From 83ed734df03fd11d71f06bc02906a723afaf3936 Mon Sep 17 00:00:00 2001 From: Cherry Zhang Date: Tue, 11 Aug 2020 19:57:50 -0400 Subject: [PATCH] cmd/link: pre-resolve package reference Pre-resolve package index references, so it doesn't need to do a map lookup in every cross-package symbol reference resolution. It increases the memory usage very slightly (O(# imported packages)). Change-Id: Ia76c97ac51f1c2c2d5ea7ae34853850ec69ef0a8 Reviewed-on: https://go-review.googlesource.com/c/go/+/253604 Run-TryBot: Cherry Zhang Reviewed-by: Than McIntosh TryBot-Result: Gobot Gobot --- src/cmd/link/internal/loader/loader.go | 36 ++++++++++++++++---------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go index 8fd10b0848..43a0352e0b 100644 --- a/src/cmd/link/internal/loader/loader.go +++ b/src/cmd/link/internal/loader/loader.go @@ -93,11 +93,12 @@ type oReader struct { version int // version of static symbol flags uint32 // read from object file pkgprefix string - syms []Sym // Sym's global index, indexed by local index - ndef int // cache goobj.Reader.NSym() - nhashed64def int // cache goobj.Reader.NHashed64Def() - nhasheddef int // cache goobj.Reader.NHashedDef() - objidx uint32 // index of this reader in the objs slice + syms []Sym // Sym's global index, indexed by local index + pkg []uint32 // indices of referenced package by PkgIdx (index into loader.objs array) + ndef int // cache goobj.Reader.NSym() + nhashed64def int // cache goobj.Reader.NHashed64Def() + nhasheddef int // cache goobj.Reader.NHashedDef() + objidx uint32 // index of this reader in the objs slice } // Total number of defined symbols (package symbols, hashed symbols, and @@ -219,7 +220,7 @@ type Loader struct { deferReturnTramp map[Sym]bool // whether the symbol is a trampoline of a deferreturn call - objByPkg map[string]*oReader // map package path to its Go object reader + objByPkg map[string]uint32 // map package path to the index of its Go object reader anonVersion int // most recently assigned ext static sym pseudo-version @@ -331,7 +332,7 @@ func NewLoader(flags uint32, elfsetstring elfsetstringFunc, reporter *ErrorRepor objSyms: make([]objSym, 1, 100000), // reserve index 0 for nil symbol extReader: extReader, 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), + objByPkg: make(map[string]uint32), outer: make(map[Sym]Sym), sub: make(map[Sym]Sym), dynimplib: make(map[Sym]string), @@ -370,7 +371,7 @@ func (l *Loader) addObj(pkg string, r *oReader) Sym { } pkg = objabi.PathToPrefix(pkg) // the object file contains escaped package path if _, ok := l.objByPkg[pkg]; !ok { - l.objByPkg[pkg] = r + l.objByPkg[pkg] = r.objidx } i := Sym(len(l.objSyms)) l.start[r] = i @@ -635,12 +636,7 @@ func (l *Loader) resolve(r *oReader, s goobj.SymRef) Sym { case goobj.PkgIdxSelf: rr = r default: - pkg := r.Pkg(int(p)) - var ok bool - rr, ok = l.objByPkg[pkg] - if !ok { - log.Fatalf("reference of nonexisted package %s, from %v", pkg, r.unit.Lib) - } + rr = l.objs[r.pkg[p]].r } return l.toGlobal(rr, s.SymIdx) } @@ -2195,6 +2191,18 @@ func loadObjRefs(l *Loader, r *oReader, arch *sys.Arch) { } } + // referenced packages + npkg := r.NPkg() + r.pkg = make([]uint32, npkg) + for i := 1; i < npkg; i++ { // PkgIdx 0 is a dummy invalid package + pkg := r.Pkg(i) + objidx, ok := l.objByPkg[pkg] + if !ok { + log.Fatalf("reference of nonexisted package %s, from %v", pkg, r.unit.Lib) + } + r.pkg[i] = objidx + } + // load flags of package refs for i, n := 0, r.NRefFlags(); i < n; i++ { rf := r.RefFlags(i) -- 2.48.1