cmd/internal/{dwarf,obj}: stop substituting "" with pkgprefix

cmd/asm and cmd/compile now always create symbols with the appropriate
package prefixes, so cmd/internal/dwarf and cmd/internal/obj can stop
worrying about qualifying names itself.

Change-Id: I9aee5d759bf0d41a61722c777e7f66fce957e79e
Reviewed-on: https://go-review.googlesource.com/c/go/+/523338
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/internal/dwarf/dwarf.go

@@ -16,8 +16,6 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-
-	"cmd/internal/objabi"
 )
 
 // InfoPrefix is the prefix for all the symbols containing DWARF info entries.
@@ -86,7 +84,6 @@ type Range struct {
 // creating the DWARF subprogram DIE(s) for a function.
 type FnState struct {
 	Name          string
-	Importpath    string
 	Info          Sym
 	Filesym       Sym
 	Loc           Sym
@@ -1241,15 +1238,8 @@ func PutAbstractFunc(ctxt Context, s *FnState) error {
 	Uleb128put(ctxt, s.Absfn, int64(abbrev))
 
 	fullname := s.Name
-	if strings.HasPrefix(s.Name, "\"\".") {
-		// Generate a fully qualified name for the function in the
-		// abstract case. This is so as to avoid the need for the
-		// linker to process the DIE with patchDWARFName(); we can't
-		// allow the name attribute of an abstract subprogram DIE to
-		// be rewritten, since it would change the offsets of the
-		// child DIEs (which we're relying on in order for abstract
-		// origin references to work).
-		fullname = objabi.PathToPrefix(s.Importpath) + "." + s.Name[3:]
+	if strings.HasPrefix(s.Name, `"".`) {
+		return fmt.Errorf("unqualified symbol name: %v", s.Name)
 	}
 	putattr(ctxt, s.Absfn, abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(fullname)), fullname)
 
@@ -1436,10 +1426,9 @@ func PutDefaultFunc(ctxt Context, s *FnState, isWrapper bool) error {
 	}
 	Uleb128put(ctxt, s.Info, int64(abbrev))
 
-	// Expand '"".' to import path.
 	name := s.Name
-	if s.Importpath != "" {
-		name = strings.Replace(name, "\"\".", objabi.PathToPrefix(s.Importpath)+".", -1)
+	if strings.HasPrefix(name, `"".`) {
+		return fmt.Errorf("unqualified symbol name: %v", name)
 	}
 
 	putattr(ctxt, s.Info, DW_ABRV_FUNCTION, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name)

src/cmd/internal/obj/dwarf.go

@@ -367,7 +367,6 @@ func (ctxt *Link) populateDWARF(curfn interface{}, s *LSym) {
 	filesym := ctxt.fileSymbol(s)
 	fnstate := &dwarf.FnState{
 		Name:          s.Name,
-		Importpath:    myimportpath,
 		Info:          info,
 		Filesym:       filesym,
 		Loc:           loc,
@@ -441,7 +440,6 @@ func (ctxt *Link) DwarfAbstractFunc(curfn interface{}, s *LSym) {
 	dwctxt := dwCtxt{ctxt}
 	fnstate := dwarf.FnState{
 		Name:          s.Name,
-		Importpath:    ctxt.Pkgpath,
 		Info:          absfn,
 		Absfn:         absfn,
 		StartLine:     startLine,

src/cmd/internal/obj/objfile.go

@@ -292,8 +292,8 @@ func (w *writer) StringTable() {
 			// Don't include them if Flag_noRefName
 			return
 		}
-		if w.pkgpath != "" {
-			s.Name = strings.Replace(s.Name, "\"\".", w.pkgpath+".", -1)
+		if strings.HasPrefix(s.Name, `"".`) {
+			w.ctxt.Diag("unqualified symbol name: %v", s.Name)
 		}
 		w.AddString(s.Name)
 	})

src/cmd/internal/obj/plist.go

@@ -22,6 +22,10 @@ type Plist struct {
 type ProgAlloc func() *Prog
 
 func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc) {
+	if ctxt.Pkgpath == "" {
+		panic("Flushplist called without Pkgpath")
+	}
+
 	// Build list of symbols, and assign instructions to lists.
 	var curtext *LSym
 	var etext *Prog
@@ -98,7 +102,7 @@ func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc) {
 	if ctxt.IsAsm {
 		pkgPrefix := objabi.PathToPrefix(ctxt.Pkgpath) + "."
 		for _, s := range text {
-			if !strings.HasPrefix(s.Name, `"".`) && !strings.HasPrefix(s.Name, pkgPrefix) {
+			if !strings.HasPrefix(s.Name, pkgPrefix) {
 				continue
 			}
 			// The current args_stackmap generation in the compiler assumes
@@ -187,15 +191,16 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int, start src.XPos) {
 		ctxt.Diag("%s: symbol %s redeclared", ctxt.PosTable.Pos(start), s.Name)
 		return
 	}
+	if strings.HasPrefix(s.Name, `"".`) {
+		ctxt.Diag("%s: unqualified symbol name: %s", ctxt.PosTable.Pos(start), s.Name)
+	}
 
 	// startLine should be the same line number that would be displayed via
 	// pcln, etc for the declaration (i.e., relative line number, as
 	// adjusted by //line).
 	_, startLine := ctxt.getFileSymbolAndLine(start)
 
-	// TODO(mdempsky): Remove once cmd/asm stops writing "" symbols.
-	name := strings.Replace(s.Name, "\"\"", ctxt.Pkgpath, -1)
-	s.Func().FuncID = objabi.GetFuncID(name, flag&WRAPPER != 0 || flag&ABIWRAPPER != 0)
+	s.Func().FuncID = objabi.GetFuncID(s.Name, flag&WRAPPER != 0 || flag&ABIWRAPPER != 0)
 	s.Func().FuncFlag = ctxt.toFuncFlag(flag)
 	s.Func().StartLine = startLine
 	s.Set(AttrOnList, true)

src/cmd/internal/obj/sym.go

@@ -219,6 +219,10 @@ func (ctxt *Link) GCLocalsSym(data []byte) *LSym {
 // asm is set to true if this is called by the assembler (i.e. not the compiler),
 // in which case all the symbols are non-package (for now).
 func (ctxt *Link) NumberSyms() {
+	if ctxt.Pkgpath == "" {
+		panic("NumberSyms called without package path")
+	}
+
 	if ctxt.Headtype == objabi.Haix {
 		// Data must be in a reliable order for reproducible builds.
 		// The original entries are in a reliable order, but the TOC symbols
@@ -249,9 +253,7 @@ func (ctxt *Link) NumberSyms() {
 
 	var idx, hashedidx, hashed64idx, nonpkgidx int32
 	ctxt.traverseSyms(traverseDefs|traversePcdata, func(s *LSym) {
-		// if Pkgpath is unknown, cannot hash symbols with relocations, as it
-		// may reference named symbols whose names are not fully expanded.
-		if s.ContentAddressable() && (ctxt.Pkgpath != "" || len(s.R) == 0) {
+		if s.ContentAddressable() {
 			if s.Size <= 8 && len(s.R) == 0 && contentHashSection(s) == 0 {
 				// We can use short hash only for symbols without relocations.
 				// Don't use short hash for symbols that belong in a particular section