github.com/hikaru7719/go@v0.0.0-20181025140707-c8b2ac68906a/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.Name = name
    63  	s.Version = int16(v)
    64  	syms.Allsym = append(syms.Allsym, s)
    65  
    66  	return s
    67  }
    68  
    69  // Look up the symbol with the given name and version, creating the
    70  // symbol if it is not found.
    71  func (syms *Symbols) Lookup(name string, v int) *Symbol {
    72  	m := syms.hash[v]
    73  	s := m[name]
    74  	if s != nil {
    75  		return s
    76  	}
    77  	s = syms.Newsym(name, v)
    78  	m[name] = s
    79  	return s
    80  }
    81  
    82  // Look up the symbol with the given name and version, returning nil
    83  // if it is not found.
    84  func (syms *Symbols) ROLookup(name string, v int) *Symbol {
    85  	return syms.hash[v][name]
    86  }
    87  
    88  // Allocate a new version (i.e. symbol namespace).
    89  func (syms *Symbols) IncVersion() int {
    90  	syms.hash = append(syms.hash, make(map[string]*Symbol))
    91  	return len(syms.hash) - 1
    92  }
    93  
    94  // Rename renames a symbol.
    95  func (syms *Symbols) Rename(old, new string, v int, reachparent map[*Symbol]*Symbol) {
    96  	s := syms.hash[v][old]
    97  	oldExtName := s.Extname()
    98  	s.Name = new
    99  	if oldExtName == old {
   100  		s.SetExtname(new)
   101  	}
   102  	delete(syms.hash[v], old)
   103  
   104  	dup := syms.hash[v][new]
   105  	if dup == nil {
   106  		syms.hash[v][new] = s
   107  	} else {
   108  		if s.Type == 0 {
   109  			dup.Attr |= s.Attr
   110  			if s.Attr.Reachable() && reachparent != nil {
   111  				reachparent[dup] = reachparent[s]
   112  			}
   113  			*s = *dup
   114  		} else if dup.Type == 0 {
   115  			s.Attr |= dup.Attr
   116  			if dup.Attr.Reachable() && reachparent != nil {
   117  				reachparent[s] = reachparent[dup]
   118  			}
   119  			*dup = *s
   120  			syms.hash[v][new] = s
   121  		}
   122  	}
   123  }