cmd/compile: factor out dcl stack ops into package types

Change-Id: I000bb530e00d0f0bc59e0f1366b5fb586adf4f37
Reviewed-on: https://go-review.googlesource.com/39912
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -191,7 +191,7 @@ func genhash(sym *types.Sym, t *types.Type) {
 
 	lineno = autogeneratedPos // less confusing than end of input
 	dclcontext = PEXTERN
-	markdcl()
+	types.Markdcl(lineno)
 
 	// func sym(p *T, h uintptr) uintptr
 	fn := nod(ODCLFUNC, nil, nil)
@@ -305,7 +305,7 @@ func genhash(sym *types.Sym, t *types.Type) {
 	fn = typecheck(fn, Etop)
 	typecheckslice(fn.Nbody.Slice(), Etop)
 	Curfn = nil
-	popdcl()
+	types.Popdcl()
 	if debug_dclstack != 0 {
 		testdclstack()
 	}
@@ -369,7 +369,7 @@ func geneq(sym *types.Sym, t *types.Type) {
 
 	lineno = autogeneratedPos // less confusing than end of input
 	dclcontext = PEXTERN
-	markdcl()
+	types.Markdcl(lineno)
 
 	// func sym(p, q *T) bool
 	fn := nod(ODCLFUNC, nil, nil)
@@ -497,7 +497,7 @@ func geneq(sym *types.Sym, t *types.Type) {
 	fn = typecheck(fn, Etop)
 	typecheckslice(fn.Nbody.Slice(), Etop)
 	Curfn = nil
-	popdcl()
+	types.Popdcl()
 	if debug_dclstack != 0 {
 		testdclstack()
 	}

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

@@ -1091,54 +1091,54 @@ func (p *importer) node() *Node {
 		return nodl(p.pos(), op, p.expr(), nil)
 
 	case OIF:
-		markdcl()
+		types.Markdcl(lineno)
 		n := nodl(p.pos(), OIF, nil, nil)
 		n.Ninit.Set(p.stmtList())
 		n.Left = p.expr()
 		n.Nbody.Set(p.stmtList())
 		n.Rlist.Set(p.stmtList())
-		popdcl()
+		types.Popdcl()
 		return n
 
 	case OFOR:
-		markdcl()
+		types.Markdcl(lineno)
 		n := nodl(p.pos(), OFOR, nil, nil)
 		n.Ninit.Set(p.stmtList())
 		n.Left, n.Right = p.exprsOrNil()
 		n.Nbody.Set(p.stmtList())
-		popdcl()
+		types.Popdcl()
 		return n
 
 	case ORANGE:
-		markdcl()
+		types.Markdcl(lineno)
 		n := nodl(p.pos(), ORANGE, nil, nil)
 		n.List.Set(p.stmtList())
 		n.Right = p.expr()
 		n.Nbody.Set(p.stmtList())
-		popdcl()
+		types.Popdcl()
 		return n
 
 	case OSELECT, OSWITCH:
-		markdcl()
+		types.Markdcl(lineno)
 		n := nodl(p.pos(), op, nil, nil)
 		n.Ninit.Set(p.stmtList())
 		n.Left, _ = p.exprsOrNil()
 		n.List.Set(p.stmtList())
-		popdcl()
+		types.Popdcl()
 		return n
 
 	// case OCASE, OXCASE:
 	// 	unreachable - mapped to OXCASE case below by exporter
 
 	case OXCASE:
-		markdcl()
+		types.Markdcl(lineno)
 		n := nodl(p.pos(), OXCASE, nil, nil)
-		n.Xoffset = int64(block)
+		n.Xoffset = int64(types.Block)
 		n.List.Set(p.exprList())
 		// TODO(gri) eventually we must declare variables for type switch
 		// statements (type switch statements are not yet exported)
 		n.Nbody.Set(p.stmtList())
-		popdcl()
+		types.Popdcl()
 		return n
 
 	// case OFALL:
@@ -1146,7 +1146,7 @@ func (p *importer) node() *Node {
 
 	case OXFALL:
 		n := nodl(p.pos(), OXFALL, nil, nil)
-		n.Xoffset = int64(block)
+		n.Xoffset = int64(types.Block)
 		return n
 
 	case OBREAK, OCONTINUE:
@@ -1162,7 +1162,7 @@ func (p *importer) node() *Node {
 
 	case OGOTO, OLABEL:
 		n := nodl(p.pos(), op, newname(p.expr().Sym), nil)
-		n.Sym = dclstack // context, for goto restrictions
+		n.Sym = types.Dclstack // context, for goto restrictions
 		return n
 
 	case OEND:

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

@@ -15,99 +15,12 @@ import (
 
 var externdcl []*Node
 
-var blockgen int32 // max block number
-
-var block int32 // current block number
-
-// dclstack maintains a stack of shadowed symbol declarations so that
-// popdcl can restore their declarations when a block scope ends.
-// The stack is maintained as a linked list, using Sym's Link field.
-//
-// In practice, the "stack" actually ends up forming a tree: goto and label
-// statements record the current state of dclstack so that checkgoto can
-// validate that a goto statement does not jump over any declarations or
-// into a new block scope.
-//
-// Finally, the Syms in this list are not "real" Syms as they don't actually
-// represent object names. Sym is just a convenient type for saving shadowed
-// Sym definitions, and only a subset of its fields are actually used.
-var dclstack *types.Sym
-
-func dcopy(a, b *types.Sym) {
-	a.Pkg = b.Pkg
-	a.Name = b.Name
-	a.Def = b.Def
-	a.Block = b.Block
-	a.Lastlineno = b.Lastlineno
-}
-
-func push() *types.Sym {
-	d := new(types.Sym)
-	d.Lastlineno = lineno
-	d.Link = dclstack
-	dclstack = d
-	return d
-}
-
-// pushdcl pushes the current declaration for symbol s (if any) so that
-// it can be shadowed by a new declaration within a nested block scope.
-func pushdcl(s *types.Sym) *types.Sym {
-	d := push()
-	dcopy(d, s)
-	return d
-}
-
-// popdcl pops the innermost block scope and restores all symbol declarations
-// to their previous state.
-func popdcl() {
-	d := dclstack
-	for ; d != nil && d.Name != ""; d = d.Link {
-		s := d.Pkg.Lookup(d.Name)
-		lno := s.Lastlineno
-		dcopy(s, d)
-		d.Lastlineno = lno
-	}
-
-	if d == nil {
-		Fatalf("popdcl: no mark")
-	}
-
-	dclstack = d.Link // pop mark
-	block = d.Block
-}
-
-// markdcl records the start of a new block scope for declarations.
-func markdcl() {
-	d := push()
-	d.Name = "" // used as a mark in fifo
-	d.Block = block
-
-	blockgen++
-	block = blockgen
-}
-
-// keep around for debugging
-func dumpdclstack() {
-	i := 0
-	for d := dclstack; d != nil; d = d.Link {
-		fmt.Printf("%6d  %p", i, d)
-		if d.Name != "" {
-			fmt.Printf("  '%s'  %v\n", d.Name, d.Pkg.Lookup(d.Name))
-		} else {
-			fmt.Printf("  ---\n")
-		}
-		i++
-	}
-}
-
 func testdclstack() {
-	for d := dclstack; d != nil; d = d.Link {
-		if d.Name == "" {
+	if !types.IsDclstackValid() {
 		if nerrors != 0 {
 			errorexit()
 		}
-			Fatalf("mark left on the stack")
-		}
+		Fatalf("mark left on the dclstack")
 	}
 }
 
@@ -191,7 +104,7 @@ func declare(n *Node, ctxt Class) {
 			vargen++
 			gen = vargen
 		}
-		pushdcl(s)
+		types.Pushdcl(s, lineno)
 		n.Name.Curfn = Curfn
 	}
 
@@ -199,7 +112,7 @@ func declare(n *Node, ctxt Class) {
 		n.Xoffset = 0
 	}
 
-	if s.Block == block {
+	if s.Block == types.Block {
 		// functype will print errors about duplicate function arguments.
 		// Don't repeat the error here.
 		if ctxt != PPARAM && ctxt != PPARAMOUT {
@@ -207,7 +120,7 @@ func declare(n *Node, ctxt Class) {
 		}
 	}
 
-	s.Block = block
+	s.Block = types.Block
 	s.Lastlineno = lineno
 	s.Def = asTypesNode(n)
 	n.Name.Vargen = int32(gen)
@@ -418,7 +331,7 @@ func colasdefn(left []*Node, defn *Node) {
 		}
 
 		n.Sym.SetUniq(false)
-		if n.Sym.Block == block {
+		if n.Sym.Block == types.Block {
 			continue
 		}
 
@@ -597,7 +510,7 @@ var funcdepth int32   // len(funcstack) during parsing, but then forced to be th
 // start the function.
 // called before funcargs; undone at end of funcbody.
 func funcstart(n *Node) {
-	markdcl()
+	types.Markdcl(lineno)
 	funcstack = append(funcstack, Curfn)
 	funcdepth++
 	Curfn = n
@@ -611,7 +524,7 @@ func funcbody(n *Node) {
 	if dclcontext != PAUTO {
 		Fatalf("funcbody: unexpected dclcontext %d", dclcontext)
 	}
-	popdcl()
+	types.Popdcl()
 	funcstack, Curfn = funcstack[:len(funcstack)-1], funcstack[len(funcstack)-1]
 	funcdepth--
 	if funcdepth == 0 {

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

@@ -381,7 +381,6 @@ func Main(archInit func(*Arch)) {
 
 	initUniverse()
 
-	blockgen = 1
 	dclcontext = PEXTERN
 	nerrors = 0
 
@@ -756,7 +755,7 @@ func findpkg(name string) (file string, ok bool) {
 // so that the compiler can generate calls to them,
 // but does not make them visible to user code.
 func loadsys() {
-	block = 1
+	types.Block = 1
 
 	inimport = true
 	typecheckok = true

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

@@ -85,7 +85,7 @@ type linkname struct {
 }
 
 func (p *noder) node() {
-	block = 1
+	types.Block = 1
 	imported_unsafe = false
 
 	p.lineno(p.file.PkgName)
@@ -726,10 +726,10 @@ func (p *noder) stmt(stmt syntax.Stmt) *Node {
 			n.Left = p.newname(stmt.Label)
 		}
 		if op == OGOTO {
-			n.Sym = dclstack // context, for goto restriction
+			n.Sym = types.Dclstack // context, for goto restriction
 		}
 		if op == OXFALL {
-			n.Xoffset = int64(block)
+			n.Xoffset = int64(types.Block)
 		}
 		return n
 	case *syntax.CallStmt:
@@ -777,14 +777,14 @@ func (p *noder) stmt(stmt syntax.Stmt) *Node {
 }
 
 func (p *noder) blockStmt(stmt *syntax.BlockStmt) []*Node {
-	markdcl()
+	types.Markdcl(lineno)
 	nodes := p.stmts(stmt.List)
-	popdcl()
+	types.Popdcl()
 	return nodes
 }
 
 func (p *noder) ifStmt(stmt *syntax.IfStmt) *Node {
-	markdcl()
+	types.Markdcl(lineno)
 	n := p.nod(stmt, OIF, nil, nil)
 	if stmt.Init != nil {
 		n.Ninit.Set1(p.stmt(stmt.Init))
@@ -801,12 +801,12 @@ func (p *noder) ifStmt(stmt *syntax.IfStmt) *Node {
 			n.Rlist.Set1(e)
 		}
 	}
-	popdcl()
+	types.Popdcl()
 	return n
 }
 
 func (p *noder) forStmt(stmt *syntax.ForStmt) *Node {
-	markdcl()
+	types.Markdcl(lineno)
 	var n *Node
 	if r, ok := stmt.Init.(*syntax.RangeClause); ok {
 		if stmt.Cond != nil || stmt.Post != nil {
@@ -835,12 +835,12 @@ func (p *noder) forStmt(stmt *syntax.ForStmt) *Node {
 		}
 	}
 	n.Nbody.Set(p.blockStmt(stmt.Body))
-	popdcl()
+	types.Popdcl()
 	return n
 }
 
 func (p *noder) switchStmt(stmt *syntax.SwitchStmt) *Node {
-	markdcl()
+	types.Markdcl(lineno)
 	n := p.nod(stmt, OSWITCH, nil, nil)
 	if stmt.Init != nil {
 		n.Ninit.Set1(p.stmt(stmt.Init))
@@ -856,7 +856,7 @@ func (p *noder) switchStmt(stmt *syntax.SwitchStmt) *Node {
 
 	n.List.Set(p.caseClauses(stmt.Body, tswitch))
 
-	popdcl()
+	types.Popdcl()
 	return n
 }
 
@@ -864,7 +864,7 @@ func (p *noder) caseClauses(clauses []*syntax.CaseClause, tswitch *Node) []*Node
 	var nodes []*Node
 	for _, clause := range clauses {
 		p.lineno(clause)
-		markdcl()
+		types.Markdcl(lineno)
 		n := p.nod(clause, OXCASE, nil, nil)
 		if clause.Cases != nil {
 			n.List.Set(p.exprList(clause.Cases))
@@ -876,9 +876,9 @@ func (p *noder) caseClauses(clauses []*syntax.CaseClause, tswitch *Node) []*Node
 			// keep track of the instances for reporting unused
 			nn.Name.Defn = tswitch
 		}
-		n.Xoffset = int64(block)
+		n.Xoffset = int64(types.Block)
 		n.Nbody.Set(p.stmts(clause.Body))
-		popdcl()
+		types.Popdcl()
 		nodes = append(nodes, n)
 	}
 	return nodes
@@ -894,14 +894,14 @@ func (p *noder) commClauses(clauses []*syntax.CommClause) []*Node {
 	var nodes []*Node
 	for _, clause := range clauses {
 		p.lineno(clause)
-		markdcl()
+		types.Markdcl(lineno)
 		n := p.nod(clause, OXCASE, nil, nil)
 		if clause.Comm != nil {
 			n.List.Set1(p.stmt(clause.Comm))
 		}
-		n.Xoffset = int64(block)
+		n.Xoffset = int64(types.Block)
 		n.Nbody.Set(p.stmts(clause.Body))
-		popdcl()
+		types.Popdcl()
 		nodes = append(nodes, n)
 	}
 	return nodes
@@ -909,7 +909,7 @@ func (p *noder) commClauses(clauses []*syntax.CommClause) []*Node {
 
 func (p *noder) labeledStmt(label *syntax.LabeledStmt) *Node {
 	lhs := p.nod(label, OLABEL, p.newname(label.Label), nil)
-	lhs.Sym = dclstack
+	lhs.Sym = types.Dclstack
 
 	var ls *Node
 	if label.Stmt != nil { // TODO(mdempsky): Should always be present.

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

@@ -1687,7 +1687,7 @@ func genwrapper(rcvr *types.Type, method *types.Field, newnam *types.Sym, iface
 	lineno = autogeneratedPos
 
 	dclcontext = PEXTERN
-	markdcl()
+	types.Markdcl(lineno)
 
 	this := namedfield(".this", rcvr)
 	this.Left.Name.Param.Ntype = this.Right
@@ -1784,7 +1784,7 @@ func genwrapper(rcvr *types.Type, method *types.Field, newnam *types.Sym, iface
 
 	funcbody(fn)
 	Curfn = fn
-	popdcl()
+	types.Popdcl()
 	if debug_dclstack != 0 {
 		testdclstack()
 	}

src/cmd/compile/internal/types/scope.go

+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"cmd/internal/src"
+	"fmt"
+)
+
+// Declaration stack & operations
+
+var blockgen int32 = 1 // max block number
+var Block int32        // current block number
+
+// Dclstack maintains a stack of shadowed symbol declarations so that
+// popdcl can restore their declarations when a block scope ends.
+// The stack is maintained as a linked list, using Sym's Link field.
+//
+// In practice, the "stack" actually ends up forming a tree: goto and label
+// statements record the current state of Dclstack so that checkgoto can
+// validate that a goto statement does not jump over any declarations or
+// into a new block scope.
+//
+// Finally, the Syms in this list are not "real" Syms as they don't actually
+// represent object names. Sym is just a convenient type for saving shadowed
+// Sym definitions, and only a subset of its fields are actually used.
+var Dclstack *Sym
+
+func dcopy(a, b *Sym) {
+	a.Pkg = b.Pkg
+	a.Name = b.Name
+	a.Def = b.Def
+	a.Block = b.Block
+	a.Lastlineno = b.Lastlineno
+}
+
+func push(pos src.XPos) *Sym {
+	d := new(Sym)
+	d.Lastlineno = pos
+	d.Link = Dclstack
+	Dclstack = d
+	return d
+}
+
+// Pushdcl pushes the current declaration for symbol s (if any) so that
+// it can be shadowed by a new declaration within a nested block scope.
+func Pushdcl(s *Sym, pos src.XPos) *Sym {
+	d := push(pos)
+	dcopy(d, s)
+	return d
+}
+
+// Popdcl pops the innermost block scope and restores all symbol declarations
+// to their previous state.
+func Popdcl() {
+	d := Dclstack
+	for ; d != nil && d.Name != ""; d = d.Link {
+		s := d.Pkg.Lookup(d.Name)
+		lno := s.Lastlineno
+		dcopy(s, d)
+		d.Lastlineno = lno
+	}
+
+	if d == nil {
+		Fatalf("popdcl: no mark")
+	}
+
+	Dclstack = d.Link // pop mark
+	Block = d.Block
+}
+
+// Markdcl records the start of a new block scope for declarations.
+func Markdcl(lineno src.XPos) {
+	d := push(lineno)
+	d.Name = "" // used as a mark in fifo
+	d.Block = Block
+
+	blockgen++
+	Block = blockgen
+}
+
+// keep around for debugging
+func DumpDclstack() {
+	i := 0
+	for d := Dclstack; d != nil; d = d.Link {
+		fmt.Printf("%6d  %p", i, d)
+		if d.Name != "" {
+			fmt.Printf("  '%s'  %v\n", d.Name, d.Pkg.Lookup(d.Name))
+		} else {
+			fmt.Printf("  ---\n")
+		}
+		i++
+	}
+}
+
+func IsDclstackValid() bool {
+	for d := Dclstack; d != nil; d = d.Link {
+		if d.Name == "" {
+			return false
+		}
+	}
+	return true
+}