arm: work around reg allocator bug in 5g, in two parts.

1) hack regalloc to leave R9 (m) and R10 (g) alone.
the real fix is tricker, but this gets us running
2) fix up the few places in the package sources that
the shortage of registers affects, by simplifying
some expressions.

all of this should be reverted when the right fix is in.

Fixes #1084.

R=rsc
CC=golang-dev
https://golang.org/cl/2132046

src/cmd/5g/gsubr.c

@@ -213,6 +213,9 @@ regalloc(Node *n, Type *t, Node *o)
 {
 	int i, et, fixfree, floatfree;
 
+	// guarantee R9 and R10 (m and g) are left alone. BUG.
+	reg[9] = 1;
+	reg[10] = 1;
 	if(debug['r']) {
 		fixfree = 0;
 		for(i=REGALLOC_R0; i<=REGALLOC_RMAX; i++)

src/pkg/compress/flate/huffman_bit_writer.go

@@ -110,8 +110,14 @@ func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
 }
 
 func (err WrongValueError) String() string {
-	return "huffmanBitWriter: " + err.name + " should belong to [" + strconv.Itoa64(int64(err.from)) + ";" +
-		strconv.Itoa64(int64(err.to)) + "] but actual value is " + strconv.Itoa64(int64(err.value))
+	// BUG: work around bug in 5g by simplifying expression.
+	// return "huffmanBitWriter: " + err.name + " should belong to [" + strconv.Itoa64(int64(err.from)) + ";" +
+	// 	strconv.Itoa64(int64(err.to)) + "] but actual value is " + strconv.Itoa64(int64(err.value))
+	str := "huffmanBitWriter: " + err.name + " should belong to ["
+	str += strconv.Itoa64(int64(err.from)) + ";"
+	str += strconv.Itoa64(int64(err.to)) + "] but actual value is "
+	str += strconv.Itoa64(int64(err.value))
+	return str
 }
 
 func (w *huffmanBitWriter) flushBits() {

src/pkg/gob/decode.go

@@ -867,9 +867,14 @@ func (dec *Decoder) compileDec(remoteId typeId, rt reflect.Type) (engine *decEng
 			continue
 		}
 		if !dec.compatibleType(localField.Type, wireField.id) {
-			return nil, os.ErrorString("gob: wrong type (" +
-				localField.Type.String() + ") for received field " +
-				wireStruct.name + "." + wireField.name)
+			// BUG: work around bug in 5g by simplifying expression.
+			// return nil, os.ErrorString("gob: wrong type (" +
+			//	localField.Type.String() + ") for received field " +
+			//	wireStruct.name + "." + wireField.name)
+			str := "gob: wrong type ("
+			str += localField.Type.String() + ") for received field "
+			str += wireStruct.name + "." + wireField.name
+			return nil, os.ErrorString(str)
 		}
 		op, indir, err := dec.decOpFor(wireField.id, localField.Type, localField.Name)
 		if err != nil {

src/pkg/log/log.go

@@ -86,7 +86,11 @@ func (l *Logger) formatHeader(ns int64, calldepth int) string {
 	if l.flag&(Ldate|Ltime|Lmicroseconds) != 0 {
 		t := time.SecondsToLocalTime(ns / 1e9)
 		if l.flag&(Ldate) != 0 {
-			h += itoa(int(t.Year), 4) + "/" + itoa(t.Month, 2) + "/" + itoa(t.Day, 2) + " "
+			// BUG: work around bug in 5g by simplifying expression.
+			// h += itoa(int(t.Year), 4) + "/" + itoa(t.Month, 2) + "/" + itoa(t.Day, 2) + " "
+			h += itoa(int(t.Year), 4)
+			h += "/" + itoa(t.Month, 2)
+			h += "/" + itoa(t.Day, 2) + " "
 		}
 		if l.flag&(Ltime|Lmicroseconds) != 0 {
 			h += itoa(t.Hour, 2) + ":" + itoa(t.Minute, 2) + ":" + itoa(t.Second, 2)

src/pkg/net/ip.go

@@ -200,10 +200,16 @@ func (ip IP) String() string {
 
 	// If IPv4, use dotted notation.
 	if p4 := p.To4(); len(p4) == 4 {
-		return itod(uint(p4[0])) + "." +
-			itod(uint(p4[1])) + "." +
-			itod(uint(p4[2])) + "." +
-			itod(uint(p4[3]))
+		// BUG: work around bug in 5g by simplifying expression.
+		// return itod(uint(p4[0])) + "." +
+		//	itod(uint(p4[1])) + "." +
+		//	itod(uint(p4[2])) + "." +
+		//	itod(uint(p4[3]))
+		str := itod(uint(p4[0])) + "."
+		str += itod(uint(p4[1])) + "."
+		str += itod(uint(p4[2])) + "."
+		str += itod(uint(p4[3]))
+		return str
 	}
 	if len(p) != IPv6len {
 		return "?"

src/pkg/time/format.go

@@ -356,11 +356,17 @@ type ParseError struct {
 // String is the string representation of a ParseError.
 func (e *ParseError) String() string {
 	if e.Message == "" {
-		return "parsing time " +
-			strconv.Quote(e.Value) + " as " +
-			strconv.Quote(e.Layout) + ": cannot parse " +
-			strconv.Quote(e.ValueElem) + " as " +
-			strconv.Quote(e.LayoutElem)
+		// BUG: work around bug in 5g by simplifying expression.
+		// return "parsing time " +
+		//	strconv.Quote(e.Value) + " as " +
+		//	strconv.Quote(e.Layout) + ": cannot parse " +
+		//	strconv.Quote(e.ValueElem) + " as " +
+		//	strconv.Quote(e.LayoutElem)
+		str := "parsing time " + strconv.Quote(e.Value) + " as "
+		str += strconv.Quote(e.Layout) + ": cannot parse "
+		str += strconv.Quote(e.ValueElem) + " as "
+		str += strconv.Quote(e.LayoutElem)
+		return str
 	}
 	return "parsing time " +
 		strconv.Quote(e.Value) + e.Message

src/pkg/xml/xml.go

@@ -371,8 +371,14 @@ func (p *Parser) popElement(t *EndElement) bool {
 		p.err = p.syntaxError("element <" + s.name.Local + "> closed by </" + name.Local + ">")
 		return false
 	case s.name.Space != name.Space:
-		p.err = p.syntaxError("element <" + s.name.Local + "> in space " + s.name.Space +
-			"closed by </" + name.Local + "> in space " + name.Space)
+		// BUG: work around bug in 5g by simplifying expression.
+		// p.err = p.syntaxError("element <" + s.name.Local + "> in space " + s.name.Space +
+		//	"closed by </" + name.Local + "> in space " + name.Space)
+		str := "element <" + s.name.Local
+		str += "> in space " + s.name.Space
+		str += "closed by </" + name.Local
+		str += "> in space " + name.Space
+		p.err = p.syntaxError(str)
 		return false
 	}