[dev.ssa] cmd/compile/internal/ssa: implement ORETJMP

Change-Id: I352c7b9aab053959bc74c15861339e1dbe545ddc
Reviewed-on: https://go-review.googlesource.com/14404
Reviewed-by: David Chase <drchase@google.com>

src/cmd/compile/internal/gc/ssa.go

@@ -583,6 +583,14 @@ func (s *state) stmt(n *Node) {
 		b.Kind = ssa.BlockRet
 		b.Control = m
 		b.AddEdgeTo(s.exit)
+	case ORETJMP:
+		s.stmtList(n.List)
+		m := s.mem()
+		b := s.endBlock()
+		b.Kind = ssa.BlockRetJmp
+		b.Aux = n.Left.Sym
+		b.Control = m
+		b.AddEdgeTo(s.exit)
 
 	case OCONTINUE, OBREAK:
 		var op string
@@ -2054,6 +2062,11 @@ func canSSA(n *Node) bool {
 	case PEXTERN, PPARAMOUT, PPARAMREF:
 		return false
 	}
+	if n.Class == PPARAM && n.String() == ".this" {
+		// wrappers generated by genwrapper need to update
+		// the .this pointer in place.
+		return false
+	}
 	return canSSAType(n.Type)
 	// TODO: try to make more variables SSAable?
 }
@@ -3475,6 +3488,11 @@ func (s *genState) genBlock(b, next *ssa.Block) {
 			s.deferReturn()
 		}
 		Prog(obj.ARET)
+	case ssa.BlockRetJmp:
+		p := Prog(obj.AJMP)
+		p.To.Type = obj.TYPE_MEM
+		p.To.Name = obj.NAME_EXTERN
+		p.To.Sym = Linksym(b.Aux.(*Sym))
 	case ssa.BlockCall:
 		if b.Succs[0] != next {
 			p := Prog(obj.AJMP)

src/cmd/compile/internal/ssa/block.go

@@ -30,6 +30,9 @@ type Block struct {
 	// has a memory control value.
 	Control *Value
 
+	// Auxiliary info for the block.  Its value depends on the Kind.
+	Aux interface{}
+
 	// The unordered set of Values that define the operation of this block.
 	// The list must include the control value, if any. (TODO: need this last condition?)
 	// After the scheduling pass, this list is ordered.
@@ -65,6 +68,9 @@ func (b *Block) String() string {
 // long form print
 func (b *Block) LongString() string {
 	s := b.Kind.String()
+	if b.Aux != nil {
+		s += fmt.Sprintf(" %s", b.Aux)
+	}
 	if b.Control != nil {
 		s += fmt.Sprintf(" %s", b.Control)
 	}

src/cmd/compile/internal/ssa/check.go

@@ -72,6 +72,22 @@ func checkFunc(f *Func) {
 			if b.Succs[0].Kind != BlockExit {
 				f.Fatalf("ret block %s has successor %s, not Exit", b, b.Succs[0].Kind)
 			}
+		case BlockRetJmp:
+			if len(b.Succs) != 1 {
+				f.Fatalf("retjmp block %s len(Succs)==%d, want 1", b, len(b.Succs))
+			}
+			if b.Control == nil {
+				f.Fatalf("retjmp block %s has nil control %s", b)
+			}
+			if !b.Control.Type.IsMemory() {
+				f.Fatalf("retjmp block %s has non-memory control value %s", b, b.Control.LongString())
+			}
+			if b.Succs[0].Kind != BlockExit {
+				f.Fatalf("retjmp block %s has successor %s, not Exit", b, b.Succs[0].Kind)
+			}
+			if b.Aux == nil {
+				f.Fatalf("retjmp block %s has nil Aux field", b)
+			}
 		case BlockDead:
 			if len(b.Succs) != 0 {
 				f.Fatalf("dead block %s has successors", b)

src/cmd/compile/internal/ssa/gen/genericOps.go

@@ -383,6 +383,7 @@ var genericBlocks = []blockData{
 	{name: "Call"},   // 2 successors, normal return and panic
 	{name: "First"},  // 2 successors, always takes the first one (second is dead)
 	{name: "Ret"},    // 1 successor, branches to exit
+	{name: "RetJmp"}, // 1 successor, branches to exit.  Jumps to b.Aux.(*gc.Sym)
 }
 
 func init() {

src/cmd/compile/internal/ssa/html.go

@@ -384,6 +384,9 @@ func (b *Block) HTML() string {
 func (b *Block) LongHTML() string {
 	// TODO: improve this for HTML?
 	s := fmt.Sprintf("<span class=\"%s ssa-block\">%s</span>", html.EscapeString(b.String()), html.EscapeString(b.Kind.String()))
+	if b.Aux != nil {
+		s += html.EscapeString(fmt.Sprintf(" {%v}", b.Aux))
+	}
 	if b.Control != nil {
 		s += fmt.Sprintf(" %s", b.Control.HTML())
 	}

src/cmd/compile/internal/ssa/opGen.go

@@ -29,6 +29,7 @@ const (
 	BlockCall
 	BlockFirst
 	BlockRet
+	BlockRetJmp
 )
 
 var blockString = [...]string{
@@ -56,6 +57,7 @@ var blockString = [...]string{
 	BlockCall:   "Call",
 	BlockFirst:  "First",
 	BlockRet:    "Ret",
+	BlockRetJmp: "RetJmp",
 }
 
 func (k BlockKind) String() string { return blockString[k] }