mirror of
https://github.com/cwinfo/matterbridge.git
synced 2024-11-27 05:21:39 +00:00
601 lines
13 KiB
Go
601 lines
13 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package dwarf generates DWARF debugging information.
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// DWARF generation is split between the compiler and the linker,
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// this package contains the shared code.
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package dwarf
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import (
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"fmt"
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)
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// InfoPrefix is the prefix for all the symbols containing DWARF info entries.
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const InfoPrefix = "go.info."
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// Sym represents a symbol.
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type Sym interface {
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}
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// A Var represents a local variable or a function parameter.
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type Var struct {
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Name string
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Abbrev int // Either DW_ABRV_AUTO or DW_ABRV_PARAM
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Offset int32
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Type Sym
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Link *Var
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}
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// A Context specifies how to add data to a Sym.
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type Context interface {
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PtrSize() int
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AddInt(s Sym, size int, i int64)
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AddBytes(s Sym, b []byte)
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AddAddress(s Sym, t interface{}, ofs int64)
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AddSectionOffset(s Sym, size int, t interface{}, ofs int64)
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AddString(s Sym, v string)
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SymValue(s Sym) int64
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}
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// AppendUleb128 appends v to b using DWARF's unsigned LEB128 encoding.
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func AppendUleb128(b []byte, v uint64) []byte {
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for {
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c := uint8(v & 0x7f)
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v >>= 7
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if v != 0 {
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c |= 0x80
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}
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b = append(b, c)
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if c&0x80 == 0 {
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break
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}
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}
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return b
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}
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// AppendSleb128 appends v to b using DWARF's signed LEB128 encoding.
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func AppendSleb128(b []byte, v int64) []byte {
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for {
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c := uint8(v & 0x7f)
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s := uint8(v & 0x40)
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v >>= 7
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if (v != -1 || s == 0) && (v != 0 || s != 0) {
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c |= 0x80
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}
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b = append(b, c)
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if c&0x80 == 0 {
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break
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}
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}
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return b
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}
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var encbuf [20]byte
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// AppendUleb128 appends v to s using DWARF's unsigned LEB128 encoding.
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func Uleb128put(ctxt Context, s Sym, v int64) {
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b := AppendUleb128(encbuf[:0], uint64(v))
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ctxt.AddBytes(s, b)
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}
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// AppendUleb128 appends v to s using DWARF's signed LEB128 encoding.
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func Sleb128put(ctxt Context, s Sym, v int64) {
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b := AppendSleb128(encbuf[:0], v)
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ctxt.AddBytes(s, b)
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}
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/*
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* Defining Abbrevs. This is hardcoded, and there will be
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* only a handful of them. The DWARF spec places no restriction on
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* the ordering of attributes in the Abbrevs and DIEs, and we will
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* always write them out in the order of declaration in the abbrev.
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*/
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type dwAttrForm struct {
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attr uint16
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form uint8
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}
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// Go-specific type attributes.
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const (
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DW_AT_go_kind = 0x2900
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DW_AT_go_key = 0x2901
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DW_AT_go_elem = 0x2902
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DW_AT_internal_location = 253 // params and locals; not emitted
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)
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// Index into the abbrevs table below.
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// Keep in sync with ispubname() and ispubtype() below.
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// ispubtype considers >= NULLTYPE public
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const (
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DW_ABRV_NULL = iota
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DW_ABRV_COMPUNIT
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DW_ABRV_FUNCTION
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DW_ABRV_VARIABLE
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DW_ABRV_AUTO
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DW_ABRV_PARAM
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DW_ABRV_STRUCTFIELD
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DW_ABRV_FUNCTYPEPARAM
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DW_ABRV_DOTDOTDOT
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DW_ABRV_ARRAYRANGE
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DW_ABRV_NULLTYPE
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DW_ABRV_BASETYPE
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DW_ABRV_ARRAYTYPE
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DW_ABRV_CHANTYPE
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DW_ABRV_FUNCTYPE
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DW_ABRV_IFACETYPE
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DW_ABRV_MAPTYPE
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DW_ABRV_PTRTYPE
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DW_ABRV_BARE_PTRTYPE // only for void*, no DW_AT_type attr to please gdb 6.
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DW_ABRV_SLICETYPE
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DW_ABRV_STRINGTYPE
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DW_ABRV_STRUCTTYPE
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DW_ABRV_TYPEDECL
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DW_NABRV
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)
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type dwAbbrev struct {
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tag uint8
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children uint8
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attr []dwAttrForm
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}
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var abbrevs = [DW_NABRV]dwAbbrev{
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/* The mandatory DW_ABRV_NULL entry. */
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{0, 0, []dwAttrForm{}},
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/* COMPUNIT */
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{
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DW_TAG_compile_unit,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_language, DW_FORM_data1},
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{DW_AT_low_pc, DW_FORM_addr},
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{DW_AT_high_pc, DW_FORM_addr},
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{DW_AT_stmt_list, DW_FORM_data4},
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{DW_AT_comp_dir, DW_FORM_string},
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},
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},
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/* FUNCTION */
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{
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DW_TAG_subprogram,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_low_pc, DW_FORM_addr},
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{DW_AT_high_pc, DW_FORM_addr},
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{DW_AT_external, DW_FORM_flag},
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},
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},
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/* VARIABLE */
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{
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DW_TAG_variable,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_location, DW_FORM_block1},
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{DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_external, DW_FORM_flag},
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},
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},
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/* AUTO */
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{
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DW_TAG_variable,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_location, DW_FORM_block1},
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{DW_AT_type, DW_FORM_ref_addr},
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},
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},
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/* PARAM */
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{
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DW_TAG_formal_parameter,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_location, DW_FORM_block1},
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{DW_AT_type, DW_FORM_ref_addr},
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},
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},
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/* STRUCTFIELD */
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{
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DW_TAG_member,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_data_member_location, DW_FORM_block1},
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{DW_AT_type, DW_FORM_ref_addr},
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},
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},
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/* FUNCTYPEPARAM */
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{
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DW_TAG_formal_parameter,
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DW_CHILDREN_no,
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// No name!
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[]dwAttrForm{
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{DW_AT_type, DW_FORM_ref_addr},
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},
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},
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/* DOTDOTDOT */
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{
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DW_TAG_unspecified_parameters,
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DW_CHILDREN_no,
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[]dwAttrForm{},
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},
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/* ARRAYRANGE */
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{
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DW_TAG_subrange_type,
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DW_CHILDREN_no,
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// No name!
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[]dwAttrForm{
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{DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_count, DW_FORM_udata},
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},
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},
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// Below here are the types considered public by ispubtype
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/* NULLTYPE */
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{
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DW_TAG_unspecified_type,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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},
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},
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/* BASETYPE */
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{
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DW_TAG_base_type,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_encoding, DW_FORM_data1},
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{DW_AT_byte_size, DW_FORM_data1},
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{DW_AT_go_kind, DW_FORM_data1},
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},
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},
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/* ARRAYTYPE */
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// child is subrange with upper bound
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{
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DW_TAG_array_type,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_byte_size, DW_FORM_udata},
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{DW_AT_go_kind, DW_FORM_data1},
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},
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},
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/* CHANTYPE */
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{
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DW_TAG_typedef,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_go_kind, DW_FORM_data1},
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{DW_AT_go_elem, DW_FORM_ref_addr},
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},
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},
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/* FUNCTYPE */
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{
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DW_TAG_subroutine_type,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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// {DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_go_kind, DW_FORM_data1},
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},
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},
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/* IFACETYPE */
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{
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DW_TAG_typedef,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_go_kind, DW_FORM_data1},
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},
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},
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/* MAPTYPE */
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{
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DW_TAG_typedef,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_go_kind, DW_FORM_data1},
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{DW_AT_go_key, DW_FORM_ref_addr},
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{DW_AT_go_elem, DW_FORM_ref_addr},
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},
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},
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/* PTRTYPE */
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{
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DW_TAG_pointer_type,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_type, DW_FORM_ref_addr},
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{DW_AT_go_kind, DW_FORM_data1},
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},
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},
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/* BARE_PTRTYPE */
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{
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DW_TAG_pointer_type,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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},
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},
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/* SLICETYPE */
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{
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DW_TAG_structure_type,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_byte_size, DW_FORM_udata},
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{DW_AT_go_kind, DW_FORM_data1},
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{DW_AT_go_elem, DW_FORM_ref_addr},
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},
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},
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/* STRINGTYPE */
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{
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DW_TAG_structure_type,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_byte_size, DW_FORM_udata},
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{DW_AT_go_kind, DW_FORM_data1},
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},
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},
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/* STRUCTTYPE */
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{
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DW_TAG_structure_type,
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DW_CHILDREN_yes,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_byte_size, DW_FORM_udata},
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{DW_AT_go_kind, DW_FORM_data1},
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},
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},
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/* TYPEDECL */
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{
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DW_TAG_typedef,
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DW_CHILDREN_no,
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[]dwAttrForm{
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{DW_AT_name, DW_FORM_string},
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{DW_AT_type, DW_FORM_ref_addr},
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},
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},
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}
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// GetAbbrev returns the contents of the .debug_abbrev section.
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func GetAbbrev() []byte {
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var buf []byte
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for i := 1; i < DW_NABRV; i++ {
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// See section 7.5.3
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buf = AppendUleb128(buf, uint64(i))
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buf = AppendUleb128(buf, uint64(abbrevs[i].tag))
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buf = append(buf, byte(abbrevs[i].children))
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for _, f := range abbrevs[i].attr {
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buf = AppendUleb128(buf, uint64(f.attr))
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buf = AppendUleb128(buf, uint64(f.form))
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}
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buf = append(buf, 0, 0)
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}
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return append(buf, 0)
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}
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/*
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* Debugging Information Entries and their attributes.
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*/
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// DWAttr represents an attribute of a DWDie.
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//
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// For DW_CLS_string and _block, value should contain the length, and
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// data the data, for _reference, value is 0 and data is a DWDie* to
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// the referenced instance, for all others, value is the whole thing
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// and data is null.
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type DWAttr struct {
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Link *DWAttr
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Atr uint16 // DW_AT_
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Cls uint8 // DW_CLS_
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Value int64
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Data interface{}
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}
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// DWDie represents a DWARF debug info entry.
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type DWDie struct {
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Abbrev int
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Link *DWDie
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Child *DWDie
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Attr *DWAttr
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Sym Sym
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}
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func putattr(ctxt Context, s Sym, abbrev int, form int, cls int, value int64, data interface{}) error {
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switch form {
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case DW_FORM_addr: // address
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ctxt.AddAddress(s, data, value)
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case DW_FORM_block1: // block
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if cls == DW_CLS_ADDRESS {
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ctxt.AddInt(s, 1, int64(1+ctxt.PtrSize()))
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ctxt.AddInt(s, 1, DW_OP_addr)
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ctxt.AddAddress(s, data, 0)
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break
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}
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value &= 0xff
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ctxt.AddInt(s, 1, value)
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p := data.([]byte)[:value]
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ctxt.AddBytes(s, p)
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case DW_FORM_block2: // block
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value &= 0xffff
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ctxt.AddInt(s, 2, value)
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p := data.([]byte)[:value]
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ctxt.AddBytes(s, p)
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case DW_FORM_block4: // block
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value &= 0xffffffff
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ctxt.AddInt(s, 4, value)
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p := data.([]byte)[:value]
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ctxt.AddBytes(s, p)
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case DW_FORM_block: // block
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Uleb128put(ctxt, s, value)
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p := data.([]byte)[:value]
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ctxt.AddBytes(s, p)
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case DW_FORM_data1: // constant
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ctxt.AddInt(s, 1, value)
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case DW_FORM_data2: // constant
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ctxt.AddInt(s, 2, value)
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case DW_FORM_data4: // constant, {line,loclist,mac,rangelist}ptr
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if cls == DW_CLS_PTR { // DW_AT_stmt_list
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ctxt.AddSectionOffset(s, 4, data, 0)
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break
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}
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ctxt.AddInt(s, 4, value)
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case DW_FORM_data8: // constant, {line,loclist,mac,rangelist}ptr
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ctxt.AddInt(s, 8, value)
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case DW_FORM_sdata: // constant
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Sleb128put(ctxt, s, value)
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case DW_FORM_udata: // constant
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Uleb128put(ctxt, s, value)
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case DW_FORM_string: // string
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str := data.(string)
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ctxt.AddString(s, str)
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// TODO(ribrdb): verify padded strings are never used and remove this
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for i := int64(len(str)); i < value; i++ {
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ctxt.AddInt(s, 1, 0)
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}
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case DW_FORM_flag: // flag
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if value != 0 {
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ctxt.AddInt(s, 1, 1)
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} else {
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ctxt.AddInt(s, 1, 0)
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}
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// In DWARF 2 (which is what we claim to generate),
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// the ref_addr is the same size as a normal address.
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// In DWARF 3 it is always 32 bits, unless emitting a large
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// (> 4 GB of debug info aka "64-bit") unit, which we don't implement.
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case DW_FORM_ref_addr: // reference to a DIE in the .info section
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if data == nil {
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return fmt.Errorf("dwarf: null reference in %d", abbrev)
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} else {
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ctxt.AddSectionOffset(s, ctxt.PtrSize(), data, 0)
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}
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case DW_FORM_ref1, // reference within the compilation unit
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DW_FORM_ref2, // reference
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DW_FORM_ref4, // reference
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DW_FORM_ref8, // reference
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DW_FORM_ref_udata, // reference
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DW_FORM_strp, // string
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DW_FORM_indirect: // (see Section 7.5.3)
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fallthrough
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default:
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return fmt.Errorf("dwarf: unsupported attribute form %d / class %d", form, cls)
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}
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return nil
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}
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// PutAttrs writes the attributes for a DIE to symbol 's'.
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//
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// Note that we can (and do) add arbitrary attributes to a DIE, but
|
|
// only the ones actually listed in the Abbrev will be written out.
|
|
func PutAttrs(ctxt Context, s Sym, abbrev int, attr *DWAttr) {
|
|
Outer:
|
|
for _, f := range abbrevs[abbrev].attr {
|
|
for ap := attr; ap != nil; ap = ap.Link {
|
|
if ap.Atr == f.attr {
|
|
putattr(ctxt, s, abbrev, int(f.form), int(ap.Cls), ap.Value, ap.Data)
|
|
continue Outer
|
|
}
|
|
}
|
|
|
|
putattr(ctxt, s, abbrev, int(f.form), 0, 0, nil)
|
|
}
|
|
}
|
|
|
|
// HasChildren returns true if 'die' uses an abbrev that supports children.
|
|
func HasChildren(die *DWDie) bool {
|
|
return abbrevs[die.Abbrev].children != 0
|
|
}
|
|
|
|
// PutFunc writes a DIE for a function to s.
|
|
// It also writes child DIEs for each variable in vars.
|
|
func PutFunc(ctxt Context, s Sym, name string, external bool, startPC Sym, size int64, vars *Var) {
|
|
Uleb128put(ctxt, s, DW_ABRV_FUNCTION)
|
|
putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name)
|
|
putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_addr, DW_CLS_ADDRESS, 0, startPC)
|
|
putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_addr, DW_CLS_ADDRESS, size+ctxt.SymValue(startPC), startPC)
|
|
var ev int64
|
|
if external {
|
|
ev = 1
|
|
}
|
|
putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_flag, DW_CLS_FLAG, ev, 0)
|
|
names := make(map[string]bool)
|
|
for v := vars; v != nil; v = v.Link {
|
|
var n string
|
|
if names[v.Name] {
|
|
n = fmt.Sprintf("%s#%d", v.Name, len(names))
|
|
} else {
|
|
n = v.Name
|
|
}
|
|
names[n] = true
|
|
|
|
Uleb128put(ctxt, s, int64(v.Abbrev))
|
|
putattr(ctxt, s, v.Abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(n)), n)
|
|
loc := append(encbuf[:0], DW_OP_call_frame_cfa)
|
|
if v.Offset != 0 {
|
|
loc = append(loc, DW_OP_consts)
|
|
loc = AppendSleb128(loc, int64(v.Offset))
|
|
loc = append(loc, DW_OP_plus)
|
|
}
|
|
putattr(ctxt, s, v.Abbrev, DW_FORM_block1, DW_CLS_BLOCK, int64(len(loc)), loc)
|
|
putattr(ctxt, s, v.Abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, v.Type)
|
|
|
|
}
|
|
Uleb128put(ctxt, s, 0)
|
|
}
|