cmd/link: move all FUNCDATA refs into go.func.*

This change moves all symbols referred to by FUNCDATA into go.func.* and go.funcrel.*. Surprisingly (because it inhibits some content-addressability), it shrinks binaries by a little bit, about 0.1%. This paves the way for a subsequent change to change FUNCDATA relocations to offsets. Change-Id: I70e487205073699f442192b0791cc92da5663057 Reviewed-on: https://go-review.googlesource.com/c/go/+/352189 Trust: Josh Bleecher Snyder <[email protected]> Run-TryBot: Josh Bleecher Snyder <[email protected]> TryBot-Result: Go Bot <[email protected]> Reviewed-by: Cherry Mui <[email protected]>
cloudflare · Oct 5, 2021 · cfd74f7 · cfd74f7
1 parent 7983830
commit cfd74f7
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Showing 2 changed files with 29 additions and 12 deletions.
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
@@ -408,7 +408,21 @@ func contentHashSection(s *LSym) byte {
  name := s.Name
  if s.IsPcdata() {
  return 'P'
- } else if strings.HasPrefix(name, "type.") {
+ }
+ if strings.HasPrefix(name, "runtime.gcbits.") {
+ return 'G' // gcbits
+ }
+ if strings.HasPrefix(name, "gcargs.") ||
+ strings.HasPrefix(name, "gclocals.") ||
+ strings.HasPrefix(name, "gclocals·") ||
+ strings.HasSuffix(name, ".opendefer") ||
+ strings.HasSuffix(name, ".arginfo0") ||
+ strings.HasSuffix(name, ".arginfo1") ||
+ strings.HasSuffix(name, ".args_stackmap") ||
+ strings.HasSuffix(name, ".stkobj") {
+ return 'F' // go.func.* or go.funcrel.*
+ }
+ if strings.HasPrefix(name, "type.") {
  return 'T'
  }
  return 0

diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
@@ -507,13 +507,9 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
  symgcbits = groupSym("runtime.gcbits.*", sym.SGCBITS)
  )
 
- var symgofuncrel loader.Sym
- if !ctxt.DynlinkingGo() {
- if ctxt.UseRelro() {
- symgofuncrel = groupSym("go.funcrel.*", sym.SGOFUNCRELRO)
- } else {
- symgofuncrel = symgofunc
- }
+ symgofuncrel := symgofunc
+ if ctxt.UseRelro() {
+ symgofuncrel = groupSym("go.funcrel.*", sym.SGOFUNCRELRO)
  }
 
  symt := ldr.CreateSymForUpdate("runtime.symtab", 0)
@@ -555,7 +551,7 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
  }
  if ctxt.UseRelro() {
  symGroupType[s] = sym.SGOFUNCRELRO
- if symgofuncrel != 0 {
+ if !ctxt.DynlinkingGo() {
  ldr.SetCarrierSym(s, symgofuncrel)
  }
  } else {
@@ -569,10 +565,17 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
  ldr.SymType(s) == sym.SGOFUNC && s != symgofunc, // inltree, see pcln.go
  strings.HasSuffix(name, ".opendefer"),
  strings.HasSuffix(name, ".arginfo0"),
- strings.HasSuffix(name, ".arginfo1"):
- symGroupType[s] = sym.SGOFUNC
+ strings.HasSuffix(name, ".arginfo1"),
+ strings.HasSuffix(name, ".args_stackmap"),
+ strings.HasSuffix(name, ".stkobj"):
  ldr.SetAttrNotInSymbolTable(s, true)
- ldr.SetCarrierSym(s, symgofunc)
+ if ctxt.UseRelro() && strings.HasSuffix(name, ".stkobj") {
+ symGroupType[s] = sym.SGOFUNCRELRO
+ ldr.SetCarrierSym(s, symgofuncrel)
+ } else {
+ symGroupType[s] = sym.SGOFUNC
+ ldr.SetCarrierSym(s, symgofunc)
+ }
  if ctxt.Debugvlog != 0 {
  align := ldr.SymAlign(s)
  liveness += (ldr.SymSize(s) + int64(align) - 1) &^ (int64(align) - 1)