nil
+ }
+
+ // Careful: Type parameter lists may have cycles. To allow for this,
+ // we construct the type parameter list in two passes: first we
+ // create all the TypeNames and TypeParams, then we construct and
+ // set the bound type.
+
+ r.dict.tparams = make([]*types.TypeParam, len(r.dict.bounds))
+ for i := range r.dict.bounds {
+ pos := r.pos()
+ pkg, name := r.localIdent()
+
+ tname := types.NewTypeName(pos, pkg, name, nil)
+ r.dict.tparams[i] = types.NewTypeParam(tname, nil)
+ }
+
+ typs := make([]types.Type, len(r.dict.bounds))
+ for i, bound := range r.dict.bounds {
+ typs[i] = r.p.typIdx(bound, r.dict)
+ }
+
+ // TODO(mdempsky): This is subtle, elaborate further.
+ //
+ // We have to save tparams outside of the closure, because
+ // typeParamNames() can be called multiple times with the same
+ // dictionary instance.
+ //
+ // Also, this needs to happen later to make sure SetUnderlying has
+ // been called.
+ //
+ // TODO(mdempsky): Is it safe to have a single "later" slice or do
+ // we need to have multiple passes? See comments on CL 386002 and
+ // go.dev/issue/52104.
+ tparams := r.dict.tparams
+ r.p.later(func() {
+ for i, typ := range typs {
+ tparams[i].SetConstraint(typ)
+ }
+ })
+
+ return r.dict.tparams
+}
+
+func (r *reader) method() *types.Func {
+ r.Sync(pkgbits.SyncMethod)
+ pos := r.pos()
+ pkg, name := r.selector()
+
+ rparams := r.typeParamNames()
+ sig := r.signature(r.param(), rparams, nil)
+
+ _ = r.pos() // TODO(mdempsky): Remove; this is a hacker for linker.go.
+ return types.NewFunc(pos, pkg, name, sig)
+}
+
+func (r *reader) qualifiedIdent() (*types.Package, string) { return r.ident(pkgbits.SyncSym) }
+func (r *reader) localIdent() (*types.Package, string) { return r.ident(pkgbits.SyncLocalIdent) }
+func (r *reader) selector() (*types.Package, string) { return r.ident(pkgbits.SyncSelector) }
+
+func (r *reader) ident(marker pkgbits.SyncMarker) (*types.Package, string) {
+ r.Sync(marker)
+ return r.pkg(), r.String()
+}
+
+// pkgScope returns pkg.Scope().
+// If pkg is nil, it returns types.Universe instead.
+//
+// TODO(mdempsky): Remove after x/tools can depend on Go 1.19.
+func pkgScope(pkg *types.Package) *types.Scope {
+ if pkg != nil {
+ return pkg.Scope()
+ }
+ return types.Universe
+}