cmd/internal/gc, cmd/internal/ld, cmd/internal/obj: teach compiler about local symbols
This lets us avoid loading string constants via the GOT and (together with
http://golang.org/cl/9102) results in the fannkuch benchmark having very similar
register usage with -dynlink as without.
Change-Id: Ic3892b399074982b76773c3e547cfbba5dabb6f9
Reviewed-on: https://go-review.googlesource.com/9103
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
diff --git a/src/cmd/internal/gc/gsubr.go b/src/cmd/internal/gc/gsubr.go
index 1f6b7d2..53b3f6c 100644
--- a/src/cmd/internal/gc/gsubr.go
+++ b/src/cmd/internal/gc/gsubr.go
@@ -218,11 +218,15 @@
}
}
-func ggloblsym(s *Sym, width int32, flags int8) {
+func ggloblsym(s *Sym, width int32, flags int16) {
p := Thearch.Gins(obj.AGLOBL, nil, nil)
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_EXTERN
p.From.Sym = Linksym(s)
+ if flags&obj.LOCAL != 0 {
+ p.From.Sym.Local = true
+ flags &= ^obj.LOCAL
+ }
p.To.Type = obj.TYPE_CONST
p.To.Offset = int64(width)
p.From3.Offset = int64(flags)
diff --git a/src/cmd/internal/gc/obj.go b/src/cmd/internal/gc/obj.go
index 5885eb5..891f554 100644
--- a/src/cmd/internal/gc/obj.go
+++ b/src/cmd/internal/gc/obj.go
@@ -245,7 +245,7 @@
off = duint8(sym, off, 0) // terminating NUL for runtime
off = (off + Widthptr - 1) &^ (Widthptr - 1) // round to pointer alignment
- ggloblsym(sym, int32(off), obj.DUPOK|obj.RODATA)
+ ggloblsym(sym, int32(off), obj.DUPOK|obj.RODATA|obj.LOCAL)
return sym
}
@@ -269,7 +269,7 @@
off = dsname(sym, off, s[n:n+m])
}
- ggloblsym(sym, int32(off), obj.NOPTR)
+ ggloblsym(sym, int32(off), obj.NOPTR|obj.LOCAL)
if nam.Op != ONAME {
Fatal("slicebytes %v", nam)
diff --git a/src/cmd/internal/gc/pgen.go b/src/cmd/internal/gc/pgen.go
index 5848f98a..1667a5c 100644
--- a/src/cmd/internal/gc/pgen.go
+++ b/src/cmd/internal/gc/pgen.go
@@ -161,7 +161,7 @@
}
}
- ggloblsym(sym, int32(off), obj.RODATA)
+ ggloblsym(sym, int32(off), obj.RODATA|obj.LOCAL)
}
// Sort the list of stack variables. Autos after anything else,
diff --git a/src/cmd/internal/gc/reflect.go b/src/cmd/internal/gc/reflect.go
index 47697be..824ed0b 100644
--- a/src/cmd/internal/gc/reflect.go
+++ b/src/cmd/internal/gc/reflect.go
@@ -814,7 +814,7 @@
for i := 0; i < 2*Widthptr; i++ {
duint8(sbits, i, gcmask[i])
}
- ggloblsym(sbits, 2*int32(Widthptr), obj.DUPOK|obj.RODATA)
+ ggloblsym(sbits, 2*int32(Widthptr), obj.DUPOK|obj.RODATA|obj.LOCAL)
}
ot = dsymptr(s, ot, sbits, 0)
@@ -1203,7 +1203,7 @@
}
ot = dextratype(s, ot, t, xt)
- ggloblsym(s, int32(ot), int8(dupok|obj.RODATA))
+ ggloblsym(s, int32(ot), int16(dupok|obj.RODATA))
// generate typelink.foo pointing at s = type.foo.
// The linker will leave a table of all the typelinks for
@@ -1229,7 +1229,7 @@
case TARRAY, TCHAN, TFUNC, TMAP:
slink := typelinksym(t)
dsymptr(slink, 0, s, 0)
- ggloblsym(slink, int32(Widthptr), int8(dupok|obj.RODATA))
+ ggloblsym(slink, int32(Widthptr), int16(dupok|obj.RODATA))
}
}
diff --git a/src/cmd/internal/ld/objfile.go b/src/cmd/internal/ld/objfile.go
index 1e45d72..41534c8 100644
--- a/src/cmd/internal/ld/objfile.go
+++ b/src/cmd/internal/ld/objfile.go
@@ -72,8 +72,12 @@
if v != 0 && v != 1 {
log.Fatalf("invalid symbol version %d", v)
}
- dupok := int(rdint(f))
- dupok &= 1
+ flags := int(rdint(f))
+ dupok := flags & 1
+ local := false
+ if flags&2 != 0 {
+ local = true
+ }
size := int(rdint(f))
typ := rdsym(ctxt, f, pkg)
var data []byte
@@ -125,6 +129,7 @@
if s.Size < int64(size) {
s.Size = int64(size)
}
+ s.Local = local
if typ != nil { // if bss sym defined multiple times, take type from any one def
s.Gotype = typ
}
diff --git a/src/cmd/internal/ld/symtab.go b/src/cmd/internal/ld/symtab.go
index 4d57d87..31baba0 100644
--- a/src/cmd/internal/ld/symtab.go
+++ b/src/cmd/internal/ld/symtab.go
@@ -373,15 +373,7 @@
// just defined above will be first.
// hide the specific symbols.
for s := Ctxt.Allsym; s != nil; s = s.Allsym {
- if !s.Reachable || s.Special != 0 {
- continue
- }
-
- if strings.Contains(s.Name, "..gostring.") || strings.Contains(s.Name, "..gobytes.") {
- s.Local = true
- }
-
- if s.Type != obj.SRODATA {
+ if !s.Reachable || s.Special != 0 || s.Type != obj.SRODATA {
continue
}
diff --git a/src/cmd/internal/obj/link.go b/src/cmd/internal/obj/link.go
index 33b2858..39f8941 100644
--- a/src/cmd/internal/obj/link.go
+++ b/src/cmd/internal/obj/link.go
@@ -273,6 +273,7 @@
A_ARCHSPECIFIC
)
+// An LSym is the sort of symbol that is written to an object file.
type LSym struct {
Name string
Type int16
@@ -283,18 +284,25 @@
Leaf uint8
Seenglobl uint8
Onlist uint8
- Args int32
- Locals int32
- Value int64
- Size int64
- Next *LSym
- Gotype *LSym
- Autom *Auto
- Text *Prog
- Etext *Prog
- Pcln *Pcln
- P []byte
- R []Reloc
+ // Local means make the symbol local even when compiling Go code to reference Go
+ // symbols in other shared libraries, as in this mode symbols are global by
+ // default. "local" here means in the sense of the dynamic linker, i.e. not
+ // visible outside of the module (shared library or executable) that contains its
+ // definition. (When not compiling to support Go shared libraries, all symbols are
+ // local in this sense unless there is a cgo_export_* directive).
+ Local bool
+ Args int32
+ Locals int32
+ Value int64
+ Size int64
+ Next *LSym
+ Gotype *LSym
+ Autom *Auto
+ Text *Prog
+ Etext *Prog
+ Pcln *Pcln
+ P []byte
+ R []Reloc
}
type Pcln struct {
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
index 62426a5..473a4bf 100644
--- a/src/cmd/internal/obj/objfile.go
+++ b/src/cmd/internal/obj/objfile.go
@@ -400,7 +400,11 @@
wrint(b, int64(s.Type))
wrstring(b, s.Name)
wrint(b, int64(s.Version))
- wrint(b, int64(s.Dupok))
+ flags := int64(s.Dupok)
+ if s.Local {
+ flags |= 2
+ }
+ wrint(b, flags)
wrint(b, s.Size)
wrsym(b, s.Gotype)
wrdata(b, s.P)
diff --git a/src/cmd/internal/obj/textflag.go b/src/cmd/internal/obj/textflag.go
index e0e641d..b5d27a6 100644
--- a/src/cmd/internal/obj/textflag.go
+++ b/src/cmd/internal/obj/textflag.go
@@ -30,4 +30,7 @@
// This function uses its incoming context register.
NEEDCTXT = 64
+
+ // When passed to ggloblsym, causes Local to be set to true on the LSym it creates.
+ LOCAL = 128
)
diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index d4c10e6..e70bdca 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -251,6 +251,7 @@
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_EXTERN
p.From.Sym = s
+ p.From.Sym.Local = true
p.From.Offset = 0
}
@@ -294,6 +295,7 @@
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_EXTERN
p.From.Sym = s
+ p.From.Sym.Local = true
p.From.Offset = 0
}
}
@@ -327,11 +329,11 @@
}
if ctxt.Flag_dynlink {
- if p.As == ALEAQ && p.From.Type == obj.TYPE_MEM && p.From.Name == obj.NAME_EXTERN {
+ if p.As == ALEAQ && p.From.Type == obj.TYPE_MEM && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local {
p.As = AMOVQ
p.From.Type = obj.TYPE_ADDR
}
- if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN {
+ if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local {
if p.As != AMOVQ {
ctxt.Diag("do not know how to handle TYPE_ADDR in %v with -dynlink", p)
}
@@ -356,12 +358,12 @@
ctxt.Diag("don't know how to handle %v with -dynlink", p)
}
var source *obj.Addr
- if p.From.Name == obj.NAME_EXTERN {
- if p.To.Name == obj.NAME_EXTERN {
+ if p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local {
+ if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local {
ctxt.Diag("cannot handle NAME_EXTERN on both sides in %v with -dynlink", p)
}
source = &p.From
- } else if p.To.Name == obj.NAME_EXTERN {
+ } else if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local {
source = &p.To
} else {
return
