// Copyright 2019 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/src"
"cmd/internal/sys"
"cmd/link/internal/loader"
"cmd/link/internal/sym"
"cmp"
"fmt"
"internal/abi"
"internal/buildcfg"
"log"
"path"
"runtime"
"slices"
"strings"
"sync"
)
// dwctxt is a wrapper intended to satisfy the method set of
// dwarf.Context, so that functions like dwarf.PutAttrs will work with
// DIEs that use loader.Sym as opposed to *sym.Symbol. It is also
// being used as a place to store tables/maps that are useful as part
// of type conversion (this is just a convenience; it would be easy to
// split these things out into another type if need be).
type dwctxt struct {
linkctxt *Link
ldr *loader.Loader
arch *sys.Arch
// This maps type name string (e.g. "uintptr") to loader symbol for
// the DWARF DIE for that type (e.g. "go:info.type.uintptr")
tmap map[string]loader.Sym
// This maps loader symbol for the DWARF DIE symbol generated for
// a type (e.g. "go:info.uintptr") to the type symbol itself
// ("type:uintptr").
// FIXME: try converting this map (and the next one) to a single
// array indexed by loader.Sym -- this may perform better.
rtmap map[loader.Sym]loader.Sym
// This maps Go type symbol (e.g. "type:XXX") to loader symbol for
// the typedef DIE for that type (e.g. "go:info.XXX..def")
tdmap map[loader.Sym]loader.Sym
// Cache these type symbols, so as to avoid repeatedly looking them up
typeRuntimeEface loader.Sym
typeRuntimeIface loader.Sym
uintptrInfoSym loader.Sym
// Used at various points in that parallel portion of DWARF gen to
// protect against conflicting updates to globals (such as "gdbscript")
dwmu *sync.Mutex
}
// dwSym wraps a loader.Sym; this type is meant to obey the interface
// rules for dwarf.Sym from the cmd/internal/dwarf package. DwDie and
// DwAttr objects contain references to symbols via this type.
type dwSym loader.Sym
func (c dwctxt) PtrSize() int {
return c.arch.PtrSize
}
func (c dwctxt) Size(s dwarf.Sym) int64 {
return int64(len(c.ldr.Data(loader.Sym(s.(dwSym)))))
}
func (c dwctxt) AddInt(s dwarf.Sym, size int, i int64) {
ds := loader.Sym(s.(dwSym))
dsu := c.ldr.MakeSymbolUpdater(ds)
dsu.AddUintXX(c.arch, uint64(i), size)
}
func (c dwctxt) AddBytes(s dwarf.Sym, b []byte) {
ds := loader.Sym(s.(dwSym))
dsu := c.ldr.MakeSymbolUpdater(ds)
dsu.AddBytes(b)
}
func (c dwctxt) AddString(s dwarf.Sym, v string) {
ds := loader.Sym(s.(dwSym))
dsu := c.ldr.MakeSymbolUpdater(ds)
dsu.Addstring(v)
}
func (c dwctxt) AddAddress(s dwarf.Sym, data interface{}, value int64) {
ds := loader.Sym(s.(dwSym))
dsu := c.ldr.MakeSymbolUpdater(ds)
if value != 0 {
value -= dsu.Value()
}
tgtds := loader.Sym(data.(dwSym))
dsu.AddAddrPlus(c.arch, tgtds, value)
}
func (c dwctxt) AddCURelativeAddress(s dwarf.Sym, data interface{}, value int64) {
ds := loader.Sym(s.(dwSym))
dsu := c.ldr.MakeSymbolUpdater(ds)
if value != 0 {
value -= dsu.Value()
}
tgtds := loader.Sym(data.(dwSym))
dsu.AddCURelativeAddrPlus(c.arch, tgtds, value)
}
func (c dwctxt) AddSectionOffset(s dwarf.Sym, size int, t interface{}, ofs int64) {
ds := loader.Sym(s.(dwSym))
dsu := c.ldr.MakeSymbolUpdater(ds)
tds := loader.Sym(t.(dwSym))
switch size {
default:
c.linkctxt.Errorf(ds, "invalid size %d in adddwarfref\n", size)
case c.arch.PtrSize, 4:
}
dsu.AddSymRef(c.arch, tds, ofs, objabi.R_ADDROFF, size)
}
func (c dwctxt) AddDWARFAddrSectionOffset(s dwarf.Sym, t interface{}, ofs int64) {
size := 4
if isDwarf64(c.linkctxt) {
size = 8
}
ds := loader.Sym(s.(dwSym))
dsu := c.ldr.MakeSymbolUpdater(ds)
tds := loader.Sym(t.(dwSym))
switch size {
default:
c.linkctxt.Errorf(ds, "invalid size %d in adddwarfref\n", size)
case c.arch.PtrSize, 4:
}
dsu.AddSymRef(c.arch, tds, ofs, objabi.R_DWARFSECREF, size)
}
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) 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
}
// https://sourceware.org/gdb/onlinedocs/gdb/dotdebug_005fgdb_005fscripts-section.html
// Each entry inside .debug_gdb_scripts section begins with a non-null prefix
// byte that specifies the kind of entry. The following entries are supported:
const (
GdbScriptPythonFileId = 1
GdbScriptSchemeFileId = 3
GdbScriptPythonTextId = 4
GdbScriptSchemeTextId = 6
)
var gdbscript string
// dwarfSecInfo holds information about a DWARF output section,
// specifically a section symbol and a list of symbols contained in
// that section. On the syms list, the first symbol will always be the
// section symbol, then any remaining symbols (if any) will be
// sub-symbols in that section. Note that for some sections (eg:
// .debug_abbrev), the section symbol is all there is (all content is
// contained in it). For other sections (eg: .debug_info), the section
// symbol is empty and all the content is in the sub-symbols. Finally
// there are some sections (eg: .debug_ranges) where it is a mix (both
// the section symbol and the sub-symbols have content)
type dwarfSecInfo struct {
syms []loader.Sym
}
// secSym returns the section symbol for the section.
func (dsi *dwarfSecInfo) secSym() loader.Sym {
if len(dsi.syms) == 0 {
return 0
}
return dsi.syms[0]
}
// subSyms returns a list of sub-symbols for the section.
func (dsi *dwarfSecInfo) subSyms() []loader.Sym {
if len(dsi.syms) == 0 {
return []loader.Sym{}
}
return dsi.syms[1:]
}
// dwarfp stores the collected DWARF symbols created during
// dwarf generation.
var dwarfp []dwarfSecInfo
func (d *dwctxt) writeabbrev() dwarfSecInfo {
abrvs := d.ldr.CreateSymForUpdate(".debug_abbrev", 0)
abrvs.SetType(sym.SDWARFSECT)
abrvs.AddBytes(dwarf.GetAbbrev())
return dwarfSecInfo{syms: []loader.Sym{abrvs.Sym()}}
}
var dwtypes dwarf.DWDie
// newattr attaches a new attribute to the specified DIE.
//
// FIXME: at the moment attributes are stored in a linked list in a
// fairly space-inefficient way -- it might be better to instead look
// up all attrs in a single large table, then store indices into the
// table in the DIE. This would allow us to common up storage for
// attributes that are shared by many DIEs (ex: byte size of N).
func newattr(die *dwarf.DWDie, attr uint16, cls int, value int64, data interface{}) {
a := new(dwarf.DWAttr)
a.Link = die.Attr
die.Attr = a
a.Atr = attr
a.Cls = uint8(cls)
a.Value = value
a.Data = data
}
// 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).
// FIXME: it would be more efficient to bulk-allocate DIEs.
func (d *dwctxt) newdie(parent *dwarf.DWDie, abbrev int, name string) *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)
// Sanity check: all DIEs created in the linker should be named.
if name == "" {
panic("nameless DWARF DIE")
}
var st sym.SymKind
switch abbrev {
case dwarf.DW_ABRV_FUNCTYPEPARAM, dwarf.DW_ABRV_FUNCTYPEOUTPARAM, dwarf.DW_ABRV_DOTDOTDOT, dwarf.DW_ABRV_STRUCTFIELD, dwarf.DW_ABRV_ARRAYRANGE:
// There are no relocations against these dies, and their names
// are not unique, so don't create a symbol.
return die
case dwarf.DW_ABRV_COMPUNIT, dwarf.DW_ABRV_COMPUNIT_TEXTLESS:
// Avoid collisions with "real" symbol names.
name = fmt.Sprintf(".pkg.%s.%d", name, len(d.linkctxt.compUnits))
st = sym.SDWARFCUINFO
case dwarf.DW_ABRV_VARIABLE:
st = sym.SDWARFVAR
default:
// Everything else is assigned a type of SDWARFTYPE. that
// this also includes loose ends such as STRUCT_FIELD.
st = sym.SDWARFTYPE
}
ds := d.ldr.LookupOrCreateSym(dwarf.InfoPrefix+name, 0)
dsu := d.ldr.MakeSymbolUpdater(ds)
dsu.SetType(st)
d.ldr.SetAttrNotInSymbolTable(ds, true)
d.ldr.SetAttrReachable(ds, true)
die.Sym = dwSym(ds)
if abbrev >= dwarf.DW_ABRV_NULLTYPE && abbrev <= dwarf.DW_ABRV_TYPEDECL {
d.tmap[name] = ds
}
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 (d *dwctxt) walksymtypedef(symIdx loader.Sym) loader.Sym {
// We're being given the loader symbol for the type DIE, e.g.
// "go:info.type.uintptr". Map that first to the type symbol (e.g.
// "type:uintptr") and then to the typedef DIE for the type.
// FIXME: this seems clunky, maybe there is a better way to do this.
if ts, ok := d.rtmap[symIdx]; ok {
if def, ok := d.tdmap[ts]; ok {
return def
}
d.linkctxt.Errorf(ts, "internal error: no entry for sym %d in tdmap\n", ts)
return 0
}
d.linkctxt.Errorf(symIdx, "internal error: no entry for sym %d in rtmap\n", symIdx)
return 0
}
// 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
}
// find looks up the loader symbol for the DWARF DIE generated for the
// type with the specified name.
func (d *dwctxt) find(name string) loader.Sym {
return d.tmap[name]
}
func (d *dwctxt) mustFind(name string) loader.Sym {
r := d.find(name)
if r == 0 {
Exitf("dwarf find: cannot find %s", name)
}
return r
}
func (d *dwctxt) adddwarfref(sb *loader.SymbolBuilder, t loader.Sym, size int) {
switch size {
default:
d.linkctxt.Errorf(sb.Sym(), "invalid size %d in adddwarfref\n", size)
case d.arch.PtrSize, 4:
}
sb.AddSymRef(d.arch, t, 0, objabi.R_DWARFSECREF, size)
}
func (d *dwctxt) newrefattr(die *dwarf.DWDie, attr uint16, ref loader.Sym) {
if ref == 0 {
return
}
newattr(die, attr, dwarf.DW_CLS_REFERENCE, 0, dwSym(ref))
}
func (d *dwctxt) dtolsym(s dwarf.Sym) loader.Sym {
if s == nil {
return 0
}
dws := loader.Sym(s.(dwSym))
return dws
}
func (d *dwctxt) putdie(syms []loader.Sym, die *dwarf.DWDie) []loader.Sym {
s := d.dtolsym(die.Sym)
if s == 0 {
s = syms[len(syms)-1]
} else {
syms = append(syms, s)
}
sDwsym := dwSym(s)
dwarf.Uleb128put(d, sDwsym, int64(die.Abbrev))
dwarf.PutAttrs(d, sDwsym, die.Abbrev, die.Attr)
if dwarf.HasChildren(die) {
for die := die.Child; die != nil; die = die.Link {
syms = d.putdie(syms, die)
}
dsu := d.ldr.MakeSymbolUpdater(syms[len(syms)-1])
dsu.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)
}
func (d *dwctxt) lookupOrDiag(n string) loader.Sym {
symIdx := d.ldr.Lookup(n, 0)
if symIdx == 0 {
Exitf("dwarf: missing type: %s", n)
}
if len(d.ldr.Data(symIdx)) == 0 {
Exitf("dwarf: missing type (no data): %s", n)
}
return symIdx
}
func (d *dwctxt) dotypedef(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
}
// cmd/compile uses "noalg.struct {...}" as type name when hash and eq algorithm generation of
// this struct type is suppressed.
if strings.HasPrefix(name, "noalg.struct {") {
return nil
}
if strings.HasPrefix(name, "chan ") {
return nil
}
if name[0] == '[' || name[0] == '*' {
return nil
}
if def == nil {
Errorf("dwarf: bad def in dotypedef")
}
// Create a new loader symbol for the typedef. We no longer
// do lookups of typedef symbols by name, so this is going
// to be an anonymous symbol (we want this for perf reasons).
tds := d.ldr.CreateExtSym("", 0)
tdsu := d.ldr.MakeSymbolUpdater(tds)
tdsu.SetType(sym.SDWARFTYPE)
def.Sym = dwSym(tds)
d.ldr.SetAttrNotInSymbolTable(tds, true)
d.ldr.SetAttrReachable(tds, true)
// 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 := d.newdie(parent, dwarf.DW_ABRV_TYPEDECL, name)
d.newrefattr(die, dwarf.DW_AT_type, tds)
return die
}
// Define gotype, for composite ones recurse into constituents.
func (d *dwctxt) defgotype(gotype loader.Sym) loader.Sym {
if gotype == 0 {
return d.mustFind("<unspecified>")
}
// If we already have a tdmap entry for the gotype, return it.
if ds, ok := d.tdmap[gotype]; ok {
return ds
}
sn := d.ldr.SymName(gotype)
if !strings.HasPrefix(sn, "type:") {
d.linkctxt.Errorf(gotype, "dwarf: type name doesn't start with \"type:\"")
return d.mustFind("<unspecified>")
}
name := sn[len("type:"):] // could also decode from Type.string
sdie := d.find(name)
if sdie != 0 {
return sdie
}
gtdwSym := d.newtype(gotype)
d.tdmap[gotype] = loader.Sym(gtdwSym.Sym.(dwSym))
return loader.Sym(gtdwSym.Sym.(dwSym))
}
func (d *dwctxt) newtype(gotype loader.Sym) *dwarf.DWDie {
sn := d.ldr.SymName(gotype)
name := sn[len("type:"):] // could also decode from Type.string
tdata := d.ldr.Data(gotype)
if len(tdata) == 0 {
d.linkctxt.Errorf(gotype, "missing type")
}
kind := decodetypeKind(d.arch, tdata)
bytesize := decodetypeSize(d.arch, tdata)
var die, typedefdie *dwarf.DWDie
switch kind {
case abi.Bool:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_BASETYPE, name)
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 abi.Int,
abi.Int8,
abi.Int16,
abi.Int32,
abi.Int64:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_BASETYPE, name)
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 abi.Uint,
abi.Uint8,
abi.Uint16,
abi.Uint32,
abi.Uint64,
abi.Uintptr:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_BASETYPE, name)
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 abi.Float32,
abi.Float64:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_BASETYPE, name)
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 abi.Complex64,
abi.Complex128:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_BASETYPE, name)
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 abi.Array:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_ARRAYTYPE, name)
typedefdie = d.dotypedef(&dwtypes, name, die)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
s := decodetypeArrayElem(d.linkctxt, d.arch, gotype)
d.newrefattr(die, dwarf.DW_AT_type, d.defgotype(s))
fld := d.newdie(die, dwarf.DW_ABRV_ARRAYRANGE, "range")
// use actual length not upper bound; correct for 0-length arrays.
newattr(fld, dwarf.DW_AT_count, dwarf.DW_CLS_CONSTANT, decodetypeArrayLen(d.ldr, d.arch, gotype), 0)
d.newrefattr(fld, dwarf.DW_AT_type, d.uintptrInfoSym)
case abi.Chan:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_CHANTYPE, name)
s := decodetypeChanElem(d.ldr, d.arch, gotype)
d.newrefattr(die, dwarf.DW_AT_go_elem, d.defgotype(s))
// Save elem type for synthesizechantypes. We could synthesize here
// but that would change the order of DIEs we output.
d.newrefattr(die, dwarf.DW_AT_type, s)
case abi.Func:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_FUNCTYPE, name)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
typedefdie = d.dotypedef(&dwtypes, name, die)
data := d.ldr.Data(gotype)
// FIXME: add caching or reuse reloc slice.
relocs := d.ldr.Relocs(gotype)
nfields := decodetypeFuncInCount(d.arch, data)
for i := 0; i < nfields; i++ {
s := decodetypeFuncInType(d.ldr, d.arch, gotype, &relocs, i)
sn := d.ldr.SymName(s)
fld := d.newdie(die, dwarf.DW_ABRV_FUNCTYPEPARAM, sn[5:])
d.newrefattr(fld, dwarf.DW_AT_type, d.defgotype(s))
}
if decodetypeFuncDotdotdot(d.arch, data) {
d.newdie(die, dwarf.DW_ABRV_DOTDOTDOT, "...")
}
nfields = decodetypeFuncOutCount(d.arch, data)
for i := 0; i < nfields; i++ {
s := decodetypeFuncOutType(d.ldr, d.arch, gotype, &relocs, i)
sn := d.ldr.SymName(s)
fld := d.newdie(die, dwarf.DW_ABRV_FUNCTYPEOUTPARAM, sn[5:])
newattr(fld, dwarf.DW_AT_variable_parameter, dwarf.DW_CLS_FLAG, 1, 0)
d.newrefattr(fld, dwarf.DW_AT_type, d.defgotype(s))
}
case abi.Interface:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_IFACETYPE, name)
typedefdie = d.dotypedef(&dwtypes, name, die)
data := d.ldr.Data(gotype)
nfields := int(decodetypeIfaceMethodCount(d.arch, data))
var s loader.Sym
if nfields == 0 {
s = d.typeRuntimeEface
} else {
s = d.typeRuntimeIface
}
d.newrefattr(die, dwarf.DW_AT_type, d.defgotype(s))
case abi.Map:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_MAPTYPE, name)
s := decodetypeMapKey(d.ldr, d.arch, gotype)
d.newrefattr(die, dwarf.DW_AT_go_key, d.defgotype(s))
s = decodetypeMapValue(d.ldr, d.arch, gotype)
d.newrefattr(die, dwarf.DW_AT_go_elem, d.defgotype(s))
// Save gotype for use in synthesizemaptypes. We could synthesize here,
// but that would change the order of the DIEs.
d.newrefattr(die, dwarf.DW_AT_type, gotype)
case abi.Pointer:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_PTRTYPE, name)
typedefdie = d.dotypedef(&dwtypes, name, die)
s := decodetypePtrElem(d.ldr, d.arch, gotype)
d.newrefattr(die, dwarf.DW_AT_type, d.defgotype(s))
case abi.Slice:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_SLICETYPE, name)
typedefdie = d.dotypedef(&dwtypes, name, die)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
s := decodetypeArrayElem(d.linkctxt, d.arch, gotype)
elem := d.defgotype(s)
d.newrefattr(die, dwarf.DW_AT_go_elem, elem)
case abi.String:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_STRINGTYPE, name)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
case abi.Struct:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_STRUCTTYPE, name)
typedefdie = d.dotypedef(&dwtypes, name, die)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
nfields := decodetypeStructFieldCount(d.ldr, d.arch, gotype)
for i := 0; i < nfields; i++ {
f := decodetypeStructFieldName(d.ldr, d.arch, gotype, i)
s := decodetypeStructFieldType(d.linkctxt, d.arch, gotype, i)
if f == "" {
sn := d.ldr.SymName(s)
f = sn[5:] // skip "type:"
}
fld := d.newdie(die, dwarf.DW_ABRV_STRUCTFIELD, f)
d.newrefattr(fld, dwarf.DW_AT_type, d.defgotype(s))
offset := decodetypeStructFieldOffset(d.ldr, d.arch, gotype, i)
newmemberoffsetattr(fld, int32(offset))
if decodetypeStructFieldEmbedded(d.ldr, d.arch, gotype, i) {
newattr(fld, dwarf.DW_AT_go_embedded_field, dwarf.DW_CLS_FLAG, 1, 0)
}
}
case abi.UnsafePointer:
die = d.newdie(&dwtypes, dwarf.DW_ABRV_BARE_PTRTYPE, name)
default:
d.linkctxt.Errorf(gotype, "dwarf: definition of unknown kind %d", kind)
die = d.newdie(&dwtypes, dwarf.DW_ABRV_TYPEDECL, name)
d.newrefattr(die, dwarf.DW_AT_type, d.mustFind("<unspecified>"))
}
newattr(die, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, int64(kind), 0)
if d.ldr.AttrReachable(gotype) {
newattr(die, dwarf.DW_AT_go_runtime_type, dwarf.DW_CLS_GO_TYPEREF, 0, dwSym(gotype))
}
// Sanity check.
if _, ok := d.rtmap[gotype]; ok {
log.Fatalf("internal error: rtmap entry already installed\n")
}
ds := loader.Sym(die.Sym.(dwSym))
if typedefdie != nil {
ds = loader.Sym(typedefdie.Sym.(dwSym))
}
d.rtmap[ds] = gotype
if _, ok := prototypedies[sn]; ok {
prototypedies[sn] = die
}
if typedefdie != nil {
return typedefdie
}
return die
}
func (d *dwctxt) nameFromDIESym(dwtypeDIESym loader.Sym) string {
sn := d.ldr.SymName(dwtypeDIESym)
return sn[len(dwarf.InfoPrefix):]
}
func (d *dwctxt) defptrto(dwtype loader.Sym) loader.Sym {
// FIXME: it would be nice if the compiler attached an aux symbol
// ref from the element type to the pointer type -- it would be
// more efficient to do it this way as opposed to via name lookups.
ptrname := "*" + d.nameFromDIESym(dwtype)
if die := d.find(ptrname); die != 0 {
return die
}
pdie := d.newdie(&dwtypes, dwarf.DW_ABRV_PTRTYPE, ptrname)
d.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.
gts := d.ldr.Lookup("type:"+ptrname, 0)
if gts != 0 && d.ldr.AttrReachable(gts) {
newattr(pdie, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, int64(abi.Pointer), 0)
newattr(pdie, dwarf.DW_AT_go_runtime_type, dwarf.DW_CLS_GO_TYPEREF, 0, dwSym(gts))
}
if gts != 0 {
ds := loader.Sym(pdie.Sym.(dwSym))
d.rtmap[ds] = gts
d.tdmap[gts] = ds
}
return d.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 (d *dwctxt) 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 := d.newdie(dst, src.Abbrev, getattr(src, dwarf.DW_AT_name).Data.(string))
for a := src.Attr; a != nil; a = a.Link {
newattr(c, a.Atr, int(a.Cls), a.Value, a.Data)
}
d.copychildrenexcept(ctxt, c, src, nil)
}
reverselist(&dst.Child)
}
func (d *dwctxt) copychildren(ctxt *Link, dst *dwarf.DWDie, src *dwarf.DWDie) {
d.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 (d *dwctxt) substitutetype(structdie *dwarf.DWDie, field string, dwtype loader.Sym) {
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 = dwSym(dwtype)
} else {
d.newrefattr(child, dwarf.DW_AT_type, dwtype)
}
}
func (d *dwctxt) findprotodie(ctxt *Link, name string) *dwarf.DWDie {
die, ok := prototypedies[name]
if ok && die == nil {
d.defgotype(d.lookupOrDiag(name))
die = prototypedies[name]
}
if die == nil {
log.Fatalf("internal error: DIE generation failed for %s\n", name)
}
return die
}
func (d *dwctxt) synthesizestringtypes(ctxt *Link, die *dwarf.DWDie) {
prototype := walktypedef(d.findprotodie(ctxt, "type:runtime.stringStructDWARF"))
if prototype == nil {
return
}
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_STRINGTYPE {
continue
}
d.copychildren(ctxt, die, prototype)
}
}
func (d *dwctxt) synthesizeslicetypes(ctxt *Link, die *dwarf.DWDie) {
prototype := walktypedef(d.findprotodie(ctxt, "type:runtime.slice"))
if prototype == nil {
return
}
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_SLICETYPE {
continue
}
d.copychildren(ctxt, die, prototype)
elem := loader.Sym(getattr(die, dwarf.DW_AT_go_elem).Data.(dwSym))
d.substitutetype(die, "array", d.defptrto(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)
}
func (d *dwctxt) mkinternaltype(ctxt *Link, abbrev int, typename, keyname, valname string, f func(*dwarf.DWDie)) loader.Sym {
name := mkinternaltypename(typename, keyname, valname)
symname := dwarf.InfoPrefix + name
s := d.ldr.Lookup(symname, 0)
if s != 0 && d.ldr.SymType(s) == sym.SDWARFTYPE {
return s
}
die := d.newdie(&dwtypes, abbrev, name)
f(die)
return d.dtolsym(die.Sym)
}
func (d *dwctxt) synthesizemaptypes(ctxt *Link, die *dwarf.DWDie) {
if buildcfg.Experiment.SwissMap {
d.synthesizemaptypesSwiss(ctxt, die)
} else {
d.synthesizemaptypesOld(ctxt, die)
}
}
func (d *dwctxt) synthesizemaptypesSwiss(ctxt *Link, die *dwarf.DWDie) {
mapType := walktypedef(d.findprotodie(ctxt, "type:internal/runtime/maps.Map"))
tableType := walktypedef(d.findprotodie(ctxt, "type:internal/runtime/maps.table"))
groupsReferenceType := walktypedef(d.findprotodie(ctxt, "type:internal/runtime/maps.groupsReference"))
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_MAPTYPE {
continue
}
gotype := loader.Sym(getattr(die, dwarf.DW_AT_type).Data.(dwSym))
keyType := decodetypeMapKey(d.ldr, d.arch, gotype)
valType := decodetypeMapValue(d.ldr, d.arch, gotype)
groupType := decodetypeMapSwissGroup(d.ldr, d.arch, gotype)
keyType = d.walksymtypedef(d.defgotype(keyType))
valType = d.walksymtypedef(d.defgotype(valType))
groupType = d.walksymtypedef(d.defgotype(groupType))
keyName := d.nameFromDIESym(keyType)
valName := d.nameFromDIESym(valType)
// Construct groupsReference[K,V]
dwGroupsReference := d.mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "groupReference", keyName, valName, func(dwh *dwarf.DWDie) {
d.copychildren(ctxt, dwh, groupsReferenceType)
// data *group[K,V]
//
// This is actually a pointer to an array
// *[lengthMask+1]group[K,V], but the length is
// variable, so we can't statically record the length.
d.substitutetype(dwh, "data", d.defptrto(groupType))
newattr(dwh, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(groupsReferenceType, dwarf.DW_AT_byte_size).Value, nil)
newattr(dwh, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, int64(abi.Struct), 0)
})
// Construct table[K,V]
dwTable := d.mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "table", keyName, valName, func(dwh *dwarf.DWDie) {
d.copychildren(ctxt, dwh, tableType)
d.substitutetype(dwh, "groups", dwGroupsReference)
newattr(dwh, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(tableType, dwarf.DW_AT_byte_size).Value, nil)
newattr(dwh, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, int64(abi.Struct), 0)
})
// Construct map[K,V]
dwMap := d.mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "map", keyName, valName, func(dwh *dwarf.DWDie) {
d.copychildren(ctxt, dwh, mapType)
// dirPtr is a pointer to a variable-length array of
// *table[K,V], of length dirLen.
//
// Since we can't directly define a variable-length
// array, store this as **table[K,V]. i.e., pointer to
// the first entry in the array.
d.substitutetype(dwh, "dirPtr", d.defptrto(d.defptrto(dwTable)))
newattr(dwh, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(mapType, dwarf.DW_AT_byte_size).Value, nil)
newattr(dwh, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, int64(abi.Struct), 0)
})
// make map type a pointer to map[K,V]
d.newrefattr(die, dwarf.DW_AT_type, d.defptrto(dwMap))
}
}
func (d *dwctxt) synthesizemaptypesOld(ctxt *Link, die *dwarf.DWDie) {
hash := walktypedef(d.findprotodie(ctxt, "type:runtime.hmap"))
bucket := walktypedef(d.findprotodie(ctxt, "type:runtime.bmap"))
if hash == nil {
return
}
for ; die != nil; die = die.Link {
if die.Abbrev != dwarf.DW_ABRV_MAPTYPE {
continue
}
gotype := loader.Sym(getattr(die, dwarf.DW_AT_type).Data.(dwSym))
keytype := decodetypeMapKey(d.ldr, d.arch, gotype)
valtype := decodetypeMapValue(d.ldr, d.arch, gotype)
keydata := d.ldr.Data(keytype)
valdata := d.ldr.Data(valtype)
keysize, valsize := decodetypeSize(d.arch, keydata), decodetypeSize(d.arch, valdata)
keytype, valtype = d.walksymtypedef(d.defgotype(keytype)), d.walksymtypedef(d.defgotype(valtype))
// compute size info like hashmap.c does.
indirectKey, indirectVal := false, false
if keysize > abi.OldMapMaxKeyBytes {
keysize = int64(d.arch.PtrSize)
indirectKey = true
}
if valsize > abi.OldMapMaxElemBytes {
valsize = int64(d.arch.PtrSize)
indirectVal = true
}
// Construct type to represent an array of BucketSize keys
keyname := d.nameFromDIESym(keytype)
dwhks := d.mkinternaltype(ctxt, dwarf.DW_ABRV_ARRAYTYPE, "[]key", keyname, "", func(dwhk *dwarf.DWDie) {
newattr(dwhk, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, abi.OldMapBucketCount*keysize, 0)
t := keytype
if indirectKey {
t = d.defptrto(keytype)
}
d.newrefattr(dwhk, dwarf.DW_AT_type, t)
fld := d.newdie(dwhk, dwarf.DW_ABRV_ARRAYRANGE, "size")
newattr(fld, dwarf.DW_AT_count, dwarf.DW_CLS_CONSTANT, abi.OldMapBucketCount, 0)
d.newrefattr(fld, dwarf.DW_AT_type, d.uintptrInfoSym)
})
// Construct type to represent an array of BucketSize values
valname := d.nameFromDIESym(valtype)
dwhvs := d.mkinternaltype(ctxt, dwarf.DW_ABRV_ARRAYTYPE, "[]val", valname, "", func(dwhv *dwarf.DWDie) {
newattr(dwhv, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, abi.OldMapBucketCount*valsize, 0)
t := valtype
if indirectVal {
t = d.defptrto(valtype)
}
d.newrefattr(dwhv, dwarf.DW_AT_type, t)
fld := d.newdie(dwhv, dwarf.DW_ABRV_ARRAYRANGE, "size")
newattr(fld, dwarf.DW_AT_count, dwarf.DW_CLS_CONSTANT, abi.OldMapBucketCount, 0)
d.newrefattr(fld, dwarf.DW_AT_type, d.uintptrInfoSym)
})
// Construct bucket<K,V>
dwhbs := d.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.
d.copychildrenexcept(ctxt, dwhb, bucket, findchild(bucket, "data"))
fld := d.newdie(dwhb, dwarf.DW_ABRV_STRUCTFIELD, "keys")
d.newrefattr(fld, dwarf.DW_AT_type, dwhks)
newmemberoffsetattr(fld, abi.OldMapBucketCount)
fld = d.newdie(dwhb, dwarf.DW_ABRV_STRUCTFIELD, "values")
d.newrefattr(fld, dwarf.DW_AT_type, dwhvs)
newmemberoffsetattr(fld, abi.OldMapBucketCount+abi.OldMapBucketCount*int32(keysize))
fld = d.newdie(dwhb, dwarf.DW_ABRV_STRUCTFIELD, "overflow")
d.newrefattr(fld, dwarf.DW_AT_type, d.defptrto(d.dtolsym(dwhb.Sym)))
newmemberoffsetattr(fld, abi.OldMapBucketCount+abi.OldMapBucketCount*(int32(keysize)+int32(valsize)))
if d.arch.RegSize > d.arch.PtrSize {
fld = d.newdie(dwhb, dwarf.DW_ABRV_STRUCTFIELD, "pad")
d.newrefattr(fld, dwarf.DW_AT_type, d.uintptrInfoSym)
newmemberoffsetattr(fld, abi.OldMapBucketCount+abi.OldMapBucketCount*(int32(keysize)+int32(valsize))+int32(d.arch.PtrSize))
}
newattr(dwhb, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, abi.OldMapBucketCount+abi.OldMapBucketCount*keysize+abi.OldMapBucketCount*valsize+int64(d.arch.RegSize), 0)
})
// Construct hash<K,V>
dwhs := d.mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "hash", keyname, valname, func(dwh *dwarf.DWDie) {
d.copychildren(ctxt, dwh, hash)
d.substitutetype(dwh, "buckets", d.defptrto(dwhbs))
d.substitutetype(dwh, "oldbuckets", d.defptrto(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>
d.newrefattr(die, dwarf.DW_AT_type, d.defptrto(dwhs))
}
}
func (d *dwctxt) synthesizechantypes(ctxt *Link, die *dwarf.DWDie) {
sudog := walktypedef(d.findprotodie(ctxt, "type:runtime.sudog"))
waitq := walktypedef(d.findprotodie(ctxt, "type:runtime.waitq"))
hchan := walktypedef(d.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 := loader.Sym(getattr(die, dwarf.DW_AT_type).Data.(dwSym))
tname := d.ldr.SymName(elemgotype)
elemname := tname[5:]
elemtype := d.walksymtypedef(d.defgotype(d.lookupOrDiag(tname)))
// sudog<T>
dwss := d.mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "sudog", elemname, "", func(dws *dwarf.DWDie) {
d.copychildren(ctxt, dws, sudog)
d.substitutetype(dws, "elem", d.defptrto(elemtype))
newattr(dws, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, int64(sudogsize), nil)
})
// waitq<T>
dwws := d.mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "waitq", elemname, "", func(dww *dwarf.DWDie) {
d.copychildren(ctxt, dww, waitq)
d.substitutetype(dww, "first", d.defptrto(dwss))
d.substitutetype(dww, "last", d.defptrto(dwss))
newattr(dww, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(waitq, dwarf.DW_AT_byte_size).Value, nil)
})
// hchan<T>
dwhs := d.mkinternaltype(ctxt, dwarf.DW_ABRV_STRUCTTYPE, "hchan", elemname, "", func(dwh *dwarf.DWDie) {
d.copychildren(ctxt, dwh, hchan)
d.substitutetype(dwh, "recvq", dwws)
d.substitutetype(dwh, "sendq", dwws)
newattr(dwh, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, getattr(hchan, dwarf.DW_AT_byte_size).Value, nil)
})
d.newrefattr(die, dwarf.DW_AT_type, d.defptrto(dwhs))
}
}
// createUnitLength creates the initial length field with value v and update
// offset of unit_length if needed.
func (d *dwctxt) createUnitLength(su *loader.SymbolBuilder, v uint64) {
if isDwarf64(d.linkctxt) {
su.AddUint32(d.arch, 0xFFFFFFFF)
}
d.addDwarfAddrField(su, v)
}
// addDwarfAddrField adds a DWARF field in DWARF 64bits or 32bits.
func (d *dwctxt) addDwarfAddrField(sb *loader.SymbolBuilder, v uint64) {
if isDwarf64(d.linkctxt) {
sb.AddUint(d.arch, v)
} else {
sb.AddUint32(d.arch, uint32(v))
}
}
// addDwarfAddrRef adds a DWARF pointer in DWARF 64bits or 32bits.
func (d *dwctxt) addDwarfAddrRef(sb *loader.SymbolBuilder, t loader.Sym) {
if isDwarf64(d.linkctxt) {
d.adddwarfref(sb, t, 8)
} else {
d.adddwarfref(sb, t, 4)
}
}
// calcCompUnitRanges calculates the PC ranges of the compilation units.
func (d *dwctxt) calcCompUnitRanges() {
var prevUnit *sym.CompilationUnit
for _, s := range d.linkctxt.Textp {
sym := loader.Sym(s)
fi := d.ldr.FuncInfo(sym)
if !fi.Valid() {
continue
}
// Skip linker-created functions (ex: runtime.addmoduledata), since they
// don't have DWARF to begin with.
unit := d.ldr.SymUnit(sym)
if unit == nil {
continue
}
// 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.
sval := d.ldr.SymValue(sym)
u0val := d.ldr.SymValue(loader.Sym(unit.Textp[0]))
if prevUnit != unit {
unit.PCs = append(unit.PCs, dwarf.Range{Start: sval - u0val})
prevUnit = unit
}
unit.PCs[len(unit.PCs)-1].End = sval - u0val + int64(len(d.ldr.Data(sym)))
}
}
func movetomodule(ctxt *Link, parent *dwarf.DWDie) {
die := ctxt.runtimeCU.DWInfo.Child
if die == nil {
ctxt.runtimeCU.DWInfo.Child = parent.Child
return
}
for die.Link != nil {
die = die.Link
}
die.Link = parent.Child
}
/*
* 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
)
/*
* 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 (d *dwctxt) importInfoSymbol(dsym loader.Sym) {
d.ldr.SetAttrReachable(dsym, true)
d.ldr.SetAttrNotInSymbolTable(dsym, true)
dst := d.ldr.SymType(dsym)
if dst != sym.SDWARFCONST && dst != sym.SDWARFABSFCN {
log.Fatalf("error: DWARF info sym %d/%s with incorrect type %s", dsym, d.ldr.SymName(dsym), d.ldr.SymType(dsym).String())
}
relocs := d.ldr.Relocs(dsym)
for i := 0; i < relocs.Count(); i++ {
r := relocs.At(i)
if r.Type() != objabi.R_DWARFSECREF {
continue
}
rsym := r.Sym()
// If there is an entry for the symbol in our rtmap, then it
// means we've processed the type already, and can skip this one.
if _, ok := d.rtmap[rsym]; ok {
// type already generated
continue
}
// FIXME: is there a way we could avoid materializing the
// symbol name here?
sn := d.ldr.SymName(rsym)
tn := sn[len(dwarf.InfoPrefix):]
ts := d.ldr.Lookup("type:"+tn, 0)
d.defgotype(ts)
}
}
func expandFile(fname string) string {
fname = strings.TrimPrefix(fname, src.FileSymPrefix)
return expandGoroot(fname)
}
// writeDirFileTables emits the portion of the DWARF line table
// prologue containing the include directories and file names,
// described in section 6.2.4 of the DWARF 4 standard. It walks the
// filepaths for the unit to discover any common directories, which
// are emitted to the directory table first, then the file table is
// emitted after that.
func (d *dwctxt) writeDirFileTables(unit *sym.CompilationUnit, lsu *loader.SymbolBuilder) {
type fileDir struct {
base string
dir int
}
dirNums := make(map[string]int)
dirs := []string{""}
files := []fileDir{}
// Preprocess files to collect directories. This assumes that the
// file table is already de-duped.
for i, name := range unit.FileTable {
name := expandFile(name)
if len(name) == 0 {
// Can't have empty filenames, and having a unique
// filename is quite useful for debugging.
name = fmt.Sprintf("<missing>_%d", i)
}
// Note the use of "path" here and not "filepath". The compiler
// hard-codes to use "/" in DWARF paths (even for Windows), so we
// want to maintain that here.
file := path.Base(name)
dir := path.Dir(name)
dirIdx, ok := dirNums[dir]
if !ok && dir != "." {
dirIdx = len(dirNums) + 1
dirNums[dir] = dirIdx
dirs = append(dirs, dir)
}
files = append(files, fileDir{base: file, dir: dirIdx})
// 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(name, "runtime/proc.go"); i >= 0 && unit.Lib.Pkg == "runtime" {
d.dwmu.Lock()
if gdbscript == "" {
k := strings.Index(name, "runtime/proc.go")
gdbscript = name[:k] + "runtime/runtime-gdb.py"
}
d.dwmu.Unlock()
}
}
// Emit directory section. This is a series of nul terminated
// strings, followed by a single zero byte.
lsDwsym := dwSym(lsu.Sym())
for k := 1; k < len(dirs); k++ {
d.AddString(lsDwsym, dirs[k])
}
lsu.AddUint8(0) // terminator
// Emit file section.
for k := 0; k < len(files); k++ {
d.AddString(lsDwsym, files[k].base)
dwarf.Uleb128put(d, lsDwsym, int64(files[k].dir))
lsu.AddUint8(0) // mtime
lsu.AddUint8(0) // length
}
lsu.AddUint8(0) // terminator
}
// writelines collects up and chains together the symbols needed to
// form the DWARF line table for the specified compilation unit,
// returning a list of symbols. The returned list will include an
// initial symbol containing the line table header and prologue (with
// file table), then a series of compiler-emitted line table symbols
// (one per live function), and finally an epilog symbol containing an
// end-of-sequence operator. The prologue and epilog symbols are passed
// in (having been created earlier); here we add content to them.
func (d *dwctxt) writelines(unit *sym.CompilationUnit, lineProlog loader.Sym) []loader.Sym {
is_stmt := uint8(1) // initially = recommended default_is_stmt = 1, tracks is_stmt toggles.
unitstart := int64(-1)
headerstart := int64(-1)
headerend := int64(-1)
syms := make([]loader.Sym, 0, len(unit.Textp)+2)
syms = append(syms, lineProlog)
lsu := d.ldr.MakeSymbolUpdater(lineProlog)
lsDwsym := dwSym(lineProlog)
newattr(unit.DWInfo, dwarf.DW_AT_stmt_list, dwarf.DW_CLS_PTR, 0, lsDwsym)
// Write .debug_line Line Number Program Header (sec 6.2.4)
// Fields marked with (*) must be changed for 64-bit dwarf
unitLengthOffset := lsu.Size()
d.createUnitLength(lsu, 0) // unit_length (*), filled in at end
unitstart = lsu.Size()
lsu.AddUint16(d.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 := lsu.Size()
d.addDwarfAddrField(lsu, 0) // header_length (*), filled in at end
headerstart = lsu.Size()
// cpos == unitstart + 4 + 2 + 4
lsu.AddUint8(1) // minimum_instruction_length
lsu.AddUint8(is_stmt) // default_is_stmt
lsu.AddUint8(LINE_BASE & 0xFF) // line_base
lsu.AddUint8(LINE_RANGE) // line_range
lsu.AddUint8(OPCODE_BASE) // opcode_base
lsu.AddUint8(0) // standard_opcode_lengths[1]
lsu.AddUint8(1) // standard_opcode_lengths[2]
lsu.AddUint8(1) // standard_opcode_lengths[3]
lsu.AddUint8(1) // standard_opcode_lengths[4]
lsu.AddUint8(1) // standard_opcode_lengths[5]
lsu.AddUint8(0) // standard_opcode_lengths[6]
lsu.AddUint8(0) // standard_opcode_lengths[7]
lsu.AddUint8(0) // standard_opcode_lengths[8]
lsu.AddUint8(1) // standard_opcode_lengths[9]
lsu.AddUint8(0) // standard_opcode_lengths[10]
// Call helper to emit dir and file sections.
d.writeDirFileTables(unit, lsu)
// capture length at end of file names.
headerend = lsu.Size()
unitlen := lsu.Size() - unitstart
// Output the state machine for each function remaining.
for _, s := range unit.Textp {
fnSym := loader.Sym(s)
_, _, _, lines := d.ldr.GetFuncDwarfAuxSyms(fnSym)
// Chain the line symbol onto the list.
if lines != 0 {
syms = append(syms, lines)
unitlen += int64(len(d.ldr.Data(lines)))
}
}
if d.linkctxt.HeadType == objabi.Haix {
addDwsectCUSize(".debug_line", unit.Lib.Pkg, uint64(unitlen))
}
if isDwarf64(d.linkctxt) {
lsu.SetUint(d.arch, unitLengthOffset+4, uint64(unitlen)) // +4 because of 0xFFFFFFFF
lsu.SetUint(d.arch, headerLengthOffset, uint64(headerend-headerstart))
} else {
lsu.SetUint32(d.arch, unitLengthOffset, uint32(unitlen))
lsu.SetUint32(d.arch, headerLengthOffset, uint32(headerend-headerstart))
}
return syms
}
// writepcranges generates the DW_AT_ranges table for compilation unit
// "unit", and returns a collection of ranges symbols (one for the
// compilation unit DIE itself and the remainder from functions in the unit).
func (d *dwctxt) writepcranges(unit *sym.CompilationUnit, base loader.Sym, pcs []dwarf.Range, rangeProlog loader.Sym) []loader.Sym {
syms := make([]loader.Sym, 0, len(unit.RangeSyms)+1)
syms = append(syms, rangeProlog)
rsu := d.ldr.MakeSymbolUpdater(rangeProlog)
rDwSym := dwSym(rangeProlog)
// Create PC ranges for the compilation unit DIE.
newattr(unit.DWInfo, dwarf.DW_AT_ranges, dwarf.DW_CLS_PTR, rsu.Size(), rDwSym)
newattr(unit.DWInfo, dwarf.DW_AT_low_pc, dwarf.DW_CLS_ADDRESS, 0, dwSym(base))
dwarf.PutBasedRanges(d, rDwSym, pcs)
// Collect up the ranges for functions in the unit.
rsize := uint64(rsu.Size())
for _, ls := range unit.RangeSyms {
s := loader.Sym(ls)
syms = append(syms, s)
rsize += uint64(d.ldr.SymSize(s))
}
if d.linkctxt.HeadType == objabi.Haix {
addDwsectCUSize(".debug_ranges", unit.Lib.Pkg, rsize)
}
return syms
}
/*
* 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 (d *dwctxt) writeframes(fs loader.Sym) dwarfSecInfo {
fsd := dwSym(fs)
fsu := d.ldr.MakeSymbolUpdater(fs)
fsu.SetType(sym.SDWARFSECT)
isdw64 := isDwarf64(d.linkctxt)
haslr := d.linkctxt.Arch.HasLR
// Length field is 4 bytes on Dwarf32 and 12 bytes on Dwarf64
lengthFieldSize := int64(4)
if isdw64 {
lengthFieldSize += 8
}
// Emit the CIE, Section 6.4.1
cieReserve := uint32(16)
if haslr {
cieReserve = 32
}
if isdw64 {
cieReserve += 4 // 4 bytes added for cid
}
d.createUnitLength(fsu, uint64(cieReserve)) // initial length, must be multiple of thearch.ptrsize
d.addDwarfAddrField(fsu, ^uint64(0)) // cid
fsu.AddUint8(3) // dwarf version (appendix F)
fsu.AddUint8(0) // augmentation ""
dwarf.Uleb128put(d, fsd, 1) // code_alignment_factor
dwarf.Sleb128put(d, fsd, dataAlignmentFactor) // all CFI offset calculations include multiplication with this factor
dwarf.Uleb128put(d, fsd, int64(thearch.Dwarfreglr)) // return_address_register
fsu.AddUint8(dwarf.DW_CFA_def_cfa) // Set the current frame address..
dwarf.Uleb128put(d, fsd, int64(thearch.Dwarfregsp)) // ...to use the value in the platform's SP register (defined in l.go)...
if haslr {
dwarf.Uleb128put(d, fsd, int64(0)) // ...plus a 0 offset.
fsu.AddUint8(dwarf.DW_CFA_same_value) // The platform's link register is unchanged during the prologue.
dwarf.Uleb128put(d, fsd, int64(thearch.Dwarfreglr))
fsu.AddUint8(dwarf.DW_CFA_val_offset) // The previous value...
dwarf.Uleb128put(d, fsd, int64(thearch.Dwarfregsp)) // ...of the platform's SP register...
dwarf.Uleb128put(d, fsd, int64(0)) // ...is CFA+0.
} else {
dwarf.Uleb128put(d, fsd, int64(d.arch.PtrSize)) // ...plus the word size (because the call instruction implicitly adds one word to the frame).
fsu.AddUint8(dwarf.DW_CFA_offset_extended) // The previous value...
dwarf.Uleb128put(d, fsd, int64(thearch.Dwarfreglr)) // ...of the return address...
dwarf.Uleb128put(d, fsd, int64(-d.arch.PtrSize)/dataAlignmentFactor) // ...is saved at [CFA - (PtrSize/4)].
}
pad := int64(cieReserve) + lengthFieldSize - int64(len(d.ldr.Data(fs)))
if pad < 0 {
Exitf("dwarf: cieReserve too small by %d bytes.", -pad)
}
internalExec := d.linkctxt.BuildMode == BuildModeExe && d.linkctxt.IsInternal()
addAddrPlus := loader.GenAddAddrPlusFunc(internalExec)
fsu.AddBytes(zeros[:pad])
var deltaBuf []byte
pcsp := obj.NewPCIter(uint32(d.arch.MinLC))
for _, s := range d.linkctxt.Textp {
fn := loader.Sym(s)
fi := d.ldr.FuncInfo(fn)
if !fi.Valid() {
continue
}
fpcsp := d.ldr.Pcsp(s)
// Emit a FDE, Section 6.4.1.
// First build the section contents into a byte buffer.
deltaBuf = deltaBuf[:0]
if haslr && fi.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(d.linkctxt.loader.Data(fpcsp)); !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) == int64(len(d.ldr.Data(fn))) {
nextpc--
if nextpc < pcsp.PC {
continue
}
}
spdelta := int64(pcsp.Value)
if !haslr {
// Return address has been pushed onto stack.
spdelta += int64(d.arch.PtrSize)
}
if haslr && !fi.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(d.arch, deltaBuf, int64(nextpc)-int64(pcsp.PC), spdelta)
}
pad := int(Rnd(int64(len(deltaBuf)), int64(d.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*d.arch.PtrSize + len(deltaBuf))
if isdw64 {
fdeLength += 4 // 4 bytes added for CIE pointer
}
d.createUnitLength(fsu, fdeLength)
if d.linkctxt.LinkMode == LinkExternal {
d.addDwarfAddrRef(fsu, fs)
} else {
d.addDwarfAddrField(fsu, 0) // CIE offset
}
addAddrPlus(fsu, d.arch, s, 0)
fsu.AddUintXX(d.arch, uint64(len(d.ldr.Data(fn))), d.arch.PtrSize) // address range
fsu.AddBytes(deltaBuf)
if d.linkctxt.HeadType == objabi.Haix {
addDwsectCUSize(".debug_frame", d.ldr.SymPkg(fn), fdeLength+uint64(lengthFieldSize))
}
}
return dwarfSecInfo{syms: []loader.Sym{fs}}
}
/*
* Walk DWarfDebugInfoEntries, and emit .debug_info
*/
const (
COMPUNITHEADERSIZE = 4 + 2 + 4 + 1
)
func (d *dwctxt) writeUnitInfo(u *sym.CompilationUnit, abbrevsym loader.Sym, infoEpilog loader.Sym) []loader.Sym {
syms := []loader.Sym{}
if len(u.Textp) == 0 && u.DWInfo.Child == nil && len(u.VarDIEs) == 0 {
return syms
}
compunit := u.DWInfo
s := d.dtolsym(compunit.Sym)
su := d.ldr.MakeSymbolUpdater(s)
// 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.
d.createUnitLength(su, 0) // unit_length (*), will be filled in later.
su.AddUint16(d.arch, 4) // dwarf version (appendix F)
// debug_abbrev_offset (*)
d.addDwarfAddrRef(su, abbrevsym)
su.AddUint8(uint8(d.arch.PtrSize)) // address_size
ds := dwSym(s)
dwarf.Uleb128put(d, ds, int64(compunit.Abbrev))
dwarf.PutAttrs(d, ds, compunit.Abbrev, compunit.Attr)
// This is an under-estimate; more will be needed for type DIEs.
cu := make([]loader.Sym, 0, len(u.AbsFnDIEs)+len(u.FuncDIEs))
cu = append(cu, s)
cu = append(cu, u.AbsFnDIEs...)
cu = append(cu, u.FuncDIEs...)
if u.Consts != 0 {
cu = append(cu, loader.Sym(u.Consts))
}
cu = append(cu, u.VarDIEs...)
var cusize int64
for _, child := range cu {
cusize += int64(len(d.ldr.Data(child)))
}
for die := compunit.Child; die != nil; die = die.Link {
l := len(cu)
lastSymSz := int64(len(d.ldr.Data(cu[l-1])))
cu = d.putdie(cu, die)
if lastSymSz != int64(len(d.ldr.Data(cu[l-1]))) {
// putdie will sometimes append directly to the last symbol of the list
cusize = cusize - lastSymSz + int64(len(d.ldr.Data(cu[l-1])))
}
for _, child := range cu[l:] {
cusize += int64(len(d.ldr.Data(child)))
}
}
culu := d.ldr.MakeSymbolUpdater(infoEpilog)
culu.AddUint8(0) // closes compilation unit DIE
cu = append(cu, infoEpilog)
cusize++
// Save size for AIX symbol table.
if d.linkctxt.HeadType == objabi.Haix {
addDwsectCUSize(".debug_info", d.getPkgFromCUSym(s), uint64(cusize))
}
if isDwarf64(d.linkctxt) {
cusize -= 12 // exclude the length field.
su.SetUint(d.arch, 4, uint64(cusize)) // 4 because of 0XFFFFFFFF
} else {
cusize -= 4 // exclude the length field.
su.SetUint32(d.arch, 0, uint32(cusize))
}
return append(syms, cu...)
}
func (d *dwctxt) writegdbscript() dwarfSecInfo {
// TODO (aix): make it available
if d.linkctxt.HeadType == objabi.Haix {
return dwarfSecInfo{}
}
if d.linkctxt.LinkMode == LinkExternal && d.linkctxt.HeadType == objabi.Hwindows && d.linkctxt.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 dwarfSecInfo{}
}
if gdbscript == "" {
return dwarfSecInfo{}
}
gs := d.ldr.CreateSymForUpdate(".debug_gdb_scripts", 0)
gs.SetType(sym.SDWARFSECT)
gs.AddUint8(GdbScriptPythonFileId)
gs.Addstring(gdbscript)
return dwarfSecInfo{syms: []loader.Sym{gs.Sym()}}
}
// FIXME: might be worth looking replacing this map with a function
// that switches based on symbol instead.
var prototypedies map[string]*dwarf.DWDie
func dwarfEnabled(ctxt *Link) bool {
if *FlagW { // disable dwarf
return false
}
if ctxt.HeadType == objabi.Hplan9 || ctxt.HeadType == objabi.Hjs || ctxt.HeadType == objabi.Hwasip1 {
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
}
// mkBuiltinType populates the dwctxt2 sym lookup maps for the
// newly created builtin type DIE 'typeDie'.
func (d *dwctxt) mkBuiltinType(ctxt *Link, abrv int, tname string) *dwarf.DWDie {
// create type DIE
die := d.newdie(&dwtypes, abrv, tname)
// Look up type symbol.
gotype := d.lookupOrDiag("type:" + tname)
// Map from die sym to type sym
ds := loader.Sym(die.Sym.(dwSym))
d.rtmap[ds] = gotype
// Map from type to def sym
d.tdmap[gotype] = ds
return die
}
// dwarfVisitFunction takes a function (text) symbol and processes the
// subprogram DIE for the function and picks up any other DIEs
// (absfns, types) that it references.
func (d *dwctxt) dwarfVisitFunction(fnSym loader.Sym, unit *sym.CompilationUnit) {
// The DWARF subprogram DIE symbol is listed as an aux sym
// of the text (fcn) symbol, so ask the loader to retrieve it,
// as well as the associated range symbol.
infosym, _, rangesym, _ := d.ldr.GetFuncDwarfAuxSyms(fnSym)
if infosym == 0 {
return
}
d.ldr.SetAttrNotInSymbolTable(infosym, true)
d.ldr.SetAttrReachable(infosym, true)
unit.FuncDIEs = append(unit.FuncDIEs, sym.LoaderSym(infosym))
if rangesym != 0 {
d.ldr.SetAttrNotInSymbolTable(rangesym, true)
d.ldr.SetAttrReachable(rangesym, true)
unit.RangeSyms = append(unit.RangeSyms, sym.LoaderSym(rangesym))
}
// Walk the relocations of the subprogram DIE symbol to discover
// references to abstract function DIEs, Go type DIES, and
// (via R_USETYPE relocs) types that were originally assigned to
// locals/params but were optimized away.
drelocs := d.ldr.Relocs(infosym)
for ri := 0; ri < drelocs.Count(); ri++ {
r := drelocs.At(ri)
// Look for "use type" relocs.
if r.Type() == objabi.R_USETYPE {
d.defgotype(r.Sym())
continue
}
if r.Type() != objabi.R_DWARFSECREF {
continue
}
rsym := r.Sym()
rst := d.ldr.SymType(rsym)
// Look for abstract function references.
if rst == sym.SDWARFABSFCN {
if !d.ldr.AttrOnList(rsym) {
// abstract function
d.ldr.SetAttrOnList(rsym, true)
unit.AbsFnDIEs = append(unit.AbsFnDIEs, sym.LoaderSym(rsym))
d.importInfoSymbol(rsym)
}
continue
}
// Look for type references.
if rst != sym.SDWARFTYPE && rst != sym.Sxxx {
continue
}
if _, ok := d.rtmap[rsym]; ok {
// type already generated
continue
}
rsn := d.ldr.SymName(rsym)
tn := rsn[len(dwarf.InfoPrefix):]
ts := d.ldr.Lookup("type:"+tn, 0)
d.defgotype(ts)
}
}
// 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
}
d := &dwctxt{
linkctxt: ctxt,
ldr: ctxt.loader,
arch: ctxt.Arch,
tmap: make(map[string]loader.Sym),
tdmap: make(map[loader.Sym]loader.Sym),
rtmap: make(map[loader.Sym]loader.Sym),
}
d.typeRuntimeEface = d.lookupOrDiag("type:runtime.eface")
d.typeRuntimeIface = d.lookupOrDiag("type:runtime.iface")
if ctxt.HeadType == objabi.Haix {
// Initial map used to store package size for each DWARF section.
dwsectCUSize = make(map[string]uint64)
}
// For ctxt.Diagnostic messages.
newattr(&dwtypes, dwarf.DW_AT_name, dwarf.DW_CLS_STRING, int64(len("dwtypes")), "dwtypes")
// Unspecified type. There are no references to this in the symbol table.
d.newdie(&dwtypes, dwarf.DW_ABRV_NULLTYPE, "<unspecified>")
// Some types that must exist to define other ones (uintptr in particular
// is needed for array size)
unsafeptrDie := d.mkBuiltinType(ctxt, dwarf.DW_ABRV_BARE_PTRTYPE, "unsafe.Pointer")
newattr(unsafeptrDie, dwarf.DW_AT_go_runtime_type, dwarf.DW_CLS_GO_TYPEREF, 0, dwSym(d.lookupOrDiag("type:unsafe.Pointer")))
uintptrDie := d.mkBuiltinType(ctxt, dwarf.DW_ABRV_BASETYPE, "uintptr")
newattr(uintptrDie, dwarf.DW_AT_encoding, dwarf.DW_CLS_CONSTANT, dwarf.DW_ATE_unsigned, 0)
newattr(uintptrDie, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, int64(d.arch.PtrSize), 0)
newattr(uintptrDie, dwarf.DW_AT_go_kind, dwarf.DW_CLS_CONSTANT, int64(abi.Uintptr), 0)
newattr(uintptrDie, dwarf.DW_AT_go_runtime_type, dwarf.DW_CLS_GO_TYPEREF, 0, dwSym(d.lookupOrDiag("type:uintptr")))
d.uintptrInfoSym = d.mustFind("uintptr")
// Prototypes needed for type synthesis.
prototypedies = map[string]*dwarf.DWDie{
"type:runtime.stringStructDWARF": nil,
"type:runtime.slice": nil,
"type:runtime.sudog": nil,
"type:runtime.waitq": nil,
"type:runtime.hchan": nil,
}
if buildcfg.Experiment.SwissMap {
prototypedies["type:internal/runtime/maps.Map"] = nil
prototypedies["type:internal/runtime/maps.table"] = nil
prototypedies["type:internal/runtime/maps.groupsReference"] = nil
} else {
prototypedies["type:runtime.hmap"] = nil
prototypedies["type:runtime.bmap"] = nil
}
// Needed by the prettyprinter code for interface inspection.
for _, typ := range []string{
"type:internal/abi.Type",
"type:internal/abi.ArrayType",
"type:internal/abi.ChanType",
"type:internal/abi.FuncType",
"type:internal/abi.PtrType",
"type:internal/abi.SliceType",
"type:internal/abi.StructType",
"type:internal/abi.InterfaceType",
"type:internal/abi.ITab",
"type:internal/abi.Imethod"} {
d.defgotype(d.lookupOrDiag(typ))
}
if buildcfg.Experiment.SwissMap {
d.defgotype(d.lookupOrDiag("type:internal/abi.SwissMapType"))
} else {
d.defgotype(d.lookupOrDiag("type:internal/abi.OldMapType"))
}
// fake root DIE for compile unit DIEs
var dwroot dwarf.DWDie
flagVariants := make(map[string]bool)
for _, lib := range ctxt.Library {
consts := d.ldr.Lookup(dwarf.ConstInfoPrefix+lib.Pkg, 0)
for _, unit := range lib.Units {
// We drop the constants into the first CU.
if consts != 0 {
unit.Consts = sym.LoaderSym(consts)
d.importInfoSymbol(consts)
consts = 0
}
ctxt.compUnits = append(ctxt.compUnits, unit)
// We need at least one runtime unit.
if unit.Lib.Pkg == "runtime" {
ctxt.runtimeCU = unit
}
cuabrv := dwarf.DW_ABRV_COMPUNIT
if len(unit.Textp) == 0 {
cuabrv = dwarf.DW_ABRV_COMPUNIT_TEXTLESS
}
unit.DWInfo = d.newdie(&dwroot, cuabrv, unit.Lib.Pkg)
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)
var peData []byte
if producerExtra := d.ldr.Lookup(dwarf.CUInfoPrefix+"producer."+unit.Lib.Pkg, 0); producerExtra != 0 {
peData = d.ldr.Data(producerExtra)
}
producer := "Go cmd/compile " + buildcfg.Version
if len(peData) > 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(peData)
flagVariants[string(peData)] = true
} else {
flagVariants[""] = true
}
newattr(unit.DWInfo, dwarf.DW_AT_producer, dwarf.DW_CLS_STRING, int64(len(producer)), producer)
var pkgname string
if pnSymIdx := d.ldr.Lookup(dwarf.CUInfoPrefix+"packagename."+unit.Lib.Pkg, 0); pnSymIdx != 0 {
pnsData := d.ldr.Data(pnSymIdx)
pkgname = string(pnsData)
}
newattr(unit.DWInfo, dwarf.DW_AT_go_package_name, dwarf.DW_CLS_STRING, int64(len(pkgname)), pkgname)
// Scan all functions in this compilation unit, create
// DIEs for all referenced types, find all referenced
// abstract functions, visit range symbols. Note that
// Textp has been dead-code-eliminated already.
for _, s := range unit.Textp {
d.dwarfVisitFunction(loader.Sym(s), unit)
}
}
}
// 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
}
// Make a pass through all data symbols, looking for those
// corresponding to reachable, Go-generated, user-visible
// global variables. For each global of this sort, locate
// the corresponding compiler-generated DIE symbol and tack
// it onto the list associated with the unit.
// Also looks for dictionary symbols and generates DIE symbols for each
// type they reference.
for idx := loader.Sym(1); idx < loader.Sym(d.ldr.NDef()); idx++ {
if !d.ldr.AttrReachable(idx) ||
d.ldr.AttrNotInSymbolTable(idx) ||
d.ldr.SymVersion(idx) >= sym.SymVerStatic {
continue
}
t := d.ldr.SymType(idx)
switch {
case t.IsRODATA(), t.IsDATA(), t.IsNOPTRDATA(),
t == sym.STYPE, t == sym.SBSS, t == sym.SNOPTRBSS, t == sym.STLSBSS:
// ok
default:
continue
}
// Skip things with no type, unless it's a dictionary
gt := d.ldr.SymGoType(idx)
if gt == 0 {
if t == sym.SRODATA {
if d.ldr.IsDict(idx) {
// This is a dictionary, make sure that all types referenced by this dictionary are reachable
relocs := d.ldr.Relocs(idx)
for i := 0; i < relocs.Count(); i++ {
reloc := relocs.At(i)
if reloc.Type() == objabi.R_USEIFACE {
d.defgotype(reloc.Sym())
}
}
}
}
continue
}
// Skip file local symbols (this includes static tmps, stack
// object symbols, and local symbols in assembler src files).
if d.ldr.IsFileLocal(idx) {
continue
}
// Find compiler-generated DWARF info sym for global in question,
// and tack it onto the appropriate unit. Note that there are
// circumstances under which we can't find the compiler-generated
// symbol-- this typically happens as a result of compiler options
// (e.g. compile package X with "-dwarf=0").
varDIE := d.ldr.GetVarDwarfAuxSym(idx)
if varDIE != 0 {
unit := d.ldr.SymUnit(idx)
d.defgotype(gt)
unit.VarDIEs = append(unit.VarDIEs, sym.LoaderSym(varDIE))
}
}
d.synthesizestringtypes(ctxt, dwtypes.Child)
d.synthesizeslicetypes(ctxt, dwtypes.Child)
d.synthesizemaptypes(ctxt, dwtypes.Child)
d.synthesizechantypes(ctxt, dwtypes.Child)
}
// dwarfGenerateDebugSyms constructs debug_line, debug_frame, and
// debug_loc. It also writes out the debug_info section using symbols
// generated in dwarfGenerateDebugInfo2.
func dwarfGenerateDebugSyms(ctxt *Link) {
if !dwarfEnabled(ctxt) {
return
}
d := &dwctxt{
linkctxt: ctxt,
ldr: ctxt.loader,
arch: ctxt.Arch,
dwmu: new(sync.Mutex),
}
d.dwarfGenerateDebugSyms()
}
// dwUnitSyms stores input and output symbols for DWARF generation
// for a given compilation unit.
type dwUnitSyms struct {
// Inputs for a given unit.
lineProlog loader.Sym
rangeProlog loader.Sym
infoEpilog loader.Sym
// Outputs for a given unit.
linesyms []loader.Sym
infosyms []loader.Sym
locsyms []loader.Sym
rangessyms []loader.Sym
}
// dwUnitPortion assembles the DWARF content for a given compilation
// unit: debug_info, debug_lines, debug_ranges, debug_loc (debug_frame
// is handled elsewhere). Order is important; the calls to writelines
// and writepcranges below make updates to the compilation unit DIE,
// hence they have to happen before the call to writeUnitInfo.
func (d *dwctxt) dwUnitPortion(u *sym.CompilationUnit, abbrevsym loader.Sym, us *dwUnitSyms) {
if u.DWInfo.Abbrev != dwarf.DW_ABRV_COMPUNIT_TEXTLESS {
us.linesyms = d.writelines(u, us.lineProlog)
base := loader.Sym(u.Textp[0])
us.rangessyms = d.writepcranges(u, base, u.PCs, us.rangeProlog)
us.locsyms = d.collectUnitLocs(u)
}
us.infosyms = d.writeUnitInfo(u, abbrevsym, us.infoEpilog)
}
func (d *dwctxt) dwarfGenerateDebugSyms() {
abbrevSec := d.writeabbrev()
dwarfp = append(dwarfp, abbrevSec)
d.calcCompUnitRanges()
slices.SortFunc(d.linkctxt.compUnits, compilationUnitByStartPCCmp)
// 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.
for _, u := range d.linkctxt.compUnits {
reversetree(&u.DWInfo.Child)
}
reversetree(&dwtypes.Child)
movetomodule(d.linkctxt, &dwtypes)
mkSecSym := func(name string) loader.Sym {
s := d.ldr.CreateSymForUpdate(name, 0)
s.SetType(sym.SDWARFSECT)
s.SetReachable(true)
return s.Sym()
}
mkAnonSym := func(kind sym.SymKind) loader.Sym {
s := d.ldr.MakeSymbolUpdater(d.ldr.CreateExtSym("", 0))
s.SetType(kind)
s.SetReachable(true)
return s.Sym()
}
// Create the section symbols.
frameSym := mkSecSym(".debug_frame")
locSym := mkSecSym(".debug_loc")
lineSym := mkSecSym(".debug_line")
rangesSym := mkSecSym(".debug_ranges")
infoSym := mkSecSym(".debug_info")
// Create the section objects
lineSec := dwarfSecInfo{syms: []loader.Sym{lineSym}}
locSec := dwarfSecInfo{syms: []loader.Sym{locSym}}
rangesSec := dwarfSecInfo{syms: []loader.Sym{rangesSym}}
frameSec := dwarfSecInfo{syms: []loader.Sym{frameSym}}
infoSec := dwarfSecInfo{syms: []loader.Sym{infoSym}}
// Create any new symbols that will be needed during the
// parallel portion below.
ncu := len(d.linkctxt.compUnits)
unitSyms := make([]dwUnitSyms, ncu)
for i := 0; i < ncu; i++ {
us := &unitSyms[i]
us.lineProlog = mkAnonSym(sym.SDWARFLINES)
us.rangeProlog = mkAnonSym(sym.SDWARFRANGE)
us.infoEpilog = mkAnonSym(sym.SDWARFFCN)
}
var wg sync.WaitGroup
sema := make(chan struct{}, runtime.GOMAXPROCS(0))
// Kick off generation of .debug_frame, since it doesn't have
// any entanglements and can be started right away.
wg.Add(1)
go func() {
sema <- struct{}{}
defer func() {
<-sema
wg.Done()
}()
frameSec = d.writeframes(frameSym)
}()
// Create a goroutine per comp unit to handle the generation that
// unit's portion of .debug_line, .debug_loc, .debug_ranges, and
// .debug_info.
wg.Add(len(d.linkctxt.compUnits))
for i := 0; i < ncu; i++ {
go func(u *sym.CompilationUnit, us *dwUnitSyms) {
sema <- struct{}{}
defer func() {
<-sema
wg.Done()
}()
d.dwUnitPortion(u, abbrevSec.secSym(), us)
}(d.linkctxt.compUnits[i], &unitSyms[i])
}
wg.Wait()
markReachable := func(syms []loader.Sym) []loader.Sym {
for _, s := range syms {
d.ldr.SetAttrNotInSymbolTable(s, true)
d.ldr.SetAttrReachable(s, true)
}
return syms
}
// Stitch together the results.
for i := 0; i < ncu; i++ {
r := &unitSyms[i]
lineSec.syms = append(lineSec.syms, markReachable(r.linesyms)...)
infoSec.syms = append(infoSec.syms, markReachable(r.infosyms)...)
locSec.syms = append(locSec.syms, markReachable(r.locsyms)...)
rangesSec.syms = append(rangesSec.syms, markReachable(r.rangessyms)...)
}
dwarfp = append(dwarfp, lineSec)
dwarfp = append(dwarfp, frameSec)
gdbScriptSec := d.writegdbscript()
if gdbScriptSec.secSym() != 0 {
dwarfp = append(dwarfp, gdbScriptSec)
}
dwarfp = append(dwarfp, infoSec)
if len(locSec.syms) > 1 {
dwarfp = append(dwarfp, locSec)
}
dwarfp = append(dwarfp, rangesSec)
// Check to make sure we haven't listed any symbols more than once
// in the info section. This used to be done by setting and
// checking the OnList attribute in "putdie", but that strategy
// was not friendly for concurrency.
seen := loader.MakeBitmap(d.ldr.NSym())
for _, s := range infoSec.syms {
if seen.Has(s) {
log.Fatalf("dwarf symbol %s listed multiple times",
d.ldr.SymName(s))
}
seen.Set(s)
}
}
func (d *dwctxt) collectUnitLocs(u *sym.CompilationUnit) []loader.Sym {
syms := []loader.Sym{}
for _, fn := range u.FuncDIEs {
relocs := d.ldr.Relocs(loader.Sym(fn))
for i := 0; i < relocs.Count(); i++ {
reloc := relocs.At(i)
if reloc.Type() != objabi.R_DWARFSECREF {
continue
}
rsym := reloc.Sym()
if d.ldr.SymType(rsym) == sym.SDWARFLOC {
syms = append(syms, rsym)
// One location list entry per function, but many relocations to it. Don't duplicate.
break
}
}
}
return syms
}
// Add DWARF section names to the section header string table, by calling add
// on each name. ELF only.
func dwarfaddshstrings(ctxt *Link, add func(string)) {
if *FlagW { // disable dwarf
return
}
secs := []string{"abbrev", "frame", "info", "loc", "line", "gdb_scripts", "ranges"}
for _, sec := range secs {
add(".debug_" + sec)
if ctxt.IsExternal() {
add(elfRelType + ".debug_" + sec)
}
}
}
func dwarfaddelfsectionsyms(ctxt *Link) {
if *FlagW { // disable dwarf
return
}
if ctxt.LinkMode != LinkExternal {
return
}
ldr := ctxt.loader
for _, si := range dwarfp {
s := si.secSym()
sect := ldr.SymSect(si.secSym())
putelfsectionsym(ctxt, ctxt.Out, s, sect.Elfsect.(*ElfShdr).shnum)
}
}
// dwarfcompress compresses the DWARF sections. Relocations are applied
// on the fly. After this, dwarfp will contain a different (new) set of
// symbols, and sections may have been replaced.
func dwarfcompress(ctxt *Link) {
// compressedSect is a helper type for parallelizing compression.
type compressedSect struct {
index int
compressed []byte
syms []loader.Sym
}
supported := ctxt.IsELF || ctxt.IsWindows() || ctxt.IsDarwin()
if !ctxt.compressDWARF || !supported || ctxt.IsExternal() {
return
}
var compressedCount int
resChannel := make(chan compressedSect)
for i := range dwarfp {
go func(resIndex int, syms []loader.Sym) {
resChannel <- compressedSect{resIndex, compressSyms(ctxt, syms), syms}
}(compressedCount, dwarfp[i].syms)
compressedCount++
}
res := make([]compressedSect, compressedCount)
for ; compressedCount > 0; compressedCount-- {
r := <-resChannel
res[r.index] = r
}
ldr := ctxt.loader
var newDwarfp []dwarfSecInfo
Segdwarf.Sections = Segdwarf.Sections[:0]
for _, z := range res {
s := z.syms[0]
if z.compressed == nil {
// Compression didn't help.
ds := dwarfSecInfo{syms: z.syms}
newDwarfp = append(newDwarfp, ds)
Segdwarf.Sections = append(Segdwarf.Sections, ldr.SymSect(s))
} else {
var compressedSegName string
if ctxt.IsELF {
compressedSegName = ldr.SymSect(s).Name
} else {
compressedSegName = ".zdebug_" + ldr.SymSect(s).Name[len(".debug_"):]
}
sect := addsection(ctxt.loader, ctxt.Arch, &Segdwarf, compressedSegName, 04)
sect.Align = int32(ctxt.Arch.Alignment)
sect.Length = uint64(len(z.compressed))
sect.Compressed = true
newSym := ldr.MakeSymbolBuilder(compressedSegName)
ldr.SetAttrReachable(s, true)
newSym.SetData(z.compressed)
newSym.SetSize(int64(len(z.compressed)))
ldr.SetSymSect(newSym.Sym(), sect)
ds := dwarfSecInfo{syms: []loader.Sym{newSym.Sym()}}
newDwarfp = append(newDwarfp, ds)
// compressed symbols are no longer needed.
for _, s := range z.syms {
ldr.SetAttrReachable(s, false)
ldr.FreeSym(s)
}
}
}
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 _, si := range dwarfp {
for _, s := range si.syms {
ldr.SetSymValue(s, int64(pos))
sect := ldr.SymSect(s)
if sect != prevSect {
sect.Vaddr = uint64(pos)
prevSect = sect
}
if ldr.SubSym(s) != 0 {
log.Fatalf("%s: unexpected sub-symbols", ldr.SymName(s))
}
pos += uint64(ldr.SymSize(s))
if ctxt.IsWindows() {
pos = uint64(Rnd(int64(pos), PEFILEALIGN))
}
}
}
Segdwarf.Length = pos - Segdwarf.Vaddr
}
func compilationUnitByStartPCCmp(a, b *sym.CompilationUnit) int {
switch {
case len(a.Textp) == 0 && len(b.Textp) == 0:
return strings.Compare(a.Lib.Pkg, b.Lib.Pkg)
case len(a.Textp) != 0 && len(b.Textp) == 0:
return -1
case len(a.Textp) == 0 && len(b.Textp) != 0:
return +1
default:
return cmp.Compare(a.PCs[0].Start, b.PCs[0].Start)
}
}
// 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 (d *dwctxt) getPkgFromCUSym(s loader.Sym) string {
return strings.TrimPrefix(d.ldr.SymName(s), dwarf.InfoPrefix+".pkg.")
}
// 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 dwsectCUSizeMu sync.Mutex
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 addDwsectCUSize(sname string, pkgname string, size uint64) {
dwsectCUSizeMu.Lock()
defer dwsectCUSizeMu.Unlock()
dwsectCUSize[sname+"."+pkgname] += size
}