src/cmd/compile/internal/noder/unified.go - go - Git at Google

 // 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 noder

 import (
 	"bytes"
 	"fmt"
 	"internal/goversion"
 	"io"
 	"runtime"
 	"sort"

 	"cmd/compile/internal/base"
 	"cmd/compile/internal/inline"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 	"cmd/compile/internal/types2"
 	"cmd/internal/src"
 )

 // localPkgReader holds the package reader used for reading the local
 // package. It exists so the unified IR linker can refer back to it
 // later.
 var localPkgReader *pkgReader

 // unified construct the local package's IR from syntax's AST.
 //
 // The pipeline contains 2 steps:
 //
 // (1) Generate package export data "stub".
 //
 // (2) Generate package IR from package export data.
 //
 // The package data "stub" at step (1) contains everything from the local package,
 // but nothing that have been imported. When we're actually writing out export data
 // to the output files (see writeNewExport function), we run the "linker", which does
 // a few things:
 //
 // + Updates compiler extensions data (e.g., inlining cost, escape analysis results).
 //
 // + Handles re-exporting any transitive dependencies.
 //
 // + Prunes out any unnecessary details (e.g., non-inlineable functions, because any
 //   downstream importers only care about inlinable functions).
 //
 // The source files are typechecked twice, once before writing export data
 // using types2 checker, once after read export data using gc/typecheck.
 // This duplication of work will go away once we always use types2 checker,
 // we can remove the gc/typecheck pass. The reason it is still here:
 //
 // + It reduces engineering costs in maintaining a fork of typecheck
 //   (e.g., no need to backport fixes like CL 327651).
 //
 // + It makes it easier to pass toolstash -cmp.
 //
 // + Historically, we would always re-run the typechecker after import, even though
 //   we know the imported data is valid. It's not ideal, but also not causing any
 //   problem either.
 //
 // + There's still transformation that being done during gc/typecheck, like rewriting
 //   multi-valued function call, or transform ir.OINDEX -> ir.OINDEXMAP.
 //
 // Using syntax+types2 tree, which already has a complete representation of generics,
 // the unified IR has the full typed AST for doing introspection during step (1).
 // In other words, we have all necessary information to build the generic IR form
 // (see writer.captureVars for an example).
 func unified(noders []*noder) {
 	inline.NewInline = InlineCall

 	if !quirksMode() {
 		writeNewExportFunc = writeNewExport
 	} else if base.Flag.G != 0 {
 		base.Errorf("cannot use -G and -d=quirksmode together")
 	}

 	newReadImportFunc = func(data string, pkg1 *types.Pkg, ctxt *types2.Context, packages map[string]*types2.Package) (pkg2 *types2.Package, err error) {
 		pr := newPkgDecoder(pkg1.Path, data)

 		// Read package descriptors for both types2 and compiler backend.
 		readPackage(newPkgReader(pr), pkg1)
 		pkg2 = readPackage2(ctxt, packages, pr)
 		return
 	}

 	data := writePkgStub(noders)

 	// We already passed base.Flag.Lang to types2 to handle validating
 	// the user's source code. Bump it up now to the current version and
 	// re-parse, so typecheck doesn't complain if we construct IR that
 	// utilizes newer Go features.
 	base.Flag.Lang = fmt.Sprintf("go1.%d", goversion.Version)
 	types.ParseLangFlag()

 	assert(types.LocalPkg.Path == "")
 	types.LocalPkg.Height = 0 // reset so pkgReader.pkgIdx doesn't complain
 	target := typecheck.Target

 	typecheck.TypecheckAllowed = true

 	localPkgReader = newPkgReader(newPkgDecoder(types.LocalPkg.Path, data))
 	readPackage(localPkgReader, types.LocalPkg)

 	r := localPkgReader.newReader(relocMeta, privateRootIdx, syncPrivate)
 	r.pkgInit(types.LocalPkg, target)

 	// Type-check any top-level assignments. We ignore non-assignments
 	// here because other declarations are typechecked as they're
 	// constructed.
 	for i, ndecls := 0, len(target.Decls); i < ndecls; i++ {
 		switch n := target.Decls[i]; n.Op() {
 		case ir.OAS, ir.OAS2:
 			target.Decls[i] = typecheck.Stmt(n)
 		}
 	}

 	// Don't use range--bodyIdx can add closures to todoBodies.
 	for len(todoBodies) > 0 {
 		// The order we expand bodies doesn't matter, so pop from the end
 		// to reduce todoBodies reallocations if it grows further.
 		fn := todoBodies[len(todoBodies)-1]
 		todoBodies = todoBodies[:len(todoBodies)-1]

 		pri, ok := bodyReader[fn]
 		assert(ok)
 		pri.funcBody(fn)

 		// Instantiated generic function: add to Decls for typechecking
 		// and compilation.
 		if fn.OClosure == nil && len(pri.dict.targs) != 0 {
 			target.Decls = append(target.Decls, fn)
 		}
 	}
 	todoBodies = nil
 	todoBodiesDone = true

 	// Check that nothing snuck past typechecking.
 	for _, n := range target.Decls {
 		if n.Typecheck() == 0 {
 			base.FatalfAt(n.Pos(), "missed typecheck: %v", n)
 		}

 		// For functions, check that at least their first statement (if
 		// any) was typechecked too.
 		if fn, ok := n.(*ir.Func); ok && len(fn.Body) != 0 {
 			if stmt := fn.Body[0]; stmt.Typecheck() == 0 {
 				base.FatalfAt(stmt.Pos(), "missed typecheck: %v", stmt)
 			}
 		}
 	}

 	base.ExitIfErrors() // just in case
 }

 // writePkgStub type checks the given parsed source files,
 // writes an export data package stub representing them,
 // and returns the result.
 func writePkgStub(noders []*noder) string {
 	m, pkg, info := checkFiles(noders)

 	pw := newPkgWriter(m, pkg, info)

 	pw.collectDecls(noders)

 	publicRootWriter := pw.newWriter(relocMeta, syncPublic)
 	privateRootWriter := pw.newWriter(relocMeta, syncPrivate)

 	assert(publicRootWriter.idx == publicRootIdx)
 	assert(privateRootWriter.idx == privateRootIdx)

 	{
 		w := publicRootWriter
 		w.pkg(pkg)
 		w.bool(false) // has init; XXX

 		scope := pkg.Scope()
 		names := scope.Names()
 		w.len(len(names))
 		for _, name := range scope.Names() {
 			w.obj(scope.Lookup(name), nil)
 		}

 		w.sync(syncEOF)
 		w.flush()
 	}

 	{
 		w := privateRootWriter
 		w.pkgInit(noders)
 		w.flush()
 	}

 	var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
 	pw.dump(&sb)

 	// At this point, we're done with types2. Make sure the package is
 	// garbage collected.
 	freePackage(pkg)

 	return sb.String()
 }

 // freePackage ensures the given package is garbage collected.
 func freePackage(pkg *types2.Package) {
 	// The GC test below relies on a precise GC that runs finalizers as
 	// soon as objects are unreachable. Our implementation provides
 	// this, but other/older implementations may not (e.g., Go 1.4 does
 	// not because of #22350). To avoid imposing unnecessary
 	// restrictions on the GOROOT_BOOTSTRAP toolchain, we skip the test
 	// during bootstrapping.
 	if base.CompilerBootstrap {
 		return
 	}

 	// Set a finalizer on pkg so we can detect if/when it's collected.
 	done := make(chan struct{})
 	runtime.SetFinalizer(pkg, func(*types2.Package) { close(done) })

 	// Important: objects involved in cycles are not finalized, so zero
 	// out pkg to break its cycles and allow the finalizer to run.
 	*pkg = types2.Package{}

 	// It typically takes just 1 or 2 cycles to release pkg, but it
 	// doesn't hurt to try a few more times.
 	for i := 0; i < 10; i++ {
 		select {
 		case <-done:
 			return
 		default:
 			runtime.GC()
 		}
 	}

 	base.Fatalf("package never finalized")
 }

 func readPackage(pr *pkgReader, importpkg *types.Pkg) {
 	r := pr.newReader(relocMeta, publicRootIdx, syncPublic)

 	pkg := r.pkg()
 	assert(pkg == importpkg)

 	if r.bool() {
 		sym := pkg.Lookup(".inittask")
 		task := ir.NewNameAt(src.NoXPos, sym)
 		task.Class = ir.PEXTERN
 		sym.Def = task
 	}

 	for i, n := 0, r.len(); i < n; i++ {
 		r.sync(syncObject)
 		assert(!r.bool())
 		idx := r.reloc(relocObj)
 		assert(r.len() == 0)

 		path, name, code := r.p.peekObj(idx)
 		if code != objStub {
 			objReader[types.NewPkg(path, "").Lookup(name)] = pkgReaderIndex{pr, idx, nil}
 		}
 	}
 }

 func writeNewExport(out io.Writer) {
 	l := linker{
 		pw: newPkgEncoder(),

 		pkgs:  make(map[string]int),
 		decls: make(map[*types.Sym]int),
 	}

 	publicRootWriter := l.pw.newEncoder(relocMeta, syncPublic)
 	assert(publicRootWriter.idx == publicRootIdx)

 	var selfPkgIdx int

 	{
 		pr := localPkgReader
 		r := pr.newDecoder(relocMeta, publicRootIdx, syncPublic)

 		r.sync(syncPkg)
 		selfPkgIdx = l.relocIdx(pr, relocPkg, r.reloc(relocPkg))

 		r.bool() // has init

 		for i, n := 0, r.len(); i < n; i++ {
 			r.sync(syncObject)
 			assert(!r.bool())
 			idx := r.reloc(relocObj)
 			assert(r.len() == 0)

 			xpath, xname, xtag := pr.peekObj(idx)
 			assert(xpath == pr.pkgPath)
 			assert(xtag != objStub)

 			if types.IsExported(xname) {
 				l.relocIdx(pr, relocObj, idx)
 			}
 		}

 		r.sync(syncEOF)
 	}

 	{
 		var idxs []int
 		for _, idx := range l.decls {
 			idxs = append(idxs, idx)
 		}
 		sort.Ints(idxs)

 		w := publicRootWriter

 		w.sync(syncPkg)
 		w.reloc(relocPkg, selfPkgIdx)

 		w.bool(typecheck.Lookup(".inittask").Def != nil)

 		w.len(len(idxs))
 		for _, idx := range idxs {
 			w.sync(syncObject)
 			w.bool(false)
 			w.reloc(relocObj, idx)
 			w.len(0)
 		}

 		w.sync(syncEOF)
 		w.flush()
 	}

 	l.pw.dump(out)
 }
	// 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 noder

	import (
	"bytes"
	"fmt"
	"internal/goversion"
	"io"
	"runtime"
	"sort"

	"cmd/compile/internal/base"
	"cmd/compile/internal/inline"
	"cmd/compile/internal/ir"
	"cmd/compile/internal/typecheck"
	"cmd/compile/internal/types"
	"cmd/compile/internal/types2"
	"cmd/internal/src"
	)

	// localPkgReader holds the package reader used for reading the local
	// package. It exists so the unified IR linker can refer back to it
	// later.
	var localPkgReader *pkgReader

	// unified construct the local package's IR from syntax's AST.
	//
	// The pipeline contains 2 steps:
	//
	// (1) Generate package export data "stub".
	//
	// (2) Generate package IR from package export data.
	//
	// The package data "stub" at step (1) contains everything from the local package,
	// but nothing that have been imported. When we're actually writing out export data
	// to the output files (see writeNewExport function), we run the "linker", which does
	// a few things:
	//
	// + Updates compiler extensions data (e.g., inlining cost, escape analysis results).
	//
	// + Handles re-exporting any transitive dependencies.
	//
	// + Prunes out any unnecessary details (e.g., non-inlineable functions, because any
	// downstream importers only care about inlinable functions).
	//
	// The source files are typechecked twice, once before writing export data
	// using types2 checker, once after read export data using gc/typecheck.
	// This duplication of work will go away once we always use types2 checker,
	// we can remove the gc/typecheck pass. The reason it is still here:
	//
	// + It reduces engineering costs in maintaining a fork of typecheck
	// (e.g., no need to backport fixes like CL 327651).
	//
	// + It makes it easier to pass toolstash -cmp.
	//
	// + Historically, we would always re-run the typechecker after import, even though
	// we know the imported data is valid. It's not ideal, but also not causing any
	// problem either.
	//
	// + There's still transformation that being done during gc/typecheck, like rewriting
	// multi-valued function call, or transform ir.OINDEX -> ir.OINDEXMAP.
	//
	// Using syntax+types2 tree, which already has a complete representation of generics,
	// the unified IR has the full typed AST for doing introspection during step (1).
	// In other words, we have all necessary information to build the generic IR form
	// (see writer.captureVars for an example).
	func unified(noders []*noder) {
	inline.NewInline = InlineCall

	if !quirksMode() {
	writeNewExportFunc = writeNewExport
	} else if base.Flag.G != 0 {
	base.Errorf("cannot use -G and -d=quirksmode together")
	}

	newReadImportFunc = func(data string, pkg1 types.Pkg, ctxt types2.Context, packages map[string]types2.Package) (pkg2 types2.Package, err error) {
	pr := newPkgDecoder(pkg1.Path, data)

	// Read package descriptors for both types2 and compiler backend.
	readPackage(newPkgReader(pr), pkg1)
	pkg2 = readPackage2(ctxt, packages, pr)
	return
	}

	data := writePkgStub(noders)

	// We already passed base.Flag.Lang to types2 to handle validating
	// the user's source code. Bump it up now to the current version and
	// re-parse, so typecheck doesn't complain if we construct IR that
	// utilizes newer Go features.
	base.Flag.Lang = fmt.Sprintf("go1.%d", goversion.Version)
	types.ParseLangFlag()

	assert(types.LocalPkg.Path == "")
	types.LocalPkg.Height = 0 // reset so pkgReader.pkgIdx doesn't complain
	target := typecheck.Target

	typecheck.TypecheckAllowed = true

	localPkgReader = newPkgReader(newPkgDecoder(types.LocalPkg.Path, data))
	readPackage(localPkgReader, types.LocalPkg)

	r := localPkgReader.newReader(relocMeta, privateRootIdx, syncPrivate)
	r.pkgInit(types.LocalPkg, target)

	// Type-check any top-level assignments. We ignore non-assignments
	// here because other declarations are typechecked as they're
	// constructed.
	for i, ndecls := 0, len(target.Decls); i < ndecls; i++ {
	switch n := target.Decls[i]; n.Op() {
	case ir.OAS, ir.OAS2:
	target.Decls[i] = typecheck.Stmt(n)
	}
	}

	// Don't use range--bodyIdx can add closures to todoBodies.
	for len(todoBodies) > 0 {
	// The order we expand bodies doesn't matter, so pop from the end
	// to reduce todoBodies reallocations if it grows further.
	fn := todoBodies[len(todoBodies)-1]
	todoBodies = todoBodies[:len(todoBodies)-1]

	pri, ok := bodyReader[fn]
	assert(ok)
	pri.funcBody(fn)

	// Instantiated generic function: add to Decls for typechecking
	// and compilation.
	if fn.OClosure == nil && len(pri.dict.targs) != 0 {
	target.Decls = append(target.Decls, fn)
	}
	}
	todoBodies = nil
	todoBodiesDone = true

	// Check that nothing snuck past typechecking.
	for _, n := range target.Decls {
	if n.Typecheck() == 0 {
	base.FatalfAt(n.Pos(), "missed typecheck: %v", n)
	}

	// For functions, check that at least their first statement (if
	// any) was typechecked too.
	if fn, ok := n.(*ir.Func); ok && len(fn.Body) != 0 {
	if stmt := fn.Body[0]; stmt.Typecheck() == 0 {
	base.FatalfAt(stmt.Pos(), "missed typecheck: %v", stmt)
	}
	}
	}

	base.ExitIfErrors() // just in case
	}

	// writePkgStub type checks the given parsed source files,
	// writes an export data package stub representing them,
	// and returns the result.
	func writePkgStub(noders []*noder) string {
	m, pkg, info := checkFiles(noders)

	pw := newPkgWriter(m, pkg, info)

	pw.collectDecls(noders)

	publicRootWriter := pw.newWriter(relocMeta, syncPublic)
	privateRootWriter := pw.newWriter(relocMeta, syncPrivate)

	assert(publicRootWriter.idx == publicRootIdx)
	assert(privateRootWriter.idx == privateRootIdx)

	{
	w := publicRootWriter
	w.pkg(pkg)
	w.bool(false) // has init; XXX

	scope := pkg.Scope()
	names := scope.Names()
	w.len(len(names))
	for _, name := range scope.Names() {
	w.obj(scope.Lookup(name), nil)
	}

	w.sync(syncEOF)
	w.flush()
	}

	{
	w := privateRootWriter
	w.pkgInit(noders)
	w.flush()
	}

	var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
	pw.dump(&sb)

	// At this point, we're done with types2. Make sure the package is
	// garbage collected.
	freePackage(pkg)

	return sb.String()
	}

	// freePackage ensures the given package is garbage collected.
	func freePackage(pkg *types2.Package) {
	// The GC test below relies on a precise GC that runs finalizers as
	// soon as objects are unreachable. Our implementation provides
	// this, but other/older implementations may not (e.g., Go 1.4 does
	// not because of #22350). To avoid imposing unnecessary
	// restrictions on the GOROOT_BOOTSTRAP toolchain, we skip the test
	// during bootstrapping.
	if base.CompilerBootstrap {
	return
	}

	// Set a finalizer on pkg so we can detect if/when it's collected.
	done := make(chan struct{})
	runtime.SetFinalizer(pkg, func(*types2.Package) { close(done) })

	// Important: objects involved in cycles are not finalized, so zero
	// out pkg to break its cycles and allow the finalizer to run.
	*pkg = types2.Package{}

	// It typically takes just 1 or 2 cycles to release pkg, but it
	// doesn't hurt to try a few more times.
	for i := 0; i < 10; i++ {
	select {
	case <-done:
	return
	default:
	runtime.GC()
	}
	}

	base.Fatalf("package never finalized")
	}

	func readPackage(pr pkgReader, importpkg types.Pkg) {
	r := pr.newReader(relocMeta, publicRootIdx, syncPublic)

	pkg := r.pkg()
	assert(pkg == importpkg)

	if r.bool() {
	sym := pkg.Lookup(".inittask")
	task := ir.NewNameAt(src.NoXPos, sym)
	task.Class = ir.PEXTERN
	sym.Def = task
	}

	for i, n := 0, r.len(); i < n; i++ {
	r.sync(syncObject)
	assert(!r.bool())
	idx := r.reloc(relocObj)
	assert(r.len() == 0)

	path, name, code := r.p.peekObj(idx)
	if code != objStub {
	objReader[types.NewPkg(path, "").Lookup(name)] = pkgReaderIndex{pr, idx, nil}
	}
	}
	}

	func writeNewExport(out io.Writer) {
	l := linker{
	pw: newPkgEncoder(),

	pkgs: make(map[string]int),
	decls: make(map[*types.Sym]int),
	}

	publicRootWriter := l.pw.newEncoder(relocMeta, syncPublic)
	assert(publicRootWriter.idx == publicRootIdx)

	var selfPkgIdx int

	{
	pr := localPkgReader
	r := pr.newDecoder(relocMeta, publicRootIdx, syncPublic)

	r.sync(syncPkg)
	selfPkgIdx = l.relocIdx(pr, relocPkg, r.reloc(relocPkg))

	r.bool() // has init

	for i, n := 0, r.len(); i < n; i++ {
	r.sync(syncObject)
	assert(!r.bool())
	idx := r.reloc(relocObj)
	assert(r.len() == 0)

	xpath, xname, xtag := pr.peekObj(idx)
	assert(xpath == pr.pkgPath)
	assert(xtag != objStub)

	if types.IsExported(xname) {
	l.relocIdx(pr, relocObj, idx)
	}
	}

	r.sync(syncEOF)
	}

	{
	var idxs []int
	for _, idx := range l.decls {
	idxs = append(idxs, idx)
	}
	sort.Ints(idxs)

	w := publicRootWriter

	w.sync(syncPkg)
	w.reloc(relocPkg, selfPkgIdx)

	w.bool(typecheck.Lookup(".inittask").Def != nil)

	w.len(len(idxs))
	for _, idx := range idxs {
	w.sync(syncObject)
	w.bool(false)
	w.reloc(relocObj, idx)
	w.len(0)
	}

	w.sync(syncEOF)
	w.flush()
	}

	l.pw.dump(out)
	}