1 files changed, 334 insertions, 0 deletions
diff --git a/src/cmd/dist/buildtool.go b/src/cmd/dist/buildtool.go
new file mode 100644
index 0000000..3232896
--- /dev/null
+++ b/src/cmd/dist/buildtool.go
@@ -0,0 +1,334 @@
+// Copyright 2015 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.
+
+// Build toolchain using Go bootstrap version.
+//
+// The general strategy is to copy the source files we need into
+// a new GOPATH workspace, adjust import paths appropriately,
+// invoke the Go bootstrap toolchains go command to build those sources,
+// and then copy the binaries back.
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+// bootstrapDirs is a list of directories holding code that must be
+// compiled with the Go bootstrap toolchain to produce the bootstrapTargets.
+// All directories in this list are relative to and must be below $GOROOT/src.
+//
+// The list has two kinds of entries: names beginning with cmd/ with
+// no other slashes, which are commands, and other paths, which are packages
+// supporting the commands. Packages in the standard library can be listed
+// if a newer copy needs to be substituted for the Go bootstrap copy when used
+// by the command packages. Paths ending with /... automatically
+// include all packages within subdirectories as well.
+// These will be imported during bootstrap as bootstrap/name, like bootstrap/math/big.
+var bootstrapDirs = []string{
+	"cmp",
+	"cmd/asm",
+	"cmd/asm/internal/...",
+	"cmd/cgo",
+	"cmd/compile",
+	"cmd/compile/internal/...",
+	"cmd/internal/archive",
+	"cmd/internal/bio",
+	"cmd/internal/codesign",
+	"cmd/internal/dwarf",
+	"cmd/internal/edit",
+	"cmd/internal/gcprog",
+	"cmd/internal/goobj",
+	"cmd/internal/notsha256",
+	"cmd/internal/obj/...",
+	"cmd/internal/objabi",
+	"cmd/internal/pkgpath",
+	"cmd/internal/quoted",
+	"cmd/internal/src",
+	"cmd/internal/sys",
+	"cmd/link",
+	"cmd/link/internal/...",
+	"compress/flate",
+	"compress/zlib",
+	"container/heap",
+	"debug/dwarf",
+	"debug/elf",
+	"debug/macho",
+	"debug/pe",
+	"go/build/constraint",
+	"go/constant",
+	"go/version",
+	"internal/abi",
+	"internal/coverage",
+	"cmd/internal/cov/covcmd",
+	"internal/bisect",
+	"internal/buildcfg",
+	"internal/goarch",
+	"internal/godebugs",
+	"internal/goexperiment",
+	"internal/goroot",
+	"internal/gover",
+	"internal/goversion",
+	// internal/lazyregexp is provided by Go 1.17, which permits it to
+	// be imported by other packages in this list, but is not provided
+	// by the Go 1.17 version of gccgo. It's on this list only to
+	// support gccgo, and can be removed if we require gccgo 14 or later.
+	"internal/lazyregexp",
+	"internal/pkgbits",
+	"internal/platform",
+	"internal/profile",
+	"internal/race",
+	"internal/saferio",
+	"internal/syscall/unix",
+	"internal/types/errors",
+	"internal/unsafeheader",
+	"internal/xcoff",
+	"internal/zstd",
+	"math/bits",
+	"sort",
+}
+
+// File prefixes that are ignored by go/build anyway, and cause
+// problems with editor generated temporary files (#18931).
+var ignorePrefixes = []string{
+	".",
+	"_",
+	"#",
+}
+
+// File suffixes that use build tags introduced since Go 1.17.
+// These must not be copied into the bootstrap build directory.
+// Also ignore test files.
+var ignoreSuffixes = []string{
+	"_test.s",
+	"_test.go",
+	// Skip PGO profile. No need to build toolchain1 compiler
+	// with PGO. And as it is not a text file the import path
+	// rewrite will break it.
+	".pgo",
+}
+
+var tryDirs = []string{
+	"sdk/go1.17",
+	"go1.17",
+}
+
+func bootstrapBuildTools() {
+	goroot_bootstrap := os.Getenv("GOROOT_BOOTSTRAP")
+	if goroot_bootstrap == "" {
+		home := os.Getenv("HOME")
+		goroot_bootstrap = pathf("%s/go1.4", home)
+		for _, d := range tryDirs {
+			if p := pathf("%s/%s", home, d); isdir(p) {
+				goroot_bootstrap = p
+			}
+		}
+	}
+	xprintf("Building Go toolchain1 using %s.\n", goroot_bootstrap)
+
+	mkbuildcfg(pathf("%s/src/internal/buildcfg/zbootstrap.go", goroot))
+	mkobjabi(pathf("%s/src/cmd/internal/objabi/zbootstrap.go", goroot))
+
+	// Use $GOROOT/pkg/bootstrap as the bootstrap workspace root.
+	// We use a subdirectory of $GOROOT/pkg because that's the
+	// space within $GOROOT where we store all generated objects.
+	// We could use a temporary directory outside $GOROOT instead,
+	// but it is easier to debug on failure if the files are in a known location.
+	workspace := pathf("%s/pkg/bootstrap", goroot)
+	xremoveall(workspace)
+	xatexit(func() { xremoveall(workspace) })
+	base := pathf("%s/src/bootstrap", workspace)
+	xmkdirall(base)
+
+	// Copy source code into $GOROOT/pkg/bootstrap and rewrite import paths.
+	writefile("module bootstrap\ngo 1.20\n", pathf("%s/%s", base, "go.mod"), 0)
+	for _, dir := range bootstrapDirs {
+		recurse := strings.HasSuffix(dir, "/...")
+		dir = strings.TrimSuffix(dir, "/...")
+		filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				fatalf("walking bootstrap dirs failed: %v: %v", path, err)
+			}
+
+			name := filepath.Base(path)
+			src := pathf("%s/src/%s", goroot, path)
+			dst := pathf("%s/%s", base, path)
+
+			if info.IsDir() {
+				if !recurse && path != dir || name == "testdata" {
+					return filepath.SkipDir
+				}
+
+				xmkdirall(dst)
+				if path == "cmd/cgo" {
+					// Write to src because we need the file both for bootstrap
+					// and for later in the main build.
+					mkzdefaultcc("", pathf("%s/zdefaultcc.go", src))
+					mkzdefaultcc("", pathf("%s/zdefaultcc.go", dst))
+				}
+				return nil
+			}
+
+			for _, pre := range ignorePrefixes {
+				if strings.HasPrefix(name, pre) {
+					return nil
+				}
+			}
+			for _, suf := range ignoreSuffixes {
+				if strings.HasSuffix(name, suf) {
+					return nil
+				}
+			}
+
+			text := bootstrapRewriteFile(src)
+			writefile(text, dst, 0)
+			return nil
+		})
+	}
+
+	// Set up environment for invoking Go bootstrap toolchains go command.
+	// GOROOT points at Go bootstrap GOROOT,
+	// GOPATH points at our bootstrap workspace,
+	// GOBIN is empty, so that binaries are installed to GOPATH/bin,
+	// and GOOS, GOHOSTOS, GOARCH, and GOHOSTOS are empty,
+	// so that Go bootstrap toolchain builds whatever kind of binary it knows how to build.
+	// Restore GOROOT, GOPATH, and GOBIN when done.
+	// Don't bother with GOOS, GOHOSTOS, GOARCH, and GOHOSTARCH,
+	// because setup will take care of those when bootstrapBuildTools returns.
+
+	defer os.Setenv("GOROOT", os.Getenv("GOROOT"))
+	os.Setenv("GOROOT", goroot_bootstrap)
+
+	defer os.Setenv("GOPATH", os.Getenv("GOPATH"))
+	os.Setenv("GOPATH", workspace)
+
+	defer os.Setenv("GOBIN", os.Getenv("GOBIN"))
+	os.Setenv("GOBIN", "")
+
+	os.Setenv("GOOS", "")
+	os.Setenv("GOHOSTOS", "")
+	os.Setenv("GOARCH", "")
+	os.Setenv("GOHOSTARCH", "")
+
+	// Run Go bootstrap to build binaries.
+	// Use the math_big_pure_go build tag to disable the assembly in math/big
+	// which may contain unsupported instructions.
+	// Use the purego build tag to disable other assembly code,
+	// such as in cmd/internal/notsha256.
+	cmd := []string{
+		pathf("%s/bin/go", goroot_bootstrap),
+		"install",
+		"-tags=math_big_pure_go compiler_bootstrap purego",
+	}
+	if vflag > 0 {
+		cmd = append(cmd, "-v")
+	}
+	if tool := os.Getenv("GOBOOTSTRAP_TOOLEXEC"); tool != "" {
+		cmd = append(cmd, "-toolexec="+tool)
+	}
+	cmd = append(cmd, "bootstrap/cmd/...")
+	run(base, ShowOutput|CheckExit, cmd...)
+
+	// Copy binaries into tool binary directory.
+	for _, name := range bootstrapDirs {
+		if !strings.HasPrefix(name, "cmd/") {
+			continue
+		}
+		name = name[len("cmd/"):]
+		if !strings.Contains(name, "/") {
+			copyfile(pathf("%s/%s%s", tooldir, name, exe), pathf("%s/bin/%s%s", workspace, name, exe), writeExec)
+		}
+	}
+
+	if vflag > 0 {
+		xprintf("\n")
+	}
+}
+
+var ssaRewriteFileSubstring = filepath.FromSlash("src/cmd/compile/internal/ssa/rewrite")
+
+// isUnneededSSARewriteFile reports whether srcFile is a
+// src/cmd/compile/internal/ssa/rewriteARCHNAME.go file for an
+// architecture that isn't for the given GOARCH.
+//
+// When unneeded is true archCaps is the rewrite base filename without
+// the "rewrite" prefix or ".go" suffix: AMD64, 386, ARM, ARM64, etc.
+func isUnneededSSARewriteFile(srcFile, goArch string) (archCaps string, unneeded bool) {
+	if !strings.Contains(srcFile, ssaRewriteFileSubstring) {
+		return "", false
+	}
+	fileArch := strings.TrimSuffix(strings.TrimPrefix(filepath.Base(srcFile), "rewrite"), ".go")
+	if fileArch == "" {
+		return "", false
+	}
+	b := fileArch[0]
+	if b == '_' || ('a' <= b && b <= 'z') {
+		return "", false
+	}
+	archCaps = fileArch
+	fileArch = strings.ToLower(fileArch)
+	fileArch = strings.TrimSuffix(fileArch, "splitload")
+	fileArch = strings.TrimSuffix(fileArch, "latelower")
+	if fileArch == goArch {
+		return "", false
+	}
+	if fileArch == strings.TrimSuffix(goArch, "le") {
+		return "", false
+	}
+	return archCaps, true
+}
+
+func bootstrapRewriteFile(srcFile string) string {
+	// During bootstrap, generate dummy rewrite files for
+	// irrelevant architectures. We only need to build a bootstrap
+	// binary that works for the current gohostarch.
+	// This saves 6+ seconds of bootstrap.
+	if archCaps, ok := isUnneededSSARewriteFile(srcFile, gohostarch); ok {
+		return fmt.Sprintf(`%spackage ssa
+
+func rewriteValue%s(v *Value) bool { panic("unused during bootstrap") }
+func rewriteBlock%s(b *Block) bool { panic("unused during bootstrap") }
+`, generatedHeader, archCaps, archCaps)
+	}
+
+	return bootstrapFixImports(srcFile)
+}
+
+func bootstrapFixImports(srcFile string) string {
+	text := readfile(srcFile)
+	if !strings.Contains(srcFile, "/cmd/") && !strings.Contains(srcFile, `\cmd\`) {
+		text = regexp.MustCompile(`\bany\b`).ReplaceAllString(text, "interface{}")
+	}
+	lines := strings.SplitAfter(text, "\n")
+	inBlock := false
+	for i, line := range lines {
+		if strings.HasPrefix(line, "import (") {
+			inBlock = true
+			continue
+		}
+		if inBlock && strings.HasPrefix(line, ")") {
+			inBlock = false
+			continue
+		}
+		if strings.HasPrefix(line, `import "`) || strings.HasPrefix(line, `import . "`) ||
+			inBlock && (strings.HasPrefix(line, "\t\"") || strings.HasPrefix(line, "\t. \"") || strings.HasPrefix(line, "\texec \"") || strings.HasPrefix(line, "\trtabi \"")) {
+			line = strings.Replace(line, `"cmd/`, `"bootstrap/cmd/`, -1)
+			for _, dir := range bootstrapDirs {
+				if strings.HasPrefix(dir, "cmd/") {
+					continue
+				}
+				line = strings.Replace(line, `"`+dir+`"`, `"bootstrap/`+dir+`"`, -1)
+			}
+			lines[i] = line
+		}
+	}
+
+	lines[0] = generatedHeader + "// This is a bootstrap copy of " + srcFile + "\n\n//line " + srcFile + ":1\n" + lines[0]
+
+	return strings.Join(lines, "")
+}