[dev.link] cmd/link: fix loadpe to work with new obj file

Change-Id: I0fe88df182f13e7f04c8de0b82e111db441a26e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/204341
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

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

@@ -164,13 +164,6 @@ func (mode *LinkMode) String() string {
 	return fmt.Sprintf("LinkMode(%d)", uint8(*mode))
 }
 
-func canLinkHostObj(ctxt *Link) bool {
-	if !*flagNewobj {
-		return true
-	}
-	return ctxt.IsELF || objabi.GOOS == "darwin" || objabi.GOOS == "aix"
-}
-
 // mustLinkExternal reports whether the program being linked requires
 // the external linker be used to complete the link.
 func mustLinkExternal(ctxt *Link) (res bool, reason string) {
@@ -190,10 +183,6 @@ func mustLinkExternal(ctxt *Link) (res bool, reason string) {
 		return true, "msan"
 	}
 
-	if iscgo && !canLinkHostObj(ctxt) {
-		return true, "TODO: newobj"
-	}
-
 	// Internally linking cgo is incomplete on some architectures.
 	// https://golang.org/issue/14449
 	// https://golang.org/issue/21961

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

@@ -1705,8 +1705,9 @@ func ldobj(ctxt *Link, f *bio.Reader, lib *sym.Library, length int64, pn string,
 	}
 
 	if c1 == 0x4c && c2 == 0x01 || c1 == 0x64 && c2 == 0x86 {
+		if *flagNewobj {
 			ldpe := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
-			textp, rsrc, err := loadpe.Load(ctxt.Arch, ctxt.Syms, f, pkg, length, pn)
+				textp, rsrc, err := loadpe.Load(ctxt.loader, ctxt.Arch, ctxt.Syms, f, pkg, length, pn)
 				if err != nil {
 					Errorf(nil, "%v", err)
 					return
@@ -1717,6 +1718,20 @@ func ldobj(ctxt *Link, f *bio.Reader, lib *sym.Library, length int64, pn string,
 				ctxt.Textp = append(ctxt.Textp, textp...)
 			}
 			return ldhostobj(ldpe, ctxt.HeadType, f, pkg, length, pn, file)
+		} else {
+			ldpe := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
+				textp, rsrc, err := loadpe.LoadOld(ctxt.Arch, ctxt.Syms, f, pkg, length, pn)
+				if err != nil {
+					Errorf(nil, "%v", err)
+					return
+				}
+				if rsrc != nil {
+					setpersrc(ctxt, rsrc)
+				}
+				ctxt.Textp = append(ctxt.Textp, textp...)
+			}
+			return ldhostobj(ldpe, ctxt.HeadType, f, pkg, length, pn, file)
+		}
 	}
 
 	if c1 == 0x01 && (c2 == 0xD7 || c2 == 0xF7) {

src/cmd/link/internal/loadpe/ldpe.go

@@ -9,6 +9,7 @@ import (
 	"cmd/internal/bio"
 	"cmd/internal/objabi"
 	"cmd/internal/sys"
+	"cmd/link/internal/loader"
 	"cmd/link/internal/sym"
 	"debug/pe"
 	"encoding/binary"
@@ -144,12 +145,21 @@ func (f *peBiobuf) ReadAt(p []byte, off int64) (int, error) {
 	return n, nil
 }
 
-// Load loads the PE file pn from input.
+func Load(l *loader.Loader, arch *sys.Arch, syms *sym.Symbols, input *bio.Reader, pkg string, length int64, pn string) (textp []*sym.Symbol, rsrc *sym.Symbol, err error) {
+	lookup := func(name string, version int) *sym.Symbol {
+		return l.LookupOrCreate(name, version, syms)
+	}
+	return load(arch, lookup, syms.IncVersion(), input, pkg, length, pn)
+}
+
+func LoadOld(arch *sys.Arch, syms *sym.Symbols, input *bio.Reader, pkg string, length int64, pn string) (textp []*sym.Symbol, rsrc *sym.Symbol, err error) {
+	return load(arch, syms.Lookup, syms.IncVersion(), input, pkg, length, pn)
+}
+
+// load loads the PE file pn from input.
 // Symbols are written into syms, and a slice of the text symbols is returned.
 // If an .rsrc section is found, its symbol is returned as rsrc.
-func Load(arch *sys.Arch, syms *sym.Symbols, input *bio.Reader, pkg string, length int64, pn string) (textp []*sym.Symbol, rsrc *sym.Symbol, err error) {
+func load(arch *sys.Arch, lookup func(string, int) *sym.Symbol, localSymVersion int, input *bio.Reader, pkg string, length int64, pn string) (textp []*sym.Symbol, rsrc *sym.Symbol, err error) {
-	localSymVersion := syms.IncVersion()
-
 	sectsyms := make(map[*pe.Section]*sym.Symbol)
 	sectdata := make(map[*pe.Section][]byte)
 
@@ -181,7 +191,7 @@ func Load(arch *sys.Arch, syms *sym.Symbols, input *bio.Reader, pkg string, leng
 		}
 
 		name := fmt.Sprintf("%s(%s)", pkg, sect.Name)
-		s := syms.Lookup(name, localSymVersion)
+		s := lookup(name, localSymVersion)
 
 		switch sect.Characteristics & (IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE) {
 		case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ: //.rdata
@@ -239,7 +249,7 @@ func Load(arch *sys.Arch, syms *sym.Symbols, input *bio.Reader, pkg string, leng
 				return nil, nil, fmt.Errorf("relocation number %d symbol index idx=%d cannot be large then number of symbols %d", j, r.SymbolTableIndex, len(f.COFFSymbols))
 			}
 			pesym := &f.COFFSymbols[r.SymbolTableIndex]
-			gosym, err := readpesym(arch, syms, f, pesym, sectsyms, localSymVersion)
+			gosym, err := readpesym(arch, lookup, f, pesym, sectsyms, localSymVersion)
 			if err != nil {
 				return nil, nil, err
 			}
@@ -351,7 +361,7 @@ func Load(arch *sys.Arch, syms *sym.Symbols, input *bio.Reader, pkg string, leng
 			}
 		}
 
-		s, err := readpesym(arch, syms, f, pesym, sectsyms, localSymVersion)
+		s, err := readpesym(arch, lookup, f, pesym, sectsyms, localSymVersion)
 		if err != nil {
 			return nil, nil, err
 		}
@@ -435,7 +445,7 @@ func issect(s *pe.COFFSymbol) bool {
 	return s.StorageClass == IMAGE_SYM_CLASS_STATIC && s.Type == 0 && s.Name[0] == '.'
 }
 
-func readpesym(arch *sys.Arch, syms *sym.Symbols, f *pe.File, pesym *pe.COFFSymbol, sectsyms map[*pe.Section]*sym.Symbol, localSymVersion int) (*sym.Symbol, error) {
+func readpesym(arch *sys.Arch, lookup func(string, int) *sym.Symbol, f *pe.File, pesym *pe.COFFSymbol, sectsyms map[*pe.Section]*sym.Symbol, localSymVersion int) (*sym.Symbol, error) {
 	symname, err := pesym.FullName(f.StringTable)
 	if err != nil {
 		return nil, err
@@ -481,10 +491,10 @@ func readpesym(arch *sys.Arch, syms *sym.Symbols, f *pe.File, pesym *pe.COFFSymb
 	case IMAGE_SYM_DTYPE_FUNCTION, IMAGE_SYM_DTYPE_NULL:
 		switch pesym.StorageClass {
 		case IMAGE_SYM_CLASS_EXTERNAL: //global
-			s = syms.Lookup(name, 0)
+			s = lookup(name, 0)
 
 		case IMAGE_SYM_CLASS_NULL, IMAGE_SYM_CLASS_STATIC, IMAGE_SYM_CLASS_LABEL:
-			s = syms.Lookup(name, localSymVersion)
+			s = lookup(name, localSymVersion)
 			s.Attr |= sym.AttrDuplicateOK
 
 		default: