5 files changed, 32 insertions, 1 deletions
diff --git a/src/cmd/link/internal/ld/data.go b/src/cmd/link/internal/ld/data.go
index a730125cf2..0a3418bfc9 100644
--- a/src/cmd/link/internal/ld/data.go
+++ b/src/cmd/link/internal/ld/data.go
@@ -698,6 +698,9 @@ func windynrelocsym(ctxt *Link, rel *loader.SymbolBuilder, s loader.Sym) {
 	relocs := ctxt.loader.Relocs(s)
 	for ri := 0; ri < relocs.Count(); ri++ {
 		r := relocs.At(ri)
+		if r.IsMarker() {
+			continue // skip marker relocations
+		}
 		targ := r.Sym()
 		if targ == 0 {
 			continue
@@ -775,6 +778,9 @@ func dynrelocsym(ctxt *Link, s loader.Sym) {
 	relocs := ldr.Relocs(s)
 	for ri := 0; ri < relocs.Count(); ri++ {
 		r := relocs.At(ri)
+		if r.IsMarker() {
+			continue // skip marker relocations
+		}
 		if ctxt.BuildMode == BuildModePIE && ctxt.LinkMode == LinkInternal {
 			// It's expected that some relocations will be done
 			// later by relocsym (R_TLS_LE, R_ADDROFF), so
diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go
index 7f14aa3d27..816a23b9a7 100644
--- a/src/cmd/link/internal/ld/deadcode.go
+++ b/src/cmd/link/internal/ld/deadcode.go
@@ -153,6 +153,20 @@ func (d *deadcodePass) flood() {
 				// do nothing for now as we still load all type symbols.
 				continue
 			}
+			if t == objabi.R_USEIFACE {
+				// R_USEIFACE is a marker relocation that tells the linker the type is
+				// converted to an interface, i.e. should have UsedInIface set. See the
+				// comment below for why we need to unset the Reachable bit and re-mark it.
+				rs := r.Sym()
+				if !d.ldr.AttrUsedInIface(rs) {
+					d.ldr.SetAttrUsedInIface(rs, true)
+					if d.ldr.AttrReachable(rs) {
+						d.ldr.SetAttrReachable(rs, false)
+						d.mark(rs, symIdx)
+					}
+				}
+				continue
+			}
 			rs := r.Sym()
 			if isgotype && usedInIface && d.ldr.IsGoType(rs) && !d.ldr.AttrUsedInIface(rs) {
 				// If a type is converted to an interface, it is possible to obtain an
diff --git a/src/cmd/link/internal/ld/testdata/deadcode/ifacemethod.go b/src/cmd/link/internal/ld/testdata/deadcode/ifacemethod.go
index b62f18c342..32a24cf6f0 100644
--- a/src/cmd/link/internal/ld/testdata/deadcode/ifacemethod.go
+++ b/src/cmd/link/internal/ld/testdata/deadcode/ifacemethod.go
@@ -18,6 +18,13 @@ var p *T
 var e interface{}
 
 func main() {
-	p = new(T) // used T, but never converted to interface
+	p = new(T) // used T, but never converted to interface in any reachable code
 	e.(I).M()  // used I and I.M
 }
+
+func Unused() { // convert T to interface, but this function is not reachable
+	var i I = T(0)
+	i.M()
+}
+
+var Unused2 interface{} = T(1) // convert T to interface, in an unreachable global initializer
diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go
index 43a0352e0b..ea99233f67 100644
--- a/src/cmd/link/internal/loader/loader.go
+++ b/src/cmd/link/internal/loader/loader.go
@@ -63,6 +63,7 @@ type Reloc struct {
 func (rel Reloc) Type() objabi.RelocType { return objabi.RelocType(rel.Reloc.Type()) + rel.typ }
 func (rel Reloc) Sym() Sym               { return rel.l.resolve(rel.r, rel.Reloc.Sym()) }
 func (rel Reloc) SetSym(s Sym)           { rel.Reloc.SetSym(goobj.SymRef{PkgIdx: 0, SymIdx: uint32(s)}) }
+func (rel Reloc) IsMarker() bool         { return rel.Siz() == 0 }
 
 func (rel Reloc) SetType(t objabi.RelocType) {
 	if t != objabi.RelocType(uint8(t)) {
diff --git a/src/cmd/link/internal/wasm/asm.go b/src/cmd/link/internal/wasm/asm.go
index 3bd56a6e3a..31851fbb56 100644
--- a/src/cmd/link/internal/wasm/asm.go
+++ b/src/cmd/link/internal/wasm/asm.go
@@ -167,6 +167,9 @@ func asmb2(ctxt *ld.Link, ldr *loader.Loader) {
 			off := int32(0)
 			for ri := 0; ri < relocs.Count(); ri++ {
 				r := relocs.At(ri)
+				if r.Siz() == 0 {
+					continue // skip marker relocations
+				}
 				wfn.Write(P[off:r.Off()])
 				off = r.Off()
 				rs := ldr.ResolveABIAlias(r.Sym())