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cmd/compile: improve efficiency of binary export position encoding

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Use -64 instead of 0 as the magic "new file"
line delta, since it is much less common.

Use a new path encoding that breaks up paths
into /-separated components, allowing
reuse of the component strings, and making
many re-used paths a single byte to encode.

Bump the export version to 5.

Fixes #20080

name        old export-bytes  new export-bytes  delta
Template          19.1k ± 0%        17.4k ± 0%  -8.74%  (p=0.008 n=5+5)
Unicode           4.47k ± 0%        4.42k ± 0%  -0.96%  (p=0.008 n=5+5)
GoTypes           29.9k ± 0%        27.6k ± 0%  -7.41%  (p=0.008 n=5+5)
Compiler          71.4k ± 0%        65.4k ± 0%  -8.45%  (p=0.008 n=5+5)
SSA               67.8k ± 0%        65.6k ± 0%  -3.38%  (p=0.008 n=5+5)
Flate             4.99k ± 0%        4.79k ± 0%  -3.91%  (p=0.008 n=5+5)
GoParser          8.77k ± 0%        7.97k ± 0%  -9.14%  (p=0.008 n=5+5)
Reflect           6.27k ± 0%        6.13k ± 0%  -2.22%  (p=0.008 n=5+5)
Tar               9.46k ± 0%        8.82k ± 0%  -6.69%  (p=0.008 n=5+5)
XML               16.0k ± 0%        14.9k ± 0%  -6.69%  (p=0.008 n=5+5)
[Geo mean]        14.8k             14.0k       -5.80%

Change-Id: Iea0c8c62e61dbab3cfd14ee121e34845c85f00d2
Reviewed-on: https://go-review.googlesource.com/41619
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2017-04-24 06:06:14 -07:00
parent 5101231425
commit a6b16e0024
3 changed files with 155 additions and 70 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
src/cmd/compile/internal/gc/bexport.go
View File

@ -135,12 +135,13 @@ import (
const debugFormat = false // default: false
// Current export format version. Increase with each format change.
// 5: improved position encoding efficiency (issue 20080, CL 41619)
// 4: type name objects support type aliases, uses aliasTag
// 3: Go1.8 encoding (same as version 2, aliasTag defined but never used)
// 2: removed unused bool in ODCL export (compiler only)
// 1: header format change (more regular), export package for _ struct fields
// 0: Go1.7 encoding
const exportVersion = 4
const exportVersion = 5
// exportInlined enables the export of inlined function bodies and related
// dependencies. The compiler should work w/o any loss of functionality with
@ -164,10 +165,11 @@ type exporter struct {
out *bufio.Writer
// object -> index maps, indexed in order of serialization
strIndex map[string]int
pkgIndex map[*types.Pkg]int
typIndex map[*types.Type]int
funcList []*Func
strIndex map[string]int
pathIndex map[string]int
pkgIndex map[*types.Pkg]int
typIndex map[*types.Type]int
funcList []*Func
// position encoding
posInfoFormat bool
@ -185,6 +187,7 @@ func export(out *bufio.Writer, trace bool) int {
p := exporter{
out: out,
strIndex: map[string]int{"": 0}, // empty string is mapped to 0
pathIndex: map[string]int{"": 0}, // empty path is mapped to 0
pkgIndex: make(map[*types.Pkg]int),
typIndex: make(map[*types.Type]int),
posInfoFormat: true,
@ -416,7 +419,7 @@ func (p *exporter) pkg(pkg *types.Pkg) {
p.tag(packageTag)
p.string(pkg.Name)
p.string(pkg.Path)
p.path(pkg.Path)
}
func unidealType(typ *types.Type, val Val) *types.Type {
@ -515,6 +518,11 @@ func (p *exporter) obj(sym *types.Sym) {
}
}
// deltaNewFile is a magic line delta offset indicating a new file.
// We use -64 because it is rare; see issue 20080 and CL 41619.
// -64 is the smallest int that fits in a single byte as a varint.
const deltaNewFile = -64
func (p *exporter) pos(n *Node) {
if !p.posInfoFormat {
return
@ -523,30 +531,39 @@ func (p *exporter) pos(n *Node) {
file, line := fileLine(n)
if file == p.prevFile {
// common case: write line delta
// delta == 0 means different file or no line change
// delta == deltaNewFile means different file
// if the actual line delta is deltaNewFile,
// follow up with a negative int to indicate that.
// only non-negative ints can follow deltaNewFile
// when writing a new file.
delta := line - p.prevLine
p.int(delta)
if delta == 0 {
if delta == deltaNewFile {
p.int(-1) // -1 means no file change
}
} else {
// different file
p.int(0)
// Encode filename as length of common prefix with previous
// filename, followed by (possibly empty) suffix. Filenames
// frequently share path prefixes, so this can save a lot
// of space and make export data size less dependent on file
// path length. The suffix is unlikely to be empty because
// file names tend to end in ".go".
n := commonPrefixLen(p.prevFile, file)
p.int(n) // n >= 0
p.string(file[n:]) // write suffix only
p.int(deltaNewFile)
p.int(line) // line >= 0
p.path(file)
p.prevFile = file
p.int(line)
}
p.prevLine = line
}
func (p *exporter) path(s string) {
if i, ok := p.pathIndex[s]; ok {
p.index('p', i) // i >= 0
return
}
p.pathIndex[s] = len(p.pathIndex)
c := strings.Split(s, "/")
p.int(-len(c)) // -len(c) < 0
for _, x := range c {
p.string(x)
}
}
func fileLine(n *Node) (file string, line int) {
if n != nil {
pos := Ctxt.PosTable.Pos(n.Pos)
@ -556,18 +573,6 @@ func fileLine(n *Node) (file string, line int) {
return
}
func commonPrefixLen(a, b string) int {
if len(a) > len(b) {
a, b = b, a
}
// len(a) <= len(b)
i := 0
for i < len(a) && a[i] == b[i] {
i++
}
return i
}
func isInlineable(n *Node) bool {
if exportInlined && n != nil && n.Func != nil && n.Func.Inl.Len() != 0 {
// when lazily typechecking inlined bodies, some re-exported ones may not have been typechecked yet.

68
src/cmd/compile/internal/gc/bimport.go
View File

@ -32,6 +32,7 @@ type importer struct {
// object lists, in order of deserialization
strList []string
pathList []string
pkgList []*types.Pkg
typList []*types.Type
funcList []*Node // nil entry means already declared
@ -57,10 +58,11 @@ func Import(imp *types.Pkg, in *bufio.Reader) {
defer func() { inimport = false }()
p := importer{
in: in,
imp: imp,
version: -1, // unknown version
strList: []string{""}, // empty string is mapped to 0
in: in,
imp: imp,
version: -1, // unknown version
strList: []string{""}, // empty string is mapped to 0
pathList: []string{""}, // empty path is mapped to 0
}
// read version info
@ -94,10 +96,10 @@ func Import(imp *types.Pkg, in *bufio.Reader) {
// read version specific flags - extend as necessary
switch p.version {
// case 5:
// case 6:
// ...
// fallthrough
case 4, 3, 2, 1:
case 5, 4, 3, 2, 1:
p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
p.trackAllTypes = p.bool()
p.posInfoFormat = p.bool()
@ -270,7 +272,12 @@ func (p *importer) pkg() *types.Pkg {
// read package data
name := p.string()
path := p.string()
var path string
if p.version >= 5 {
path = p.path()
} else {
path = p.string()
}
// we should never see an empty package name
if name == "" {
@ -382,14 +389,27 @@ func (p *importer) pos() src.XPos {
file := p.prevFile
line := p.prevLine
if delta := p.int(); delta != 0 {
// line changed
line += delta
} else if n := p.int(); n >= 0 {
// file changed
file = p.prevFile[:n] + p.string()
delta := p.int()
line += delta
if p.version >= 5 {
if delta == deltaNewFile {
if n := p.int(); n >= 0 {
// file changed
file = p.path()
line = n
}
}
} else {
if delta == 0 {
if n := p.int(); n >= 0 {
// file changed
file = p.prevFile[:n] + p.string()
line = p.int()
}
}
}
if file != p.prevFile {
p.prevFile = file
line = p.int()
p.posBase = src.NewFileBase(file, file)
}
p.prevLine = line
@ -399,6 +419,26 @@ func (p *importer) pos() src.XPos {
return xpos
}
func (p *importer) path() string {
if p.debugFormat {
p.marker('p')
}
// if the path was seen before, i is its index (>= 0)
// (the empty string is at index 0)
i := p.rawInt64()
if i >= 0 {
return p.pathList[i]
}
// otherwise, i is the negative path length (< 0)
a := make([]string, -i)
for n := range a {
a[n] = p.string()
}
s := strings.Join(a, "/")
p.pathList = append(p.pathList, s)
return s
}
func (p *importer) newtyp(etype types.EType) *types.Type {
t := types.New(etype)
if p.trackAllTypes {

90
src/go/internal/gcimporter/bimport.go
View File

@ -19,14 +19,15 @@ import (
)
type importer struct {
imports map[string]*types.Package
data []byte
path string
buf []byte // for reading strings
version int // export format version
imports map[string]*types.Package
data []byte
importpath string
buf []byte // for reading strings
version int // export format version
// object lists
strList []string // in order of appearance
pathList []string // in order of appearance
pkgList []*types.Package // in order of appearance
typList []types.Type // in order of appearance
interfaceList []*types.Interface // for delayed completion only
@ -60,13 +61,14 @@ func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []
}()
p := importer{
imports: imports,
data: data,
path: path,
version: -1, // unknown version
strList: []string{""}, // empty string is mapped to 0
fset: fset,
files: make(map[string]*token.File),
imports: imports,
data: data,
importpath: path,
version: -1, // unknown version
strList: []string{""}, // empty string is mapped to 0
pathList: []string{""}, // empty string is mapped to 0
fset: fset,
files: make(map[string]*token.File),
}
// read version info
@ -100,10 +102,10 @@ func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []
// read version specific flags - extend as necessary
switch p.version {
// case 5:
// case 6:
// ...
// fallthrough
case 4, 3, 2, 1:
case 5, 4, 3, 2, 1:
p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
p.trackAllTypes = p.int() != 0
p.posInfoFormat = p.int() != 0
@ -169,12 +171,17 @@ func (p *importer) pkg() *types.Package {
// otherwise, i is the package tag (< 0)
if i != packageTag {
errorf("unexpected package tag %d", i)
errorf("unexpected package tag %d version %d", i, p.version)
}
// read package data
name := p.string()
path := p.string()
var path string
if p.version >= 5 {
path = p.path()
} else {
path = p.string()
}
// we should never see an empty package name
if name == "" {
@ -189,7 +196,7 @@ func (p *importer) pkg() *types.Package {
// if the package was imported before, use that one; otherwise create a new one
if path == "" {
path = p.path
path = p.importpath
}
pkg := p.imports[path]
if pkg == nil {
@ -283,6 +290,8 @@ func (p *importer) obj(tag int) {
}
}
const deltaNewFile = -64 // see cmd/compile/internal/gc/bexport.go
func (p *importer) pos() token.Pos {
if !p.posInfoFormat {
return token.NoPos
@ -290,15 +299,26 @@ func (p *importer) pos() token.Pos {
file := p.prevFile
line := p.prevLine
if delta := p.int(); delta != 0 {
// line changed
line += delta
} else if n := p.int(); n >= 0 {
// file changed
file = p.prevFile[:n] + p.string()
p.prevFile = file
line = p.int()
delta := p.int()
line += delta
if p.version >= 5 {
if delta == deltaNewFile {
if n := p.int(); n >= 0 {
// file changed
file = p.path()
line = n
}
}
} else {
if delta == 0 {
if n := p.int(); n >= 0 {
// file changed
file = p.prevFile[:n] + p.string()
line = p.int()
}
}
}
p.prevFile = file
p.prevLine = line
// Synthesize a token.Pos
@ -776,6 +796,26 @@ func (p *importer) int64() int64 {
return p.rawInt64()
}
func (p *importer) path() string {
if p.debugFormat {
p.marker('p')
}
// if the path was seen before, i is its index (>= 0)
// (the empty string is at index 0)
i := p.rawInt64()
if i >= 0 {
return p.pathList[i]
}
// otherwise, i is the negative path length (< 0)
a := make([]string, -i)
for n := range a {
a[n] = p.string()
}
s := strings.Join(a, "/")
p.pathList = append(p.pathList, s)
return s
}
func (p *importer) string() string {
if p.debugFormat {
p.marker('s')