Source file src/pkg/cmd/link/internal/ld/typelink.go

     1	// Copyright 2016 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	package ld
     6	
     7	import (
     8		"cmd/internal/objabi"
     9		"cmd/link/internal/sym"
    10		"sort"
    11	)
    12	
    13	type byTypeStr []typelinkSortKey
    14	
    15	type typelinkSortKey struct {
    16		TypeStr string
    17		Type    *sym.Symbol
    18	}
    19	
    20	func (s byTypeStr) Less(i, j int) bool { return s[i].TypeStr < s[j].TypeStr }
    21	func (s byTypeStr) Len() int           { return len(s) }
    22	func (s byTypeStr) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
    23	
    24	// typelink generates the typelink table which is used by reflect.typelinks().
    25	// Types that should be added to the typelinks table are marked with the
    26	// MakeTypelink attribute by the compiler.
    27	func (ctxt *Link) typelink() {
    28		typelinks := byTypeStr{}
    29		for _, s := range ctxt.Syms.Allsym {
    30			if s.Attr.Reachable() && s.Attr.MakeTypelink() {
    31				typelinks = append(typelinks, typelinkSortKey{decodetypeStr(ctxt.Arch, s), s})
    32			}
    33		}
    34		sort.Sort(typelinks)
    35	
    36		tl := ctxt.Syms.Lookup("runtime.typelink", 0)
    37		tl.Type = sym.STYPELINK
    38		tl.Attr |= sym.AttrReachable | sym.AttrLocal
    39		tl.Size = int64(4 * len(typelinks))
    40		tl.P = make([]byte, tl.Size)
    41		tl.R = make([]sym.Reloc, len(typelinks))
    42		for i, s := range typelinks {
    43			r := &tl.R[i]
    44			r.Sym = s.Type
    45			r.Off = int32(i * 4)
    46			r.Siz = 4
    47			r.Type = objabi.R_ADDROFF
    48		}
    49	}
    50	

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