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cmd/compile, cmd/link: stop generating unused go.string.hdr symbols.

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name       old s/op    new s/op    delta
LinkCmdGo   0.29 ± 5%   0.29 ± 8%  -2.60%   (p=0.000 n=97+98)

name       old MaxRSS  new MaxRSS  delta
LinkCmdGo   106k ± 4%   105k ± 3%  -1.00%  (p=0.000 n=100+99)

Change-Id: I75a1c3b24ea711a15a5d2eae026b70b97ee7bad4
Reviewed-on: https://go-review.googlesource.com/31030
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
This commit is contained in:
shaharko 2016-10-13 22:31:46 +03:00 committed by Shahar Kohanim
parent 0017438139
commit 80a034642e
7 changed files with 23 additions and 71 deletions
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53
src/cmd/compile/internal/gc/obj.go
View File

@ -280,18 +280,7 @@ func dbvec(s *Sym, off int, bv bvec) int {
return off
}
// stringConstantSyms holds the pair of symbols we create for a
// constant string.
type stringConstantSyms struct {
hdr *obj.LSym // string header
data *obj.LSym // actual string data
}
// stringConstants maps from the symbol name we use for the string
// contents to the pair of linker symbols for that string.
var stringConstants = make(map[string]stringConstantSyms, 100)
func stringsym(s string) (hdr, data *obj.LSym) {
func stringsym(s string) (data *obj.LSym) {
var symname string
if len(s) > 100 {
// Huge strings are hashed to avoid long names in object files.
@ -308,33 +297,15 @@ func stringsym(s string) (hdr, data *obj.LSym) {
const prefix = "go.string."
symdataname := prefix + symname
// All the strings have the same prefix, so ignore it for map
// purposes, but use a slice of the symbol name string to
// reduce long-term memory overhead.
key := symdataname[len(prefix):]
if syms, ok := stringConstants[key]; ok {
return syms.hdr, syms.data
}
symhdrname := "go.string.hdr." + symname
symhdr := obj.Linklookup(Ctxt, symhdrname, 0)
symdata := obj.Linklookup(Ctxt, symdataname, 0)
stringConstants[key] = stringConstantSyms{symhdr, symdata}
if !symdata.Seenglobl {
// string data
off := dsnameLSym(symdata, 0, s)
ggloblLSym(symdata, int32(off), obj.DUPOK|obj.RODATA|obj.LOCAL)
}
// string header
off := 0
off = dsymptrLSym(symhdr, off, symdata, 0)
off = duintxxLSym(symhdr, off, uint64(len(s)), Widthint)
ggloblLSym(symhdr, int32(off), obj.DUPOK|obj.RODATA|obj.LOCAL)
// string data
off = dsnameLSym(symdata, 0, s)
ggloblLSym(symdata, int32(off), obj.DUPOK|obj.RODATA|obj.LOCAL)
return symhdr, symdata
return symdata
}
var slicebytes_gen int
@ -357,14 +328,6 @@ func slicebytes(nam *Node, s string, len int) {
duintxx(nam.Sym, off, uint64(len), Widthint)
}
func datagostring(sval string, a *obj.Addr) {
symhdr, _ := stringsym(sval)
a.Type = obj.TYPE_MEM
a.Name = obj.NAME_EXTERN
a.Sym = symhdr
a.Offset = 0
}
func dsname(s *Sym, off int, t string) int {
return dsnameLSym(Linksym(s), off, t)
}
@ -465,7 +428,7 @@ func gdatacomplex(nam *Node, cval *Mpcplx) {
func gdatastring(nam *Node, sval string) {
s := Linksym(nam.Sym)
_, symdata := stringsym(sval)
symdata := stringsym(sval)
s.WriteAddr(Ctxt, nam.Xoffset, Widthptr, symdata, 0)
s.WriteInt(Ctxt, nam.Xoffset+int64(Widthptr), Widthint, int64(len(sval)))
}

2
src/cmd/compile/internal/gc/ssa.go
View File

@ -4525,7 +4525,7 @@ func (s *ssaExport) TypeBytePtr() ssa.Type { return ptrto(Types[TUINT8]) }
// is the data component of a global string constant containing s.
func (*ssaExport) StringData(s string) interface{} {
// TODO: is idealstring correct? It might not matter...
_, data := stringsym(s)
data := stringsym(s)
return &ssa.ExternSymbol{Typ: idealstring, Sym: data}
}

18
src/cmd/internal/obj/link.go
View File

@ -393,7 +393,6 @@ const (
STYPE
SSTRING
SGOSTRING
SGOSTRINGHDR
SGOFUNC
SGCBITS
SRODATA
@ -417,7 +416,6 @@ const (
STYPERELRO
SSTRINGRELRO
SGOSTRINGRELRO
SGOSTRINGHDRRELRO
SGOFUNCRELRO
SGCBITSRELRO
SRODATARELRO
@ -466,7 +464,6 @@ var ReadOnly = []SymKind{
STYPE,
SSTRING,
SGOSTRING,
SGOSTRINGHDR,
SGOFUNC,
SGCBITS,
SRODATA,
@ -476,14 +473,13 @@ var ReadOnly = []SymKind{
// RelROMap describes the transformation of read-only symbols to rel-ro
// symbols.
var RelROMap = map[SymKind]SymKind{
STYPE: STYPERELRO,
SSTRING: SSTRINGRELRO,
SGOSTRING: SGOSTRINGRELRO,
SGOSTRINGHDR: SGOSTRINGHDRRELRO,
SGOFUNC: SGOFUNCRELRO,
SGCBITS: SGCBITSRELRO,
SRODATA: SRODATARELRO,
SFUNCTAB: SFUNCTABRELRO,
STYPE: STYPERELRO,
SSTRING: SSTRINGRELRO,
SGOSTRING: SGOSTRINGRELRO,
SGOFUNC: SGOFUNCRELRO,
SGCBITS: SGCBITSRELRO,
SRODATA: SRODATARELRO,
SFUNCTAB: SFUNCTABRELRO,
}
type Reloc struct {

4
src/cmd/internal/obj/symkind_string.go
View File

@ -4,9 +4,9 @@ package obj
import "fmt"
const _SymKind_name = "SxxxSTEXTSELFRXSECTSTYPESSTRINGSGOSTRINGSGOSTRINGHDRSGOFUNCSGCBITSSRODATASFUNCTABSELFROSECTSMACHOPLTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOSTRINGHDRRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSTYPELINKSITABLINKSSYMTABSPCLNTABSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASINITARRSDATASBSSSNOPTRBSSSTLSBSSSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSFILESFILEPATHSCONSTSDYNIMPORTSHOSTOBJSDWARFSECTSDWARFINFO"
const _SymKind_name = "SxxxSTEXTSELFRXSECTSTYPESSTRINGSGOSTRINGSGOFUNCSGCBITSSRODATASFUNCTABSELFROSECTSMACHOPLTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSTYPELINKSITABLINKSSYMTABSPCLNTABSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASINITARRSDATASBSSSNOPTRBSSSTLSBSSSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSFILESFILEPATHSCONSTSDYNIMPORTSHOSTOBJSDWARFSECTSDWARFINFO"
var _SymKind_index = [...]uint16{0, 4, 9, 19, 24, 31, 40, 52, 59, 66, 73, 81, 91, 100, 110, 122, 136, 153, 165, 177, 189, 202, 211, 220, 227, 235, 243, 249, 258, 266, 273, 283, 291, 296, 300, 309, 316, 321, 333, 345, 362, 379, 384, 393, 399, 409, 417, 427, 437}
var _SymKind_index = [...]uint16{0, 4, 9, 19, 24, 31, 40, 47, 54, 61, 69, 79, 88, 98, 110, 124, 136, 148, 160, 173, 182, 191, 198, 206, 214, 220, 229, 237, 244, 254, 262, 267, 271, 280, 287, 292, 304, 316, 333, 350, 355, 364, 370, 380, 388, 398, 408}
func (i SymKind) String() string {
if i < 0 || i >= SymKind(len(_SymKind_index)-1) {

4
src/cmd/link/internal/ld/data.go
View File

@ -1135,7 +1135,7 @@ func symalign(s *Symbol) int32 {
} else if s.Align != 0 {
return min
}
if (strings.HasPrefix(s.Name, "go.string.") && !strings.HasPrefix(s.Name, "go.string.hdr.")) || strings.HasPrefix(s.Name, "type..namedata.") {
if strings.HasPrefix(s.Name, "go.string.") || strings.HasPrefix(s.Name, "type..namedata.") {
// String data is just bytes.
// If we align it, we waste a lot of space to padding.
return min
@ -1336,7 +1336,7 @@ func (ctxt *Link) dodata() {
for _, s := range data[symnro] {
isRelro := len(s.R) > 0
switch s.Type {
case obj.STYPE, obj.SGOSTRINGHDR, obj.STYPERELRO, obj.SGOSTRINGHDRRELRO, obj.SGOFUNCRELRO:
case obj.STYPE, obj.STYPERELRO, obj.SGOFUNCRELRO:
// Symbols are not sorted yet, so it is possible
// that an Outer symbol has been changed to a
// relro Type before it reaches here.

2
src/cmd/link/internal/ld/lib.go
View File

@ -1890,13 +1890,11 @@ func genasmsym(ctxt *Link, put func(*Link, *Symbol, string, SymbolType, int64, *
obj.STYPE,
obj.SSTRING,
obj.SGOSTRING,
obj.SGOSTRINGHDR,
obj.SGOFUNC,
obj.SGCBITS,
obj.STYPERELRO,
obj.SSTRINGRELRO,
obj.SGOSTRINGRELRO,
obj.SGOSTRINGHDRRELRO,
obj.SGOFUNCRELRO,
obj.SGCBITSRELRO,
obj.SRODATARELRO,

11
src/cmd/link/internal/ld/symtab.go
View File

@ -435,10 +435,9 @@ func (ctxt *Link) symtab() {
return s
}
var (
symgostring = groupSym("go.string.*", obj.SGOSTRING)
symgostringhdr = groupSym("go.string.hdr.*", obj.SGOSTRINGHDR)
symgofunc = groupSym("go.func.*", obj.SGOFUNC)
symgcbits = groupSym("runtime.gcbits.*", obj.SGCBITS)
symgostring = groupSym("go.string.*", obj.SGOSTRING)
symgofunc = groupSym("go.func.*", obj.SGOFUNC)
symgcbits = groupSym("runtime.gcbits.*", obj.SGCBITS)
)
var symgofuncrel *Symbol
@ -508,10 +507,6 @@ func (ctxt *Link) symtab() {
s.Type = obj.SGOSTRING
s.Attr |= AttrHidden
s.Outer = symgostring
if strings.HasPrefix(s.Name, "go.string.hdr.") {
s.Type = obj.SGOSTRINGHDR
s.Outer = symgostringhdr
}
case strings.HasPrefix(s.Name, "runtime.gcbits."):
s.Type = obj.SGCBITS