qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-26 23:11:24 -07:00
Code Releases Activity

[dev.link] cmd/link: skip symtab entries for selected file local symbols

Browse Source 
Don't emit symbol table entries for compiler-generated file-local
symbols (this category includes .stmp_* temporaries and *.stkobj
symbols). Note that user-written static symbols within assembler
sources will still be added to the symbol table. Apply the same test
when emitting DWARF for global variables.

Change-Id: I4db77a2750a0b575e051dfea895c4742cf6709a6
Reviewed-on: https://go-review.googlesource.com/c/go/+/240539
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Than McIntosh 2020-06-30 10:22:13 -04:00
parent 0434d40934
commit 8aa036e913
5 changed files with 31 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/internal/goobj2/objfile.go
View File

@ -241,6 +241,7 @@ const SymABIstatic = ^uint16(0)
const (
ObjFlagShared = 1 << iota // this object is built with -shared
ObjFlagNeedNameExpansion // the linker needs to expand `"".` to package path in symbol names
ObjFlagFromAssembly // object is from asm src, not go
)
// Sym.Flag
@ -742,3 +743,4 @@ func (r *Reader) Flags() uint32 {
func (r *Reader) Shared() bool { return r.Flags()&ObjFlagShared != 0 }
func (r *Reader) NeedNameExpansion() bool { return r.Flags()&ObjFlagNeedNameExpansion != 0 }
func (r *Reader) FromAssembly() bool { return r.Flags()&ObjFlagFromAssembly != 0 }

3
src/cmd/internal/obj/objfile2.go
View File

@ -41,6 +41,9 @@ func WriteObjFile(ctxt *Link, b *bio.Writer, pkgpath string) {
if pkgpath == "" {
flags |= goobj2.ObjFlagNeedNameExpansion
}
if ctxt.IsAsm {
flags |= goobj2.ObjFlagFromAssembly
}
h := goobj2.Header{
Magic: goobj2.Magic,
Fingerprint: ctxt.Fingerprint,

7
src/cmd/link/internal/ld/dwarf.go
View File

@ -1887,11 +1887,12 @@ func dwarfGenerateDebugInfo(ctxt *Link) {
if d.ldr.SymGoType(idx) == 0 {
continue
}
sn := d.ldr.SymName(idx)
if ctxt.LinkMode != LinkExternal && isStaticTemp(sn) {
// Skip file local symbols (this includes static tmps, stack
// object symbols, and local symbols in assembler src files).
if d.ldr.IsFileLocal(idx) {
continue
}
sn := d.ldr.SymName(idx)
if sn == "" {
// skip aux symbols
continue

19
src/cmd/link/internal/ld/symtab.go
View File

@ -196,7 +196,14 @@ func genelfsym(ctxt *Link, elfbind int) {
return false
}
// FIXME: avoid having to do name inspections here.
// NB: the restrictions below on file local symbols are a bit
// arbitrary -- if it turns out we need nameless static
// symbols they could be relaxed/removed.
sn := ldr.SymName(s)
if (sn == "" || sn[0] == '.') && ldr.IsFileLocal(s) {
panic(fmt.Sprintf("unexpected file local symbol %d %s<%d>\n",
s, sn, ldr.SymVersion(s)))
}
if (sn == "" || sn[0] == '.') && !ldr.IsFileLocal(s) {
return false
}
@ -499,15 +506,14 @@ func (ctxt *Link) symtab() []sym.SymKind {
nsym := loader.Sym(ldr.NSym())
symGroupType := make([]sym.SymKind, nsym)
for s := loader.Sym(1); s < nsym; s++ {
name := ldr.SymName(s)
if !ctxt.IsExternal() && isStaticTemp(name) {
if !ctxt.IsExternal() && ldr.IsFileLocal(s) && !ldr.IsFromAssembly(s) {
ldr.SetAttrNotInSymbolTable(s, true)
}
if !ldr.AttrReachable(s) || ldr.AttrSpecial(s) || (ldr.SymType(s) != sym.SRODATA && ldr.SymType(s) != sym.SGOFUNC) {
continue
}
name := ldr.SymName(s)
switch {
case strings.HasPrefix(name, "type."):
if !ctxt.DynlinkingGo() {
@ -768,10 +774,3 @@ func (ctxt *Link) symtab() []sym.SymKind {
}
return symGroupType
}
func isStaticTemp(name string) bool {
if i := strings.LastIndex(name, "/"); i >= 0 {
name = name[i:]
}
return strings.Contains(name, "..stmp_")
}

14
src/cmd/link/internal/loader/loader.go
View File

@ -683,7 +683,19 @@ func (l *Loader) SymVersion(i Sym) int {
return int(abiToVer(r.Sym(li).ABI(), r.version))
}
func (l *Loader) IsFileLocal(i Sym) bool { return l.SymVersion(i) >= sym.SymVerStatic }
func (l *Loader) IsFileLocal(i Sym) bool {
return l.SymVersion(i) >= sym.SymVerStatic
}
// IsFromAssembly returns true if this symbol is derived from an
// object file generated by the Go assembler.
func (l *Loader) IsFromAssembly(i Sym) bool {
if l.IsExternal(i) {
return false
}
r, _ := l.toLocal(i)
return r.FromAssembly()
}
// Returns the type of the i-th symbol.
func (l *Loader) SymType(i Sym) sym.SymKind {