Adding upstream version 1.18.10.upstream/1.18.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 334 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/noder/unified.go b/src/cmd/compile/internal/noder/unified.go
new file mode 100644
index 0000000..ec0012d
--- /dev/null
+++ b/src/cmd/compile/internal/noder/unified.go
@@ -0,0 +1,334 @@
+// 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)
+}