[dev.regabi] cmd/compile: separate CommStmt from CaseStmt

Like go/ast and cmd/compile/internal/syntax before it, package ir now
has separate concrete representations for switch-case clauses and
select-communication clauses.

Passes toolstash -cmp.

Change-Id: I32667cbae251fe7881be0f434388478433b2414f
Reviewed-on: https://go-review.googlesource.com/c/go/+/280443
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

src/cmd/compile/internal/ir/mknode.go

@@ -38,6 +38,7 @@ func main() {
 	ntypeType := lookup("Ntype")
 	nodesType := lookup("Nodes")
 	slicePtrCaseStmtType := types.NewSlice(types.NewPointer(lookup("CaseStmt")))
+	slicePtrCommStmtType := types.NewSlice(types.NewPointer(lookup("CommStmt")))
 	ptrFieldType := types.NewPointer(lookup("Field"))
 	slicePtrFieldType := types.NewSlice(ptrFieldType)
 	ptrIdentType := types.NewPointer(lookup("Ident"))
@@ -79,6 +80,8 @@ func main() {
 					fmt.Fprintf(&buf, "c.%s = c.%s.Copy()\n", name, name)
 				case is(slicePtrCaseStmtType):
 					fmt.Fprintf(&buf, "c.%s = copyCases(c.%s)\n", name, name)
+				case is(slicePtrCommStmtType):
+					fmt.Fprintf(&buf, "c.%s = copyComms(c.%s)\n", name, name)
 				case is(ptrFieldType):
 					fmt.Fprintf(&buf, "if c.%s != nil { c.%s = c.%s.copy() }\n", name, name, name)
 				case is(slicePtrFieldType):
@@ -99,6 +102,8 @@ func main() {
 				fmt.Fprintf(&buf, "err = maybeDoList(n.%s, err, do)\n", name)
 			case is(slicePtrCaseStmtType):
 				fmt.Fprintf(&buf, "err = maybeDoCases(n.%s, err, do)\n", name)
+			case is(slicePtrCommStmtType):
+				fmt.Fprintf(&buf, "err = maybeDoComms(n.%s, err, do)\n", name)
 			case is(ptrFieldType):
 				fmt.Fprintf(&buf, "err = maybeDoField(n.%s, err, do)\n", name)
 			case is(slicePtrFieldType):
@@ -120,6 +125,8 @@ func main() {
 				fmt.Fprintf(&buf, "editList(n.%s, edit)\n", name)
 			case is(slicePtrCaseStmtType):
 				fmt.Fprintf(&buf, "editCases(n.%s, edit)\n", name)
+			case is(slicePtrCommStmtType):
+				fmt.Fprintf(&buf, "editComms(n.%s, edit)\n", name)
 			case is(ptrFieldType):
 				fmt.Fprintf(&buf, "editField(n.%s, edit)\n", name)
 			case is(slicePtrFieldType):

src/cmd/compile/internal/ir/node_gen.go

@@ -239,7 +239,6 @@ func (n *CaseStmt) doChildren(do func(Node) error) error {
 	err = maybeDoList(n.init, err, do)
 	err = maybeDo(n.Var, err, do)
 	err = maybeDoList(n.List, err, do)
-	err = maybeDo(n.Comm, err, do)
 	err = maybeDoList(n.Body, err, do)
 	return err
 }
@@ -247,7 +246,6 @@ func (n *CaseStmt) editChildren(edit func(Node) Node) {
 	editList(n.init, edit)
 	n.Var = maybeEdit(n.Var, edit)
 	editList(n.List, edit)
-	n.Comm = maybeEdit(n.Comm, edit)
 	editList(n.Body, edit)
 }
 
@@ -295,6 +293,29 @@ func (n *ClosureReadExpr) editChildren(edit func(Node) Node) {
 	editList(n.init, edit)
 }
 
+func (n *CommStmt) Format(s fmt.State, verb rune) { FmtNode(n, s, verb) }
+func (n *CommStmt) copy() Node {
+	c := *n
+	c.init = c.init.Copy()
+	c.List = c.List.Copy()
+	c.Body = c.Body.Copy()
+	return &c
+}
+func (n *CommStmt) doChildren(do func(Node) error) error {
+	var err error
+	err = maybeDoList(n.init, err, do)
+	err = maybeDoList(n.List, err, do)
+	err = maybeDo(n.Comm, err, do)
+	err = maybeDoList(n.Body, err, do)
+	return err
+}
+func (n *CommStmt) editChildren(edit func(Node) Node) {
+	editList(n.init, edit)
+	editList(n.List, edit)
+	n.Comm = maybeEdit(n.Comm, edit)
+	editList(n.Body, edit)
+}
+
 func (n *CompLitExpr) Format(s fmt.State, verb rune) { FmtNode(n, s, verb) }
 func (n *CompLitExpr) copy() Node {
 	c := *n
@@ -781,20 +802,20 @@ func (n *SelectStmt) Format(s fmt.State, verb rune) { FmtNode(n, s, verb) }
 func (n *SelectStmt) copy() Node {
 	c := *n
 	c.init = c.init.Copy()
-	c.Cases = copyCases(c.Cases)
+	c.Cases = copyComms(c.Cases)
 	c.Compiled = c.Compiled.Copy()
 	return &c
 }
 func (n *SelectStmt) doChildren(do func(Node) error) error {
 	var err error
 	err = maybeDoList(n.init, err, do)
-	err = maybeDoCases(n.Cases, err, do)
+	err = maybeDoComms(n.Cases, err, do)
 	err = maybeDoList(n.Compiled, err, do)
 	return err
 }
 func (n *SelectStmt) editChildren(edit func(Node) Node) {
 	editList(n.init, edit)
-	editCases(n.Cases, edit)
+	editComms(n.Cases, edit)
 	editList(n.Compiled, edit)
 }
 

src/cmd/compile/internal/ir/stmt.go

@@ -178,19 +178,17 @@ type CaseStmt struct {
 	miniStmt
 	Var  Node  // declared variable for this case in type switch
 	List Nodes // list of expressions for switch, early select
-	Comm Node  // communication case (Exprs[0]) after select is type-checked
 	Body Nodes
 }
 
 func NewCaseStmt(pos src.XPos, list, body []Node) *CaseStmt {
-	n := &CaseStmt{}
+	n := &CaseStmt{List: list, Body: body}
 	n.pos = pos
 	n.op = OCASE
-	n.List.Set(list)
-	n.Body.Set(body)
 	return n
 }
 
+// TODO(mdempsky): Generate these with mknode.go.
 func copyCases(list []*CaseStmt) []*CaseStmt {
 	if list == nil {
 		return nil
@@ -199,7 +197,6 @@ func copyCases(list []*CaseStmt) []*CaseStmt {
 	copy(c, list)
 	return c
 }
-
 func maybeDoCases(list []*CaseStmt, err error, do func(Node) error) error {
 	if err != nil {
 		return err
@@ -213,7 +210,6 @@ func maybeDoCases(list []*CaseStmt, err error, do func(Node) error) error {
 	}
 	return nil
 }
-
 func editCases(list []*CaseStmt, edit func(Node) Node) {
 	for i, x := range list {
 		if x != nil {
@@ -222,6 +218,50 @@ func editCases(list []*CaseStmt, edit func(Node) Node) {
 	}
 }
 
+type CommStmt struct {
+	miniStmt
+	List Nodes // list of expressions for switch, early select
+	Comm Node  // communication case (Exprs[0]) after select is type-checked
+	Body Nodes
+}
+
+func NewCommStmt(pos src.XPos, list, body []Node) *CommStmt {
+	n := &CommStmt{List: list, Body: body}
+	n.pos = pos
+	n.op = OCASE
+	return n
+}
+
+// TODO(mdempsky): Generate these with mknode.go.
+func copyComms(list []*CommStmt) []*CommStmt {
+	if list == nil {
+		return nil
+	}
+	c := make([]*CommStmt, len(list))
+	copy(c, list)
+	return c
+}
+func maybeDoComms(list []*CommStmt, err error, do func(Node) error) error {
+	if err != nil {
+		return err
+	}
+	for _, x := range list {
+		if x != nil {
+			if err := do(x); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+func editComms(list []*CommStmt, edit func(Node) Node) {
+	for i, x := range list {
+		if x != nil {
+			list[i] = edit(x).(*CommStmt)
+		}
+	}
+}
+
 // A ForStmt is a non-range for loop: for Init; Cond; Post { Body }
 // Op can be OFOR or OFORUNTIL (!Cond).
 type ForStmt struct {
@@ -365,18 +405,17 @@ func (n *ReturnStmt) SetOrig(x Node) { n.orig = x }
 type SelectStmt struct {
 	miniStmt
 	Label    *types.Sym
-	Cases    []*CaseStmt
+	Cases    []*CommStmt
 	HasBreak bool
 
 	// TODO(rsc): Instead of recording here, replace with a block?
 	Compiled Nodes // compiled form, after walkswitch
 }
 
-func NewSelectStmt(pos src.XPos, cases []*CaseStmt) *SelectStmt {
+func NewSelectStmt(pos src.XPos, cases []*CommStmt) *SelectStmt {
-	n := &SelectStmt{}
+	n := &SelectStmt{Cases: cases}
 	n.pos = pos
 	n.op = OSELECT
-	n.Cases = cases
 	return n
 }
 
@@ -407,10 +446,9 @@ type SwitchStmt struct {
 }
 
 func NewSwitchStmt(pos src.XPos, tag Node, cases []*CaseStmt) *SwitchStmt {
-	n := &SwitchStmt{Tag: tag}
+	n := &SwitchStmt{Tag: tag, Cases: cases}
 	n.pos = pos
 	n.op = OSWITCH
-	n.Cases = cases
 	return n
 }
 

src/cmd/compile/internal/noder/noder.go

@@ -1266,8 +1266,8 @@ func (p *noder) simpleStmt(stmt syntax.SimpleStmt) []ir.Node {
 	return []ir.Node{p.stmt(stmt)}
 }
 
-func (p *noder) commClauses(clauses []*syntax.CommClause, rbrace syntax.Pos) []*ir.CaseStmt {
+func (p *noder) commClauses(clauses []*syntax.CommClause, rbrace syntax.Pos) []*ir.CommStmt {
-	nodes := make([]*ir.CaseStmt, len(clauses))
+	nodes := make([]*ir.CommStmt, len(clauses))
 	for i, clause := range clauses {
 		p.setlineno(clause)
 		if i > 0 {
@@ -1275,7 +1275,7 @@ func (p *noder) commClauses(clauses []*syntax.CommClause, rbrace syntax.Pos) []*
 		}
 		p.openScope(clause.Pos())
 
-		nodes[i] = ir.NewCaseStmt(p.pos(clause), p.simpleStmt(clause.Comm), p.stmts(clause.Body))
+		nodes[i] = ir.NewCommStmt(p.pos(clause), p.simpleStmt(clause.Comm), p.stmts(clause.Body))
 	}
 	if len(clauses) > 0 {
 		p.closeScope(rbrace)

src/cmd/compile/internal/typecheck/iexport.go

@@ -1144,7 +1144,7 @@ func (w *exportWriter) stmt(n ir.Node) {
 		w.op(n.Op())
 		w.pos(n.Pos())
 		w.stmtList(n.Init())
-		w.caseList(n.Cases, false)
+		w.commList(n.Cases)
 
 	case ir.OSWITCH:
 		n := n.(*ir.SwitchStmt)
@@ -1193,6 +1193,15 @@ func (w *exportWriter) caseList(cases []*ir.CaseStmt, namedTypeSwitch bool) {
 	}
 }
 
+func (w *exportWriter) commList(cases []*ir.CommStmt) {
+	w.uint64(uint64(len(cases)))
+	for _, cas := range cases {
+		w.pos(cas.Pos())
+		w.stmtList(cas.List)
+		w.stmtList(cas.Body)
+	}
+}
+
 func (w *exportWriter) exprList(list ir.Nodes) {
 	for _, n := range list {
 		w.expr(n)

src/cmd/compile/internal/typecheck/iimport.go

@@ -789,6 +789,14 @@ func (r *importReader) caseList(switchExpr ir.Node) []*ir.CaseStmt {
 	return cases
 }
 
+func (r *importReader) commList() []*ir.CommStmt {
+	cases := make([]*ir.CommStmt, r.uint64())
+	for i := range cases {
+		cases[i] = ir.NewCommStmt(r.pos(), r.stmtList(), r.stmtList())
+	}
+	return cases
+}
+
 func (r *importReader) exprList() []ir.Node {
 	var list []ir.Node
 	for {
@@ -1035,7 +1043,7 @@ func (r *importReader) node() ir.Node {
 	case ir.OSELECT:
 		pos := r.pos()
 		init := r.stmtList()
-		n := ir.NewSelectStmt(pos, r.caseList(nil))
+		n := ir.NewSelectStmt(pos, r.commList())
 		n.PtrInit().Set(init)
 		return n
 

src/cmd/compile/internal/walk/select.go

@@ -29,7 +29,7 @@ func walkSelect(sel *ir.SelectStmt) {
 	base.Pos = lno
 }
 
-func walkSelectCases(cases []*ir.CaseStmt) []ir.Node {
+func walkSelectCases(cases []*ir.CommStmt) []ir.Node {
 	ncas := len(cases)
 	sellineno := base.Pos
 
@@ -73,7 +73,7 @@ func walkSelectCases(cases []*ir.CaseStmt) []ir.Node {
 
 	// convert case value arguments to addresses.
 	// this rewrite is used by both the general code and the next optimization.
-	var dflt *ir.CaseStmt
+	var dflt *ir.CommStmt
 	for _, cas := range cases {
 		ir.SetPos(cas)
 		n := cas.Comm
@@ -146,7 +146,7 @@ func walkSelectCases(cases []*ir.CaseStmt) []ir.Node {
 	if dflt != nil {
 		ncas--
 	}
-	casorder := make([]*ir.CaseStmt, ncas)
+	casorder := make([]*ir.CommStmt, ncas)
 	nsends, nrecvs := 0, 0
 
 	var init []ir.Node
@@ -242,7 +242,7 @@ func walkSelectCases(cases []*ir.CaseStmt) []ir.Node {
 	}
 
 	// dispatch cases
-	dispatch := func(cond ir.Node, cas *ir.CaseStmt) {
+	dispatch := func(cond ir.Node, cas *ir.CommStmt) {
 		cond = typecheck.Expr(cond)
 		cond = typecheck.DefaultLit(cond, nil)