From 0434d4093458d24db6af1e65fb257cee78512c25 Mon Sep 17 00:00:00 2001
From: Than McIntosh <thanm@google.com>
Date: Tue, 30 Jun 2020 07:55:16 -0400
Subject: [PATCH] [dev.link] cmd/compile: mark stmp and stkobj symbols as
 static

Mark compiler-generated ".stmp_%d" and "<fn>.stkobj" symbols as
AttrStatic, so as to tell the linker that they do not need to be
inserted into its name lookup tables.

Change-Id: I59ffd11659b2c54c2d0ad41275d05c3f919e3b88
Reviewed-on: https://go-review.googlesource.com/c/go/+/240497
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
---
 src/cmd/compile/internal/gc/obj.go   | 4 +---
 src/cmd/compile/internal/gc/sinit.go | 3 ++-
 src/cmd/internal/obj/plist.go        | 3 +++
 src/cmd/internal/obj/sym.go          | 5 +++++
 4 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/cmd/compile/internal/gc/obj.go b/src/cmd/compile/internal/gc/obj.go
index 01126dc048..4f511f9c7b 100644
--- a/src/cmd/compile/internal/gc/obj.go
+++ b/src/cmd/compile/internal/gc/obj.go
@@ -291,10 +291,8 @@ func addGCLocals() {
 		}
 		if x := s.Func.StackObjects; x != nil {
 			attr := int16(obj.RODATA)
-			if s.DuplicateOK() {
-				attr |= obj.DUPOK
-			}
 			ggloblsym(x, int32(len(x.P)), attr)
+			x.Set(obj.AttrStatic, true)
 		}
 		if x := s.Func.OpenCodedDeferInfo; x != nil {
 			ggloblsym(x, int32(len(x.P)), obj.RODATA|obj.DUPOK)
diff --git a/src/cmd/compile/internal/gc/sinit.go b/src/cmd/compile/internal/gc/sinit.go
index 3c7571819e..83274bf6a3 100644
--- a/src/cmd/compile/internal/gc/sinit.go
+++ b/src/cmd/compile/internal/gc/sinit.go
@@ -6,6 +6,7 @@ package gc
 
 import (
 	"cmd/compile/internal/types"
+	"cmd/internal/obj"
 	"fmt"
 )
 
@@ -360,7 +361,7 @@ var statuniqgen int // name generator for static temps
 // returned node for readonly nodes.
 func staticname(t *types.Type) *Node {
 	// Don't use lookupN; it interns the resulting string, but these are all unique.
-	n := newname(lookup(fmt.Sprintf(".stmp_%d", statuniqgen)))
+	n := newname(lookup(fmt.Sprintf("%s%d", obj.StaticNamePref, statuniqgen)))
 	statuniqgen++
 	addvar(n, t, PEXTERN)
 	return n
diff --git a/src/cmd/internal/obj/plist.go b/src/cmd/internal/obj/plist.go
index d4f9089a2e..b27e6c163d 100644
--- a/src/cmd/internal/obj/plist.go
+++ b/src/cmd/internal/obj/plist.go
@@ -170,6 +170,9 @@ func (ctxt *Link) Globl(s *LSym, size int64, flag int) {
 	} else if flag&TLSBSS != 0 {
 		s.Type = objabi.STLSBSS
 	}
+	if strings.HasPrefix(s.Name, "\"\"."+StaticNamePref) {
+		s.Set(AttrStatic, true)
+	}
 }
 
 // EmitEntryLiveness generates PCDATA Progs after p to switch to the
diff --git a/src/cmd/internal/obj/sym.go b/src/cmd/internal/obj/sym.go
index bfc405cffb..7f5d9ebeea 100644
--- a/src/cmd/internal/obj/sym.go
+++ b/src/cmd/internal/obj/sym.go
@@ -264,6 +264,11 @@ func isNonPkgSym(ctxt *Link, s *LSym) bool {
 	return false
 }
 
+// StaticNamePref is the prefix the front end applies to static temporary
+// variables. When turned into LSyms, these can be tagged as static so
+// as to avoid inserting them into the linker's name lookup tables.
+const StaticNamePref = ".stmp_"
+
 type traverseFlag uint32
 
 const (