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// 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 (
"encoding/binary"
"fmt"
"go/constant"
"go/token"
"math/big"
"os"
"runtime"
"strings"
"cmd/compile/internal/base"
)
type pkgDecoder struct {
pkgPath string
elemEndsEnds [numRelocs]uint32
elemEnds []uint32
elemData string
}
func newPkgDecoder(pkgPath, input string) pkgDecoder {
pr := pkgDecoder{
pkgPath: pkgPath,
}
// TODO(mdempsky): Implement direct indexing of input string to
// avoid copying the position information.
r := strings.NewReader(input)
assert(binary.Read(r, binary.LittleEndian, pr.elemEndsEnds[:]) == nil)
pr.elemEnds = make([]uint32, pr.elemEndsEnds[len(pr.elemEndsEnds)-1])
assert(binary.Read(r, binary.LittleEndian, pr.elemEnds[:]) == nil)
pos, err := r.Seek(0, os.SEEK_CUR)
assert(err == nil)
pr.elemData = input[pos:]
assert(len(pr.elemData) == int(pr.elemEnds[len(pr.elemEnds)-1]))
return pr
}
func (pr *pkgDecoder) numElems(k reloc) int {
count := int(pr.elemEndsEnds[k])
if k > 0 {
count -= int(pr.elemEndsEnds[k-1])
}
return count
}
func (pr *pkgDecoder) totalElems() int {
return len(pr.elemEnds)
}
func (pr *pkgDecoder) absIdx(k reloc, idx int) int {
absIdx := idx
if k > 0 {
absIdx += int(pr.elemEndsEnds[k-1])
}
if absIdx >= int(pr.elemEndsEnds[k]) {
base.Fatalf("%v:%v is out of bounds; %v", k, idx, pr.elemEndsEnds)
}
return absIdx
}
func (pr *pkgDecoder) dataIdx(k reloc, idx int) string {
absIdx := pr.absIdx(k, idx)
var start uint32
if absIdx > 0 {
start = pr.elemEnds[absIdx-1]
}
end := pr.elemEnds[absIdx]
return pr.elemData[start:end]
}
func (pr *pkgDecoder) stringIdx(idx int) string {
return pr.dataIdx(relocString, idx)
}
func (pr *pkgDecoder) newDecoder(k reloc, idx int, marker syncMarker) decoder {
r := pr.newDecoderRaw(k, idx)
r.sync(marker)
return r
}
func (pr *pkgDecoder) newDecoderRaw(k reloc, idx int) decoder {
r := decoder{
common: pr,
k: k,
idx: idx,
}
// TODO(mdempsky) r.data.Reset(...) after #44505 is resolved.
r.data = *strings.NewReader(pr.dataIdx(k, idx))
r.sync(syncRelocs)
r.relocs = make([]relocEnt, r.len())
for i := range r.relocs {
r.sync(syncReloc)
r.relocs[i] = relocEnt{reloc(r.len()), r.len()}
}
return r
}
type decoder struct {
common *pkgDecoder
relocs []relocEnt
data strings.Reader
k reloc
idx int
}
func (r *decoder) checkErr(err error) {
if err != nil {
base.Fatalf("unexpected error: %v", err)
}
}
func (r *decoder) rawUvarint() uint64 {
x, err := binary.ReadUvarint(&r.data)
r.checkErr(err)
return x
}
func (r *decoder) rawVarint() int64 {
ux := r.rawUvarint()
// Zig-zag decode.
x := int64(ux >> 1)
if ux&1 != 0 {
x = ^x
}
return x
}
func (r *decoder) rawReloc(k reloc, idx int) int {
e := r.relocs[idx]
assert(e.kind == k)
return e.idx
}
func (r *decoder) sync(mWant syncMarker) {
if !enableSync {
return
}
pos, _ := r.data.Seek(0, os.SEEK_CUR) // TODO(mdempsky): io.SeekCurrent after #44505 is resolved
mHave := syncMarker(r.rawUvarint())
writerPCs := make([]int, r.rawUvarint())
for i := range writerPCs {
writerPCs[i] = int(r.rawUvarint())
}
if mHave == mWant {
return
}
// There's some tension here between printing:
//
// (1) full file paths that tools can recognize (e.g., so emacs
// hyperlinks the "file:line" text for easy navigation), or
//
// (2) short file paths that are easier for humans to read (e.g., by
// omitting redundant or irrelevant details, so it's easier to
// focus on the useful bits that remain).
//
// The current formatting favors the former, as it seems more
// helpful in practice. But perhaps the formatting could be improved
// to better address both concerns. For example, use relative file
// paths if they would be shorter, or rewrite file paths to contain
// "$GOROOT" (like objabi.AbsFile does) if tools can be taught how
// to reliably expand that again.
fmt.Printf("export data desync: package %q, section %v, index %v, offset %v\n", r.common.pkgPath, r.k, r.idx, pos)
fmt.Printf("\nfound %v, written at:\n", mHave)
if len(writerPCs) == 0 {
fmt.Printf("\t[stack trace unavailable; recompile package %q with -d=syncframes]\n", r.common.pkgPath)
}
for _, pc := range writerPCs {
fmt.Printf("\t%s\n", r.common.stringIdx(r.rawReloc(relocString, pc)))
}
fmt.Printf("\nexpected %v, reading at:\n", mWant)
var readerPCs [32]uintptr // TODO(mdempsky): Dynamically size?
n := runtime.Callers(2, readerPCs[:])
for _, pc := range fmtFrames(readerPCs[:n]...) {
fmt.Printf("\t%s\n", pc)
}
// We already printed a stack trace for the reader, so now we can
// simply exit. Printing a second one with panic or base.Fatalf
// would just be noise.
os.Exit(1)
}
func (r *decoder) bool() bool {
r.sync(syncBool)
x, err := r.data.ReadByte()
r.checkErr(err)
assert(x < 2)
return x != 0
}
func (r *decoder) int64() int64 {
r.sync(syncInt64)
return r.rawVarint()
}
func (r *decoder) uint64() uint64 {
r.sync(syncUint64)
return r.rawUvarint()
}
func (r *decoder) len() int { x := r.uint64(); v := int(x); assert(uint64(v) == x); return v }
func (r *decoder) int() int { x := r.int64(); v := int(x); assert(int64(v) == x); return v }
func (r *decoder) uint() uint { x := r.uint64(); v := uint(x); assert(uint64(v) == x); return v }
func (r *decoder) code(mark syncMarker) int {
r.sync(mark)
return r.len()
}
func (r *decoder) reloc(k reloc) int {
r.sync(syncUseReloc)
return r.rawReloc(k, r.len())
}
func (r *decoder) string() string {
r.sync(syncString)
return r.common.stringIdx(r.reloc(relocString))
}
func (r *decoder) strings() []string {
res := make([]string, r.len())
for i := range res {
res[i] = r.string()
}
return res
}
func (r *decoder) value() constant.Value {
r.sync(syncValue)
isComplex := r.bool()
val := r.scalar()
if isComplex {
val = constant.BinaryOp(val, token.ADD, constant.MakeImag(r.scalar()))
}
return val
}
func (r *decoder) scalar() constant.Value {
switch tag := codeVal(r.code(syncVal)); tag {
default:
panic(fmt.Sprintf("unexpected scalar tag: %v", tag))
case valBool:
return constant.MakeBool(r.bool())
case valString:
return constant.MakeString(r.string())
case valInt64:
return constant.MakeInt64(r.int64())
case valBigInt:
return constant.Make(r.bigInt())
case valBigRat:
num := r.bigInt()
denom := r.bigInt()
return constant.Make(new(big.Rat).SetFrac(num, denom))
case valBigFloat:
return constant.Make(r.bigFloat())
}
}
func (r *decoder) bigInt() *big.Int {
v := new(big.Int).SetBytes([]byte(r.string()))
if r.bool() {
v.Neg(v)
}
return v
}
func (r *decoder) bigFloat() *big.Float {
v := new(big.Float).SetPrec(512)
assert(v.UnmarshalText([]byte(r.string())) == nil)
return v
}
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