cmd/internal/gc: add String methods to *Mpint, *Mpflt, *Node, *NodeList, *Sym, *Type

The next CL will remove unnecessary conv calls.

Change-Id: I0e8dbd1756cdec1ef6095ae67629cd3fae0fb4a4
Reviewed-on: https://go-review.googlesource.com/9031Reviewed-by: Austin Clements <austin@google.com>

src/cmd/internal/gc/fmt.go

@@ -1591,6 +1591,10 @@ func nodedump(n *Node, flag int) string {
 	return buf.String()
 }
 
+func (s *Sym) String() string {
+	return Sconv(s, 0)
+}
+
 // Fmt "%S": syms
 // Flags:  "%hS" suppresses qualifying with package
 func Sconv(s *Sym, flag int) string {
@@ -1616,6 +1620,10 @@ func Sconv(s *Sym, flag int) string {
 	return str
 }
 
+func (t *Type) String() string {
+	return Tconv(t, 0)
+}
+
 // Fmt "%T": types.
 // Flags: 'l' print definition, not name
 //	  'h' omit 'func' and receiver from function types, short type names
@@ -1654,6 +1662,10 @@ func Tconv(t *Type, flag int) string {
 	return str
 }
 
+func (n *Node) String() string {
+	return Nconv(n, 0)
+}
+
 // Fmt '%N': Nodes.
 // Flags: 'l' suffix with "(type %T)" where possible
 //	  '+h' in debug mode, don't recurse, no multiline output
@@ -1685,6 +1697,10 @@ func Nconv(n *Node, flag int) string {
 	return str
 }
 
+func (l *NodeList) String() string {
+	return Hconv(l, 0)
+}
+
 // Fmt '%H': NodeList.
 // Flags: all those of %N plus ',': separate with comma's instead of semicolons.
 func Hconv(l *NodeList, flag int) string {

src/cmd/internal/gc/mparith2.go

@@ -288,6 +288,10 @@ func mpatofix(a *Mpint, as string) {
 	}
 }
 
+func (x *Mpint) String() string {
+	return Bconv(x, 0)
+}
+
 func Bconv(xval *Mpint, flag int) string {
 	if flag&obj.FmtSharp != 0 {
 		return fmt.Sprintf("%#x", &xval.Val)

src/cmd/internal/gc/mparith3.go

@@ -184,6 +184,10 @@ func mpatoflt(a *Mpflt, as string) {
 	}
 }
 
+func (f *Mpflt) String() string {
+	return Fconv(f, 0)
+}
+
 func Fconv(fvp *Mpflt, flag int) string {
 	if flag&obj.FmtSharp == 0 {
 		return fvp.Val.Format('b', 0)