[dev.link] cmd/link: stop emitting .debug_pubnames/.debug_pubtypes
Don't emit the .debug_pubnames/.debug_pubtypes sections. These sections
are not used by either GDB or Delve, and C++ compilers [notably GCC
and Clang] no longer emit the sections by default.
Change-Id: Ic3309755e88c8e1aa28a29366bc7f0df1748fe64
Reviewed-on: https://go-review.googlesource.com/c/go/+/237426
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index 7816251..da05d1b 100644
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -1518,7 +1518,7 @@
return syms
}
-func (d *dwctxt) writeinfo(units []*sym.CompilationUnit, abbrevsym loader.Sym, pubNames, pubTypes *pubWriter) dwarfSecInfo {
+func (d *dwctxt) writeinfo(units []*sym.CompilationUnit, abbrevsym loader.Sym) dwarfSecInfo {
infosec := d.ldr.LookupOrCreateSym(".debug_info", 0)
disu := d.ldr.MakeSymbolUpdater(infosec)
@@ -1535,9 +1535,6 @@
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.
@@ -1568,12 +1565,6 @@
l := len(cu)
lastSymSz := int64(len(d.ldr.Data(cu[l-1])))
cu = d.putdie(cu, die)
- if ispubname(die) {
- pubNames.add(die, cusize)
- }
- if ispubtype(die) {
- pubTypes.add(die, cusize)
- }
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])))
@@ -1598,87 +1589,12 @@
cusize -= 4 // exclude the length field.
su.SetUint32(d.arch, 0, uint32(cusize))
}
- pubNames.endCompUnit(compunit, uint32(cusize)+4)
- pubTypes.endCompUnit(compunit, uint32(cusize)+4)
syms = append(syms, cu...)
}
return dwarfSecInfo{syms: syms}
}
-/*
- * Emit .debug_pubnames/_types. _info must have been written before,
- * because we need die->offs and infoo/infosize;
- */
-
-type pubWriter struct {
- d *dwctxt
- s loader.Sym
- su *loader.SymbolBuilder
- sname string
-
- sectionstart int64
- culengthOff int64
-}
-
-func newPubWriter(d *dwctxt, sname string) *pubWriter {
- s := d.ldr.LookupOrCreateSym(sname, 0)
- u := d.ldr.MakeSymbolUpdater(s)
- u.SetType(sym.SDWARFSECT)
- return &pubWriter{d: d, s: s, su: u, sname: sname}
-}
-
-func (pw *pubWriter) beginCompUnit(compunit *dwarf.DWDie) {
- pw.sectionstart = pw.su.Size()
-
- // Write .debug_pubnames/types Header (sec 6.1.1)
- pw.d.createUnitLength(pw.su, 0) // unit_length (*), will be filled in later.
- pw.su.AddUint16(pw.d.arch, 2) // dwarf version (appendix F)
- pw.d.addDwarfAddrRef(pw.su, pw.d.dtolsym(compunit.Sym)) // debug_info_offset (of the Comp unit Header)
- pw.culengthOff = pw.su.Size()
- pw.d.addDwarfAddrField(pw.su, 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 pw.d.dtolsym(die.Sym) == 0 {
- fmt.Println("Missing sym for ", name)
- }
- pw.d.addDwarfAddrField(pw.su, uint64(offset))
- pw.su.Addstring(name)
-}
-
-func (pw *pubWriter) endCompUnit(compunit *dwarf.DWDie, culength uint32) {
- pw.d.addDwarfAddrField(pw.su, 0) // Null offset
-
- // On AIX, save the current size of this compilation unit.
- if pw.d.linkctxt.HeadType == objabi.Haix {
- saveDwsectCUSize(pw.sname, pw.d.getPkgFromCUSym(pw.d.dtolsym(compunit.Sym)), uint64(pw.su.Size()-pw.sectionstart))
- }
- if isDwarf64(pw.d.linkctxt) {
- pw.su.SetUint(pw.d.arch, pw.sectionstart+4, uint64(pw.su.Size()-pw.sectionstart)-12) // exclude the length field.
- pw.su.SetUint(pw.d.arch, pw.culengthOff, uint64(culength))
- } else {
- pw.su.SetUint32(pw.d.arch, pw.sectionstart, uint32(pw.su.Size()-pw.sectionstart)-4) // exclude the length field.
- pw.su.SetUint32(pw.d.arch, pw.culengthOff, culength)
- }
-}
-
-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
-}
-
func (d *dwctxt) writegdbscript() dwarfSecInfo {
// TODO (aix): make it available
if d.linkctxt.HeadType == objabi.Haix {
@@ -2019,9 +1935,9 @@
// every DIE constructed and convert the symbols.
}
-// 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 dwarfGenerateDebugInfo2.
+// 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
@@ -2070,15 +1986,10 @@
reversetree(&dwtypes.Child)
movetomodule(d.linkctxt, &dwtypes)
- pubNames := newPubWriter(d, ".debug_pubnames")
- pubTypes := newPubWriter(d, ".debug_pubtypes")
-
- infoSec := d.writeinfo(d.linkctxt.compUnits, abbrevSec.secSym(), pubNames, pubTypes)
+ infoSec := d.writeinfo(d.linkctxt.compUnits, abbrevSec.secSym())
framesSec := d.writeframes()
dwarfp = append(dwarfp, framesSec)
- dwarfp = append(dwarfp, dwarfSecInfo{syms: []loader.Sym{pubNames.s}})
- dwarfp = append(dwarfp, dwarfSecInfo{syms: []loader.Sym{pubTypes.s}})
gdbScriptSec := d.writegdbscript()
if gdbScriptSec.secSym() != 0 {
dwarfp = append(dwarfp, gdbScriptSec)
@@ -2142,7 +2053,7 @@
return
}
- secs := []string{"abbrev", "frame", "info", "loc", "line", "pubnames", "pubtypes", "gdb_scripts", "ranges"}
+ secs := []string{"abbrev", "frame", "info", "loc", "line", "gdb_scripts", "ranges"}
for _, sec := range secs {
shstrtab.Addstring(".debug_" + sec)
if ctxt.IsExternal() {
