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cmd/link: move Plt, Got fields in sym.Symbol to cold section

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The sym.Symbol 'Plt' and 'Got' field are used only with cgo and/or
external linking and are not needed for most symbols. Relocate them to
sym.AuxSymbol so as to shrink the main Symbol struct.

Updates #26186

Change-Id: I170d628a760be300a0c1f738f0998970e91ce3d6
Reviewed-on: https://go-review.googlesource.com/125478
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Than McIntosh 2018-07-17 15:36:30 -04:00
parent 2975914a1a
commit f78cc1324a
10 changed files with 100 additions and 68 deletions
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24
src/cmd/link/internal/x86/asm.go
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@ -197,7 +197,7 @@ func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool {
if targ.Type == sym.SDYNIMPORT {
addpltsym(ctxt, targ)
r.Sym = ctxt.Syms.Lookup(".plt", 0)
r.Add += int64(targ.Plt)
r.Add += int64(targ.Plt())
}
return true
@ -230,7 +230,7 @@ func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool {
addgotsym(ctxt, targ)
r.Type = objabi.R_CONST // write r->add during relocsym
r.Sym = nil
r.Add += int64(targ.Got)
r.Add += int64(targ.Got())
return true
case 256 + objabi.RelocType(elf.R_386_GOTOFF):
@ -261,7 +261,7 @@ func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool {
if targ.Type == sym.SDYNIMPORT {
addpltsym(ctxt, targ)
r.Sym = ctxt.Syms.Lookup(".plt", 0)
r.Add = int64(targ.Plt)
r.Add = int64(targ.Plt())
r.Type = objabi.R_PCREL
return true
}
@ -285,7 +285,7 @@ func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool {
addgotsym(ctxt, targ)
r.Sym = ctxt.Syms.Lookup(".got", 0)
r.Add += int64(targ.Got)
r.Add += int64(targ.Got())
r.Type = objabi.R_PCREL
return true
}
@ -303,7 +303,7 @@ func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool {
}
addpltsym(ctxt, targ)
r.Sym = ctxt.Syms.Lookup(".plt", 0)
r.Add = int64(targ.Plt)
r.Add = int64(targ.Plt())
return true
case objabi.R_ADDR:
@ -538,7 +538,7 @@ func elfsetupplt(ctxt *ld.Link) {
}
func addpltsym(ctxt *ld.Link, s *sym.Symbol) {
if s.Plt >= 0 {
if s.Plt() >= 0 {
return
}
@ -576,7 +576,7 @@ func addpltsym(ctxt *ld.Link, s *sym.Symbol) {
rel.AddUint32(ctxt.Arch, ld.ELF32_R_INFO(uint32(s.Dynid), uint32(elf.R_386_JMP_SLOT)))
s.Plt = int32(plt.Size - 16)
s.SetPlt(int32(plt.Size - 16))
} else if ctxt.HeadType == objabi.Hdarwin {
// Same laziness as in 6l.
@ -587,29 +587,29 @@ func addpltsym(ctxt *ld.Link, s *sym.Symbol) {
ctxt.Syms.Lookup(".linkedit.plt", 0).AddUint32(ctxt.Arch, uint32(s.Dynid))
// jmpq *got+size(IP)
s.Plt = int32(plt.Size)
s.SetPlt(int32(plt.Size))
plt.AddUint8(0xff)
plt.AddUint8(0x25)
plt.AddAddrPlus(ctxt.Arch, ctxt.Syms.Lookup(".got", 0), int64(s.Got))
plt.AddAddrPlus(ctxt.Arch, ctxt.Syms.Lookup(".got", 0), int64(s.Got()))
} else {
ld.Errorf(s, "addpltsym: unsupported binary format")
}
}
func addgotsym(ctxt *ld.Link, s *sym.Symbol) {
if s.Got >= 0 {
if s.Got() >= 0 {
return
}
ld.Adddynsym(ctxt, s)
got := ctxt.Syms.Lookup(".got", 0)
s.Got = int32(got.Size)
s.SetGot(int32(got.Size))
got.AddUint32(ctxt.Arch, 0)
if ctxt.IsELF {
rel := ctxt.Syms.Lookup(".rel", 0)
rel.AddAddrPlus(ctxt.Arch, got, int64(s.Got))
rel.AddAddrPlus(ctxt.Arch, got, int64(s.Got()))
rel.AddUint32(ctxt.Arch, ld.ELF32_R_INFO(uint32(s.Dynid), uint32(elf.R_386_GLOB_DAT)))
} else if ctxt.HeadType == objabi.Hdarwin {
ctxt.Syms.Lookup(".linkedit.got", 0).AddUint32(ctxt.Arch, uint32(s.Dynid))