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cmd/compile: output DWARF lexical blocks for local variables

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Change compiler and linker to emit DWARF lexical blocks in debug_info.
Version of debug_info is updated from DWARF v.2 to DWARF v.3 since version 2
does not allow lexical blocks with discontinuous ranges.

Second attempt at https://go-review.googlesource.com/#/c/29591/

Remaining open problems:
- scope information is removed from inlined functions
- variables in debug_info do not have DW_AT_start_scope attributes so a
variable will shadow other variables with the same name as soon as its
containing scope begins, before its declaration.

Updates golang/go#12899, golang/go#6913

Change-Id: I0e260a45b564d14a87b88974eb16c5387cb410a5
Reviewed-on: https://go-review.googlesource.com/36879
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Alessandro Arzilli 2017-03-07 18:59:14 +01:00 • committed by Matthew Dempsky
parent 7165bcc6ba
commit c8b889cc48
21 changed files with 890 additions and 110 deletions
Download patch file Download diff file Expand all files Collapse all files

19
src/cmd/link/internal/ld/data.go
View file

@ -570,9 +570,18 @@ func relocsym(ctxt *Link, s *Symbol) {
}
case obj.R_DWARFREF:
if r.Sym.Sect == nil {
sectName := ""
vaddr := int64(0)
if r.Sym.Sect != nil {
sectName = r.Sym.Sect.Name
vaddr = int64(r.Sym.Sect.Vaddr)
} else if r.Sym.Type == obj.SDWARFRANGE {
sectName = ".debug_ranges"
vaddr = 0
} else {
Errorf(s, "missing DWARF section for relocation target %s", r.Sym.Name)
}
if Linkmode == LinkExternal {
r.Done = 0
// PE code emits IMAGE_REL_I386_SECREL and IMAGE_REL_AMD64_SECREL
@ -584,8 +593,9 @@ func relocsym(ctxt *Link, s *Symbol) {
r.Type = obj.R_ADDR
}
r.Xsym = ctxt.Syms.ROLookup(r.Sym.Sect.Name, 0)
r.Xadd = r.Add + Symaddr(r.Sym) - int64(r.Sym.Sect.Vaddr)
r.Xsym = ctxt.Syms.ROLookup(sectName, 0)
r.Xadd = r.Add + Symaddr(r.Sym) - vaddr
o = r.Xadd
rs = r.Xsym
if Iself && SysArch.Family == sys.AMD64 {
@ -593,7 +603,7 @@ func relocsym(ctxt *Link, s *Symbol) {
}
break
}
o = Symaddr(r.Sym) + r.Add - int64(r.Sym.Sect.Vaddr)
o = Symaddr(r.Sym) + r.Add - vaddr
case obj.R_WEAKADDROFF:
if !r.Sym.Attr.Reachable() {
@ -1822,6 +1832,7 @@ func (ctxt *Link) dodata() {
if s.Type != obj.SDWARFSECT {
break
}
sect = addsection(&Segdwarf, s.Name, 04)
sect.Align = 1
datsize = Rnd(datsize, int64(sect.Align))