cmd/link: split "bag of Symbols" functionality out of Link

Mechanical refactorings to follow.

Change-Id: I9b98e69a58c3cba7c7d1d3e3f600d4ed99d4fce2
Reviewed-on: https://go-review.googlesource.com/29342
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/link/internal/ld/link.go

@@ -173,27 +173,22 @@ type Shlib struct {
 // Link holds the context for writing object code from a compiler
 // or for reading that input into the linker.
 type Link struct {
+	Symbols
+
 	Arch      *sys.Arch
 	Debugvlog int
 	Bso       *bufio.Writer
 
 	Loaded bool // set after all inputs have been loaded as symbols
 
-	// Symbol lookup based on name and indexed by version.
-	Hash []map[string]*Symbol
-
-	Allsym    []*Symbol
-	Tlsg      *Symbol
-	Libdir    []string
-	Library   []*Library
-	Shlibs    []Shlib
-	Tlsoffset int
-
-	Version     int
-	Textp       []*Symbol
-	Filesyms    []*Symbol
-	Moduledata  *Symbol
-	SymbolBatch []Symbol
+	Tlsg       *Symbol
+	Libdir     []string
+	Library    []*Library
+	Shlibs     []Shlib
+	Tlsoffset  int
+	Textp      []*Symbol
+	Filesyms   []*Symbol
+	Moduledata *Symbol
 }
 
 // The smallest possible offset from the hardware stack pointer to a local
@@ -213,11 +208,6 @@ func (ctxt *Link) FixedFrameSize() int64 {
 	}
 }
 
-func (l *Link) IncVersion() {
-	l.Version++
-	l.Hash = append(l.Hash, make(map[string]*Symbol))
-}
-
 func (l *Link) Logf(format string, args ...interface{}) {
 	fmt.Fprintf(l.Bso, format, args...)
 	l.Bso.Flush()

src/cmd/link/internal/ld/sym.go

@@ -39,13 +39,15 @@ import (
 
 func linknew(arch *sys.Arch) *Link {
 	ctxt := &Link{
-		Hash: []map[string]*Symbol{
-			// preallocate about 2mb for hash of
-			// non static symbols
-			make(map[string]*Symbol, 100000),
+		Symbols: Symbols{
+			hash: []map[string]*Symbol{
+				// preallocate about 2mb for hash of
+				// non static symbols
+				make(map[string]*Symbol, 100000),
+			},
+			Allsym: make([]*Symbol, 0, 100000),
 		},
-		Allsym: make([]*Symbol, 0, 100000),
-		Arch:   arch,
+		Arch: arch,
 	}
 
 	if obj.GOARCH != arch.Name {
@@ -132,36 +134,14 @@ func (ctxt *Link) computeTLSOffset() {
 }
 
 func linknewsym(ctxt *Link, name string, v int) *Symbol {
-	batch := ctxt.SymbolBatch
-	if len(batch) == 0 {
-		batch = make([]Symbol, 1000)
-	}
-	s := &batch[0]
-	ctxt.SymbolBatch = batch[1:]
-
-	s.Dynid = -1
-	s.Plt = -1
-	s.Got = -1
-	s.Name = name
-	s.Version = int16(v)
-	ctxt.Allsym = append(ctxt.Allsym, s)
-
-	return s
+	return ctxt.newsym(name, v)
 }
 
 func Linklookup(ctxt *Link, name string, v int) *Symbol {
-	m := ctxt.Hash[v]
-	s := m[name]
-	if s != nil {
-		return s
-	}
-	s = linknewsym(ctxt, name, v)
-	s.Extname = s.Name
-	m[name] = s
-	return s
+	return ctxt.Lookup(name, v)
 }
 
 // read-only lookup
 func Linkrlookup(ctxt *Link, name string, v int) *Symbol {
-	return ctxt.Hash[v][name]
+	return ctxt.ROLookup(name, v)
 }

src/cmd/link/internal/ld/symbols.go

+// Derived from Inferno utils/6l/l.h and related files.
+// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/l.h
+//
+//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
+//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
+//	Portions Copyright © 1997-1999 Vita Nuova Limited
+//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
+//	Portions Copyright © 2004,2006 Bruce Ellis
+//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
+//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
+//	Portions Copyright © 2009 The Go Authors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package ld
+
+type Symbols struct {
+	symbolBatch []Symbol
+
+	// Symbol lookup based on name and indexed by version.
+	hash []map[string]*Symbol
+
+	Allsym []*Symbol
+
+	Version int
+}
+
+func (syms *Symbols) newsym(name string, v int) *Symbol {
+	batch := syms.symbolBatch
+	if len(batch) == 0 {
+		batch = make([]Symbol, 1000)
+	}
+	s := &batch[0]
+	syms.symbolBatch = batch[1:]
+
+	s.Dynid = -1
+	s.Plt = -1
+	s.Got = -1
+	s.Name = name
+	s.Version = int16(v)
+	syms.Allsym = append(syms.Allsym, s)
+
+	return s
+}
+
+// Look up the symbol with the given name and version, creating the
+// symbol if it is not found.
+func (syms *Symbols) Lookup(name string, v int) *Symbol {
+	m := syms.hash[v]
+	s := m[name]
+	if s != nil {
+		return s
+	}
+	s = syms.newsym(name, v)
+	s.Extname = s.Name
+	m[name] = s
+	return s
+}
+
+// Look up the symbol with the given name and version, returning nil
+// if it is not found.
+func (syms *Symbols) ROLookup(name string, v int) *Symbol {
+	return syms.hash[v][name]
+}
+
+// Allocate a new version (i.e. symbol namespace).
+//
+// TODO(mwhudson): This would feel more natural if it returned the new
+// version (or if we dropped Symbols.Version entirely and just
+// returned len(syms.hash))
+func (syms *Symbols) IncVersion() {
+	syms.Version++
+	syms.hash = append(syms.hash, make(map[string]*Symbol))
+}