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[dev.regabi] cmd/compile: cleanup for concrete types - noder
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An automated rewrite will add concrete type assertions after
a test of n.Op(), when n can be safely type-asserted
(meaning, n is not reassigned a different type, n is not reassigned
and then used outside the scope of the type assertion,
and so on).

This sequence of CLs handles the code that the automated
rewrite does not: adding specific types to function arguments,
adjusting code not to call n.Left() etc when n may have multiple
representations, and so on.

This CL focuses on noder.go.

Passes buildall w/ toolstash -cmp.

Change-Id: Ie870126b51558e83c738add8e91a2804ed6d7f92
Reviewed-on: https://go-review.googlesource.com/c/go/+/277931
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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@rsc
rsc committed Dec 17, 2020
1 parent 5024396 commit be64c8b
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Showing 2 changed files with 58 additions and 34 deletions.
79 changes: 45 additions & 34 deletions src/cmd/compile/internal/gc/noder.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -527,13 +527,13 @@ func (p *noder) funcDecl(fun *syntax.FuncDecl) ir.Node {
if fun.Recv == nil {
if name.Name == "init" {
name = renameinit()
if t.List().Len() > 0 || t.Rlist().Len() > 0 {
if len(t.Params) > 0 || len(t.Results) > 0 {
base.ErrorfAt(f.Pos(), "func init must have no arguments and no return values")
}
}

if types.LocalPkg.Name == "main" && name.Name == "main" {
if t.List().Len() > 0 || t.Rlist().Len() > 0 {
if len(t.Params) > 0 || len(t.Results) > 0 {
base.ErrorfAt(f.Pos(), "func main must have no arguments and no return values")
}
}
Expand Down Expand Up @@ -983,10 +983,10 @@ func (p *noder) stmtsFall(stmts []syntax.Stmt, fallOK bool) []ir.Node {
for i, stmt := range stmts {
s := p.stmtFall(stmt, fallOK && i+1 == len(stmts))
if s == nil {
} else if s.Op() == ir.OBLOCK && s.List().Len() > 0 {
} else if s.Op() == ir.OBLOCK && s.(*ir.BlockStmt).List().Len() > 0 {
// Inline non-empty block.
// Empty blocks must be preserved for checkreturn.
nodes = append(nodes, s.List().Slice()...)
nodes = append(nodes, s.(*ir.BlockStmt).List().Slice()...)
} else {
nodes = append(nodes, s)
}
Expand Down Expand Up @@ -1020,22 +1020,23 @@ func (p *noder) stmtFall(stmt syntax.Stmt, fallOK bool) ir.Node {
return liststmt(p.decls(stmt.DeclList))
case *syntax.AssignStmt:
if stmt.Op != 0 && stmt.Op != syntax.Def {
n := p.nod(stmt, ir.OASOP, p.expr(stmt.Lhs), p.expr(stmt.Rhs))
n := ir.NewAssignOpStmt(p.pos(stmt), p.binOp(stmt.Op), p.expr(stmt.Lhs), p.expr(stmt.Rhs))
n.SetImplicit(stmt.Rhs == syntax.ImplicitOne)
n.SetSubOp(p.binOp(stmt.Op))
return n
}

rhs := p.exprList(stmt.Rhs)
if list, ok := stmt.Lhs.(*syntax.ListExpr); ok && len(list.ElemList) != 1 || len(rhs) != 1 {
n := p.nod(stmt, ir.OAS2, nil, nil)
n.PtrList().Set(p.assignList(stmt.Lhs, n, stmt.Op == syntax.Def))
n.SetColas(stmt.Op == syntax.Def)
n.PtrList().Set(p.assignList(stmt.Lhs, n, n.Colas()))
n.PtrRlist().Set(rhs)
return n
}

n := p.nod(stmt, ir.OAS, nil, nil)
n.SetLeft(p.assignList(stmt.Lhs, n, stmt.Op == syntax.Def)[0])
n.SetColas(stmt.Op == syntax.Def)
n.SetLeft(p.assignList(stmt.Lhs, n, n.Colas())[0])
n.SetRight(rhs[0])
return n

Expand Down Expand Up @@ -1110,8 +1111,6 @@ func (p *noder) assignList(expr syntax.Expr, defn ir.Node, colas bool) []ir.Node
return p.exprList(expr)
}

defn.SetColas(true)

var exprs []syntax.Expr
if list, ok := expr.(*syntax.ListExpr); ok {
exprs = list.ElemList
Expand Down Expand Up @@ -1196,27 +1195,30 @@ func (p *noder) ifStmt(stmt *syntax.IfStmt) ir.Node {

func (p *noder) forStmt(stmt *syntax.ForStmt) ir.Node {
p.openScope(stmt.Pos())
var n ir.Node
if r, ok := stmt.Init.(*syntax.RangeClause); ok {
if stmt.Cond != nil || stmt.Post != nil {
panic("unexpected RangeClause")
}

n = p.nod(r, ir.ORANGE, nil, p.expr(r.X))
n := p.nod(r, ir.ORANGE, nil, p.expr(r.X))
if r.Lhs != nil {
n.PtrList().Set(p.assignList(r.Lhs, n, r.Def))
}
} else {
n = p.nod(stmt, ir.OFOR, nil, nil)
if stmt.Init != nil {
n.PtrInit().Set1(p.stmt(stmt.Init))
}
if stmt.Cond != nil {
n.SetLeft(p.expr(stmt.Cond))
}
if stmt.Post != nil {
n.SetRight(p.stmt(stmt.Post))
n.SetColas(r.Def)
n.PtrList().Set(p.assignList(r.Lhs, n, n.Colas()))
}
n.PtrBody().Set(p.blockStmt(stmt.Body))
p.closeAnotherScope()
return n
}

n := p.nod(stmt, ir.OFOR, nil, nil)
if stmt.Init != nil {
n.PtrInit().Set1(p.stmt(stmt.Init))
}
if stmt.Cond != nil {
n.SetLeft(p.expr(stmt.Cond))
}
if stmt.Post != nil {
n.SetRight(p.stmt(stmt.Post))
}
n.PtrBody().Set(p.blockStmt(stmt.Body))
p.closeAnotherScope()
Expand All @@ -1233,17 +1235,17 @@ func (p *noder) switchStmt(stmt *syntax.SwitchStmt) ir.Node {
n.SetLeft(p.expr(stmt.Tag))
}

tswitch := n.Left()
if tswitch != nil && tswitch.Op() != ir.OTYPESW {
tswitch = nil
var tswitch *ir.TypeSwitchGuard
if l := n.Left(); l != nil && l.Op() == ir.OTYPESW {
tswitch = l.(*ir.TypeSwitchGuard)
}
n.PtrList().Set(p.caseClauses(stmt.Body, tswitch, stmt.Rbrace))

p.closeScope(stmt.Rbrace)
return n
}

func (p *noder) caseClauses(clauses []*syntax.CaseClause, tswitch ir.Node, rbrace syntax.Pos) []ir.Node {
func (p *noder) caseClauses(clauses []*syntax.CaseClause, tswitch *ir.TypeSwitchGuard, rbrace syntax.Pos) []ir.Node {
nodes := make([]ir.Node, 0, len(clauses))
for i, clause := range clauses {
p.setlineno(clause)
Expand Down Expand Up @@ -1328,10 +1330,18 @@ func (p *noder) labeledStmt(label *syntax.LabeledStmt, fallOK bool) ir.Node {
var ls ir.Node
if label.Stmt != nil { // TODO(mdempsky): Should always be present.
ls = p.stmtFall(label.Stmt, fallOK)
switch label.Stmt.(type) {
case *syntax.ForStmt, *syntax.SwitchStmt, *syntax.SelectStmt:
// Attach label directly to control statement too.
ls.SetSym(sym)
// Attach label directly to control statement too.
if ls != nil {
switch ls.Op() {
case ir.OFOR:
ls.SetSym(sym)
case ir.ORANGE:
ls.SetSym(sym)
case ir.OSWITCH:
ls.SetSym(sym)
case ir.OSELECT:
ls.SetSym(sym)
}
}
}

Expand Down Expand Up @@ -1483,8 +1493,9 @@ func (p *noder) wrapname(n syntax.Node, x ir.Node) ir.Node {
}
fallthrough
case ir.ONAME, ir.ONONAME, ir.OPACK:
x = p.nod(n, ir.OPAREN, x, nil)
x.SetImplicit(true)
p := p.nod(n, ir.OPAREN, x, nil)
p.SetImplicit(true)
return p
}
return x
}
Expand Down
13 changes: 13 additions & 0 deletions test/mainsig.go
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
// errorcheck

// Copyright 2020 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 main

func main(int) {} // ERROR "func main must have no arguments and no return values"
func main() int { return 1 } // ERROR "func main must have no arguments and no return values" "main redeclared in this block"

func init(int) {} // ERROR "func init must have no arguments and no return values"
func init() int { return 1 } // ERROR "func init must have no arguments and no return values"

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