github.com/yukk001/go1.10.8@v0.0.0-20190813125351-6df2d3982e20/src/cmd/link/internal/sym/symbols.go (about)

     1  // Derived from Inferno utils/6l/l.h and related files.
     2  // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/l.h
     3  //
     4  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     5  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
     6  //	Portions Copyright © 1997-1999 Vita Nuova Limited
     7  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
     8  //	Portions Copyright © 2004,2006 Bruce Ellis
     9  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    10  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    11  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    12  //
    13  // Permission is hereby granted, free of charge, to any person obtaining a copy
    14  // of this software and associated documentation files (the "Software"), to deal
    15  // in the Software without restriction, including without limitation the rights
    16  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    17  // copies of the Software, and to permit persons to whom the Software is
    18  // furnished to do so, subject to the following conditions:
    19  //
    20  // The above copyright notice and this permission notice shall be included in
    21  // all copies or substantial portions of the Software.
    22  //
    23  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    24  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    25  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    26  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    27  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    28  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    29  // THE SOFTWARE.
    30  
    31  package sym
    32  
    33  type Symbols struct {
    34  	symbolBatch []Symbol
    35  
    36  	// Symbol lookup based on name and indexed by version.
    37  	hash []map[string]*Symbol
    38  
    39  	Allsym []*Symbol
    40  }
    41  
    42  func NewSymbols() *Symbols {
    43  	return &Symbols{
    44  		hash: []map[string]*Symbol{
    45  			// preallocate about 2mb for hash of
    46  			// non static symbols
    47  			make(map[string]*Symbol, 100000),
    48  		},
    49  		Allsym: make([]*Symbol, 0, 100000),
    50  	}
    51  }
    52  
    53  func (syms *Symbols) Newsym(name string, v int) *Symbol {
    54  	batch := syms.symbolBatch
    55  	if len(batch) == 0 {
    56  		batch = make([]Symbol, 1000)
    57  	}
    58  	s := &batch[0]
    59  	syms.symbolBatch = batch[1:]
    60  
    61  	s.Dynid = -1
    62  	s.Plt = -1
    63  	s.Got = -1
    64  	s.Name = name
    65  	s.Version = int16(v)
    66  	syms.Allsym = append(syms.Allsym, s)
    67  
    68  	return s
    69  }
    70  
    71  // Look up the symbol with the given name and version, creating the
    72  // symbol if it is not found.
    73  func (syms *Symbols) Lookup(name string, v int) *Symbol {
    74  	m := syms.hash[v]
    75  	s := m[name]
    76  	if s != nil {
    77  		return s
    78  	}
    79  	s = syms.Newsym(name, v)
    80  	s.Extname = s.Name
    81  	m[name] = s
    82  	return s
    83  }
    84  
    85  // Look up the symbol with the given name and version, returning nil
    86  // if it is not found.
    87  func (syms *Symbols) ROLookup(name string, v int) *Symbol {
    88  	return syms.hash[v][name]
    89  }
    90  
    91  // Allocate a new version (i.e. symbol namespace).
    92  func (syms *Symbols) IncVersion() int {
    93  	syms.hash = append(syms.hash, make(map[string]*Symbol))
    94  	return len(syms.hash) - 1
    95  }
    96  
    97  // Rename renames a symbol.
    98  func (syms *Symbols) Rename(old, new string, v int) {
    99  	s := syms.hash[v][old]
   100  	s.Name = new
   101  	if s.Extname == old {
   102  		s.Extname = new
   103  	}
   104  	delete(syms.hash[v], old)
   105  
   106  	dup := syms.hash[v][new]
   107  	if dup == nil {
   108  		syms.hash[v][new] = s
   109  	} else {
   110  		if s.Type == 0 {
   111  			*s = *dup
   112  		} else if dup.Type == 0 {
   113  			*dup = *s
   114  			syms.hash[v][new] = s
   115  		}
   116  	}
   117  }