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[dev.link] cmd/link: minor tweaks to PropagateLoaderChangesToSymbols
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 <[email protected]> Reviewed-by: Jeremy Faller <[email protected]>
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2 files changed

Lines changed: 20 additions & 10 deletions

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‎src/cmd/link/internal/ld/dwarf.go‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2048,7 +2048,8 @@ func (d *dwctxt2) dwarfGenerateDebugSyms() {
20482048
}
20492049
}
20502050
dwarfp2 = syms
2051-
dwarfp = d.ldr.PropagateLoaderChangesToSymbols(dwarfp2, d.linkctxt.Syms)
2051+
anonVerReplacement := d.linkctxt.Syms.IncVersion()
2052+
dwarfp = d.ldr.PropagateLoaderChangesToSymbols(dwarfp2, anonVerReplacement)
20522053
}
20532054

20542055
func (d *dwctxt2) collectlocs(syms []loader.Sym, units []*sym.CompilationUnit) []loader.Sym {

‎src/cmd/link/internal/loader/loader.go‎

Lines changed: 18 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -254,6 +254,8 @@ type Loader struct {
254254
strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
255255

256256
elfsetstring elfsetstringFunc
257+
258+
SymLookup func(name string, ver int) *sym.Symbol
257259
}
258260

259261
const (
@@ -1893,17 +1895,21 @@ func (l *Loader) PropagateSymbolChangesBackToLoader() {
18931895

18941896
// PropagateLoaderChangesToSymbols is a temporary shim function that
18951897
// takes a list of loader.Sym symbols and works to copy their contents
1896-
// and attributes over to a corresponding sym.Symbol. See the
1897-
// PropagateSymbolChangesBackToLoader header comment for more info.
1898+
// and attributes over to a corresponding sym.Symbol. The parameter
1899+
// anonVerReplacement specifies a version number for any new anonymous
1900+
// symbols encountered on the list, when creating sym.Symbols for them
1901+
// (or zero if we don't expect to encounter any new anon symbols). See
1902+
// the PropagateSymbolChangesBackToLoader header comment for more
1903+
// info.
18981904
//
18991905
// WARNING: this function is brittle and depends heavily on loader
19001906
// implementation. A key problem with doing this is that as things
19011907
// stand at the moment, some sym.Symbol contents/attributes are
1902-
// populated only when converting from loader.Sym to sym.Symbol
1903-
// in loadlibfull, meaning if we may wipe out some information
1904-
// when copying back.
1908+
// populated only when converting from loader.Sym to sym.Symbol in
1909+
// loadlibfull, meaning we may wipe out some information when copying
1910+
// back.
19051911

1906-
func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symbols) []*sym.Symbol {
1912+
func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, anonVerReplacement int) []*sym.Symbol {
19071913

19081914
result := []*sym.Symbol{}
19091915
relocfixup := []Sym{}
@@ -1922,14 +1928,16 @@ func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symb
19221928
// sym.Symbols are created.
19231929

19241930
// First pass, symbol creation and symbol data fixup.
1925-
anonVerReplacement := syms.IncVersion()
19261931
rslice := []Reloc{}
19271932
for _, cand := range toconvert {
19281933

19291934
sn := l.SymName(cand)
19301935
sv := l.SymVersion(cand)
19311936
st := l.SymType(cand)
19321937
if sv < 0 {
1938+
if anonVerReplacement == 0 {
1939+
panic("expected valid anon version replacement")
1940+
}
19331941
sv = anonVerReplacement
19341942
}
19351943

@@ -1951,7 +1959,7 @@ func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symb
19511959
// or may not be in the name lookup map.
19521960
} else {
19531961
isnew = true
1954-
s = syms.Lookup(sn, sv)
1962+
s = l.SymLookup(sn, sv)
19551963
}
19561964
}
19571965
result = append(result, s)
@@ -2046,7 +2054,7 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols, rp map[*sym.Symbol]*sym.Symbo
20462054
}
20472055

20482056
// Provide lookup functions for sym.Symbols.
2049-
syms.Lookup = func(name string, ver int) *sym.Symbol {
2057+
l.SymLookup = func(name string, ver int) *sym.Symbol {
20502058
i := l.LookupOrCreateSym(name, ver)
20512059
if s := l.Syms[i]; s != nil {
20522060
return s
@@ -2056,6 +2064,7 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols, rp map[*sym.Symbol]*sym.Symbo
20562064
syms.Allsym = append(syms.Allsym, s) // XXX see above
20572065
return s
20582066
}
2067+
syms.Lookup = l.SymLookup
20592068
syms.ROLookup = func(name string, ver int) *sym.Symbol {
20602069
i := l.Lookup(name, ver)
20612070
return l.Syms[i]

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