[dev.link] cmd/link: stream external relocations on 386 ELF

Change-Id: I17ff3ac82c8ac313f3a3c8e8129800ec9c05b991
Reviewed-on: https://go-review.googlesource.com/c/go/+/243643
Reviewed-by: Jeremy Faller <jeremy@golang.org>

src/cmd/link/internal/ld/asmb.go

@@ -19,7 +19,7 @@ import (
 // This function handles the first part.
 func asmb(ctxt *Link) {
 	ctxt.loader.InitOutData()
-	if ctxt.IsExternal() && !(ctxt.IsAMD64() && ctxt.IsELF) {
+	if ctxt.IsExternal() && !ctxt.StreamExtRelocs() {
 		ctxt.loader.InitExtRelocs()
 	}
 

src/cmd/link/internal/ld/data.go

@@ -159,7 +159,7 @@ func (st *relocSymState) relocsym(s loader.Sym, P []byte) {
 	target := st.target
 	syms := st.syms
 	var extRelocs []loader.ExtReloc
-	if target.IsExternal() && !(target.IsAMD64() && target.IsELF) {
+	if target.IsExternal() && !target.StreamExtRelocs() {
 		// preallocate a slice conservatively assuming that all
 		// relocs will require an external reloc
 		extRelocs = st.preallocExtRelocSlice(relocs.Count())
@@ -592,14 +592,14 @@ func (st *relocSymState) relocsym(s loader.Sym, P []byte) {
 
 	addExtReloc:
 		if needExtReloc {
-			if target.IsAMD64() && target.IsELF {
+			if target.StreamExtRelocs() {
 				extraExtReloc++
 			} else {
 				extRelocs = append(extRelocs, rr)
 			}
 		}
 	}
-	if target.IsExternal() && target.IsAMD64() && target.IsELF {
+	if target.IsExternal() && target.StreamExtRelocs() {
 		// On AMD64 ELF, we'll stream out the external relocations in elfrelocsect
 		// and we only need the count here.
 		// TODO: just count, but not compute the external relocations. For now it

src/cmd/link/internal/ld/elf.go

@@ -1372,7 +1372,7 @@ func elfrelocsect(ctxt *Link, out *OutBuf, sect *sym.Section, syms []loader.Sym)
 			break
 		}
 
-		if ctxt.IsAMD64() {
+		if ctxt.StreamExtRelocs() {
 			// Compute external relocations on the go, and pass to Elfreloc1
 			// to stream out.
 			relocs := ldr.Relocs(s)

src/cmd/link/internal/ld/target.go

@@ -181,3 +181,8 @@ func (t *Target) mustSetHeadType() {
 func (t *Target) IsBigEndian() bool {
 	return t.Arch.ByteOrder == binary.BigEndian
 }
+
+// Temporary helper.
+func (t *Target) StreamExtRelocs() bool {
+	return t.IsELF && (t.IsAMD64() || t.Is386())
+}