attr: generate code from textflag.h (#176)

attr/attr.go

@@ -10,50 +10,7 @@ import (
 // Attribute represents TEXT or DATA flags.
 type Attribute uint16
 
-// Reference: https://github.com/golang/go/blob/aafe257390cc9048e8b5df898fabd79a9e0d4c39/src/runtime/textflag.h#L11-L37
+//go:generate go run make_textflag.go -output ztextflag.go
-//
-//	// Don't profile the marked routine. This flag is deprecated.
-//	#define NOPROF	1
-//	// It is ok for the linker to get multiple of these symbols. It will
-//	// pick one of the duplicates to use.
-//	#define DUPOK	2
-//	// Don't insert stack check preamble.
-//	#define NOSPLIT	4
-//	// Put this data in a read-only section.
-//	#define RODATA	8
-//	// This data contains no pointers.
-//	#define NOPTR	16
-//	// This is a wrapper function and should not count as disabling 'recover'.
-//	#define WRAPPER 32
-//	// This function uses its incoming context register.
-//	#define NEEDCTXT 64
-//	// Allocate a word of thread local storage and store the offset from the
-//	// thread local base to the thread local storage in this variable.
-//	#define TLSBSS	256
-//	// Do not insert instructions to allocate a stack frame for this function.
-//	// Only valid on functions that declare a frame size of 0.
-//	// TODO(mwhudson): only implemented for ppc64x at present.
-//	#define NOFRAME 512
-//	// Function can call reflect.Type.Method or reflect.Type.MethodByName.
-//	#define REFLECTMETHOD 1024
-//	// Function is the top of the call stack. Call stack unwinders should stop
-//	// at this function.
-//	#define TOPFRAME 2048
-//
-const (
-	NOPROF Attribute = 1 << iota
-	DUPOK
-	NOSPLIT
-	RODATA
-	NOPTR
-	WRAPPER
-	NEEDCTXT
-	_
-	TLSBSS
-	NOFRAME
-	REFLECTMETHOD
-	TOPFRAME
-)
 
 // Asm returns a representation of the attributes in assembly syntax. This may use macros from "textflags.h"; see ContainsTextFlags() to determine if this header is required.
 func (a Attribute) Asm() string {
@@ -86,17 +43,3 @@ func (a Attribute) split() ([]string, Attribute) {
 	}
 	return flags, rest
 }
-
-var attrname = map[Attribute]string{
-	NOPROF:        "NOPROF",
-	DUPOK:         "DUPOK",
-	NOSPLIT:       "NOSPLIT",
-	RODATA:        "RODATA",
-	NOPTR:         "NOPTR",
-	WRAPPER:       "WRAPPER",
-	NEEDCTXT:      "NEEDCTXT",
-	TLSBSS:        "TLSBSS",
-	NOFRAME:       "NOFRAME",
-	REFLECTMETHOD: "REFLECTMETHOD",
-	TOPFRAME:      "TOPFRAME",
-}

attr/make_textflag.go

@@ -0,0 +1,200 @@
+// +build ignore
+
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"go/format"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+var (
+	TextFlagPath = "src/runtime/textflag.h"
+	TextFlagName = filepath.Base(TextFlagPath)
+)
+
+var (
+	download = flag.Bool("download", false, "download new version of "+TextFlagName)
+	version  = flag.String("version", runtime.Version(), "go version to download file from")
+	textflag = flag.String("textflag", TextFlagName, "path to "+TextFlagName)
+	output   = flag.String("output", "", "path to output file")
+)
+
+func main() {
+	if err := mainerr(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func mainerr() error {
+	flag.Parse()
+
+	// Download new version, if requested.
+	if *download {
+		if err := DownloadGoSourceFile(*textflag, *version, TextFlagPath); err != nil {
+			return err
+		}
+		log.Printf("downloaded %q from version %s to %q", TextFlagPath, *version, *textflag)
+	}
+
+	// Parse text flags header.
+	fs, err := ParseFile(*textflag)
+	if err != nil {
+		return err
+	}
+
+	// Determine output.
+	w := os.Stdout
+	if *output != "" {
+		f, err := os.Create(*output)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		w = f
+	}
+
+	// Generate code and format it.
+	buf := bytes.NewBuffer(nil)
+	PrintFlagAttributes(buf, fs)
+
+	src, err := format.Source(buf.Bytes())
+	if err != nil {
+		return err
+	}
+
+	// Write output.
+	_, err = w.Write(src)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// DownloadGoSourceFile downloads a Go source file from a specific version.
+func DownloadGoSourceFile(outpath, v, srcpath string) (err error) {
+	// Download from github.
+	url := "https://github.com/golang/go/raw/" + v + "/" + srcpath
+	res, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if errc := res.Body.Close(); errc != nil && err == nil {
+			err = errc
+		}
+	}()
+
+	// Write to file.
+	buf := bytes.NewBuffer(nil)
+	fmt.Fprintf(buf, "// Code generated by downloading from %s. DO NOT EDIT.\n\n", url)
+
+	if _, err := io.Copy(buf, res.Body); err != nil {
+		return err
+	}
+
+	if err := ioutil.WriteFile(outpath, buf.Bytes(), 0644); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+type Flag struct {
+	Doc   []string
+	Name  string
+	Value int
+}
+
+// Parse text flags header format.
+func Parse(r io.Reader) ([]Flag, error) {
+	var fs []Flag
+	var doc []string
+
+	s := bufio.NewScanner(r)
+	for s.Scan() {
+		line := s.Text()
+		switch {
+		case strings.Contains(line, "TODO"):
+			// skip
+
+		case strings.HasPrefix(line, "// "):
+			doc = append(doc, strings.TrimPrefix(line, "// "))
+
+		case strings.HasPrefix(line, "#define"):
+			fields := strings.Fields(line)
+			if len(fields) != 3 || fields[0] != "#define" {
+				return nil, fmt.Errorf("unexpected line format %q", line)
+			}
+			v, err := strconv.Atoi(fields[2])
+			if err != nil {
+				return nil, err
+			}
+
+			fs = append(fs, Flag{
+				Doc:   doc,
+				Name:  fields[1],
+				Value: v,
+			})
+			doc = nil
+
+		case line == "" || line == "//":
+			doc = nil
+
+		default:
+			return nil, errors.New("unexpected format")
+		}
+	}
+
+	if err := s.Err(); err != nil {
+		return nil, err
+	}
+
+	return fs, nil
+}
+
+// ParseFile parses text flags header file.
+func ParseFile(filename string) ([]Flag, error) {
+	b, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+	return Parse(bytes.NewReader(b))
+}
+
+func PrintFlagAttributes(w io.Writer, fs []Flag) {
+	_, self, _, _ := runtime.Caller(0)
+	fmt.Fprintf(w, "// Code generated by %s. DO NOT EDIT.\n\n", filepath.Base(self))
+	fmt.Fprintf(w, "package attr\n")
+
+	// Attribute constants.
+	fmt.Fprintf(w, "\n// Attribute values defined in %s.\n", TextFlagName)
+	fmt.Fprintf(w, "const (\n")
+	for _, f := range fs {
+		for _, line := range f.Doc {
+			fmt.Fprintf(w, "\t// %s\n", line)
+		}
+		fmt.Fprintf(w, "\t%s Attribute = %d\n\n", f.Name, f.Value)
+	}
+	fmt.Fprintf(w, ")\n")
+
+	// String map.
+	fmt.Fprintf(w, "\nvar attrname = map[Attribute]string{\n")
+	for _, f := range fs {
+		fmt.Fprintf(w, "\t%s: %q,\n", f.Name, f.Name)
+	}
+	fmt.Fprintf(w, "}\n")
+}

attr/textflag.h

@@ -0,0 +1,39 @@
+// Code generated by downloading from https://github.com/golang/go/raw/go1.16.2/src/runtime/textflag.h. DO NOT EDIT.
+
+// Copyright 2013 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.
+
+// This file defines flags attached to various functions
+// and data objects. The compilers, assemblers, and linker must
+// all agree on these values.
+//
+// Keep in sync with src/cmd/internal/obj/textflag.go.
+
+// Don't profile the marked routine. This flag is deprecated.
+#define NOPROF	1
+// It is ok for the linker to get multiple of these symbols. It will
+// pick one of the duplicates to use.
+#define DUPOK	2
+// Don't insert stack check preamble.
+#define NOSPLIT	4
+// Put this data in a read-only section.
+#define RODATA	8
+// This data contains no pointers.
+#define NOPTR	16
+// This is a wrapper function and should not count as disabling 'recover'.
+#define WRAPPER 32
+// This function uses its incoming context register.
+#define NEEDCTXT 64
+// Allocate a word of thread local storage and store the offset from the
+// thread local base to the thread local storage in this variable.
+#define TLSBSS	256
+// Do not insert instructions to allocate a stack frame for this function.
+// Only valid on functions that declare a frame size of 0.
+// TODO(mwhudson): only implemented for ppc64x at present.
+#define NOFRAME 512
+// Function can call reflect.Type.Method or reflect.Type.MethodByName.
+#define REFLECTMETHOD 1024
+// Function is the top of the call stack. Call stack unwinders should stop
+// at this function.
+#define TOPFRAME 2048

attr/ztextflag.go

@@ -0,0 +1,57 @@
+// Code generated by make_textflag.go. DO NOT EDIT.
+
+package attr
+
+// Attribute values defined in textflag.h.
+const (
+	// Don't profile the marked routine. This flag is deprecated.
+	NOPROF Attribute = 1
+
+	// It is ok for the linker to get multiple of these symbols. It will
+	// pick one of the duplicates to use.
+	DUPOK Attribute = 2
+
+	// Don't insert stack check preamble.
+	NOSPLIT Attribute = 4
+
+	// Put this data in a read-only section.
+	RODATA Attribute = 8
+
+	// This data contains no pointers.
+	NOPTR Attribute = 16
+
+	// This is a wrapper function and should not count as disabling 'recover'.
+	WRAPPER Attribute = 32
+
+	// This function uses its incoming context register.
+	NEEDCTXT Attribute = 64
+
+	// Allocate a word of thread local storage and store the offset from the
+	// thread local base to the thread local storage in this variable.
+	TLSBSS Attribute = 256
+
+	// Do not insert instructions to allocate a stack frame for this function.
+	// Only valid on functions that declare a frame size of 0.
+	NOFRAME Attribute = 512
+
+	// Function can call reflect.Type.Method or reflect.Type.MethodByName.
+	REFLECTMETHOD Attribute = 1024
+
+	// Function is the top of the call stack. Call stack unwinders should stop
+	// at this function.
+	TOPFRAME Attribute = 2048
+)
+
+var attrname = map[Attribute]string{
+	NOPROF:        "NOPROF",
+	DUPOK:         "DUPOK",
+	NOSPLIT:       "NOSPLIT",
+	RODATA:        "RODATA",
+	NOPTR:         "NOPTR",
+	WRAPPER:       "WRAPPER",
+	NEEDCTXT:      "NEEDCTXT",
+	TLSBSS:        "TLSBSS",
+	NOFRAME:       "NOFRAME",
+	REFLECTMETHOD: "REFLECTMETHOD",
+	TOPFRAME:      "TOPFRAME",
+}