[dev.link] all: merge branch 'master' into dev.link

Bring in Than's fix of #35779.

The only merge conflict is cmd/link/internal/loadelf/ldelf.go,
with a modification-deletion conflict.

Change-Id: Id2fcfd2094a31120966a6ea9c462b4ec76646b10

1 files changed, 46 insertions, 4 deletions

diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go
index 4fa0d5ddce..48ff5aecc8 100644
--- a/src/cmd/link/internal/loader/loader.go
+++ b/src/cmd/link/internal/loader/loader.go
@@ -111,6 +111,8 @@ type Loader struct {
 
 	Syms []*sym.Symbol // indexed symbols. XXX we still make sym.Symbol for now.
 
+	anonVersion int // most recently assigned ext static sym pseudo-version
+
 	Reachable bitmap // bitmap of reachable symbols, indexed by global index
 
 	// Used to implement field tracking; created during deadcode if
@@ -347,7 +349,7 @@ func (l *Loader) resolve(r *oReader, s goobj2.SymRef) Sym {
 // This is more like Syms.ROLookup than Lookup -- it doesn't create
 // new symbol.
 func (l *Loader) Lookup(name string, ver int) Sym {
-	if ver >= sym.SymVerStatic {
+	if ver >= sym.SymVerStatic || ver < 0 {
 		return l.extStaticSyms[nameVer{name, ver}]
 	}
 	return l.symsByName[ver][name]
@@ -842,13 +844,24 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols) {
 		l.Syms[oldI] = nil
 	}
 
-	// For now, add all symbols to ctxt.Syms.
+	// Add symbols to the ctxt.Syms lookup table. This explicitly
+	// skips things created via loader.Create (marked with versions
+	// less than zero), since if we tried to add these we'd wind up
+	// with collisions. Along the way, update the version from the
+	// negative anon version to something larger than sym.SymVerStatic
+	// (needed so that sym.symbol.IsFileLocal() works properly).
+	anonVerReplacement := syms.IncVersion()
 	for _, s := range l.Syms {
-		if s != nil && s.Name != "" {
+		if s == nil {
+			continue
+		}
+		if s.Name != "" && s.Version >= 0 {
 			syms.Add(s)
 		}
+		if s.Version < 0 {
+			s.Version = int16(anonVerReplacement)
+		}
 	}
-
 }
 
 // addNewSym adds a new sym.Symbol to the i-th index in the list of symbols.
@@ -980,6 +993,35 @@ func (l *Loader) LookupOrCreate(name string, version int, syms *sym.Symbols) *sy
 	return s
 }
 
+// Create creates a symbol with the specified name, returning a
+// sym.Symbol object for it. This method is intended for static/hidden
+// symbols discovered while loading host objects. We can see more than
+// one instance of a given static symbol with the same name/version,
+// so we can't add them to the lookup tables "as is". Instead assign
+// them fictitious (unique) versions, starting at -1 and decreasing by
+// one for each newly created symbol, and record them in the
+// extStaticSyms hash.
+func (l *Loader) Create(name string, syms *sym.Symbols) *sym.Symbol {
+	i := l.max + 1
+	l.max++
+	if l.extStart == 0 {
+		l.extStart = i
+	}
+
+	// Assign a new unique negative version -- this is to mark the
+	// symbol so that it can be skipped when ExtractSymbols is adding
+	// ext syms to the sym.Symbols hash.
+	l.anonVersion--
+	ver := l.anonVersion
+	l.extSyms = append(l.extSyms, nameVer{name, ver})
+	l.growSyms(int(i))
+	s := syms.Newsym(name, ver)
+	l.Syms[i] = s
+	l.extStaticSyms[nameVer{name, ver}] = i
+
+	return s
+}
+
 func loadObjFull(l *Loader, r *oReader) {
 	lib := r.unit.Lib
 	istart := l.startIndex(r)