cmd, runtime: mark assembly routines in FuncFlags

There's no good way to ascertain at runtime whether a function was implemented in assembly. The existing workaround doesn't play nicely with some upcoming linker changes. This change introduces an explicit marker for routines implemented in assembly. This change doesn't use the new bit anywhere, it only introduces it. Change-Id: I4051dc0afc15b260724a04b9d18aeeb94911bb29 Reviewed-on: https://go-review.googlesource.com/c/go/+/353671 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 4, 2021 · 752cc07 · 752cc07
1 parent 7ee4c16
commit 752cc07
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Showing 4 changed files with 12 additions and 2 deletions.
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
@@ -772,6 +772,9 @@ func (ctxt *Link) writeSymDebugNamed(s *LSym, name string) {
  if s.Func() != nil && s.Func().FuncFlag&objabi.FuncFlag_TOPFRAME != 0 {
  fmt.Fprintf(ctxt.Bso, "topframe ")
  }
+ if s.Func() != nil && s.Func().FuncFlag&objabi.FuncFlag_ASM != 0 {
+ fmt.Fprintf(ctxt.Bso, "asm ")
+ }
  fmt.Fprintf(ctxt.Bso, "size=%d", s.Size)
  if s.Type == objabi.STEXT {
  fn := s.Func()

diff --git a/src/cmd/internal/obj/plist.go b/src/cmd/internal/obj/plist.go
@@ -156,7 +156,7 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int) {
  }
  name := strings.Replace(s.Name, "\"\"", ctxt.Pkgpath, -1)
  s.Func().FuncID = objabi.GetFuncID(name, flag&WRAPPER != 0 || flag&ABIWRAPPER != 0)
- s.Func().FuncFlag = toFuncFlag(flag)
+ s.Func().FuncFlag = ctxt.toFuncFlag(flag)
  s.Set(AttrOnList, true)
  s.Set(AttrDuplicateOK, flag&DUPOK != 0)
  s.Set(AttrNoSplit, flag&NOSPLIT != 0)
@@ -172,11 +172,14 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int) {
  ctxt.dwarfSym(s)
 }
 
-func toFuncFlag(flag int) objabi.FuncFlag {
+func (ctxt *Link) toFuncFlag(flag int) objabi.FuncFlag {
  var out objabi.FuncFlag
  if flag&TOPFRAME != 0 {
  out |= objabi.FuncFlag_TOPFRAME
  }
+ if ctxt.IsAsm {
+ out |= objabi.FuncFlag_ASM
+ }
  return out
 }
 

diff --git a/src/cmd/internal/objabi/funcid.go b/src/cmd/internal/objabi/funcid.go
@@ -13,6 +13,7 @@ type FuncFlag uint8
 const (
  FuncFlag_TOPFRAME = 1 << iota
  FuncFlag_SPWRITE
+ FuncFlag_ASM
 )
 
 // A FuncID identifies particular functions that need to be treated

diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
@@ -383,6 +383,9 @@ const (
  // to be an incomplete unwinding of the stack. In certain contexts
  // (in particular garbage collector stack scans) that is a fatal error.
  funcFlag_SPWRITE
+
+ // ASM indicates that a function was implemented in assembly.
+ funcFlag_ASM
 )
 
 // pcHeader holds data used by the pclntab lookups.