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go/src/cmd/link/internal/ld/dwarf.go

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// Copyright 2010 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.
// TODO/NICETOHAVE:
// - eliminate DW_CLS_ if not used
// - package info in compilation units
// - assign types to their packages
// - gdb uses c syntax, meaning clumsy quoting is needed for go identifiers. eg
// ptype struct '[]uint8' and qualifiers need to be quoted away
// - file:line info for variables
// - make strings a typedef so prettyprinters can see the underlying string type
package ld
import (
"cmd/internal/dwarf"
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/sym"
"fmt"
"log"
"sort"
"strings"
)
type dwctxt struct {
linkctxt *Link
}
func (c dwctxt) PtrSize() int {
return c.linkctxt.Arch.PtrSize
}
func (c dwctxt) AddInt(s dwarf.Sym, size int, i int64) {
ls := s.(*sym.Symbol)
ls.AddUintXX(c.linkctxt.Arch, uint64(i), size)
}
func (c dwctxt) AddBytes(s dwarf.Sym, b []byte) {
ls := s.(*sym.Symbol)
ls.AddBytes(b)
}
func (c dwctxt) AddString(s dwarf.Sym, v string) {
Addstring(s.(*sym.Symbol), v)
}
func (c dwctxt) AddAddress(s dwarf.Sym, data interface{}, value int64) {
if value != 0 {
value -= (data.(*sym.Symbol)).Value
}
s.(*sym.Symbol).AddAddrPlus(c.linkctxt.Arch, data.(*sym.Symbol), value)
}
func (c dwctxt) AddSectionOffset(s dwarf.Sym, size int, t interface{}, ofs int64) {
ls := s.(*sym.Symbol)
switch size {
default:
Errorf(ls, "invalid size %d in adddwarfref\n", size)
fallthrough
case c.linkctxt.Arch.PtrSize:
ls.AddAddr(c.linkctxt.Arch, t.(*sym.Symbol))
case 4:
ls.AddAddrPlus4(t.(*sym.Symbol), 0)
}
r := &ls.R[len(ls.R)-1]
r.Type = objabi.R_ADDROFF
r.Add = ofs
}
func (c dwctxt) AddDWARFAddrSectionOffset(s dwarf.Sym, t interface{}, ofs int64) {
size := 4
if isDwarf64(c.linkctxt) {
size = 8
}
c.AddSectionOffset(s, size, t, ofs)
ls := s.(*sym.Symbol)
ls.R[len(ls.R)-1].Type = objabi.R_DWARFSECREF
}
func (c dwctxt) Logf(format string, args ...interface{}) {
c.linkctxt.Logf(format, args...)
}
// At the moment these interfaces are only used in the compiler.
func (c dwctxt) AddFileRef(s dwarf.Sym, f interface{}) {
panic("should be used only in the compiler")
}
func (c dwctxt) CurrentOffset(s dwarf.Sym) int64 {
panic("should be used only in the compiler")
}
func (c dwctxt) RecordDclReference(s dwarf.Sym, t dwarf.Sym, dclIdx int, inlIndex int) {
panic("should be used only in the compiler")
}
func (c dwctxt) RecordChildDieOffsets(s dwarf.Sym, vars []*dwarf.Var, offsets []int32) {
panic("should be used only in the compiler")
}
func isDwarf64(ctxt *Link) bool {
return ctxt.HeadType == objabi.Haix
}
var gdbscript string
var dwarfp []*sym.Symbol
func writeabbrev(ctxt *Link) *sym.Symbol {
s := ctxt.Syms.Lookup(".debug_abbrev", 0)
s.Type = sym.SDWARFSECT
s.AddBytes(dwarf.GetAbbrev())
return s
}
var dwtypes dwarf.DWDie
func newattr(die *dwarf.DWDie, attr uint16, cls int, value int64, data interface{}) *dwarf.DWAttr {
a := new(dwarf.DWAttr)
a.Link = die.Attr
die.Attr = a
a.Atr = attr
a.Cls = uint8(cls)
a.Value = value
a.Data = data
return a
}
// Each DIE (except the root ones) has at least 1 attribute: its
// name. getattr moves the desired one to the front so
// frequently searched ones are found faster.
func getattr(die *dwarf.DWDie, attr uint16) *dwarf.DWAttr {
if die.Attr.Atr == attr {
return die.Attr
}
a := die.Attr
b := a.Link
for b != nil {
if b.Atr == attr {
a.Link = b.Link
b.Link = die.Attr
die.Attr = b
return b
}
a = b
b = b.Link
}
return nil
}
// Every DIE manufactured by the linker has at least an AT_name
// attribute (but it will only be written out if it is listed in the abbrev).
// The compiler does create nameless DWARF DIEs (ex: concrete subprogram
// instance).
func newdie(ctxt *Link, parent *dwarf.DWDie, abbrev int, name string, version int) *dwarf.DWDie {
die := new(dwarf.DWDie)
die.Abbrev = abbrev
die.Link = parent.Child
parent.Child = die
newattr(die, dwarf.DW_AT_name, dwarf.DW_CLS_STRING, int64(len(name)), name)
if name != "" && (abbrev <= dwarf.DW_ABRV_VARIABLE || abbrev >= dwarf.DW_ABRV_NULLTYPE) {
if abbrev != dwarf.DW_ABRV_VARIABLE || version == 0 {
if abbrev == dwarf.DW_ABRV_COMPUNIT {
// Avoid collisions with "real" symbol names.
name = ".pkg." + name
}
s := ctxt.Syms.Lookup(dwarf.InfoPrefix+name, version)
s.Attr |= sym.AttrNotInSymbolTable
s.Type = sym.SDWARFINFO
die.Sym = s
}
}
return die
}
func walktypedef(die *dwarf.DWDie) *dwarf.DWDie {
if die == nil {
return nil
}
// Resolve typedef if present.
if die.Abbrev == dwarf.DW_ABRV_TYPEDECL {
for attr := die.Attr; attr != nil; attr = attr.Link {
if attr.Atr == dwarf.DW_AT_type && attr.Cls == dwarf.DW_CLS_REFERENCE && attr.Data != nil {
return attr.Data.(*dwarf.DWDie)
}
}
}
return die
}
func walksymtypedef(ctxt *Link, s *sym.Symbol) *sym.Symbol {
if t := ctxt.Syms.ROLookup(s.Name+"..def", int(s.Version)); t != nil {
return t
}
return s
}
// Find child by AT_name using hashtable if available or linear scan
// if not.
func findchild(die *dwarf.DWDie, name string) *dwarf.DWDie {
var prev *dwarf.DWDie
for ; die != prev; prev, die = die, walktypedef(die) {
for a := die.Child; a != nil; a = a.Link {
if name == getattr(a, dwarf.DW_AT_name).Data {
return a
}
}
continue
}
return nil
}
// Used to avoid string allocation when looking up dwarf symbols
var prefixBuf = []byte(dwarf.InfoPrefix)
func find(ctxt *Link, name string) *sym.Symbol {
n := append(prefixBuf, name...)
// The string allocation below is optimized away because it is only used in a map lookup.
s := ctxt.Syms.ROLookup(string(n), 0)
prefixBuf = n[:len(dwarf.InfoPrefix)]
if s != nil && s.Type == sym.SDWARFINFO {
return s
}
return nil
}
func mustFind(ctxt *Link, name string) *sym.Symbol {
r := find(ctxt, name)
if r == nil {
Exitf("dwarf find: cannot find %s", name)
}
return r
}
func adddwarfref(ctxt *Link, s *sym.Symbol, t *sym.Symbol, size int) int64 {
var result int64
switch size {
default:
Errorf(s, "invalid size %d in adddwarfref\n", size)
fallthrough
case ctxt.Arch.PtrSize:
result = s.AddAddr(ctxt.Arch, t)
case 4:
result = s.AddAddrPlus4(t, 0)
}
r := &s.R[len(s.R)-1]
r.Type = objabi.R_DWARFSECREF
return result
}
func newrefattr(die *dwarf.DWDie, attr uint16, ref *sym.Symbol) *dwarf.DWAttr {
if ref == nil {
return nil
}
return newattr(die, attr, dwarf.DW_CLS_REFERENCE, 0, ref)
}
func dtolsym(s dwarf.Sym) *sym.Symbol {
if s == nil {
return nil
}
return s.(*sym.Symbol)
}
func putdie(linkctxt *Link, ctxt dwarf.Context, syms []*sym.Symbol, die *dwarf.DWDie) []*sym.Symbol {
s := dtolsym(die.Sym)
if s == nil {
s = syms[len(syms)-1]
} else {
if s.Attr.OnList() {
log.Fatalf("symbol %s listed multiple times", s.Name)
}
s.Attr |= sym.AttrOnList
syms = append(syms, s)
}
dwarf.Uleb128put(ctxt, s, int64(die.Abbrev))
dwarf.PutAttrs(ctxt, s, die.Abbrev, die.Attr)
if dwarf.HasChildren(die) {
for die := die.Child; die != nil; die = die.Link {
syms = putdie(linkctxt, ctxt, syms, die)
}
syms[len(syms)-1].AddUint8(0)
}
return syms
}
func reverselist(list **dwarf.DWDie) {
curr := *list
var prev *dwarf.DWDie
for curr != nil {
next := curr.Link
curr.Link = prev
prev = curr
curr = next
}
*list = prev
}
func reversetree(list **dwarf.DWDie) {
reverselist(list)
for die := *list; die != nil; die = die.Link {
if dwarf.HasChildren(die) {
reversetree(&die.Child)
}
}
}
func newmemberoffsetattr(die *dwarf.DWDie, offs int32) {
newattr(die, dwarf.DW_AT_data_member_location, dwarf.DW_CLS_CONSTANT, int64(offs), nil)
}
// GDB doesn't like FORM_addr for AT_location, so emit a
// location expression that evals to a const.
func newabslocexprattr(die *dwarf.DWDie, addr int64, sym *sym.Symbol) {
newattr(die, dwarf.DW_AT_location, dwarf.DW_CLS_ADDRESS, addr, sym)
// below
}
// Lookup predefined types
func lookupOrDiag(ctxt *Link, n string) *sym.Symbol {
s := ctxt.Syms.ROLookup(n, 0)
if s == nil || s.Size == 0 {
Exitf("dwarf: missing type: %s", n)
}
return s
}
// dwarfFuncSym looks up a DWARF metadata symbol for function symbol s.
// If the symbol does not exist, it creates it if create is true,
// or returns nil otherwise.
func dwarfFuncSym(ctxt *Link, s *sym.Symbol, meta string, create bool) *sym.Symbol {
// All function ABIs use symbol version 0 for the DWARF data.
//
// TODO(austin): It may be useful to have DWARF info for ABI
// wrappers, in which case we may want these versions to
// align. Better yet, replace these name lookups with a
// general way to attach metadata to a symbol.
ver := 0
if s.IsFileLocal() {
ver = int(s.Version)
}
if create {
return ctxt.Syms.Lookup(meta+s.Name, ver)
}
return ctxt.Syms.ROLookup(meta+s.Name, ver)
}
func dotypedef(ctxt *Link, parent *dwarf.DWDie, name string, def *dwarf.DWDie) *dwarf.DWDie {
// Only emit typedefs for real names.
if strings.HasPrefix(name, "map[") {
return nil
}
if strings.HasPrefix(name, "struct {") {
return nil
}
if strings.HasPrefix(name, "chan ") {
return nil
}
if name[0] == '[' || name[0] == '*' {
return nil
}
if def == nil {
Errorf(nil, "dwarf: bad def in dotypedef")
}
s := ctxt.Syms.Lookup(dtolsym(def.Sym).Name+"..def", 0)
s.Attr |= sym.AttrNotInSymbolTable
s.Type = sym.SDWARFINFO
def.Sym = s
// The typedef entry must be created after the def,
// so that future lookups will find the typedef instead
// of the real definition. This hooks the typedef into any
// circular definition loops, so that gdb can understand them.
die := newdie(ctxt, parent, dwarf.DW_ABRV_TYPEDECL, name, 0)
newrefattr(die, dwarf.DW_AT_type, s)
return die
}
// Define gotype, for composite ones recurse into constituents.
func defgotype(ctxt *Link, gotype *sym.Symbol) *sym.Symbol {
if gotype == nil {
return mustFind(ctxt, "<unspecified>")
}
if !strings.HasPrefix(gotype.Name, "type.") {
Errorf(gotype, "dwarf: type name doesn't start with \"type.\"")
return mustFind(ctxt, "<unspecified>")
}
name := gotype.Name[5:] // could also decode from Type.string
sdie := find(ctxt, name)
if sdie != nil {
return sdie
}
return newtype(ctxt, gotype).Sym.(*sym.Symbol)
}
func newtype(ctxt *Link, gotype *sym.Symbol) *dwarf.DWDie {
name := gotype.Name[5:] // could also decode from Type.string
kind := decodetypeKind(ctxt.Arch, gotype)
bytesize := decodetypeSize(ctxt.Arch, gotype)
var die, typedefdie *dwarf.DWDie
switch kind {
case objabi.KindBool:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BASETYPE, name, 0)
newattr(die, dwarf.DW_AT_encoding, dwarf.DW_CLS_CONSTANT, dwarf.DW_ATE_boolean, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
case objabi.KindInt,
objabi.KindInt8,
objabi.KindInt16,
objabi.KindInt32,
objabi.KindInt64:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BASETYPE, name, 0)
newattr(die, dwarf.DW_AT_encoding, dwarf.DW_CLS_CONSTANT, dwarf.DW_ATE_signed, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
case objabi.KindUint,
objabi.KindUint8,
objabi.KindUint16,
objabi.KindUint32,
objabi.KindUint64,
objabi.KindUintptr:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BASETYPE, name, 0)
newattr(die, dwarf.DW_AT_encoding, dwarf.DW_CLS_CONSTANT, dwarf.DW_ATE_unsigned, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
case objabi.KindFloat32,
objabi.KindFloat64:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BASETYPE, name, 0)
newattr(die, dwarf.DW_AT_encoding, dwarf.DW_CLS_CONSTANT, dwarf.DW_ATE_float, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
case objabi.KindComplex64,
objabi.KindComplex128:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BASETYPE, name, 0)
newattr(die, dwarf.DW_AT_encoding, dwarf.DW_CLS_CONSTANT, dwarf.DW_ATE_complex_float, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
case objabi.KindArray:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_ARRAYTYPE, name, 0)
typedefdie = dotypedef(ctxt, &dwtypes, name, die)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
s := decodetypeArrayElem(ctxt.Arch, gotype)
newrefattr(die, dwarf.DW_AT_type, defgotype(ctxt, s))
fld := newdie(ctxt, die, dwarf.DW_ABRV_ARRAYRANGE, "range", 0)
// use actual length not upper bound; correct for 0-length arrays.
newattr(fld, dwarf.DW_AT_count, dwarf.DW_CLS_CONSTANT, decodetypeArrayLen(ctxt.Arch, gotype), 0)
newrefattr(fld, dwarf.DW_AT_type, mustFind(ctxt, "uintptr"))
case objabi.KindChan:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_CHANTYPE, name, 0)
s := decodetypeChanElem(ctxt.Arch, gotype)
newrefattr(die, dwarf.DW_AT_go_elem, defgotype(ctxt, s))
// Save elem type for synthesizechantypes. We could synthesize here
// but that would change the order of DIEs we output.
newrefattr(die, dwarf.DW_AT_type, s)
case objabi.KindFunc:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_FUNCTYPE, name, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
typedefdie = dotypedef(ctxt, &dwtypes, name, die)
nfields := decodetypeFuncInCount(ctxt.Arch, gotype)
for i := 0; i < nfields; i++ {
s := decodetypeFuncInType(ctxt.Arch, gotype, i)
fld := newdie(ctxt, die, dwarf.DW_ABRV_FUNCTYPEPARAM, s.Name[5:], 0)
newrefattr(fld, dwarf.DW_AT_type, defgotype(ctxt, s))
}
if decodetypeFuncDotdotdot(ctxt.Arch, gotype) {
newdie(ctxt, die, dwarf.DW_ABRV_DOTDOTDOT, "...", 0)
}
nfields = decodetypeFuncOutCount(ctxt.Arch, gotype)
for i := 0; i < nfields; i++ {
s := decodetypeFuncOutType(ctxt.Arch, gotype, i)
fld := newdie(ctxt, die, dwarf.DW_ABRV_FUNCTYPEPARAM, s.Name[5:], 0)
newrefattr(fld, dwarf.DW_AT_type, defptrto(ctxt, defgotype(ctxt, s)))
}
case objabi.KindInterface:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_IFACETYPE, name, 0)
typedefdie = dotypedef(ctxt, &dwtypes, name, die)
nfields := int(decodetypeIfaceMethodCount(ctxt.Arch, gotype))
var s *sym.Symbol
if nfields == 0 {
s = lookupOrDiag(ctxt, "type.runtime.eface")
} else {
s = lookupOrDiag(ctxt, "type.runtime.iface")
}
newrefattr(die, dwarf.DW_AT_type, defgotype(ctxt, s))
case objabi.KindMap:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_MAPTYPE, name, 0)
s := decodetypeMapKey(ctxt.Arch, gotype)
newrefattr(die, dwarf.DW_AT_go_key, defgotype(ctxt, s))
s = decodetypeMapValue(ctxt.Arch, gotype)
newrefattr(die, dwarf.DW_AT_go_elem, defgotype(ctxt, s))
// Save gotype for use in synthesizemaptypes. We could synthesize here,
// but that would change the order of the DIEs.
newrefattr(die, dwarf.DW_AT_type, gotype)
case objabi.KindPtr:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_PTRTYPE, name, 0)
typedefdie = dotypedef(ctxt, &dwtypes, name, die)
s := decodetypePtrElem(ctxt.Arch, gotype)
newrefattr(die, dwarf.DW_AT_type, defgotype(ctxt, s))
case objabi.KindSlice:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_SLICETYPE, name, 0)
typedefdie = dotypedef(ctxt, &dwtypes, name, die)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
s := decodetypeArrayElem(ctxt.Arch, gotype)
elem := defgotype(ctxt, s)
newrefattr(die, dwarf.DW_AT_go_elem, elem)
case objabi.KindString:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_STRINGTYPE, name, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
case objabi.KindStruct:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_STRUCTTYPE, name, 0)
typedefdie = dotypedef(ctxt, &dwtypes, name, die)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
nfields := decodetypeStructFieldCount(ctxt.Arch, gotype)
for i := 0; i < nfields; i++ {
f := decodetypeStructFieldName(ctxt.Arch, gotype, i)
s := decodetypeStructFieldType(ctxt.Arch, gotype, i)
if f == "" {
f = s.Name[5:] // skip "type."
}
fld := newdie(ctxt, die, dwarf.DW_ABRV_STRUCTFIELD, f, 0)
newrefattr(fld, dwarf.DW_AT_type, defgotype(ctxt, s))
offsetAnon := decodetypeStructFieldOffsAnon(ctxt.Arch, gotype, i)
newmemberoffsetattr(fld, int32(offsetAnon>>1))
if offsetAnon&1 != 0 { // is embedded field
newattr(fld, dwarf.DW_AT_go_embedded_field, dwarf.DW_CLS_FLAG, 1, 0)
}
}
case objabi.KindUnsafePointer:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BARE_PTRTYPE, name, 0)
default:
Errorf(gotype, "dwarf: definition of unknown kind %d", kind)
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_TYPEDECL, name, 0)
newrefattr(die, dwarf.DW_AT_type, mustFind(ctxt, "<unspecified>"))
}
newattr(die, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, int64(kind), 0)
if gotype.Attr.Reachable() {
newattr(die, dwarf.DW_AT_go_runtime_type, dwarf.DW_CLS_GO_TYPEREF, 0, gotype)
}
if _, ok := prototypedies[gotype.Name]; ok {
prototypedies[gotype.Name] = die
}
if typedefdie != nil {
return typedefdie
}
return die
}
func nameFromDIESym(dwtype *sym.Symbol) string {
return strings.TrimSuffix(dwtype.Name[len(dwarf.InfoPrefix):], "..def")
}
// Find or construct *T given T.
func defptrto(ctxt *Link, dwtype *sym.Symbol) *sym.Symbol {
ptrname := "*" + nameFromDIESym(dwtype)
if die := find(ctxt, ptrname); die != nil {
return die
}
pdie := newdie(ctxt, &dwtypes, dwarf.DW_ABRV_PTRTYPE, ptrname, 0)
newrefattr(pdie, dwarf.DW_AT_type, dwtype)
// The DWARF info synthesizes pointer types that don't exist at the
// language level, like *hash<...> and *bucket<...>, and the data
// pointers of slices. Link to the ones we can find.
gotype := ctxt.Syms.ROLookup("type."+ptrname, 0)
if gotype != nil && gotype.Attr.Reachable() {
newattr(pdie, dwarf.DW_AT_go_runtime_type, dwarf.DW_CLS_GO_TYPEREF, 0, gotype)
}
return dtolsym(pdie.Sym)
}
// Copies src's children into dst. Copies attributes by value.
// DWAttr.data is copied as pointer only. If except is one of
// the top-level children, it will not be copied.
func copychildrenexcept(ctxt *Link, dst *dwarf.DWDie, src *dwarf.DWDie, except *dwarf.DWDie) {
for src = src.Child; src != nil; src = src.Link {
if src == except {
continue
}
c := newdie(ctxt, dst, src.Abbrev, getattr(src, dwarf.DW_AT_name).Data.(string), 0)
for a := src.Attr; a != nil; a = a.Link {
newattr(c, a.Atr, int(a.Cls), a.Value, a.Data)
}
copychildrenexcept(ctxt, c, src, nil)
}
reverselist(&dst.Child)
}
func copychildren(ctxt *Link, dst *dwarf.DWDie, src *dwarf.DWDie) {
copychildrenexcept(ctxt, dst, src, nil)
}
// Search children (assumed to have TAG_member) for the one named
// field and set its AT_type to dwtype
func substitutetype(structdie *dwarf.DWDie, field string, dwtype *sym.Symbol) {
child := findchild(structdie, field)
if child == nil {
Exitf("dwarf substitutetype: %s does not have member %s",
getattr(structdie, dwarf.DW_AT_name).Data, field)
return
}
a := getattr(child, dwarf.DW_AT_type)
if a != nil {
a.Data = dwtype
} else {
newrefattr(child, dwarf.DW_AT_type, dwtype)
}
}
func findprotodie(ctxt *Link, name string) *dwarf.DWDie {
die, ok := prototypedies[name]
if ok && die == nil {
defgotype(ctxt, lookupOrDiag(ctxt, name))
die = prototypedies[name]
}
return die
}
func synthesizestringtypes(ctxt *Link, die *dwarf.DWDie) {
prototype := walktypedef(findprotodie(ctxt, "type.runtime.stringStructDWARF"))
if prototype == nil {
return
}
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_STRINGTYPE {
continue
}
copychildren(ctxt, die, prototype)
}
}
func synthesizeslicetypes(ctxt *Link, die *dwarf.DWDie) {
prototype := walktypedef(findprotodie(ctxt, "type.runtime.slice"))
if prototype == nil {
return
}
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_SLICETYPE {
continue
}
copychildren(ctxt, die, prototype)
elem := getattr(die, dwarf.DW_AT_go_elem).Data.(*sym.Symbol)
substitutetype(die, "array", defptrto(ctxt, elem))
}
}
func mkinternaltypename(base string, arg1 string, arg2 string) string {
if arg2 == "" {
return fmt.Sprintf("%s<%s>", base, arg1)
}
return fmt.Sprintf("%s<%s,%s>", base, arg1, arg2)
}
// synthesizemaptypes is way too closely married to runtime/hashmap.c
const (
MaxKeySize = 128
MaxValSize = 128
BucketSize = 8
)
func mkinternaltype(ctxt *Link, abbrev int, typename, keyname, valname string, f func(*dwarf.DWDie)) *sym.Symbol {
name := mkinternaltypename(typename, keyname, valname)
symname := dwarf.InfoPrefix + name
s := ctxt.Syms.ROLookup(symname, 0)
if s != nil && s.Type == sym.SDWARFINFO {
return s
}
die := newdie(ctxt, &dwtypes, abbrev, name, 0)
f(die)
return dtolsym(die.Sym)
}
func synthesizemaptypes(ctxt *Link, die *dwarf.DWDie) {
hash := walktypedef(findprotodie(ctxt, "type.runtime.hmap"))
bucket := walktypedef(findprotodie(ctxt, "type.runtime.bmap"))
if hash == nil {
return
}
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_MAPTYPE {
continue
}
gotype := getattr(die, dwarf.DW_AT_type).Data.(*sym.Symbol)
keytype := decodetypeMapKey(ctxt.Arch, gotype)
valtype := decodetypeMapValue(ctxt.Arch, gotype)
keysize, valsize := decodetypeSize(ctxt.Arch, keytype), decodetypeSize(ctxt.Arch, valtype)
keytype, valtype = walksymtypedef(ctxt, defgotype(ctxt, keytype)), walksymtypedef(ctxt, defgotype(ctxt, valtype))
// compute size info like hashmap.c does.
indirectKey, indirectVal := false, false
if keysize > MaxKeySize {
keysize = int64(ctxt.Arch.PtrSize)
indirectKey = true
}
if valsize > MaxValSize {
valsize = int64(ctxt.Arch.PtrSize)
indirectVal = true
}
// Construct type to represent an array of BucketSize keys
keyname := nameFromDIESym(keytype)
dwhks := mkinternaltype(ctxt, dwarf.DW_ABRV_ARRAYTYPE, "[]key", keyname, "", func(dwhk *dwarf.DWDie) {
newattr(dwhk, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, BucketSize*keysize, 0)
t := keytype
if indirectKey {
t = defptrto(ctxt, keytype)
}
newrefattr(dwhk, dwarf.DW_AT_type, t)
fld := newdie(ctxt, dwhk, dwarf.DW_ABRV_ARRAYRANGE, "size", 0)
newattr(fld, dwarf.DW_AT_count, dwarf.DW_CLS_CONSTANT, BucketSize, 0)
newrefattr(fld, dwarf.DW_AT_type, mustFind(ctxt, "uintptr"))
})
// Construct type to represent an array of BucketSize values
valname := nameFromDIESym(valtype)
dwhvs := mkinternaltype(ctxt, dwarf.DW_ABRV_ARRAYTYPE, "[]val", valname, "", func(dwhv *dwarf.DWDie) {
newattr(dwhv, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, BucketSize*valsize, 0)
t := valtype
if indirectVal {
t = defptrto(ctxt, valtype)
}
newrefattr(dwhv, dwarf.DW_AT_type, t)
fld := newdie(ctxt, dwhv, dwarf.DW_ABRV_ARRAYRANGE, "size", 0)
newattr(fld, dwarf.DW_AT_count, dwarf.DW_CLS_CONSTANT, BucketSize, 0)
newrefattr(fld, dwarf.DW_AT_type, mustFind(ctxt, "uintptr"))
})
// Construct bucket<K,V>
dwhbs := mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "bucket", keyname, valname, func(dwhb *dwarf.DWDie) {
// Copy over all fields except the field "data" from the generic
// bucket. "data" will be replaced with keys/values below.
copychildrenexcept(ctxt, dwhb, bucket, findchild(bucket, "data"))
fld := newdie(ctxt, dwhb, dwarf.DW_ABRV_STRUCTFIELD, "keys", 0)
newrefattr(fld, dwarf.DW_AT_type, dwhks)
newmemberoffsetattr(fld, BucketSize)
fld = newdie(ctxt, dwhb, dwarf.DW_ABRV_STRUCTFIELD, "values", 0)
newrefattr(fld, dwarf.DW_AT_type, dwhvs)
newmemberoffsetattr(fld, BucketSize+BucketSize*int32(keysize))
fld = newdie(ctxt, dwhb, dwarf.DW_ABRV_STRUCTFIELD, "overflow", 0)
newrefattr(fld, dwarf.DW_AT_type, defptrto(ctxt, dtolsym(dwhb.Sym)))
newmemberoffsetattr(fld, BucketSize+BucketSize*(int32(keysize)+int32(valsize)))
if ctxt.Arch.RegSize > ctxt.Arch.PtrSize {
fld = newdie(ctxt, dwhb, dwarf.DW_ABRV_STRUCTFIELD, "pad", 0)
newrefattr(fld, dwarf.DW_AT_type, mustFind(ctxt, "uintptr"))
newmemberoffsetattr(fld, BucketSize+BucketSize*(int32(keysize)+int32(valsize))+int32(ctxt.Arch.PtrSize))
}
newattr(dwhb, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, BucketSize+BucketSize*keysize+BucketSize*valsize+int64(ctxt.Arch.RegSize), 0)
})
// Construct hash<K,V>
dwhs := mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "hash", keyname, valname, func(dwh *dwarf.DWDie) {
copychildren(ctxt, dwh, hash)
substitutetype(dwh, "buckets", defptrto(ctxt, dwhbs))
substitutetype(dwh, "oldbuckets", defptrto(ctxt, dwhbs))
newattr(dwh, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(hash, dwarf.DW_AT_byte_size).Value, nil)
})
// make map type a pointer to hash<K,V>
newrefattr(die, dwarf.DW_AT_type, defptrto(ctxt, dwhs))
}
}
func synthesizechantypes(ctxt *Link, die *dwarf.DWDie) {
sudog := walktypedef(findprotodie(ctxt, "type.runtime.sudog"))
waitq := walktypedef(findprotodie(ctxt, "type.runtime.waitq"))
hchan := walktypedef(findprotodie(ctxt, "type.runtime.hchan"))
if sudog == nil || waitq == nil || hchan == nil {
return
}
sudogsize := int(getattr(sudog, dwarf.DW_AT_byte_size).Value)
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_CHANTYPE {
continue
}
elemgotype := getattr(die, dwarf.DW_AT_type).Data.(*sym.Symbol)
elemname := elemgotype.Name[5:]
elemtype := walksymtypedef(ctxt, defgotype(ctxt, elemgotype))
// sudog<T>
dwss := mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "sudog", elemname, "", func(dws *dwarf.DWDie) {
copychildren(ctxt, dws, sudog)
substitutetype(dws, "elem", defptrto(ctxt, elemtype))
newattr(dws, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, int64(sudogsize), nil)
})
// waitq<T>
dwws := mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "waitq", elemname, "", func(dww *dwarf.DWDie) {
copychildren(ctxt, dww, waitq)
substitutetype(dww, "first", defptrto(ctxt, dwss))
substitutetype(dww, "last", defptrto(ctxt, dwss))
newattr(dww, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(waitq, dwarf.DW_AT_byte_size).Value, nil)
})
// hchan<T>
dwhs := mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "hchan", elemname, "", func(dwh *dwarf.DWDie) {
copychildren(ctxt, dwh, hchan)
substitutetype(dwh, "recvq", dwws)
substitutetype(dwh, "sendq", dwws)
newattr(dwh, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(hchan, dwarf.DW_AT_byte_size).Value, nil)
})
newrefattr(die, dwarf.DW_AT_type, defptrto(ctxt, dwhs))
}
}
func dwarfDefineGlobal(ctxt *Link, s *sym.Symbol, str string, v int64, gotype *sym.Symbol) {
lib := s.Lib
if lib == nil {
lib = ctxt.LibraryByPkg["runtime"]
}
dv := newdie(ctxt, ctxt.compUnitByPackage[lib].dwinfo, dwarf.DW_ABRV_VARIABLE, str, int(s.Version))
newabslocexprattr(dv, v, s)
if !s.IsFileLocal() {
newattr(dv, dwarf.DW_AT_external, dwarf.DW_CLS_FLAG, 1, 0)
}
dt := defgotype(ctxt, gotype)
newrefattr(dv, dwarf.DW_AT_type, dt)
}
// For use with pass.c::genasmsym
func defdwsymb(ctxt *Link, s *sym.Symbol, str string, t SymbolType, v int64, gotype *sym.Symbol) {
if strings.HasPrefix(str, "go.string.") {
return
}
if strings.HasPrefix(str, "runtime.gcbits.") {
return
}
switch t {
case DataSym, BSSSym:
switch s.Type {
case sym.SDATA, sym.SNOPTRDATA, sym.STYPE, sym.SBSS, sym.SNOPTRBSS, sym.STLSBSS:
// ok
case sym.SRODATA:
if gotype != nil {
defgotype(ctxt, gotype)
}
return
default:
return
}
if ctxt.LinkMode != LinkExternal && isStaticTemp(s.Name) {
return
}
dwarfDefineGlobal(ctxt, s, str, v, gotype)
case AutoSym, ParamSym, DeletedAutoSym:
defgotype(ctxt, gotype)
}
}
// createUnitLength creates the initial length field with value v and update
// offset of unit_length if needed.
func createUnitLength(ctxt *Link, s *sym.Symbol, v uint64) {
if isDwarf64(ctxt) {
s.AddUint32(ctxt.Arch, 0xFFFFFFFF)
}
addDwarfAddrField(ctxt, s, v)
}
// addDwarfAddrField adds a DWARF field in DWARF 64bits or 32bits.
func addDwarfAddrField(ctxt *Link, s *sym.Symbol, v uint64) {
if isDwarf64(ctxt) {
s.AddUint(ctxt.Arch, v)
} else {
s.AddUint32(ctxt.Arch, uint32(v))
}
}
// addDwarfAddrRef adds a DWARF pointer in DWARF 64bits or 32bits.
func addDwarfAddrRef(ctxt *Link, s *sym.Symbol, t *sym.Symbol) {
if isDwarf64(ctxt) {
adddwarfref(ctxt, s, t, 8)
} else {
adddwarfref(ctxt, s, t, 4)
}
}
// compilationUnit is per-compilation unit (equivalently, per-package)
// debug-related data.
type compilationUnit struct {
lib *sym.Library
consts *sym.Symbol // Package constants DIEs
pcs []dwarf.Range // PC ranges, relative to textp[0]
dwinfo *dwarf.DWDie // CU root DIE
funcDIEs []*sym.Symbol // Function DIE subtrees
absFnDIEs []*sym.Symbol // Abstract function DIE subtrees
rangeSyms []*sym.Symbol // symbols for debug_range
}
// calcCompUnitRanges calculates the PC ranges of the compilation units.
func calcCompUnitRanges(ctxt *Link) {
var prevUnit *compilationUnit
for _, s := range ctxt.Textp {
if s.FuncInfo == nil {
continue
}
unit := ctxt.compUnitByPackage[s.Lib]
// Update PC ranges.
//
// We don't simply compare the end of the previous
// symbol with the start of the next because there's
// often a little padding between them. Instead, we
// only create boundaries between symbols from
// different units.
if prevUnit != unit {
unit.pcs = append(unit.pcs, dwarf.Range{Start: s.Value - unit.lib.Textp[0].Value})
prevUnit = unit
}
unit.pcs[len(unit.pcs)-1].End = s.Value - unit.lib.Textp[0].Value + s.Size
}
}
func movetomodule(ctxt *Link, parent *dwarf.DWDie) {
runtimelib := ctxt.LibraryByPkg["runtime"]
die := ctxt.compUnitByPackage[runtimelib].dwinfo.Child
if die == nil {
ctxt.compUnitByPackage[runtimelib].dwinfo.Child = parent.Child
return
}
for die.Link != nil {
die = die.Link
}
die.Link = parent.Child
}
// If the pcln table contains runtime/proc.go, use that to set gdbscript path.
func finddebugruntimepath(s *sym.Symbol) {
if gdbscript != "" {
return
}
for i := range s.FuncInfo.File {
f := s.FuncInfo.File[i]
// We can't use something that may be dead-code
// eliminated from a binary here. proc.go contains
// main and the scheduler, so it's not going anywhere.
if i := strings.Index(f.Name, "runtime/proc.go"); i >= 0 {
gdbscript = f.Name[:i] + "runtime/runtime-gdb.py"
break
}
}
}
/*
* Generate a sequence of opcodes that is as short as possible.
* See section 6.2.5
*/
const (
LINE_BASE = -4
LINE_RANGE = 10
PC_RANGE = (255 - OPCODE_BASE) / LINE_RANGE
OPCODE_BASE = 11
)
func putpclcdelta(linkctxt *Link, ctxt dwarf.Context, s *sym.Symbol, deltaPC uint64, deltaLC int64) {
// Choose a special opcode that minimizes the number of bytes needed to
// encode the remaining PC delta and LC delta.
var opcode int64
if deltaLC < LINE_BASE {
if deltaPC >= PC_RANGE {
opcode = OPCODE_BASE + (LINE_RANGE * PC_RANGE)
} else {
opcode = OPCODE_BASE + (LINE_RANGE * int64(deltaPC))
}
} else if deltaLC < LINE_BASE+LINE_RANGE {
if deltaPC >= PC_RANGE {
opcode = OPCODE_BASE + (deltaLC - LINE_BASE) + (LINE_RANGE * PC_RANGE)
if opcode > 255 {
opcode -= LINE_RANGE
}
} else {
opcode = OPCODE_BASE + (deltaLC - LINE_BASE) + (LINE_RANGE * int64(deltaPC))
}
} else {
if deltaPC <= PC_RANGE {
opcode = OPCODE_BASE + (LINE_RANGE - 1) + (LINE_RANGE * int64(deltaPC))
if opcode > 255 {
opcode = 255
}
} else {
// Use opcode 249 (pc+=23, lc+=5) or 255 (pc+=24, lc+=1).
//
// Let x=deltaPC-PC_RANGE. If we use opcode 255, x will be the remaining
// deltaPC that we need to encode separately before emitting 255. If we
// use opcode 249, we will need to encode x+1. If x+1 takes one more
// byte to encode than x, then we use opcode 255.
//
// In all other cases x and x+1 take the same number of bytes to encode,
// so we use opcode 249, which may save us a byte in encoding deltaLC,
// for similar reasons.
switch deltaPC - PC_RANGE {
// PC_RANGE is the largest deltaPC we can encode in one byte, using
// DW_LNS_const_add_pc.
//
// (1<<16)-1 is the largest deltaPC we can encode in three bytes, using
// DW_LNS_fixed_advance_pc.
//
// (1<<(7n))-1 is the largest deltaPC we can encode in n+1 bytes for
// n=1,3,4,5,..., using DW_LNS_advance_pc.
case PC_RANGE, (1 << 7) - 1, (1 << 16) - 1, (1 << 21) - 1, (1 << 28) - 1,
(1 << 35) - 1, (1 << 42) - 1, (1 << 49) - 1, (1 << 56) - 1, (1 << 63) - 1:
opcode = 255
default:
opcode = OPCODE_BASE + LINE_RANGE*PC_RANGE - 1 // 249
}
}
}
if opcode < OPCODE_BASE || opcode > 255 {
panic(fmt.Sprintf("produced invalid special opcode %d", opcode))
}
// Subtract from deltaPC and deltaLC the amounts that the opcode will add.
deltaPC -= uint64((opcode - OPCODE_BASE) / LINE_RANGE)
deltaLC -= (opcode-OPCODE_BASE)%LINE_RANGE + LINE_BASE
// Encode deltaPC.
if deltaPC != 0 {
if deltaPC <= PC_RANGE {
// Adjust the opcode so that we can use the 1-byte DW_LNS_const_add_pc
// instruction.
opcode -= LINE_RANGE * int64(PC_RANGE-deltaPC)
if opcode < OPCODE_BASE {
panic(fmt.Sprintf("produced invalid special opcode %d", opcode))
}
s.AddUint8(dwarf.DW_LNS_const_add_pc)
} else if (1<<14) <= deltaPC && deltaPC < (1<<16) {
s.AddUint8(dwarf.DW_LNS_fixed_advance_pc)
s.AddUint16(linkctxt.Arch, uint16(deltaPC))
} else {
s.AddUint8(dwarf.DW_LNS_advance_pc)
dwarf.Uleb128put(ctxt, s, int64(deltaPC))
}
}
// Encode deltaLC.
if deltaLC != 0 {
s.AddUint8(dwarf.DW_LNS_advance_line)
dwarf.Sleb128put(ctxt, s, deltaLC)
}
// Output the special opcode.
s.AddUint8(uint8(opcode))
}
/*
* Walk prog table, emit line program and build DIE tree.
*/
func getCompilationDir() string {
// OSX requires this be set to something, but it's not easy to choose
// a value. Linking takes place in a temporary directory, so there's
// no point including it here. Paths in the file table are usually
// absolute, in which case debuggers will ignore this value. -trimpath
// produces relative paths, but we don't know where they start, so
// all we can do here is try not to make things worse.
return "."
}
func importInfoSymbol(ctxt *Link, dsym *sym.Symbol) {
dsym.Attr |= sym.AttrNotInSymbolTable | sym.AttrReachable
dsym.Type = sym.SDWARFINFO
for i := range dsym.R {
r := &dsym.R[i] // Copying sym.Reloc has measurable impact on performance
if r.Type == objabi.R_DWARFSECREF && r.Sym.Size == 0 {
n := nameFromDIESym(r.Sym)
defgotype(ctxt, ctxt.Syms.Lookup("type."+n, 0))
}
}
}
func writelines(ctxt *Link, unit *compilationUnit, ls *sym.Symbol) {
var dwarfctxt dwarf.Context = dwctxt{ctxt}
is_stmt := uint8(1) // initially = recommended default_is_stmt = 1, tracks is_stmt toggles.
unitstart := int64(-1)
headerstart := int64(-1)
headerend := int64(-1)
newattr(unit.dwinfo, dwarf.DW_AT_stmt_list, dwarf.DW_CLS_PTR, ls.Size, ls)
// Write .debug_line Line Number Program Header (sec 6.2.4)
// Fields marked with (*) must be changed for 64-bit dwarf
unitLengthOffset := ls.Size
createUnitLength(ctxt, ls, 0) // unit_length (*), filled in at end
unitstart = ls.Size
ls.AddUint16(ctxt.Arch, 2) // dwarf version (appendix F) -- version 3 is incompatible w/ XCode 9.0's dsymutil, latest supported on OSX 10.12 as of 2018-05
headerLengthOffset := ls.Size
addDwarfAddrField(ctxt, ls, 0) // header_length (*), filled in at end
headerstart = ls.Size
// cpos == unitstart + 4 + 2 + 4
ls.AddUint8(1) // minimum_instruction_length
ls.AddUint8(is_stmt) // default_is_stmt
ls.AddUint8(LINE_BASE & 0xFF) // line_base
ls.AddUint8(LINE_RANGE) // line_range
ls.AddUint8(OPCODE_BASE) // opcode_base
ls.AddUint8(0) // standard_opcode_lengths[1]
ls.AddUint8(1) // standard_opcode_lengths[2]
ls.AddUint8(1) // standard_opcode_lengths[3]
ls.AddUint8(1) // standard_opcode_lengths[4]
ls.AddUint8(1) // standard_opcode_lengths[5]
ls.AddUint8(0) // standard_opcode_lengths[6]
ls.AddUint8(0) // standard_opcode_lengths[7]
ls.AddUint8(0) // standard_opcode_lengths[8]
ls.AddUint8(1) // standard_opcode_lengths[9]
ls.AddUint8(0) // standard_opcode_lengths[10]
ls.AddUint8(0) // include_directories (empty)
// Create the file table. fileNums maps from global file
// indexes (created by numberfile) to CU-local indexes.
fileNums := make(map[int]int)
for _, s := range unit.lib.Textp { // textp has been dead-code-eliminated already.
dsym := dwarfFuncSym(ctxt, s, dwarf.InfoPrefix, true)
for _, f := range s.FuncInfo.File {
if _, ok := fileNums[int(f.Value)]; ok {
continue
}
// File indexes are 1-based.
fileNums[int(f.Value)] = len(fileNums) + 1
Addstring(ls, f.Name)
ls.AddUint8(0)
ls.AddUint8(0)
ls.AddUint8(0)
}
for ri := 0; ri < len(dsym.R); ri++ {
r := &dsym.R[ri]
if r.Type != objabi.R_DWARFFILEREF {
continue
}
// A file that is only mentioned in an inlined subroutine will appear
// as a R_DWARFFILEREF but not in s.FuncInfo.File
if _, ok := fileNums[int(r.Sym.Value)]; ok {
continue
}
fileNums[int(r.Sym.Value)] = len(fileNums) + 1
Addstring(ls, r.Sym.Name)
ls.AddUint8(0)
ls.AddUint8(0)
ls.AddUint8(0)
}
}
// 4 zeros: the string termination + 3 fields.
ls.AddUint8(0)
// terminate file_names.
headerend = ls.Size
ls.AddUint8(0) // start extended opcode
dwarf.Uleb128put(dwarfctxt, ls, 1+int64(ctxt.Arch.PtrSize))
ls.AddUint8(dwarf.DW_LNE_set_address)
s := unit.lib.Textp[0]
pc := s.Value
line := 1
file := 1
ls.AddAddr(ctxt.Arch, s)
pcfile := newPCIter(ctxt)
pcline := newPCIter(ctxt)
pcstmt := newPCIter(ctxt)
for i, s := range unit.lib.Textp {
finddebugruntimepath(s)
pcfile.init(s.FuncInfo.Pcfile.P)
pcline.init(s.FuncInfo.Pcline.P)
isStmtSym := dwarfFuncSym(ctxt, s, dwarf.IsStmtPrefix, false)
if isStmtSym != nil && len(isStmtSym.P) > 0 {
pcstmt.init(isStmtSym.P)
} else {
// Assembly files lack a pcstmt section, we assume that every instruction
// is a valid statement.
pcstmt.done = true
pcstmt.value = 1
}
var thispc uint32
// TODO this loop looks like it could exit with work remaining.
for !pcfile.done && !pcline.done {
// Only changed if it advanced
if int32(file) != pcfile.value {
ls.AddUint8(dwarf.DW_LNS_set_file)
idx, ok := fileNums[int(pcfile.value)]
if !ok {
Exitf("pcln table file missing from DWARF line table")
}
dwarf.Uleb128put(dwarfctxt, ls, int64(idx))
file = int(pcfile.value)
}
// Only changed if it advanced
if is_stmt != uint8(pcstmt.value) {
new_stmt := uint8(pcstmt.value)
switch new_stmt &^ 1 {
case obj.PrologueEnd:
ls.AddUint8(uint8(dwarf.DW_LNS_set_prologue_end))
case obj.EpilogueBegin:
// TODO if there is a use for this, add it.
// Don't forget to increase OPCODE_BASE by 1 and add entry for standard_opcode_lengths[11]
}
new_stmt &= 1
if is_stmt != new_stmt {
is_stmt = new_stmt
ls.AddUint8(uint8(dwarf.DW_LNS_negate_stmt))
}
}
// putpcldelta makes a row in the DWARF matrix, always, even if line is unchanged.
putpclcdelta(ctxt, dwarfctxt, ls, uint64(s.Value+int64(thispc)-pc), int64(pcline.value)-int64(line))
pc = s.Value + int64(thispc)
line = int(pcline.value)
// Take the minimum step forward for the three iterators
thispc = pcfile.nextpc
if pcline.nextpc < thispc {
thispc = pcline.nextpc
}
if !pcstmt.done && pcstmt.nextpc < thispc {
thispc = pcstmt.nextpc
}
if pcfile.nextpc == thispc {
pcfile.next()
}
if !pcstmt.done && pcstmt.nextpc == thispc {
pcstmt.next()
}
if pcline.nextpc == thispc {
pcline.next()
}
}
if is_stmt == 0 && i < len(unit.lib.Textp)-1 {
// If there is more than one function, ensure default value is established.
is_stmt = 1
ls.AddUint8(uint8(dwarf.DW_LNS_negate_stmt))
}
}
ls.AddUint8(0) // start extended opcode
dwarf.Uleb128put(dwarfctxt, ls, 1)
ls.AddUint8(dwarf.DW_LNE_end_sequence)
if ctxt.HeadType == objabi.Haix {
saveDwsectCUSize(".debug_line", unit.lib.String(), uint64(ls.Size-unitLengthOffset))
}
if isDwarf64(ctxt) {
ls.SetUint(ctxt.Arch, unitLengthOffset+4, uint64(ls.Size-unitstart)) // +4 because of 0xFFFFFFFF
ls.SetUint(ctxt.Arch, headerLengthOffset, uint64(headerend-headerstart))
} else {
ls.SetUint32(ctxt.Arch, unitLengthOffset, uint32(ls.Size-unitstart))
ls.SetUint32(ctxt.Arch, headerLengthOffset, uint32(headerend-headerstart))
}
// Apply any R_DWARFFILEREF relocations, since we now know the
// line table file indices for this compilation unit. Note that
// this loop visits only subprogram DIEs: if the compiler is
// changed to generate DW_AT_decl_file attributes for other
// DIE flavors (ex: variables) then those DIEs would need to
// be included below.
missing := make(map[int]interface{})
for _, f := range unit.funcDIEs {
for ri := range f.R {
r := &f.R[ri]
if r.Type != objabi.R_DWARFFILEREF {
continue
}
// Mark relocation as applied (signal to relocsym)
r.Done = true
idx, ok := fileNums[int(r.Sym.Value)]
if ok {
if int(int32(idx)) != idx {
Errorf(f, "bad R_DWARFFILEREF relocation: file index overflow")
}
if r.Siz != 4 {
Errorf(f, "bad R_DWARFFILEREF relocation: has size %d, expected 4", r.Siz)
}
if r.Off < 0 || r.Off+4 > int32(len(f.P)) {
Errorf(f, "bad R_DWARFFILEREF relocation offset %d + 4 would write past length %d", r.Off, len(s.P))
continue
}
ctxt.Arch.ByteOrder.PutUint32(f.P[r.Off:r.Off+4], uint32(idx))
} else {
_, found := missing[int(r.Sym.Value)]
if !found {
Errorf(f, "R_DWARFFILEREF relocation file missing: %v idx %d", r.Sym, r.Sym.Value)
missing[int(r.Sym.Value)] = nil
}
}
}
}
}
// writepcranges generates the DW_AT_ranges table for compilation unit cu.
func writepcranges(ctxt *Link, unit *compilationUnit, base *sym.Symbol, pcs []dwarf.Range, ranges *sym.Symbol) {
var dwarfctxt dwarf.Context = dwctxt{ctxt}
unitLengthOffset := ranges.Size
// Create PC ranges for this CU.
newattr(unit.dwinfo, dwarf.DW_AT_ranges, dwarf.DW_CLS_PTR, ranges.Size, ranges)
newattr(unit.dwinfo, dwarf.DW_AT_low_pc, dwarf.DW_CLS_ADDRESS, base.Value, base)
dwarf.PutRanges(dwarfctxt, ranges, nil, pcs)
if ctxt.HeadType == objabi.Haix {
addDwsectCUSize(".debug_ranges", unit.lib.String(), uint64(ranges.Size-unitLengthOffset))
}
}
/*
* Emit .debug_frame
*/
const (
dataAlignmentFactor = -4
)
// appendPCDeltaCFA appends per-PC CFA deltas to b and returns the final slice.
func appendPCDeltaCFA(arch *sys.Arch, b []byte, deltapc, cfa int64) []byte {
b = append(b, dwarf.DW_CFA_def_cfa_offset_sf)
b = dwarf.AppendSleb128(b, cfa/dataAlignmentFactor)
switch {
case deltapc < 0x40:
b = append(b, uint8(dwarf.DW_CFA_advance_loc+deltapc))
case deltapc < 0x100:
b = append(b, dwarf.DW_CFA_advance_loc1)
b = append(b, uint8(deltapc))
case deltapc < 0x10000:
b = append(b, dwarf.DW_CFA_advance_loc2, 0, 0)
arch.ByteOrder.PutUint16(b[len(b)-2:], uint16(deltapc))
default:
b = append(b, dwarf.DW_CFA_advance_loc4, 0, 0, 0, 0)
arch.ByteOrder.PutUint32(b[len(b)-4:], uint32(deltapc))
}
return b
}
func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol {
var dwarfctxt dwarf.Context = dwctxt{ctxt}
fs := ctxt.Syms.Lookup(".debug_frame", 0)
fs.Type = sym.SDWARFSECT
syms = append(syms, fs)
// Length field is 4 bytes on Dwarf32 and 12 bytes on Dwarf64
lengthFieldSize := int64(4)
if isDwarf64(ctxt) {
lengthFieldSize += 8
}
// Emit the CIE, Section 6.4.1
cieReserve := uint32(16)
if haslinkregister(ctxt) {
cieReserve = 32
}
if isDwarf64(ctxt) {
cieReserve += 4 // 4 bytes added for cid
}
createUnitLength(ctxt, fs, uint64(cieReserve)) // initial length, must be multiple of thearch.ptrsize
addDwarfAddrField(ctxt, fs, ^uint64(0)) // cid
fs.AddUint8(3) // dwarf version (appendix F)
fs.AddUint8(0) // augmentation ""
dwarf.Uleb128put(dwarfctxt, fs, 1) // code_alignment_factor
dwarf.Sleb128put(dwarfctxt, fs, dataAlignmentFactor) // all CFI offset calculations include multiplication with this factor
dwarf.Uleb128put(dwarfctxt, fs, int64(thearch.Dwarfreglr)) // return_address_register
fs.AddUint8(dwarf.DW_CFA_def_cfa) // Set the current frame address..
dwarf.Uleb128put(dwarfctxt, fs, int64(thearch.Dwarfregsp)) // ...to use the value in the platform's SP register (defined in l.go)...
if haslinkregister(ctxt) {
dwarf.Uleb128put(dwarfctxt, fs, int64(0)) // ...plus a 0 offset.
fs.AddUint8(dwarf.DW_CFA_same_value) // The platform's link register is unchanged during the prologue.
dwarf.Uleb128put(dwarfctxt, fs, int64(thearch.Dwarfreglr))
fs.AddUint8(dwarf.DW_CFA_val_offset) // The previous value...
dwarf.Uleb128put(dwarfctxt, fs, int64(thearch.Dwarfregsp)) // ...of the platform's SP register...
dwarf.Uleb128put(dwarfctxt, fs, int64(0)) // ...is CFA+0.
} else {
dwarf.Uleb128put(dwarfctxt, fs, int64(ctxt.Arch.PtrSize)) // ...plus the word size (because the call instruction implicitly adds one word to the frame).
fs.AddUint8(dwarf.DW_CFA_offset_extended) // The previous value...
dwarf.Uleb128put(dwarfctxt, fs, int64(thearch.Dwarfreglr)) // ...of the return address...
dwarf.Uleb128put(dwarfctxt, fs, int64(-ctxt.Arch.PtrSize)/dataAlignmentFactor) // ...is saved at [CFA - (PtrSize/4)].
}
pad := int64(cieReserve) + lengthFieldSize - fs.Size
if pad < 0 {
Exitf("dwarf: cieReserve too small by %d bytes.", -pad)
}
fs.AddBytes(zeros[:pad])
var deltaBuf []byte
pcsp := newPCIter(ctxt)
for _, s := range ctxt.Textp {
if s.FuncInfo == nil {
continue
}
// Emit a FDE, Section 6.4.1.
// First build the section contents into a byte buffer.
deltaBuf = deltaBuf[:0]
if haslinkregister(ctxt) && s.Attr.TopFrame() {
// Mark the link register as having an undefined value.
// This stops call stack unwinders progressing any further.
// TODO: similar mark on non-LR architectures.
deltaBuf = append(deltaBuf, dwarf.DW_CFA_undefined)
deltaBuf = dwarf.AppendUleb128(deltaBuf, uint64(thearch.Dwarfreglr))
}
for pcsp.init(s.FuncInfo.Pcsp.P); !pcsp.done; pcsp.next() {
nextpc := pcsp.nextpc
// pciterinit goes up to the end of the function,
// but DWARF expects us to stop just before the end.
if int64(nextpc) == s.Size {
nextpc--
if nextpc < pcsp.pc {
continue
}
}
spdelta := int64(pcsp.value)
if !haslinkregister(ctxt) {
// Return address has been pushed onto stack.
spdelta += int64(ctxt.Arch.PtrSize)
}
if haslinkregister(ctxt) && !s.Attr.TopFrame() {
// TODO(bryanpkc): This is imprecise. In general, the instruction
// that stores the return address to the stack frame is not the
// same one that allocates the frame.
if pcsp.value > 0 {
// The return address is preserved at (CFA-frame_size)
// after a stack frame has been allocated.
deltaBuf = append(deltaBuf, dwarf.DW_CFA_offset_extended_sf)
deltaBuf = dwarf.AppendUleb128(deltaBuf, uint64(thearch.Dwarfreglr))
deltaBuf = dwarf.AppendSleb128(deltaBuf, -spdelta/dataAlignmentFactor)
} else {
// The return address is restored into the link register
// when a stack frame has been de-allocated.
deltaBuf = append(deltaBuf, dwarf.DW_CFA_same_value)
deltaBuf = dwarf.AppendUleb128(deltaBuf, uint64(thearch.Dwarfreglr))
}
}
deltaBuf = appendPCDeltaCFA(ctxt.Arch, deltaBuf, int64(nextpc)-int64(pcsp.pc), spdelta)
}
pad := int(Rnd(int64(len(deltaBuf)), int64(ctxt.Arch.PtrSize))) - len(deltaBuf)
deltaBuf = append(deltaBuf, zeros[:pad]...)
// Emit the FDE header, Section 6.4.1.
// 4 bytes: length, must be multiple of thearch.ptrsize
// 4/8 bytes: Pointer to the CIE above, at offset 0
// ptrsize: initial location
// ptrsize: address range
fdeLength := uint64(4 + 2*ctxt.Arch.PtrSize + len(deltaBuf))
if isDwarf64(ctxt) {
fdeLength += 4 // 4 bytes added for CIE pointer
}
createUnitLength(ctxt, fs, fdeLength)
if ctxt.LinkMode == LinkExternal {
addDwarfAddrRef(ctxt, fs, fs)
} else {
addDwarfAddrField(ctxt, fs, 0) // CIE offset
}
fs.AddAddr(ctxt.Arch, s)
fs.AddUintXX(ctxt.Arch, uint64(s.Size), ctxt.Arch.PtrSize) // address range
fs.AddBytes(deltaBuf)
if ctxt.HeadType == objabi.Haix {
addDwsectCUSize(".debug_frame", s.File, fdeLength+uint64(lengthFieldSize))
}
}
return syms
}
/*
* Walk DWarfDebugInfoEntries, and emit .debug_info
*/
const (
COMPUNITHEADERSIZE = 4 + 2 + 4 + 1
)
func writeinfo(ctxt *Link, syms []*sym.Symbol, units []*compilationUnit, abbrevsym *sym.Symbol, pubNames, pubTypes *pubWriter) []*sym.Symbol {
infosec := ctxt.Syms.Lookup(".debug_info", 0)
infosec.Type = sym.SDWARFINFO
infosec.Attr |= sym.AttrReachable
syms = append(syms, infosec)
var dwarfctxt dwarf.Context = dwctxt{ctxt}
for _, u := range units {
compunit := u.dwinfo
s := dtolsym(compunit.Sym)
if len(u.lib.Textp) == 0 && u.dwinfo.Child == nil {
continue
}
pubNames.beginCompUnit(compunit)
pubTypes.beginCompUnit(compunit)
// Write .debug_info Compilation Unit Header (sec 7.5.1)
// Fields marked with (*) must be changed for 64-bit dwarf
// This must match COMPUNITHEADERSIZE above.
createUnitLength(ctxt, s, 0) // unit_length (*), will be filled in later.
s.AddUint16(ctxt.Arch, 4) // dwarf version (appendix F)
// debug_abbrev_offset (*)
addDwarfAddrRef(ctxt, s, abbrevsym)
s.AddUint8(uint8(ctxt.Arch.PtrSize)) // address_size
dwarf.Uleb128put(dwarfctxt, s, int64(compunit.Abbrev))
dwarf.PutAttrs(dwarfctxt, s, compunit.Abbrev, compunit.Attr)
cu := []*sym.Symbol{s}
cu = append(cu, u.absFnDIEs...)
cu = append(cu, u.funcDIEs...)
if u.consts != nil {
cu = append(cu, u.consts)
}
var cusize int64
for _, child := range cu {
cusize += child.Size
}
for die := compunit.Child; die != nil; die = die.Link {
l := len(cu)
lastSymSz := cu[l-1].Size
cu = putdie(ctxt, dwarfctxt, cu, die)
if ispubname(die) {
pubNames.add(die, cusize)
}
if ispubtype(die) {
pubTypes.add(die, cusize)
}
if lastSymSz != cu[l-1].Size {
// putdie will sometimes append directly to the last symbol of the list
cusize = cusize - lastSymSz + cu[l-1].Size
}
for _, child := range cu[l:] {
cusize += child.Size
}
}
cu[len(cu)-1].AddUint8(0) // closes compilation unit DIE
cusize++
// Save size for AIX symbol table.
if ctxt.HeadType == objabi.Haix {
saveDwsectCUSize(".debug_info", getPkgFromCUSym(s), uint64(cusize))
}
if isDwarf64(ctxt) {
cusize -= 12 // exclude the length field.
s.SetUint(ctxt.Arch, 4, uint64(cusize)) // 4 because of 0XFFFFFFFF
} else {
cusize -= 4 // exclude the length field.
s.SetUint32(ctxt.Arch, 0, uint32(cusize))
}
pubNames.endCompUnit(compunit, uint32(cusize)+4)
pubTypes.endCompUnit(compunit, uint32(cusize)+4)
syms = append(syms, cu...)
}
return syms
}
/*
* Emit .debug_pubnames/_types. _info must have been written before,
* because we need die->offs and infoo/infosize;
*/
func ispubname(die *dwarf.DWDie) bool {
switch die.Abbrev {
case dwarf.DW_ABRV_FUNCTION, dwarf.DW_ABRV_VARIABLE:
a := getattr(die, dwarf.DW_AT_external)
return a != nil && a.Value != 0
}
return false
}
func ispubtype(die *dwarf.DWDie) bool {
return die.Abbrev >= dwarf.DW_ABRV_NULLTYPE
}
type pubWriter struct {
ctxt *Link
s *sym.Symbol
sname string
sectionstart int64
culengthOff int64
}
func newPubWriter(ctxt *Link, sname string) *pubWriter {
s := ctxt.Syms.Lookup(sname, 0)
s.Type = sym.SDWARFSECT
return &pubWriter{ctxt: ctxt, s: s, sname: sname}
}
func (pw *pubWriter) beginCompUnit(compunit *dwarf.DWDie) {
pw.sectionstart = pw.s.Size
// Write .debug_pubnames/types Header (sec 6.1.1)
createUnitLength(pw.ctxt, pw.s, 0) // unit_length (*), will be filled in later.
pw.s.AddUint16(pw.ctxt.Arch, 2) // dwarf version (appendix F)
addDwarfAddrRef(pw.ctxt, pw.s, dtolsym(compunit.Sym)) // debug_info_offset (of the Comp unit Header)
pw.culengthOff = pw.s.Size
addDwarfAddrField(pw.ctxt, pw.s, uint64(0)) // debug_info_length, will be filled in later.
}
func (pw *pubWriter) add(die *dwarf.DWDie, offset int64) {
dwa := getattr(die, dwarf.DW_AT_name)
name := dwa.Data.(string)
if die.Sym == nil {
fmt.Println("Missing sym for ", name)
}
addDwarfAddrField(pw.ctxt, pw.s, uint64(offset))
Addstring(pw.s, name)
}
func (pw *pubWriter) endCompUnit(compunit *dwarf.DWDie, culength uint32) {
addDwarfAddrField(pw.ctxt, pw.s, 0) // Null offset
// On AIX, save the current size of this compilation unit.
if pw.ctxt.HeadType == objabi.Haix {
saveDwsectCUSize(pw.sname, getPkgFromCUSym(dtolsym(compunit.Sym)), uint64(pw.s.Size-pw.sectionstart))
}
if isDwarf64(pw.ctxt) {
pw.s.SetUint(pw.ctxt.Arch, pw.sectionstart+4, uint64(pw.s.Size-pw.sectionstart)-12) // exclude the length field.
pw.s.SetUint(pw.ctxt.Arch, pw.culengthOff, uint64(culength))
} else {
pw.s.SetUint32(pw.ctxt.Arch, pw.sectionstart, uint32(pw.s.Size-pw.sectionstart)-4) // exclude the length field.
pw.s.SetUint32(pw.ctxt.Arch, pw.culengthOff, culength)
}
}
func writegdbscript(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol {
// TODO (aix): make it available
if ctxt.HeadType == objabi.Haix {
return syms
}
if ctxt.LinkMode == LinkExternal && ctxt.HeadType == objabi.Hwindows && ctxt.BuildMode == BuildModeCArchive {
// gcc on Windows places .debug_gdb_scripts in the wrong location, which
// causes the program not to run. See https://golang.org/issue/20183
// Non c-archives can avoid this issue via a linker script
// (see fix near writeGDBLinkerScript).
// c-archive users would need to specify the linker script manually.
// For UX it's better not to deal with this.
return syms
}
if gdbscript != "" {
s := ctxt.Syms.Lookup(".debug_gdb_scripts", 0)
s.Type = sym.SDWARFSECT
syms = append(syms, s)
s.AddUint8(1) // magic 1 byte?
Addstring(s, gdbscript)
}
return syms
}
var prototypedies map[string]*dwarf.DWDie
func dwarfEnabled(ctxt *Link) bool {
if *FlagW { // disable dwarf
return false
}
if *FlagS && ctxt.HeadType != objabi.Hdarwin {
return false
}
if ctxt.HeadType == objabi.Hplan9 || ctxt.HeadType == objabi.Hjs {
return false
}
if ctxt.LinkMode == LinkExternal {
switch {
case ctxt.IsELF:
case ctxt.HeadType == objabi.Hdarwin:
case ctxt.HeadType == objabi.Hwindows:
case ctxt.HeadType == objabi.Haix:
res, err := dwarf.IsDWARFEnabledOnAIXLd(ctxt.extld())
if err != nil {
Exitf("%v", err)
}
return res
default:
return false
}
}
return true
}
// dwarfGenerateDebugInfo generated debug info entries for all types,
// variables and functions in the program.
// Along with dwarfGenerateDebugSyms they are the two main entry points into
// dwarf generation: dwarfGenerateDebugInfo does all the work that should be
// done before symbol names are mangled while dwarfgeneratedebugsyms does
// all the work that can only be done after addresses have been assigned to
// text symbols.
func dwarfGenerateDebugInfo(ctxt *Link) {
if !dwarfEnabled(ctxt) {
return
}
if ctxt.HeadType == objabi.Haix {
// Initial map used to store package size for each DWARF section.
dwsectCUSize = make(map[string]uint64)
}
ctxt.compUnitByPackage = make(map[*sym.Library]*compilationUnit)
// Forctxt.Diagnostic messages.
newattr(&dwtypes, dwarf.DW_AT_name, dwarf.DW_CLS_STRING, int64(len("dwtypes")), "dwtypes")
// Some types that must exist to define other ones.
newdie(ctxt, &dwtypes, dwarf.DW_ABRV_NULLTYPE, "<unspecified>", 0)
newdie(ctxt, &dwtypes, dwarf.DW_ABRV_NULLTYPE, "void", 0)
newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BARE_PTRTYPE, "unsafe.Pointer", 0)
die := newdie(ctxt, &dwtypes, dwarf.DW_ABRV_BASETYPE, "uintptr", 0) // needed for array size
newattr(die, dwarf.DW_AT_encoding, dwarf.DW_CLS_CONSTANT, dwarf.DW_ATE_unsigned, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, int64(ctxt.Arch.PtrSize), 0)
newattr(die, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, objabi.KindUintptr, 0)
newattr(die, dwarf.DW_AT_go_runtime_type, dwarf.DW_CLS_ADDRESS, 0, lookupOrDiag(ctxt, "type.uintptr"))
// Prototypes needed for type synthesis.
prototypedies = map[string]*dwarf.DWDie{
"type.runtime.stringStructDWARF": nil,
"type.runtime.slice": nil,
"type.runtime.hmap": nil,
"type.runtime.bmap": nil,
"type.runtime.sudog": nil,
"type.runtime.waitq": nil,
"type.runtime.hchan": nil,
}
// Needed by the prettyprinter code for interface inspection.
for _, typ := range []string{
"type.runtime._type",
"type.runtime.arraytype",
"type.runtime.chantype",
"type.runtime.functype",
"type.runtime.maptype",
"type.runtime.ptrtype",
"type.runtime.slicetype",
"type.runtime.structtype",
"type.runtime.interfacetype",
"type.runtime.itab",
"type.runtime.imethod"} {
defgotype(ctxt, lookupOrDiag(ctxt, typ))
}
// fake root DIE for compile unit DIEs
var dwroot dwarf.DWDie
flagVariants := make(map[string]bool)
for _, lib := range ctxt.Library {
unit := &compilationUnit{lib: lib}
if s := ctxt.Syms.ROLookup(dwarf.ConstInfoPrefix+lib.Pkg, 0); s != nil {
importInfoSymbol(ctxt, s)
unit.consts = s
}
ctxt.compUnits = append(ctxt.compUnits, unit)
ctxt.compUnitByPackage[lib] = unit
unit.dwinfo = newdie(ctxt, &dwroot, dwarf.DW_ABRV_COMPUNIT, unit.lib.Pkg, 0)
newattr(unit.dwinfo, dwarf.DW_AT_language, dwarf.DW_CLS_CONSTANT, int64(dwarf.DW_LANG_Go), 0)
// OS X linker requires compilation dir or absolute path in comp unit name to output debug info.
compDir := getCompilationDir()
// TODO: Make this be the actual compilation directory, not
// the linker directory. If we move CU construction into the
// compiler, this should happen naturally.
newattr(unit.dwinfo, dwarf.DW_AT_comp_dir, dwarf.DW_CLS_STRING, int64(len(compDir)), compDir)
producerExtra := ctxt.Syms.Lookup(dwarf.CUInfoPrefix+"producer."+unit.lib.Pkg, 0)
producer := "Go cmd/compile " + objabi.Version
if len(producerExtra.P) > 0 {
// We put a semicolon before the flags to clearly
// separate them from the version, which can be long
// and have lots of weird things in it in development
// versions. We promise not to put a semicolon in the
// version, so it should be safe for readers to scan
// forward to the semicolon.
producer += "; " + string(producerExtra.P)
flagVariants[string(producerExtra.P)] = true
} else {
flagVariants[""] = true
}
newattr(unit.dwinfo, dwarf.DW_AT_producer, dwarf.DW_CLS_STRING, int64(len(producer)), producer)
var pkgname string
if s := ctxt.Syms.ROLookup(dwarf.CUInfoPrefix+"packagename."+unit.lib.Pkg, 0); s != nil {
pkgname = string(s.P)
}
newattr(unit.dwinfo, dwarf.DW_AT_go_package_name, dwarf.DW_CLS_STRING, int64(len(pkgname)), pkgname)
if len(lib.Textp) == 0 {
unit.dwinfo.Abbrev = dwarf.DW_ABRV_COMPUNIT_TEXTLESS
}
// Scan all functions in this compilation unit, create DIEs for all
// referenced types, create the file table for debug_line, find all
// referenced abstract functions.
// Collect all debug_range symbols in unit.rangeSyms
for _, s := range lib.Textp { // textp has been dead-code-eliminated already.
dsym := dwarfFuncSym(ctxt, s, dwarf.InfoPrefix, false)
dsym.Attr |= sym.AttrNotInSymbolTable | sym.AttrReachable
dsym.Type = sym.SDWARFINFO
unit.funcDIEs = append(unit.funcDIEs, dsym)
rangeSym := dwarfFuncSym(ctxt, s, dwarf.RangePrefix, false)
if rangeSym != nil && rangeSym.Size > 0 {
rangeSym.Attr |= sym.AttrReachable | sym.AttrNotInSymbolTable
rangeSym.Type = sym.SDWARFRANGE
// LLVM doesn't support base address entries. Strip them out so LLDB and dsymutil don't get confused.
if ctxt.HeadType == objabi.Hdarwin {
removeDwarfAddrListBaseAddress(ctxt, dsym, rangeSym, false)
}
if ctxt.HeadType == objabi.Haix {
addDwsectCUSize(".debug_ranges", unit.lib.String(), uint64(rangeSym.Size))
}
unit.rangeSyms = append(unit.rangeSyms, rangeSym)
}
for ri := 0; ri < len(dsym.R); ri++ {
r := &dsym.R[ri]
if r.Type == objabi.R_DWARFSECREF {
rsym := r.Sym
if strings.HasPrefix(rsym.Name, dwarf.InfoPrefix) && strings.HasSuffix(rsym.Name, dwarf.AbstractFuncSuffix) && !rsym.Attr.OnList() {
// abstract function
rsym.Attr |= sym.AttrOnList
unit.absFnDIEs = append(unit.absFnDIEs, rsym)
importInfoSymbol(ctxt, rsym)
} else if rsym.Size == 0 {
// a type we do not have a DIE for
n := nameFromDIESym(rsym)
defgotype(ctxt, ctxt.Syms.Lookup("type."+n, 0))
}
}
}
}
}
// Fix for 31034: if the objects feeding into this link were compiled
// with different sets of flags, then don't issue an error if
// the -strictdups checks fail.
if checkStrictDups > 1 && len(flagVariants) > 1 {
checkStrictDups = 1
}
// Create DIEs for global variables and the types they use.
genasmsym(ctxt, defdwsymb)
synthesizestringtypes(ctxt, dwtypes.Child)
synthesizeslicetypes(ctxt, dwtypes.Child)
synthesizemaptypes(ctxt, dwtypes.Child)
synthesizechantypes(ctxt, dwtypes.Child)
}
// dwarfGenerateDebugSyms constructs debug_line, debug_frame, debug_loc,
// debug_pubnames and debug_pubtypes. It also writes out the debug_info
// section using symbols generated in dwarfGenerateDebugInfo.
func dwarfGenerateDebugSyms(ctxt *Link) {
if !dwarfEnabled(ctxt) {
return
}
if ctxt.Debugvlog != 0 {
ctxt.Logf("%5.2f dwarf\n", Cputime())
}
abbrev := writeabbrev(ctxt)
syms := []*sym.Symbol{abbrev}
calcCompUnitRanges(ctxt)
sort.Sort(compilationUnitByStartPC(ctxt.compUnits))
// Write per-package line and range tables and start their CU DIEs.
debugLine := ctxt.Syms.Lookup(".debug_line", 0)
debugLine.Type = sym.SDWARFSECT
debugRanges := ctxt.Syms.Lookup(".debug_ranges", 0)
debugRanges.Type = sym.SDWARFRANGE
debugRanges.Attr |= sym.AttrReachable
syms = append(syms, debugLine)
for _, u := range ctxt.compUnits {
reversetree(&u.dwinfo.Child)
if u.dwinfo.Abbrev == dwarf.DW_ABRV_COMPUNIT_TEXTLESS {
continue
}
writelines(ctxt, u, debugLine)
writepcranges(ctxt, u, u.lib.Textp[0], u.pcs, debugRanges)
}
// newdie adds DIEs to the *beginning* of the parent's DIE list.
// Now that we're done creating DIEs, reverse the trees so DIEs
// appear in the order they were created.
reversetree(&dwtypes.Child)
movetomodule(ctxt, &dwtypes)
pubNames := newPubWriter(ctxt, ".debug_pubnames")
pubTypes := newPubWriter(ctxt, ".debug_pubtypes")
// Need to reorder symbols so sym.SDWARFINFO is after all sym.SDWARFSECT
infosyms := writeinfo(ctxt, nil, ctxt.compUnits, abbrev, pubNames, pubTypes)
syms = writeframes(ctxt, syms)
syms = append(syms, pubNames.s, pubTypes.s)
syms = writegdbscript(ctxt, syms)
// Now we're done writing SDWARFSECT symbols, so we can write
// other SDWARF* symbols.
syms = append(syms, infosyms...)
syms = collectlocs(ctxt, syms, ctxt.compUnits)
syms = append(syms, debugRanges)
for _, unit := range ctxt.compUnits {
syms = append(syms, unit.rangeSyms...)
}
dwarfp = syms
}
func collectlocs(ctxt *Link, syms []*sym.Symbol, units []*compilationUnit) []*sym.Symbol {
empty := true
for _, u := range units {
for _, fn := range u.funcDIEs {
for i := range fn.R {
reloc := &fn.R[i] // Copying sym.Reloc has measurable impact on performance
if reloc.Type == objabi.R_DWARFSECREF && strings.HasPrefix(reloc.Sym.Name, dwarf.LocPrefix) {
reloc.Sym.Attr |= sym.AttrReachable | sym.AttrNotInSymbolTable
syms = append(syms, reloc.Sym)
empty = false
// LLVM doesn't support base address entries. Strip them out so LLDB and dsymutil don't get confused.
if ctxt.HeadType == objabi.Hdarwin {
removeDwarfAddrListBaseAddress(ctxt, fn, reloc.Sym, true)
}
// One location list entry per function, but many relocations to it. Don't duplicate.
break
}
}
}
}
// Don't emit .debug_loc if it's empty -- it makes the ARM linker mad.
if !empty {
locsym := ctxt.Syms.Lookup(".debug_loc", 0)
locsym.Type = sym.SDWARFLOC
locsym.Attr |= sym.AttrReachable
syms = append(syms, locsym)
}
return syms
}
// removeDwarfAddrListBaseAddress removes base address selector entries from
// DWARF location lists and range lists.
func removeDwarfAddrListBaseAddress(ctxt *Link, info, list *sym.Symbol, isloclist bool) {
// The list symbol contains multiple lists, but they're all for the
// same function, and it's not empty.
fn := list.R[0].Sym
// Discard the relocations for the base address entries.
list.R = list.R[:0]
// Add relocations for each location entry's start and end addresses,
// so that the base address entries aren't necessary.
// We could remove them entirely, but that's more work for a relatively
// small size win. If dsymutil runs it'll throw them away anyway.
// relocate adds a CU-relative relocation to fn+addr at offset.
relocate := func(addr uint64, offset int) {
list.R = append(list.R, sym.Reloc{
Off: int32(offset),
Siz: uint8(ctxt.Arch.PtrSize),
Type: objabi.R_ADDRCUOFF,
Add: int64(addr),
Sym: fn,
})
}
for i := 0; i < len(list.P); {
first := readPtr(ctxt, list.P[i:])
second := readPtr(ctxt, list.P[i+ctxt.Arch.PtrSize:])
if (first == 0 && second == 0) ||
first == ^uint64(0) ||
(ctxt.Arch.PtrSize == 4 && first == uint64(^uint32(0))) {
// Base address selection entry or end of list. Ignore.
i += ctxt.Arch.PtrSize * 2
continue
}
relocate(first, i)
relocate(second, i+ctxt.Arch.PtrSize)
// Skip past the actual location.
i += ctxt.Arch.PtrSize * 2
if isloclist {
i += 2 + int(ctxt.Arch.ByteOrder.Uint16(list.P[i:]))
}
}
// Rewrite the DIE's relocations to point to the first location entry,
// not the now-useless base address selection entry.
for i := range info.R {
r := &info.R[i]
if r.Sym != list {
continue
}
r.Add += int64(2 * ctxt.Arch.PtrSize)
}
}
// Read a pointer-sized uint from the beginning of buf.
func readPtr(ctxt *Link, buf []byte) uint64 {
switch ctxt.Arch.PtrSize {
case 4:
return uint64(ctxt.Arch.ByteOrder.Uint32(buf))
case 8:
return ctxt.Arch.ByteOrder.Uint64(buf)
default:
panic("unexpected pointer size")
}
}
/*
* Elf.
*/
func dwarfaddshstrings(ctxt *Link, shstrtab *sym.Symbol) {
if *FlagW { // disable dwarf
return
}
secs := []string{"abbrev", "frame", "info", "loc", "line", "pubnames", "pubtypes", "gdb_scripts", "ranges"}
for _, sec := range secs {
Addstring(shstrtab, ".debug_"+sec)
if ctxt.LinkMode == LinkExternal {
Addstring(shstrtab, elfRelType+".debug_"+sec)
} else {
Addstring(shstrtab, ".zdebug_"+sec)
}
}
}
// Add section symbols for DWARF debug info. This is called before
// dwarfaddelfheaders.
func dwarfaddelfsectionsyms(ctxt *Link) {
if *FlagW { // disable dwarf
return
}
if ctxt.LinkMode != LinkExternal {
return
}
s := ctxt.Syms.Lookup(".debug_info", 0)
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_abbrev", 0)
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_line", 0)
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_frame", 0)
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_loc", 0)
if s.Sect != nil {
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
}
s = ctxt.Syms.Lookup(".debug_ranges", 0)
if s.Sect != nil {
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
}
}
// dwarfcompress compresses the DWARF sections. This must happen after
// relocations are applied. After this, dwarfp will contain a
// different (new) set of symbols, and sections may have been replaced.
func dwarfcompress(ctxt *Link) {
supported := ctxt.IsELF || ctxt.HeadType == objabi.Hwindows || ctxt.HeadType == objabi.Hdarwin
if !ctxt.compressDWARF || !supported || ctxt.LinkMode != LinkInternal {
return
}
var start int
var newDwarfp []*sym.Symbol
Segdwarf.Sections = Segdwarf.Sections[:0]
for i, s := range dwarfp {
// Find the boundaries between sections and compress
// the whole section once we've found the last of its
// symbols.
if i+1 >= len(dwarfp) || s.Sect != dwarfp[i+1].Sect {
s1 := compressSyms(ctxt, dwarfp[start:i+1])
if s1 == nil {
// Compression didn't help.
newDwarfp = append(newDwarfp, dwarfp[start:i+1]...)
Segdwarf.Sections = append(Segdwarf.Sections, s.Sect)
} else {
compressedSegName := ".zdebug_" + s.Sect.Name[len(".debug_"):]
sect := addsection(ctxt.Arch, &Segdwarf, compressedSegName, 04)
sect.Length = uint64(len(s1))
newSym := ctxt.Syms.Lookup(compressedSegName, 0)
newSym.P = s1
newSym.Size = int64(len(s1))
newSym.Sect = sect
newDwarfp = append(newDwarfp, newSym)
}
start = i + 1
}
}
dwarfp = newDwarfp
// Re-compute the locations of the compressed DWARF symbols
// and sections, since the layout of these within the file is
// based on Section.Vaddr and Symbol.Value.
pos := Segdwarf.Vaddr
var prevSect *sym.Section
for _, s := range dwarfp {
s.Value = int64(pos)
if s.Sect != prevSect {
s.Sect.Vaddr = uint64(s.Value)
prevSect = s.Sect
}
if s.Sub != nil {
log.Fatalf("%s: unexpected sub-symbols", s)
}
pos += uint64(s.Size)
if ctxt.HeadType == objabi.Hwindows {
pos = uint64(Rnd(int64(pos), PEFILEALIGN))
}
}
Segdwarf.Length = pos - Segdwarf.Vaddr
}
type compilationUnitByStartPC []*compilationUnit
func (v compilationUnitByStartPC) Len() int { return len(v) }
func (v compilationUnitByStartPC) Swap(i, j int) { v[i], v[j] = v[j], v[i] }
func (v compilationUnitByStartPC) Less(i, j int) bool {
switch {
case len(v[i].lib.Textp) == 0 && len(v[j].lib.Textp) == 0:
return v[i].lib.Pkg < v[j].lib.Pkg
case len(v[i].lib.Textp) != 0 && len(v[j].lib.Textp) == 0:
return true
case len(v[i].lib.Textp) == 0 && len(v[j].lib.Textp) != 0:
return false
default:
return v[i].lib.Textp[0].Value < v[j].lib.Textp[0].Value
}
}
// On AIX, the symbol table needs to know where are the compilation units parts
// for a specific package in each .dw section.
// dwsectCUSize map will save the size of a compilation unit for
// the corresponding .dw section.
// This size can later be retrieved with the index "sectionName.pkgName".
var dwsectCUSize map[string]uint64
// getDwsectCUSize retrieves the corresponding package size inside the current section.
func getDwsectCUSize(sname string, pkgname string) uint64 {
return dwsectCUSize[sname+"."+pkgname]
}
func saveDwsectCUSize(sname string, pkgname string, size uint64) {
dwsectCUSize[sname+"."+pkgname] = size
}
func addDwsectCUSize(sname string, pkgname string, size uint64) {
dwsectCUSize[sname+"."+pkgname] += size
}
// getPkgFromCUSym returns the package name for the compilation unit
// represented by s.
// The prefix dwarf.InfoPrefix+".pkg." needs to be removed in order to get
// the package name.
func getPkgFromCUSym(s *sym.Symbol) string {
return strings.TrimPrefix(s.Name, dwarf.InfoPrefix+".pkg.")
}
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