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[dev.link] cmd/link: minor tweaks to PropagateLoaderChangesToSymbols

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Update PropagateLoaderChangesToSymbols so that it no longer requires
a sym.Symbols pointer. The intent is to generalize it a little to
allow it to be used in more than just linker Dwarf generation.

Change-Id: I9bddc5d39839eacd9113c945bb59d2873c0b088c
Reviewed-on: https://go-review.googlesource.com/c/go/+/224381
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
This commit is contained in:
Than McIntosh 2020-03-19 11:04:37 -04:00
parent 242b38c171
commit 3fa98a0436
2 changed files with 20 additions and 10 deletions
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3
src/cmd/link/internal/ld/dwarf.go
View File

@ -2048,7 +2048,8 @@ func (d *dwctxt2) dwarfGenerateDebugSyms() {
}
}
dwarfp2 = syms
dwarfp = d.ldr.PropagateLoaderChangesToSymbols(dwarfp2, d.linkctxt.Syms)
anonVerReplacement := d.linkctxt.Syms.IncVersion()
dwarfp = d.ldr.PropagateLoaderChangesToSymbols(dwarfp2, anonVerReplacement)
}
func (d *dwctxt2) collectlocs(syms []loader.Sym, units []*sym.CompilationUnit) []loader.Sym {

27
src/cmd/link/internal/loader/loader.go
View File

@ -254,6 +254,8 @@ type Loader struct {
strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
elfsetstring elfsetstringFunc
SymLookup func(name string, ver int) *sym.Symbol
}
const (
@ -1893,17 +1895,21 @@ func (l *Loader) PropagateSymbolChangesBackToLoader() {
// PropagateLoaderChangesToSymbols is a temporary shim function that
// takes a list of loader.Sym symbols and works to copy their contents
// and attributes over to a corresponding sym.Symbol. See the
// PropagateSymbolChangesBackToLoader header comment for more info.
// and attributes over to a corresponding sym.Symbol. The parameter
// anonVerReplacement specifies a version number for any new anonymous
// symbols encountered on the list, when creating sym.Symbols for them
// (or zero if we don't expect to encounter any new anon symbols). See
// the PropagateSymbolChangesBackToLoader header comment for more
// info.
//
// WARNING: this function is brittle and depends heavily on loader
// implementation. A key problem with doing this is that as things
// stand at the moment, some sym.Symbol contents/attributes are
// populated only when converting from loader.Sym to sym.Symbol
// in loadlibfull, meaning if we may wipe out some information
// when copying back.
// populated only when converting from loader.Sym to sym.Symbol in
// loadlibfull, meaning we may wipe out some information when copying
// back.
func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symbols) []*sym.Symbol {
func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, anonVerReplacement int) []*sym.Symbol {
result := []*sym.Symbol{}
relocfixup := []Sym{}
@ -1922,7 +1928,6 @@ func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symb
// sym.Symbols are created.
// First pass, symbol creation and symbol data fixup.
anonVerReplacement := syms.IncVersion()
rslice := []Reloc{}
for _, cand := range toconvert {
@ -1930,6 +1935,9 @@ func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symb
sv := l.SymVersion(cand)
st := l.SymType(cand)
if sv < 0 {
if anonVerReplacement == 0 {
panic("expected valid anon version replacement")
}
sv = anonVerReplacement
}
@ -1951,7 +1959,7 @@ func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symb
// or may not be in the name lookup map.
} else {
isnew = true
s = syms.Lookup(sn, sv)
s = l.SymLookup(sn, sv)
}
}
result = append(result, s)
@ -2046,7 +2054,7 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols, rp map[*sym.Symbol]*sym.Symbo
}
// Provide lookup functions for sym.Symbols.
syms.Lookup = func(name string, ver int) *sym.Symbol {
l.SymLookup = func(name string, ver int) *sym.Symbol {
i := l.LookupOrCreateSym(name, ver)
if s := l.Syms[i]; s != nil {
return s
@ -2056,6 +2064,7 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols, rp map[*sym.Symbol]*sym.Symbo
syms.Allsym = append(syms.Allsym, s) // XXX see above
return s
}
syms.Lookup = l.SymLookup
syms.ROLookup = func(name string, ver int) *sym.Symbol {
i := l.Lookup(name, ver)
return l.Syms[i]