[dev.link] cmd/link: stop populating lib/unit.Textp

lib.Textp was used for text address assignment and trampoline
insertion. Now that it has been converted to using the loader,
no need to populate lib.Textp.

Port the logic of canonicalizing dupok symbol's package to the
loader.

unit.Textp was used for DWARF generation, which has also been
converted to using the loader.

Change-Id: I22d4dd30a52a29dd5b1b7b795d43a19f6215e4ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/228140
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

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

@@ -413,7 +413,7 @@ func relocsym(target *Target, ldr *loader.Loader, err *ErrorReporter, syms *Arch
 		case objabi.R_ADDRCUOFF:
 			// debug_range and debug_loc elements use this relocation type to get an
 			// offset from the start of the compile unit.
-			o = Symaddr(r.Sym) + r.Add - Symaddr(r.Sym.Unit.Textp[0])
+			o = Symaddr(r.Sym) + r.Add - Symaddr(ldr.Syms[r.Sym.Unit.Textp2[0]])
 
 			// r->sym can be null when CALL $(constant) is transformed from absolute PC to relative PC call.
 		case objabi.R_GOTPCREL:

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

@@ -5,7 +5,6 @@
 package ld
 
 import (
-	"cmd/internal/objabi"
 	"cmd/link/internal/sym"
 )
 
@@ -46,11 +45,9 @@ func deadcode(ctxt *Link) {
 }
 
 // addToTextp populates the context Textp slice (needed in various places
-// in the linker) and also the unit Textp slices (needed by the "old"
+// in the linker).
-// phase 2 DWARF generation).
 func addToTextp(ctxt *Link) {
-
+	// Set up ctxt.Textp, based on ctxt.Textp2.
-	// First set up ctxt.Textp, based on ctxt.Textp2.
 	textp := make([]*sym.Symbol, 0, len(ctxt.Textp2))
 	haveshlibs := len(ctxt.Shlibs) > 0
 	for _, tsym := range ctxt.Textp2 {
@@ -64,37 +61,4 @@ func addToTextp(ctxt *Link) {
 		textp = append(textp, sp)
 	}
 	ctxt.Textp = textp
-
-	// Dupok symbols may be defined in multiple packages; the
-	// associated package for a dupok sym is chosen sort of
-	// arbitrarily (the first containing package that the linker
-	// loads). The loop below canonicalizes the File to the package
-	// with which it will be laid down in text. Assumes that
-	// ctxt.Library is already in postorder.
-	for _, doInternal := range [2]bool{true, false} {
-		for _, lib := range ctxt.Library {
-			if isRuntimeDepPkg(lib.Pkg) != doInternal {
-				continue
-			}
-			for _, dsym := range lib.DupTextSyms2 {
-				tsp := ctxt.loader.Syms[dsym]
-				if !tsp.Attr.OnList() {
-					tsp.Attr |= sym.AttrOnList
-					tsp.File = objabi.PathToPrefix(lib.Pkg)
-				}
-			}
-		}
-	}
-
-	// Finally, set up compilation unit Textp slices. Can be removed
-	// once loader-Sym DWARF-gen phase 2 is always enabled.
-	for _, lib := range ctxt.Library {
-		for _, unit := range lib.Units {
-			for _, usym := range unit.Textp2 {
-				usp := ctxt.loader.Syms[usym]
-				usp.Attr |= sym.AttrOnList
-				unit.Textp = append(unit.Textp, usp)
-			}
-		}
-	}
 }

src/cmd/link/internal/loader/loader.go

@@ -1252,10 +1252,10 @@ func (l *Loader) SymUnit(i Sym) *sym.CompilationUnit {
 // shared library), will hold the library name.
 // NOTE: this correspondes to sym.Symbol.File field.
 func (l *Loader) SymPkg(i Sym) string {
+	if f, ok := l.symPkg[i]; ok {
+		return f
+	}
 	if l.IsExternal(i) {
-		if f, ok := l.symPkg[i]; ok {
-			return f
-		}
 		pp := l.getPayload(i)
 		if pp.objidx != 0 {
 			r := l.objs[pp.objidx].r
@@ -1275,9 +1275,6 @@ func (l *Loader) SetSymPkg(i Sym, pkg string) {
 	if i >= Sym(len(l.objSyms)) || i == 0 {
 		panic("bad symbol index in SetSymPkg")
 	}
-	if !l.IsExternal(i) {
-		panic("can't set file for non-external sym")
-	}
 	l.symPkg[i] = pkg
 }
 
@@ -2452,7 +2449,6 @@ func (l *Loader) CreateStaticSym(name string) Sym {
 }
 
 func loadObjFull(l *Loader, r *oReader) {
-	lib := r.unit.Lib
 	resolveSymRef := func(s goobj2.SymRef) *sym.Symbol {
 		i := l.resolve(r, s)
 		return l.Syms[i]
@@ -2463,34 +2459,16 @@ func loadObjFull(l *Loader, r *oReader) {
 		// content will actually be provided by a different object
 		// (to which its global index points). Skip those symbols.
 		gi := l.toGlobal(r, i)
-		var isdup bool
 		if r2, i2 := l.toLocal(gi); r2 != r || i2 != i {
-			isdup = true
-		}
-
-		osym := r.Sym(i)
-		dupok := osym.Dupok()
-		if dupok && isdup {
-			if l.attrReachable.Has(gi) {
-				// A dupok symbol is resolved to another package. We still need
-				// to record its presence in the current package, as the trampoline
-				// pass expects packages are laid out in dependency order.
-				s := l.Syms[gi]
-				if s.Type == sym.STEXT {
-					lib.DupTextSyms = append(lib.DupTextSyms, s)
-				}
-			}
 			continue
 		}
-
-		if isdup {
-			continue // come from a different object
-		}
 		s := l.Syms[gi]
 		if s == nil {
 			continue
 		}
 
+		osym := r.Sym(i)
+		dupok := osym.Dupok()
 		local := osym.Local()
 		makeTypelink := osym.Typelink()
 		size := osym.Siz()
@@ -2711,7 +2689,7 @@ func (l *Loader) AssignTextSymbolOrder(libs []*sym.Library, intlibs []bool, exts
 			}
 			libtextp2 := []sym.LoaderSym{}
 			lists := [2][]sym.LoaderSym{lib.Textp2, lib.DupTextSyms2}
-			for _, list := range lists {
+			for i, list := range lists {
 				for _, s := range list {
 					sym := Sym(s)
 					if l.attrReachable.Has(sym) && !assignedToUnit.Has(sym) {
@@ -2722,6 +2700,14 @@ func (l *Loader) AssignTextSymbolOrder(libs []*sym.Library, intlibs []bool, exts
 							unit.Textp2 = append(unit.Textp2, s)
 							assignedToUnit.Set(sym)
 						}
+						// Dupok symbols may be defined in multiple packages; the
+						// associated package for a dupok sym is chosen sort of
+						// arbitrarily (the first containing package that the linker
+						// loads). Canonicalizes its Pkg to the package with which
+						// it will be laid down in text.
+						if i == 1 /* DupTextSyms2 */ && l.SymPkg(sym) != lib.Pkg {
+							l.SetSymPkg(sym, lib.Pkg)
+						}
 					}
 				}
 			}

src/cmd/link/internal/sym/library.go

@@ -13,8 +13,6 @@ type Library struct {
 	Hash          string
 	ImportStrings []string
 	Imports       []*Library
-	Textp         []*Symbol // text symbols defined in this library
-	DupTextSyms   []*Symbol // dupok text symbols defined in this library
 	Main          bool
 	Safe          bool
 	Units         []*CompilationUnit