From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Fri, 1 Oct 2021 23:19:27 +0000 (-0700)
Subject: cmd, runtime: mark assembly routines in FuncFlags
X-Git-Tag: go1.18beta1~1069
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=752cc07c77767d28a61525daa359d087b035f5c1;p=gostls13.git

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 <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
index 3d8d69f069..4fd2119b96 100644
--- 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
index 6beb4dd94c..348a16356e 100644
--- 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
index 68f6a26a76..084fcdf712 100644
--- 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
index d1fe1a4fcc..14591602a3 100644
--- 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.