// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package dwarf generates DWARF debugging information.
// DWARF generation is split between the compiler and the linker,
// this package contains the shared code.
package dwarf
import (
"bytes"
"cmd/internal/objabi"
"errors"
"fmt"
"os/exec"
"sort"
"strconv"
"strings"
)
// InfoPrefix is the prefix for all the symbols containing DWARF info entries.
const InfoPrefix = "go.info."
// RangePrefix is the prefix for all the symbols containing DWARF location lists.
const LocPrefix = "go.loc."
// RangePrefix is the prefix for all the symbols containing DWARF range lists.
const RangePrefix = "go.range."
// IsStmtPrefix is the prefix for all the symbols containing DWARF is_stmt info for the line number table.
const IsStmtPrefix = "go.isstmt."
// ConstInfoPrefix is the prefix for all symbols containing DWARF info
// entries that contain constants.
const ConstInfoPrefix = "go.constinfo."
// CUInfoPrefix is the prefix for symbols containing information to
// populate the DWARF compilation unit info entries.
const CUInfoPrefix = "go.cuinfo."
// Used to form the symbol name assigned to the DWARF 'abstract subprogram"
// info entry for a function
const AbstractFuncSuffix = "$abstract"
// Controls logging/debugging for selected aspects of DWARF subprogram
// generation (functions, scopes).
var logDwarf bool
// Sym represents a symbol.
type Sym interface {
Len() int64
}
// A Var represents a local variable or a function parameter.
type Var struct {
Name string
Abbrev int // Either DW_ABRV_AUTO[_LOCLIST] or DW_ABRV_PARAM[_LOCLIST]
IsReturnValue bool
IsInlFormal bool
StackOffset int32
// This package can't use the ssa package, so it can't mention ssa.FuncDebug,
// so indirect through a closure.
PutLocationList func(listSym, startPC Sym)
Scope int32
Type Sym
DeclFile string
DeclLine uint
DeclCol uint
InlIndex int32 // subtract 1 to form real index into InlTree
ChildIndex int32 // child DIE index in abstract function
IsInAbstract bool // variable exists in abstract function
}
// A Scope represents a lexical scope. All variables declared within a
// scope will only be visible to instructions covered by the scope.
// Lexical scopes are contiguous in source files but can end up being
// compiled to discontiguous blocks of instructions in the executable.
// The Ranges field lists all the blocks of instructions that belong
// in this scope.
type Scope struct {
Parent int32
Ranges []Range
Vars []*Var
}
// A Range represents a half-open interval [Start, End).
type Range struct {
Start, End int64
}
// This container is used by the PutFunc* variants below when
// creating the DWARF subprogram DIE(s) for a function.
type FnState struct {
Name string
Importpath string
Info Sym
Filesym Sym
Loc Sym
Ranges Sym
Absfn Sym
StartPC Sym
Size int64
External bool
Scopes []Scope
InlCalls InlCalls
UseBASEntries bool
}
func EnableLogging(doit bool) {
logDwarf = doit
}
// UnifyRanges merges the list of ranges of c into the list of ranges of s
func (s *Scope) UnifyRanges(c *Scope) {
out := make([]Range, 0, len(s.Ranges)+len(c.Ranges))
i, j := 0, 0
for {
var cur Range
if i < len(s.Ranges) && j < len(c.Ranges) {
if s.Ranges[i].Start < c.Ranges[j].Start {
cur = s.Ranges[i]
i++
} else {
cur = c.Ranges[j]
j++
}
} else if i < len(s.Ranges) {
cur = s.Ranges[i]
i++
} else if j < len(c.Ranges) {
cur = c.Ranges[j]
j++
} else {
break
}
if n := len(out); n > 0 && cur.Start <= out[n-1].End {
out[n-1].End = cur.End
} else {
out = append(out, cur)
}
}
s.Ranges = out
}
// AppendRange adds r to s, if r is non-empty.
// If possible, it extends the last Range in s.Ranges; if not, it creates a new one.
func (s *Scope) AppendRange(r Range) {
if r.End <= r.Start {
return
}
i := len(s.Ranges)
if i > 0 && s.Ranges[i-1].End == r.Start {
s.Ranges[i-1].End = r.End
return
}
s.Ranges = append(s.Ranges, r)
}
type InlCalls struct {
Calls []InlCall
}
type InlCall struct {
// index into ctx.InlTree describing the call inlined here
InlIndex int
// Symbol of file containing inlined call site (really *obj.LSym).
CallFile Sym
// Line number of inlined call site.
CallLine uint32
// Dwarf abstract subroutine symbol (really *obj.LSym).
AbsFunSym Sym
// Indices of child inlines within Calls array above.
Children []int
// entries in this list are PAUTO's created by the inliner to
// capture the promoted formals and locals of the inlined callee.
InlVars []*Var
// PC ranges for this inlined call.
Ranges []Range
// Root call (not a child of some other call).
Root bool
}
// A Context specifies how to add data to a Sym.
type Context interface {
PtrSize() int
AddInt(s Sym, size int, i int64)
AddBytes(s Sym, b []byte)
AddAddress(s Sym, t interface{}, ofs int64)
AddCURelativeAddress(s Sym, t interface{}, ofs int64)
AddSectionOffset(s Sym, size int, t interface{}, ofs int64)
AddDWARFAddrSectionOffset(s Sym, t interface{}, ofs int64)
CurrentOffset(s Sym) int64
RecordDclReference(from Sym, to Sym, dclIdx int, inlIndex int)
RecordChildDieOffsets(s Sym, vars []*Var, offsets []int32)
AddString(s Sym, v string)
AddFileRef(s Sym, f interface{})
Logf(format string, args ...interface{})
}
// AppendUleb128 appends v to b using DWARF's unsigned LEB128 encoding.
func AppendUleb128(b []byte, v uint64) []byte {
for {
c := uint8(v & 0x7f)
v >>= 7
if v != 0 {
c |= 0x80
}
b = append(b, c)
if c&0x80 == 0 {
break
}
}
return b
}
// AppendSleb128 appends v to b using DWARF's signed LEB128 encoding.
func AppendSleb128(b []byte, v int64) []byte {
for {
c := uint8(v & 0x7f)
s := uint8(v & 0x40)
v >>= 7
if (v != -1 || s == 0) && (v != 0 || s != 0) {
c |= 0x80
}
b = append(b, c)
if c&0x80 == 0 {
break
}
}
return b
}
// sevenbits contains all unsigned seven bit numbers, indexed by their value.
var sevenbits = [...]byte{
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
}
// sevenBitU returns the unsigned LEB128 encoding of v if v is seven bits and nil otherwise.
// The contents of the returned slice must not be modified.
func sevenBitU(v int64) []byte {
if uint64(v) < uint64(len(sevenbits)) {
return sevenbits[v : v+1]
}
return nil
}
// sevenBitS returns the signed LEB128 encoding of v if v is seven bits and nil otherwise.
// The contents of the returned slice must not be modified.
func sevenBitS(v int64) []byte {
if uint64(v) <= 63 {
return sevenbits[v : v+1]
}
if uint64(-v) <= 64 {
return sevenbits[128+v : 128+v+1]
}
return nil
}
// Uleb128put appends v to s using DWARF's unsigned LEB128 encoding.
func Uleb128put(ctxt Context, s Sym, v int64) {
b := sevenBitU(v)
if b == nil {
var encbuf [20]byte
b = AppendUleb128(encbuf[:0], uint64(v))
}
ctxt.AddBytes(s, b)
}
// Sleb128put appends v to s using DWARF's signed LEB128 encoding.
func Sleb128put(ctxt Context, s Sym, v int64) {
b := sevenBitS(v)
if b == nil {
var encbuf [20]byte
b = AppendSleb128(encbuf[:0], v)
}
ctxt.AddBytes(s, b)
}
/*
* Defining Abbrevs. This is hardcoded on a per-platform basis (that is,
* each platform will see a fixed abbrev table for all objects); the number
* of abbrev entries is fairly small (compared to C++ objects). The DWARF
* spec places no restriction on the ordering of attributes in the
* Abbrevs and DIEs, and we will always write them out in the order
* of declaration in the abbrev.
*/
type dwAttrForm struct {
attr uint16
form uint8
}
// Go-specific type attributes.
const (
DW_AT_go_kind = 0x2900
DW_AT_go_key = 0x2901
DW_AT_go_elem = 0x2902
// Attribute for DW_TAG_member of a struct type.
// Nonzero value indicates the struct field is an embedded field.
DW_AT_go_embedded_field = 0x2903
DW_AT_go_runtime_type = 0x2904
DW_AT_go_package_name = 0x2905 // Attribute for DW_TAG_compile_unit
DW_AT_internal_location = 253 // params and locals; not emitted
)
// Index into the abbrevs table below.
// Keep in sync with ispubname() and ispubtype() in ld/dwarf.go.
// ispubtype considers >= NULLTYPE public
const (
DW_ABRV_NULL = iota
DW_ABRV_COMPUNIT
DW_ABRV_COMPUNIT_TEXTLESS
DW_ABRV_FUNCTION
DW_ABRV_FUNCTION_ABSTRACT
DW_ABRV_FUNCTION_CONCRETE
DW_ABRV_INLINED_SUBROUTINE
DW_ABRV_INLINED_SUBROUTINE_RANGES
DW_ABRV_VARIABLE
DW_ABRV_INT_CONSTANT
DW_ABRV_AUTO
DW_ABRV_AUTO_LOCLIST
DW_ABRV_AUTO_ABSTRACT
DW_ABRV_AUTO_CONCRETE
DW_ABRV_AUTO_CONCRETE_LOCLIST
DW_ABRV_PARAM
DW_ABRV_PARAM_LOCLIST
DW_ABRV_PARAM_ABSTRACT
DW_ABRV_PARAM_CONCRETE
DW_ABRV_PARAM_CONCRETE_LOCLIST
DW_ABRV_LEXICAL_BLOCK_RANGES
DW_ABRV_LEXICAL_BLOCK_SIMPLE
DW_ABRV_STRUCTFIELD
DW_ABRV_FUNCTYPEPARAM
DW_ABRV_DOTDOTDOT
DW_ABRV_ARRAYRANGE
DW_ABRV_NULLTYPE
DW_ABRV_BASETYPE
DW_ABRV_ARRAYTYPE
DW_ABRV_CHANTYPE
DW_ABRV_FUNCTYPE
DW_ABRV_IFACETYPE
DW_ABRV_MAPTYPE
DW_ABRV_PTRTYPE
DW_ABRV_BARE_PTRTYPE // only for void*, no DW_AT_type attr to please gdb 6.
DW_ABRV_SLICETYPE
DW_ABRV_STRINGTYPE
DW_ABRV_STRUCTTYPE
DW_ABRV_TYPEDECL
DW_NABRV
)
type dwAbbrev struct {
tag uint8
children uint8
attr []dwAttrForm
}
var abbrevsFinalized bool
// expandPseudoForm takes an input DW_FORM_xxx value and translates it
// into a platform-appropriate concrete form. Existing concrete/real
// DW_FORM values are left untouched. For the moment the only
// pseudo-form is DW_FORM_udata_pseudo, which gets expanded to
// DW_FORM_data4 on Darwin and DW_FORM_udata everywhere else. See
// issue #31459 for more context.
func expandPseudoForm(form uint8) uint8 {
// Is this a pseudo-form?
if form != DW_FORM_udata_pseudo {
return form
}
expandedForm := DW_FORM_udata
if objabi.GOOS == "darwin" {
expandedForm = DW_FORM_data4
}
return uint8(expandedForm)
}
// Abbrevs() returns the finalized abbrev array for the platform,
// expanding any DW_FORM pseudo-ops to real values.
func Abbrevs() [DW_NABRV]dwAbbrev {
if abbrevsFinalized {
return abbrevs
}
for i := 1; i < DW_NABRV; i++ {
for j := 0; j < len(abbrevs[i].attr); j++ {
abbrevs[i].attr[j].form = expandPseudoForm(abbrevs[i].attr[j].form)
}
}
abbrevsFinalized = true
return abbrevs
}
// abbrevs is a raw table of abbrev entries; it needs to be post-processed
// by the Abbrevs() function above prior to being consumed, to expand
// the 'pseudo-form' entries below to real DWARF form values.
var abbrevs = [DW_NABRV]dwAbbrev{
/* The mandatory DW_ABRV_NULL entry. */
{0, 0, []dwAttrForm{}},
/* COMPUNIT */
{
DW_TAG_compile_unit,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_language, DW_FORM_data1},
{DW_AT_stmt_list, DW_FORM_sec_offset},
{DW_AT_low_pc, DW_FORM_addr},
{DW_AT_ranges, DW_FORM_sec_offset},
{DW_AT_comp_dir, DW_FORM_string},
{DW_AT_producer, DW_FORM_string},
{DW_AT_go_package_name, DW_FORM_string},
},
},
/* COMPUNIT_TEXTLESS */
{
DW_TAG_compile_unit,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_language, DW_FORM_data1},
{DW_AT_comp_dir, DW_FORM_string},
{DW_AT_producer, DW_FORM_string},
{DW_AT_go_package_name, DW_FORM_string},
},
},
/* FUNCTION */
{
DW_TAG_subprogram,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_low_pc, DW_FORM_addr},
{DW_AT_high_pc, DW_FORM_addr},
{DW_AT_frame_base, DW_FORM_block1},
{DW_AT_decl_file, DW_FORM_data4},
{DW_AT_external, DW_FORM_flag},
},
},
/* FUNCTION_ABSTRACT */
{
DW_TAG_subprogram,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_inline, DW_FORM_data1},
{DW_AT_external, DW_FORM_flag},
},
},
/* FUNCTION_CONCRETE */
{
DW_TAG_subprogram,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_abstract_origin, DW_FORM_ref_addr},
{DW_AT_low_pc, DW_FORM_addr},
{DW_AT_high_pc, DW_FORM_addr},
{DW_AT_frame_base, DW_FORM_block1},
},
},
/* INLINED_SUBROUTINE */
{
DW_TAG_inlined_subroutine,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_abstract_origin, DW_FORM_ref_addr},
{DW_AT_low_pc, DW_FORM_addr},
{DW_AT_high_pc, DW_FORM_addr},
{DW_AT_call_file, DW_FORM_data4},
{DW_AT_call_line, DW_FORM_udata_pseudo}, // pseudo-form
},
},
/* INLINED_SUBROUTINE_RANGES */
{
DW_TAG_inlined_subroutine,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_abstract_origin, DW_FORM_ref_addr},
{DW_AT_ranges, DW_FORM_sec_offset},
{DW_AT_call_file, DW_FORM_data4},
{DW_AT_call_line, DW_FORM_udata_pseudo}, // pseudo-form
},
},
/* VARIABLE */
{
DW_TAG_variable,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_location, DW_FORM_block1},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_external, DW_FORM_flag},
},
},
/* INT CONSTANT */
{
DW_TAG_constant,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_const_value, DW_FORM_sdata},
},
},
/* AUTO */
{
DW_TAG_variable,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_decl_line, DW_FORM_udata},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_block1},
},
},
/* AUTO_LOCLIST */
{
DW_TAG_variable,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_decl_line, DW_FORM_udata},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_sec_offset},
},
},
/* AUTO_ABSTRACT */
{
DW_TAG_variable,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_decl_line, DW_FORM_udata},
{DW_AT_type, DW_FORM_ref_addr},
},
},
/* AUTO_CONCRETE */
{
DW_TAG_variable,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_abstract_origin, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_block1},
},
},
/* AUTO_CONCRETE_LOCLIST */
{
DW_TAG_variable,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_abstract_origin, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_sec_offset},
},
},
/* PARAM */
{
DW_TAG_formal_parameter,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_variable_parameter, DW_FORM_flag},
{DW_AT_decl_line, DW_FORM_udata},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_block1},
},
},
/* PARAM_LOCLIST */
{
DW_TAG_formal_parameter,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_variable_parameter, DW_FORM_flag},
{DW_AT_decl_line, DW_FORM_udata},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_sec_offset},
},
},
/* PARAM_ABSTRACT */
{
DW_TAG_formal_parameter,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_variable_parameter, DW_FORM_flag},
{DW_AT_type, DW_FORM_ref_addr},
},
},
/* PARAM_CONCRETE */
{
DW_TAG_formal_parameter,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_abstract_origin, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_block1},
},
},
/* PARAM_CONCRETE_LOCLIST */
{
DW_TAG_formal_parameter,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_abstract_origin, DW_FORM_ref_addr},
{DW_AT_location, DW_FORM_sec_offset},
},
},
/* LEXICAL_BLOCK_RANGES */
{
DW_TAG_lexical_block,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_ranges, DW_FORM_sec_offset},
},
},
/* LEXICAL_BLOCK_SIMPLE */
{
DW_TAG_lexical_block,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_low_pc, DW_FORM_addr},
{DW_AT_high_pc, DW_FORM_addr},
},
},
/* STRUCTFIELD */
{
DW_TAG_member,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_data_member_location, DW_FORM_udata},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_go_embedded_field, DW_FORM_flag},
},
},
/* FUNCTYPEPARAM */
{
DW_TAG_formal_parameter,
DW_CHILDREN_no,
// No name!
[]dwAttrForm{
{DW_AT_type, DW_FORM_ref_addr},
},
},
/* DOTDOTDOT */
{
DW_TAG_unspecified_parameters,
DW_CHILDREN_no,
[]dwAttrForm{},
},
/* ARRAYRANGE */
{
DW_TAG_subrange_type,
DW_CHILDREN_no,
// No name!
[]dwAttrForm{
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_count, DW_FORM_udata},
},
},
// Below here are the types considered public by ispubtype
/* NULLTYPE */
{
DW_TAG_unspecified_type,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
},
},
/* BASETYPE */
{
DW_TAG_base_type,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_encoding, DW_FORM_data1},
{DW_AT_byte_size, DW_FORM_data1},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
},
},
/* ARRAYTYPE */
// child is subrange with upper bound
{
DW_TAG_array_type,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_byte_size, DW_FORM_udata},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
},
},
/* CHANTYPE */
{
DW_TAG_typedef,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
{DW_AT_go_elem, DW_FORM_ref_addr},
},
},
/* FUNCTYPE */
{
DW_TAG_subroutine_type,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_byte_size, DW_FORM_udata},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
},
},
/* IFACETYPE */
{
DW_TAG_typedef,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
},
},
/* MAPTYPE */
{
DW_TAG_typedef,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
{DW_AT_go_key, DW_FORM_ref_addr},
{DW_AT_go_elem, DW_FORM_ref_addr},
},
},
/* PTRTYPE */
{
DW_TAG_pointer_type,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
},
},
/* BARE_PTRTYPE */
{
DW_TAG_pointer_type,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
},
},
/* SLICETYPE */
{
DW_TAG_structure_type,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_byte_size, DW_FORM_udata},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
{DW_AT_go_elem, DW_FORM_ref_addr},
},
},
/* STRINGTYPE */
{
DW_TAG_structure_type,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_byte_size, DW_FORM_udata},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
},
},
/* STRUCTTYPE */
{
DW_TAG_structure_type,
DW_CHILDREN_yes,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_byte_size, DW_FORM_udata},
{DW_AT_go_kind, DW_FORM_data1},
{DW_AT_go_runtime_type, DW_FORM_addr},
},
},
/* TYPEDECL */
{
DW_TAG_typedef,
DW_CHILDREN_no,
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_type, DW_FORM_ref_addr},
},
},
}
// GetAbbrev returns the contents of the .debug_abbrev section.
func GetAbbrev() []byte {
abbrevs := Abbrevs()
var buf []byte
for i := 1; i < DW_NABRV; i++ {
// See section 7.5.3
buf = AppendUleb128(buf, uint64(i))
buf = AppendUleb128(buf, uint64(abbrevs[i].tag))
buf = append(buf, abbrevs[i].children)
for _, f := range abbrevs[i].attr {
buf = AppendUleb128(buf, uint64(f.attr))
buf = AppendUleb128(buf, uint64(f.form))
}
buf = append(buf, 0, 0)
}
return append(buf, 0)
}
/*
* Debugging Information Entries and their attributes.
*/
// DWAttr represents an attribute of a DWDie.
//
// For DW_CLS_string and _block, value should contain the length, and
// data the data, for _reference, value is 0 and data is a DWDie* to
// the referenced instance, for all others, value is the whole thing
// and data is null.
type DWAttr struct {
Link *DWAttr
Atr uint16 // DW_AT_
Cls uint8 // DW_CLS_
Value int64
Data interface{}
}
// DWDie represents a DWARF debug info entry.
type DWDie struct {
Abbrev int
Link *DWDie
Child *DWDie
Attr *DWAttr
Sym Sym
}
func putattr(ctxt Context, s Sym, abbrev int, form int, cls int, value int64, data interface{}) error {
switch form {
case DW_FORM_addr: // address
// Allow nil addresses for DW_AT_go_runtime_type.
if data == nil && value == 0 {
ctxt.AddInt(s, ctxt.PtrSize(), 0)
break
}
if cls == DW_CLS_GO_TYPEREF {
ctxt.AddSectionOffset(s, ctxt.PtrSize(), data, value)
break
}
ctxt.AddAddress(s, data, value)
case DW_FORM_block1: // block
if cls == DW_CLS_ADDRESS {
ctxt.AddInt(s, 1, int64(1+ctxt.PtrSize()))
ctxt.AddInt(s, 1, DW_OP_addr)
ctxt.AddAddress(s, data, 0)
break
}
value &= 0xff
ctxt.AddInt(s, 1, value)
p := data.([]byte)[:value]
ctxt.AddBytes(s, p)
case DW_FORM_block2: // block
value &= 0xffff
ctxt.AddInt(s, 2, value)
p := data.([]byte)[:value]
ctxt.AddBytes(s, p)
case DW_FORM_block4: // block
value &= 0xffffffff
ctxt.AddInt(s, 4, value)
p := data.([]byte)[:value]
ctxt.AddBytes(s, p)
case DW_FORM_block: // block
Uleb128put(ctxt, s, value)
p := data.([]byte)[:value]
ctxt.AddBytes(s, p)
case DW_FORM_data1: // constant
ctxt.AddInt(s, 1, value)
case DW_FORM_data2: // constant
ctxt.AddInt(s, 2, value)
case DW_FORM_data4: // constant, {line,loclist,mac,rangelist}ptr
if cls == DW_CLS_PTR { // DW_AT_stmt_list and DW_AT_ranges
ctxt.AddDWARFAddrSectionOffset(s, data, value)
break
}
ctxt.AddInt(s, 4, value)
case DW_FORM_data8: // constant, {line,loclist,mac,rangelist}ptr
ctxt.AddInt(s, 8, value)
case DW_FORM_sdata: // constant
Sleb128put(ctxt, s, value)
case DW_FORM_udata: // constant
Uleb128put(ctxt, s, value)
case DW_FORM_string: // string
str := data.(string)
ctxt.AddString(s, str)
// TODO(ribrdb): verify padded strings are never used and remove this
for i := int64(len(str)); i < value; i++ {
ctxt.AddInt(s, 1, 0)
}
case DW_FORM_flag: // flag
if value != 0 {
ctxt.AddInt(s, 1, 1)
} else {
ctxt.AddInt(s, 1, 0)
}
// As of DWARF 3 the ref_addr is always 32 bits, unless emitting a large
// (> 4 GB of debug info aka "64-bit") unit, which we don't implement.
case DW_FORM_ref_addr: // reference to a DIE in the .info section
fallthrough
case DW_FORM_sec_offset: // offset into a DWARF section other than .info
if data == nil {
return fmt.Errorf("dwarf: null reference in %d", abbrev)
}
ctxt.AddDWARFAddrSectionOffset(s, data, value)
case DW_FORM_ref1, // reference within the compilation unit
DW_FORM_ref2, // reference
DW_FORM_ref4, // reference
DW_FORM_ref8, // reference
DW_FORM_ref_udata, // reference
DW_FORM_strp, // string
DW_FORM_indirect: // (see Section 7.5.3)
fallthrough
default:
return fmt.Errorf("dwarf: unsupported attribute form %d / class %d", form, cls)
}
return nil
}
// PutAttrs writes the attributes for a DIE to symbol 's'.
//
// 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) {
abbrevs := Abbrevs()
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 reports whether 'die' uses an abbrev that supports children.
func HasChildren(die *DWDie) bool {
abbrevs := Abbrevs()
return abbrevs[die.Abbrev].children != 0
}
// PutIntConst writes a DIE for an integer constant
func PutIntConst(ctxt Context, info, typ Sym, name string, val int64) {
Uleb128put(ctxt, info, DW_ABRV_INT_CONSTANT)
putattr(ctxt, info, DW_ABRV_INT_CONSTANT, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name)
putattr(ctxt, info, DW_ABRV_INT_CONSTANT, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, typ)
putattr(ctxt, info, DW_ABRV_INT_CONSTANT, DW_FORM_sdata, DW_CLS_CONSTANT, val, nil)
}
// PutBasedRanges writes a range table to sym. All addresses in ranges are
// relative to some base address, which must be arranged by the caller
// (e.g., with a DW_AT_low_pc attribute, or in a BASE-prefixed range).
func PutBasedRanges(ctxt Context, sym Sym, ranges []Range) {
ps := ctxt.PtrSize()
// Write ranges.
for _, r := range ranges {
ctxt.AddInt(sym, ps, r.Start)
ctxt.AddInt(sym, ps, r.End)
}
// Write trailer.
ctxt.AddInt(sym, ps, 0)
ctxt.AddInt(sym, ps, 0)
}
// PutRanges writes a range table to s.Ranges.
// All addresses in ranges are relative to s.base.
func (s *FnState) PutRanges(ctxt Context, ranges []Range) {
ps := ctxt.PtrSize()
sym, base := s.Ranges, s.StartPC
if s.UseBASEntries {
// Using a Base Address Selection Entry reduces the number of relocations, but
// this is not done on macOS because it is not supported by dsymutil/dwarfdump/lldb
ctxt.AddInt(sym, ps, -1)
ctxt.AddAddress(sym, base, 0)
PutBasedRanges(ctxt, sym, ranges)
return
}
// Write ranges full of relocations
for _, r := range ranges {
ctxt.AddCURelativeAddress(sym, base, r.Start)
ctxt.AddCURelativeAddress(sym, base, r.End)
}
// Write trailer.
ctxt.AddInt(sym, ps, 0)
ctxt.AddInt(sym, ps, 0)
}
// Return TRUE if the inlined call in the specified slot is empty,
// meaning it has a zero-length range (no instructions), and all
// of its children are empty.
func isEmptyInlinedCall(slot int, calls *InlCalls) bool {
ic := &calls.Calls[slot]
if ic.InlIndex == -2 {
return true
}
live := false
for _, k := range ic.Children {
if !isEmptyInlinedCall(k, calls) {
live = true
}
}
if len(ic.Ranges) > 0 {
live = true
}
if !live {
ic.InlIndex = -2
}
return !live
}
// Slot -1: return top-level inlines
// Slot >= 0: return children of that slot
func inlChildren(slot int, calls *InlCalls) []int {
var kids []int
if slot != -1 {
for _, k := range calls.Calls[slot].Children {
if !isEmptyInlinedCall(k, calls) {
kids = append(kids, k)
}
}
} else {
for k := 0; k < len(calls.Calls); k += 1 {
if calls.Calls[k].Root && !isEmptyInlinedCall(k, calls) {
kids = append(kids, k)
}
}
}
return kids
}
func inlinedVarTable(inlcalls *InlCalls) map[*Var]bool {
vars := make(map[*Var]bool)
for _, ic := range inlcalls.Calls {
for _, v := range ic.InlVars {
vars[v] = true
}
}
return vars
}
// The s.Scopes slice contains variables were originally part of the
// function being emitted, as well as variables that were imported
// from various callee functions during the inlining process. This
// function prunes out any variables from the latter category (since
// they will be emitted as part of DWARF inlined_subroutine DIEs) and
// then generates scopes for vars in the former category.
func putPrunedScopes(ctxt Context, s *FnState, fnabbrev int) error {
if len(s.Scopes) == 0 {
return nil
}
scopes := make([]Scope, len(s.Scopes), len(s.Scopes))
pvars := inlinedVarTable(&s.InlCalls)
for k, s := range s.Scopes {
var pruned Scope = Scope{Parent: s.Parent, Ranges: s.Ranges}
for i := 0; i < len(s.Vars); i++ {
_, found := pvars[s.Vars[i]]
if !found {
pruned.Vars = append(pruned.Vars, s.Vars[i])
}
}
sort.Sort(byChildIndex(pruned.Vars))
scopes[k] = pruned
}
var encbuf [20]byte
if putscope(ctxt, s, scopes, 0, fnabbrev, encbuf[:0]) < int32(len(scopes)) {
return errors.New("multiple toplevel scopes")
}
return nil
}
// Emit DWARF attributes and child DIEs for an 'abstract' subprogram.
// The abstract subprogram DIE for a function contains its
// location-independent attributes (name, type, etc). Other instances
// of the function (any inlined copy of it, or the single out-of-line
// 'concrete' instance) will contain a pointer back to this abstract
// DIE (as a space-saving measure, so that name/type etc doesn't have
// to be repeated for each inlined copy).
func PutAbstractFunc(ctxt Context, s *FnState) error {
if logDwarf {
ctxt.Logf("PutAbstractFunc(%v)\n", s.Absfn)
}
abbrev := DW_ABRV_FUNCTION_ABSTRACT
Uleb128put(ctxt, s.Absfn, int64(abbrev))
fullname := s.Name
if strings.HasPrefix(s.Name, "\"\".") {
// Generate a fully qualified name for the function in the
// abstract case. This is so as to avoid the need for the
// linker to process the DIE with patchDWARFName(); we can't
// allow the name attribute of an abstract subprogram DIE to
// be rewritten, since it would change the offsets of the
// child DIEs (which we're relying on in order for abstract
// origin references to work).
fullname = objabi.PathToPrefix(s.Importpath) + "." + s.Name[3:]
}
putattr(ctxt, s.Absfn, abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(fullname)), fullname)
// DW_AT_inlined value
putattr(ctxt, s.Absfn, abbrev, DW_FORM_data1, DW_CLS_CONSTANT, int64(DW_INL_inlined), nil)
var ev int64
if s.External {
ev = 1
}
putattr(ctxt, s.Absfn, abbrev, DW_FORM_flag, DW_CLS_FLAG, ev, 0)
// Child variables (may be empty)
var flattened []*Var
// This slice will hold the offset in bytes for each child var DIE
// with respect to the start of the parent subprogram DIE.
var offsets []int32
// Scopes/vars
if len(s.Scopes) > 0 {
// For abstract subprogram DIEs we want to flatten out scope info:
// lexical scope DIEs contain range and/or hi/lo PC attributes,
// which we explicitly don't want for the abstract subprogram DIE.
pvars := inlinedVarTable(&s.InlCalls)
for _, scope := range s.Scopes {
for i := 0; i < len(scope.Vars); i++ {
_, found := pvars[scope.Vars[i]]
if found || !scope.Vars[i].IsInAbstract {
continue
}
flattened = append(flattened, scope.Vars[i])
}
}
if len(flattened) > 0 {
sort.Sort(byChildIndex(flattened))
if logDwarf {
ctxt.Logf("putAbstractScope(%v): vars:", s.Info)
for i, v := range flattened {
ctxt.Logf(" %d:%s", i, v.Name)
}
ctxt.Logf("\n")
}
// This slice will hold the offset in bytes for each child
// variable DIE with respect to the start of the parent
// subprogram DIE.
for _, v := range flattened {
offsets = append(offsets, int32(ctxt.CurrentOffset(s.Absfn)))
putAbstractVar(ctxt, s.Absfn, v)
}
}
}
ctxt.RecordChildDieOffsets(s.Absfn, flattened, offsets)
Uleb128put(ctxt, s.Absfn, 0)
return nil
}
// Emit DWARF attributes and child DIEs for an inlined subroutine. The
// first attribute of an inlined subroutine DIE is a reference back to
// its corresponding 'abstract' DIE (containing location-independent
// attributes such as name, type, etc). Inlined subroutine DIEs can
// have other inlined subroutine DIEs as children.
func PutInlinedFunc(ctxt Context, s *FnState, callersym Sym, callIdx int) error {
ic := s.InlCalls.Calls[callIdx]
callee := ic.AbsFunSym
abbrev := DW_ABRV_INLINED_SUBROUTINE_RANGES
if len(ic.Ranges) == 1 {
abbrev = DW_ABRV_INLINED_SUBROUTINE
}
Uleb128put(ctxt, s.Info, int64(abbrev))
if logDwarf {
ctxt.Logf("PutInlinedFunc(caller=%v,callee=%v,abbrev=%d)\n", callersym, callee, abbrev)
}
// Abstract origin.
putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, callee)
if abbrev == DW_ABRV_INLINED_SUBROUTINE_RANGES {
putattr(ctxt, s.Info, abbrev, DW_FORM_sec_offset, DW_CLS_PTR, s.Ranges.Len(), s.Ranges)
s.PutRanges(ctxt, ic.Ranges)
} else {
st := ic.Ranges[0].Start
en := ic.Ranges[0].End
putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, st, s.StartPC)
putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, en, s.StartPC)
}
// Emit call file, line attrs.
ctxt.AddFileRef(s.Info, ic.CallFile)
form := int(expandPseudoForm(DW_FORM_udata_pseudo))
putattr(ctxt, s.Info, abbrev, form, DW_CLS_CONSTANT, int64(ic.CallLine), nil)
// Variables associated with this inlined routine instance.
vars := ic.InlVars
sort.Sort(byChildIndex(vars))
inlIndex := ic.InlIndex
var encbuf [20]byte
for _, v := range vars {
if !v.IsInAbstract {
continue
}
putvar(ctxt, s, v, callee, abbrev, inlIndex, encbuf[:0])
}
// Children of this inline.
for _, sib := range inlChildren(callIdx, &s.InlCalls) {
absfn := s.InlCalls.Calls[sib].AbsFunSym
err := PutInlinedFunc(ctxt, s, absfn, sib)
if err != nil {
return err
}
}
Uleb128put(ctxt, s.Info, 0)
return nil
}
// Emit DWARF attributes and child DIEs for a 'concrete' subprogram,
// meaning the out-of-line copy of a function that was inlined at some
// point during the compilation of its containing package. The first
// attribute for a concrete DIE is a reference to the 'abstract' DIE
// for the function (which holds location-independent attributes such
// as name, type), then the remainder of the attributes are specific
// to this instance (location, frame base, etc).
func PutConcreteFunc(ctxt Context, s *FnState) error {
if logDwarf {
ctxt.Logf("PutConcreteFunc(%v)\n", s.Info)
}
abbrev := DW_ABRV_FUNCTION_CONCRETE
Uleb128put(ctxt, s.Info, int64(abbrev))
// Abstract origin.
putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, s.Absfn)
// Start/end PC.
putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, 0, s.StartPC)
putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, s.Size, s.StartPC)
// cfa / frame base
putattr(ctxt, s.Info, abbrev, DW_FORM_block1, DW_CLS_BLOCK, 1, []byte{DW_OP_call_frame_cfa})
// Scopes
if err := putPrunedScopes(ctxt, s, abbrev); err != nil {
return err
}
// Inlined subroutines.
for _, sib := range inlChildren(-1, &s.InlCalls) {
absfn := s.InlCalls.Calls[sib].AbsFunSym
err := PutInlinedFunc(ctxt, s, absfn, sib)
if err != nil {
return err
}
}
Uleb128put(ctxt, s.Info, 0)
return nil
}
// Emit DWARF attributes and child DIEs for a subprogram. Here
// 'default' implies that the function in question was not inlined
// when its containing package was compiled (hence there is no need to
// emit an abstract version for it to use as a base for inlined
// routine records).
func PutDefaultFunc(ctxt Context, s *FnState) error {
if logDwarf {
ctxt.Logf("PutDefaultFunc(%v)\n", s.Info)
}
abbrev := DW_ABRV_FUNCTION
Uleb128put(ctxt, s.Info, int64(abbrev))
putattr(ctxt, s.Info, DW_ABRV_FUNCTION, DW_FORM_string, DW_CLS_STRING, int64(len(s.Name)), s.Name)
putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, 0, s.StartPC)
putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, s.Size, s.StartPC)
putattr(ctxt, s.Info, abbrev, DW_FORM_block1, DW_CLS_BLOCK, 1, []byte{DW_OP_call_frame_cfa})
ctxt.AddFileRef(s.Info, s.Filesym)
var ev int64
if s.External {
ev = 1
}
putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, ev, 0)
// Scopes
if err := putPrunedScopes(ctxt, s, abbrev); err != nil {
return err
}
// Inlined subroutines.
for _, sib := range inlChildren(-1, &s.InlCalls) {
absfn := s.InlCalls.Calls[sib].AbsFunSym
err := PutInlinedFunc(ctxt, s, absfn, sib)
if err != nil {
return err
}
}
Uleb128put(ctxt, s.Info, 0)
return nil
}
func putscope(ctxt Context, s *FnState, scopes []Scope, curscope int32, fnabbrev int, encbuf []byte) int32 {
if logDwarf {
ctxt.Logf("putscope(%v,%d): vars:", s.Info, curscope)
for i, v := range scopes[curscope].Vars {
ctxt.Logf(" %d:%d:%s", i, v.ChildIndex, v.Name)
}
ctxt.Logf("\n")
}
for _, v := range scopes[curscope].Vars {
putvar(ctxt, s, v, s.Absfn, fnabbrev, -1, encbuf)
}
this := curscope
curscope++
for curscope < int32(len(scopes)) {
scope := scopes[curscope]
if scope.Parent != this {
return curscope
}
if len(scopes[curscope].Vars) == 0 {
curscope = putscope(ctxt, s, scopes, curscope, fnabbrev, encbuf)
continue
}
if len(scope.Ranges) == 1 {
Uleb128put(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_SIMPLE)
putattr(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_SIMPLE, DW_FORM_addr, DW_CLS_ADDRESS, scope.Ranges[0].Start, s.StartPC)
putattr(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_SIMPLE, DW_FORM_addr, DW_CLS_ADDRESS, scope.Ranges[0].End, s.StartPC)
} else {
Uleb128put(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_RANGES)
putattr(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_RANGES, DW_FORM_sec_offset, DW_CLS_PTR, s.Ranges.Len(), s.Ranges)
s.PutRanges(ctxt, scope.Ranges)
}
curscope = putscope(ctxt, s, scopes, curscope, fnabbrev, encbuf)
Uleb128put(ctxt, s.Info, 0)
}
return curscope
}
// Given a default var abbrev code, select corresponding concrete code.
func concreteVarAbbrev(varAbbrev int) int {
switch varAbbrev {
case DW_ABRV_AUTO:
return DW_ABRV_AUTO_CONCRETE
case DW_ABRV_PARAM:
return DW_ABRV_PARAM_CONCRETE
case DW_ABRV_AUTO_LOCLIST:
return DW_ABRV_AUTO_CONCRETE_LOCLIST
case DW_ABRV_PARAM_LOCLIST:
return DW_ABRV_PARAM_CONCRETE_LOCLIST
default:
panic("should never happen")
}
}
// Pick the correct abbrev code for variable or parameter DIE.
func determineVarAbbrev(v *Var, fnabbrev int) (int, bool, bool) {
abbrev := v.Abbrev
// If the variable was entirely optimized out, don't emit a location list;
// convert to an inline abbreviation and emit an empty location.
missing := false
switch {
case abbrev == DW_ABRV_AUTO_LOCLIST && v.PutLocationList == nil:
missing = true
abbrev = DW_ABRV_AUTO
case abbrev == DW_ABRV_PARAM_LOCLIST && v.PutLocationList == nil:
missing = true
abbrev = DW_ABRV_PARAM
}
// Determine whether to use a concrete variable or regular variable DIE.
concrete := true
switch fnabbrev {
case DW_ABRV_FUNCTION:
concrete = false
break
case DW_ABRV_FUNCTION_CONCRETE:
// If we're emitting a concrete subprogram DIE and the variable
// in question is not part of the corresponding abstract function DIE,
// then use the default (non-concrete) abbrev for this param.
if !v.IsInAbstract {
concrete = false
}
case DW_ABRV_INLINED_SUBROUTINE, DW_ABRV_INLINED_SUBROUTINE_RANGES:
default:
panic("should never happen")
}
// Select proper abbrev based on concrete/non-concrete
if concrete {
abbrev = concreteVarAbbrev(abbrev)
}
return abbrev, missing, concrete
}
func abbrevUsesLoclist(abbrev int) bool {
switch abbrev {
case DW_ABRV_AUTO_LOCLIST, DW_ABRV_AUTO_CONCRETE_LOCLIST,
DW_ABRV_PARAM_LOCLIST, DW_ABRV_PARAM_CONCRETE_LOCLIST:
return true
default:
return false
}
}
// Emit DWARF attributes for a variable belonging to an 'abstract' subprogram.
func putAbstractVar(ctxt Context, info Sym, v *Var) {
// Remap abbrev
abbrev := v.Abbrev
switch abbrev {
case DW_ABRV_AUTO, DW_ABRV_AUTO_LOCLIST:
abbrev = DW_ABRV_AUTO_ABSTRACT
case DW_ABRV_PARAM, DW_ABRV_PARAM_LOCLIST:
abbrev = DW_ABRV_PARAM_ABSTRACT
}
Uleb128put(ctxt, info, int64(abbrev))
putattr(ctxt, info, abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(v.Name)), v.Name)
// Isreturn attribute if this is a param
if abbrev == DW_ABRV_PARAM_ABSTRACT {
var isReturn int64
if v.IsReturnValue {
isReturn = 1
}
putattr(ctxt, info, abbrev, DW_FORM_flag, DW_CLS_FLAG, isReturn, nil)
}
// Line
if abbrev != DW_ABRV_PARAM_ABSTRACT {
// See issue 23374 for more on why decl line is skipped for abs params.
putattr(ctxt, info, abbrev, DW_FORM_udata, DW_CLS_CONSTANT, int64(v.DeclLine), nil)
}
// Type
putattr(ctxt, info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, v.Type)
// Var has no children => no terminator
}
func putvar(ctxt Context, s *FnState, v *Var, absfn Sym, fnabbrev, inlIndex int, encbuf []byte) {
// Remap abbrev according to parent DIE abbrev
abbrev, missing, concrete := determineVarAbbrev(v, fnabbrev)
Uleb128put(ctxt, s.Info, int64(abbrev))
// Abstract origin for concrete / inlined case
if concrete {
// Here we are making a reference to a child DIE of an abstract
// function subprogram DIE. The child DIE has no LSym, so instead
// after the call to 'putattr' below we make a call to register
// the child DIE reference.
putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, absfn)
ctxt.RecordDclReference(s.Info, absfn, int(v.ChildIndex), inlIndex)
} else {
// Var name, line for abstract and default cases
n := v.Name
putattr(ctxt, s.Info, abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(n)), n)
if abbrev == DW_ABRV_PARAM || abbrev == DW_ABRV_PARAM_LOCLIST || abbrev == DW_ABRV_PARAM_ABSTRACT {
var isReturn int64
if v.IsReturnValue {
isReturn = 1
}
putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, isReturn, nil)
}
putattr(ctxt, s.Info, abbrev, DW_FORM_udata, DW_CLS_CONSTANT, int64(v.DeclLine), nil)
putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, v.Type)
}
if abbrevUsesLoclist(abbrev) {
putattr(ctxt, s.Info, abbrev, DW_FORM_sec_offset, DW_CLS_PTR, s.Loc.Len(), s.Loc)
v.PutLocationList(s.Loc, s.StartPC)
} else {
loc := encbuf[:0]
switch {
case missing:
break // no location
case v.StackOffset == 0:
loc = append(loc, DW_OP_call_frame_cfa)
default:
loc = append(loc, DW_OP_fbreg)
loc = AppendSleb128(loc, int64(v.StackOffset))
}
putattr(ctxt, s.Info, abbrev, DW_FORM_block1, DW_CLS_BLOCK, int64(len(loc)), loc)
}
// Var has no children => no terminator
}
// VarsByOffset attaches the methods of sort.Interface to []*Var,
// sorting in increasing StackOffset.
type VarsByOffset []*Var
func (s VarsByOffset) Len() int { return len(s) }
func (s VarsByOffset) Less(i, j int) bool { return s[i].StackOffset < s[j].StackOffset }
func (s VarsByOffset) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
// byChildIndex implements sort.Interface for []*dwarf.Var by child index.
type byChildIndex []*Var
func (s byChildIndex) Len() int { return len(s) }
func (s byChildIndex) Less(i, j int) bool { return s[i].ChildIndex < s[j].ChildIndex }
func (s byChildIndex) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
// IsDWARFEnabledOnAIX returns true if DWARF is possible on the
// current extld.
// AIX ld doesn't support DWARF with -bnoobjreorder with version
// prior to 7.2.2.
func IsDWARFEnabledOnAIXLd(extld string) (bool, error) {
out, err := exec.Command(extld, "-Wl,-V").CombinedOutput()
if err != nil {
// The normal output should display ld version and
// then fails because ".main" is not defined:
// ld: 0711-317 ERROR: Undefined symbol: .main
if !bytes.Contains(out, []byte("0711-317")) {
return false, fmt.Errorf("%s -Wl,-V failed: %v\n%s", extld, err, out)
}
}
// gcc -Wl,-V output should be:
// /usr/bin/ld: LD X.X.X(date)
// ...
out = bytes.TrimPrefix(out, []byte("/usr/bin/ld: LD "))
vers := string(bytes.Split(out, []byte("("))[0])
subvers := strings.Split(vers, ".")
if len(subvers) != 3 {
return false, fmt.Errorf("cannot parse %s -Wl,-V (%s): %v\n", extld, out, err)
}
if v, err := strconv.Atoi(subvers[0]); err != nil || v < 7 {
return false, nil
} else if v > 7 {
return true, nil
}
if v, err := strconv.Atoi(subvers[1]); err != nil || v < 2 {
return false, nil
} else if v > 2 {
return true, nil
}
if v, err := strconv.Atoi(subvers[2]); err != nil || v < 2 {
return false, nil
}
return true, nil
}
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