1 files changed, 280 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/noder/stmt.go b/src/cmd/compile/internal/noder/stmt.go
new file mode 100644
index 0000000000..7d79595a04
--- /dev/null
+++ b/src/cmd/compile/internal/noder/stmt.go
@@ -0,0 +1,280 @@
+// Copyright 2021 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 noder
+
+import (
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/src"
+)
+
+func (g *irgen) stmts(stmts []syntax.Stmt) []ir.Node {
+	var nodes []ir.Node
+	for _, stmt := range stmts {
+		switch s := g.stmt(stmt).(type) {
+		case nil: // EmptyStmt
+		case *ir.BlockStmt:
+			nodes = append(nodes, s.List...)
+		default:
+			nodes = append(nodes, s)
+		}
+	}
+	return nodes
+}
+
+func (g *irgen) stmt(stmt syntax.Stmt) ir.Node {
+	// TODO(mdempsky): Remove dependency on typecheck.
+	return typecheck.Stmt(g.stmt0(stmt))
+}
+
+func (g *irgen) stmt0(stmt syntax.Stmt) ir.Node {
+	switch stmt := stmt.(type) {
+	case nil, *syntax.EmptyStmt:
+		return nil
+	case *syntax.LabeledStmt:
+		return g.labeledStmt(stmt)
+	case *syntax.BlockStmt:
+		return ir.NewBlockStmt(g.pos(stmt), g.blockStmt(stmt))
+	case *syntax.ExprStmt:
+		x := g.expr(stmt.X)
+		if call, ok := x.(*ir.CallExpr); ok {
+			call.Use = ir.CallUseStmt
+		}
+		return x
+	case *syntax.SendStmt:
+		return ir.NewSendStmt(g.pos(stmt), g.expr(stmt.Chan), g.expr(stmt.Value))
+	case *syntax.DeclStmt:
+		return ir.NewBlockStmt(g.pos(stmt), g.decls(stmt.DeclList))
+
+	case *syntax.AssignStmt:
+		if stmt.Op != 0 && stmt.Op != syntax.Def {
+			op := g.op(stmt.Op, binOps[:])
+			if stmt.Rhs == syntax.ImplicitOne {
+				return IncDec(g.pos(stmt), op, g.expr(stmt.Lhs))
+			}
+			return ir.NewAssignOpStmt(g.pos(stmt), op, g.expr(stmt.Lhs), g.expr(stmt.Rhs))
+		}
+
+		rhs := g.exprList(stmt.Rhs)
+		if list, ok := stmt.Lhs.(*syntax.ListExpr); ok && len(list.ElemList) != 1 || len(rhs) != 1 {
+			n := ir.NewAssignListStmt(g.pos(stmt), ir.OAS2, nil, nil)
+			n.Def = stmt.Op == syntax.Def
+			n.Lhs = g.assignList(stmt.Lhs, n, n.Def)
+			n.Rhs = rhs
+			return n
+		}
+
+		n := ir.NewAssignStmt(g.pos(stmt), nil, nil)
+		n.Def = stmt.Op == syntax.Def
+		n.X = g.assignList(stmt.Lhs, n, n.Def)[0]
+		n.Y = rhs[0]
+		return n
+
+	case *syntax.BranchStmt:
+		return ir.NewBranchStmt(g.pos(stmt), g.tokOp(int(stmt.Tok), branchOps[:]), g.name(stmt.Label))
+	case *syntax.CallStmt:
+		return ir.NewGoDeferStmt(g.pos(stmt), g.tokOp(int(stmt.Tok), callOps[:]), g.expr(stmt.Call))
+	case *syntax.ReturnStmt:
+		return ir.NewReturnStmt(g.pos(stmt), g.exprList(stmt.Results))
+	case *syntax.IfStmt:
+		return g.ifStmt(stmt)
+	case *syntax.ForStmt:
+		return g.forStmt(stmt)
+	case *syntax.SelectStmt:
+		return g.selectStmt(stmt)
+	case *syntax.SwitchStmt:
+		return g.switchStmt(stmt)
+
+	default:
+		g.unhandled("statement", stmt)
+		panic("unreachable")
+	}
+}
+
+// TODO(mdempsky): Investigate replacing with switch statements or dense arrays.
+
+var branchOps = [...]ir.Op{
+	syntax.Break:       ir.OBREAK,
+	syntax.Continue:    ir.OCONTINUE,
+	syntax.Fallthrough: ir.OFALL,
+	syntax.Goto:        ir.OGOTO,
+}
+
+var callOps = [...]ir.Op{
+	syntax.Defer: ir.ODEFER,
+	syntax.Go:    ir.OGO,
+}
+
+func (g *irgen) tokOp(tok int, ops []ir.Op) ir.Op {
+	// TODO(mdempsky): Validate.
+	return ops[tok]
+}
+
+func (g *irgen) op(op syntax.Operator, ops []ir.Op) ir.Op {
+	// TODO(mdempsky): Validate.
+	return ops[op]
+}
+
+func (g *irgen) assignList(expr syntax.Expr, defn ir.InitNode, colas bool) []ir.Node {
+	if !colas {
+		return g.exprList(expr)
+	}
+
+	var exprs []syntax.Expr
+	if list, ok := expr.(*syntax.ListExpr); ok {
+		exprs = list.ElemList
+	} else {
+		exprs = []syntax.Expr{expr}
+	}
+
+	res := make([]ir.Node, len(exprs))
+	for i, expr := range exprs {
+		expr := expr.(*syntax.Name)
+		if expr.Value == "_" {
+			res[i] = ir.BlankNode
+			continue
+		}
+
+		if obj, ok := g.info.Uses[expr]; ok {
+			res[i] = g.obj(obj)
+			continue
+		}
+
+		name, _ := g.def(expr)
+		name.Defn = defn
+		defn.PtrInit().Append(ir.NewDecl(name.Pos(), ir.ODCL, name))
+		res[i] = name
+	}
+	return res
+}
+
+func (g *irgen) blockStmt(stmt *syntax.BlockStmt) []ir.Node {
+	return g.stmts(stmt.List)
+}
+
+func (g *irgen) ifStmt(stmt *syntax.IfStmt) ir.Node {
+	init := g.stmt(stmt.Init)
+	n := ir.NewIfStmt(g.pos(stmt), g.expr(stmt.Cond), g.blockStmt(stmt.Then), nil)
+	if stmt.Else != nil {
+		e := g.stmt(stmt.Else)
+		if e.Op() == ir.OBLOCK {
+			e := e.(*ir.BlockStmt)
+			n.Else = e.List
+		} else {
+			n.Else = []ir.Node{e}
+		}
+	}
+	return g.init(init, n)
+}
+
+func (g *irgen) forStmt(stmt *syntax.ForStmt) ir.Node {
+	if r, ok := stmt.Init.(*syntax.RangeClause); ok {
+		n := ir.NewRangeStmt(g.pos(r), nil, nil, g.expr(r.X), nil)
+		if r.Lhs != nil {
+			n.Def = r.Def
+			lhs := g.assignList(r.Lhs, n, n.Def)
+			n.Key = lhs[0]
+			if len(lhs) > 1 {
+				n.Value = lhs[1]
+			}
+		}
+		n.Body = g.blockStmt(stmt.Body)
+		return n
+	}
+
+	return ir.NewForStmt(g.pos(stmt), g.stmt(stmt.Init), g.expr(stmt.Cond), g.stmt(stmt.Post), g.blockStmt(stmt.Body))
+}
+
+func (g *irgen) selectStmt(stmt *syntax.SelectStmt) ir.Node {
+	body := make([]*ir.CommClause, len(stmt.Body))
+	for i, clause := range stmt.Body {
+		body[i] = ir.NewCommStmt(g.pos(clause), g.stmt(clause.Comm), g.stmts(clause.Body))
+	}
+	return ir.NewSelectStmt(g.pos(stmt), body)
+}
+
+func (g *irgen) switchStmt(stmt *syntax.SwitchStmt) ir.Node {
+	pos := g.pos(stmt)
+	init := g.stmt(stmt.Init)
+
+	var expr ir.Node
+	switch tag := stmt.Tag.(type) {
+	case *syntax.TypeSwitchGuard:
+		var ident *ir.Ident
+		if tag.Lhs != nil {
+			ident = ir.NewIdent(g.pos(tag.Lhs), g.name(tag.Lhs))
+		}
+		expr = ir.NewTypeSwitchGuard(pos, ident, g.expr(tag.X))
+	default:
+		expr = g.expr(tag)
+	}
+
+	body := make([]*ir.CaseClause, len(stmt.Body))
+	for i, clause := range stmt.Body {
+		// Check for an implicit clause variable before
+		// visiting body, because it may contain function
+		// literals that reference it, and then it'll be
+		// associated to the wrong function.
+		//
+		// Also, override its position to the clause's colon, so that
+		// dwarfgen can find the right scope for it later.
+		// TODO(mdempsky): We should probably just store the scope
+		// directly in the ir.Name.
+		var cv *ir.Name
+		if obj, ok := g.info.Implicits[clause]; ok {
+			cv = g.obj(obj)
+			cv.SetPos(g.makeXPos(clause.Colon))
+		}
+		body[i] = ir.NewCaseStmt(g.pos(clause), g.exprList(clause.Cases), g.stmts(clause.Body))
+		body[i].Var = cv
+	}
+
+	return g.init(init, ir.NewSwitchStmt(pos, expr, body))
+}
+
+func (g *irgen) labeledStmt(label *syntax.LabeledStmt) ir.Node {
+	sym := g.name(label.Label)
+	lhs := ir.NewLabelStmt(g.pos(label), sym)
+	ls := g.stmt(label.Stmt)
+
+	// Attach label directly to control statement too.
+	switch ls := ls.(type) {
+	case *ir.ForStmt:
+		ls.Label = sym
+	case *ir.RangeStmt:
+		ls.Label = sym
+	case *ir.SelectStmt:
+		ls.Label = sym
+	case *ir.SwitchStmt:
+		ls.Label = sym
+	}
+
+	l := []ir.Node{lhs}
+	if ls != nil {
+		if ls.Op() == ir.OBLOCK {
+			ls := ls.(*ir.BlockStmt)
+			l = append(l, ls.List...)
+		} else {
+			l = append(l, ls)
+		}
+	}
+	return ir.NewBlockStmt(src.NoXPos, l)
+}
+
+func (g *irgen) init(init ir.Node, stmt ir.InitNode) ir.InitNode {
+	if init != nil {
+		stmt.SetInit([]ir.Node{init})
+	}
+	return stmt
+}
+
+func (g *irgen) name(name *syntax.Name) *types.Sym {
+	if name == nil {
+		return nil
+	}
+	return typecheck.Lookup(name.Value)
+}