[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>
diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go
index 2f4a0ef..4da77c6 100644
--- a/src/cmd/link/internal/loader/loader.go
+++ b/src/cmd/link/internal/loader/loader.go
@@ -204,10 +204,8 @@
objSyms []objSym // global index mapping to local index
- hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
- hashedSyms map[goobj2.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
- symsByName [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
- extStaticSyms map[nameVer]Sym // externally defined static symbols, keyed by name
+ symsByName [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
+ extStaticSyms map[nameVer]Sym // externally defined static symbols, keyed by name
extReader *oReader // a dummy oReader, for external symbols
payloadBatch []extSymPayload
@@ -285,7 +283,8 @@
errorReporter *ErrorReporter
- npkgsyms int // number of package symbols, for accounting
+ npkgsyms int // number of package symbols, for accounting
+ nhashedsyms int // number of hashed symbols, for accounting
}
const (
@@ -332,8 +331,6 @@
objs: []objIdx{{}, {extReader, 0}}, // reserve index 0 for nil symbol, 1 for external symbols
objSyms: make([]objSym, 1, 100000), // reserve index 0 for nil symbol
extReader: extReader,
- hashed64Syms: make(map[uint64]symAndSize, 10000), // TODO: adjust preallocation sizes
- hashedSyms: make(map[goobj2.HashType]symAndSize, 20000), // TODO: adjust preallocation sizes
symsByName: [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
objByPkg: make(map[string]*oReader),
outer: make(map[Sym]Sym),
@@ -388,7 +385,8 @@
// Add a symbol from an object file, return the global index.
// If the symbol already exist, it returns the index of that symbol.
-func (l *Loader) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj2.Sym) Sym {
+func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj2.Sym) Sym {
+ l := st.l
if l.extStart != 0 {
panic("addSym called after external symbol is created")
}
@@ -429,17 +427,17 @@
if kind == hashed64Def {
checkHash = func() (symAndSize, bool) {
h64 = r.Hash64(li - uint32(r.ndef))
- s, existed := l.hashed64Syms[h64]
+ s, existed := st.hashed64Syms[h64]
return s, existed
}
- addToHashMap = func(ss symAndSize) { l.hashed64Syms[h64] = ss }
+ addToHashMap = func(ss symAndSize) { st.hashed64Syms[h64] = ss }
} else {
checkHash = func() (symAndSize, bool) {
h = r.Hash(li - uint32(r.ndef+r.nhashed64def))
- s, existed := l.hashedSyms[*h]
+ s, existed := st.hashedSyms[*h]
return s, existed
}
- addToHashMap = func(ss symAndSize) { l.hashedSyms[*h] = ss }
+ addToHashMap = func(ss symAndSize) { st.hashedSyms[*h] = ss }
}
siz := osym.Siz()
if s, existed := checkHash(); existed {
@@ -2070,7 +2068,8 @@
}
l.addObj(lib.Pkg, or)
- l.preloadSyms(or, pkgDef)
+ st := loadState{l: l}
+ st.preloadSyms(or, pkgDef)
// The caller expects us consuming all the data
f.MustSeek(length, os.SEEK_CUR)
@@ -2078,8 +2077,16 @@
return r.Fingerprint()
}
+// Holds the loader along with temporary states for loading symbols.
+type loadState struct {
+ l *Loader
+ hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
+ hashedSyms map[goobj2.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
+}
+
// Preload symbols of given kind from an object.
-func (l *Loader) preloadSyms(r *oReader, kind int) {
+func (st *loadState) preloadSyms(r *oReader, kind int) {
+ l := st.l
var start, end uint32
switch kind {
case pkgDef:
@@ -2121,7 +2128,7 @@
}
v = abiToVer(osym.ABI(), r.version)
}
- gi := l.addSym(name, v, r, i, kind, osym)
+ gi := st.addSym(name, v, r, i, kind, osym)
r.syms[i] = gi
if osym.TopFrame() {
l.SetAttrTopFrame(gi, true)
@@ -2152,12 +2159,21 @@
// references to external symbols (which are always named).
func (l *Loader) LoadNonpkgSyms(arch *sys.Arch) {
l.npkgsyms = l.NSym()
- for _, o := range l.objs[goObjStart:] {
- l.preloadSyms(o.r, hashed64Def)
- l.preloadSyms(o.r, hashedDef)
- l.preloadSyms(o.r, nonPkgDef)
+ // Preallocate some space (a few hundreds KB) for some symbols.
+ // As of Go 1.15, linking cmd/compile has ~8000 hashed64 symbols and
+ // ~13000 hashed symbols.
+ st := loadState{
+ l: l,
+ hashed64Syms: make(map[uint64]symAndSize, 10000),
+ hashedSyms: make(map[goobj2.HashType]symAndSize, 15000),
}
for _, o := range l.objs[goObjStart:] {
+ st.preloadSyms(o.r, hashed64Def)
+ st.preloadSyms(o.r, hashedDef)
+ st.preloadSyms(o.r, nonPkgDef)
+ }
+ l.nhashedsyms = len(st.hashed64Syms) + len(st.hashedSyms)
+ for _, o := range l.objs[goObjStart:] {
loadObjRefs(l, o.r, arch)
}
l.values = make([]int64, l.NSym(), l.NSym()+1000) // +1000 make some room for external symbols
@@ -2575,7 +2591,7 @@
func (l *Loader) Stat() string {
s := fmt.Sprintf("%d symbols, %d reachable\n", l.NSym(), l.NReachableSym())
s += fmt.Sprintf("\t%d package symbols, %d hashed symbols, %d non-package symbols, %d external symbols\n",
- l.npkgsyms, len(l.hashed64Syms)+len(l.hashedSyms), int(l.extStart)-l.npkgsyms-len(l.hashed64Syms)-len(l.hashedSyms), l.NSym()-int(l.extStart))
+ l.npkgsyms, l.nhashedsyms, int(l.extStart)-l.npkgsyms-l.nhashedsyms, l.NSym()-int(l.extStart))
return s
}
diff --git a/src/cmd/link/internal/loader/loader_test.go b/src/cmd/link/internal/loader/loader_test.go
index 70e0986..af66752 100644
--- a/src/cmd/link/internal/loader/loader_test.go
+++ b/src/cmd/link/internal/loader/loader_test.go
@@ -21,7 +21,8 @@
// data or relocations).
func addDummyObjSym(t *testing.T, ldr *Loader, or *oReader, name string) Sym {
idx := uint32(len(ldr.objSyms))
- return ldr.addSym(name, 0, or, idx, nonPkgDef, &goobj2.Sym{})
+ st := loadState{l: ldr}
+ return st.addSym(name, 0, or, idx, nonPkgDef, &goobj2.Sym{})
}
func mkLoader() *Loader {
