cmd/internal/gc: delete Strlit, Zconv

Strlit was just a poor excuse for a Go string.
Use a Go string.
In the one case where it was a string-or-nil (Type.Note), use a *string.

Zconv was a poor excuse for %q. Use %q.
The only important part about Zconv's implementation
was that the compiler and linker agreed on the quoting rules.
Now they both use %q instead of having two Zconvs.

This CL *does* change the generated object files, because the
quoted strings end up in symbol names.
For example the string "\r\n" used to be named go.string."\r\n"
and is now go.string."\x0d\n".

Change-Id: I5c0d38e1570ffc495f0db1a20273c9564104a7e8
Reviewed-on: https://go-review.googlesource.com/6519Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

src/cmd/5g/cgen.go

@@ -387,7 +387,7 @@ func cgen(n *gc.Node, res *gc.Node) {
 			var n1 gc.Node
 			regalloc(&n1, gc.Types[gc.Tptr], res)
 			p1 := gins(arm.AMOVW, nil, &n1)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			gmove(&n1, res)
 			regfree(&n1)
 			break
@@ -1075,7 +1075,7 @@ func agenr(n *gc.Node, a *gc.Node, res *gc.Node) {
 		if gc.Debug['B'] == 0 && !n.Bounded {
 			// check bounds
 			if gc.Isconst(nl, gc.CTSTR) {
-				gc.Nodconst(&n4, gc.Types[gc.TUINT32], int64(len(nl.Val.U.Sval.S)))
+				gc.Nodconst(&n4, gc.Types[gc.TUINT32], int64(len(nl.Val.U.Sval)))
 			} else if gc.Isslice(nl.Type) || nl.Type.Etype == gc.TSTRING {
 				n1 = n3
 				n1.Op = gc.OINDREG
@@ -1102,7 +1102,7 @@ func agenr(n *gc.Node, a *gc.Node, res *gc.Node) {
 		if gc.Isconst(nl, gc.CTSTR) {
 			regalloc(&n3, gc.Types[gc.Tptr], res)
 			p1 := gins(arm.AMOVW, nil, &n3)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			p1.From.Type = obj.TYPE_ADDR
 		} else if gc.Isslice(nl.Type) || nl.Type.Etype == gc.TSTRING {
 			n1 = n3

src/cmd/6g/cgen.go

@@ -8,8 +8,9 @@ import (
 	"cmd/internal/obj"
 	"cmd/internal/obj/x86"
 	"fmt"
+
+	"cmd/internal/gc"
 )
-import "cmd/internal/gc"
 
 /*
  * reg.c
@@ -374,7 +375,7 @@ func cgen(n *gc.Node, res *gc.Node) {
 			var n1 gc.Node
 			regalloc(&n1, gc.Types[gc.Tptr], res)
 			p1 := gins(x86.ALEAQ, nil, &n1)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			gmove(&n1, res)
 			regfree(&n1)
 			break
@@ -794,7 +795,7 @@ func agenr(n *gc.Node, a *gc.Node, res *gc.Node) {
 				t = gc.Types[gc.TUINT64]
 			}
 			if gc.Isconst(nl, gc.CTSTR) {
-				gc.Nodconst(&nlen, t, int64(len(nl.Val.U.Sval.S)))
+				gc.Nodconst(&nlen, t, int64(len(nl.Val.U.Sval)))
 			} else if gc.Isslice(nl.Type) || nl.Type.Etype == gc.TSTRING {
 				if gc.Is64(nr.Type) {
 					var n5 gc.Node
@@ -823,7 +824,7 @@ func agenr(n *gc.Node, a *gc.Node, res *gc.Node) {
 		if gc.Isconst(nl, gc.CTSTR) {
 			regalloc(&n3, gc.Types[gc.Tptr], res)
 			p1 := gins(x86.ALEAQ, nil, &n3)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			gins(x86.AADDQ, &n2, &n3)
 			goto indexdone
 		}

src/cmd/8g/cgen.go

@@ -332,7 +332,7 @@ func cgen(n *gc.Node, res *gc.Node) {
 			var n1 gc.Node
 			regalloc(&n1, gc.Types[gc.Tptr], res)
 			p1 := gins(i386.ALEAL, nil, &n1)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			gmove(&n1, res)
 			regfree(&n1)
 			break
@@ -726,7 +726,7 @@ func agen(n *gc.Node, res *gc.Node) {
 
 			var nlen gc.Node
 			if gc.Isconst(nl, gc.CTSTR) {
-				gc.Nodconst(&nlen, t, int64(len(nl.Val.U.Sval.S)))
+				gc.Nodconst(&nlen, t, int64(len(nl.Val.U.Sval)))
 			} else if gc.Isslice(nl.Type) || nl.Type.Etype == gc.TSTRING {
 				nlen = n3
 				nlen.Type = t
@@ -747,7 +747,7 @@ func agen(n *gc.Node, res *gc.Node) {
 		if gc.Isconst(nl, gc.CTSTR) {
 			regalloc(&n3, gc.Types[gc.Tptr], res)
 			p1 := gins(i386.ALEAL, nil, &n3)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			p1.From.Scale = 1
 			p1.From.Index = n2.Val.U.Reg
 			goto indexdone

src/cmd/9g/cgen.go

@@ -380,7 +380,7 @@ func cgen(n *gc.Node, res *gc.Node) {
 			var n1 gc.Node
 			regalloc(&n1, gc.Types[gc.Tptr], res)
 			p1 := gins(ppc64.AMOVD, nil, &n1)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			gmove(&n1, res)
 			regfree(&n1)
 			break
@@ -783,7 +783,7 @@ func agenr(n *gc.Node, a *gc.Node, res *gc.Node) {
 		if gc.Debug['B'] == 0 && !n.Bounded {
 			// check bounds
 			if gc.Isconst(nl, gc.CTSTR) {
-				gc.Nodconst(&n4, gc.Types[gc.TUINT64], int64(len(nl.Val.U.Sval.S)))
+				gc.Nodconst(&n4, gc.Types[gc.TUINT64], int64(len(nl.Val.U.Sval)))
 			} else if gc.Isslice(nl.Type) || nl.Type.Etype == gc.TSTRING {
 				n1 = n3
 				n1.Op = gc.OINDREG
@@ -817,7 +817,7 @@ func agenr(n *gc.Node, a *gc.Node, res *gc.Node) {
 		if gc.Isconst(nl, gc.CTSTR) {
 			regalloc(&n3, gc.Types[gc.Tptr], res)
 			p1 := gins(ppc64.AMOVD, nil, &n3)
-			gc.Datastring(nl.Val.U.Sval.S, &p1.From)
+			gc.Datastring(nl.Val.U.Sval, &p1.From)
 			p1.From.Type = obj.TYPE_ADDR
 		} else if gc.Isslice(nl.Type) || nl.Type.Etype == gc.TSTRING {
 			n1 = n3

src/cmd/internal/gc/closure.go

@@ -532,7 +532,7 @@ func makepartialcall(fn *Node, t0 *Type, meth *Node) *Node {
 	}
 	if spkg == nil {
 		if makepartialcall_gopkg == nil {
-			makepartialcall_gopkg = mkpkg(newstrlit("go"))
+			makepartialcall_gopkg = mkpkg("go")
 		}
 		spkg = makepartialcall_gopkg
 	}

src/cmd/internal/gc/const.go

@@ -4,7 +4,10 @@
 
 package gc
 
-import "cmd/internal/obj"
+import (
+	"cmd/internal/obj"
+	"strings"
+)
 
 /*
  * truncate float literal fv to 32-bit or 64-bit precision
@@ -432,11 +435,10 @@ func tostr(v Val) Val {
 		if Mpcmpfixfix(v.U.Xval, Minintval[TINT]) < 0 || Mpcmpfixfix(v.U.Xval, Maxintval[TINT]) > 0 {
 			Yyerror("overflow in int -> string")
 		}
-		rune_ := uint(Mpgetfix(v.U.Xval))
-		s := &Strlit{S: string(rune_)}
+		r := uint(Mpgetfix(v.U.Xval))
 		v = Val{}
 		v.Ctype = CTSTR
-		v.U.Sval = s
+		v.U.Sval = string(r)
 
 	case CTFLT:
 		Yyerror("no float -> string")
@@ -445,7 +447,7 @@ func tostr(v Val) Val {
 	case CTNIL:
 		v = Val{}
 		v.Ctype = CTSTR
-		v.U.Sval = new(Strlit)
+		v.U.Sval = ""
 	}
 
 	return v
@@ -526,16 +528,15 @@ func evconst(n *Node) {
 	case OADDSTR:
 		var nr *Node
 		var nl *Node
-		var str *Strlit
 		var l2 *NodeList
 		for l1 := n.List; l1 != nil; l1 = l1.Next {
 			if Isconst(l1.N, CTSTR) && l1.Next != nil && Isconst(l1.Next.N, CTSTR) {
 				// merge from l1 up to but not including l2
-				str = new(Strlit)
+				var strs []string
 				l2 = l1
 				for l2 != nil && Isconst(l2.N, CTSTR) {
 					nr = l2.N
-					str.S += nr.Val.U.Sval.S
+					strs = append(strs, nr.Val.U.Sval)
 					l2 = l2.Next
 				}
 
@@ -543,7 +544,7 @@ func evconst(n *Node) {
 				*nl = *l1.N
 				nl.Orig = nl
 				nl.Val.Ctype = CTSTR
-				nl.Val.U.Sval = str
+				nl.Val.U.Sval = strings.Join(strs, "")
 				l1.N = nl
 				l1.Next = l2
 			}
@@ -1334,7 +1335,7 @@ func defaultlit2(lp **Node, rp **Node, force int) {
 }
 
 func cmpslit(l, r *Node) int {
-	return stringsCompare(l.Val.U.Sval.S, r.Val.U.Sval.S)
+	return stringsCompare(l.Val.U.Sval, r.Val.U.Sval)
 }
 
 func Smallintconst(n *Node) bool {

src/cmd/internal/gc/dcl.go

@@ -132,14 +132,14 @@ func testdclstack() {
 
 func redeclare(s *Sym, where string) {
 	if s.Lastlineno == 0 {
-		var tmp *Strlit
+		var tmp string
 		if s.Origpkg != nil {
 			tmp = s.Origpkg.Path
 		} else {
 			tmp = s.Pkg.Path
 		}
 		pkgstr := tmp
-		Yyerror("%v redeclared %s\n"+"\tprevious declaration during import \"%v\"", Sconv(s, 0), where, Zconv(pkgstr, 0))
+		Yyerror("%v redeclared %s\n"+"\tprevious declaration during import %q", Sconv(s, 0), where, pkgstr)
 	} else {
 		line1 := parserline()
 		line2 := int(s.Lastlineno)
@@ -823,7 +823,8 @@ func structfield(n *Node) *Type {
 
 	switch n.Val.Ctype {
 	case CTSTR:
-		f.Note = n.Val.U.Sval
+		f.Note = new(string)
+		*f.Note = n.Val.U.Sval
 
 	default:
 		Yyerror("field annotation must be string")
@@ -1284,7 +1285,7 @@ func methodsym(nsym *Sym, t0 *Type, iface int) *Sym {
 
 	if spkg == nil {
 		if methodsym_toppkg == nil {
-			methodsym_toppkg = mkpkg(newstrlit("go"))
+			methodsym_toppkg = mkpkg("go")
 		}
 		spkg = methodsym_toppkg
 	}

src/cmd/internal/gc/esc.go

@@ -217,9 +217,9 @@ type EscState struct {
 	recursive bool
 }
 
-var tags [16]*Strlit
+var tags [16]*string
 
-func mktag(mask int) *Strlit {
+func mktag(mask int) *string {
 	switch mask & EscMask {
 	case EscNone,
 		EscReturn:
@@ -235,22 +235,18 @@ func mktag(mask int) *Strlit {
 		return tags[mask]
 	}
 
-	buf := fmt.Sprintf("esc:0x%x", mask)
-	s := newstrlit(buf)
+	s := fmt.Sprintf("esc:0x%x", mask)
 	if mask < len(tags) {
-		tags[mask] = s
+		tags[mask] = &s
 	}
-	return s
+	return &s
 }
 
-func parsetag(note *Strlit) int {
-	if note == nil {
+func parsetag(note *string) int {
+	if note == nil || !strings.HasPrefix(*note, "esc:") {
 		return EscUnknown
 	}
-	if !strings.HasPrefix(note.S, "esc:") {
-		return EscUnknown
-	}
-	em := atoi(note.S[4:])
+	em := atoi((*note)[4:])
 	if em == 0 {
 		return EscNone
 	}
@@ -941,7 +937,7 @@ func escassign(e *EscState, dst *Node, src *Node) {
 	lineno = int32(lno)
 }
 
-func escassignfromtag(e *EscState, note *Strlit, dsts *NodeList, src *Node) int {
+func escassignfromtag(e *EscState, note *string, dsts *NodeList, src *Node) int {
 	var em int
 
 	em = parsetag(note)
@@ -969,7 +965,7 @@ func escassignfromtag(e *EscState, note *Strlit, dsts *NodeList, src *Node) int
 	}
 
 	if em != 0 && dsts == nil {
-		Fatal("corrupt esc tag %v or messed up escretval list\n", Zconv(note, 0))
+		Fatal("corrupt esc tag %q or messed up escretval list\n", note)
 	}
 	return em0
 }

src/cmd/internal/gc/export.go

@@ -87,7 +87,7 @@ func dumppkg(p *Pkg) {
 	if p.Direct == 0 {
 		suffix = " // indirect"
 	}
-	fmt.Fprintf(bout, "\timport %s \"%v\"%s\n", p.Name, Zconv(p.Path, 0), suffix)
+	fmt.Fprintf(bout, "\timport %s %q%s\n", p.Name, p.Path, suffix)
 }
 
 // Look for anything we need for the inline body
@@ -399,7 +399,7 @@ func dumpexport() {
  */
 func importsym(s *Sym, op int) *Sym {
 	if s.Def != nil && int(s.Def.Op) != op {
-		pkgstr := fmt.Sprintf("during import \"%v\"", Zconv(importpkg.Path, 0))
+		pkgstr := fmt.Sprintf("during import %q", importpkg.Path)
 		redeclare(s, pkgstr)
 	}
 
@@ -432,24 +432,24 @@ func pkgtype(s *Sym) *Type {
 	return s.Def.Type
 }
 
-func importimport(s *Sym, z *Strlit) {
+func importimport(s *Sym, path string) {
 	// Informational: record package name
 	// associated with import path, for use in
 	// human-readable messages.
 
-	if isbadimport(z) {
+	if isbadimport(path) {
 		errorexit()
 	}
-	p := mkpkg(z)
+	p := mkpkg(path)
 	if p.Name == "" {
 		p.Name = s.Name
 		Pkglookup(s.Name, nil).Npkg++
 	} else if p.Name != s.Name {
-		Yyerror("conflicting names %s and %s for package \"%v\"", p.Name, s.Name, Zconv(p.Path, 0))
+		Yyerror("conflicting names %s and %s for package %q", p.Name, s.Name, p.Path)
 	}
 
-	if incannedimport == 0 && myimportpath != "" && z.S == myimportpath {
-		Yyerror("import \"%v\": package depends on \"%v\" (import cycle)", Zconv(importpkg.Path, 0), Zconv(z, 0))
+	if incannedimport == 0 && myimportpath != "" && path == myimportpath {
+		Yyerror("import %q: package depends on %q (import cycle)", importpkg.Path, path)
 		errorexit()
 	}
 }
@@ -488,7 +488,7 @@ func importvar(s *Sym, t *Type) {
 		if Eqtype(t, s.Def.Type) {
 			return
 		}
-		Yyerror("inconsistent definition for var %v during import\n\t%v (in \"%v\")\n\t%v (in \"%v\")", Sconv(s, 0), Tconv(s.Def.Type, 0), Zconv(s.Importdef.Path, 0), Tconv(t, 0), Zconv(importpkg.Path, 0))
+		Yyerror("inconsistent definition for var %v during import\n\t%v (in %q)\n\t%v (in %q)", Sconv(s, 0), Tconv(s.Def.Type, 0), s.Importdef.Path, Tconv(t, 0), importpkg.Path)
 	}
 
 	n := newname(s)
@@ -518,7 +518,7 @@ func importtype(pt *Type, t *Type) {
 		declare(n, PEXTERN)
 		checkwidth(pt)
 	} else if !Eqtype(pt.Orig, t) {
-		Yyerror("inconsistent definition for type %v during import\n\t%v (in \"%v\")\n\t%v (in \"%v\")", Sconv(pt.Sym, 0), Tconv(pt, obj.FmtLong), Zconv(pt.Sym.Importdef.Path, 0), Tconv(t, obj.FmtLong), Zconv(importpkg.Path, 0))
+		Yyerror("inconsistent definition for type %v during import\n\t%v (in %q)\n\t%v (in %q)", Sconv(pt.Sym, 0), Tconv(pt, obj.FmtLong), pt.Sym.Importdef.Path, Tconv(t, obj.FmtLong), importpkg.Path)
 	}
 
 	if Debug['E'] != 0 {

src/cmd/internal/gc/fmt.go

@@ -45,8 +45,6 @@ import (
 //		Flags: those of %N
 //			','  separate items with ',' instead of ';'
 //
-//	%Z Strlit*	String literals
-//
 //   In mparith1.c:
 //      %B Mpint*	Big integers
 //	%F Mpflt*	Big floats
@@ -350,7 +348,7 @@ func Vconv(v *Val, flag int) string {
 
 	case CTSTR:
 		var fp string
-		fp += fmt.Sprintf("\"%v\"", Zconv(v.U.Sval, 0))
+		fp += fmt.Sprintf("%q", v.U.Sval)
 		return fp
 
 	case CTBOOL:
@@ -370,54 +368,6 @@ func Vconv(v *Val, flag int) string {
 	return fmt.Sprintf("<ctype=%d>", v.Ctype)
 }
 
-// Fmt "%Z": escaped string literals
-func Zconv(sp *Strlit, flag int) string {
-	if sp == nil {
-		return "<nil>"
-	}
-
-	// NOTE: Keep in sync with ../ld/go.c:/^Zconv.
-	s := sp.S
-	var n int
-	var fp string
-	for i := 0; i < len(s); i += n {
-		var r rune
-		r, n = utf8.DecodeRuneInString(s[i:])
-		switch r {
-		case utf8.RuneError:
-			if n == 1 {
-				fp += fmt.Sprintf("\\x%02x", s[i])
-				break
-			}
-			fallthrough
-
-			// fall through
-		default:
-			if r < ' ' {
-				fp += fmt.Sprintf("\\x%02x", r)
-				break
-			}
-
-			fp += string(r)
-
-		case '\t':
-			fp += "\\t"
-
-		case '\n':
-			fp += "\\n"
-
-		case '"',
-			'\\':
-			fp += `\` + string(r)
-
-		case 0xFEFF: // BOM, basically disallowed in source code
-			fp += "\\uFEFF"
-		}
-	}
-
-	return fp
-}
-
 /*
 s%,%,\n%g
 s%\n+%\n%g
@@ -477,7 +427,7 @@ func symfmt(s *Sym, flag int) string {
 
 			// If the name was used by multiple packages, display the full path,
 			if s.Pkg.Name != "" && Pkglookup(s.Pkg.Name, nil).Npkg > 1 {
-				return fmt.Sprintf("\"%v\".%s", Zconv(s.Pkg.Path, 0), s.Name)
+				return fmt.Sprintf("%q.%s", s.Pkg.Path, s.Name)
 			}
 			var fp string
 			fp += fmt.Sprintf("%s.%s", s.Pkg.Name, s.Name)
@@ -501,7 +451,7 @@ func symfmt(s *Sym, flag int) string {
 				Fatal("exporting synthetic symbol %s", s.Name)
 			}
 			if s.Pkg != builtinpkg {
-				return fmt.Sprintf("@\"%v\".%s", Zconv(s.Pkg.Path, 0), s.Name)
+				return fmt.Sprintf("@%q.%s", s.Pkg.Path, s.Name)
 			}
 		}
 	}
@@ -516,7 +466,7 @@ func symfmt(s *Sym, flag int) string {
 
 		// exportname needs to see the name without the prefix too.
 		if (fmtmode == FExp && !exportname(p)) || fmtmode == FDbg {
-			return fmt.Sprintf("@\"%v\".%s", Zconv(s.Pkg.Path, 0), p)
+			return fmt.Sprintf("@%q.%s", s.Pkg.Path, p)
 		}
 
 		return p
@@ -791,8 +741,8 @@ func typefmt(t *Type, flag int) string {
 				//if(t->funarg)
 				//	fmtstrcpy(fp, "_ ");
 				//else
-				if t.Embedded != 0 && s.Pkg != nil && len(s.Pkg.Path.S) > 0 {
-					fp += fmt.Sprintf("@\"%v\".? ", Zconv(s.Pkg.Path, 0))
+				if t.Embedded != 0 && s.Pkg != nil && len(s.Pkg.Path) > 0 {
+					fp += fmt.Sprintf("@%q.? ", s.Pkg.Path)
 				} else {
 					fp += "? "
 				}
@@ -806,7 +756,7 @@ func typefmt(t *Type, flag int) string {
 		}
 
 		if flag&obj.FmtShort == 0 /*untyped*/ && t.Note != nil {
-			fp += fmt.Sprintf(" \"%v\"", Zconv(t.Note, 0))
+			fp += fmt.Sprintf(" %q", *t.Note)
 		}
 		return fp
 

src/cmd/internal/gc/go.go

@@ -55,15 +55,6 @@ const (
 	MaxStackVarSize = 10 * 1024 * 1024
 )
 
-/*
- * note this is the representation
- * of the compilers string literals,
- * it is not the runtime representation
- */
-type Strlit struct {
-	S string
-}
-
 const (
 	Mpscale = 29
 	Mpprec  = 16
@@ -98,7 +89,7 @@ type Val struct {
 		Xval *Mpint
 		Fval *Mpflt
 		Cval *Mpcplx
-		Sval *Strlit
+		Sval string
 	}
 }
 
@@ -116,7 +107,7 @@ type Bvec struct {
 
 type Pkg struct {
 	Name     string
-	Path     *Strlit
+	Path     string
 	Pathsym  *Sym
 	Prefix   string
 	Link     *Pkg
@@ -279,7 +270,7 @@ type Type struct {
 	Width       int64
 	Down        *Type
 	Outer       *Type
-	Note        *Strlit
+	Note        *string
 	Bound       int64
 	Bucket      *Type
 	Hmap        *Type

src/cmd/internal/gc/go.y

@@ -251,13 +251,13 @@ import_package:
 			importpkg.Name = $2.Name;
 			Pkglookup($2.Name, nil).Npkg++;
 		} else if importpkg.Name != $2.Name {
-			Yyerror("conflicting names %s and %s for package \"%v\"", importpkg.Name, $2.Name, Zconv(importpkg.Path, 0));
+			Yyerror("conflicting names %s and %s for package %q", importpkg.Name, $2.Name, importpkg.Path);
 		}
 		importpkg.Direct = 1;
 		importpkg.Safe = curio.importsafe
 
 		if safemode != 0 && !curio.importsafe {
-			Yyerror("cannot import unsafe package \"%v\"", Zconv(importpkg.Path, 0));
+			Yyerror("cannot import unsafe package %q", importpkg.Path);
 		}
 	}
 
@@ -1130,7 +1130,7 @@ hidden_importsym:
 	{
 		var p *Pkg
 
-		if $2.U.Sval.S == "" {
+		if $2.U.Sval == "" {
 			p = importpkg;
 		} else {
 			if isbadimport($2.U.Sval) {
@@ -1144,7 +1144,7 @@ hidden_importsym:
 	{
 		var p *Pkg
 
-		if $2.U.Sval.S == "" {
+		if $2.U.Sval == "" {
 			p = importpkg;
 		} else {
 			if isbadimport($2.U.Sval) {
@@ -1975,7 +1975,7 @@ hidden_import:
 		importlist = list(importlist, $2);
 
 		if Debug['E'] > 0 {
-			print("import [%v] func %lN \n", Zconv(importpkg.Path, 0), $2);
+			print("import [%q] func %lN \n", importpkg.Path, $2);
 			if Debug['m'] > 2 && $2.Inl != nil {
 				print("inl body:%+H\n", $2.Inl);
 			}

src/cmd/internal/gc/lex.go

@@ -121,50 +121,50 @@ func Main() {
 	Ctxt.Bso = &bstdout
 	bstdout = *obj.Binitw(os.Stdout)
 
-	localpkg = mkpkg(newstrlit(""))
+	localpkg = mkpkg("")
 	localpkg.Prefix = "\"\""
 
 	// pseudo-package, for scoping
-	builtinpkg = mkpkg(newstrlit("go.builtin"))
+	builtinpkg = mkpkg("go.builtin")
 
 	builtinpkg.Prefix = "go.builtin" // not go%2ebuiltin
 
 	// pseudo-package, accessed by import "unsafe"
-	unsafepkg = mkpkg(newstrlit("unsafe"))
+	unsafepkg = mkpkg("unsafe")
 
 	unsafepkg.Name = "unsafe"
 
 	// real package, referred to by generated runtime calls
-	Runtimepkg = mkpkg(newstrlit("runtime"))
+	Runtimepkg = mkpkg("runtime")
 
 	Runtimepkg.Name = "runtime"
 
 	// pseudo-packages used in symbol tables
-	gostringpkg = mkpkg(newstrlit("go.string"))
+	gostringpkg = mkpkg("go.string")
 
 	gostringpkg.Name = "go.string"
 	gostringpkg.Prefix = "go.string" // not go%2estring
 
-	itabpkg = mkpkg(newstrlit("go.itab"))
+	itabpkg = mkpkg("go.itab")
 
 	itabpkg.Name = "go.itab"
 	itabpkg.Prefix = "go.itab" // not go%2eitab
 
-	weaktypepkg = mkpkg(newstrlit("go.weak.type"))
+	weaktypepkg = mkpkg("go.weak.type")
 
 	weaktypepkg.Name = "go.weak.type"
 	weaktypepkg.Prefix = "go.weak.type" // not go%2eweak%2etype
 
-	typelinkpkg = mkpkg(newstrlit("go.typelink"))
+	typelinkpkg = mkpkg("go.typelink")
 	typelinkpkg.Name = "go.typelink"
 	typelinkpkg.Prefix = "go.typelink" // not go%2etypelink
 
-	trackpkg = mkpkg(newstrlit("go.track"))
+	trackpkg = mkpkg("go.track")
 
 	trackpkg.Name = "go.track"
 	trackpkg.Prefix = "go.track" // not go%2etrack
 
-	typepkg = mkpkg(newstrlit("type"))
+	typepkg = mkpkg("type")
 
 	typepkg.Name = "type"
 
@@ -238,7 +238,7 @@ func Main() {
 	startProfile()
 
 	if flag_race != 0 {
-		racepkg = mkpkg(newstrlit("runtime/race"))
+		racepkg = mkpkg("runtime/race")
 		racepkg.Name = "race"
 	}
 
@@ -549,14 +549,14 @@ func addidir(dir string) {
 }
 
 // is this path a local name?  begins with ./ or ../ or /
-func islocalname(name *Strlit) bool {
-	return strings.HasPrefix(name.S, "/") ||
-		Ctxt.Windows != 0 && len(name.S) >= 3 && yy_isalpha(int(name.S[0])) && name.S[1] == ':' && name.S[2] == '/' ||
-		strings.HasPrefix(name.S, "./") || name.S == "." ||
-		strings.HasPrefix(name.S, "../") || name.S == ".."
+func islocalname(name string) bool {
+	return strings.HasPrefix(name, "/") ||
+		Ctxt.Windows != 0 && len(name) >= 3 && yy_isalpha(int(name[0])) && name[1] == ':' && name[2] == '/' ||
+		strings.HasPrefix(name, "./") || name == "." ||
+		strings.HasPrefix(name, "../") || name == ".."
 }
 
-func findpkg(name *Strlit) bool {
+func findpkg(name string) bool {
 	if islocalname(name) {
 		if safemode != 0 || nolocalimports != 0 {
 			return false
@@ -565,12 +565,12 @@ func findpkg(name *Strlit) bool {
 		// try .a before .6.  important for building libraries:
 		// if there is an array.6 in the array.a library,
 		// want to find all of array.a, not just array.6.
-		namebuf = fmt.Sprintf("%v.a", Zconv(name, 0))
+		namebuf = fmt.Sprintf("%s.a", name)
 
 		if obj.Access(namebuf, 0) >= 0 {
 			return true
 		}
-		namebuf = fmt.Sprintf("%v.%c", Zconv(name, 0), Thearch.Thechar)
+		namebuf = fmt.Sprintf("%s.%c", name, Thearch.Thechar)
 		if obj.Access(namebuf, 0) >= 0 {
 			return true
 		}
@@ -582,17 +582,17 @@ func findpkg(name *Strlit) bool {
 	// as different from "encoding/base64".
 	var q string
 	_ = q
-	if path.Clean(name.S) != name.S {
-		Yyerror("non-canonical import path %v (should be %s)", Zconv(name, 0), q)
+	if path.Clean(name) != name {
+		Yyerror("non-canonical import path %q (should be %q)", name, q)
 		return false
 	}
 
 	for p := idirs; p != nil; p = p.link {
-		namebuf = fmt.Sprintf("%s/%v.a", p.dir, Zconv(name, 0))
+		namebuf = fmt.Sprintf("%s/%s.a", p.dir, name)
 		if obj.Access(namebuf, 0) >= 0 {
 			return true
 		}
-		namebuf = fmt.Sprintf("%s/%v.%c", p.dir, Zconv(name, 0), Thearch.Thechar)
+		namebuf = fmt.Sprintf("%s/%s.%c", p.dir, name, Thearch.Thechar)
 		if obj.Access(namebuf, 0) >= 0 {
 			return true
 		}
@@ -609,11 +609,11 @@ func findpkg(name *Strlit) bool {
 			suffix = "race"
 		}
 
-		namebuf = fmt.Sprintf("%s/pkg/%s_%s%s%s/%v.a", goroot, goos, goarch, suffixsep, suffix, Zconv(name, 0))
+		namebuf = fmt.Sprintf("%s/pkg/%s_%s%s%s/%s.a", goroot, goos, goarch, suffixsep, suffix, name)
 		if obj.Access(namebuf, 0) >= 0 {
 			return true
 		}
-		namebuf = fmt.Sprintf("%s/pkg/%s_%s%s%s/%v.%c", goroot, goos, goarch, suffixsep, suffix, Zconv(name, 0), Thearch.Thechar)
+		namebuf = fmt.Sprintf("%s/pkg/%s_%s%s%s/%s.%c", goroot, goos, goarch, suffixsep, suffix, name, Thearch.Thechar)
 		if obj.Access(namebuf, 0) >= 0 {
 			return true
 		}
@@ -623,7 +623,7 @@ func findpkg(name *Strlit) bool {
 }
 
 func fakeimport() {
-	importpkg = mkpkg(newstrlit("fake"))
+	importpkg = mkpkg("fake")
 	cannedimports("fake.6", "$$\n")
 }
 
@@ -634,7 +634,7 @@ func importfile(f *Val, line int) {
 		return
 	}
 
-	if len(f.U.Sval.S) == 0 {
+	if len(f.U.Sval) == 0 {
 		Yyerror("import path is empty")
 		fakeimport()
 		return
@@ -649,17 +649,17 @@ func importfile(f *Val, line int) {
 	// but we reserve the import path "main" to identify
 	// the main package, just as we reserve the import
 	// path "math" to identify the standard math package.
-	if f.U.Sval.S == "main" {
+	if f.U.Sval == "main" {
 		Yyerror("cannot import \"main\"")
 		errorexit()
 	}
 
-	if myimportpath != "" && f.U.Sval.S == myimportpath {
-		Yyerror("import \"%v\" while compiling that package (import cycle)", Zconv(f.U.Sval, 0))
+	if myimportpath != "" && f.U.Sval == myimportpath {
+		Yyerror("import %q while compiling that package (import cycle)", f.U.Sval)
 		errorexit()
 	}
 
-	if f.U.Sval.S == "unsafe" {
+	if f.U.Sval == "unsafe" {
 		if safemode != 0 {
 			Yyerror("cannot import package unsafe")
 			errorexit()
@@ -673,7 +673,7 @@ func importfile(f *Val, line int) {
 
 	path_ := f.U.Sval
 	if islocalname(path_) {
-		if path_.S[0] == '/' {
+		if path_[0] == '/' {
 			Yyerror("import path cannot be absolute path")
 			fakeimport()
 			return
@@ -685,9 +685,9 @@ func importfile(f *Val, line int) {
 		}
 		cleanbuf := prefix
 		cleanbuf += "/"
-		cleanbuf += path_.S
+		cleanbuf += path_
 		cleanbuf = path.Clean(cleanbuf)
-		path_ = newstrlit(cleanbuf)
+		path_ = cleanbuf
 
 		if isbadimport(path_) {
 			fakeimport()
@@ -696,7 +696,7 @@ func importfile(f *Val, line int) {
 	}
 
 	if !findpkg(path_) {
-		Yyerror("can't find import: \"%v\"", Zconv(f.U.Sval, 0))
+		Yyerror("can't find import: %q", f.U.Sval)
 		errorexit()
 	}
 
@@ -722,7 +722,7 @@ func importfile(f *Val, line int) {
 	var imp *obj.Biobuf
 	imp, err = obj.Bopenr(namebuf)
 	if err != nil {
-		Yyerror("can't open import: \"%v\": %v", Zconv(f.U.Sval, 0), err)
+		Yyerror("can't open import: %q: %v", f.U.Sval, err)
 		errorexit()
 	}
 
@@ -754,7 +754,7 @@ func importfile(f *Val, line int) {
 
 	// assume files move (get installed)
 	// so don't record the full path.
-	linehist(file[n-len(path_.S)-2:], -1, 1) // acts as #pragma lib
+	linehist(file[n-len(path_)-2:], -1, 1) // acts as #pragma lib
 
 	/*
 	 * position the input right
@@ -788,7 +788,7 @@ func importfile(f *Val, line int) {
 		return
 	}
 
-	Yyerror("no import in \"%v\"", Zconv(f.U.Sval, 0))
+	Yyerror("no import in %q", f.U.Sval)
 	unimportfile()
 }
 
@@ -1491,7 +1491,7 @@ caseout:
 	return LLITERAL
 
 strlit:
-	yylval.val.U.Sval = &Strlit{S: cp.String()}
+	yylval.val.U.Sval = internString(cp.Bytes())
 	yylval.val.Ctype = CTSTR
 	if Debug['x'] != 0 {
 		fmt.Printf("lex: string literal\n")
@@ -1500,6 +1500,18 @@ strlit:
 	return LLITERAL
 }
 
+var internedStrings = map[string]string{}
+
+func internString(b []byte) string {
+	s, ok := internedStrings[string(b)] // string(b) here doesn't allocate
+	if ok {
+		return s
+	}
+	s = string(b)
+	internedStrings[s] = s
+	return s
+}
+
 func more(pp *string) bool {
 	p := *pp
 	for p != "" && yy_isspace(int(p[0])) {
@@ -3080,21 +3092,21 @@ var yytfix = []struct {
 	}{"','", "comma"},
 }
 
-func pkgnotused(lineno int, path_ *Strlit, name string) {
+func pkgnotused(lineno int, path string, name string) {
 	// If the package was imported with a name other than the final
 	// import path element, show it explicitly in the error message.
 	// Note that this handles both renamed imports and imports of
 	// packages containing unconventional package declarations.
 	// Note that this uses / always, even on Windows, because Go import
 	// paths always use forward slashes.
-	elem := path_.S
+	elem := path
 	if i := strings.LastIndex(elem, "/"); i >= 0 {
 		elem = elem[i+1:]
 	}
 	if name == "" || elem == name {
-		yyerrorl(int(lineno), "imported and not used: \"%v\"", Zconv(path_, 0))
+		yyerrorl(int(lineno), "imported and not used: %q", path)
 	} else {
-		yyerrorl(int(lineno), "imported and not used: \"%v\" as %s", Zconv(path_, 0), name)
+		yyerrorl(int(lineno), "imported and not used: %q as %s", path, name)
 	}
 }
 

src/cmd/internal/gc/obj.go

@@ -199,12 +199,7 @@ func duintptr(s *Sym, off int, v uint64) int {
 var stringsym_gen int
 
 func stringsym(s string) *Sym {
-	var tmp struct {
-		lit Strlit
-		buf string
-	}
 	var pkg *Pkg
-
 	if len(s) > 100 {
 		// huge strings are made static to avoid long names
 		stringsym_gen++
@@ -215,8 +210,7 @@ func stringsym(s string) *Sym {
 		// small strings get named by their contents,
 		// so that multiple modules using the same string
 		// can share it.
-		tmp.lit.S = s
-		namebuf = fmt.Sprintf("\"%v\"", Zconv(&tmp.lit, 0))
+		namebuf = fmt.Sprintf("%q", s)
 		pkg = gostringpkg
 	}
 
@@ -313,8 +307,8 @@ func Datastring(s string, a *obj.Addr) {
 	a.Etype = Simtype[TINT]
 }
 
-func datagostring(sval *Strlit, a *obj.Addr) {
-	sym := stringsym(sval.S)
+func datagostring(sval string, a *obj.Addr) {
+	sym := stringsym(sval)
 	a.Type = obj.TYPE_MEM
 	a.Name = obj.NAME_EXTERN
 	a.Sym = Linksym(sym)
@@ -327,19 +321,13 @@ func dgostringptr(s *Sym, off int, str string) int {
 	if str == "" {
 		return duintptr(s, off, 0)
 	}
-
-	n := len(str)
-	lit := new(Strlit)
-	lit.S = str
-	lit.S = lit.S[:n]
-	return dgostrlitptr(s, off, lit)
+	return dgostrlitptr(s, off, &str)
 }
 
-func dgostrlitptr(s *Sym, off int, lit *Strlit) int {
+func dgostrlitptr(s *Sym, off int, lit *string) int {
 	if lit == nil {
 		return duintptr(s, off, 0)
 	}
-
 	off = int(Rnd(int64(off), int64(Widthptr)))
 	p := Thearch.Gins(obj.ADATA, nil, nil)
 	p.From.Type = obj.TYPE_MEM
@@ -348,7 +336,7 @@ func dgostrlitptr(s *Sym, off int, lit *Strlit) int {
 	p.From.Offset = int64(off)
 	p.From3.Type = obj.TYPE_CONST
 	p.From3.Offset = int64(Widthptr)
-	datagostring(lit, &p.To)
+	datagostring(*lit, &p.To)
 	p.To.Type = obj.TYPE_ADDR
 	p.To.Etype = Simtype[TINT]
 	off += Widthptr
@@ -425,18 +413,18 @@ func gdatacomplex(nam *Node, cval *Mpcplx) {
 	p.To.U.Dval = mpgetflt(&cval.Imag)
 }
 
-func gdatastring(nam *Node, sval *Strlit) {
+func gdatastring(nam *Node, sval string) {
 	var nod1 Node
 
 	p := Thearch.Gins(obj.ADATA, nam, nil)
-	Datastring(sval.S, &p.To)
+	Datastring(sval, &p.To)
 	p.From3.Type = obj.TYPE_CONST
 	p.From3.Offset = Types[Tptr].Width
 	p.To.Type = obj.TYPE_ADDR
 
 	//print("%P\n", p);
 
-	Nodconst(&nod1, Types[TINT], int64(len(sval.S)))
+	Nodconst(&nod1, Types[TINT], int64(len(sval)))
 
 	p = Thearch.Gins(obj.ADATA, nam, &nod1)
 	p.From3.Type = obj.TYPE_CONST

src/cmd/internal/gc/order.go

@@ -991,7 +991,7 @@ func orderexpr(np **Node, order *Order) {
 		haslit := false
 		for l := n.List; l != nil; l = l.Next {
 			hasbyte = hasbyte || l.N.Op == OARRAYBYTESTR
-			haslit = haslit || l.N.Op == OLITERAL && len(l.N.Val.U.Sval.S) != 0
+			haslit = haslit || l.N.Op == OLITERAL && len(l.N.Val.U.Sval) != 0
 		}
 
 		if haslit && hasbyte {

src/cmd/internal/gc/reflect.go

@@ -28,7 +28,7 @@ func sigcmp(a *Sig, b *Sig) int {
 	if b.pkg == nil {
 		return +1
 	}
-	return stringsCompare(a.pkg.Path.S, b.pkg.Path.S)
+	return stringsCompare(a.pkg.Path, b.pkg.Path)
 }
 
 func lsort(l *Sig, f func(*Sig, *Sig) int) *Sig {
@@ -473,7 +473,7 @@ func dimportpath(p *Pkg) {
 	}
 
 	if dimportpath_gopkg == nil {
-		dimportpath_gopkg = mkpkg(newstrlit("go"))
+		dimportpath_gopkg = mkpkg("go")
 		dimportpath_gopkg.Name = "go"
 	}
 
@@ -502,7 +502,7 @@ func dgopkgpath(s *Sym, ot int, pkg *Pkg) int {
 		var ns *Sym
 
 		if ns == nil {
-			ns = Pkglookup("importpath.\"\".", mkpkg(newstrlit("go")))
+			ns = Pkglookup("importpath.\"\".", mkpkg("go"))
 		}
 		return dsymptr(s, ot, ns, 0)
 	}
@@ -1280,7 +1280,7 @@ func dumptypestructs() {
 		if flag_race != 0 {
 			dimportpath(racepkg)
 		}
-		dimportpath(mkpkg(newstrlit("main")))
+		dimportpath(mkpkg("main"))
 	}
 }
 

src/cmd/internal/gc/sinit.go

@@ -443,7 +443,7 @@ func staticassign(l *Node, r *Node, out **NodeList) bool {
 	case OSTRARRAYBYTE:
 		if l.Class == PEXTERN && r.Left.Op == OLITERAL {
 			sval := r.Left.Val.U.Sval
-			slicebytes(l, sval.S, len(sval.S))
+			slicebytes(l, sval, len(sval))
 			return true
 		}
 
@@ -1368,7 +1368,7 @@ func iszero(n *Node) bool {
 			return true
 
 		case CTSTR:
-			return n.Val.U.Sval == nil || len(n.Val.U.Sval.S) == 0
+			return n.Val.U.Sval == ""
 
 		case CTBOOL:
 			return n.Val.U.Bval == 0

src/cmd/internal/gc/subr.go

@@ -353,7 +353,7 @@ func importdot(opkg *Pkg, pack *Node) {
 			}
 			s1 = Lookup(s.Name)
 			if s1.Def != nil {
-				pkgerror = fmt.Sprintf("during import \"%v\"", Zconv(opkg.Path, 0))
+				pkgerror = fmt.Sprintf("during import %q", opkg.Path)
 				redeclare(s1, pkgerror)
 				continue
 			}
@@ -368,7 +368,7 @@ func importdot(opkg *Pkg, pack *Node) {
 
 	if n == 0 {
 		// can't possibly be used - there were no symbols
-		yyerrorl(int(pack.Lineno), "imported and not used: \"%v\"", Zconv(opkg.Path, 0))
+		yyerrorl(int(pack.Lineno), "imported and not used: %q", opkg.Path)
 	}
 }
 
@@ -642,7 +642,7 @@ func (x methcmp) Less(i, j int) bool {
 		return k < 0
 	}
 	if !exportname(a.Sym.Name) {
-		k := stringsCompare(a.Sym.Pkg.Path.S, b.Sym.Pkg.Path.S)
+		k := stringsCompare(a.Sym.Pkg.Path, b.Sym.Pkg.Path)
 		if k != 0 {
 			return k < 0
 		}
@@ -941,8 +941,8 @@ func cplxsubtype(et int) int {
 	return 0
 }
 
-func eqnote(a, b *Strlit) bool {
-	return a == b || a != nil && b != nil && a.S == b.S
+func eqnote(a, b *string) bool {
+	return a == b || a != nil && b != nil && *a == *b
 }
 
 type TypePairList struct {
@@ -2454,11 +2454,11 @@ func genwrapper(rcvr *Type, method *Type, newnam *Sym, iface int) {
 
 		var v Val
 		v.Ctype = CTSTR
-		v.U.Sval = newstrlit(rcvr.Type.Sym.Pkg.Name) // package name
+		v.U.Sval = rcvr.Type.Sym.Pkg.Name // package name
 		l = list(l, nodlit(v))
-		v.U.Sval = newstrlit(rcvr.Type.Sym.Name) // type name
+		v.U.Sval = rcvr.Type.Sym.Name // type name
 		l = list(l, nodlit(v))
-		v.U.Sval = newstrlit(method.Sym.Name)
+		v.U.Sval = method.Sym.Name
 		l = list(l, nodlit(v)) // method name
 		call := Nod(OCALL, syslook("panicwrap", 0), nil)
 		call.List = l
@@ -3583,28 +3583,22 @@ func pathtoprefix(s string) string {
 	return s
 }
 
-func mkpkg(path_ *Strlit) *Pkg {
-	h := int(stringhash(path_.S) & uint32(len(phash)-1))
+func mkpkg(path string) *Pkg {
+	h := int(stringhash(path) & uint32(len(phash)-1))
 	for p := phash[h]; p != nil; p = p.Link {
-		if p.Path.S == path_.S {
+		if p.Path == path {
 			return p
 		}
 	}
 
 	p := new(Pkg)
-	p.Path = path_
-	p.Prefix = pathtoprefix(path_.S)
+	p.Path = path
+	p.Prefix = pathtoprefix(path)
 	p.Link = phash[h]
 	phash[h] = p
 	return p
 }
 
-func newstrlit(s string) *Strlit {
-	return &Strlit{
-		S: s,
-	}
-}
-
 func addinit(np **Node, init *NodeList) {
 	if init == nil {
 		return
@@ -3632,15 +3626,15 @@ var reservedimports = []string{
 	"type",
 }
 
-func isbadimport(path_ *Strlit) bool {
-	if len(path_.S) != len(path_.S) {
+func isbadimport(path string) bool {
+	if strings.Contains(path, "\x00") {
 		Yyerror("import path contains NUL")
 		return true
 	}
 
 	for i := 0; i < len(reservedimports); i++ {
-		if path_.S == reservedimports[i] {
-			Yyerror("import path \"%s\" is reserved and cannot be used", path_.S)
+		if path == reservedimports[i] {
+			Yyerror("import path %q is reserved and cannot be used", path)
 			return true
 		}
 	}
@@ -3649,29 +3643,29 @@ func isbadimport(path_ *Strlit) bool {
 	_ = s
 	var r uint
 	_ = r
-	for _, r := range path_.S {
+	for _, r := range path {
 		if r == utf8.RuneError {
-			Yyerror("import path contains invalid UTF-8 sequence: \"%v\"", Zconv(path_, 0))
+			Yyerror("import path contains invalid UTF-8 sequence: %q", path)
 			return true
 		}
 
 		if r < 0x20 || r == 0x7f {
-			Yyerror("import path contains control character: \"%v\"", Zconv(path_, 0))
+			Yyerror("import path contains control character: %q", path)
 			return true
 		}
 
 		if r == '\\' {
-			Yyerror("import path contains backslash; use slash: \"%v\"", Zconv(path_, 0))
+			Yyerror("import path contains backslash; use slash: %q", path)
 			return true
 		}
 
 		if unicode.IsSpace(rune(r)) {
-			Yyerror("import path contains space character: \"%v\"", Zconv(path_, 0))
+			Yyerror("import path contains space character: %q", path)
 			return true
 		}
 
 		if strings.ContainsRune("!\"#$%&'()*,:;<=>?[]^`{|}", r) {
-			Yyerror("import path contains invalid character '%c': \"%v\"", r, Zconv(path_, 0))
+			Yyerror("import path contains invalid character '%c': %q", r, path)
 			return true
 		}
 	}

src/cmd/internal/gc/typecheck.go

@@ -802,8 +802,8 @@ reswitch:
 					Yyerror("invalid %s index %v (index must be non-negative)", why, Nconv(n.Right, 0))
 				} else if Isfixedarray(t) && t.Bound > 0 && x >= t.Bound {
 					Yyerror("invalid array index %v (out of bounds for %d-element array)", Nconv(n.Right, 0), t.Bound)
-				} else if Isconst(n.Left, CTSTR) && x >= int64(len(n.Left.Val.U.Sval.S)) {
-					Yyerror("invalid string index %v (out of bounds for %d-byte string)", Nconv(n.Right, 0), len(n.Left.Val.U.Sval.S))
+				} else if Isconst(n.Left, CTSTR) && x >= int64(len(n.Left.Val.U.Sval)) {
+					Yyerror("invalid string index %v (out of bounds for %d-byte string)", Nconv(n.Right, 0), len(n.Left.Val.U.Sval))
 				} else if Mpcmpfixfix(n.Right.Val.U.Xval, Maxintval[TINT]) > 0 {
 					Yyerror("invalid %s index %v (index too large)", why, Nconv(n.Right, 0))
 				}
@@ -1169,7 +1169,7 @@ reswitch:
 		case TSTRING:
 			if Isconst(l, CTSTR) {
 				r := Nod(OXXX, nil, nil)
-				Nodconst(r, Types[TINT], int64(len(l.Val.U.Sval.S)))
+				Nodconst(r, Types[TINT], int64(len(l.Val.U.Sval)))
 				r.Orig = n
 				n = r
 			}
@@ -2135,8 +2135,8 @@ func checksliceindex(l *Node, r *Node, tp *Type) int {
 		} else if tp != nil && tp.Bound > 0 && Mpgetfix(r.Val.U.Xval) > tp.Bound {
 			Yyerror("invalid slice index %v (out of bounds for %d-element array)", Nconv(r, 0), tp.Bound)
 			return -1
-		} else if Isconst(l, CTSTR) && Mpgetfix(r.Val.U.Xval) > int64(len(l.Val.U.Sval.S)) {
-			Yyerror("invalid slice index %v (out of bounds for %d-byte string)", Nconv(r, 0), len(l.Val.U.Sval.S))
+		} else if Isconst(l, CTSTR) && Mpgetfix(r.Val.U.Xval) > int64(len(l.Val.U.Sval)) {
+			Yyerror("invalid slice index %v (out of bounds for %d-byte string)", Nconv(r, 0), len(l.Val.U.Sval))
 			return -1
 		} else if Mpcmpfixfix(r.Val.U.Xval, Maxintval[TINT]) > 0 {
 			Yyerror("invalid slice index %v (index too large)", Nconv(r, 0))
@@ -2705,8 +2705,8 @@ func keydup(n *Node, hash []*Node) {
 
 	case CTSTR:
 		b = 0
-		s := n.Val.U.Sval.S
-		for i := len(n.Val.U.Sval.S); i > 0; i-- {
+		s := n.Val.U.Sval
+		for i := len(n.Val.U.Sval); i > 0; i-- {
 			b = b*PRIME1 + uint32(s[0])
 			s = s[1:]
 		}
@@ -3444,7 +3444,7 @@ func stringtoarraylit(np **Node) {
 		Fatal("stringtoarraylit %N", n)
 	}
 
-	s := n.Left.Val.U.Sval.S
+	s := n.Left.Val.U.Sval
 	var l *NodeList
 	if n.Type.Type.Etype == TUINT8 {
 		// []byte

src/cmd/internal/gc/walk.go

@@ -1154,7 +1154,7 @@ func walkexpr(np **Node, init **NodeList) {
 				Yyerror("index out of bounds")
 			}
 		} else if Isconst(n.Left, CTSTR) {
-			n.Bounded = bounded(r, int64(len(n.Left.Val.U.Sval.S)))
+			n.Bounded = bounded(r, int64(len(n.Left.Val.U.Sval)))
 			if Debug['m'] != 0 && n.Bounded && !Isconst(n.Right, CTINT) {
 				Warn("index bounds check elided")
 			}
@@ -1167,7 +1167,7 @@ func walkexpr(np **Node, init **NodeList) {
 					// an ideal constant.
 					v := Mpgetfix(n.Right.Val.U.Xval)
 
-					Nodconst(n, n.Type, int64(n.Left.Val.U.Sval.S[v]))
+					Nodconst(n, n.Type, int64(n.Left.Val.U.Sval[v]))
 					n.Typecheck = 1
 				}
 			}
@@ -1308,7 +1308,7 @@ func walkexpr(np **Node, init **NodeList) {
 	// comparing the lengths instead will yield the same result
 	// without the function call.
 	case OCMPSTR:
-		if (Isconst(n.Left, CTSTR) && len(n.Left.Val.U.Sval.S) == 0) || (Isconst(n.Right, CTSTR) && len(n.Right.Val.U.Sval.S) == 0) {
+		if (Isconst(n.Left, CTSTR) && len(n.Left.Val.U.Sval) == 0) || (Isconst(n.Right, CTSTR) && len(n.Right.Val.U.Sval) == 0) {
 			r := Nod(int(n.Etype), Nod(OLEN, n.Left, nil), Nod(OLEN, n.Right, nil))
 			typecheck(&r, Erv)
 			walkexpr(&r, init)
@@ -2862,7 +2862,7 @@ func addstr(n *Node, init **NodeList) *Node {
 		sz := int64(0)
 		for l := n.List; l != nil; l = l.Next {
 			if n.Op == OLITERAL {
-				sz += int64(len(n.Val.U.Sval.S))
+				sz += int64(len(n.Val.U.Sval))
 			}
 		}
 
@@ -4100,7 +4100,7 @@ func usefield(n *Node) {
 	if field == nil {
 		Fatal("usefield %v %v without paramfld", Tconv(n.Left.Type, 0), Sconv(n.Right.Sym, 0))
 	}
-	if field.Note == nil || !strings.Contains(field.Note.S, "go:\"track\"") {
+	if field.Note == nil || !strings.Contains(*field.Note, "go:\"track\"") {
 		return
 	}
 

src/cmd/internal/gc/y.go

@@ -1228,13 +1228,13 @@ yydefault:
 				importpkg.Name = yyDollar[2].sym.Name
 				Pkglookup(yyDollar[2].sym.Name, nil).Npkg++
 			} else if importpkg.Name != yyDollar[2].sym.Name {
-				Yyerror("conflicting names %s and %s for package \"%v\"", importpkg.Name, yyDollar[2].sym.Name, Zconv(importpkg.Path, 0))
+				Yyerror("conflicting names %s and %s for package %q", importpkg.Name, yyDollar[2].sym.Name, importpkg.Path)
 			}
 			importpkg.Direct = 1
 			importpkg.Safe = curio.importsafe
 
 			if safemode != 0 && !curio.importsafe {
-				Yyerror("cannot import unsafe package \"%v\"", Zconv(importpkg.Path, 0))
+				Yyerror("cannot import unsafe package %q", importpkg.Path)
 			}
 		}
 	case 20:
@@ -2276,7 +2276,7 @@ yydefault:
 		{
 			var p *Pkg
 
-			if yyDollar[2].val.U.Sval.S == "" {
+			if yyDollar[2].val.U.Sval == "" {
 				p = importpkg
 			} else {
 				if isbadimport(yyDollar[2].val.U.Sval) {
@@ -2292,7 +2292,7 @@ yydefault:
 		{
 			var p *Pkg
 
-			if yyDollar[2].val.U.Sval.S == "" {
+			if yyDollar[2].val.U.Sval == "" {
 				p = importpkg
 			} else {
 				if isbadimport(yyDollar[2].val.U.Sval) {
@@ -3232,7 +3232,7 @@ yydefault:
 			importlist = list(importlist, yyDollar[2].node)
 
 			if Debug['E'] > 0 {
-				print("import [%v] func %lN \n", Zconv(importpkg.Path, 0), yyDollar[2].node)
+				print("import [%q] func %lN \n", importpkg.Path, yyDollar[2].node)
 				if Debug['m'] > 2 && yyDollar[2].node.Inl != nil {
 					print("inl body:%+H\n", yyDollar[2].node.Inl)
 				}

src/cmd/internal/ld/go.go

@@ -10,7 +10,6 @@ import (
 	"fmt"
 	"os"
 	"strings"
-	"unicode/utf8"
 )
 
 // go-specific code shared across loaders (5l, 6l, 8l).
@@ -757,49 +756,6 @@ func addexport() {
 	}
 }
 
-/* %Z from gc, for quoting import paths */
-func Zconv(s string, flag int) string {
-	// NOTE: Keep in sync with gc Zconv.
-	var n int
-	var fp string
-	for i := 0; i < len(s); i += n {
-		var r rune
-		r, n = utf8.DecodeRuneInString(s[i:])
-		switch r {
-		case utf8.RuneError:
-			if n == 1 {
-				fp += fmt.Sprintf("\\x%02x", s[i])
-				break
-			}
-			fallthrough
-
-			// fall through
-		default:
-			if r < ' ' {
-				fp += fmt.Sprintf("\\x%02x", r)
-				break
-			}
-
-			fp += string(r)
-
-		case '\t':
-			fp += "\\t"
-
-		case '\n':
-			fp += "\\n"
-
-		case '"',
-			'\\':
-			fp += `\` + string(r)
-
-		case 0xFEFF: // BOM, basically disallowed in source code
-			fp += "\\uFEFF"
-		}
-	}
-
-	return fp
-}
-
 type Pkg struct {
 	mark    uint8
 	checked uint8
@@ -835,7 +791,7 @@ func imported(pkg string, import_ string) {
 		return
 	}
 
-	pkg = fmt.Sprintf("\"%v\"", Zconv(pkg, 0)) // turn pkg path into quoted form, freed below
+	pkg = fmt.Sprintf("%q", pkg) // turn pkg path into quoted form, freed below
 	p := getpkg(pkg)
 	i := getpkg(import_)
 	i.impby = append(i.impby, p)