[dev.debug] cmd/link: let the linker combine .debug_ranges, remove globals
The linker is pretty good at combining a bunch of symbols into a
section, so let it do .debug_ranges the normal way. Along the way,
remove a bunch of globals that were only used by one function that would
only be called once per invocation.
Change-Id: I1a528a438b193c41e7c444e8830516b07f11affc
Reviewed-on: https://go-review.googlesource.com/43890
Reviewed-by: Alessandro Arzilli <alessandro.arzilli@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/cmd/link/internal/ld/data.go b/src/cmd/link/internal/ld/data.go
index 4523323..bf219f7 100644
--- a/src/cmd/link/internal/ld/data.go
+++ b/src/cmd/link/internal/ld/data.go
@@ -592,15 +592,7 @@
}
case objabi.R_DWARFREF:
- var sectName string
- var vaddr int64
- switch {
- case r.Sym.Sect != nil:
- sectName = r.Sym.Sect.Name
- vaddr = int64(r.Sym.Sect.Vaddr)
- case r.Sym.Type == SDWARFRANGE:
- sectName = ".debug_ranges"
- default:
+ if r.Sym.Sect == nil {
Errorf(s, "missing DWARF section for relocation target %s", r.Sym.Name)
}
@@ -615,8 +607,8 @@
r.Type = objabi.R_ADDR
}
- r.Xsym = ctxt.Syms.ROLookup(sectName, 0)
- r.Xadd = r.Add + Symaddr(r.Sym) - vaddr
+ r.Xsym = ctxt.Syms.ROLookup(r.Sym.Sect.Name, 0)
+ r.Xadd = r.Add + Symaddr(r.Sym) - int64(r.Sym.Sect.Vaddr)
o = r.Xadd
rs = r.Xsym
@@ -625,7 +617,7 @@
}
break
}
- o = Symaddr(r.Sym) + r.Add - vaddr
+ o = Symaddr(r.Sym) + r.Add - int64(r.Sym.Sect.Vaddr)
case objabi.R_WEAKADDROFF:
if !r.Sym.Attr.Reachable() {
@@ -1843,9 +1835,9 @@
dwarfgeneratedebugsyms(ctxt)
- var s *Symbol
var i int
- for i, s = range dwarfp {
+ for ; i < len(dwarfp); i++ {
+ s := dwarfp[i]
if s.Type != SDWARFSECT {
break
}
@@ -1862,13 +1854,24 @@
}
checkdatsize(ctxt, datsize, SDWARFSECT)
- if i < len(dwarfp) {
- sect = addsection(&Segdwarf, ".debug_info", 04)
+ for i < len(dwarfp) {
+ curType := dwarfp[i].Type
+ var sect *Section
+ switch curType {
+ case SDWARFINFO:
+ sect = addsection(&Segdwarf, ".debug_info", 04)
+ case SDWARFRANGE:
+ sect = addsection(&Segdwarf, ".debug_ranges", 04)
+ default:
+ Errorf(dwarfp[i], "unknown DWARF section %v", curType)
+ }
+
sect.Align = 1
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
- for _, s := range dwarfp[i:] {
- if s.Type != SDWARFINFO {
+ for ; i < len(dwarfp); i++ {
+ s := dwarfp[i]
+ if s.Type != curType {
break
}
s.Sect = sect
@@ -1878,7 +1881,7 @@
datsize += s.Size
}
sect.Length = uint64(datsize) - sect.Vaddr
- checkdatsize(ctxt, datsize, SDWARFINFO)
+ checkdatsize(ctxt, datsize, curType)
}
/* number the sections */
diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index ba8ace5..9b11fdc 100644
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -67,26 +67,15 @@
r.Add = ofs
}
-/*
- * Offsets and sizes of the debug_* sections in the cout file.
- */
-var abbrevsym *Symbol
-var arangessec *Symbol
-var framesec *Symbol
-var infosec *Symbol
-var linesec *Symbol
-var rangesec *Symbol
-
var gdbscript string
var dwarfp []*Symbol
-func writeabbrev(ctxt *Link, syms []*Symbol) []*Symbol {
+func writeabbrev(ctxt *Link) *Symbol {
s := ctxt.Syms.Lookup(".debug_abbrev", 0)
s.Type = SDWARFSECT
- abbrevsym = s
Addbytes(s, dwarf.GetAbbrev())
- return append(syms, s)
+ return s
}
/*
@@ -993,13 +982,10 @@
func writelines(ctxt *Link, syms []*Symbol) ([]*Symbol, []*Symbol) {
var dwarfctxt dwarf.Context = dwctxt{ctxt}
- if linesec == nil {
- linesec = ctxt.Syms.Lookup(".debug_line", 0)
- }
- linesec.Type = SDWARFSECT
- linesec.R = linesec.R[:0]
+ ls := ctxt.Syms.Lookup(".debug_line", 0)
+ ls.Type = SDWARFSECT
+ ls.R = ls.R[:0]
- ls := linesec
syms = append(syms, ls)
var funcs []*Symbol
@@ -1019,7 +1005,7 @@
dwinfo = newdie(ctxt, &dwroot, dwarf.DW_ABRV_COMPUNIT, "go", 0)
newattr(dwinfo, dwarf.DW_AT_language, dwarf.DW_CLS_CONSTANT, int64(lang), 0)
- newattr(dwinfo, dwarf.DW_AT_stmt_list, dwarf.DW_CLS_PTR, 0, linesec)
+ newattr(dwinfo, dwarf.DW_AT_stmt_list, dwarf.DW_CLS_PTR, 0, ls)
newattr(dwinfo, dwarf.DW_AT_low_pc, dwarf.DW_CLS_ADDRESS, s.Value, s)
// OS X linker requires compilation dir or absolute path in comp unit name to output debug info.
compDir := getCompilationDir()
@@ -1178,12 +1164,9 @@
func writeframes(ctxt *Link, syms []*Symbol) []*Symbol {
var dwarfctxt dwarf.Context = dwctxt{ctxt}
- if framesec == nil {
- framesec = ctxt.Syms.Lookup(".debug_frame", 0)
- }
- framesec.Type = SDWARFSECT
- framesec.R = framesec.R[:0]
- fs := framesec
+ fs := ctxt.Syms.Lookup(".debug_frame", 0)
+ fs.Type = SDWARFSECT
+ fs.R = fs.R[:0]
syms = append(syms, fs)
// Emit the CIE, Section 6.4.1
@@ -1280,7 +1263,7 @@
// ptrsize: address range
Adduint32(ctxt, fs, uint32(4+2*SysArch.PtrSize+len(deltaBuf))) // length (excludes itself)
if Linkmode == LinkExternal {
- adddwarfref(ctxt, fs, framesec, 4)
+ adddwarfref(ctxt, fs, fs, 4)
} else {
Adduint32(ctxt, fs, 0) // CIE offset
}
@@ -1292,27 +1275,24 @@
}
func writeranges(ctxt *Link, syms []*Symbol) []*Symbol {
- if rangesec == nil {
- rangesec = ctxt.Syms.Lookup(".debug_ranges", 0)
- }
- rangesec.Type = SDWARFSECT
- rangesec.Attr |= AttrReachable
- rangesec.R = rangesec.R[:0]
-
+ empty := true
for _, s := range ctxt.Textp {
rangeSym := ctxt.Syms.Lookup(dwarf.RangePrefix+s.Name, int(s.Version))
- rangeSym.Attr |= AttrReachable
- rangeSym.Type = SDWARFRANGE
- rangeSym.Value = rangesec.Size
- rangesec.P = append(rangesec.P, rangeSym.P...)
- for _, r := range rangeSym.R {
- r.Off += int32(rangesec.Size)
- rangesec.R = append(rangesec.R, r)
+ if rangeSym.Size == 0 {
+ continue
}
- rangesec.Size += rangeSym.Size
+ rangeSym.Attr |= AttrReachable | AttrNotInSymbolTable
+ rangeSym.Type = SDWARFRANGE
+ syms = append(syms, rangeSym)
+ empty = false
}
- if rangesec.Size > 0 {
+ if !empty {
// PE does not like empty sections
+ rangesec := ctxt.Syms.Lookup(".debug_ranges", 0)
+ rangesec.Type = SDWARFRANGE
+ rangesec.Attr |= AttrReachable
+ rangesec.R = rangesec.R[:0]
+
syms = append(syms, rangesec)
}
return syms
@@ -1325,18 +1305,14 @@
COMPUNITHEADERSIZE = 4 + 2 + 4 + 1
)
-func writeinfo(ctxt *Link, syms []*Symbol, funcs []*Symbol) []*Symbol {
- if infosec == nil {
- infosec = ctxt.Syms.Lookup(".debug_info", 0)
- }
+func writeinfo(ctxt *Link, syms []*Symbol, funcs []*Symbol, abbrevsym *Symbol) []*Symbol {
+ infosec := ctxt.Syms.Lookup(".debug_info", 0)
infosec.R = infosec.R[:0]
infosec.Type = SDWARFINFO
infosec.Attr |= AttrReachable
syms = append(syms, infosec)
- if arangessec == nil {
- arangessec = ctxt.Syms.Lookup(".dwarfaranges", 0)
- }
+ arangessec := ctxt.Syms.Lookup(".dwarfaranges", 0)
arangessec.R = arangessec.R[:0]
var dwarfctxt dwarf.Context = dwctxt{ctxt}
@@ -1577,10 +1553,10 @@
genasmsym(ctxt, defdwsymb)
- syms := writeabbrev(ctxt, nil)
+ abbrev := writeabbrev(ctxt)
+ syms := []*Symbol{abbrev}
syms, funcs := writelines(ctxt, syms)
syms = writeframes(ctxt, syms)
- syms = writeranges(ctxt, syms)
synthesizestringtypes(ctxt, dwtypes.Child)
synthesizeslicetypes(ctxt, dwtypes.Child)
@@ -1596,13 +1572,14 @@
// Need to reorder symbols so SDWARFINFO is after all SDWARFSECT
// (but we need to generate dies before writepub)
- infosyms := writeinfo(ctxt, nil, funcs)
+ infosyms := writeinfo(ctxt, nil, funcs, abbrev)
syms = writepub(ctxt, ".debug_pubnames", ispubname, syms)
syms = writepub(ctxt, ".debug_pubtypes", ispubtype, syms)
syms = writearanges(ctxt, syms)
syms = writegdbscript(ctxt, syms)
syms = append(syms, infosyms...)
+ syms = writeranges(ctxt, syms)
dwarfp = syms
}
