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[dev.link] cmd/link: drop hash maps after loading
The hash maps are used to deduplicate hashed symbols. Once we loaded all the symbols, we no longer need the hash maps. Drop them. Linking cmd/compile, name old live-B new live-B delta Loadlib_GC 13.1M ± 0% 11.3M ± 0% -13.62% (p=0.008 n=5+5) Change-Id: I4bb1f84e1111a56d9e777cd6a68f7d974b60e321 Reviewed-on: https://go-review.googlesource.com/c/go/+/245721 Reviewed-by: Jeremy Faller <jeremy@golang.org>
This commit is contained in:
Cherry Zhang
parent
cecb7a1cf3
commit
f204ca3051
2 changed files with 38 additions and 21 deletions
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@ -204,10 +204,8 @@ type Loader struct {
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objSyms []objSym // global index mapping to local index
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hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
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hashedSyms map[goobj2.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
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symsByName [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
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extStaticSyms map[nameVer]Sym // externally defined static symbols, keyed by name
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symsByName [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
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extStaticSyms map[nameVer]Sym // externally defined static symbols, keyed by name
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extReader *oReader // a dummy oReader, for external symbols
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payloadBatch []extSymPayload
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@ -285,7 +283,8 @@ type Loader struct {
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errorReporter *ErrorReporter
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npkgsyms int // number of package symbols, for accounting
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npkgsyms int // number of package symbols, for accounting
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nhashedsyms int // number of hashed symbols, for accounting
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}
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const (
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@ -332,8 +331,6 @@ func NewLoader(flags uint32, elfsetstring elfsetstringFunc, reporter *ErrorRepor
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objs: []objIdx{{}, {extReader, 0}}, // reserve index 0 for nil symbol, 1 for external symbols
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objSyms: make([]objSym, 1, 100000), // reserve index 0 for nil symbol
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extReader: extReader,
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hashed64Syms: make(map[uint64]symAndSize, 10000), // TODO: adjust preallocation sizes
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hashedSyms: make(map[goobj2.HashType]symAndSize, 20000), // TODO: adjust preallocation sizes
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symsByName: [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
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objByPkg: make(map[string]*oReader),
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outer: make(map[Sym]Sym),
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@ -388,7 +385,8 @@ func (l *Loader) addObj(pkg string, r *oReader) Sym {
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// Add a symbol from an object file, return the global index.
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// If the symbol already exist, it returns the index of that symbol.
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func (l *Loader) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj2.Sym) Sym {
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func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj2.Sym) Sym {
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l := st.l
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if l.extStart != 0 {
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panic("addSym called after external symbol is created")
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}
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@ -429,17 +427,17 @@ func (l *Loader) addSym(name string, ver int, r *oReader, li uint32, kind int, o
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if kind == hashed64Def {
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checkHash = func() (symAndSize, bool) {
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h64 = r.Hash64(li - uint32(r.ndef))
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s, existed := l.hashed64Syms[h64]
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s, existed := st.hashed64Syms[h64]
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return s, existed
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}
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addToHashMap = func(ss symAndSize) { l.hashed64Syms[h64] = ss }
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addToHashMap = func(ss symAndSize) { st.hashed64Syms[h64] = ss }
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} else {
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checkHash = func() (symAndSize, bool) {
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h = r.Hash(li - uint32(r.ndef+r.nhashed64def))
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s, existed := l.hashedSyms[*h]
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s, existed := st.hashedSyms[*h]
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return s, existed
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}
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addToHashMap = func(ss symAndSize) { l.hashedSyms[*h] = ss }
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addToHashMap = func(ss symAndSize) { st.hashedSyms[*h] = ss }
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}
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siz := osym.Siz()
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if s, existed := checkHash(); existed {
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@ -2070,7 +2068,8 @@ func (l *Loader) Preload(localSymVersion int, f *bio.Reader, lib *sym.Library, u
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}
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l.addObj(lib.Pkg, or)
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l.preloadSyms(or, pkgDef)
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st := loadState{l: l}
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st.preloadSyms(or, pkgDef)
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// The caller expects us consuming all the data
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f.MustSeek(length, os.SEEK_CUR)
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@ -2078,8 +2077,16 @@ func (l *Loader) Preload(localSymVersion int, f *bio.Reader, lib *sym.Library, u
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return r.Fingerprint()
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}
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// Holds the loader along with temporary states for loading symbols.
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type loadState struct {
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l *Loader
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hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
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hashedSyms map[goobj2.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
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}
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// Preload symbols of given kind from an object.
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func (l *Loader) preloadSyms(r *oReader, kind int) {
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func (st *loadState) preloadSyms(r *oReader, kind int) {
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l := st.l
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var start, end uint32
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switch kind {
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case pkgDef:
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@ -2121,7 +2128,7 @@ func (l *Loader) preloadSyms(r *oReader, kind int) {
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}
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v = abiToVer(osym.ABI(), r.version)
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}
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gi := l.addSym(name, v, r, i, kind, osym)
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gi := st.addSym(name, v, r, i, kind, osym)
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r.syms[i] = gi
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if osym.TopFrame() {
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l.SetAttrTopFrame(gi, true)
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@ -2152,11 +2159,20 @@ func (l *Loader) preloadSyms(r *oReader, kind int) {
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// references to external symbols (which are always named).
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func (l *Loader) LoadNonpkgSyms(arch *sys.Arch) {
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l.npkgsyms = l.NSym()
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for _, o := range l.objs[goObjStart:] {
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l.preloadSyms(o.r, hashed64Def)
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l.preloadSyms(o.r, hashedDef)
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l.preloadSyms(o.r, nonPkgDef)
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// Preallocate some space (a few hundreds KB) for some symbols.
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// As of Go 1.15, linking cmd/compile has ~8000 hashed64 symbols and
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// ~13000 hashed symbols.
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st := loadState{
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l: l,
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hashed64Syms: make(map[uint64]symAndSize, 10000),
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hashedSyms: make(map[goobj2.HashType]symAndSize, 15000),
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}
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for _, o := range l.objs[goObjStart:] {
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st.preloadSyms(o.r, hashed64Def)
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st.preloadSyms(o.r, hashedDef)
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st.preloadSyms(o.r, nonPkgDef)
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}
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l.nhashedsyms = len(st.hashed64Syms) + len(st.hashedSyms)
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for _, o := range l.objs[goObjStart:] {
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loadObjRefs(l, o.r, arch)
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}
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@ -2575,7 +2591,7 @@ func (l *Loader) Errorf(s Sym, format string, args ...interface{}) {
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func (l *Loader) Stat() string {
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s := fmt.Sprintf("%d symbols, %d reachable\n", l.NSym(), l.NReachableSym())
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s += fmt.Sprintf("\t%d package symbols, %d hashed symbols, %d non-package symbols, %d external symbols\n",
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l.npkgsyms, len(l.hashed64Syms)+len(l.hashedSyms), int(l.extStart)-l.npkgsyms-len(l.hashed64Syms)-len(l.hashedSyms), l.NSym()-int(l.extStart))
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l.npkgsyms, l.nhashedsyms, int(l.extStart)-l.npkgsyms-l.nhashedsyms, l.NSym()-int(l.extStart))
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return s
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}
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