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[dev.link] cmd/link: begin converting dodata() to loader APIs

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This patch begins the work of converting the linker's dodata phase to
work with loader APIs. Passes all.bash on linux/amd64, but hasn't been
tested on anything else (more arch-specific code needs to be written).
Use of the new dodata() phase is currently gated by a temporary
command line flag ("-newdodata"), and there is code in the linker's
main routine to insure that we only use the new version for the right
GOOS/GOARCH (currently restricted to ELF + AMD64).

Change-Id: Ied3966677d2a450bc3e0990e0f519b3fceaab806
Reviewed-on: https://go-review.googlesource.com/c/go/+/229706
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 2020-04-21 18:37:43 -04:00
parent 3d1007d28e
commit 941de9760b
18 changed files with 2207 additions and 560 deletions
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50
src/cmd/link/internal/loader/loader.go
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@ -1268,6 +1268,17 @@ func (l *Loader) SetSymDynid(i Sym, val int32) {
}
}
// DynIdSyms returns the set of symbols for which dynID is set to an
// interesting (non-default) value. This is expected to be a fairly
// small set.
func (l *Loader) DynidSyms() []Sym {
sl := make([]Sym, 0, len(l.dynid))
for s := range l.dynid {
sl = append(sl, s)
}
return sl
}
// SymGoType returns the 'Gotype' property for a given symbol (set by
// the Go compiler for variable symbols). This version relies on
// reading aux symbols for the target sym -- it could be that a faster
@ -2255,6 +2266,30 @@ func (l *Loader) addNewSym(i Sym, name string, ver int, unit *sym.CompilationUni
return s
}
// TopLevelSym tests a symbol (by name and kind) to determine whether
// the symbol first class sym (participating in the link) or is an
// anonymous aux or sub-symbol containing some sub-part or payload of
// another symbol.
func (l *Loader) TopLevelSym(s Sym) bool {
return topLevelSym(l.RawSymName(s), l.SymType(s))
}
// topLevelSym tests a symbol name and kind to determine whether
// the symbol first class sym (participating in the link) or is an
// anonymous aux or sub-symbol containing some sub-part or payload of
// another symbol.
func topLevelSym(sname string, skind sym.SymKind) bool {
if sname != "" {
return true
}
switch skind {
case sym.SDWARFINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
return true
default:
return false
}
}
// loadObjSyms creates sym.Symbol objects for the live Syms in the
// object corresponding to object reader "r". Return value is the
// number of sym.Reloc entries required for all the new symbols.
@ -2268,16 +2303,11 @@ func loadObjSyms(l *Loader, syms *sym.Symbols, r *oReader) int {
osym := r.Sym(i)
name := strings.Replace(osym.Name(r.Reader), "\"\".", r.pkgprefix, -1)
t := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
// NB: for the test below, we can skip most anonymous symbols
// since they will never be turned into sym.Symbols (eg:
// funcdata). DWARF symbols are an exception however -- we
// want to include all reachable but nameless DWARF symbols.
if name == "" {
switch t {
case sym.SDWARFINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES:
default:
continue
}
// Skip non-dwarf anonymous symbols (e.g. funcdata),
// since they will never be turned into sym.Symbols.
if !topLevelSym(name, t) {
continue
}
ver := abiToVer(osym.ABI(), r.version)
if t == sym.SXREF {